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Supramolecular chemistry with triptycene-based building blocks : access to new porous materials Chong, Jonathan Hoi-Chin 2009

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  SUPRAMOLECULAR CHEMISTRY WITH TRIPTYCENE-BASED BUILDING BLOCKS: ACCESS TO NEW POROUS MATERIALS    by  JONATHAN HOI-CHIN CHONG  B.Sc. (Comb. Hons. Chemistry & Biochemistry), The University of British Columbia, 2002      A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF  DOCTOR OF PHILOSOPHY   in   THE FACULTY OF GRADUATE STUDIES  (CHEMISTRY)      THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)  June 2009     © Jonathan Hoi-Chin Chong, 2009  ii Abstract  Synthetic routes to a series of triptycenyl o-phenylenediamines and o-quinones were developed. The oxidation to form o-quinone moieties was found to occur in a stepwise manner, allowing triptycenes with varying number of o-quinone units to be synthesized. Schiff-base condensation of the triptycenyl o-phenylenediamines was used to form triptycene-containing quinoxalines, phenazines, metal salphens, and phenanthrolines. Single crystal X-ray crystallography of the quinoxalines and phenazines showed that the presence of triptycenes resulted in more porous solid-state structures by disrupting efficient packing. Coordination of the quinoxalines with copper(I) iodide resulted in porous, two-dimensional coordination frameworks having solvent-filled channels. These materials retained their crystallinity on loss of the guest solvent and exhibited high thermal stabilities. One of these frameworks adsorbed solvent vapours to regenerate its original channel- containing structure, and was used to selectively remove benzene from samples of contaminated water. The thermally stable nickel salphens were used to study the relationship between internal free volume arising from intrinsic molecular geometry and accessible porosity through gas adsorption. A general trend of increased internal free volume producing increased porosity was observed. The inclusion of triptycene in these salphens was very effective in promoting porosity, with some compounds having accessible surface areas in excess of 400 m2 g-1. This observed porosity is unique as it arises from only the molecule’s intrinsic porosity and not from assembly into an ordered, porous structure. The salphens were  iii also capable of adsorbing hydrogen, with the best compound adsorbing around 1 weight% at a loading pressure of 1 atmosphere. The phenanthrolines were used to chelate copper(I) metal centres to form a bis(phenanthroline) complex. Carrying out the reaction in the presence of a cyanide source also resulted in the formation of a one-dimensional coordination polymer where the mono(phenanthroline) copper complexes are linked together by cyanide ligands, according to the preliminary solid-state structure obtained. One of the triptycenyl o-phenylenediames was used to chelate a platinum(II) metal centre, forming a model compound representative of fragments of target hexagonal and honeycomb structures.  iv TABLE OF CONTENTS Abstract ..................................................................................................................................... ii  Table of Contents ..................................................................................................................... iv  List of Tables .......................................................................................................................... vii  List of Figures ........................................................................................................................ viii  List of Schemes ...................................................................................................................... xvi  List of Symbols and Abbreviations...................................................................................... xviii  Acknowledgements ............................................................................................................... xxii  Dedication ............................................................................................................................ xxiv  Co-Authorship Statement.......................................................................................................xxv  CHAPTER 1 INTRODUCTION .......................................................................................1  1.1 Iptycenes in Supramolecular Chemistry ..............................................................1 1.1.1 Introduction to iptycenes........................................................................1 1.1.2 Synthesis and derivatization of iptycenes ..............................................3 1.1.3 Structure and crystallography ................................................................5 1.1.4 Crystal engineering ................................................................................9 1.1.5 Host-guest chemistry ...........................................................................21 1.1.6 Molecular machinery ...........................................................................33 1.1.7 Polymers ..............................................................................................38 1.1.8 Liquid crystals ......................................................................................53 1.2 Goals and Scope of this Thesis ..........................................................................61 1.3 References ..........................................................................................................64  CHAPTER 2 TRIPTYCENYL AMINES AND QUINONES .........................................70  2.1 Introduction ........................................................................................................70 2.2 Synthesis and Characterization of Aminotriptycenes ........................................71 2.3 Synthesis and Characterization of Triptycene Quinones ...................................77 2.4 Conclusions ........................................................................................................89 2.5 Experimental ......................................................................................................90 2.5.1 General .................................................................................................90 2.5.2 Procedures ............................................................................................91 2.5.3 X-ray crystallographic analysis..........................................................112 2.6 References ........................................................................................................114   v CHAPTER 3 TRIPTYCENE-BASED PYRAZINES ....................................................116  3.1 Introduction ......................................................................................................116 3.2 Synthesis ...........................................................................................................120 3.3 Characterization ...............................................................................................125 3.3.1 NMR studies ......................................................................................125 3.3.2 Thermogravimetric analysis ...............................................................126 3.3.3 Crystallographic studies .....................................................................127 3.4 Conclusions ......................................................................................................134 3.5 Experimental ....................................................................................................135 3.5.1 General ...............................................................................................135 3.5.2 Procedures ..........................................................................................136 3.5.3 X-ray crystallographic analysis..........................................................139 3.6 References ........................................................................................................143  CHAPTER 4 TRIPTYCENYL PYRAZINE METAL-ORGANIC  FRAMEWORKS .....................................................................................146  4.1 Introduction ......................................................................................................146 4.2 Preparation and Characterization of Frameworks ............................................147 4.3 Guest Exchange Studies ...................................................................................154 4.4 Conclusions ......................................................................................................160 4.5 Experimental ....................................................................................................160 4.5.1 General ...............................................................................................160 4.5.2 Procedures ..........................................................................................161 4.5.3 X-ray crystallographic analysis..........................................................163 4.6 References ........................................................................................................166  CHAPTER 5 POROUS TRIPTYCENYL METAL SALPHENS WITH  INTRINSIC FREE VOLUME .................................................................169  5.1 Introduction ......................................................................................................169 5.2 Synthesis and Porosity Studies .........................................................................171 5.3 Conclusions ......................................................................................................186 5.4 Experimental ....................................................................................................187 5.4.1 General ...............................................................................................187 5.4.2 Procedures ..........................................................................................188 5.4.3 X-ray crystallographic analysis..........................................................194 5.5 References ........................................................................................................196   CHAPTER 6 CONCLUSIONS AND FUTURE DIRECTIONS ...................................200  6.1 Overview ..........................................................................................................200 6.2 Pyrazine-Copper Metal-Organic Frameworks .................................................202 6.3 Nickel Salphens ................................................................................................203  vi 6.4 Future Directions ..............................................................................................205 6.4.1 Molecular architectures ......................................................................205 6.4.2 Phenazine-copper frameworks ...........................................................207 6.4.3 Nickel salphens ..................................................................................208 6.4.4 Porous Prussian Blue analogues ........................................................210 6.5 Experimental ....................................................................................................218 6.5.1 General ...............................................................................................218 6.5.2 Procedures ..........................................................................................219 6.5.3 X-ray crystallographic analysis..........................................................222 6.6 References ........................................................................................................226  APPENDIX 1 CRYSTALLOGRAPHIC DATA ............................................................228  APPENDIX 2 1H AND 13C NMR EXPERIMENTS .......................................................233    vii List of Tables  Table 2.1 Product distributions of nitrated triptycenes formed under  varying reaction conditions.  Adapted from “Synthesis and  Structural Investigation of New Triptycene-Based Ligands:  En Route to Shape-Persistent Dendrimers and Macrocycles  with Large Free Volume” Chong, J. H.; MacLachlan, M. J.  J. Org. Chem. 2007, 72, 8683-8690 ...........................................................73  Table 2.2 Bond lengths for quinone 162 and o-benzoquinone ..................................82  Table 3.1 1H NMR resonances of the bridgehead protons for 131-135 ...................126  Table 5.1 Synthesis of Ni salphens 191-199 and their properties ............................173  Table 5.2 Hydrogen adsorption properties of salphens 193 and 195-199 ...............184  Table A1.1 Selected crystallographic data for compound 162 ...................................228  Table A1.2 Selected crystallographic data for compounds 131-134 ..........................229  Table A1.3 Selected crystallographic data for compounds 184-186 ..........................230  Table A1.4 Selected crystallographic data for compound 197 ...................................231  Table A1.5 Selected crystallographic data for compound 200, 206, 209 and 210 .....232  Table A2.1 90° pulse lengths, power levels and delay times used in  NMR experiments ....................................................................................233  viii List of Figures  Figure 1.1 Internal free volume of triptycene ................................................................6  Figure 1.2 Solid-state structures of (a) 1 (disordered solvent not shown)  and  (b) 3 (chlorobenzene molecules shown in green) ................................7  Figure 1.3 Solid-state structure of 4 crystallized from (a) dichloromethane  (dichloromethane molecules shown in green) and  (b) benzene  with solvent-filled channels (benzene molecules shown in green) ..............8  Figure 1.4 Solid-state extended structures of (a) 5  (b) 6  (c) 7  (d) 7•p-xylene (p-xylene molecules shown in green)  (e) 8  (f) 9  (g) 10•benzene (benzene molecules shown in green). ...............................11  Figure 1.5 Solid-state extended structures of (a) tritpycene•C60•o-xylene  (C60 molecules shown in red, o-xylene molecules shown in green)  (b) 12•C60 ...................................................................................................................................................... 12  Figure 1.6 Solid-state extended structures (guest solvent removed for clarity)  of (a) 13  (b) 14  (c) 15  (d) 16 ...................................................................15  Figure 1.7 Solid-state extended structures of (a) 17  (b) 18  (c) 19 (DMSO  molecules shown in green)  (d) 20 (toluene molecules shown  in green)  (e) 21 (methanol molecules shown in green)  (f) 22 (methanol molecules shown in green)  (g) 23 (methanol  molecules shown in green) .........................................................................18  Figure 1.8 Solid-state extended structures of (a) 24  (b) 25  (c) 26 .............................20  Figure 1.9 Solid-state extended structures of (a) 28 and  (b) 29 (solvent  omitted for clarity) .....................................................................................21  Figure 1.10 Solid-state structure of [32•+•NO][SbCl6]. Nitrogen, blue; oxygen, red ....22  Figure 1.11 Solid-state extended structure of 34 (guest solvent molecules  and counterions omitted for clarity) ...........................................................24  Figure 1.12 Solid-state structures of (a) 36  (b) 37 .......................................................25  Figure 1.13 Solid-state structure of 38  (a) asymmetric unit  and  (b) extended structure .........................................................................26  Figure 1.14 Solid-state structure of 39 ..........................................................................27   ix Figure 1.15 Solid-state structures of (a) 42 and  (b) 43 .................................................28  Figure 1.16 Solid-state structures of (a) 45•46  (b) 48  (c) 49 .......................................30  Figure 1.17 Solid-state structures of (a) 54 and  (b) 55 .................................................34  Figure 1.18 Solid-state structure of 68 ..........................................................................38  Figure 1.19 Time-dependent fluorescence intensity and fluorescence  quenching (inset) of 78 exposed to TNT vapour.  Reprinted  with permission from reference 34a. © 1998, the American  Chemical Society .......................................................................................40  Figure 1.20 Stress-strain curves for (a) 98  (b) 99  (c) 100  (d) 101. D and  WH signify drawing and work hardening regions, respectively.  Adapted with permission from reference 38b. © 2007, Wiley-VCH ........48  Figure 1.21 Alignment of 105 using a stretched PVC matrix.  Reprinted  with permission from reference 40a. © 2005, the American  Chemical Society .......................................................................................50  Figure 1.22 H2 adsorption isotherms of polymer 113.  Reprinted with permission  from reference 41. © 2007, the Royal Society of Chemistry ....................52  Figure 1.23 Marbled textures exhibited by (a) 116c and  (b) 117c on cooling.  Adapted with permission from reference 43. © 2002, the Royal  Society of Chemistry..................................................................................55  Figure 1.24 Optical switching response of 119 (dashed line is switching voltage,  solid line is detector response).  Adapted with permission from  reference 44. © 2002, the American Chemical Society .............................58  Figure 2.1 ORTEP of 162. Ellipsoids are shown at the 50% probability level.  Carbon, black; oxygen, red ........................................................................81  Figure 2.2 Cyclic voltammograms of triptycenyl quinones 139, 162 and 163  recorded in 0.1 M [(n-Bu)4N]PF6/THF solutions with a scan  rate of 0.1 V s-1...........................................................................................87  Figure 3.1 Target belt-like giant macrocycle 182 .....................................................118  Figure 3.2 Representation of compounds 131-135 as model components  of macrocycle 182 ....................................................................................121  Figure 3.3 1H NMR spectrum (300 MHz, CDCl3) of 135.  (* = CHCl3,  † = water) ............................................................................124  x  Figure 3.4 MALDI-TOF mass spectrum of 135 (dithranol matrix) ..........................125  Figure 3.5 Thermogravimetric analysis of 131-135 (heating rate of 10 °C min-1) ...127  Figure 3.6 Solid-state structure of 131. Hydrogens have been omitted for clarity.  (a) View along the a-axis showing a layered structure. (b) View  along the b-axis showing interdigitated cofacial assembly.  (c) View  of π-stacked dimers.  (d) ORTEP of single molecule. Ellipsoids are  shown at the 50% probability level. Carbon, black; nitrogen, blue .........128  Figure 3.7 Solid-state structure of 132 crystallized from acetonitrile.  Hydrogens have been omitted for clarity.  (a) View showing  orthogonal layers. Guest solvent molecules have been omitted for  clarity.  (b) View down b-axis showing π-stacking (acetonitrile  molecules shown in red).  (c) ORTEP of single molecule. Ellipsoids  are shown at the 50% probability level. Carbon, black; nitrogen, blue ...130  Figure 3.8 Solid-state structure of 132 crystallized from THF. Hydrogens  have been omitted for clarity.  (a) View showing the presence of  layers with two different orientations.  (b) ORTEP of single  molecule. Ellipsoids are shown at the 50% probability level.  Carbon, black; nitrogen, blue ...................................................................131  Figure 3.9 Solid-state structure of 133. Hydrogens have been omitted for  clarity.  (a) View along the a-axis showing layered structure.  (b) View along b-axis showing interdigitated cofacial assembly  with π-stacking interactions.  (c) ORTEP of single molecule.  Ellipsoids are shown at the 50% probability level.  Carbon, black; nitrogen, blue ...................................................................132  Figure 3.10 Solid-state structure of 134. Hydrogens have been omitted for  clarity.  (a) View along the a-axis (acetonitrile molecules shown in  red).  (b) View along the b-axis. Guest solvent molecules have been  omitted for clarity.  (c) ORTEP of single molecule. Ellipsoids are  shown at the 50% probability level. Carbon, black; nitrogen, blue .........133  Figure 3.11 Zeroth (135) and first generations of the proposed  triptycenyl dendrimer ...............................................................................134   xi Figure 4.1 Solid-state structure of 184•MeCN. Hydrogens have been  omitted for clarity.  (a) View along the a-axis. Solvent molecules  have been omitted for clarity.  (b) View along the b-axis showing  (CuI)n chains. Solvent molecules have been omitted for clarity.  (c) View along the c-axis showing a solvent-filled channel  (acetonitrile molecules shown in brown).  (d) ORTEP of  asymmetric unit, solvent molecules excluded. Ellipsoids are  shown at the 50% probability level. Carbon, black;  nitrogen, blue; copper, green; iodine, red ................................................149  Figure 4.2 Solid-state structure of 185•2MeCN. Hydrogens have been  omitted for clarity.  (a) View along the a-axis showing  solvent-filled channels (acetonitrile molecules shown in brown).  (b) View along the b-axis. Solvent molecules have been omitted  for clarity.  (c) View along the c-axis. Solvent molecules have  been omitted for clarity.  (d) ORTEP of asymmetric unit, solvent  molecules excluded. Ellipsoids are shown at the 50% probability  level. Carbon, black; nitrogen, blue; copper, green; iodine, red ..............151  Figure 4.3 Solid-state structure of 186•1.5PhCN. Hydrogens have been  omitted for clarity.  (a) View of single dimer. Ellipsoids are  shown at the 50% probability level. Carbon, black; nitrogen, blue;  copper, green; iodine, red.  (b) View along the a-axis showing  herringbone layered structure. Guest solvent molecules have  been omitted for clarity. (c) View along the b-axis showing  solvent-filled voids.  Adapted from “Synthesis and Structural  Investigation of New Triptycene-Based Ligands: En Route to  Shape-Persistent Dendrimers and Macrocycles with Large Free  Volume” Chong, J. H.; MacLachlan, M. J. J. Org. Chem. 2007,  72, 8683-8690 ..........................................................................................153  Figure 4.4 Thermogravimetric analysis of 131-135 (heating rate of 10 °C min-1) ...155  Figure 4.5 Powder X-ray diffractograms of 184 evacuated and with  various guests:  (a) Predicted spectrum with acetonitrile  calculated from single crystal data;  (b) Empty framework;  (c) Adsorption of acetonitrile;  (d) Adsorption of n-pentane  (e) Adsorption of benzene ........................................................................157  Figure 4.6 Powder X-ray diffractogram of 185 following heating at 100°C  to remove coordinated acetonitrile:  (a) Predicted spectrum  calculated from single crystal data without guest acetonitrile  present.  (b) Empty framework ................................................................158   xii Figure 4.7 1H NMR measurement of benzene adsorption by 184 after 20,  40, 60, or 80 mg of 184 was added to 1.5 mL of D2O containing  0.01 M benzene. Sucrose was used as an internal standard .....................159  Figure 5.1 Thermogravimetric analysis of 191-199 (heating rate of 10 °C min-1) ...174  Figure 5.2 Molecular models used to calculate IMFV of  (a) 191  (b) 192  (c) 193  (d) 194  (e) 195  (f) 196  (g) 197  (h) 198  (i) 199.  Carbon, grey; hydrogen, white; nitrogen, blue; oxygen, red;  nickel, green .............................................................................................176  Figure 5.3 Nitrogen adsorption/desorption isotherms for  (a) 193  (b) 195  (c) 196  (d) 197  (e) 198  (f) 199  at 77 K. Filled circles  represent adsorption, open triangles represent desorption .......................178  Figure 5.4 International Union of Pure and Applied Chemistry  classification of  (a) physisorption isotherms and  (b) hysteresis  loops.  Adapted with permission from reference 17. © 1985, the  International Union of Pure and Applied Chemistry ...............................180  Figure 5.5 Powder X-ray diffractograms of  (a) 191  (b) 192  (c) 193  (d) 194  (e) 195  (f) 196  (g) 197  (h) 198  (i) 199 ...................................181  Figure 5.6 Solid-state structure of 197. Hydrogens have been omitted  for clarity.  (a) ORTEP of single molecule. Ellipsoids are shown  at the 50% probability level. Carbon, black; nitrogen, blue;  oxygen, red; nickel, green.  (b) Extended structure  (DMSO molecules shown in brown) .......................................................182  Figure 5.7 Hydrogen adsorption/desorption isotherms for (a) 193  (b) 195  (c) 196  (d) 197  (e) 198  (f) 199  at 77 K. Filled circles  represent adsorption, open triangles represent desorption .......................185  Figure 6.1 Solid-state structure of 200. Hydrogens have been omitted  for clarity.  (a) ORTEP of single molecule. Ellipsoids are  shown at 50% probability. Carbon, black; nitrogen, blue;  platinum, brown.  (b) View along a-axis (DMSO molecules  shown in green).  (c) View along b-axis (DMSO molecules  shown in green) ........................................................................................207   xiii Figure 6.2 Solid-state structure of 206. Hydrogens have been omitted  for clarity.  (a) ORTEP of single molecule. Ellipsoids are  shown at the 50% probability level. Carbon, black; nitrogen, blue.  (b) View showing stacking of molecules.  (c)  Side view of a pair  of stacked molecules.  (d) View down c-axis showing stacks  extending along the a-axis. Guest solvent has been omitted  for clarity.  (e) View down a-axis showing solvent-filled  channels (methanol molecules shown in red) ..........................................213  Figure 6.3 Solid-state structure of 209. Hydrogens have been omitted  for clarity. Carbon, black; nitrogen, blue; copper, brown;  chlorine, green.  (a) ORTEP of single molecule. Ellipsoids  are shown at the 50% probability level.  (b) View of stacked  molecules.  (c) View down the b-axis showing channels ........................215  Figure 6.4 Preliminary solid-state structure of 210. Carbon, black;  nitrogen, blue; copper, brown; chlorine, green.  (a) Asymmetric unit.  (b) View down the a-axis .....................................217  Figure A2.1 1H NMR spectrum (400 MHz, CDCl3) of 148a .......................................234  Figure A2.2 13C NMR spectrum (75.4 MHz, CDCl3) of 148a .....................................234  Figure A2.3 1H NMR spectrum (300 MHz, CDCl3) of 148b ......................................235  Figure A2.4 13C NMR spectrum (100.6 MHz, CDCl3) of 148b ..................................235  Figure A2.5 1H NMR spectrum (300 MHz, DMSO-d6) of 149a .................................236  Figure A2.6 13C NMR spectrum (100.6 MHz, DMSO-d6) of 149a .............................236  Figure A2.7 1H NMR spectrum (400 MHz, DMSO-d6) of 149b .................................237  Figure A2.8 13C NMR spectrum (100.6 MHz, DMSO-d6) of 149b .............................237  Figure A2.9 1H NMR spectrum (400 MHz, DMSO-d6) of 137 ...................................238  Figure A2.10 13C NMR spectrum (100.6 MHz, DMSO-d6) of 137 ...............................238  Figure A2.11 1H NMR spectrum (300 MHz, CDCl3) of 150b ......................................239  Figure A2.12 13C NMR spectrum (75.4 MHz, CDCl3) of 150b ....................................239  Figure A2.13 1H NMR spectrum (300 MHz, CDCl3) of 152b ......................................240  Figure A2.14 13C NMR spectrum (100.6 MHz, CDCl3) of 152b ..................................240  xiv  Figure A2.15 1H NMR spectrum (300 MHz, CDCl3) of 153b ......................................241  Figure A2.16 13C NMR spectrum (100.6 MHz, CDCl3) of 153b ..................................241  Figure A2.17 1H NMR spectrum (400 MHz, DMSO-d6) of 154b .................................242  Figure A2.18 13C NMR spectrum (100.6 MHz, DMSO-d6) of 154b .............................242  Figure A2.19 1H NMR spectrum (400 MHz, CDCl3) of 165 .........................................243  Figure A2.20 13C NMR spectrum (100.6 MHz, CDCl3) of 165.....................................243  Figure A2.21 1H NMR spectrum (300 MHz, CDCl3) of 168 .........................................244  Figure A2.22 13C NMR spectrum (100.6 MHz, CDCl3) of 168.....................................244  Figure A2.23 1H NMR spectrum (400 MHz, acetone-d6) of 174 ..................................245  Figure A2.24 13C NMR spectrum (100.6 MHz, acetone-d6) of 174 ..............................245  Figure A2.25 1H NMR spectrum (300 MHz, CDCl3) of 190 .........................................246  Figure A2.26 13C NMR spectrum (100.6 MHz, CDCl3) of 190.....................................246  Figure A2.27 1H NMR spectrum (400 MHz, DMSO-d6) of 191 ...................................247  Figure A2.28 13C NMR spectrum (100.6, DMSO-d6) of 191 ........................................247  Figure A2.29 1H NMR spectrum (300 MHz, CDCl3) of 192 .........................................248  Figure A2.30 13C NMR spectrum (75.4 MHz, CDCl3) of 192 .......................................248  Figure A2.31 1H NMR spectrum (400 MHz, DMSO-d6) of 193 ...................................249  Figure A2.32 1H NMR spectrum (400 MHz, CD2Cl2) of 194 .......................................249  Figure A2.33 13C NMR spectrum (75.4 MHz, CDCl3) of 194 .......................................250  Figure A2.34 1H NMR spectrum (400 MHz, CDCl3) of 195 .........................................250  Figure A2.35 13C NMR spectrum (100.6 MHz, CDCl3) of 195.....................................251  Figure A2.36 1H NMR spectrum (300 MHz, CDCl3) of 196 .........................................251  Figure A2.37 13C NMR spectrum (100.6 MHz, CDCl3) of 196.....................................252  xv  Figure A2.38 1H NMR spectrum (400 MHz, DMSO-d6) of 197 ...................................252  Figure A2.39 13C NMR spectrum (100.6 MHz, DMSO-d6) of 197 ...............................253  Figure A2.40 1H NMR spectrum (400 MHz, CD2Cl2) of 198 .......................................253  Figure A2.41 13C NMR spectrum (100.6 MHz, CD2Cl2) of 198 ...................................254  Figure A2.42 13C NMR spectrum from HMQC (100.6 MHz, CDCl3) of 198 ...............254  Figure A2.43 1H NMR spectrum (400 MHz, CDCl3) of 199 .........................................255  Figure A2.44 13C NMR spectrum (100.6 MHz, CDCl3) of 199.....................................255  Figure A2.45 1H NMR spectrum (300 MHz, DMSO-d6) of 200 ...................................256  Figure A2.46 1H NMR spectrum (400 MHz, CDCl3) of 206 .........................................256  Figure A2.47 13C NMR spectrum (100.6 MHz, CDCl3) of 206.....................................257  Figure A2.48 1H NMR spectrum (400 MHz, CD2Cl2) of 207 .......................................257  Figure A2.49 13C NMR spectrum (100.6 MHz, CDCl3) of 207.....................................258  Figure A2.50 1H NMR spectrum (400 MHz, CDCl3) of 208 .........................................258   xvi List of Schemes  Scheme 1.1 Single-step synthesis of triptycene using benzyne.......................................3  Scheme 1.2 Conversion between ternary and binary host-guest complexes  using acid and base ....................................................................................29  Scheme 1.3 Three-way switching for guest binding by 45 ...........................................31  Scheme 1.4 Reversible actuation of a “molecular brake” .............................................34  Scheme 1.5 Unidirectional rotation of a “molecular rotor” ...........................................35  Scheme 1.6 Formation of poly(iptycene) 103 ...............................................................49  Scheme 1.7 Formation of poly(iptycene) 105 ...............................................................49  Scheme 1.8 Formation of poly(iptycene) 109 ...............................................................51  Scheme 1.9 Formation of polymer 113 .........................................................................52  Scheme 2.1 Synthetic route to 2,3-diaminotriptycene (136) .........................................72  Scheme 2.2 Synthetic route to 2,3,6,7-tetraaminotriptycene (137) ...............................75  Scheme 2.3 Literature synthesis of 2,3,6,7,14,15-hexaaminotriptycene (138) .............76  Scheme 2.4 Synthetic route to 2,3,6,7,14,15-hexaaminotriptycene (138) .....................77  Scheme 2.5 Synthetic routes to triptycene o-quinone (139) ..........................................78  Scheme 2.6 Proposed synthetic route to triptycene bis-o-quinone (140) ......................79  Scheme 2.7 Synthetic route to dimethyltriptycene bis-o-quinone (162) .......................80  Scheme 2.8 Synthetic route to dimethyltriptycene bis-o-quinone (163) .......................80  Scheme 2.9 Proposed synthetic route to triptycene tris-o-quinone (141) ......................83  Scheme 2.10 Proposed synthetic route to dimethyltriptycene tris-o-quinone (170) .......84  Scheme 2.11 Synthetic route to mono-quinone 171 and bis-quinone 172 ......................85  Scheme 2.12 Proposed alternate synthetic route to tris-quinone 170 via 173 .................86   xvii Scheme 2.13 Proposed mechanism for reduction of triptycenyl quinones  139 and 163 ................................................................................................88  Scheme 2.14 Proposed mechanism for reduction of triptycenyl quinone 162 ................88  Scheme 3.1 Synthesis of triptycenyl quinoxalines 131 and 132 .................................120  Scheme 3.2 Synthesis of triptycenyl phenazines 133-135 ..........................................122  Scheme 4.1 Preparation of coordination frameworks 184 and 185 .............................148  Scheme 4.2 Preparation of coordination complex 186 ................................................152  Scheme 5.1 Synthesis of Ni salphens 191-199 ............................................................171  Scheme 6.1 Preparation of model complex 200 ..........................................................206  Scheme 6.2 Proposed synthetic route to salicylaldehyde 205 .....................................209  Scheme 6.3 Synthesis of triptycene-based phenanthrolines 206-208 ..........................211  Scheme 6.4 Proposed synthetic route to complex 209 ................................................218   xviii List of Symbols and Abbreviations  Abbreviation Definition ° degrees °C degrees Celsius δ chemical shift κ dielectric constant λ wavelength ν wavenumber 5PCH 4-(trans-4-pentylcyclohexyl)-benzonitrile 6CHBT 1-(trans-4-hexylcyclohexyl)-4-isothiocyanatobenzene Å Angstrom Ac acetyl AM1 Austin Model 1 [semi-empirical computational method] Anal. Calcd analysis calculated Ar aromatic atm atmosphere BET Brunauer-Emmett-Teller [theory of gas adsorption on a surface] br broad Calcd. calculated CAN cerium(IV) ammonium nitrate cat. catalytic  xix CIF crystallographic information file COF covalent organic framework CPK Corey-Pauling-Koltun [space-filling model using van der Waals radii] cps counts per second d days; doublet (NMR) DEF N,N’-diethylformamide DMAP 4-(dimethylamino)pyridine DMF N,N’-dimethylformamide DMSO dimethyl sulfoxide DSC differential scanning calorimetry E1/2 half-wave potential EDTA ethylenediaminetetraacetic acid EI electron impact [mass spectrometry method] ESI electrospray ionization [mass spectrometry method] Et ethyl EtHex 2-ethylhexyl EtOAc ethyl acetate EtOH ethanol eV electron volts h hours HMBC heteronuclear multiple bond coherence [2D NMR experiment] HMQC heteronuclear multiple quantum coherence [2D NMR experiment] HPLC high performance liquid chromatography  xx IMFV internal molecular free volume K degrees Kelvin Kassoc association constant kV kilovolts LCD liquid crystalline display m multiplet (NMR) M molar (moles per litre) m/z mass to charge ratio MALDI matrix assisted laser desorption/ionization [mass spectrometry method] MeCN acetonitrile MeOH methanol min minutes mmol millimole MOF metal-organic framework Mp. melting point MS mass spectrometry n-Bu normal-butyl NMR nuclear magnetic resonance o ortho Me methyl ORTEP Oak Ridge Thermal Ellipsoid Plot p para PAE poly(aryl ether)  xxi Ph phenyl PhCN benzonitrile PM3 Parameterized Model number 3 [semi-empirical computational method] PPD poly(phenylenebutadiynylene) PPE poly(phenyleneethynylene) ppm parts per million PPV poly(phenylenevinylene) PVC poly(vinyl chloride) Rf retention factor ROMP ring-opening olefin metathesis polymerization S Siemens s second; singlet (NMR) salphen N,N’-phenylenebis(salicylideneimine) tBu tertiary-butyl tert tertiary TFA2O trifluoroacetic anhydride Tg glass transition temperature TGA thermogravimetric analysis THF tetrahydrofuran TNT 2,4,6-trinitrotoluene TOF time of flight [mass spectrometry method] TsOH para-toluenesulfonic acid UV-vis ultraviolet-visible  xxii Acknowledgements  I would like to thank my “excellent” supervisor, Prof. Mark MacLachlan, for his outstanding mentorship and patient supervision over the years. Mark put his trust in me when he accepted me as his first 449 student and I enjoyed my experience in materials chemistry so much that I was compelled to return for my Ph.D. studies. His boundless energy and enthusiasm to do new and innovative chemistry is infectious and motivates me to try another reaction and get the beast.  I have also been very fortunate to be surrounded by a group of very bright and dedicated colleagues in the MacLachlan group. They have always been open to discuss crazy chemistry ideas, to teach me new concepts and tricks, and they don’t take offense to the periodic glovebox and dirty glassware rant e-mails. Special acknowledgements go to my mentors and collaborators over the years: Dr. Marc “Kapitan” Sauer, Dr. Amanda “Redhead” Gallant, Dr. Alfred “Gen. Sarin” Leung, Dr. Agostino “I hate computers” Pietrangelo, Joseph “Hojo” Hui, David “Superstar” Edwards, Alexandre “Master Chief” Provençal, and Xavier “X” Roy.  I am indebted to Prof. Colin Fyfe for diligently proof reading a draft version of this thesis; his feedback and insight is much appreciated.  The chemistry department staff have been outstanding in providing the chemical and technical support behind the scenes, especially those in NMR, X-ray Crystallography, Microanalytical, Glass-blowing, and Mechanical Services. In particular, I must thank Dr. Brian Patrick for teaching me the art of crystallography and for his patience in assisting me  xxiii with the inevitable and numerous problem structures. I also wish to acknowledge the generosity of the research groups in this department for “loaning” me chemicals and equipment to try out yet another test reaction.  I am indebted to the Natural Sciences and Engineering Research Council of Canada (postgraduate scholarships) and the University of British Columbia for their financial support.  Finally, I wish to thank my father, mother, and sister for their unconditional love, concern and care. Although it has been a lengthy endeavour, your confidence in me and your support have never wavered.  xxiv Dedication  To my Lord Jesus Christ, the life-giving Spirit (1 Cor. 15:45), the Firstborn from the dead (Col. 1:18; Rom. 8:29; Acts 2:32), the Author of life (Acts 3:15), in Whose name is salvation (Acts 4:12, 2:21; Rom. 10:12-13).  xxv Co-Authorship Statement  The work in this thesis was carried out under the supervision of Prof. Mark J. MacLachlan. Mass spectrometry and elemental analysis data were obtained by the Microanalytical lab at the Department of Chemistry, University of British Columbia. Unless otherwise noted, I performed the single-crystal X-ray data collection, structure solution and refinement with the assistance of Dr. Brian Patrick (Crystallographic Services, Department of Chemisty, University of British Columbia).  Chapter 1: A version of this chapter has been submitted for publication as a review article. It was written by myself with input from Prof. MacLachlan.  Chapter 2: Portions of this chapter have been published as: 1) “Robust Non- Interpenetrating Coordination Frameworks from New Shape-Persistent Building Blocks” Chong, J. H.; MacLachlan, M. J. Inorg. Chem. 2006, 45, 1442-1444.   2) “Synthesis and Structural Investigation of New Triptycene-Based Ligands: En Route to Shape-Persistent Dendrimers and Macrocycles with Large Free Volume” Chong, J. H.; MacLachlan, M. J. J. Org. Chem. 2007, 72, 8683-8690. I am the primary author of these papers with input from Prof. MacLachlan.  Chapter 3: A version of this chapter has been published as “Synthesis and Structural Investigation of New Triptycene-Based Ligands: En Route to Shape-Persistent Dendrimers and Macrocycles with Large Free Volume” Chong, J. H.; MacLachlan, M. J. J. Org. Chem. 2007, 72, 8683-8690. This article was written by myself with input from Prof. MacLachlan.   xxvi Chapter 4: Portions of this chapter are included in: 1) “Robust Non-Interpenetrating Coordination Frameworks from New Shape-Persistent Building Blocks” Chong, J. H.; MacLachlan, M. J. Inorg. Chem. 2006, 45, 1442-1444.   2) “Synthesis and Structural Investigation of New Triptycene-Based Ligands: En Route to Shape-Persistent Dendrimers and Macrocycles with Large Free Volume” Chong, J. H.; MacLachlan, M. J. J. Org. Chem. 2007, 72, 8683-8690. I am the primary author of these papers with input from Prof. MacLachlan. The powder X-ray data was collected by Anita Lam (Crystallographic Services, Department of Chemisty, University of British Columbia).  Chapter 5: A version of this chapter will be submitted for publication. It was written by myself with input from Prof. MacLachlan. IMFV calculations were performed by Joanne Chong.  Chapter 6: Xavier Roy (MacLachlan group) synthesized compounds 209-211 and obtained X-ray quality crystals for compounds 206, 209 and 210. The raw X-ray data for 206 and 209 was collected by Xavier Roy; Dr. Brian Patrick generated the reduced data sets and provided an initial solution for 209. X-ray data and the reduced data sets for 210 were obtained through the Service Crystallography at Advanced Light Source program at the Small-Crystal Crystallography Beamline 11.3.1 (Advanced Light Source, Lawrence Berkeley National Lab). Dr. Brian Patrick provided an initial solution for the structure of 210. Xavier Roy also solved the structure of 206, and assisted with refinement of the structures of 206 and 209; I performed the final series of refinements on all the structures in this chapter.   1 CHAPTER 1 INTRODUCTION †  1.1 Iptycenes in Supramolecular Chemistry  1.1.1 Introduction to iptycenes  Iptycenes are compounds with phenyl rings attached to the [2.2.2] bicyclooctatriene bridgehead system. The simplest member of this family is triptycene, named after the triptych, artwork from antiquity having three panels joined together by hinges allowing different panels to be selectively displayed. In triptycene the three phenyl ring “panels” are joined together by a single “hinge” running through carbons 9 and 10, known as the bridgehead carbons.1 Hart extended this nomenclature by proposing that iptycenes be named after the number of arene planes separated by a bridgehead system; triptycene and pentiptycene are the most common members of this family, with three and five phenyl rings, respectively.2  † A version of this chapter has been accepted for publication. Chong, J.H. and MacLachlan, M.J. (2009) Iptycenes in Supramolecular and Materials Chemistry. Chem. Soc. Rev. 2   Triptycene was first obtained by Bartlett and coworkers in 1942 through a six step synthesis beginning from anthracene and p-benzoquinone. The first step of the synthesis, a Diels-Alder cycloaddition, is used in all iptycene syntheses as the means of forming the [2.2.2] bridgehead system. Triptycene was originally synthesized to study the role of planarity and delocalization of a formal charge or radical generated at the aliphatic carbon as triptycene cannot deform to be planar like triphenylmethane.1  An unusual combination of properties allows iptycenes to be used in supramolecular applications. Firstly, they are very rigid as the high energy barrier to twisting or deformation of the bridgehead system keeps the angle between the aromatic rings at 120°. Since the aromatic rings themselves are also rigid, iptycenes are useful for adding rigidity and for creating structures with well-defined geometries. Secondly, this three-bladed geometry hinders efficient packing, producing void spaces in the clefts between the rings, termed “internal free volume”.3 It is unfavourable for these voids to remain empty and the filling of these voids can be used as a means to control supramolecular architectures. Thirdly, the presence of aromatic rings and the clefts adjacent to these rings can be used to promote supramolecular interactions with other molecules in these areas. This introductory section 3 will highlight the application of iptycenes to the supramolecular chemistry of crystal engineering, host-guest complexes, molecular machines, polymers, and liquid crystals.  1.1.2 Synthesis and derivatization of iptycenes  The conventional synthesis of iptycenes requires the Diels-Alder cycloaddition of a dienophile to an anthracenyl group to produce the [2.2.2] bridgehead geometry. The complexity of Bartlett’s synthesis was a hindrance to development of this field and there was little progress for 14 years until Wittig and Ludwig reported a single-step synthesis that greatly simplified the task of producing triptycene (Scheme 1.1).4 Instead of using benzoquinone and converting the resulting adduct to an aromatic hydrocarbon, benzyne, generated by the in situ decomposition of 2-fluorophenyl magnesium bromide, was used to introduce both the bridgehead system and the third aromatic ring. This approach opened the way to numerous triptycene derivatives, since there are a large number of potential benzyne- anthracene combinations. Pentiptycenes and even larger linear iptycenes can also be synthesized by this general strategy; tritriptycene (1)5 and supertriptycene (2)6 are two notable examples. Iptycenes containing naphthalenes2, anthracenes7 and naphthacenes7 are also accessible with this strategy, as are angular iptycenes such as heptiptycene (3)8 when different substrates are used.   Scheme 1.1.  Single-step synthesis of triptycene using benzyne. 4    Functionalized iptycenes can be used to create a wide variety of supramolecular architectures. Halides such as bromide or iodide are highly desirable, since aryl halides are widely used in transition metal-catalyzed coupling reactions and it is easy to use lithium- halogen exchange as a way to introduce a range of functional groups. Electrophilic aromatic substitution is a convenient method to functionalize the aromatic rings. Instead of a post- synthetic strategy to introduce substituents at the benzylic positions of the iptycene, it is preferable to use a precursor diene that has already been functionalized. For triptycene and pentiptycene, this means that the substituents must be introduced at the 9 and 10 positions in the anthracene precursor, which is easily done through electrophilic aromatic substitution as these positions are the most activated in anthracene.  5 The aromatic rings of iptycenes can be functionalized using different strategies. For the most part, they behave as normal and electronically independent phenyl rings apart for some through-space communication. In triptycene, the most reactive sites toward electrophilic aromatic substitution are the beta positions, not the expected alpha positions if the bridgeheads are treated as typical alkyl substituents. This allows substituents to be introduced in the beta positions of triptycene by standard electrophilic aromatic reactions. Substituents in the alpha positions are best introduced in the anthracene or dienophile precursor before triptycene formation.  1.1.3 Structure and crystallography  Iptycenes are attractive as potential scaffolds in crystal engineering for building extended porous structures because their geometry imparts rigidity and generates internal free volume. To understand the concept of internal free volume, it is instructive to consider a triangular prism enclosing triptycene (Figure 1.1). The prism can be packed in three dimensions to form a close-packed structure. However, this leaves significant void space between the aromatic rings within the prism. Another potential packing arrangement is a head-to-tail arrangement, but void spaces will still be present when this packing arrangement is extended beyond a single dimension. Regardless of the packing arrangement chosen, iptycenes will always have some void space present in the clefts between the phenyl rings, which is known as the “internal free volume”. It is unfavourable for this void space to remain unfilled and filling the voids with different guests or even parts of neighbouring triptycene molecules can produce different structures. To gain a better understanding of how to 6 rationally design porous extended structures containing triptycene, it can be helpful to see how various modifications to the building blocks affect their packing motifs in the solid state.   Figure 1.1.  Internal free volume of triptycene.  Increasing the number of bridgeheads present in an iptycene should usually increase the amount of free volume present and lead to a more porous structure. Single crystals have been obtained for three of the large iptycenes originally synthesized by Hart and coworkers. The solid-state structure of 1, crystallized from acetone, shows that the molecules pack to maximize the π interactions between the phenyl rings, filling some of the free volume (Figure 1.2a). The remaining free space is filled by disordered acetone molecules, producing solvent- filled channels.5 Siegel and coworkers were able to study the solid-state packing of the very large iptycene 3, crystallizing it from chlorobenzene. The molecules are arranged so that a phenyl ring from one molecule partially fills and widens the cleft of another molecule of 3 above it, forming layers of pairs of 3 that are separated by a layer of chlorobenzene molecules (Figure 1.2b). The slight bending of the molecule to produce a bigger cleft required for this interlocking arrangement shows that the driving force to fill the internal free volume is so great that it even occurs at the cost of distorting the rigid bridgehead system.9 Although Hart was able to obtain crystals of 2 from tetrachloroethene/ethyl acetate, there was so much disordered solvent present that the structure could not be solved.6 This is not 7 surprising since the internal free volume near the centre of 2 can only be filled by solvent molecules, which have no motion constraints as they are unlikely to interact substantially with the walls of the cavities.   Figure 1.2.  Solid-state structures of (a) 1 (disordered solvent not shown) and  (b) 3 (chlorobenzene molecules shown in green).  Another iptycene with significant internal free volume is dodecaphenyltriptycene (4), where the increased free volume is not created by adding more bridgeheads to generate more clefts, but by adding phenyl rings to the periphery to increase the size of the clefts. Single crystals of 4 were readily obtained from different solvents and the packing arrangement varied with the solvent used (Figure 1.3). Crystals grown from dichloromethane-methanol had 21% of the unit cell occupied by dichloromethane, while crystallization from benzene produced an arrangement where 51% of the cell volume was occupied by 9 benzene molecules. The central triptycene portion is not distorted since the peripheral phenyl groups are oriented in a manner that intramolecular steric repulsion does not exist, keeping the clefts accessible. The structure containing dichloromethane has some of the void space in the 8 triptycene clefts occupied by an adjacent molecule of 4, but all the void space in the structure from benzene is occupied by guest solvent. The preference of 4 to include benzene is likely favoured by the π-π interactions between the solvent and the phenyl rings of 4. Three of the guest benzene molecules are situated within the clefts while the remainder are located in large channels. Surprisingly, all the benzene molecules are well ordered because they have intermolecular π interactions that contribute to the stability of the extended structure.10  Ph PhPh Ph Ph Ph Ph Ph Ph Ph Ph Ph 4   Figure 1.3.  Solid-state structure of 4 crystallized from (a) dichloromethane (dichloromethane molecules shown in green) and  (b) benzene showing solvent-filled channels (benzene molecules shown in green).  9 1.1.4 Crystal Engineering  A variety of supramolecular interactions can be exploited to design substituted triptycenes that will self-assemble to form extended structures in the solid state. Having three separate phenyl rings allows triptycenes to be modified to have both electron-rich and electron-deficient rings within the same molecule so that they stack and self-assemble through donor-acceptor interactions. Triptycene p-quinone (5) in the solid state has these interactions between the phenyl ring and quinone, and this stacking produces a ribbon-like structure (Figure 1.4a). Increasing the donor’s electron density by adding methyl groups to the phenyl ring (6) improved the donor-acceptor interactions and decreased the interplanar distance (Figure 1.4b). Further work confirmed that other donor-acceptor combinations (7- 10) also form ribbon-like stacks (Figure 1.4c-g). The difference between the donor and acceptor is sufficiently great in 10 to produce a charge-transfer band in the solid state, making the compound wine red in solution but dark blue in the solid state. Hydrogen- bonding is also observed in 5-10 to connect adjacent ribbons to form sheets, and these sheets are further connected to form a three-dimensional extended structure. The crystals obtained from acetonitrile were free of solvent, but 7 and 10 contained guest solvent molecules when crystallized from aromatic solvents, with the guests oriented cofacially to the acceptor moieties and participating in donor-acceptor interactions. Compound 5 can also form a charge-transfer complex in the solid state when co-crystallized with small amounts of its reduced hydroquinone (11), resulting in a colour change from yellow to brown going from solution to the solid state. A solid-state structure of 50.8110.2 was similar to that of 5, with some of the molecules of 5 replaced by 11, and overlap of the hydroquinone and quinone 10 portions was observed.11     11  Fig. 1.4.  Solid-state extended structures of (a) 5  (b) 6  (c) 7  (d) 7•p-xylene (p-xylene molecules shown in green)  (e) 8  (f) 9  (g) 10•benzene (benzene molecules shown in green). 12 Triptycenes can also be assembled into two-component extended structures by using π interactions. One notable example was demonstrated in 1999 by Feringa and coworkers who found that triptycene and azatriptycene (12) co-crystallized with C60 from o-xylene to form extended networks. Triptycene formed a structure with a C60:triptycene:o-xylene ratio of 1:2:2 having each C60 encapsulated by two triptycenes, with only one cleft of the triptycene interacting with C60 (Figure 1.5a) This results in the formation of close packed sheets that are separated by a layer of triptycenes and o-xylene. The material containing 12 had a composition of 1:1 C60:12 without included solvent, where each C60 is surrounded by three azatriptycenes and all three clefts of 12 interact with C60 (Figure 1.5b). This results in a layered structure where the layers are staggered in an ab repeating arrangement. This more efficient packing observed for 12 is due to its greater affinity for C60 than for o-xylene.12     Figure 1.5.  Solid-state extended structures of (a) triptycene•C60•o-xylene (C60 molecules shown in red, o-xylene molecules shown in green)  (b) 12•C60. 13  Weak van der Waals interactions have been used to self-assemble larger triptycene- based rings and cages into porous extended structures. The solid-state structures of a series of triptycene-based expanded oxacalixarenes (13-15) showed assembly into extended tubular structures through intermolecular C-Cl···π  and π-π interactions (Figure 1.6a-c). The cis isomer 13 assembles into a structure with diamond-shaped channels where the walls are composed of the oxacalixarenes while the trans isomer 14 forms an assembly with irregularly shaped pores. Oxacalixarene 15 also assembles into an extended structure with tubular pores where the walls are composed of two trimeric arc-shaped assemblies that are bridged by the oxacalixarenes in different orientations. Zhang and Chen claim that the solid- state structure of 15 is hollow and makes no mention of included solvent, but examination of the CIF shows that all of the electron density that would be present within the voids due to the presumably disordered guest solvent has been removed.13 Weak C-H···π interactions are also responsible for the self-assembly of the molecular cage 16 into an extended structure when crystallized from dichloromethane/mesitylene, with solvent-filled voids resulting from the open structure of the cage (Figure 1.6d). The guest mesitylene molecules interact with the cages through similar C-H···π interactions.14  14 N N OO OO N N N N N N Cl OO OO Cl ClCl ClCl N N OO OO ClCl ClCl 13 14 15 16   15  Figure 1.6.  Solid-state extended structures (guest solvent removed for clarity) of (a) 13  (b) 14  (c) 15  (d) 16. 16  Stronger interactions such as hydrogen-bonding can also be used for the self- assembly of iptycenes into extended structures. The solid-state structure of triptycene diamide 17 shows both intramolecular and intermolecular hydrogen-bonding which causes it to adopt a folded conformation and produces a chain-like extended structure, respectively. Complementary π interactions between the triptycene phenyl rings on adjacent molecules of 17 brings them together to fill the void space in one of the triptycene clefts and links adjacent chains into pairs. The packing arrangement is affected by the crystallization solvent, as toluene is selectively included when grown from methanol/toluene, while crystals grown from methanol are solvent-free (Figure 1.7a). This pairing of triptycenes is present for all compounds in the series of modified triptycenes 18-22 with the exception of 21, demonstrating the importance of π interactions in iptycene-containing extended structures (Figure 1.7b-f). Triptycenes 18-22 also show that hydrogen-bonding is required for the formation of extended chains as these chains are not observed in 18 which does not have hydrogen-bonding moieties. All of these triptycenes except for 18 contain guest solvent in the lattice to fill the voids created by the free volume from the triptycene structure. Increasing the steric bulk imposed by the iptycene prevents pentiptycene diamide 23 from adopting a folded conformation like 17, but this compound is still able to assemble into an extended grid-like structure with channels containing guest methanol molecules (Figure 1.7g). This structure is not held together by hydrogen-bonding but is assembled through complementary π-stacking of the N-acetylsulfanilyls.15  17  O O S S NH NH O O O O OO 21 O O S S NH NH O O OO 20 O O    18  Figure 1.7.  Solid-state extended structures of (a) 17  (b) 18  (c) 19 (DMSO molecules shown in green)  (d) 20 (toluene molecules shown in green)  (e) 21 (methanol molecules shown in green)  (f) 22 (methanol molecules shown in green)  (g) 23 (methanol molecules shown in green). 19  Organometallic coordination can also be used to assemble triptycene into extended structures, as triptycene reacts with silver perchlorate in toluene to give [Ag3(triptycene)3(ClO4)3](toluene)2 (24, Figure 1.8a) with η2 hapticity. Both the triptycenes and the silver atoms have two different coordination motifs, resulting in a two-dimensional sheet, which is then linked together by perchlorates to form a three-dimensional network. The open network contains toluene molecules intercalated between the triptycene-silver sheets. Heating removed the guest solvent without the loss of crystallinity, but this process is not truly reversible since re-adsorption of toluene did not result in the same structure. The solvent and counterion used can alter the composition of the resulting silver-triptycene complex. Using THF produced [Ag(triptycene)(THF)2](ClO4) (25), which has a one- dimensional chain structure in which the silver atoms have two coordinated THF molecules and are bridged by triptycenes binding in an η1 mode. The perchlorates in 25 are non- coordinating and fill the voids between the chains (Figure 1.8b). Using silver triflate and toluene yields [Ag6(triptycene)4(CF3SO3)2(H2O)6](CF3SO3)4 (26) which is a two-dimensional sheet featuring both η1 and η2 coordination and where some silver ions are coordinated by aqua ligands. The sheets are then linked by triflates and waters to form a three-dimensional network, with the cavities filled by non-coordinating triflates (Figure 1.8c).16  20  Figure 1.8.  Solid-state extended structures of (a) 24  (b) 25  (b) 26.  Stronger metal-ligand coordination can also be used to generate porous extended structures incorporating triptycenes. Rieger and coworkers attempted to form metal-organic frameworks similar to MOF-5 by reacting 9,10-triptycenedicarboxylic acid (H227) with zinc nitrate in diethylformamide (DEF) under hydrothermal conditions. Two-dimensional (28) and three-dimensional (29) frameworks formed, depending on the Zn(NO3)2:H227 ratio or the reaction time (Figure 1.9). Framework 28 is composed of Zn2(27)4(DEF)2 four-bladed paddlewheels that are linked by the triptycenes to form sheets with a square-shaped motif. Framework 29 has three-bladed Zn2(27)3 paddlewheels that are joined together by thetriptycenes, although the coordination modes of the axial carboxylates in the paddlewheels are either through a single oxygen or through both oxygen atoms in a chelating manner. In 21 this framework, 51% of the volume is solvent-accessible through two types of channels, but unlike typical MOFs, drying 29 resulted in a loss of crystallinity.17  COO OOC 27  Figure 1.9.  Solid-state extended structures (solvent omitted for clarity) of (a) 28 and  (b) 29.  1.1.5 Host-guest chemistry  As discussed, the solid-state structures of iptycenes often have guests located in the clefts between the aromatic rings to fill the internal free volume. Guests can be bound in these clefts if they are capable of reasonably strong interactions with the phenyl rings. In 1998 Rathore and Kochi demonstrated that cationic radicals with the iptycene structure (30- 32) can reversibly bind a single molecule of nitric oxide, producing a distinct colour change from yellow to green or purple upon binding. A solid state structure of 32•+ shows that the NO binds within the cleft, interacting with one of the phenyl rings (Figure 1.10). These 22 interactions are sufficiently weak that NO was only tightly bound at -30 °C, although the binding was reversible over multiple heating and cooling cycles in a sealed system.18    Figure 1.10.  Solid-state structure of [32•+•NO][SbCl6]. Carbon, black; nitrogen, blue; oxygen, red; chlorine, green; antimony, pink.  Iptycenes were not used as hosts for reversible guest binding for another 7 years until Chen and coworkers used triptycene as a rigid scaffold to build hosts combining concave aromatic surfaces together with dibenzo-24-crown-8 ethers that are known to bind secondary dialkylammonium ions. This provides the potential for binding guests through π-interactions, electrostatic interactions, or a combination of both. The host molecule 33 with two triptycenes and a single crown ether was constructed as a receptor that would maximize the amount of π-interactions due to its high triptycene content. Indeed, 33 binds various viologen (N,N’-dialkyl-4,4’-bipyridinium salt) guests in a 1:1 host:guest ratio, and a solid-state 23 structure of complex 34 having bound methyl viologen shows that the charged nitrogens are not directed towards the crown ether but protrude from the cavity. This shows that the most significant host-guest interactions are not between the crown ether and the charged nitrogens, but are the π-interactions between the pyridinium rings and the cavity walls. Cyclic voltammetry provides additional confirmation for this observation, as the reversible reduction waves of the viologen guests shifted toward less negative potentials when complexed by 33, and dissociation of the host-guest complex occurred following a two- electron reduction. Association constants (Kassoc , determined by 1H NMR spectroscopy) for these assemblies are in the order of 103 (in 1:1 CDCl3/CD3CN). The solid-state structure of 34 also reveals two slightly different binding modes, one where the viologen is closer to the crown ether, and the other where the viologen is slightly further away from the crown ether, allowing additional π interactions with a phenyl ring at the other end of the cavity. There are also viologen molecules outside of the cavities that interact with the phenyl rings on the exterior of 33 through π interactions to link individual complexes together into a two- dimensional extended ribbon-like network (Figure 1.11).19    24  Figure 1.11.  Solid-state extended structure of 34 (guest solvent molecules and counterions omitted for clarity).  In the barrel-shaped host 35 having two triptycenes and two crown ethers, the host- guest interactions tend to favour involvement of the crown ethers. Viologens with alkyl chains of varying lengths were bound by 35 between the crown ethers to give 1:1 complexes as the distance between the crown ethers is optimal for binding. Kassoc values are on the order of 103 for viologens with longer chains while complex 36 having bound methyl viologen has a Kassoc of 105 (in 1:1 CDCl3/CD3CN). Solid-state structures confirm that the viologen is bound within the cavity with the ammonium cations interacting with the crown ethers and the octyl chains of the viologen guest in complex 37 are threaded through the crown ethers to form a pseudorotaxane (Figure 1.12). Guest binding is further stabilized by the presence of π- stacking between the triptycene aromatic rings and the viologen pyridinium rings, resulting in charge transfer interactions. Mixing host 35 and the guest viologens resulted in immediate and distinct colour changes, indicative of charge transfer.20 25     Figure 1.12.  Solid-state structures of (a) 36  (b) 37.  Charged species such as dibenzylammonium cations are also capable of threading through the crown ethers in 35 to give complex 38, where the guests are primarily bound by hydrogen bonding between the crown ethers and the ammonium cations, and are stabilized by π interactions with the triptycene aromatic rings inside the host cavity. In the solid state, 26 molecules of 38 are linked together into tubes by interactions with bridging PF6- counterions (Figure 1.13).21   Figure 1.13.  Solid-state structure of 38  (a) asymmetric unit and  (b) extended structure.  Changing the substituents on the viologen guests can alter their binding mode within the central cavity of 35. Guests bearing substituents other than alkyl chains are bound so that the pyridinium groups are not directed towards the crown ethers. Those with shorter hydroxyalkyl groups form complexes with a host:guest ratio of 1:2 with the hydroxyethyl groups pointing outside of the cavity (e.g. 39, Figure 1.14). Viologens with longer hydroxyalkyl groups or with other substituents bind in a 1:1 ratio along the inner periphery of the cavity through π-interactions with the triptycene aromatic rings, leaving void space in the remainder of the cavity. There is no penalty for favouring π-interactions, as Kassoc values for the formation of these complexes are still on the order of 103 (in 1:1 CDCl3/CD3CN).20  27  Figure 1.14.  Solid-state structure of 39.  Host 35 also has the ability to bind other planar, charged guests through π- interactions with the interior walls of the cavity as the addition of the diquat guests 40 and 41 results in 1:1 complexes 42 and 43, respectively. Solid-state structures show that whereas 41 is located in the centre of the cavity, the smaller 40 is bound along one side of the cavity and the remaining void space is filled by guest acetonitrile solvent molecules (Figure 1.15). This void space can be used to bind other uncharged, electron-rich guests to form a ternary charge-transfer complex containing one charged guest and another uncharged guest that is bound by π interactions.22    28  Figure 1.15.  Solid-state structures of (a) 42 and  (b) 43.  The ability of 35 to bind both linear and planar charged guests can be exploited to reversibly and controllably switch between ternary and binary complexes utilizing different guest binding modes. Addition of acid to the ternary complex containing the guest molecules 40 and 44 converted dianiline 44 to a diammonium. The preference of 35 to bind linear charged guests between the crown ethers leaves no room for 40, resulting in its expulsion to generate a binary complex. The original ternary complex was regenerated by the addition of base to deprotonate H244, favouring the binding of the uncharged guest 40 followed by binding of the neutral 44 (Scheme 1.2).22    29  Scheme 1.2.  Conversion between ternary and binary host-guest complexes using acid and base.  The triptycene-crown ether hosts are also capable of binding neutral, planar guests within the central cavity, though this requires the presence of alkali metal ions to provide bridging interactions between the host and the guest. Host 45, having a smaller cavity and an anthracene moiety to enhance the host-guest π interactions, behaves in a similar manner to 35, binding propyl viologen with the alkyl chains extruded through the crown ethers to the exterior. A solid-state structure shows that neutral guests such as pyromellitic diimide (46) are not bound in the cavity but are instead sandwiched between the anthracenes on the exterior of two host molecules, held there by π interactions (Figure 1.16a). Upon the addition of Li+ and K+, 46 and anthraquinone (47), respectively, were bound in the interior of 45 forming 1:1 charge-transfer complexes 48 and 49, respectively (Figure 1.16b-c). The heteroatoms in 46 and 47 interact with the alkali metals that are bound in the crown ether pockets, providing the additional interactions that favour their positioning within the central cavity. 30  NN O O O O O O 46 47 45 O O O O O O O O O O O O O O O O    Figure 1.16.  Solid-state structures of (a) 45•46  (b) 48  (c) 49. 31  The specific requirement for a particular alkali metal ion to be present for binding of a given neutral guest allows this system to be reversibly switched between the binding of the three guests by controlling the presence of the alkali metal ion. When Li+ was present 46 was bound, when K+ was present 47 was bound, and in the absence of either alkali metal ion, propyl viologen (50) was bound to form complex 51 (Scheme 1.3).23    48 49 51 Li+ K+ 18-crown-6 12-crown-4 46 47 46 18-crown-6 4712-crown-4 46 50 50 50 50 K+ Li+ 47 46  Scheme 1.3.  Three-way switching for guest binding by 45.  32 The use of alkali metal ions to control binding of neutral guests was used to synthesize a rotaxane through a threading and capping strategy, using host 35 as the macrocyclic component. Adding K+ allowed the anthraquinone-containing thread 52 to be bound within the cavity of 35 to generate a pseudorotaxane. Reaction of the azides on the ends of the threaded 52 with tert-butyl containing alkynes using Huisgen 1,3-dipolar cycloaddition installed bulky 1,2,3-triazole stoppers. Finally removal of K+ with 18-crown-6 yielded the desired rotaxane 53.24  O O 53 O O O O O O O O O O O O O O O O O O O O N N N N N N N N NN N N CO2tBu CO2tBu tBuO2C tBuO2C CO2tBu CO2tBu tBuO2C tBuO2C O O O O O O N3 N3 N3 N3 52  33 1.1.6 Molecular machinery  The rigid geometry of triptycene, with its three phenyl rings forming a three-bladed structure that can pivot around the C3 rotational axis passing through its bridgehead carbons, has inspired the use of iptycenes in molecular machines. Oki and coworkers have shown that free rotation of the triptycene around this axis occurs unless there are substituents with sufficient steric bulk present at the bridgehead. The energy barrier to rotation can also be altered by adding substituents to the phenyl rings; substituents at the alpha positions have the largest effect due to their proximity to the bridgeheads.25  Iwamura and Mislow applied these principles to create and study bis-triptycenes linked at the bridgeheads through a single atom, focusing on a methylene (54) or an ether (55) spacer. This places the two triptycenes in close proximity to each other and creates a molecule resembling a set of intermeshed three-toothed “molecular gears”. Solid-state structures of 54 and 55 show large deviations from the ideal bond angles, indicative of the steric strain that arises from the intermeshing (Figure 1.17). The lowest energy conformation of such systems has the phenyl rings staggered so that one ring lies in the cleft of the other triptycene. Since the rings cannot occupy the same space, rotation of the triptycenes must take place in opposite directions. From the various systems examined, the energy barrier to this rotary motion can be sufficiently low so that rotation occurs freely at room temperature on the NMR timescale. However, the presence of certain substituents on the rings increases this barrier so that the different isomers can be separated using HPLC. Conrotary motion has a significantly higher energy barrier as it involves an even greater distortion of the already distorted bond angles at the central spacer atom for the triptycenes to become sterically 34 decoupled.26,27   Figure 1.17.  Solid-state structures of (a) 54 and  (b) 55.  In 1994 Kelly and coworkers reported the first example of using iptycenes to make a functional molecular machine where the triptycene rotation could be controlled. Compound 56 has a 2,2’-bipyridyl group attached at the bridgehead and the terminal ring is able to adopt an orientation so that it does not interfere with the rotation of the triptycene. Addition of a divalent metal such as Hg2+ results in the coplanarization of the two pyridine rings to chelate the metal ion (57). The close proximity of this planar bipyridine to the triptycene moiety results in steric interference and halts its rotation, with only some slippage reported upon heating but with no rapid rotation observed. The brake was released and applied, switching between 57 and 56, by subsequent additions of EDTA and Hg2+, respectively (Scheme 1.4).28   Scheme 1.4.  Reversible actuation of a “molecular brake”.  To create useful molecular machines, subsequent work focused on achieving rotary 35 motion in a single direction; Kelly chose to attach a helicene to the triptycene as it creates a difference in energy barriers for rotation in different directions and these barriers are sufficiently high to prevent rotation at room temperature.29 However, the energy difference is insufficient for unidirectional motion, so the triptycene was modified with an amino group, and a propanol group was attached to the helicene (58). Addition of phosgene converts the amine to an isocyanate (59) and oscillation of the helicene within the cleft brings the end in close proximity to form a urethane (60). As this prevents the helicene from returning to the other side of the cleft, upon heating the helicene rotates past the triptycene phenyl ring into the next cleft where it remains at a lower energy state (61). Cleavage of the urethane link restores the original molecule but rotated 120° in a single direction (62), Scheme 1.5.30  O HO(H2C)3 NH2 O HO(H2C)3 N C O O N H C O O O H NC O O O HO(H2C)3 H2N 58 59 60 6162 Scheme 1.5.  Unidirectional rotation of a “molecular rotor”.  To create a rotor that will spin over 360°, 58 was modified so that there is an amino 36 group on each triptycene ring. In order to direct the isocyanate formation to the desired amine, a 4-(dimethylamino)pyridine (DMAP) group was also installed on the helicene. However, when the modified system (63) was treated with phosgene all three amines reacted as phosgene is too reactive for DMAP to mediate. Using the less reactive 1,1’- carbodiimidazole acylated only the desired amine, but the imidazole did not leave to generate the target isocyanate. To resolve this problem, the other amines were protected with trifluoroacetates and the imidazole was removed (64), allowing the free amine to be converted to the isocyanate using phosgene (65). Unfortunately, rotation did not occur because the DMAP interacted with the isocyanate to form a highly stable cyclic acyl pyridinium salt, preventing urethane formation.30    McGlinchey and coworkers have also investigated controlling the rotation of triptycenes through reversible chemical modifications, attaching an indenyl group to the triptycene bridgehead. The indenyl can be attached at either its 2- or 3-position, allowing its long axis to be oriented parallel or perpendicular, respectively, to the rotational axis. The less hindered 2-indenyl system (66) rotated freely at room temperature while rotation of the more 37 sterically hindered 3-indenyl system (67) was only observed upon heating. The indenyl was intended to serve as a location for the controlled binding of Cr(CO)3 to serve as a brake. Indeed, adding Cr(CO)3 to 66 leads to coordination of Cr(CO)3 by the 6-membered indenyl ring; this does not hinder rotation as the Cr(CO)3 group is far from the triptycene rotor. Deprotonation of the indenyl shifts the site of coordination to its 5-membered ring where the bulky Cr(CO)3 is able to halt rotation of the triptycene at room temperature.31    Compound 66 was also used to prepare a dimeric triptycene intermeshed gear (68), where the steric constraints were sufficiently severe that a solid-state structure shows significant distortion in the angles between the rings of the typically rigid triptycenes (Figure 1.18). But in solution the triptycenes were able to intermesh and freely undergo disrotatory motion on the NMR time scale.32  38  Figure 1.18.  Solid-state structure of 68.  1.1.7 Polymers  Polymers containing iptycenes were first reported in 1968, when the rigid triptycene- based diol 69 was incorporated into poly(ethyleneterephthalate)s, with a linear increase in the polymer’s glass transition temperature (Tg) versus the ratio of 69 used. However, substitution of the already rigid terephthalic acid with 9,10-triptycenedicarboxylic acid (H227) did not produce significant changes in the polymer properties. Other 9,10-disubstituted triptycene monomers (70-77) were also incorporated into a series of 15 different polymers including polyesters, polyurethanes, polyamides and a polyoxadiazole, in an effort to make the polymers rigid without using colour-inducing aromatic monomers. Most of these polymers had high melting points and decent thermal stabilities. The polyamides were insoluble in highly polar hydrogen-bonding solvents but were soluble in less polar non-hydrogen-bonding solvents due to the amides being sterically shielded by the triptycenes, preventing hydrogen- bonding interactions with the solvent. Although some of the polymers were colourless and could be processed into thin films by solution-casting, their usefulness was limited because their high crystallinity made them brittle or weak.33 39     For the next 29 years there was only limited work on iptycene-containing polymers until Yang and Swager prepared poly(phenyleneethynylene)s (PPEs) incorporating pentiptycenes (78) using Sonogashira Pd-catalyzed coupling. The steric bulk of the pentiptycenes prevents the typical problem associated with PPEs of π-stacking and excimer formation in the solid state, so there is no significant red shift in the absorption spectra of 78 going from solution to the solid state. Preventing π-stacking also greatly improved polymer solubility in organic solvents and the fluorescence quantum yield. Thin films of 78 demonstrated reversible, rapid, and highly sensitive detection of nitro-aromatic explosives such as TNT by fluorescence quenching (Figure 1.19), a result of the iptycenes producing a highly porous polymer with cavities allowing analyte vapours to efficiently penetrate the polymer and interact with the electron-rich backbone.34  40 OC14H29 C14H29O n 78   Figure 1.19.  Time-dependent fluorescence intensity and fluorescence quenching (inset) of 78 exposed to TNT vapour.  Reprinted with permission from reference 34a. © 1998, the American Chemical Society. Increasing the size of the iptycene is more effective at keeping the polymer backbone separated, as polymer 79 with only triptycene monomers had a significant redshift in its absorption going from solution to the solid state, characteristic of aggregation. Polymer 80 containing only iptycenes was expected to have a very large backbone segregation but unfortunately it was insoluble. However, the analogous poly(thiophenephenyleneethynylene) 81 was very soluble due to its non-linear shape and free rotation around the C-C triple bonds, combined with the presence of iptycenes. This demonstrates that while iptycenes can improve solubility by hindering close packing, they must be used in conjunction with flexible 41 elements that can provide a large number of degrees of freedom in order to render high molecular weight conjugated polymers soluble. To demonstrate this, random copolymer 82 with a high iptycene content is soluble.34  OC14H29 C14H29O n 79 n 80    Soluble PPEs combining alkoxy-substituted extended iptycenes with tetrafluorophenyl (83), pyridyl (84) and bipyridyl (85) groups have been reported, demonstrating the utility and wide scope of iptycene-containing PPEs. These polymers 42 showed no exciplex formation or ground state aggregation due to the iptycenes preventing interchain interactions.35   C12H25O OC12H25 N OC12H25 C12H25O n N 85  Poly(phenylenevinylene)s (PPVs) 86 and 87, prepared by Suzuki cross-coupling, showed an absorbance redshift in the solid state, again suggesting that iptycenes smaller than pentiptycene are not fully effective in preventing interchain interactions.  43   Other conjugated polymers containing larger iptycenes have also been synthesized, such as poly(phenylenebutadiynylene)s (PPDs) 88-90, which are similar to the original PPEs but are easier to prepare since homocoupling is used. These polymers are also similar in their solubility, lack of interchain interactions in the solid state, and exhibit fluorescence quenching when exposed to explosives vapours. Compared with PPEs, the PPDs have improved sensitivity but suffer from slower response times for exposure to and removal of the analyte. This behaviour is attributed to the larger cavities in the PPDs trapping and retaining the analyte molecules more effectively.36  C6H13O OC6H13 n OC6H13 C6H13O 89 C6H13O OC6H13 n C6H13O C6H13O 88 44   The internal free volume generated by the rigid iptycenes has been exploited to create microporous polymers with properties that make them useful as low-κ dielectric materials. Polymers 91 and 92 were formed by ring-opening olefin metathesis polymerization (ROMP), and increasing the internal free volume by having tert-butyl groups on the triptycenes (91b) produced the lowest dielectric constant of 2.59, with a surface area of around 400 m2 g-1 and a median pore diameter of 13.2 Å. On the other hand, polymer 92 doesn’t show any improvement over its triptycene-free analogue (93), as the attachment of the triptycene by a single bond gives the triptycene free motion and allows it to adopt a denser packing structure.    45 An alternative approach to producing polymers with low dielectric constants is to form poly(aryl ether)s (PAEs) 94 by the condensation of iptycene diols with decafluorobiphenyl. PAEs 94a, 94c and 94d have lower dielectric constants than polymer 91, with 94a having a dielectric constant of 2.41. Both the ROMP polymers and the PAEs are thermally stable and have high Tg values due to the presence of the rigid triptycenes, making them suitable for processing in the manufacture of devices. They are also not hygroscopic, ensuring that their performance as a dielectric will not degrade over time.37    An alternative approach to low-κ dielectric materials is to heat butadienes bearing iptycenes to form poly(butadiene)s 95-97 through thermally-initiated free radical polymerization. The dielectric constant of these polymers was estimated by measuring their refractive index; polymer 97 has the lowest refractive index, but 95 and 97 both have refractive indices similar to 91b and 94 suggesting that they have similarly low dielectric constants. Increasing the size of the acene wings in 96 was counterproductive as it resulted in poor solubility and low porosity arising from π-interactions between the naphthalenes on adjacent chains.37 46    Incorporating iptycenes into polyesters (98-100) has been used to simultaneously improve both their strength and ductility; these polymer properties are typically mutually exclusive. Compared to the reference polyester 101, the presence of triptycenes in 98-100 made these polymers less crystalline and decreased their melting points, but increased their Tg.    47 O O O O (CH2)10 O O O O x y n tButBu 100   A doubling in Young’s modulus and strength, combined with an increase of 14-21 times in the stress required to induce mechanical failure was also observed for polymers 98- 100 (Figure 1.20). These improved mechanical properties are due to the threading of the polymer chains through the triptycene cavities to fill the void space, and the decreased chain mobilities are responsible for the increased Tg. Under conditions of low strain the chains remain randomly oriented and since there are no strong interactions between the chains they can be easily untangled, primarily through the (CH2)10 units, enhancing ductility. Increasing the strain forces the polymer backbone into a fully extended conformation causing the chains to become interlocked, resulting in work hardening of the polymer as the applied force is distributed over the other chains. Although polyesters 99 and 100 have larger triptycenes and increased internal free volumes, they have worse mechanical properties than 98. This demonstrates that increasing the size of the triptycene cleft may not improve the polymer’s mechanical properties if doing so hinders access to the cleft and makes threading more difficult.38 48  Figure 1.20.  Stress-strain curves for (a) 98  (b) 99  (c) 100  (d) 101. D and WH signify drawing and work hardening regions, respectively.  Adapted with permission from reference 38b. © 2007, Wiley-VCH.  Iptycenes can also form tape-like polymers with very rigid backbones if the iptycenes are linked together directly or through rigid ladder-type linkages. Wudl and coworkers reported the insoluble, hyperbranched poly(iptycene) 103, prepared by the thermal decomposition of 2,3,9,10-tetrachloropentacene (102). Heating 102 to 350 °C results in the loss of chlorine and generates a benzyne, which undergoes a Diels-Alder addition to another molecule of 102, and repeated addition of these benzynes to pentacenes eventually results in 103 (Scheme 1.6). Further heating of 103 resulted in carbonization at the relatively low 49 temperature of 600 °C, generating a possibly graphitic material that had a conductivity of about 5 S cm-1.39   Scheme 1.6.  Formation of poly(iptycene) 103.  Swager and coworkers also synthesized a poly(iptycene) (105) through the Diels- Alder reaction of 104 as a monomer using high pressures to drive the reaction, but unlike 103, polymer 105 was soluble because there are long alkyl chains in each repeat unit (Scheme 1.7). Higher weight hyperbranched analogues of 105 were synthesized by including small amounts of monomers 106 and 107.  OMe OMe C8H17 C8H17 OMe MeO C8H17 C8H17 O n104 105 O  Scheme 1.7.  Formation of poly(iptycene) 105. 50   Mixing 105 into a poly(vinyl chloride) (PVC) host, causes the PVC chains to thread through the iptycene cavities to minimize the internal free volume. Subsequent stretching of the PVC host extended the PVC chains, causing the chains of 105 to align perpendicular to the PVC chains, forming a material resembling an interwoven molecular cloth (Figure 1.21).40   Figure 1.21.  Alignment of 105 using a stretched PVC matrix.  Reprinted with permission from reference 40a. © 2005, the American Chemical Society.  However, the backbone of 105 is not composed of pure iptycene units since the Diels- Alder reaction of 104 leaves epoxides in the resulting polymer. To deal with this, the 51 structurally related polymer 108 was synthesized under similar conditions and then dehydrated to yield the soluble all-iptycene polymer 109 (Scheme 1.8). Compared to monomeric model compound 110, 109 exhibited a substantial red shift in its absorption spectrum due to hyperconjugation between the acenes.40   Scheme 1.8.  Formation of poly(iptycene) 109.    Another notable iptycene-containing tape-like polymer was synthesized through the condensation of hexahydroxytriptycene 111 with dicyanotetrafluorobenzene 112 to yield the insoluble PAE ladder polymer 113 (Scheme 1.9). 52  Scheme 1.9.  Formation of polymer 113.  Gas adsorption studies indicated that 113 has pores in the sub nanometre range, demonstrating that the rigidity of triptycene is effective in enforcing a microporous structure. Polymer 113 was found to have a surface area of 1065 m2 g-1 and adsorbed 1.65% and 2.71% of H2 by weight at 1 and 10 atm, respectively, comparable to other microporous polymers (Figure 1.22).41   Figure 1.22.  H2 adsorption isotherms of polymer 113.  Reprinted with permission from reference 41. © 2007, the Royal Society of Chemistry. 53 1.1.8 Liquid crystals  Compounds that exhibit mesogenic, or liquid crystalline, properties are often composed of a rigid core and long flexible chains, as the rigid components pack together while the flexible chains prevent the formation of a completely ordered system. Iptycenes with long alkyl or alkoxy substituents would seem to be ideal candidates for liquid crystalline materials as the iptycene core is very rigid. However, there have only been two reports of iptycene-based mesogens thus far.  The first example was a triptycene bearing five long, flexible chains (114) that exhibited mesogenic behaviour at room temperature. At temperatures greater than 153 °C, further transitions to three other mesophases were observed; the highest temperature mesophase before the isotropic phase was identified as a smectic A mesophase. X-ray diffraction studies of the mesophases indicated that 114 packs into lamellar arrangements, with the triptycene cores in a hexagonal p31m arrangement within each layer and the long chains extending above and below the layer. A derivative with six long chains (115) is not liquid crystalline, possibly because there is less free space available for each chain, allowing the chains to adopt ordered conformations.42   54 A series of triptycenes bearing phenylethynyl groups, in a symmetrical (116) or unsymmetrical (117) manner, has also been reported to be liquid crystalline. Triptycenes 116 only exhibited nematic mesophases (e.g. 116c, Figure 1.23a) as the triptycenes pack in a head-to-tail manner to fill the internal free volume instead of into a lamellar phase like 114. Compounds 116 are liquid crystalline at room temperature, and increasing the length of the alkoxy chains decreased the phase transition temperatures. Mesophases were also observed for 117 upon cooling (e.g. 117c, Figure 1.23b), with the reduced symmetry inhibiting crystallization and allowing the mesophases to remain fluid over wide temperature ranges. Similarly, increasing the alkoxy chain length lowered the phase transition temperatures for 117.43  OR RO OR RO 116a R=C4H9 116b R=C6H13 116c R=C8H17 116d R=C10H21 116e R=C12H25 116f R=C14H29 116g R= 117a R=C6H13 117b R=C8H17 117c R=C10H21 117d R=C12H25 117e R=   55  Figure 1.23.  Marbled textures exhibited by (a) 116c and  (b) 117c on cooling.  Adapted with permission from reference 43. © 2002, the Royal Society of Chemistry.  While iptycenes have not seen widespread use as building blocks for mesogens, mesophases have been used successfully by Swager and coworkers to control the order and alignment of triptycene-based dopants in liquid crystalline matrices. When iptycenes are introduced into a liquid crystalline host, the mesogenic molecules fill the clefts between the phenyl rings to minimize the amount of internal free volume, just as when iptycenes are dissolved in typical solvents. If the mesogens are rod-shaped, they will prefer to thread lengthwise through the clefts as this arrangement would most effectively fill the free space while minimizing disruption of the surrounding host molecules. Aligning the mesogenic host will then force the guests to align in a similar manner, allowing control of guest alignment by standard liquid crystal orientational methods such by an applied electric field.  This strategy was demonstrated by doping 4-(trans-4-pentylcyclohexyl)-benzonitrile (5PCH), a common room temperature nematic liquid crystal, with triptycenes bearing anthracene groups (107 and 118). The anthracenes provided a means of tuning the aspect ratio (the ratio of a molecule’s long to short axes) as well as for determining the alignment using polarized UV-vis spectroscopy. Typically the long axis of the guests in liquid crystals 56 is aligned parallel with the direction of the host’s alignment, as was observed for anthracene in 5PCH. The opposite was observed for 107 and 118 as their long axes oriented perpendicular to the host’s alignment, showing that iptycenes can be used to induce unique orientations of solutes in a mesogenic host.3    The liquid crystals in modern LCD monitors are not the source of emission, only serving as a means of regulating the transmission of light by occlusion, so rapid switching of their orientation is an important consideration in developing new display technologies. Incorporating fluorescent dye molecules into a liquid crystalline host has the potential to generate light-emitting liquid crystalline displays. PPE trimers bearing different iptycenes (119-122) were added as blue fluorescent dyes to 5PCH. The presence of iptycenes in these rod-shaped molecules causes their long axes to align parallel to the direction of the host’s alignment. Increasing the number of triptycenes led to increased ordering but introducing pentiptycene inhibited ordering, as it is difficult for both clefts to be filled by a host liquid crystal molecule without disrupting the local order of the host. The suitability of this approach for producing actual devices was shown by controlling the orientation of dye 123, 57 composed of triptycenes attached to diaminoanthraquinone, which is commonly used in liquid crystal displays.    OC8H17 C8H17O NH 123 O O HN C8H17O OC8H17   However, the presence of triptycenes in 119-122 and 123 increase the switching times of the liquid crystalline host (Figure 1.24), especially if the triptycenes are located on the ends of the guest molecule (120 and 121) as it results in a greater deviation from the more easily reoriented cylindrical shape.44  58  Figure 1.24.  Optical switching response of 119 (dashed line is switching voltage, solid line is detector response).  Adapted with permission from reference 44. © 2002, the American Chemical Society.  The anisotropy of conjugated polymers bearing triptycenes, such as PPVs (124) and PPEs (125), can also be controlled. Firstly, it was found that the presence of triptycene was required to prevent interchain interactions leading to aggregation in order to make the polymers soluble in the liquid crystalline host 1-(trans-4-hexylcyclohexyl)-4- isothiocyanatobenzene (6CHBT). Similar to 119-122, 124 and 125 adopted conformations in which their long axes were oriented parallel to the direction of the host’s alignment due to the threading of the 6CHBT molecules through the triptycene clefts. The alignment also forced the polymers into highly extended conformations, increasing their effective conjugation lengths as seen by a red shift in their absorbance spectra.  59   PPEs bearing pentiptycenes (126) with terminal anthracenes were used to confirm the increase in the effective conjugation length upon polymer alignment. When the 6CHBT host doped with 126 was isotropic, the fluorescence originated from the polymer backbone; when the host was in an aligned nematic mesophase, however, the fluorescence originated from the terminal anthracenes due to improved intrachain exciton migration.45    Increasing the polymer chain length and molecular weight improves the polymer ordering, as seen in triptycene PPEs with ureidopyrimidone end groups (127). These end groups allowed 127 to self-assemble by hydrogen bonding into extended chains, producing elastomeric and gel materials. When 127 was introduced into aligned liquid-crystalline hosts, 60 a significant increase in its ordering was observed compared to its analogue with no hydrogen-bonding end groups. 46    An increase in ordering with increased polymer molecular weight was also observed for PPE 128. Although the presence of more triptycenes through increased polymer chain length improves ordering, a comparison of PPEs 128-130 shows that the presence of too many iptycenes per monomer hinders anisotropic ordering. If there is too much steric crowding present, this hinders the ability of the liquid crystalline host molecules to interact with the polymer and control its conformation and orientation.47  61 1.2 Goals and Scope of this Thesis  Early research on iptycenes mostly dealt with their preparation, when different synthetic routes to a wide range of iptycenes were developed. The recent focus has built upon these synthetic methodologies, using the rigid, shape-persistent nature of iptycenes for supramolecular and materials applications. Iptycenes have been successfully incorporated into solid-state assemblies, concave hosts, molecular machines, polymers, and liquid crystals with potential applications that take advantage of their novel properties. The high sensitivity and robust nature of polymer 78 has allowed it to be incorporated into detectors for explosive materials currently being fielded in harsh and demanding military environments including Iraq and Afghanistan. The iptycene-doped liquid crystal systems have been successfully converted into tunable lasing devices with desirable emission.48 Polymer 113 has been studied for its hydrogen adsorption properties, using the very high surface area granted by its intrinsic microporosity.  The field of iptycene-containing supramolecular systems is “opening up” as researchers exploit the unique properties of iptycenes including internal free volume, to develop new materials. It is likely that iptycenes will continue to be exploited for their intrinsic free volumes to produce novel highly porous polymers and supramolecular self- assemblies. However, most of these systems have been purely organic, without the presence of metals that can introduce properties such as magnetism and catalytic activity. Therefore the research projects in this thesis target the modification of triptycene to create rigid ligands that can be subsequently metallated to generate porous and stable metal-organic functional materials for applications such as guest exchange and gas storage. 62 The next chapter of this thesis will discuss the synthesis and characterization of the small molecule organic components that are required to construct the larger rigid molecules 131-135. In chapter 3, the synthesis and characterization of these phenazine-containing compounds is discussed, in particular the use of single crystal X-ray diffraction to further elucidate the ability of the iptycene structure to generate void space in the solid state. Chapter 4 demonstrates the use of these ligands to create highly stable and functional metal-organic frameworks that exhibit guest exchange properties from both solution and the vapour phase. In chapter 5, the creation of triptycene-based metal salphen complexes that possess intrinsic molecular porosity and their gas adsorption properties is discussed. Finally, the work carried out in this thesis is summarized in chapter 6 which concludes with a description of future prospects in this area of research.  N N 131 N N N N N N 132 N N 133  63 N N 134 N N N N N N 135   64 1.3 References  1. Bartlett, P. D.; Ryan, M. J.; Cohen, S. G. J. Am. Chem Soc. 1942, 64, 2649-2653. 2. Hart, H.; Shamouilian, S.; Takehira, Y. J. Org. 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Mater. 2005, 4, 383-387. 70 CHAPTER 2 TRIPTYCENYL AMINES AND QUINONES †  2.1 Introduction  In order to build larger triptycene-based molecules, it is necessary to develop an appropriate synthetic methodology to modify triptycene with specific, coupling-friendly functional groups to generate appropriate precursor components. The rigid phenazines targeted as part of the work in this thesis require triptycene-based o-phenylenediamines and o-quinones for their syntheses. These o-phenylenediamines are also needed for the synthesis of the metal salphens and other triptycene-based compounds discussed in this thesis. Therefore, it was necessary to prepare a library of triptycene-based amines and quinones having one, two, or three phenyl rings functionalized to serve as building blocks for further chemistry. Specifically, 2,3-diaminotriptycene (136), 2,3,6,7-tetraaminotriptycene (137), 2,3,6,7,14,15-hexaaminotriptycene (138), triptycenyl o-quinone (139), triptycenyl bis-o- quinone (140), and triptycenyl tris-o-quinone (141) are all desired components of this library.  † A version of this chapter has been accepted for publication. Chong, J.H. and MacLachlan, M.J. (2006) Robust Non-Interpenetrating Coordination Frameworks from New Shape- Persistent Building Blocks. Inorg. Chem. 45:1442-1444. 71 NH2 136 NH2 NH2 137 NH2 H2N H2N NH2 138 NH2 H2N H2N H2N NH2    When this work was initiated, the syntheses of 136 and 138 had been previously reported but they were not well-characterized.1 Also, it was necessary to devise accessible and optimized synthetic routes to these compounds.  2.2 Synthesis and Characterization of Aminotriptycenes  Amino groups are typically introduced onto aromatic rings by first introducing nitro groups that are then reduced to form the desired amines. Fortunately, prior kinetic studies of triptycene have shown that the desired beta positions are the most reactive towards electrophilic aromatic substitution.2 However, it is not possible to simultaneously introduce nitro groups at both the 2 and 3 positions since the first nitration strongly deactivates that particular ring toward further substitution, causing further nitration to take place on the unsubstituted rings. Therefore, the synthetic route to 136 requires a double nitration/reduction strategy (Scheme 2.1). 72  Scheme 2.1.  Synthetic route to 2,3-diaminotriptycene (136).  Introducing the initial nitro group does deactivate the other two rings slightly, but they still have reactivity comparable to unsubstituted triptycene.2 During the nitration reaction, the mono-nitrated triptycene 142 is also nitrated, albeit at a slower rate, resulting in unreacted starting material and undesired di-nitrated triptycenes 146. Attempts were made to optimize the reaction conditions to maximize the yield of the desired 142 and to minimize the amount of unreacted triptycene and 146. Table 2.1 shows the yields of the compounds from several reactions in which the stoichiometry of the nitrating agent was controlled by using the easily measured KNO3, converted to HNO3 in situ by p-toluenesulfonic acid. Adding more KNO3 reduced the amount of unreacted starting material but led to increased amounts of the undesired 146; the most desirable method was to use a stoichiometric equivalent of KNO3. However, it was subsequently found that using acetic acid as the solvent and concentrated nitric acid as the nitrating agent was the simplest method, as the reaction was complete after 6 hours of heating without significantly compromising the yield of 142. 73 Table 2.1.  Product distributions of nitrated triptycenes formed under varying reaction conditions.a  Adapted from “Synthesis and Structural Investigation of New Triptycene-Based Ligands: En Route to Shape-Persistent Dendrimers and Macrocycles with Large Free Volume” Chong, J. H.; MacLachlan, M. J. J. Org. Chem. 2007, 72, 8683-8690. KNO3 b Di-nitrated (146) c Mono-nitrated (142) c Triptycene c 1 9% 72% 19% 1.1 11% 72% 17% 1.2 14% 74% 12% a  All reactions were performed using 0.25 g of triptycene and 1.5 equivalents of p- toluenesulfonic acid in 10 mL of acetic anhydride, stirring overnight at room temperature. b  Equivalents of KNO3 added per equivalent of triptycene used. c  The ratio of products was determined by integration of their bridgehead signals in the 1H NMR spectra. Traces of tri-nitrated triptycenes evident were not integrated.  Compound 142 was difficult to purify by recrystallization and chromatography is not a suitable technique for large-scale syntheses because the high mobility of 142 on silica gel required dry loading techniques. It was preferable to first reduce the unpurified mixture of compounds and then to separate 143 from triptycene and diaminotriptycenes 147, as all these compounds have significant differences in their mobilities. In situ conversion of the amino group to a protected acetamide followed by selective nitration at the other beta position at low temperature with stoichiometric nitric acid (generated using KNO3 and p-toluenesulfonic acid) gave 144. Compound 144 was isolated as a yellow solid and the acetate protecting group was easily removed by basic hydrolysis to give 145 as an orange-yellow solid. The colours of 144 and 145 arise from the push-pull chromophore between the nitro and amino 74 groups. Reduction of 145 then afforded 136 as a moderately air-sensitive, white solid in good yield.  Compound 137 has not been reported in the literature, but an analogous synthetic strategy can be envisioned (Scheme 2.2). Unfortunately, multiple nitrations of triptycene leads to the formation of two isomers; in this case, 146a and 146b were formed in the statistical distribution of a 1:1 ratio. Fortunately, one of the reported procedures uses conditions in which the less soluble 146a precipitates out of solution and can be easily isolated by filtration.3 The filtrate contains a mixture of 146a and 146b that can be separated by chromatography, although this also involves dry loading due to their high mobilities on silica gel. Compounds 146a and 146b were then easily taken through the remainder of the synthetic route, in an analogous manner to the synthesis of 136, to yield 137 as an air- sensitive solid. It was fortuitous that 137 is insoluble in dichloromethane, allowing it to be purified by repeated washings that remove coloured impurities.  75  Scheme 2.2.  Synthetic route to 2,3,6,7-tetraaminotriptycene (137).  Compound 138 has been reported in the literature, prepared by nitration of trinitrotriptycene (45% yield) followed by reduction (Scheme 2.3).1 The low yield of the nitration is due to the formation of multiple byproducts resulting from substitution at the undesired alpha positions. Removing the byproducts is also problematic due to their chemical similarities, making them difficult to separate by recrystallization or by chromatography.  76  Scheme 2.3.  Literature synthesis of 2,3,6,7,14,15-hexaaminotriptycene (138).  To avoid these problems, 138 was synthesized by a sequential double nitration/ reduction route analogous to that used to prepare 136 and 137 (Scheme 2.4). Triptycene was easily tri-nitrated using concentrated HNO3 because the phenyl rings are sufficiently deactivated by the nitro substituents so that further nitration will only take place under more forcing conditions. However, this triple nitration led to a mixture of two isomers (150a and 150b) in an approximate ratio of 3:1 (150a:150b), confirming that the position of nitration is statistically controlled and that electronic effects are not significant. These isomers were difficult to separate by chromatography on a large scale, since dry loading was also required and they have similar Rf values. Since both compounds are suitable precursors to 138, it is possible to carry them through the entire synthetic route without intermediate purification, although this makes purification of the final product more difficult. Therefore it was preferable to reduce them to the corresponding amines (152) and separate the two isomers at 77 this stage by chromatography. Each triaminotriptycene isomer was then taken separately through the remainder of the synthetic route to 138. Compared with 136 and 137, 138 is the most air-sensitive since it has the greatest number of electron-donating amino groups that increase its susceptibility to oxidation. The insolubility of 138 in dichloromethane was also exploited to remove coloured impurities by trituration.   Scheme 2.4.  Synthetic route to 2,3,6,7,14,15-hexaaminotriptycene (138).  2.3 Synthesis and Characterization of Triptycene Quinones  The synthesis of some of the target phenazine-containing molecules requires the use of triptycenes with o-quinone moieties. Quinones are typically encountered as the stable para species since o-quinones are prone to dimerization through a Diels-Alder reaction. o- 78 Quinones have been isolated at low temperatures or by incorporating bulky substituents that prevent the close approach of two molecules in the orientation required for dimerization to take place. The rigid steric bulk imposed by the triptycene geometry should allow triptycene- based o-quinones to be stable at the elevated temperatures that are typically encountered during reactions. Compound 139 can be synthesized from the known 2,3-dibromotriptycene (155)4 in two or three steps, depending on the route chosen (Scheme 2.5).   Scheme 2.5.  Synthetic routes to triptycene o-quinone (139).  The bromine atoms in 155 were readily substituted with methoxy groups by an Ullman-type reaction to give 2,3-dimethoxytriptycene (156), and demethylation with boron tribromide yielded 2,3-dihydroxytriptycene (157). Compound 157 was easily oxidized using hydrogen peroxide and a catalytic amount of iodine to the desired 139.5 Quinone 139 is a deep red solid, similar to the parent o-benzoquinone.6 In air, 157 undergoes a very slow oxidation to 139, which was seen by the colourless 157 becoming pink and by the appearance of minor signals in its 1H NMR spectrum that correspond to the resonances for 139. Unlike 79 o-benzoquinone, 139 is indeed stable at ambient temperatures for months and can be recovered after heating to reflux overnight in ethanol or THF, confirming its suitability for use in further syntheses. An improved method for obtaining 139 was subsequently found, using cerium(IV) ammonium nitrate (CAN) to oxidatively deprotect 156, reducing the number of steps in the synthesis and improving the yield. Shortly after this work was done, an almost identical synthetic procedure was reported by Chen and coworkers who also used CAN to oxidize 156.7  A similar synthetic strategy can be conceived to obtain the desired bis-quinone 140 by oxidation of 158 with CAN (Scheme 2.6). Unfortunately, the reported synthesis of the required anthracene precursor for forming 158 involves 4 steps.8  OMe OMe O O158 140 MeO MeO O O CAN MeCN  Scheme 2.6.  Proposed synthetic route to triptycene bis-o-quinone (140).  Therefore, its methyl-substituted analogue (161) was targeted instead, since its synthetic route involves the known anthracene 159.9 Although the literature procedure employed to prepare 159 suffers from poor yields, it uses inexpensive starting materials and is amenable to scale-up. The diazonium 160 can also be formed on a large scale according to the literature, though this is complicated by it being a primary explosive that is friction- and heat-sensitive when dry.10 Heating 159 and 160 in 1,2-dichloroethane results in the decomposition of 160 to form benzyne in situ that can react as a dienophile with 159 in a 80 Diels-Alder reaction to yield the desired triptycene 161. Zong and Chen also reported the synthesis of 161 using the same synthetic strategy at around the same time.11 Subsequent treatment of 161 with an excess of CAN resulted in the desired bis-quinone 162, which was also a red coloured solid (Scheme 2.7).   Scheme 2.7.  Synthetic route to dimethyltriptycene bis-o-quinone (162).  Serendipitously, it was found that treating 161 with less than 4-5 equivalents of CAN resulted in selective oxidation of a single ring to give 163 (Scheme 2.8). This suggests that the oxidation takes place in a stepwise manner, which implies that the oxidation potential increases for each subsequent oxidation. This increase in oxidation potential is consistent with the previously observed electronic communication between the rings from orbital overlap.2  Scheme 2.8.  Synthetic route to dimethoxydimethyltriptycene bis-o-quinone (163).  81 A solid-state structure was obtained for 162 (Figure 2.1), which crystallized from toluene in the rhomobohedral space group R -3 c. Unlike many triptycene-based compounds, the molecules are close packed and there is no guest solvent present; the small size of the rings probably allows it to pack efficiently. Interestingly, the bridgehead carbons lie along a screw axis within the unit cell and an inversion centre also lies between them. This results in the molecules of 162 being crystallographically disordered, where a given molecule can occupy one of three overlapping orientations.   Figure 2.1.  ORTEP of 162. Ellipsoids are shown at the 50% probability level. Carbon, black; oxygen, red.  The interatomic bond lengths in 162 are very similar to those previously found for o- benzoquinone (Table 2.2). Unexpectedly, the quinone moieties do not appear to be completely planar as C5 and O1 show a slight deviation from planarity. This may be a result of the crystallographic disorder, but MacDonald and Trotter have reported that o- benzoquinone also exhibits a slight deviation from planarity.6 82 Table 2.2.  Bond lengths for quinone 162 and o-benzoquinone6.a  162 o-Benzoquinone C1-C2 1.530 C2-C3 1.529 C3-C4 1.360 1.341 C4-C5 1.442 1.469 C5-O1 1.223 1.220 a  All lengths are in Å.  A similar synthetic route to the tris-o-quinone 141 using CAN to oxidize hexamethoxytriptycene 165 was envisioned (Scheme 2.9). Instead of using a substituted benzyne and a substituted anthracene to form a substituted triptycene, triptycene itself was hexabrominated to give 164. This reaction was carried out by stirring triptycene in neat bromine with a catalytic amount of FeBr3; a high concentration of bromine is required as the bromination did not go to completion when a solvent was used. Compound 164 was then easily converted to 165 using similar Ullman-type conditions. However, treating 165 with CAN did not result in the desired product, but instead resulted in a poorly soluble red solid that 1H NMR spectroscopy revealed to be a mixture of compounds. 83  Scheme 2.9.  Proposed synthetic route to triptycene tris-o-quinone (141).  Since it is possible that the desired tris-quinone 141 suffers from poor solubility, the approach was modified to target tris-quinone 170 with methyl substituents at the bridgehead positions. Zhu and Chen had previously reported the synthesis of the hexamethoxytriptycene 169, formed by the addition of dimethoxybenzyne to 159.12 This method was attempted, but the yields were very low, and the dimethoxyanthranilic acid starting material was very air- sensitive and consequently difficult to work with. Therefore, a synthetic route similar to that used to form 165 was employed. Dimethyltriptycene (167) was synthesized by the addition of benzyne to the known 9,10-dimethylanthracene (166)13, followed by bromination under identical conditions using FeBr3 and excess Br2 to give 168. Compound 168 was also converted by the Ullman-type reaction to give the desired 169. However, treating 169 with CAN did not result in the desired quinone 170 (Scheme 2.10). Addition of CAN resulted in a solution with the typical red colour, indicative of o-quinone formation, but over the period of a couple of hours the colour slowly faded to give a pale yellow or colourless solution. The 84 colour changes observed indicates that 169 reacted with CAN to form at least one o-quinone moiety, but all the quinone moieties present subsequently decomposed or were converted to other functional groups. Unfortunately, the identities of the end products could not be determined.   Scheme 2.10.  Proposed synthetic route to dimethyltriptycene tris-o-quinone (170).  Based on the ability to oxidize 161 in a stepwise manner, attempts were made to partially oxidize 169. Indeed, these attempts were successful as both the mono-quinone 171 and the bis-quinone 172 were isolated, depending on the stoichiometry of CAN used (Scheme 2.11).  85  Scheme 2.11.  Synthetic route to mono-quinone 171 and bis-quinone 172.  However, addition of further amounts of CAN to 171 or 172 in attempts to form 170 resulted in the same gradual loss of colour. Since neither 171 or 172 could be recovered following the reactions, it is likely that the last o-dimethoxybenzene (veratrole) moiety was succesfully oxidized by CAN to form 170, but the product is unstable and undergoes decomposition. This decomposition must be rapid, since all attempts to isolate 170 using shorter reaction times or by carrying out the reaction at low temperatures were unsuccessful.  It is possible that 170 is unstable in the presence of CAN, so an alternative approach was employed to use milder oxidizing agents. Compared to veratrole-containing compounds, compounds with catechol moieties are easily oxidized due to the lack of a methyl protecting group, as seen by the slow spontaneous oxidation of 157 in air. Compound 169 was deprotected using the standard method of BBr3 to give 173 (Scheme 2.12), which also exhibits slow oxidation in air, slowly turning a pink colour. Oxidation of 173 using H2O2 and catalytic diphenyl diselenide in dichloromethane resulted in a black precipitate, which was found to be the mono-quinone 174.14 The oxidation may not have proceeded to completion because of the insolubility of these compounds in dichloromethane, but carrying out the reaction in acetonitrile also resulted in a loss of colour over time. 86  Scheme 2.12.  Proposed alternate synthetic route to tris-quinone 170 via 173.  Quinones 139, 162, and 163 were studied by cyclic voltammetry; their voltammograms all show reversible reductions (Figure 2.2). 87  Figure 2.2.  Cyclic voltammograms of triptycenyl quinones 139, 162 and 163 recorded in 0.1 M [(n-Bu)4N]PF6/THF solutions with a scan rate of 0.1 V s-1.  Quinones 139 and 163 show two one-electron reductions, where the first reductive wave around -0.7 V corresponds to the reduction to form the charged radical 175 or 176 and the second reduction at around -1.5 V generates the catecholate 177 or 178 (Scheme 2.13). The presence of two methoxy groups in 163 does not significantly affect the reductive potential.  88  Scheme 2.13.  Proposed mechanism for reduction of triptycenyl quinones 139 and 163.  The voltammogram for 162 is different, appearing to show two one-electron reductions and a single two-electron reduction. The first two reductive waves have very similar potentials, suggesting that they correspond to the same electrochemical process. These potentials are also similar to the first reductive wave of 139 and 163, which suggests that they also correspond to the formation of charged radical species, 179 and 180. The last reductive wave is similar in potential to the second reductive wave of 139 and 163, which suggests that both rings are oxidized simultaneously to generate the bis-catecholate derivative 181 (Scheme 2.14).   Scheme 2.14.  Proposed mechanism for reduction of triptycenyl quinone 162. 89 An article by Chen and coworkers describing the synthesis and characterization of 139, 162, 163, 171 and 172 was recently published, where dilute nitric acid was used instead of CAN to oxidatively deprotect the precursor veratrole derivatives.15 Chen’s group also performed cyclic voltammetry experiments on the quinones in dichloromethane, but he was only able to observe two-electron redox couples. The one-electron processes observed in this thesis are likely the result of using THF, which is more able to stabilize charged radical species. Chen also reports that attempts to synthesize 170 “did not succeed probably due to the lability of” 170, so no further work was performed as part of this thesis to obtain 170.  2.4 Conclusions  In summary, synthetic routes to a series of triptycene-based o-phenylenediamines and o- quinones were devised, and the properties of these compounds were determined. The air- sensitive phenylenediamines 136-138 were satisfactorily prepared using a double nitration/reduction strategy beginning with triptycene. Triptycenyl mono-quinone 139 and bis-quinone 162 were also obtained using cerium ammonium nitrate to oxidatively demethylate their triptycenyl veratrole precursors. However, attempts to obtain the tris- quinones 141 and 170 were unsuccessful due to their lack of stability. The electronic properties of quinones 139, 162 and 163 were studied by cyclic voltammetry and were found to have reversible reductions. An electrochemical mechanism was elucidated in which the reductions proceed in a stepwise manner with the formation of charged radical species through one-electron and two-electron reductions.  90 2.5 Experimental  2.5.1 General  Materials.  Compounds 1473, 1554, 1599, 16613 and 17312 were prepared according to literature procedures. Other reagents were obtained from standard suppliers. THF, DMSO, and dichloromethane were degassed by sparging the solvent with nitrogen before use.  Equipment.  1H and 13C NMR spectra were recorded on both Bruker AV-300 and AV-400 spectrometers. 13C NMR spectra were recorded using a proton decoupled pulse sequence. 1H NMR spectra were calibrated to the residual protonated solvent at δ 7.26 ppm, 2.05 ppm and 2.49 ppm in CDCl3, acetone-d6 and DMSO-d6, respectively. 13C NMR spectra were calibrated to the deuterated solvent at δ 77.00 ppm, 29.92 ppm and 39.52 ppm in CDCl3, acetone-d6 and DMSO-d6, respectively. HMBC pulse sequences were used to obtain the chemical shift of the carbon ipso to the nitro in compound 145.16 IR spectra were obtained using attenuated total reflectance with a Thermo Fisher Nicolet 6700 spectrometer or as KBr discs with a Bomems MB-series spectrometer. EI mass spectra were obtained using a double focusing mass spectrometer (Kratos MS-50) coupled with a MASPEC data system with EI operating conditions of: source temperatures 120-250 °C and ionization energy 70 eV. ESI mass spectra were obtained on a Waters/Micromass LCT time-of-flight mass spectrometer equipped with an electrospray ion source. Melting points were obtained on a Fisher-John’s melting point apparatus.  91 Cyclic voltammetry.  Cyclic voltammetry measurements were performed with an Autolab PGstat12 potentiostat in dry THF using a sealed glass three-electrode electrochemical cell. A silver wire (reference electrode), platinum wire (counter electrode), and platinum (working electrode) were used. The platinum working electrode surface was cleaned with acetone and dried with nitrogen before use. Potentials are referenced to the decamethylferrocene/decamethylferrocenium couple used as an internal standard. The measured half-wave potential (E1/2) for the decamethylferrocene/decamethylferrocenium internal standard is +0.66 V versus the reference electrode at a scan rate of 0.50 V s−1.  2.5.2 Procedures  Synthesis of 2-nitrotriptycene (142).  Concentrated nitric acid (12 mL) was added to triptycene (1.021 g, 4.02 mmol) in glacial acetic acid (30 mL) and the mixture was heated at 70 °C for 6 h. The cloudy yellow solution was cooled to room temperature, poured into 150 mL of water and stirred. The precipitate was collected by suction filtration and washed with water. Column chromatography on silica gel with 1:4 dichloromethane:hexanes yielded the product as a white solid (0.700 g, 58% yield).  Data for 142.  1H NMR (400 MHz, CDCl3) δ 8.20 (d, J=2 Hz, 1H, Ar), 7.91 (d of d, J=2,8 Hz, 1H, Ar), 7.48 (d, J=8 Hz, 1H, Ar), 7.42-7.39 (m, 4H, Ar), 7.05-7.02 (m, 4H, Ar), 5.53 (s, 1H, bridgehead), 5.52 (s, 1H, bridgehead) ppm.  13C NMR (100.6 MHz, CDCl3) δ 152.3, 146.9, 145.3, 143.9, 143.4, 125.73, 125.68, 123.91, 123.88, 123.8, 121.3, 118.6, 53.9, 53.7 ppm.  MS (EI, 70 eV) m/z 299 (M+).  IR ν (KBr) = 3092, 3068, 1519, 1459, 1341, 1194, 92 1166, 837, 751, 739, 629, 527 cm-1.  Mp. = 274-277 °C.  Anal. Calcd for C20H13NO2: C, 80.25; H, 4.38; N, 4.68. Found: C, 80.23; H, 4.42; N, 4.96.  Synthesis of 2-aminotriptycene (143).  To a solution of 142 (0.166 g, 0.55 mmol) in THF (30 mL) was added hydrazine monohydrate (0.5 mL) and a spatula tip of Raney nickel. After heating under nitrogen at 60 °C for 1.5 h until all the hydrazine was quenched, the mixture was cooled to room temperature. The solution was filtered through Celite and the solvent removed by rotary evaporation. Chromatography on silica gel with dichloromethane gave the product as a white solid (0.112 g, 75% yield).  Data for 143.  1H NMR (300 MHz, CDCl3) δ 7.32-7.30 (m, 4H, Ar), 7.11 (d, J=8 Hz, 1H, Ar), 6.98-6.95 (m, 4H, Ar), 6.76 (d, J=2Hz, 1H, Ar), 6.25 (d of d, J=2,8 Hz, 1H, Ar), 5.28 (s, 1H, bridgehead), 5.26 (s, 1H, bridgehead), 3.47 (br s, 2H, NH2) ppm.  13C NMR (75.4 MHz, CDCl3) δ 146.5, 145.9, 145.1, 143.7, 135.7, 125.0, 124.9, 124.0, 123.4, 123.2, 111.7, 110.8, 54.2, 53.2 ppm.  MS (EI, 70 eV) m/z 269 (M+).  IR ν (KBr) = 3468, 3379, 3204, 3064, 3039, 3015, 2960, 1619, 1581, 1491, 1472, 1457, 1334, 1189, 1156, 742, 619 cm-1.  Mp. = 246 °C (decomposes).  Anal. Calcd for C20H15.3NO0.15 (143•0.15 H2O): C, 88.30; H, 5.67; N, 5.15. Found: C, 88.15; H, 5.71; N, 5.37.  Synthesis of 2-acetamido-3-nitrotriptycene (144).  Acetic anhydride (50 mL) was added to 143 (1.303 g, 4.84 mmol), the mixture was stirred for 1 h, then p-toluenesulfonic acid monohydrate (1.045 g, 5.49 mmol) was added. The solution was cooled in an icebath and potassium nitrate (0.491 g, 4.86 mmol) was added. The icebath was removed and the solution 93 was stirred overnight at room temperature, resulting in a cloudy yellow-orange solution. Addition of the reaction mixture into 300 mL of water with stirring gave a yellow precipitate that was collected by suction filtration and washed with water (1.684 g, 98% yield).  Data for 144.  1H NMR (400 MHz, CDCl3) δ 10.48 (s, 1H, NH), 8.87 (s, 1H, Ar), 8.16 (s, 1H, Ar), 7.41-7.37 (m, 4H, Ar), 7.04-7.02 (m, 4H, Ar), 5.51 (s, 1H, bridgehead), 5.43 (s, 1H, bridgehead), 2.23 (s, 3H, CH3) ppm.  13C NMR (100.6 MHz, CDCl3) δ 169.0, 153.7, 143.9, 143.1, 140.2, 133.7, 132.6, 125.9, 125.8, 124.3, 123.8, 120.1, 117.0, 54.0, 52.9, 25.7 ppm. MS (EI, 70 eV) m/z 356 (M+).  IR ν (KBr) = 3338, 3066, 1701, 1629, 1584, 1492, 1473, 1460, 1335, 1254, 1221, 748, 626 cm-1.  Mp. = 244-247 °C.  Anal. Calcd for C22H16.3N2O3.15 (144•0.15 H2O): C, 73.59; H, 4.58; N, 7.80. Found: C, 73.46; H, 4.48; N, 8.12.  Synthesis of 2-amino-3-nitrotriptycene (145).  To a solution of 144 (2.677 g, 7.51 mmol) in ethanol (100 mL) was added water (2 mL) and sodium hydroxide (0.278 g, 6.95 mmol). The solution was refluxed for 5 h, cooled to room temperature and the solvent was removed by rotary evaporation. Flash chromatography on silica gel with dichloromethane followed by recrystallization from chloroform/hexanes yielded the product as a yellow solid (2.180 g, 92% yield).  Data for 145.  1H NMR (300 MHz, CDCl3) δ 8.03 (s, 1H, Ar), 7.40-7.33 (m, 4H, Ar), 7.07- 7.00 (m, 4H, Ar), 6.80 (s, 1H, Ar), 6.09 (s, 2H, NH2), 5.32 (s, 1H, bridgehead), 5.29 (s, 1H, bridgehead) ppm.  13C NMR (75.4 MHz, CDCl3) δ 152.8, 144.4, 143.8, 142.8, 133.9, 128.4, 126.0, 125.7, 123.9, 123.6, 120.0, 113.7, 53.6, 52.2 ppm.  MS (EI, 70 eV) m/z 314 (M+).  IR 94 ν (KBr) = 3490, 3377, 1642, 1584, 1499, 1459, 1420, 1314, 1249, 1188, 1158, 743, 627, 602 cm-1.  Mp. > 300 °C.  Anal. Calcd for C20H14N2O2: C, 76.42; H, 4.49; N, 8.91. Found: C, 76.10; H, 4.43; N, 9.30.  Synthesis of 2,3-diaminotriptycene (136).  To a solution of 145 (0.514 g, 1.64 mmol) in 100 mL THF was added hydrazine monohydrate (1.0 mL) and a scoopula tip of Raney nickel. After heating under nitrogen at 50 °C for 1 h until all the hydrazine was quenched, the solution was cooled to room temperature and filtered through Celite under nitrogen. The solvent was removed in vacuo and the product was isolated as a white solid (0.448 g, 92% yield).  Data for 136.  1H NMR (400 MHz, CDCl3) δ 7.33-7.30 (m, 4H, Ar), 6.96-6.93 (m, 4H, Ar), 6.78 (s, 2H, Ar), 5.23 (s, 2H, bridgehead), 3.20 (s, 4H, NH2) ppm.  13C NMR (100.6 MHz, CDCl3) δ 145.9, 137.6, 131.2, 124.9, 123.2, 113.2, 53.4 ppm.  MS (EI, 70 eV) m/z 284 (M+). IR ν (KBr) = 3398, 3322, 3063, 3037, 3016, 2952, 2924, 1626, 1594, 1499, 1470, 1457, 1339, 1308, 1189, 1156, 1064, 1023, 879, 860, 773, 736 cm-1.  Mp. = 250-253 ºC (decomposes).  Anal. Calcd for C20H16N2: C, 84.48; H, 5.67; N, 9.85. Found: C, 84.19; H, 5.60; N, 10.20.  Synthesis of 2,6-diacetamide-3,7-dinitrotriptycene (148a).  Acetic anhydride (25 mL) was added to 147a (0.557 g, 1.96 mmol), the mixture was stirred for 1 h, then p-toluenesulfonic acid monohydrate (0.862 g, 4.53 mmol) was added. The solution was cooled in an icebath and potassium nitrate (0.396 g, 3.92 mmol) was added. The icebath was removed and the 95 solution was stirred overnight at room temperature, resulting in a cloudy yellow solution. Addition of the reaction mixture into 150 mL of water with stirring gave a yellow precipitate that was collected by suction filtration and washed with water. Chromatography on silica gel with 1:19 ethyl acetate:dichloromethane yielded the desired product as a yellow solid (0.536 g, 60% yield).  Data for 148a.  1H NMR (400 MHz, CDCl3) δ 10.50 (s, 2H, NH), 8.93 (s, 2H, Ar), 8.22, (s, 2H, Ar), 7.44-7.42 (m, 2H, Ar), 7.11-7.09 (m, 2H, Ar), 5.55 (s, 2H, bridgehead), 2.26 (s, 6H, CH3) ppm.  13C NMR (75.4 MHz, CDCl3) δ 169.1, 152.0, 141.9, 138.0, 134.1, 132.9, 126.6, 124.4, 120.8, 117.2, 52.7, 25.7 ppm.  MS (EI, 70 eV) m/z 458 (M+).  IR ν = 3342, 1695, 1627, 1582, 1537, 1471, 1445, 1412, 1367, 1329, 1315, 1305, 1256, 1227, 1147, 1131, 1036, 998, 905, 869, 848, 751, 721, 660, 637, 581, 5334, 497 cm-1.  Mp. = 174-176 ºC.  Anal. Calcd for C24H18N4O6: C, 62.88; H, 3.96; N, 12.22. Found: C, 12.33; H, 4.20; N, 12.33.  Synthesis of 2,7-diacetamide-3,6-dinitrotriptycene (148b).  Acetic anhydride (50 mL) was added to 147b (1.748 g, 6.15 mmol), the mixture was stirred for 30 min, then p- toluenesulfonic acid monohydrate (2.68 g, 14.1 mmol) was added. The solution was cooled in an icebath and potassium nitrate (1.289 g, 12.75 mmol) was added. The icebath was removed and the solution was stirred overnight at room temperature, resulting in a slightly turbid red-brown solution. Addition of the reaction mixture into 300 mL of water with stirring gave a yellow precipitate that was collected by suction filtration and washed with water. Chromatography on silica gel with 1:9 ethyl acetate:dichloromethane yielded the desired product as an orange-brown solid (1.939 g, 69% yield). 96  Data for 148b.  1H NMR (300 MHz, CDCl3) δ 10.47 (s, 2H, NH), 8.94 (s, 2H, Ar), 8.21 (s, 2H, Ar), 7.46-7.40 (m, 2H, Ar), 7.12-7.09 (m, 2H, Ar), 5.63 (s, 1H, bridgehead), 5.49 (s, 1H, bridgehead), 2.26 (s, 6H, CH3) ppm.  13C NMR (100.6 MHz, CDCl3) δ 169.0, 151.3, 142.7, 141.1, 138.7, 133.9, 133.0, 126.6, 126.5, 124.9, 123.9, 120.3, 117.7, 53.8, 51.6, 25.6 ppm. HR-MS (EI, 70 eV) Calcd. for C24H18N4O4 (M+): 458.12263; Found: 458.12174.  IR ν = 3344, 1707, 1698, 1616, 1583, 1552, 1489, 1469, 1451, 1416, 1366, 1320, 1305, 1255, 1224, 1200, 1150, 1134, 1038, 992, 912, 902, 863, 847, 826, 758, 644, 663, 642, 612, 586, 558, 538, 525, 488 cm-1.  Mp. = 297-299 ºC.  Synthesis of 2,6-diamino-3,7-dinitrotriptycene (149a).  To a solution of 148a (6.981 g, 15.23 mmol) in ethanol (200 mL) was added sodium hydroxide (1.42 g, 35.5 mmol) and water (20 mL). The solution was refluxed for 2 h, cooled to room temperature, and the solvent was removed by rotary evaporation. The solid residue was suspended in water, collected by suction filtration and washed with water to give the desired product as an orange-yellow powder (5.585 g, 98% yield).  Data for 149a.  1H NMR (300 MHz, DMSO-d6) δ 7.98 (s, 2H, Ar), 7.55 (s, 4H, NH2), 7.43- 7.41 (m, 2H, Ar), 7.10-7.07 (m, 2H, Ar), 7.04 (s, 2H, Ar), 5.54 (s, 2H, bridgehead) ppm.  13C NMR (100.6 MHz, DMSO-d6) δ 151.5, 145.8, 142.7, 130.1, 126.7, 126.1, 123.9, 119.8, 113.7, 49.9 ppm.  HR-MS (EI, 70 eV) Calcd. for C20H14N4O4 (M+): 374.10151; Found: 374.10090.   IR ν (KBr) = 3469, 3359, 3325, 2961, 1646, 1590, 1573, 1493, 1456, 1417, 97 1391, 1318, 1239, 1169, 1152, 1135, 1100, 1022, 938, 901, 882, 849, 782, 766, 741, 712, 638, 610, 565 cm-1.  Mp. > 300 ºC.  Synthesis of 2,7-diamino-3,6-dinitrotriptycene (149b).  To a solution of 148b (0.513 g, 1.12 mmol) in ethanol (25 mL) was added sodium hydroxide (0.115 g, 2.88 mmol) and water (2 mL). The solution was refluxed for 1.5 h, cooled to room temperature, and the solvent was removed by rotary evaporation. The solid residue was suspended in water, collected by suction filtration and washed with water to give the desired product as an orange powder (0.371 g, 89% yield).  Data for 149b.  1H NMR (400 MHz, DMSO-d6) δ 7.91 (s, 2H, Ar), 7.52 (s, 4H, NH2), 7.47- 7.45 (m, 1H, Ar), 7.40-7.38 (m, 1H, Ar), 7.09-7.07 (m, 4H, Ar), 5.55 (s, 1H, bridgehead), 5.53 (s, 1H, bridgehead) ppm.  13C NMR (100.6 MHz, DMSO-d6) δ 150.4, 145.5, 144.2, 141.3, 131.5, 126.8, 125.8, 124.4, 123.5, 119.0, 114.3, 51.4, 48.6 ppm.  HR-MS (EI, 70 eV) Calcd. for C20H14N4O4 (M+): 374.10151; Found: 374.10199.  IR ν (KBr) = 3463, 3350, 2959, 1636, 1601, 1573, 1494, 1455, 1424, 1392, 1316, 1238, 1175, 1150, 1132, 899, 874, 839, 802, 783, 764, 750, 732, 713, 650, 619, 596, 569, 526 cm-1.  Mp. > 300 ºC.  Synthesis of 2,3,6,7-tetraaminotriptycene (137).  To a solution of 149 (1.638 g, 4.38 mmol) in THF (100 mL) was added hydrazine monohydrate (3 mL) and a spatula tip of Raney nickel. After heating under nitrogen at 65 °C overnight, the solution was cooled to room temperature and the solvent was removed in vacuo. DMSO was added to the residue and the solution was filtered through Celite under nitrogen. Dichloromethane was added to the 98 filtrate, resulting in a white precipitate. The supernatant was removed with a cannula and the precipitate was washed with dichloromethane. Vacuum drying yielded the desired product as an air-sensitive light grey solid (0.862 g, 63% yield).  Data for 137.  1H NMR (400 MHz, DMSO-d6) δ 7.21-7.19 (m, 2H, Ar), 6.85-6.83 (m, 2H, Ar), 6.56 (s, 4H, Ar), 4.88 (s, 2H, NH2) ppm.  13C NMR (100.6 MHz, DMSO-d6) δ 147.6, 135.8, 130.3, 123.7, 122.1, 111.2, 51.7 ppm.  HR-MS (EI, 70 eV) Calcd. for C20H18N4 (M+): 314.15315; Found: 314.15342.  IR ν (KBr) = 3390, 3318, 1633, 1587, 1486, 1465, 1456, 1446, 1335, 1309, 1196, 1184, 1057, 881, 769, 758, 735, 684, 654, 624, 605, 466, 436 cm-1. Mp. = 155-158 ºC (decomposes).  Synthesis of 2,6,14-trinitrotriptycene (150a) and 2,7,14-trinitrotriptycene (150b). Concentrated nitric acid (45 mL) was added to triptycene (2.339 g, 9.20 mmol) and the mixture was heated at 75 ºC for 4 h. The cloudy yellow solution was cooled to room temperature, poured into 200 mL of water and stirred. The precipitate was collected by suction filtration and washed with water. Chromatography on silica gel eluting with 1:3 ethyl acetate:hexanes followed by 1:1 ethyl acetate:hexanes gave 150a (2.750 g, 77%) as a pale yellow solid and 150b (0.748 g, 21% yield) as an off-white solid, respectively.  Data for 150a.  1H NMR (400 MHz, CDCl3) δ 8.31 (s, 3H, Ar), 8.04-8.02 (m, 3H, Ar), 7.64- 7.61 (m, 3H, Ar), 5.82 (s, 1H, bridgehead), 5.81 (s, 1H, bridgehead) ppm.  13C NMR (100.6 MHz, CDCl3) δ 149.6, 149.2, 146.21, 146.19, 144.3, 143.9, 125.0, 122.54, 122.50, 119.61, 119.58, 53.3, 53.2 ppm.  Mp. = 173-176 °C. 99  Data for 150b.  1H NMR (300 MHz, CDCl3) δ 8.34 (d, J=2 Hz, 3H, Ar), 8.05 (d of d, J=2,8 Hz, 3H, Ar), 7.62 (d, J=8 Hz, 3H, Ar), 5.84 (s, 1H, bridgehead), 5.80 (s, 1H, bridgehead) ppm.  13C NMR (100.6 MHz, CDCl3) δ 148.8, 146.2, 144.7, 125.0, 122.5, 119.5, 53.5, 53.1 ppm.  MS (EI, 70 eV) m/z 389 (M+).  IR ν = 3091, 1600, 1515, 1457, 1427, 1335, 1288, 1268, 1196, 1167, 1131, 1114, 1069, 973, 955, 901, 888, 867, 845, 822, 793, 770, 748, 735, 655, 616, 561, 539, 510, 492 cm-1.  Mp. >300 °C.  Anal. Calcd for C20H11N3O6: C, 61.70; H, 2.85; N, 10.79. Found: C, 61.72; H, 2.86; N, 10.86.  Synthesis of 2,6,14-triaminotriptycene (152a).  To a solution of 150a (10.837 g, 27.84 mmol) in THF (150 mL) was added hydrazine monohydrate (8 mL, 165 mmol) and a scoopula tip of Raney nickel. After heating under nitrogen at 60 °C for 6 h until all the hydrazine was quenched, the mixture was cooled to room temperature. The solution was filtered through Celite and the solvent removed by rotary evaporation to give the product as a yellow-orange solid (7.750g, 93% yield).  Data for 152a.  1H NMR (400 MHz, CDCl3) δ 7.04 (d, 3H, Ar), 6.69 (s, 3H, Ar), 6.24-6.20 (m, 3H, Ar), 5.02 (s, 1H, bridgehead), 5.00 (s, 1H, bridgehead), 3.45 (s, 6H, NH2) ppm.  13C NMR (100.6 MHz, CDCl3) δ 147.8, 147.0, 143.7, 143.6, 136.4, 135.6, 123.8, 123.6, 111.5, 111.2, 110.6, 110.4, 53.4, 52.4 ppm.  MS (EI, 70 eV) m/z 299 (M+).  IR ν (KBr) = 6418, 3366, 3005, 2949, 2923, 1625, 1479, 1330, 1296, 1262, 1189, 1139, 1117, 834, 773, 698, 576, 503 cm-1.  Mp. = 279-283 °C (decomposes).  100 Synthesis of 2,7,14-triaminotriptycene (152b).  To a solution of 150b (0.748 g, 1.92 mmol) in THF (80 mL) was added hydrazine monohydrate (2 mL, 41 mmol) and a scoopula tip of Raney nickel. After heating under nitrogen at 80 °C for 1.5 h until all the hydrazine was quenched, the mixture was cooled to room temperature. The solution was filtered through Celite and the solvent removed by rotary evaporation. The solid residue was dissolved in a small amount of THF, hexanes was added, and the resulting precipitate was collected by suction filtration and washed with hexanes. Vacuum drying gave the desired product as a pale yellow solid (0.507 g, 88% yield).  Data for 152b.  1H NMR (300 MHz, CDCl3) δ 7.05 (d, J=8 Hz, 3H, Ar), 6.73 (d, J=2 Hz, 3H, Ar), 6.25 (d of d, J=2,8 Hz, 3H, Ar), 5.07 (s, 1H, bridgehead), 5.00 (s, 1H, bridgehead), 3.46 (broad s, 6H, NH2) ppm.  13C NMR (100.6 MHz, CDCl3) δ 146.3, 143.4, 137.3, 123.3, 111.7, 110.8, 54.4, 51.4 ppm.  HR-MS (EI, 70 eV) Calcd. for C20H17N3: 299.14225; Found: 299.14202.  IR ν = 3431, 3355, 3205, 3007, 2945, 1614, 1586, 1496, 1478, 1450, 1327, 1297, 1267, 1183, 1143, 1117, 1095, 864, 837, 797, 773, 667, 578, 514, 450 cm-1.  Mp. = 271-275 °C (decomposes).  Synthesis of 2,6,14-triacetamide-3,7,15-trinitrotriptycene (153a).  Acetic anhydride (50 mL) was added to compound 152a (0.863 g, 2.88 mmol), the mixture was stirred for 30 min, then p-toluenesulfonic acid monohydrate (1.822 g, 9.58 mmol) was added. The solution was cooled in an icebath and potassium nitrate (0.879 g, 8.70 mmol) was added. The icebath was removed and the solution was stirred overnight at room temperature, resulting in a cloudy yellow-orange solution. Addition of the reaction mixture into 350 mL of water gave a yellow 101 precipitate that was collected by suction filtration and washed with water. The solid was chromatographed on silica gel with 1:19 ethyl acetate:dichloromethane to yield the product as a yellow solid (0.745 g, 46% yield).  Data for 153a.  1H NMR (400 MHz, CDCl3) δ 10.46 (s, 1H, NH), 10.43 (s, 2H, NH), 8.94 (s, 3H, Ar), 8.24 (s, 1H, Ar), 8.22 (s, 2H, Ar), 5.65 (s, 1H, bridgehead), 5.57 (s, 1H, bridgehead) ppm.  13C NMR (100.6 MHz, CDCl3) δ 169.2, 169.1, 150.5, 149.9, 136.6, 135.9, 134.5, 134.39, 133.35, 133.29, 121.6, 121.1, 117.9, 117.5, 52.6, 51.5, 25.69, 25.67 ppm.  MS (EI, 70 eV) m/z 560 (M+).  IR ν (KBr) = 3368, 1702, 1585, 1482, 1333, 1312, 1259, 1231, 1137, 1038, 868 cm-1.  Mp. =  244-247 °C.  Anal. Calcd for C26H20N6O9: C, 55.72; H, 3.60; N, 14.99. Found: C, 55.42; H, 3.82; N, 14.69.  Synthesis of 2,7,14-triacetamide-3,6,15-trinitrotriptycene (153b).  Acetic anhydride (40 mL) was added to compound 152b (0.514 g, 1.72 mmol), the mixture was stirred for 1 h, then p-toluenesulfonic acid monohydrate (1.18 g, 6.20 mmol) was added. The solution was cooled in an icebath and potassium nitrate (0.522 g, 5.16 mmol) was added. The icebath was removed and the solution was stirred overnight at room temperature, resulting in a cloudy yellow-orange solution. Addition of the reaction mixture into 200 mL of water gave a yellow-orange precipitate that was collected by suction filtration and washed with water. The solid was flash chromatographed on silica gel with 1:9 acetone:dichloromethane to yield the product as a yellow solid (0.750 g, 78% yield).  102 Data for 153b.  1H NMR (300 MHz, CDCl3) δ 10.43 (s, 3H, NH), 8.98 (s, 3H, Ar), 8.23 (s, 3H, Ar), 5.72 (s, 1H, bridgehead), 5.54 (s, 1H, bridgehead), 2.27 (s, 9H, CH3) ppm.  13C NMR (100.6 MHz, CDCl3) δ 169.0, 149.3, 137.3, 134.3, 133.4, 120.6, 118.4, 53.7, 50.4, 25.6 ppm.  HR-MS (EI, 70 eV) Calcd. for C26H20N6O9: 560.12918; Found: 560.12887.  IR ν = 3350, 1695, 1620, 1586, 1537, 1494, 1472, 1455, 1417, 1366, 1328, 1311, 1255, 1221, 1138, 1037, 997, 909, 857, 827, 763, 748, 664, 588, 545, 487 cm-1.  Mp. = 219-222 °C.  Synthesis of 2,6,14-triamino-3,7,15-trinitrotriptycene (154a).  To a solution of compound 153a (0.360 g, 0.64 mmol) in ethanol (50 mL) was added sodium hydroxide (0.125 g, 3.13 mmol) and water (2 mL). The solution was refluxed for 2 h, cooled to room temperature and the solvent was removed from the orange solution by rotary evaporation. After 80 mL of water was added to the residue, the solid was collected by suction filtration and washed with water. Recrystallization from acetone/chloroform gave the product as an orange solid (0.257 g, 92% yield).  Data for 154a.  1H NMR (400 MHz, acetone-d6) δ 8.06 (s, 3H, Ar), 7.19 (s, 3H, Ar), 7.16 (s, 6H, NH2), 5.54 (s, 1H, bridgehead), 5.53 (s, 1H , bridgehead) ppm.  13C NMR (100.6 MHz, acetone-d6) δ 152.4, 151.2, 146.9, 146.6, 131.4, 130.0, 129.4, 129.2, 121.5, 121.0, 115.3, 114.7, 51.7, 50.3 ppm.  MS (EI, 70 eV) m/z 434 (M+).  IR ν (KBr) = 3481, 3365, 2966, 1652, 1640, 1594, 1572, 1498, 1458, 1418, 1394, 1318, 1249, 1175, 1143, 1103, 894, 852, 766 cm-1.  Mp. > 300 °C.  Anal. Calcd for C20H16N6O7 (154a•H2O): C, 53.10; H, 3.56; N, 18.58. Found: C, 53.48; H, 3.33; N, 18.62.  103 Synthesis of 2,7,14-triamino-3,6,15-trinitrotriptycene (154b).  To a solution of compound 153b (0.746 g, 1.33 mmol) in ethanol (30 mL) was added sodium hydroxide (0.236 g, 5.90 mmol) and water (3 mL). The solution was refluxed for 2 h, cooled to room temperature and the solvent was removed from the orange solution by rotary evaporation. After 70 mL of water was added to the residue, the solid was collected by suction filtration and washed with water to give the desired product as an orange solid (0.515 g, 89% yield).  Data for 154b.  1H NMR (400 MHz, DMSO-d6) δ 7.90 (s, 3H, Ar), 7.53 (s, 6H, NH2), 7.10 (s, 3H, Ar), 5.55 (s, 1H, bridgehead), 5.47 (s, 1H, bridgehead) ppm.  13C NMR (100.6 MHz, DMSO-d6) δ 148.7, 145.5, 130.9, 127.3, 118.9, 114.8, 50.8, 46.8 ppm.  HR-MS (EI, 70 eV) Calcd. for C20H16N6O6: 434.09748; Found: 434.09675.  IR ν = 3471, 3360, 1633, 1574, 1494, 1426, 1387, 1315, 1241, 1201, 1143, 1040, 898, 875, 852, 839, 819, 799, 764, 732, 678, 654, 614, 585 cm-1.  Mp. > 300 °C.  Synthesis of 2,3,6,7,14,15-hexaaminotriptycene (138).  To a solution of 154 (2.110 g, 4.86 mmol) in THF (250 mL) was added hydrazine monohydrate (6 mL) and a scoopula tip of Raney nickel. After heating under nitrogen at 55 °C for 4 h until all the hydrazine was quenched, the solution was cooled to room temperature and the solvent was removed in vacuo. DMSO was added to the residue and the solution was filtered through Celite under nitrogen. Dichloromethane was added to the filtrate, resulting in a white precipitate. The supernatant was removed with a cannula and the precipitate was washed with dichloromethane. Vacuum drying yielded the desired product as an air-sensitive off-white solid (0.884 g, 53% yield). 104  Data for 138.  1H NMR (400 MHz, acetone-d6) δ 6.62 (s, 6H, Ar), 4.72 (s, 2H, bridgehead), 3.76 (s, 12H, NH2) ppm.  MS (EI, 70 eV) m/z 344 (M+).  IR ν (KBr) = 3384, 3310, 3006, 2941, 2851, 1634, 1590, 1481, 1444, 1335, 1297, 1193, 1046, 881, 844, 814, 787, 747, 710 cm-1.  Mp. = 181-184 °C (decomposes).  Synthesis of 2,3-dimethoxytriptycene (156).  A mixture of 155 (1.000 g, 2.44 mmol), copper(I) bromide (0.079 g, 0.55 mmol), 25 weight% sodium methoxide in methanol (5 mL, 22 mmol),  ethyl acetate (0.5 mL), and toluene (10 mL) was refluxed under nitrogen overnight. The solution was cooled, then quenched with the addition of water. After extracting the aqueous layer with dichloromethane, the combined organic layers were dried over anhydrous magnesium sulfate and filtered. The solvent was removed by rotary evaporation to give the desired product as a white solid (0.652 g, 85% yield).  Data for 156.17  1H NMR (300 MHz, CDCl3) δ 7.38-7.34 (m, 4H, Ar), 7.01 (s, 2H, Ar), 6.99- 6.95 (m, 4H, Ar), 5.33 (s, 2H, bridgehead), 3.82 (s, 6H, OCH3) ppm.  Synthesis of 2,3-dihydroxytriptycene (157).  To a solution of 156 (0.985 g, 3.13 mmol) in dry dichloromethane (100 mL) in an icebath was added boron tribromide (1 mL). The solution was stirred overnight under nitrogen and allowed to warm slowly to room temperature. The solution was poured into 100 mL of water, followed by the addition of concentrated hydrochloric acid (5 mL). The layers were separated and the aqueous layer was extracted with dichloromethane. After drying the combined organic layers over anhydrous 105 sodium sulfate, the solution was filtered and the solvent was removed by rotary evaporation to give a light grey solid. Recrystallization from chloroform yielded the desired product as fine colourless needles (0.470 g, 52% yield).  Data for 157. 17  1H NMR (300 MHz, CDCl3) δ 7.33-7.31 (m, 4H, Ar), 6.97-6.94 (m, 4H, Ar), 6.92 (s, 2H, Ar), 5.26 (s, 2H, bridgehead), 4.81 (s, 2H, OH) ppm.  Synthesis of triptycene o-quinone (139). Method 1:  To a solution of 157 (0.716 g, 2.50 mmol) in methanol (20 mL) was added iodine (0.046 g, 0.18 mmol) and concentrated sulfuric acid (0.15 mL). 30% hydrogen peroxide (3 mL, 26 mmol) was added dropwise and a red precipitate formed after addition was complete. The reaction was stirred for 4.5 h, then the precipitate was collected by suction filtration, washed with methanol, and recrystallized from chloroform/ethanol to give the desired product as a red solid (0.467 g, 66% yield). Method 2:  To a solution of 156 (5.683 g, 18.08 mmol) in acetonitrile (60 mL) was added a solution of CAN (29.69 g, 54.16 mmol) in water (30 mL), producing an immediate colour change to a dark blue colour, followed by a rapid change to a cloudy red colour. The solution was stirred for 3 h, then 100 mL of water was added, the precipitate was collected by suction filtration, washed with water and dried to yield the desired product as a red powder (4.693 g, 91% yield).  Data for 139.7  1H NMR (300 MHz, CDCl3) δ 7.42-7.40 (m, 4H, Ar), 7.26-7.25 (m, 4H, Ar), 6.33 (s, 2H, Ar), 5.12 (s, 2H, bridgehead) ppm. 106  Synthesis of 2,3,6,7-tetramethoxy-9,10-dimethyltriptycene (161).  To a solution of anthranilic acid (2.748 g, 20.04 mmol) and trichloroacetic acid (0.035 g, 0.21 mmol) in THF (20 mL) cooled in an icebath was added isoamyl nitrite (3.5 mL, 26 mmol) dropwise over ca. 1 min. The solution was stirred at room temperature for 1 h, then cooled in an icebath. The precipitate was collected by suction filtration, washed with cold THF and 1,2-dichloroethane, but was left slightly moist to give the diazonium 160 as a tan solid. CAUTION!! Compound 160 is shock- and heat-sensitive when dry and is known to decompose explosively!! Compound 160 was added without delay to a solution of 159 (3.214 g, 9.85 mmol) in dry 1,2-dichloroethane (70 mL) and the mixture was heated under nitrogen, resulting in the evolution of gas and a dark brown solution. After the solution was refluxed under nitrogen overnight and cooled to room temperature, the solvent was removed by rotary evaporation. The solid residue was suspended in methanol, collected by suction filtration and washed with methanol to remove the majority of the brown colour. Recrystallization from ethanol yielded the desired compound as an off-white powder (2.571 g, 65% yield).  Data for 161.11  1H NMR (300 MHz, CDCl3) δ 7.31-7.28 (m, 2H, Ar), 7.00-6.97 (m, 2H, Ar), 6.92 (s, 4H, Ar), 3.82 (s, 12H, OCH3), 2.37 (s, 6H, CH3) ppm.  Synthesis of 9,10-dimethyltriptycene bis-o-quinone (162).  To a suspension of 161 (0.504 g, 1.25 mmol) in acetonitrile (20 mL) was added a solution of CAN (3.036 g, 5.54 mmol) in water (10 mL), producing an immediate colour change to a dark blue colour, followed by a 107 rapid change to a red-brown colour. After stirring the solution for 1 h, the precipitate was collected by suction filtration, washed with water and dried to yield the desired product as a dark brown-red solid (0.386 g, 90% yield).  Data for 162.15  1H NMR (400 MHz, CDCl3) δ 7.49-7.47 (m, 2H, Ar), 7.38-7.36 (m, 2H, Ar), 6.34 (s, 4H, Ar), 2.03 (s, 6H, CH3) ppm.  Synthesis of 2,3-dimethoxy-9,10-dimethyltriptycene o-quinone (163).  To a suspension of 161 (0.201 g, 0.50 mmol) in acetonitrile (10 mL) was added a solution of CAN (0.683 g, 1.25 mmol) in 5 mL of water, resulting in an immediate colour change to a dark blue colour, followed by a rapid change to a red-brown colour. After stirring the solution for 1 h, 30 mL of water was added. The resulting precipitate was collected by suction filtration and washed with water. Chromatography on silica gel yielded the desired product as a dark brown-red solid (0.123 g, 66% yield).  Data for 163.15  1H NMR (300 MHz, CDCl3) δ 7.40-7.38 (m, 2H, Ar), 7.32-7.29 (m, 2H, Ar), 6.90 (s, 2H, Ar), 6.23 (s, 2H, Ar), 3.90 (s, 6H, OCH3), 2.23 (s, 6H, CH3) ppm.  Synthesis of 2,3,6,7,14,15-hexabromotriptycene (164).  A flask containing triptycene (2.000 g, 7.86 mmol) and a spatula tip of iron(III) bromide under nitrogen, with a sodium hydroxide scrub, was cooled in an icebath. Bromine (10 mL) was added in ca. 2 mL aliquots, resulting in a vigorous reaction and the evolution of large amounts of hydrogen bromide gas. The reaction was allowed to warm slowly to room temperature and stirred overnight. Excess 108 bromine was removed in vacuo and the solid residue was dissolved in dichloromethane. The solution was washed with water, with a saturated solution of sodium bicarbonate, and with a solution of sodium thiosulfate. After drying the organic phase over anhydrous magnesium sulfate and filtering, the solvent was removed by rotary evaporation. The solid residue was recrystallized from toluene to yield the desired product as a white crystalline solid (4.127 g, 72% yield).  Data for 164.18  1H NMR (300 MHz, CDCl3) δ 7.60 (s, 6H, Ar), 5.21 (s, 2H, bridgehead) ppm.  Synthesis of 2,3,6,7,14,15-hexamethoxytriptycene (165).  A mixture of 164 (4.920 g, 6.76 mmol), copper(I) bromide (0.602 g, 4.20 mmol), 25 weight% sodium methoxide in methanol (70 mL, 1.22 mol),  ethyl acetate (3 mL), and toluene (80 mL) was refluxed under nitrogen for 16 h. The solution was cooled and quenched with the addition of water. After extracting the aqueous layer with dichloromethane, the combined organic layers were dried over anhydrous magnesium sulfate and filtered. The solvent was removed by rotary evaporation to give the desired product as an off-white solid (2.720 g, 93% yield).  Data for 165.  1H NMR (400 MHz, CDCl3) δ 7.01 (s, 6H, Ar), 5.19 (s, 2H, bridgehead), 3.84 (s, 18H, OCH3) ppm.  13C NMR (100.6 MHz, CDCl3) δ 145.7, 138.9, 108.4, 56.2, 53.1 ppm. HR-MS (EI, 70 eV) Calcd. for C26H26O6: 434.17294; Found: 434.17388.  IR ν = 2949, 2830, 1615, 1586, 1484, 1462, 1403, 1281, 1221, 1183, 1144, 1086, 1023, 983, 870, 743, 608, 589 cm-1.  Mp. = 262-265 °C. 109  Synthesis of 9,10-dimethyltriptycene (167).  To a solution of anthranilic acid (8.231 g, 60.02 mmol) and trichloroacetic acid (0.11 g, 0.67 mmol) in THF (60 mL) cooled in an icebath was added isoamyl nitrite (13 mL, 97 mmol) in ca. 1 mL aliquots over 10 mins. The solution was stirred at room temperature for 1.5 h and cooled in an icebath. The precipitate was collected by suction filtration and washed with cold THF and 1,2-dichloroethane, but was left slightly moist to give the diazonium 160 as a tan solid. CAUTION!! Compound 160 is shock- and heat-sensitive when dry and is known to decompose explosively!! Compound 160 was added without delay to a solution of 166 (9.065 g, 43.95 mmol) in dry 1,2-dichloroethane (200 mL) and the mixture was heated under nitrogen, resulting in the evolution of gas and the solution becoming brown. After the solution was refluxed under nitrogen overnight and cooled to room temperature, the solvent was removed by rotary evaporation. The solid residue was suspended in methanol, collected by suction filtration and washed with methanol to remove the majority of the brown colour. Recrystallization from toluene yielded the desired compound as an off-white crystalline solid (10.896 g, 88% yield).  Data for 167.19  1H NMR (300 MHz, CDCl3) δ 7.38-7.35 (m, 6H, Ar), 7.05-7.02 (m, 6H, Ar), 2.43 (s, 6H, CH3) ppm.  Synthesis of 2,3,6,7,14,15-hexabromo-9,10-dimethyltriptycene (168).  A flask containing 167 (2.002 g, 7.09 mmol) and a spatula tip of iron(III) bromide under nitrogen, with a sodium hydroxide scrub, was cooled in an icebath. Bromine (20 mL) was added in ca. 2 mL aliquots, 110 resulting in a vigorous reaction and the evolution of large amounts of hydrogen bromide gas. The reaction was allowed to warm slowly to room temperature and stirred overnight. Excess bromine was removed in vacuo and the solid residue was dissolved in dichloromethane. The solution was washed with water, with a saturated solution of sodium bicarbonate, and with a solution of sodium thiosulfate. After drying the organic phase over anhydrous magnesium sulfate and filtering, the solvent was removed by rotary evaporation to yield the desired product as an off-white solid (4.639 g, 90% yield).  Data for 168.  1H NMR (300 MHz, CDCl3) δ 7.53 (s, 6H, Ar), 2.29 (s, 6H, CH3) ppm.  13C NMR (100.6 MHz, CDCl3) δ 147.1, 126.4, 121.7, 47.6, 13.0 ppm.  HR-MS (EI, 70 eV) Calcd. for C22H1279Br381Br3: 755.59778; Found: 755.59727.  IR ν = 2973, 1548, 1428, 1387, 1352, 1279, 1110, 1048, 928, 891, 825, 529 cm-1.  Mp. > 300 °C.  Synthesis of 2,3,6,7,14,15-hexamethoxy-9,10-dimethyltriptycene (169).  A mixture of 168 (5.040 g, 6.66 mmol), copper(I) bromide (1.043 g, 7.27 mmol), 25 weight% sodium methoxide in methanol (100 mL, 1.75 mol),  ethyl acetate (10 mL), and toluene (100 mL) was refluxed under nitrogen for 3 d. The solution was cooled and quenched with the addition of water. After extracting the aqueous layer with dichloromethane, the combined organic layers were dried over anhydrous magnesium sulfate and filtered. The solvent was removed by rotary evaporation to give the desired product as a white solid (1.537 g, 50% yield).  Data for 169.12  1H NMR (300 MHz, CDCl3) δ 6.93 (s, 6H, Ar), 3.85 (s, 18H, OCH3), 2.38 (s, 6H, CH3) ppm. 111  Synthesis of 2,3,6,7-tetramethoxy-9,10-dimethyltriptycene o-quinone (171).  To 169 (0.168 g, 0.36 mmol) in acetonitrile (40 mL) was added a solution of CAN (0.498 g, 0.91 mmol) in water (3 mL) dropwise. After stirring for 2 h, the solvent was removed by rotary evaporation to give a dark coloured solid residue that was suspended in water, collected by suction filtration and washed with water. Column chromatography on silica gel with 2% ethyl acetate in dichloromethane and 5% ethyl acetate in dichloromethane gave the desired product as a dark red solid (0.068 g, 43% yield).  Data for 171.15  1H NMR (400 MHz, CDCl3) δ 6.90 (s, 4H, Ar), 6.20 (s, 2H, Ar), 3.90 (s, 12H, OCH3), 2.22 (s, 6H, CH3) ppm.  13C NMR (100.6 MHz, CDCl3) δ 180.4, 156.3, 148.9, 134.0, 117.7, 105.7, 56.3, 46.2, 13.9 ppm.  Synthesis of 2,3-dimethoxy-9,10-dimethyltriptycene bis-o-quinone (172).  To 169 (0.214 g, 0.46 mmol) in acetonitrile (50 mL) was added a solution of CAN (1.152 g, 2.10 mmol) in water (5 mL) dropwise. After stirring for 3 h, the solvent was removed by rotary evaporation to give a dark coloured solid residue that was suspended in water, collected by suction filtration and washed with water. Column chromatography on silica gel with 5% ethyl acetate in dichloromethane gave the desired product as a dark red solid (0.059 g, 32% yield).  Data for 172.15  1H NMR (300 MHz, CDCl3) δ 6.83 (s, 2H, Ar), 6.32 (s, 4H, Ar), 3.93 (s, 6H, OCH3), 2.04 (s, 6H, CH3) ppm.  112 Synthesis of 2,3,6,7-tetrahydroxy-9,10-dimethyltriptycene o-quinone (174).  To a solution of diphenyl diselenide (0.017 g, 0.04 mmol) and a spatula tip of tetrabutylammonium bromide in dichloromethane was added 30% hydrogen peroxide (1 mL, 8.81 mmol) and stirred vigorously for 1 h. Compound 173 (0.050 g, 0.13 mmol) was added and stirred vigorously for 1.5 h. The dark coloured precipate was collected by suction filtration, washed with dichloromethane and water, then dried to give the desired product as an almost black solid (0.036 g , 72% yield).  Data for 174.  1H NMR (400 MHz, acetone-d6) δ 6.90 (s, 4H, Ar), 6.09 (s, 2H, Ar), 2.09 (s, 6H, CH3) ppm; OH resonance not observed due to exchange with trace water present in the solvent.  13C NMR (100.6 MHz, acetone-d6) δ 181.3, 157.9, 145.4, 134.8, 118.0, 110.3, 46.5, 14.2 ppm. HR-MS (ESI, MeOH) Calcd. for C22H16O6Na ([M+Na]+): 399.0845; Found: 399.0837. IR ν (KBr) = 3492, 3223, 2979, 1634, 1614, 1578, 1481, 1448, 1383, 1361, 1339, 1288, 1206, 1180, 1140, 980, 877, 838, 759, 617, 596 cm-1.  Mp. >300 °C.  2.5.3 X-ray crystallographic analysis  Crystals of 162 suitable for X-ray diffraction were grown from a solution of 162 in chloroform, and a suitable crystal was mounted on a glass fibre with oil. All measurements were made on a Bruker X8 diffractometer with graphite monochromated Mo-Kα radiation (λ = 0.71069 Å). The data were collected at a temperature of 173±1 K in a series of φ and ω scans in 0.50º oscillations with 10 s exposures, to a maximum 2θ value of 60.74º. Of the 7017 reflections that were collected, 792 were unique (Rint = 0.0182); equivalent reflections 113 were merged. Data were collected and integrated using the Bruker SAINT software package.20 Data were corrected for absorption effects using a multi-scan technique (SADABS),21 with max and min transmission coefficients of 0.980 and 0.884, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods22 and refined using the SHELXL software.23 All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were included in calculated positions but not refined. The final cycle of full-matrix least-squares refinement on F2 was based on 792 reflections and 44 variable parameters, and converged (largest parameter shift was 0.053 times its esd).24 The crystallographic data is tabulated in Appendix.  114 2.6 References  1. (a) Shalaev, V. K.; Skvarchenko, V. R. Vestnik Moskovskogo Universiteta, Seriya 2: Khimiya 1974, 15, 726-730. (b) Shalaev, V. K.; Getmanova, E. V.; Skvarchenko, V. R. Zh. Org. Khim. 1976, 12, 191-197. 2. (a) Klanderman, B. H.; Perkins, W. C. J. Org. Chem. 1969, 34, 630-633.  (b) Rees, J. H.  J. Chem. Soc., Perkin Trans. 2 1975, 945-947. 3. Hashimoto, M. Japan Patent 359599, 2004. 4. Hart, H.; Bashir-Hashemi, A.; Luo, J.; Meador, M. A. Tetrahedron 1986, 42, 1641- 1654. 5. Minisci, F.; Citterio, A.; Vismara, E.; Fontana, F.; De Bernardinis, S. J. Org. Chem. 1989, 54, 728-731. 6. Macdonald, A. L.; Trotter, J. J. Chem. Soc, Perkin Trans. 2 1973, 476-480. 7. Gong, K.; Zhu, X.; Zhao, R.; Xiong, S.; Mao, L.; Chen, C. Anal. Chem. 2005, 77, 8158-8165. 8. Miao, Q.; Nguyen, T.-Q.; Someya, T.; Blanchet, G. B.; Nuckolls, C. J. Am. Chem. Soc. 2003, 125, 10284-10287. 9. Chung, Y.; Duerr, B. F.; McKelvey, T. A.; Nanjappan, P.; Czarnik, A. W. J. Org. Chem. 1989, 54, 1018-1032. 10. Logullo, F. M.; Seitz, A. H.; Friedman, L. Org. Synth. 1968, 48, 12. 11. Zong, Q.-S.; Chen, C.-F. Org. Lett., 2006, 8, 211-214. 12. Zhu, X.-Z.; Chen, C.-F. J. Am. Chem. Soc. 2005, 127, 13158-13159. 13. Duerr, B. F.; Chung, Y. S.; Czarnik, A. W. J. Org. Chem. 1988, 53, 2120-2122. 14. Pratt, D. V.; Ruan, F.; Hopkins, P. B. J. Org. Chem. 1987, 52, 5053-5055.  115  15. Zhao, J.-M.; Lu, H.-Y.; Cao, J.; Jiang, Y.; Chen, C.-F. Tetrahedron Lett. 2009, 50, 219-222. 16. This carbon appears to have a very long T1 relaxation time, and was not observed in a one dimensional spectrum even after an extended duration with a long delay time between pulses. 17. Peng, X.-X.; Lu, H.-Y.; Han, T.; Chen, C.-F. Org. Lett. 2007, 9, 895-898. 18. Hilton, C. L.; Jamison, C. R.; Zane, H. K.; King, B. T. J. Org. Chem. 2009, 74, 405- 407. 19. Klanderman, B.H.; Criswell, T. R. J. Org, Chem. 1969, 34, 3426-3430. 20. SAINT. Version 6.02. Bruker AXS Inc., Madison, Wisconsin, USA. (1999). 21. SADABS. Bruker Nonius area detector scaling and absorption correction - V2.05, Bruker AXS Inc., Madison, Wisconsin, USA. 22. SIR92: A. Altomare, M. Cascarano, C. Giacovazzo, A. Guagliardi, J. Appl. Cryst. 1994, 26, 343-350. 23. Sheldrick, G. M. Acta Cryst. 2008, A64, 112-122. 24. Least Squares function minimized: Σw(Fo2-Fc2)2 116 CHAPTER 3 TRIPTYCENE-BASED PYRAZINES †  3.1 Introduction  Rigid shape-persistent macrocycles such as porphyrins, phthalocyanines, and cyclic phenyleneethynylenes have emerged as important substances for the study of aggregation and liquid crystallinity.1 Over the past three decades, many strategies have been developed to synthesize large shape-persistent macrocycles, and most involve the incorporation of conjugated components. This typically results in a planar framework where the orbitals involved in conjugation are directed perpendicularly above and below the plane of the macrocycle. Another approach to shape-persistent macrocycles involves belt-shaped molecules such as cyclodextrins and cucurbiturils. 2  Belt-shaped molecules can also be designed to incorporate extended conjugation, as seen in the proposed [n]cyclacene and cyclo[n]phenacene classes of molecules; the conjugated orbitals in these molecules are radially directed.3  † A version of this chapter has been accepted for publication. Chong, J.H. and MacLachlan, M.J. (2007) Synthesis and Structural Investigation of New Triptycene-Based Ligands: En Route to Shape-Persistent Dendrimers and Macrocycles with Large Free Volume. J. Org. Chem. 72:8683-8690. 117   The organization of shape-persistent macrocycles may create molecule-based nanotubes with advantages over other types of nanotubes. For example, although carbon nanotubes possess interesting physical and electronic properties, they are limited by costly and nonintuitive synthetic methods and are difficult to separate.4 These difficulties have hindered the commercial development of nanotubes for wide-ranging applications. The organization of shape-persistent macrocycles into one-dimensional tubes offers the possibility of creating uniform, monodisperse nanotubes with homogeneous properties. This approach has been illustrated with the hydrogen-bonded assemblies of cyclic D-, L-peptides, which have found use as transmembrane channel mimics. 5  With this molecule-based approach to nanotubes, the size of the tube may be controlled, opening new possibilities for host-guest applications such as selective adsorption, catalysis, and nanowire templation. Furthermore, controlled macrocycle aggregation and de-aggregation would be useful in controlling the adsorption and release of guests and would allow for their eventual removal when used in template-directed synthesis.  118 A long-term goal for the work carried out in this thesis is developing shape-persistent ligands such as the giant belt-like macrocycle 182 illustrated in Figure 3.1 for assembly into tubular structures with a large amount of void space. Pyrazine groups on each side of the hexagon could coordinate to metals to link the molecules into a tubular structure or a highly porous three-dimensional framework.6 Central to this design of these ligands is the use of triptycene as a thermally robust component. Triptycene is an ideal building block for macrocycle 182 because the constrained 120° angle between the phenyl rings provides the required geometry to form a hexagon. Extension of triptycene’s phenyl rings would then provide an electronic environment where the orbitals involved in conjugation have a similar direction to other conjugated belt-like molecules.   N N N N N N N N N N N N 182 Figure 3.1.  Target belt-like giant macrocycle 182.  AM1 calculations of 182 show that it should have an inner diameter of 17 Å. While this is likely too large for use in rotaxane chemistry, its size is ideal for forming large shape- persistent nanotubes when stacked on top of each other. These nanotubes would possess hydrophobic interiors that should selectively adsorb nonpolar guests. Furthermore, the π- stacking interactions from the numerous aromatic rings in 182 would be useful for selectively 119 binding a large number of aromatic guests within the pores. Calculations suggest the interior of macrocycle 182 may be able to bind a single molecule of C60 as the intermolecular distances are around 3.7 Å, allowing for π-π interactions; this behaviour has been seen for similar geometrical motifs. 7  Their assembly into nanotubes could be facilitated by coordination of CuI to the apical nitrogen atoms on the top and bottom edges of the macrocycle,8 and incorporation of CuI is expected to maintain the hydrophobicity of the macrocycle, ideal for nonpolar guests. Moreover, metal coordination is expected to assist in holding the nanotubes together and should increase their rigidity and make them more robust.  The simplest method to synthesize the pyrazine moieties in macrocycle 182 and related compounds is through Schiff-base condensation of an o-phenylenediamine with an appropriate dialdehyde or diketone to form quinoxaline- or phenazine-based compounds, respectively. A series of triptycene-based o-phenylenediamines and o-benzoquinones has successfully been synthesized in the previous chapter of this thesis, and they can now be combined to produce the desired compounds. As part of the long-term goal of building a shape-persistent macrocycle for nanotubes, the synthesis and characterization of several quinoxaline- and phenazine-type model compounds that represent portions of the macrocycle will be discussed herein.    120 3.2 Synthesis  The quinoxaline-based triptycenes 131 and 132 were synthesized by Schiff-base condensation with the anhydrous glyoxal equivalent, 2,3-dihydroxy-1,4-dioxane (183),9 since a high concentration of water hinders imine formation (Scheme 3.1).  N N 131 N N N N N N 132 NH2 NH2 136 NH2 NH2 H2N H2N H2N NH2 138 O O OH OH 183 THF O O OH OH 183 THF 67% 29%  Scheme 3.1.  Synthesis of triptycenyl quinoxalines 131 and 132.  Ligand 131 is a model compound that represents a vertex and part of a side of the target macrocycle 182 (Figure 3.2). It was expected that these reactions would be essentially quantitative, but the yields were lowered by the formation of unidentified byproducts. In particular, the reaction to form 132 generated a large amount of a poorly soluble material that is likely to be oligomeric byproducts. The increased number of amino groups on 138 increases the possibility for forming a cross-linked polymer that would be difficult to degrade once it precipitates out of solution, but it was expected that such a polymer would be 121 converted to the thermodynamically stable aromatic quinoxaline over time. Fortunately, it was possible to separate the desired compounds 131 and 132 by column chromatography using polar solvent mixtures.   Figure 3.2.  Representation of compounds 131-135 as model components of macrocycle 182.  The phenazine-type ligands 133-135 were synthesized from quinone 139 (Scheme 3.2). Ligand 133 is a model compound comprising a vertex and a complete side of macrocycle 182, and 134 represents a side and two vertices of 182 (Figure 3.2). THF or THF/ethanol solvent mixtures were initially used as it was believed to be necessary for promoting solubility, but this resulted in low product yields. Because ketones react less rapidly than aldehydes, the reaction time was increased but this did not produce a corresponding yield increase. However, switching to ethanol resulted in reaction mixtures that were easy to purify and gave reasonable yields of 61% and 68% for 133 and 134, respectively.  122 N N 134 N N 133 N N N N N N 135 O O 139 EtOH NH2 NH2 NH2 NH2 136 O O 139 EtOH NH2 NH2 H2N H2N H2N NH2 138 O O 139 EtOH N H H N cat. 61% 68% 35%  Scheme 3.2.  Synthesis of triptycenyl phenazines 133-135.  Initial attempts to form 135 were particularly problematic as only trace quantities of the desired product were detected. Interestingly, the use of ethanol did not produce a significant improvement, as it did with 133 and 134. To deal with the possibility of the 123 intermediates being insoluble, THF and THF/ethanol solvent mixtures were used, but this produced no significant improvement and resulted in the formation of polymer. Such a polymeric byproduct may be more problematic when a ketone such as 139 is used instead of an aldehyde because the resulting ketimines are less reactive, making the system less reversible and more difficult to reach the desired thermodynamic product. Fortunately, using a catalytic amount of piperidine in combination with ethanol improved the yield of 135 sufficiently to 35%, allowing it to be isolated and purified. The base serves as a catalyst for the reaction, making it easier to reverse the formation of unwanted kinetic byproducts. Purification of 135 was facilitated by column chromatography with an alumina stationary phase. NMR spectroscopy showed the expected signals and also confirmed that there are no impurities present (Figure 3.3).  124  Figure 3.3.  1H NMR spectrum (300 MHz, CDCl3) of 135.  (* = CHCl3,  † = water)  MALDI-TOF mass spectrometry for 135 showed the expected [M+H]+ ion, without any observable oligomeric or polymeric impurities (Figure 3.4).  125  Figure 3.4.  MALDI-TOF mass spectrum of 135 (dithranol matrix).  3.3 Characterization  3.3.1 NMR studies  The chemical shift of the triptycenyl bridgehead protons is a useful diagnostic feature for all triptycene compounds as it is sensitive to changes on the phenyl rings. For the compounds in this chapter, the chemical shifts are dependent on the number of substituted 126 phenyl rings adjacent to the bridgehead (Table 3.1). Bridgeheads with three adjacent quinoxaline or phenazine moieties have protons that resonate downfield by ca. 0.4 ppm compared to those that only have a single adjacent quinoxaline or phenazine. This can be seen in the chemical shifts for 135; the protons on its inner bridgehead resonate 0.46 ppm downfield of those on its outer bridgeheads (Figure 3.3). Although sensitive to the number of substitutions, the chemical shift is not significantly affected by the presence of a quinoxaline versus a phenazine moiety.  Table 3.1.  1H NMR resonances of the bridgehead protons for 131-135. Compound chemical shift (ppm)a 131 5.64 132 6.13 133 5.66 134 5.61 135 5.59b, 6.05c a  Calibrated internally to residual CHCl3. b  Resonance of outer bridgehead protons. c  Resonance of inner bridgehead protons.  3.3.2 Thermogravimetric analysis  Ligands 131-133 were stable to high temperatures of 341, 442, and 378 °C, respectively, while 134 and 135 showed mass losses beginning at 169 and 163 °C, respectively (Figure 3.5). It appears that thermal stability of these compounds decreases as 127 the number of triptycenyl wings increases. Interestingly, compounds 131 and 133, with only a single set of wings, essentially have a single decomposition where the entire mass is lost in one step. As the number of triptycenyl wings increases, so does the number of decomposition steps, with 135 appearing to have three stages of mass loss.   Figure 3.5.  Thermogravimetric analysis of 131-135 (heating rate of 10 °C min-1).  3.3.3 Crystallographic studies  To study how changes in the structure of the compounds affect their packing in the solid state, single-crystal X-ray diffraction experiments of 131-134 were undertaken. In the 128 solid state, 131 packs into a layered structure, and within each layer the molecules show interdigitated cofacial assembly (Figure 3.6). The pyrazine ring lies over top of the phenyl ring on the other molecule with a separation of 3.7 Å; this allows for weak π-stacking between pairs of molecules within each layer. This appears to be a relatively efficient packing arrangement as there are no guest solvent molecules in the lattice and the structure has a calculated density of 1.35 g cm-3.   Figure 3.6.  Solid-state structure of 131. Hydrogens have been omitted for clarity.  (a) View along the a-axis showing a layered structure. (b) View along the b-axis showing interdigitated cofacial assembly.  (c) View of π-stacked dimers.  (d) ORTEP of single molecule. Ellipsoids are shown at the 50% probability level. Carbon, black; nitrogen, blue.  129 Crystals of trisquinoxaline 132 were obtained from two different solvents, acetonitrile and THF. The structure of 132 crystallized from acetonitrile contains 12 guest acetonitrile molecules per unit cell (1.5 molecules of acetonitrile per molecule of 132 as one acetonitrile lies on a mirror plane) (Figure 3.7). This structure contains two layers orientated orthogonally to each other. A similar π-stacking arrangement, with the phenyl ring being over top of the pyrazine ring separated by 3.6 Å, can be seen between pairs of adjacent molecules within the same layer. This packing arrangement is sufficiently poor that there is space to accommodate acetonitrile in the lattice. 130  Figure 3.7.  Solid-state structure of 132 crystallized from acetonitrile. Hydrogens have been omitted for clarity.  (a) View showing orthogonal layers. Guest solvent molecules have been omitted for clarity.  (b) View down b-axis showing π-stacking (acetonitrile molecules shown in red).  (c) ORTEP of single molecule. Ellipsoids are shown at the 50% probability level. Carbon, black; nitrogen, blue.  Interestingly, the solid-state structure of 132 crystallized from THF is completely different (Figure 3.8). In this structure, there is no guest solvent in the lattice. This solvent- free structure has two layers that are twisted with respect to each other by roughly 30°, allowing for a more efficient filling of space. However, this geometry does not allow for the π-stacking interactions that may have been required to stabilize the more loosely packed form obtained from acetonitrile. The structure of 132 crystallized from acetonitrile has a calculated 131 density of 1.20 g cm-3 (1.38 g cm-3 with the presence of solvent guests), whereas crystallizing from THF gives a higher density of 1.42 g cm-3 (no solvent guests).   Figure 3.8.  Solid-state structure of 132 crystallized from THF. Hydrogens have been omitted for clarity.  (a) View showing the presence of layers with two different orientations. (b) ORTEP of single molecule. Ellipsoids are shown at the 50% probability level. Carbon, black; nitrogen, blue.  The smallest triptycenyl phenazine (133) packs into a layered structure with interdigitated cofacial assembly within each layer, which is similar to the structure for 131 (Figure 3.9). Again, there is weak π-stacking between pairs of molecules in the same layer with a separation of 3.8 Å. Ligand 133 differs from 131 as the pyrazine rings in 133 stack directly on top of each other and not over top of the adjacent phenyl rings. This form of packing leads to minimal free space in the lattice (calculated density of 1.34 g cm-3), with no guest solvent, demonstrating that lengthening one of the wings has little effect on solid-state packing efficiency.  132  Figure 3.9.  Solid-state structure of 133. Hydrogens have been omitted for clarity.  (a) View along the a-axis showing layered structure.  (b) View along b-axis showing interdigitated cofacial assembly with π-stacking interactions.  (c) ORTEP of single molecule. Ellipsoids are shown at the 50% probability level. Carbon, black; nitrogen, blue.  However, adding another triptycenyl moiety resulting in a molecule with two sets of triptycenyl wings, as in 134, produces a significant decrease in the solid-state packing efficiency. It is clear that the structure of this compound would restrict close packing. The molecules of 134 are arranged into two layers that are twisted with respect to each other, presumably to fill space more efficiently (Figure 3.10). However, the presence of guest solvent molecules shows that this arrangement is not as efficient as the packing of 131 and 133, with a calculated density of 1.26 g cm-3 (1.31 g cm-3 with the presence of solvent guests). 133 There is also no observed π-stacking, as the extra triptycenyl moiety prevents the molecules from approaching each other closely enough with the correct orientation.   Figure 3.10.  Solid-state structure of 134. Hydrogens have been omitted for clarity.  (a) View along the a-axis (acetonitrile molecules shown in red).  (b) View along the b-axis. Guest solvent molecules have been omitted for clarity.  (c) ORTEP of single molecule. Ellipsoids are shown at the 50% probability level. Carbon, black; nitrogen, blue.  Unfortunately, attempts to crystallize 135 have so far been unsuccessful. Compound 135 can also be considered as the zeroth generation of a triptycenyl-based dendrimer (Figure 3.11); subsequent generations could be synthesized divergently by alternating condensations of aminotriptycenes with triptycenyl quinones. Such dendrimers would also be expected to 134 exhibit poor packing in the solid state, and if the expected void spaces are guest-free, these dendrimers may be useful as low-κ dielectric materials for electronic applications. With a high accessible surface area that is constructed with aromatic rings, the dendrimers may also be promising hydrogen storage materials.   Figure 3.11.  Zeroth (135) and first generations of the proposed triptycenyl dendrimer.  3.4 Conclusions  Triptycene-based o-phenylenediamine and o-benzoquinone precursors were used to build a series of compounds containing pyrazine moieties for use in forming coordination frameworks and as model compounds toward target shape-persistent dendrimers and macrocycles. The packing arrangements of the quinoxaline-based 131 and 132, and of the phenazine-based 133 and 134 in the solid state were studied by X-ray crystallography, showing that these compounds favour packing in layered structures with intermolecular π- stacking. Increasing the length of the wings still allowed for effective packing, but increasing the number of pyrazine groups or adding more triptycenyl moieties disrupted intermolecular interactions that lead to efficient packing. Due to their rigid nature and having pyrazine 135 moieties, 131-134 are promising candidates as ligands for the development of robust coordination frameworks with large free volume. The rigid, shape-persistent first generation dendrimer 135 based on this chemistry was also successfully synthesized.  3.5 Experimental  3.5.1 General  Materials.  Compounds 136, 138, and 139 were prepared as described in Chapter 2 of this thesis. Compound 183 was prepared according to a literature procedure.9 Other reagents were obtained from standard suppliers. All reactions were performed under a nitrogen atmosphere. Solvents were degassed by sparging them with nitrogen before use.  Equipment.  1H and 13C NMR spectra were recorded on a Bruker AV-300 spectrometer. 13C NMR spectra were recorded using a proton decoupled pulse sequence. 1H NMR spectra were calibrated to the residual protonated solvent at δ 7.26 ppm and 13C NMR spectra were calibrated to the deuterated solvent at δ 77.00 ppm in CDCl3. IR spectra were obtained as KBr discs with a Bomems MB-series spectrometer. EI spectra were obtained using a double focusing mass spectrometer (Kratos MS-50) coupled with a MASPEC data system with EI operating conditions of: source temperatures 120-250°C and ionization energy 70 eV. Melting points were obtained on a Fisher-John’s melting point apparatus. MALDI mass spectra were obtained on a spectrometer coupled to a TOF detector, and samples were 136 prepared using a dithranol matrix. TGA data was obtained using a Perker Elmer TGA6 instrument.  3.5.2 Procedures  Synthesis of triptycenyl quinoxaline 131.  To a solution of 136 (0.814 g, 2.86 mmol) in THF (150 mL) was added 183 (0.391 g, 3.26 mmol), and stirred overnight to give a yellow solution. The solvent was removed by rotary evaporation, and the red-orange residue was chromatographed on silica gel with 1:9 ethyl acetate:dichloromethane to give the product as an off-white solid (0.587 g, 67% yield).  Data for 131.  1H NMR (300 MHz, CDCl3) δ 8.70 (s, 2H, Ar), 7.99 (s, 2H, Ar), 7.47-7.44 (m, 4H, Ar), 7.07-7.04 (m, 4H, Ar), 5.64 (s, 2H, bridgehead) ppm.  13C NMR (75.4 MHz, CDCl3) δ 146.7, 144.2, 143.7, 142.0, 126.0, 124.1, 122.9, 53.6 ppm.  MS (EI, 70 eV) m/z 305 (M+). IR ν (KBr) = 3423, 3056, 2959, 1470, 1459, 1433, 1364, 1174, 1157, 1069, 1029, 940, 899, 769, 742, 629, 577, 496 cm-1.  Mp. > 300 °C.  Anal. Calcd for C22H14N2: C, 86.25; H, 4.61; N, 9.14. Found: C, 85.90; H, 4.78; N, 9.41.  Synthesis of triptycenyl quinoxaline 132.  To a solution of 138 (0.319 g, 0.93 mmol) in THF (120 mL) was added 183 (0.334 g, 2.78 mmol), and stirred overnight to give an orange solution. The solvent was removed by rotary evaporation, and the brown residue was chromatographed on silica gel with 1:9 methanol:dichloromethane to give the product as an off-white solid (0.112 g, 29% yield). 137  Data for 132.  1H NMR (300 MHz, CDCl3) δ 8.76 (s, 6H, Ar), 8.21 (s, 6H, Ar), 6.13 (s, 2H, Ar) ppm.  13C NMR (75.4 MHz, CDCl3) δ 144.9, 143.7, 142.2, 124.4, 52.8 ppm.  MS (EI, 70 eV) m/z 410 (M+).  IR ν (KBr) = 3433, 3047, 1474, 1430, 1366, 1176, 1078, 1025, 934, 901, 747, 577 cm-1.  Mp. > 300 °C.  Anal. Calcd for C26H14N6: C, 76.09; H, 3.44; N, 20.48. Found: C, 75.87; H, 3.57; N, 20.36.  Synthesis of triptycenyl phenazine 133.  To a flask containing o-phenylenediamine (0.050 g, 0.46 mmol) and 139 (0.150 g, 0.53 mmol) was added ethanol (30 mL). The solution was refluxed for 1.5 h, and the solvent was removed by rotary evaporation. Column chromatography of the residue on silica gel with dichloromethane yielded the desired product as a pale yellow solid (0.101 g, 61% yield).  Data for 133.  1H NMR (300 MHz, CDCl3) δ 8.17-8.14 (m, 2H, Ar), 8.07 (s, 2H, Ar), 7.75- 7.72 (m, 2H, Ar), 7.50-7.48 (m, 4H, Ar), 7.10-7.08 (m, 4H, Ar), 5.66 (s, 2H, bridgehead) ppm.  13C NMR (75.4 MHz, CDCl3) δ 146.6, 143.2, 143.0, 142.9, 129.8, 129.4, 126.2, 124.1, 122.4, 53.5 ppm.  MS (EI, 70 eV) m/z 356 (M+).  IR ν (KBr) = 3430, 3072, 3039, 2954, 1526, 1461, 1429, 1357, 1319, 1203, 1180, 1159, 1130, 1025, 1002, 886, 859, 801 cm-1.  Mp. > 300 °C.  Anal. Calcd for C26H16N2: C, 87.62; N, 7.86; H, 4.52. Found: C, 87.44; N, 7.81; H, 4.61.  Synthesis of triptycenyl phenazine 134. To a flask containing 136 (0.100 g, 0.35 mmol) and 139 (0.110 g, 0.39 mmol) was added ethanol (50 mL). The solution was refluxed for 1.5 h, 138 and the solvent was removed by rotary evaporation. Column chromatography of the residue on silica gel with dichloromethane yielded the desired product as a pale yellow solid (0.128 g, 68% yield).  Data for 134.  1H NMR (300 MHz, CDCl3) δ 8.00 (s, 4H, Ar), 7.47-7.44 (m, 8H, Ar), 7.07- 7.05 (m, 8H, Ar), 5.61 (s, 4H, bridgehead) ppm.  13C NMR (75.4 MHz, CDCl3) δ 145.8, 143.4, 142.3, 126.1, 124.1, 122.4, 53.5 ppm.  MS (EI, 70 eV) m/z 532 (M+).  IR ν (KBr) = 3071, 3037, 2955, 1530, 1461, 1425, 1347, 1315, 1245, 1210, 1201, 1166, 1157, 1071, 1026, 878, 799, 763, 754, 739, 724 cm-1. Mp. > 300 °C.  Anal. Calcd for C40H24N2: C, 90.20; N, 5.26; H, 4.54. Found: C, 89.87; N, 5.66; H, 4.73.  Synthesis of triptycenyl phenazine 135. To a flask containing 138 (0.025 g, 0.07 mmol) and 139 (0.100 g, 0.35 mmol) was added a degassed mixture of ethanol (40 mL) and 6 drops of piperidine. The solution was refluxed overnight, and the solvent was removed by rotary evaporation. Chromatography of the residue on an alumina column with 1:9 ethyl acetate:dichloromethane gave the desired product as a pale yellow solid (0.028 g, 35% yield).  Data for 135.  1H NMR (300 MHz, CDCl3) δ 8.23 (s, 6H, Ar), 7.99 (s, 6H, Ar), 7.45-7.41 (m, 12H, Ar), 7.06-7.03 (m, 12H, Ar), 6.05 (s, 2H, bridgehead), 5.59 (s, 6H, bridgehead) ppm. 13C NMR (75.4 MHz, CDCl3) δ 146.4, 143.2, 142.75, 142.69, 142.4, 126.2, 124.1, 124.0, 122.4, 53.5, 52.9 ppm.  MS (MALDI, dithranol) m/z 1089.7 ([M+H]+).  IR ν (KBr) = 3438, 3072, 3043, 3024, 2961, 1526, 1492, 1459, 1422, 1348, 1271, 1223, 1160, 883, 733 cm-1. 139 Mp. > 300 °C.  Anal. Calcd for C80H44N6•2H2O: C, 85.39; N, 7.47; H, 4.30. Found: C, 85.59; N, 7.52; H, 4.48. 3.5.3 X-ray crystallographic analysis  General.  Suitable crystals of compounds 131-134 were mounted on a glass fibre with oil and data for each compound was collected at 173±1 K using graphite monochromated Mo-Kα radiation (λ = 0.71069 Å). Structure solutions were refined using the SHELXL software.10 Crystallographic data for these compounds are tabulated in Appendix 1.  X-ray diffraction study of 131.  Crystals of 131 suitable for X-ray diffraction were grown by layering acetonitrile on a solution of 131 in chloroform.  All measurements were made on a Rigaku/ADSC diffractometer. Data were collected to a maximum 2θ value of 55.7º in a series of φ and ω scans in 0.50º oscillations with 35 s exposures. Of the 6811 reflections that were collected, 3092 were unique (Rint = 0.032); equivalent reflections were merged. The data was collected and integrated using d*TREK. 11  Data were corrected for absorption effects using a multi-scan technique, with max and min transmission coefficients of 1.000 and 0.8033, respectively.  The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods. 12  All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were included in calculated positions but not refined. The final cycle of full-matrix least-squares refinement on F2 was based on 3092 reflections and 217 variable parameters and converged (largest parameter shift was 0.000 times its esd).13  140 X-ray diffraction study of 132. Crystals of 132 suitable for X-ray diffraction were grown by slow evaporation of a solution of 132 in THF.  All measurements were made on a Bruker X8 diffractometer. Data was collected to a maximum 2θ value of 52.68º in a series of φ and ω scans in 0.50º oscillations with 12 s exposures. Of the 26387 reflections that were collected, 4554 were unique (Rint = 0.0481); equivalent reflections were merged. Data were collected and integrated using the Bruker SAINT software package. 14  Data were corrected for absorption effects using a multi-scan technique (SADABS)15, with max and min transmission coefficients of 0.991 and 0.820, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.16 All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were located by difference mapping and refined isotropically. The final cycle of full-matrix least-squares refinement on F2 was based on 4554 reflections and 345 variable parameters and converged (largest parameter shift was 0.000 times its esd).13  X-ray diffraction study of 132 • 1.5MeCN. Crystals of 132 • 1.5MeCN suitable for X-ray diffraction were grown by layering acetonitrile on a solution of 132 in chloroform.  All measurements were made on a Bruker X8 diffractometer. Data was collected to a maximum 2θ value of 47.64º in a series of φ and ω scans in 0.50º oscillations with 30s exposures. Of the 34031 reflections that were collected, 3420 were unique (Rint = 0.0981); equivalent reflections were merged. Data were collected and integrated using the Bruker SAINT software package.14 Data were corrected for absorption effects using a multi-scan technique (SADABS)15, with max and min transmission coefficients of 0.996 and 0.746, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by 141 direct methods.16 All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were located by difference mapping and refined isotropically. The final cycle of full-matrix least-squares refinement on F2 was based on 3420 reflections and 399 variable parameters and converged (largest parameter shift was 0.000 times its esd).13  X-ray diffraction study of 133.  Crystals of 133 suitable for X-ray diffraction were grown by layering acetonitrile on a solution of 133 in chloroform.  All measurements were made on a Rigaku AFC7 diffractometer. Data were collected to a maximum 2θ value of 50.54º in a series of φ and ω scans in 0.50º oscillations with 16 s exposures. Of the 8208 reflections that were collected, 8208 were unique (Rint = 0.032); equivalent reflections were merged. The data was collected using d*TREK11 and integrated using the Twinsolve module in the Crystalclear software package.17 Data were corrected for absorption effects using a multi- scan technique, with max and min transmission coefficients of 1.000 and 0.9035, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.16 All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were located by difference mapping and were refined isotropically. The final cycle of full- matrix least-squares refinement on F2 was based on 8208 reflections and 318 variable parameters and converged (largest parameter shift was 0.000 times its esd).13  X-ray diffraction study of 134 • MeCN.  Crystals of 134 • MeCN suitable for X-ray diffraction were grown by layering acetonitrile on a solution of 134 in chloroform.  All measurements were made on a Rigaku/ADSC diffractometer. Data was collected to a maximum 2θ value of 45.14º in a series of φ and ω scans in 0.50º oscillations with 16 s 142 exposures. Of the 3764 reflections that were collected, 3764 were unique (Rint = 0.0765); equivalent reflections were merged. The data was collected using d*TREK11 and integrated using the Twinsolve module in the Crystalclear software package.17 Data were corrected for absorption effects using a multi-scan technique, with max and min transmission coefficients of 1.000 and 0.9966, respectively.  The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.16 All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were included in calculated positions but not refined. The final cycle of full-matrix least-squares refinement on F2 was based on 3764 reflections and 407 variable parameters and converged (largest parameter shift was 0.000 times its esd).13  143 3.6 References  1. (a) Balaban, T. S. Acc. Chem. Res. 2005, 38, 612-623.  (b) Elemans, J. A. A. W.; van Hameren, R.; Nolte, R. J. M.; Rowan, A. E. Adv. Mater. 2006, 18, 1251-1266.  (c) Eichhorn, H. J. Porphyrins Phthalocyanines 2000, 4, 88-102.  (d) Hu, J.-S.; Guo, Y.- G.; Liang, H.-P.; Wan, L.-J.; Jiang, L. J. Am. Chem. Soc. 2005, 127, 17090-17095.  (e) Castella, M.; Lopez-Calahorra, F.; Velasco, D.; Finkelmann, H. Chem. Commun. 2002, 2348-2349.  (f) Jasat, A.; Dolphin, D. Chem. Rev. 1997, 97, 2267-2340.  (g) van Nostrum, C. F. Adv. Mater. 1996, 8, 1027-1030.  (h) Zhang, J.; Moore, J. S. J. Am. Chem. Soc. 1992, 114, 9701-9702.  (i) Inabe, T. J. Porphyrins Phthalocyanines 2001, 5, 3-12.  (j) Lahiri, S.; Thompson, J. L.; Moore, J. S. J. Am. Chem. Soc. 2000, 122, 11315-11319.  (k) Höger, S.; Bonrad, K.; Mourran, A.; Beginn, U.; Möller, M. J. Am. Chem. Soc. 2001, 123, 5651-5659.  (l) Rosselli, S.; Ramminger, A.-D.; Wagner, T.; Lieser, G.; Höger, S. Chem. Eur. J. 2003, 9, 3481-3491. 2. (a) Szejtli, J. Pure Appl. Chem. 2004, 76, 1825-1845.  (b) Harada, A. J. Polym. Sci., Part A: Polym. Chem. 2006, 44, 5113-5119.  (c) Harada, A. Acc. Chem. Res. 2001, 34, 456-464.  (d) Kim, K.; Selvapalam, N.; Ko, Y. H.; Park, K. M.; Kim, D.; Kim, J. Chem. Soc. Rev. 2007, 36, 267-279.  (e) Lee, J. W.; Samal, S.; Selvapalam, N.; Kim, H.-J.; Kim, K. Acc. Chem. Res. 2003, 36, 621-630. 3. (a) Tahara, K.; Tobe, Y. Chem. Rev. 2006, 106, 5274-5290.  (b) Ashton, P. R.; Brown, G. R.; Isaacs, N. S.; Giuffrida, D.; Kohnke, F. H.; Mathias, J. P.; Slawin, A. M. Z.; Smith, D. R.; Stoddart, J. F.; Williams, D. J. J. Am. Chem. Soc. 1992, 114, 6330-6353. (c) Cory, R. M.; McPhail, C. L. Tetrahedron Lett. 1996, 37, 1987-1990.  (d) Neudorff,  144  W. D.; Lentz, D.; Anibarro, M.; Schlüter, A. D. Chem. Eur. J. 2003, 9, 2745-2757.  (e) Nakamura, E.; Tahara, K.; Matsuo, Y.; Sawamura, M. J. Am. Chem. Soc. 2003, 125, 2834-2835. 4. (a) Ajayan, P. M. Chem. Rev. 1999, 99, 1787-1800.  (b) Tasis, D.; Tagmatarchis, N.; Bianco, A.; Prato, M. Chem. Rev. 2006, 106, 1105-1136. 5. (a) Ghadiri, M. R.; Granja, J. R.; Milligan, R. A.; McRee, D. E.; Khazanovich, N. Nature 1993, 366, 324-327.  (b) Khazanovich, N.; Granja, J. R.; McRee, D. E.; Milligan, R. A.; Ghadiri, M. R. J. Am. Chem. Soc. 1994, 116, 6011-6012.  (c) Ghadiri, M. R.; Granja, J. R.; Buehler, L. K. Nature 1994, 369, 301-304.  (d) Granja, J. R.; Ghadiri, M. R. J. Am. Chem. Soc. 1994, 116, 10785-10786.  (e) Bong, D. T.; Ghadiri, M. R. Angew. Chem. Int. Ed. 2001, 40, 2163-2166. 6. Campbell, K.; Kuehl, C. J.; Ferguson, M. J.; Stang, P. J.; Tykwinski, R. R. J. Am. Chem. Soc. 2002, 124, 7266-7267. 7. (a) Kawase, T.; Kurata, H. Chem. Rev. 2006, 106, 5250-5273.  (b)Veen, E. M.; Feringa, B. L.; Postma, P. M.; Jonkman, H. T.; Spek, A. L. Chem. Commun. 1999, 1709-1710. 8. (a) Graham, P. M.; Pike, R. D.; Sabat, M.; Bailey, R. D.; Pennington, W. T. Inorg. Chem. 2000, 39, 5121.  (b) Chesnut, D. J.; Plewak, D.; Zubieta, J. J. Chem. Soc., Dalton Trans. 2001, 2567. 9. Venuti, M. C. Synthesis 1982, 1, 61. 10. Sheldrick, G. M. Acta Cryst. 2008, A64, 112-122. 11. d*TREK. Area Detector Software. Version 7.1I. Molecular Structure Corporation.  145  2001. 12. SIR97. Altomare, A.; Burla, M. C.; Cammali, G.; Cascarano, M.; Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna, A. J. Appl. Cryst. 1999, 32, 115-119. 13. Least Squares function minimized:   Σw(Fo2-Fc2)2 14. SAINT. Version 6.02. Bruker AXS Inc., Madison, Wisconsin, USA. 1999. 15. SADABS. Bruker Nonius area detector scaling and absorption correction - V2.05, Bruker AXS Inc., Madison, Wisconsin, USA. 16. SIR92. Altomare, A.; Cascarano, M.; Giacovazzo, C.; Guagliardi, A. J. Appl. Cryst. 1994, 26, 343-350 17. CrystalClear 1.3.5 SP2. Molecular Structure Corporation. 2003. 146 CHAPTER 4 TRIPTYCENYL PYRAZINE METAL-ORGANIC FRAMEWORKS †  4.1 Introduction  Metal-organic coordination frameworks are promising candidates for developing new sorbent, catalytic, or electronic materials.1 Variation of synthetic conditions and precursors enables tuning of the pore sizes, pore geometries, and magnetic/optical properties. Unfortunately, most coordination frameworks are either subject to interpenetration that renders them non-porous, or they are unstable to solvent removal, preventing their use in applications requiring accessible pores. Using secondary building units or molecules that do not pack well together (e.g., 9,9’-spirobifluorenes, rotaxanes) to assemble structures can prevent interpenetration.2  Environmental remediation has been proposed as an application of metal-organic frameworks, but has not been demonstrated. With the goal of developing porous, hydrophobic framework materials, we targeted a new class of ligands based on triptycene, a molecule with a large built-in free volume. Triptycene and its derivatives have been used to  † A version of this chapter has been accepted for publication. Chong, J.H. and MacLachlan, M.J. (2006) Robust Non-Interpenetrating Coordination Frameworks from New Shape- Persistent Building Blocks. Inorg. Chem. 45:1442-1444. 147 inhibit aggregation in conjugated polymers and to align liquid crystals.3 However, their use to develop porous networks has not been adequately explored, apart from the formation of silver(I) coordination polymers and one report of zinc(II) metal-organic frameworks.4  The pyrazine-containing triptycenes 131-135 prepared in the preceeding chapter of this thesis are promising candidates for forming highly porous coordination frameworks. Firstly, their pyrazine moieties provide bidirectional coordination sites that are necessary to form an extended coordination framework. Secondly, triptycene’s rigid nature and its ability to enforce free volume by hindering efficient packing should create pores in the resulting extended coordination networks.  4.2 Preparation and Characterization of Frameworks  Since stability is an important requirement for coordination frameworks to be used in materials applications, it is desirable to maximize the strength of the ligand-metal interactions by pairing the soft quinoxaline and phenazine proligands with soft transition metals. Therefore, a solution of copper(I) iodide in acetonitrile was layered upon chloroform solutions of the quinoxaline-based 131 and 132, affording the red single crystalline solids 184•MeCN and 185•2MeCN, respectively (Scheme 4.1). The structures of these products were determined by single-crystal X-ray diffraction.  148 N N 131 N N N N N N 132 + 2 CuI MeCN/CHCl3 184 • MeCN + 4 CuI MeCN/CHCl3 185 • 2MeCN  Scheme 4.1.  Preparation of coordination frameworks 184 and 185.  In 184•MeCN, the copper atoms are each coordinated to one quinoxaline and to three iodide ligands (Figure 4.1). A (CuI)n polymeric ladder structure extends along the c-axis and there is also a chain of alternating copper atoms and quinoxaline ligands along the a-axis, producing a two-dimensional coordination framework. These motifs have been observed in other quinoxaline-copper systems with similar topologies,5 but in this case the free volume of the shape-persistent ligand 131 generates a channel structure in the lattice. Rectangular channels measuring ca. 12 × 5 Å run parallel to the direction of the copper/iodide chains along the c-axis, and contain four guest acetonitrile molecules per unit cell. If the presence of the guest solvent molecules is ignored, this framework would have a void space of 44%, as calculated by PLATON.6 149  Figure 4.1.  Solid-state structure of 184•MeCN. Hydrogens have been omitted for clarity. (a) View along the a-axis. Solvent molecules have been omitted for clarity.  (b) View along the b-axis showing (CuI)n chains. Solvent molecules have been omitted for clarity.  (c) View along the c-axis showing a solvent-filled channel (acetonitrile molecules shown in brown). (d) ORTEP of asymmetric unit, solvent molecules excluded. Ellipsoids are shown at the 50% probability level. Carbon, black; nitrogen, blue; copper, green; iodine, red.  In 185•2MeCN, the copper atoms also have a tetrahedral coordination environment, being coordinated to both quinoxaline and iodide ligands (Figure 4.2). Only two out of the three quinoxalines on each ligand 132 coordinate to copper; the third ring does not coordinate. Similar to 184•MeCN, 185•2MeCN has chains of alternating copper atoms and quinoxaline ligands in one direction, along the a-axis. However, the (CuI)n chains running 150 perpendicular are not infinite chains, but are present as (CuI)8 oligomers with terminal acetonitrile ligands. This breaking up of the (CuI)n chains causes the material to be a two- dimensional coordination framework instead of the expected three-dimensional framework The topology of 185•2MeCN is not obvious, but it appears to have an undulating layered motif. This layered framework has three types of small channels that run parallel to the a-axis and two of these are occupied by eight non-coordinated guest acetonitrile molecules per unit cell. If the presence of the acetonitrile molecules are ignored the structure would have a void space of 44%, and with coordinated acetonitrile molecules the amount of void space decreases to 39%. 151  Figure 4.2.  Solid-state structure of 185•2MeCN. Hydrogens have been omitted for clarity. (a) View along the a-axis showing solvent-filled channels (acetonitrile molecules shown in brown).  (b) View along the b-axis. Solvent molecules have been omitted for clarity.  (c) View along the c-axis. Solvent molecules have been omitted for clarity.  (d) ORTEP of asymmetric unit, solvent molecules excluded. Ellipsoids are shown at the 50% probability level. Carbon, black; nitrogen, blue; copper, green; iodine, red.  While the triptycenyl quinoxalines 131 and 132 have demonstrated their potential in forming open coordination frameworks, coordinating copper(I) iodide to the phenazines 133- 135 was more difficult. Using the same synthetic strategy for 184•MeCN and 185•2MeCN only resulted in the crystallization of the proligand or the deposition of a colourless powder. 152 Using pure acetonitrile as a solvent also did not result in the desired product; it appears that the phenazines have poor solubility in acetonitrile compared to the quinoxalines. Therefore, benzonitrile was used to promote proligand solubility and when 133 was combined with copper(I) iodide, heated to reflux and allowed to cool slowly, dark red crystals (186•1.5PhCN) formed (Scheme 4.2).   Scheme 4.2.  Preparation of coordination complex 186.  The colour of the product is indicative of reaction between the ligand and metal, and X-ray diffraction of a single crystal provided confirmation of the metal-ligand bonding (Figure 4.3). Surprisingly, 186 is not an extended framework, but instead is a dimer with the two 133 ligands bridged by a Cu2I2 dimer. This is possibly due to the poor solubility of copper(I) iodide in benzonitrile limiting the amount of available copper(I), making it difficult to form an extended network. The solid-state packing arrangement of 186•1.5PhCN has some similarities to its ligand 133, as it also forms a herringbone layered structure with π-stacking. The stacked phenazines are separated by 3.6 Å where the pyrazine rings are over top of each other and the phenyl rings lie on top of each other. Despite this π-stacking, the 186 dimers do not pack together very well, with large solvent-filled voids, with a channel-containing arrangement that is similar to that found for 184•MeCN. This suggests that if the 153 coordination for 133 can be extended, the expected framework should have a similar structure to 184•MeCN.   Figure 4.3.  Solid-state structure of 186•1.5PhCN. Hydrogens have been omitted for clarity. (a) View of single dimer. Ellipsoids are shown at the 50% probability level. Carbon, black; nitrogen, blue; copper, green; iodine, red.  (b) View along the a-axis showing herringbone layered structure. Guest solvent molecules have been omitted for clarity. (c) View along the b-axis showing solvent-filled voids.  Adapted from “Synthesis and Structural Investigation of New Triptycene-Based Ligands: En Route to Shape-Persistent Dendrimers and Macrocycles with Large Free Volume” Chong, J. H.; MacLachlan, M. J. J. Org. Chem. 2007, 72, 8683- 8690. 154  Unfortunately, attempts to form a metal complex using 134 and 135 as ligands have so far been unsuccessful, despite employing a range of solvents and solvent combinations. This is likely due to solubility issues, as the non-polar proligands would be very insoluble in the polar solvents required to solubilize copper(I) iodide and vice versa. Therefore, it is probably not possible to form metal complexes with these ligands using standard benchtop syntheses.  4.3 Guest Exchange Studies  To evaluate their abilities as guest exchange materials, thermogravimetric analysis was performed on 184 and 185 to determine whether they retain their guest solvent and to test their thermal stability. In both cases, the guest solvent in the pores is spontaneously lost upon standing in the atmosphere. Framework 184 is thermally stable to ca. 350 °C, while 185 loses its coordinated acetonitrile when heated above 50 ºC but then remains stable to over 380 °C. Complex 186 does not lose its guest solvent molecules on standing at room temperature, probably due to the high boiling point of benzonitrile. After guest solvent loss, 186 remains thermally stable to  ca. 350 °C, again showing its similarity to 184 (Figure 4.4). 155  Figure 4.4.  Thermogravimetric analysis of 131-135 (heating rate of 10 °C min-1).  It was noted that 184 and 185 maintained their shiny needle-like appearance upon standing on the bench, suggesting that they retained their crystallinity upon solvent loss. Indeed, powder X-ray diffraction confirms that the solid is still crystalline (Figure 4.5b), but it differs from the pattern predicted from the single crystal data (Figure 4.5a). The most notable change is that there is a shift of the (020) peak from 5.60° to 6.20° (2θ) upon solvent loss, suggesting that the lattice of 184 undergoes a small compression but otherwise remains intact. Given that the (CuI)n chain extends along the c-axis and the copper-quinoxaline chain extends along the a-axis, the contraction must take place along the b-axis. A possible scenario for this involves slippage along the a-axis followed by contraction of the b-axis, 156 resulting in interdigitation of the triptycenes and the closure of the channels. This loss of porosity was confirmed by gas adsorption studies that showed no nitrogen uptake by the solvent-free 184. Despite being inacessible to nitrogen molecules, the pores in 184 could still be accessed by organic solvent molecules. When 184 was exposured to acetonitrile vapor, the structure reverted to that predicted for the lattice impregnated with acetonitrile (Figure 4.5c). Pentane and benzene were also adsorbed by 184, resulting in similar crystalline structures to that of the acetonitrile-saturated lattice, (Figure 4.5d-e). The shift of the (020) peak toward smaller angle upon solvent vapour exposure indicates that the original channel structure is regenerated and that the guests are located inside the channels. 157  Figure 4.5.  Powder X-ray diffractograms of 184 evacuated and with various guests:  (a) Predicted spectrum with acetonitrile calculated from single crystal data;  (b) Empty framework;  (c) Adsorption of acetonitrile;  (d) Adsorption of n-pentane  (e) Adsorption of benzene.  Framework 185 is also robust, remaining crystalline after the guest solvent and even the coordinated acetonitrile has been removed from the lattice (Figure 4.6). The lack of similarity between the calculated and experimental spectra indicates a significant change in the lattice upon loss of the acetonitrile molecules. 158  Figure 4.6.  Powder X-ray diffractogram of 185 following heating at 100°C to remove coordinated acetonitrile:  (a) Predicted spectrum calculated from single crystal data without guest acetonitrile present.  (b) Empty framework.  Frameworks 184 and 185 appear to be very hydrophobic since there is no evidence from the thermogravimetric analysis that they absorb water from solvents or the atmosphere. Furthermore, 184 is water-stable, without any visible decomposition or decomposition products observed by 1H NMR spectroscopy after refluxing overnight in D2O. Unlike most other microporous solids, which are either unstable in water or have hydrophilic channels that adsorb water (e.g., zeolites), the properties of 184 present an opportunity to observe guest uptake in water. Framework 184 was effective at removing benzene from D2O as monitored by 1H NMR spectroscopy. A short treatment of the tainted water reduced the dissolved benzene concentration from 0.8 mg mL-1 to < 0.01 mg mL-1 (Figure 4.7).7 After allowing the sample to equilibrate with 184 for 2 days, the level of benzene present was undetectable by 1H NMR spectroscopy. In the treatment with 40 mg of 184, the lattice 159 removes about 0.83 benzene molecules per unit cell, or about 0.1 benzene molecules per Cu atom.8 This verifies the observation from the earlier powder X-ray measurements that the adsorption is internal and is not merely on the surface of the crystallites. Framework 184 does not uptake acetonitrile from water, indicating a selective uptake for non-polar organics. Importantly, 184 can be easily regenerated under vacuum, and even recycled by recrystallization from acetonitrile. With a sorbent capacity of 23.4 mg per g adsorbent, 184 compares favourably to granular activated carbon (GAC-400) and hexadecyltrimethylammonium-modified zeolites with benzene sorbent capacities of 8 and 11.5 mg per g adsorbent, respectively.9   Figure 4.7.  1H NMR measurement of benzene adsorption by 184 after 20, 40, 60, or 80 mg of 184 was added to 1.5 mL of D2O containing 0.01 M benzene. Sucrose was used as an internal standard. 160 4.4 Conclusions  The triptycene-based quinoxalines 131-132 and phenazine 133 prepared in chapter 3 of this thesis were reacted with copper(I) iodide to form complexes 184-186. Complex 186 had a dimeric structure, while 184 and 185 were found to be two-dimensional open coordination frameworks having channels filled with guest solvent molecules. These thermally stable non-interpenetrating coordination frameworks have hydrophobic void spaces and display reversible adsorption of organic solvent vapour, maintaining their crystallinity when evacuated. Framework 184 also removed trace levels of benzene from water, making it a potential adsorbent material for the removal of organic pollutants from contaminated water.  4.5 Experimental  4.5.1 General  Materials.  Compounds 131-135 were prepared as described in Chapter 3 of this thesis. Other reagents were obtained from standard suppliers.  Equipment.  IR spectra were obtained as KBr discs with a Bomems MB-series spectrometer. TGA data was obtained using a Perker Elmer TGA6 instrument. Gas adsorption data was obtained using a Micromeritics ASAP 2000 analyzer and analyses were carried out at 77K.  161 4.5.2 Procedures  Synthesis of 184.  A mixture of compound 131 (0.235 g, 0.77 mmol) and copper(I) iodide (0.292 g, 1.53 mmol) in acetonitrile (125 mL) was heated to reflux. The solvent was partially removed from the clear orange solution by rotary evaporation until red solid began to appear. The solution was heated back to reflux until all the solid dissolved, then was allowed to cool slowly to room temperature, producing red crystals. These were collected by suction filtration, washed with acetonitrile and dried in vacuo to give the product as dark red shiny needles (0.377 g, 72% yield).  Data for 184.  IR ν (KBr) = 3066, 3021, 1481, 1459, 1435, 1367, 1179, 1156, 1045, 890, 743, 629, 588 cm-1.  Anal. Calcd for C22H14N2Cu2I2: C, 38.45; H, 2.05; N, 4.08. Found: C, 38.35; H, 2.17; N, 4.13.  Synthesis of 185.  A mixture of compound 132 (0.240 g, 0.06 mmol) and copper(I) iodide (0.0449 g, 0.24 mmol) in acetonitrile (50 mL) was heated to reflux. The solvent was partially removed from the clear orange solution by rotary evaporation until red solid began to appear. The solution was heated back to reflux until all the solid dissolved, then was allowed to cool slowly to room temperature, producing dark red crystals. These were collected by suction filtration, washed with acetonitrile and air dried to give the product as dark red shiny needles (0.054 g, 79% yield).  162 Data for 185.  IR ν (KBr) = 3438, 1480, 1428, 1364, 1355, 1179, 1083, 1046, 941, 906, 851, 754 cm-1.  Anal. Calcd for C27.2H15.8N6.6Cu4I4 (185•0.6 MeCN): C, 27.30; H, 1.33; N, 7.72. Found: C, 27.63; H, 1.71; N, 7.38. TGA verified that ca. 0.6 MeCN remained in the lattice when analyzed (the physisorbed acetonitrile desorbed slowly at room temperature, but rapidly above 50 ºC).  Synthesis of 186.   A mixture of 133 and copper(I) iodide in benzonitrile was refluxed for 2 h. Slow cooling to room temperature afforded dark red crystals of suitable quality for X-ray diffraction.  Data for 186.  Anal. Calcd for C73H47N2Cu2I2 (186•3PhCN [composition confirmed by TGA]): C, 62.49; N, 6.99; H, 3.38. Found: C, 62.48; N, 6.92; H, 3.48.  Solvent uptake by 184 using PXRD.  A 0.7 mm capillary tube filled with 184 (ca. 5 mg) was placed in a sealed vial containing a saturated atmosphere (25 °C) of solvent (acetonitrile, n-pentane, or benzene) and allowed to stand overnight. The capillary tube was then sealed with a wax plug and an X-ray diffraction pattern was obtained.  Measurement of benzene adsorption by 184.  Twenty-nine milligrams of sucrose and 3.5 μL of benzene were dissolved in 4 mL of D2O. 1.5 mL of the solution was added to each of two NMR tubes, and 1H NMR spectra were obtained for each tube. 184 (20, 40, 60, or 80 mg) was then added to one of the tubes, both tubes (one containing 184 and a control without 184) were shaken for 15 min, and 1H NMR spectra were obtained for each tube. The 163 integration of the benzene signal in each spectrum was calibrated to the area under the proton signals from the hydrogen attached to the anomeric carbon on the pyranose ring. The amount of benzene absorbed by 184 was determined by the decrease in the benzene signal in the treated sample versus the control (untreated) sample after shaking.  4.5.3 X-ray crystallographic analysis  General.  Suitable crystals of compounds 184-186 were mounted on a glass fibre with oil and data for each compound was collected at 173±1 K using graphite monochromated Mo-Kα radiation (λ = 0.71069 Å). Structure solutions were refined using the SHELXL software.10 Crystallographic data for these compounds are tabulated in Appendix 1.  X-ray diffraction study of 184. Crystals of 184 suitable for X-ray diffraction were grown by layering copper(I) iodide in acetonitrile on a solution of 131 in chloroform. All measurements were made on a Rigaku/ADSC diffractometer with data collected in a series of φ and ω scans in 0.50º oscillations with 20 s exposures to a maximum 2θ value of 52.74º. Of the 19632 reflections that were collected, 4612 were unique (Rint = 0.0702); equivalent reflections were merged. The data was collected using d*TREK11 and integrated using the CrystalClear12 software package. Data were corrected for absorption effects using a multi- scan technique (CrystalClear), with max and min transmission coefficients of 1.000 and 0.735, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.13 All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were included in calculated positions but not refined. 164 The final cycle of full-matrix least-squares refinement on F2 was based on 4612 reflections and 270 variable parameters and converged (largest parameter shift was 0.000 times its esd).14  X-ray diffraction study of 185.  Crystals of 185 suitable for X-ray diffraction were grown by layering copper(I) iodide in acetonitrile on a solution of 132 in chloroform. All measurements were made on a Bruker X8 diffractometer with data collected in a series of φ and ω scans in 0.50º oscillations with 12 s exposures to a maximum 2θ value of 47.76º. Of the 21643 reflections that were collected, 5093 were unique (Rint = 0.0390); equivalent reflections were merged. Data were collected and integrated using the Bruker SAINT software package.15 Data were corrected for absorption effects using a multi-scan technique (SADABS)16, with max and min transmission coefficients of 0.883 and 0.552, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.13 All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were included in calculated positions but not refined. The final cycle of full-matrix least- squares refinement on F2 was based on 5093 reflections and 445 variable parameters and converged (largest parameter shift was -0.015 times its esd).14  X-ray diffraction study of 186.  Crystals of 186 suitable for X-ray diffraction were obtained as described in section 5.4.2 of this thesis. All measurements were made on a Bruker X8 diffractometer with data collected in a series of φ and ω scans in 0.50º oscillations with 20 s exposures to a maximum 2θ value of 41.54º. Of the 41747 reflections that were collected, 5186 were unique (Rint = 0.0911); equivalent reflections were merged. Data were collected 165 and integrated using the Bruker SAINT software package.15 Data were corrected for absorption effects using a multi-scan technique (SADABS)16, with max and min transmission coefficients of 0.965 and 0.666, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.13 One of the two benzonitrile molecules in the asymmetric unit was found to be highly disordered. As it was impossible to model this molecule adequately, the SQUEEZE17 function in PLATON6 was used to adjust the data to account for residual electron density found within lattice void spaces. The SQUEEZE output suggests a total of 154 electrons per unit cell were eliminated from the structure, which is equivalent to approximately 0.36 benzonitrile molecules (@ 54 electrons per molecule) per asymmetric unit. All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were located by difference mapping and refined isotropically. The final cycle of full-matrix least-squares refinement on F2 was based on 5186 reflections and 343 variable parameters and converged (largest parameter shift was 0.002 times its esd).14  166 4.6 References  1. (a) Rosi, N. L.; Eckert, J.; Eddaoudi, M.; Vodak, D. T.; Kim, J.; O’Keeffe, M.; Yaghi, O. M. Science 2003, 300, 1127-1129.  (b) Chae, H. K.; Siberio-Pérez, D. Y.; Kim, J.; Go, Y.; Eddaoudi, M.; Matzger, A. J.; O’Keeffe, M.; Yaghi, O. M. Nature 2004, 427, 523-527.  (c) Matsudo, R.; Kitaura, R.; Kitagawa, S.; Kubota, Y.; Belosludov, R. V.; Kobayashi, T. C.; Sakamoto, H.; Chiba, T.; Takata, M.; Kawazoe, Y.; Mita, Y. Nature 2005, 436, 238-241.  (d) Maji, T. K.; Uemura, K.; Chang, H.-C.; Matsuda, R.; Kitagawa, S. Angew. Chem. Int. Ed. 2004, 43, 3269-3272.  (e) Seo, J. S.; Whang, D.; Lee, H.; Jun, S. I.; Oh, J.; Jeon, Y. J.; Kim, K. Nature 2000, 404, 982-986.  (f) Ma, B.-Q.; Mulfort, K. L.; Hupp, J. T. Inorg. Chem. 2005, 44, 4912-4914.  (g) Mircea, D.; Long, J. R. J. Am. Chem. Soc. 2005, 127, 9376-9377.  (h) Wang, Z.; Kravtsov, V.C.; Zaworotko, M. J. Angew. Chem. Int. Ed. 2005, 44, 2877-2880.  (i) Burkholder, E.; Golub, V.; O’Connor, C. J.; Zubieta, J. Inorg. Chem. 2003, 42, 6729-6740.  (j) Papaefstathiou, G. S.; Friščić, T.; MacGillivray, L. R. J. Am. Chem. Soc. 2005, 127, 14160-14161.  (k) Wu, C.-D.; Hu, A.; Zhang, L.; Lin, W. J. Am. Chem. Soc. 2005, 127, 8940-8941. 2. (a) Eddaoudi, M.; Kim, J.; Rosi, N.; Vodak, D.; Wachter, J.; O’Keeffe, M.; Yaghi, O. M. Science 2002, 295, 469-472.  (b) Fournier, J.-H.; Maris, T.; Wuest, J. D. J. Org. Chem. 2004, 69, 1762-1775.  (c) Davidson, D. J. E.; Loeb, S. J. Angew. Chem. Int. Ed. 2003, 42, 74-77. 3. (a) Yang, J.-S.; Swager, T. M. J. Am. Chem. Soc. 1998, 120, 5321-5322. (b) Long, T. M.; Swager, T. M. Adv. Mater. 2001, 13, 601-604.  167  4. (a) Munakata, M.; Wu, L.P.; Sugimoto, K.; Kuroda-Sowa, T.; Maekawa, M.; Suenaga, Y.; Maeno, N.; Fujita, M. Inorg. Chem. 1999, 38, 5674-5680.  (b) Wen, M.; Munakata, M.; Suenaga, Y.; Kuroda-Sowa, T.; Maekawa, M. Inorg. Chim. Acta 2002, 340, 8-14.  (c) Wen, M.; Munakata, M.; Li, Y.-Z.; Suenaga, Y.; Kuroda-Sowa, T.; Maekawa, M.; Anahata, M. Polyhedron 2007, 26, 2455-2460.  (d) Vagin, S.; Ott, A.; Weiss, H.-C.; Karbach, A.; Volkmer, D.; Rieger, B. Eur. J. Inorg. Chem. 2008, 2601- 2609. 5. (a) Graham, P. M.; Pike, R. D.; Sabat, M.; Bailey, R. D.; Pennington, W. T. Inorg. Chem. 2000, 39, 5121-5132. (b) Chesnut, D. K.; Plewak, D.; Zubieta, J. J. Chem. Soc. Dalton Trans. 2001, 2567-2580. 6. Spek, A. L. J. Appl. Cryst. 2003, 36, 7-13. 7. At the concentrations studied (0.8 mg mL-1), benzene was completely dissolved in D2O. Its saturation concentration at 25 ºC is ca. 1.8 mg mL-1 (Source: ChemFinder). 8. When 40 mg of 184 was employed, ca. 1.2x10-5 mol of benzene was adsorbed. Given that each unit cell in 184 has molar mass 2749 (=4x687.26) g mol-1, 40 mg of 184 contains 1.45x10-5 mol of unit cells. Thus, 184 removed ca. 0.83 benzene molecules per unit cell. 9. (a) Simonič, M.; Ozim, V. J. Hazard. Mater. 1998, 60, 205-210.  (b) Altare, C. R.; Bowman, R. S.; Katz, L. E.; Kinney, K. A.; Sullivan, E. J. Microporous Mesoporous Mater. 2007, 105, 305-316. 10. Sheldrick, G. M. Acta Cryst. 2008, A64, 112-122.  168  11. d*TREK. Area Detector Software. Version 7.1I. Molecular Structure Corporation. 2001. 12. CrystalClear 1.3.5 SP2. Molecular Structure Corporation. 2003. 13. SIR92. Altomare, A.; Cascarano, M.; Giacovazzo, C.; Guagliardi, A. J. Appl. Cryst. 1994, 26, 343-350. 14. Least Squares function minimized:   Σw(Fo2-Fc2)2 15. SAINT. Version 6.02. Bruker AXS Inc., Madison, Wisconsin, USA. 1999. 16. SADABS. Bruker Nonius area detector scaling and absorption correction - V2.05, Bruker AXS Inc., Madison, Wisconsin, USA. 17. SQUEEZE. van der Sluis, P.; Spek, A. L. Acta Crystallogr., Sect A 1990, 46, 194- 201. 169 CHAPTER 5 POROUS TRIPTYCENYL METAL SALPHENS WITH INTRINSIC FREE VOLUME †  5.1 Introduction  The environmental impact of fossil fuel combustion is impelling the development of alternative energy sources. Hydrogen combustion is, in principle, a clean source of energy that does not produce carbon dioxide. Incorporating hydrogen fuel into automobiles has many challenges, including the safe and convenient storage of hydrogen onboard vehicles. To be commercially viable, the US Department of Energy has set the hydrogen storage target of 6% by weight by 2010 and 9% by 2015.1  One strategy for improving hydrogen storage uses a porous material to physisorb hydrogen within a tank.2 The high surface area leads to gas adsorption and effectively increases the density of gas storage at a given pressure; heating the material or lowering the pressure will allow the molecules to be controllably desorbed. Several promising materials have been investigated for hydrogen storage, including carbon materials,3 metal-organic frameworks (MOFs),4 covalent organic frameworks (COFs),5 and zeolites.6 All of these  † A version of this chapter will be submitted for publication. Chong, J.H. and MacLachlan, M.J. Triptycene-Based Metal Salphens – Exploiting Intrinsic Molecular Porosity for Gas Storage. 170 materials have extended three-dimensional structures with high surface areas and porosity.7 Although zeolites, MOFs and COFs have uniform porosity, this is not necessarily a requirement for high storage capacity.  Stable, porous molecular solids capable of gas adsorption are far less common, with most of these materials relying on supramolecular assembly, predominantly by hydrogen bonding, to form well-ordered microporous or mesoporous structures.8,9 Although discrete hollow, ring-shaped molecules have intramolecular porosity, it is poor compared to the same molecule in a supramolecular assembly.8a,10 There are no known examples of discrete molecules that exhibit a high level of gas adsorption that is due to intrinsic porosity and not arising from an ordered self-assembled structure.  To develop discrete molecular solids with intrinsic porosity as a new type of porous material, triptycene was identified as an attractive component. In triptycene, "internal molecular free volume" (IMFV) arises from the space between its phenyl rings, created by its rigid structure, that cannot be easily filled by packing.11 This free volume has been successfully exploited to form functional porous polymers and coordination solids,12,13 but its induction of porosity in molecular solids has not been investigated. In fact, although it appears to have IMFV, triptycene itself organizes into a close-packed structure and has no accessible porosity.  171 5.2 Synthesis and Porosity Studies  To perform a systematic study on the effect of IMFV on porosity, a series of compounds with easily varied structures based on nickel salphen (salphen = N,N’- phenylenebis(salicylideneimine)) was developed. The complexes were easily synthesized in a one-pot reaction through standard Schiff-base condensation and salphen metallation. Thus, three diamines (A, 187, 136 or 138) were combined with three salicylaldehyde derivatives (B, 188-190) to generate a total of 9 different nickel salphen complexes (C, 191-199) (Scheme 5.1), with a range of IMFVs (Table 5.1).  NH2 NH2 NH2 NH2 NH2 NH2 H2N H2N H2N NH2 A OH O OH O tBu OH O B 187 136 138 188 189 190 + + x Ni(OAc)2•4H2O C (187,136,138) (188-190) (191-199) Scheme 5.1.  Synthesis of Ni salphens 191-199.  172 N N O O Ni N N O O Ni N N O O Ni R R R R R R 197 R=H 198 R=tBu N N O O Ni N N O O Ni N N O O Ni 199 N N O O Ni R R 191 R=H 192 R=tBu N N O O Ni R R N N O O Ni 193 194 R=H 195 R=tBu N N O O Ni 196   173 Table 5.1.  Synthesis of Ni salphens 191-199 and their properties. C A B x Surface area (m2 g-1) a IMFV (Å3) c 191 187 188 1 Nullb 250 192 187 189 1 Nullb 881 193 187 190 1 40, 61 1944 194 136 188 1 Nullb 1727 195 136 189 1 146, 233 1856 196 136 190 1 216, 311 2154 197 138 188 3 174, 253 2245 198 138 189 3 499, 725 3668 199 138 190 3 403, 592 9761 a  BET and Langmuir surface areas, respectively, determined from N2 adsorption at 77 K. b  N2 isotherm shows that the error is disproportionately high due to low adsorption and consequently surface area data is unreliable. c  Calculated using CPK models with geometry from PM3 calculations.  Thermogravimetric analysis (TGA) indicated that all of the compounds are stable to over 300 °C and most to over 450 °C (Figure 5.1).  174  Figure 5.1.  Thermogravimetric analysis of 191-199 (heating rate of 10 °C min-1).  The effect of different free volumes on porosity was quantified by using gas adsorption to measure accessible surface area and pore size in the molecular solids. Nitrogen adsorption studies of samples, degassed under vacuum at 150 °C overnight, allowed the following conclusions about the relationship between structural characteristics and porosity to be drawn (Table 5.1). Firstly, the presence of a triptycene moiety is required to generate porosity in these salphens as 191 and 192 show no adsorption. However, the mere presence of a triptycene moiety does not guarantee porosity as 194 shows no adsorptive behaviour. Secondly, increasing the number of salphen moieties present in the molecule is an effective means of generating porosity as 197-199, each with three salphen complexes, all have high accessible surface areas. In particular, 198 and 199 have surface areas similar to mesoporous 175 zeolites and around half the surface area of mesoporous silica.14 Each additional salphen has the effect of increasing the length of a triptycene “wing”, producing a greater number of large clefts and therefore increasing IMFV. Thirdly, using a bulky capping salicylaldehyde is also effective in promoting porosity. Combining the bulky triptycenyl salicylaldehyde 190 with the simple diamine 187 yields porous 193, while tert-butylsalicylaldehyde 189 is not sufficient to render 192 porous. Furthermore, 195 and 196 have high surface areas, particularly when their analogue with a non-bulky capping group, 194, has no accessible porosity.  In an effort to correlate the solid’s porosity with the molecule’s IMFV, the IMFV was estimated by subtracting the volume of the molecule from the volume of the smallest bounding prism (Figure 5.2).11,15 Unfortunately this method overestimates IMFV, particularly in the regions near the vertices of the triangular prism. In 191, for instance, there should be no significant IMFV, yet only 53% of its bounding prism is filled by the molecule. Moreover, the calculated IMFV completely neglects intermolecular packing, which may effectively block a substantial amount of the IMFV. Due to these drawbacks, IMFV should only be used as a general guideline in designing systems with intrinsic porosity.  176  Figure 5.2.  Molecular models used to calculate IMFV of  (a) 191  (b) 192  (c) 193  (d) 194 (e) 195  (f) 196  (g) 197  (h) 198  (i) 199.  Carbon, grey; hydrogen, white; nitrogen, blue; oxygen, red; nickel, green. Dimensions of the bounding prisms are in Å.  As Table 5.1 shows, molecules with the smallest IMFVs have the lowest surface areas. Therefore, to design highly porous molecular solids, one should employ molecules that have a large calculated IMFV. Although this is a guiding principle for the development of 177 highly porous molecular solids, the neglect of packing effects leads to exceptions.16 For example, a head-to-tail interdigitation, with one blade occupying the cleft of an adjacent triptycene, effectively fills one of the three triptycene clefts. Compound 199, which has the largest calculated IMFV, has a lower accessible surface area than compound 198, possibly owing to interdigitation.  The shape of the nitrogen adsorption isotherms gives further insight into the nature of the porosity in the molecular solids (Figure 5.3). All the isotherms exhibit inflection points, though the inflection for 193 is very slight. 178  Figure 5.3.  Nitrogen adsorption/desorption isotherms for  (a) 193  (b) 195  (c) 196  (d) 197 (e) 198  (f) 199  at 77 K. Filled circles represent adsorption, open triangles represent desorption.  179 The lack of significant hysteresis in the isotherms for 193 and 196, combined with the presence of inflection points makes them type II isotherms (Figure 5.4a), indicating that that 193 and 196 are macroporous solids. 17 On the other hand, the isotherms for 195 and 197-199 all show significant hysteresis and can be classified as being H4 for 195, 197 and 198, and H2 for 199 (Figure 5.4b). The hysteresis is probably due to the expected swelling that would be observed in a system lacking significant interactions between the individual molecules, allowing the molecules to be pushed apart as more adsorbate molecules condense in the pores. This non-rigid porous arrangement corresponds well with the significant hysteresis that is still present at low pressures. The hysteresis could be very beneficial for gas storage applications since it would allow the gas to be stored at lower pressures following charging, and to be desorbed by other means such as heating. Since the hysteresis is likely due to expansion of the material, the isotherms for 195 and 197-199 should also be designated as type II isotherms, indicating that they are also macroporous materials. 180  Figure 5.4.  International Union of Pure and Applied Chemistry classification of  (a) physisorption isotherms and  (b) hysteresis loops.  Adapted with permission from reference 17. © 1985, the International Union of Pure and Applied Chemistry.  Powder X-ray diffraction (Figure 5.5) shows that most of the salphens retain some crystallinity after solvent removal, though 197-199 are amorphous. In these substances, the observed high porosity is due to only their intrinsic molecular structures that hinder efficient packing and not due to assembly into an ordered porous structure. It is interesting to note that 191, 193, 195 and 196 show considerable crystallinity even after solvent removal. Differential scanning calorimetry (DSC) was performed for 193 and 195-199, particularly to determine whether 197-199 may be in a glassy state, but the DSC traces did not show any glass transitions or melting points.  181  Figure 5.5.  Powder X-ray diffractograms of  (a) 191  (b) 192  (c) 193  (d) 194  (e) 195  (f) 196  (g) 197  (h) 198  (i) 199. 182 A solid-state structure for 197 was determined, using single crystals obtained from DMSO (Figure 5.6). As expected, molecules of 197 are arranged to give a highly porous structure with substantial solvent in the void space. The triptycene moieties effectively prevent close-packing, and there are no significant interactions between the individual molecules in the lattice.   Figure 5.6.  Solid-state structure of 197. Hydrogens have been omitted for clarity.  (a) ORTEP of single molecule. Ellipsoids are shown at the 50% probability level. Carbon, black; nitrogen, blue; oxygen, red; nickel, green.  (b) Extended structure (DMSO molecules shown in brown).  Of particular interest to the field of gas storage materials, McKeown and coworkers have successfully created triptycene-containing tape-like polymers that combine the properties of high surface area and a high density of phenyl rings to produce a hydrogen adsorbing material.12d It was expected that the molecular solids presented in this chapter 183 would be good candidates for hydrogen adsorption since they have metal centres and aromatic ring systems that have both been shown by previous studies to be the sites of hydrogen adsorption in MOFs.18  The ability of salphens 193 and 195-199 to adsorb hydrogen was confirmed with low pressure volumetric methods (Table 5.2). Unexpectedly, the nitrogen accessible surface area was not a predictor of the hydrogen adsorption capacity, since 198 has a greater surface area than 199, yet 198 adsorbs less hydrogen. This may be due to the hydrogen sorbent molecules being able to access small pores in 199 that are not measured by the larger nitrogen molecules. The greater hydrogen storage capacity of 199 may also be due to its increased number of aromatic rings that are known to be beneficial for hydrogen adsorption.4b This adsorptive effect of aromatic rings is also seen in the more efficient adsorption of hydrogen by the “all-triptycene” salphen 196 compared to its tert-butyl capped counterpart 195. The high density of aromatic rings allows salphen 199 to store 1.1 weight % hydrogen at 77 K and 1 atm, similar to the capacity of some MOFs, despite having a much lower surface area.4a  184 Table 5.2.  Hydrogen adsorption properties of salphens 193 and 195-199. Salphen H2 adsorption (cm3 g-1) a Weight% H2 adsorbed a 193 6.7 0.1 195 21.2 0.2 196 52.4 0.5 197 49.8 0.4 198 84.3 0.8 199 121.0 1.1 a  Measured at 1 atm. at 77K.  The hydrogen isotherms for 193 and 195-199 all display type I behaviour (Figure 5.7), which is commonly observed in typical hydrogen adsorption studies since 77 K is too warm for condensation and for the further deposition of hydrogen molecules inside the pores following the initial physisorbed monolayer. Salphens 193 and 195-197 show hysteresis, which is probably due to swelling after saturation with hydrogen. Higher pressures are likely required to produce hysteresis for 198 and 199, as their greater surface areas should result in an increased loading capacity of hydrogen.  185  Figure 5.7.  Hydrogen adsorption/desorption isotherms for (a) 193  (b) 195  (c) 196  (d) 197 (e) 198  (f) 199  at 77 K. Filled circles represent adsorption, open triangles represent desorption.  186 The hydrogen adsorption isotherms and capacities for these compounds suggest that they also have a significant population of micropores. Materials that are reported to demonstrate significant hydrogen adsorption at low pressures (up to 1 atm) are all microporous, as hydrogen adsorption at these pressures and temperatures is favoured by sub- nanometre pores that allow each hydrogen molecule to interact with multiple pore walls. This may be particularly applicable to 198 and 199, which exhibit the greatest amount of hydrogen adsorption, since they have a more gradual increase in nitrogen adsorption at higher pressures. Work is now underway to measure the pore size distribution to further elucidate the nature of the intrinsic porosity of these compounds.  5.3 Conclusions  This chapter presents a novel approach to designing porous solid-state materials that does not rely on the formation of a higher-order structure to achieve high levels of accessible porosity that are comparable with porous supramolecular assemblies. Rather, using discrete molecules where efficient packing is hindered can generate substantial void space and may offer advantages over three-dimensional crystalline frameworks and other materials. The ability of molecular solids to “breathe” by swelling may ultimately increase their gas storage capacities. Moreover, as revealed in by the work in this chapter, molecular compounds can have the thermal stability and high melting points necessary for potential applications. It is expected that this strategy can be employed to create other novel molecules with intrinsic porosity.  187 5.4 Experimental  5.4.1 General  Materials.  Compounds 18919 and 2-methoxy-3-formyltriptycene20 were prepared by literature methods while compounds 136 and 138 were prepared according to Chapter 2 of this thesis. Other reagents were obtained from standard suppliers. All reactions were performed under a nitrogen atmosphere unless otherwise noted. Dichloromethane was dried by passage through a column of activated alumina. Ethanol was degassed by sparging it with nitrogen before use.  Equipment.  1H and 13C NMR spectra were recorded on both Bruker AV-300 and AV-400 spectrometers. 13C NMR spectra were recorded using a proton decoupled pulse sequence. 1H NMR spectra were calibrated to the residual protonated solvent at δ 7.26 ppm, 5.32 ppm and 2.49 ppm in CDCl3, CD2Cl2 and DMSO-d6, respectively. 13C NMR spectra were calibrated to the deuterated solvent at δ 77.00 ppm and 39.52 ppm in CDCl3 and DMSO-d6, respectively. HMQC pulse sequences were used to obtain the chemical shift of the bridgehead carbon in compound 198.21 IR spectra were obtained using attenuated total reflectance with a Thermo Fisher Nicolet 6700 spectrometer.  EI spectra were obtained using a double focusing mass spectrometer (Kratos MS-50) coupled with a MASPEC data system with EI operating conditions of: source temperatures 150-350°C and ionization energy 70 eV. Melting points were obtained on a Fisher-John’s melting point apparatus. TGA data was obtained using a Perker Elmer TGA6 instrument. Powder X-ray diffraction data were obtained with rotating 188 disk samples using a Bruker D8 Advance powder X-ray diffractometer in Bragg-Brentano configuration, under operating conditions of graphite-monochromated Cu-Kα radiation with generator voltage and current of 40 kV and 40 mA and 0.6 mm collimator. Gas adsorption data were obtained using a Micromeritics ASAP 2000 analyzer and analyses were carried out at 77 K.  5.4.2 Procedures  Synthesis of 2-hydroxy-3-formyltriptycene (190).  To a solution of 2-methoxy-3-formyl- triptycene (10.572 g, 33.85 mmol.) in dry dichloromethane (300 mL) cooled in an icebath was added boron tribromide (7 mL, 72.6 mmol.) in 1-2 mL aliquots over ca. 5 mins. The solution was stirred overnight, allowing to warm slowly to room temperature. The reaction was quenched by pouring it into ca. 200 mL water. The layers were separated and the aqueous layer was extracted with dichloromethane (3x100 mL). The combined organic layers were dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation to give a grey solid residue. The residue was flash chromatographed on silica gel with dichloromethane followed by recrystallization from dichloromethane/hexanes to give the desired product as a white solid (5.790 g, 57% yield).  Data for 190.  1H NMR (300 MHz, CDCl3) δ 11.24 (s, 1H, OH), 9.73 (s, 1H, CHO), 7.45 (s, 1H, Ph), 7.42-7.38 (m, 4H, Ph), 7.07-7.03 (m, 5H, Ph), 5.42 (s, 2H, bridgehead) ppm.  13C NMR (100.6 MHz, CDCl3) δ 195.4, 161.0, 154.5, 144.6, 143.3, 136.7, 126.8, 125.8, 125.6, 124.1, 123.5, 116.9, 113.5, 54.3, 52.7 ppm. MS (EI, 70 eV) m/z 298 (M+). IR ν = 2956, 2917, 189 2849, 1651, 1640, 1608, 1580, 1482, 1459, 1377, 1334, 1298, 1256, 1229, 1194, 1156, 1144, 1107, 1073, 1020, 949, 878, 871, 824, 783, 762, 740, 714, 682, 625, 602, 526, 483 cm-1. Mp. = 291-294 °C. Anal. Calcd for C21H14O2: C, 84.54; H, 4.73. Found: C, 84.56; H, 4.72.  General procedure for synthesis of salphens 191-199:  A solution of diamine A (187, 136 or 138), salicylaldehyde B (188-190), and nickel acetate in 30 mL degassed ethanol was refluxed overnight in a nitrogen atmosphere. The cloudy red or orange solution was cooled to room temperature and the precipitate was collected by suction filtration, then washed with solvent to remove excess starting materials, yielding the product as a red or orange solid.  Salphen 191.22  Diamine 187 (0.231 g, 2.14 mmol), salicylaldehyde 188 (0.60 mL, 5.6 mmol), nickel acetate tetrahydrate (0.583 g, 2.34 mmol). Washed with ethanol to give a dark red microcrystalline solid (0.745 g, 93% yield).  Data for 191.  1H NMR (400 MHz, DMSO-d6) δ 8.87 (s, 2H, CHN), 8.15-8.12 (m, 2H, Ph), 7.60 (d, J=8 Hz, 2H, Ph), 7.35-7.30 (m, 4H, Ph), 6.88 (d, J=8 Hz, 2H, Ph), 6.66 (t, J=7 Hz, 2H, Ph) ppm. 13C NMR (100.6 MHz, DMSO-d6) δ 165.3, 156.6, 142.4, 135.3, 134.3, 127.7, 120.3, 120.2, 116.2, 115.4 ppm. IR ν = 3010, 1601, 1574, 1511, 1489, 1455, 1437, 1379, 1371, 1337, 1288, 1263, 1250, 1234, 1192, 1144, 1124, 1047, 1020, 968, 949, 928, 874, 858, 848, 812, 752, 740, 671, 644, 619, 566, 543, 526, 506, 457 cm-1. Mp. >300 °C.  190 Salphen 192.22a  Diamine 187 (0.175 g, 1.62 mmol), salicylaldehyde 189 (0.638 g, 3.58 mmol), nickel acetate tetrahydrate (0.454 g, 1.82 mmol). Washed with ethanol to give a dark red microcrystalline solid (0.657 g, 84% yield). Data for 192.  1H NMR (300 MHz, CDCl3) δ 8.22 (s, 2H, CHN), 7.72-7.69 (m, 2H, Ph); 7.38 (d of d, J=3,12 Hz, 2H, Ph), 7.21-7.18 (m, 4H, Ph), 7.11 (d, J=12 Hz, 2H, Ph), 1.29 (s, 18H, CH3) ppm. 13C NMR (75.4 MHz, CDCl3) δ 165.0, 154.1, 142.8, 138.2, 134.0, 128.0, 127.1, 121.9, 118.9, 114.7, 33.7, 31.2 ppm. IR ν = 2949, 2900, 2862, 1617, 1600, 1574, 1520, 1488, 1455, 1417, 1384, 1357, 1329, 1272, 150, 1225, 1206, 1180, 1163, 1146, 1104, 1045, 937, 827, 737, 722, 609, 570, 541, 452 cm-1. Mp. >300 °C.  Salphen 193.  Diamine 187 (0.052 g, 0.48 mmol), salicylaldehyde 190 (0.320 g, 1.07 mmol), nickel acetate tetrahydrate (0.133 g, 0.54 mmol). Washed with ethanol and dichloromethane to give an orange-red powder (0.343 g, 98% yield).  Data for 193.  1H NMR (400 MHz, DMSO-d6) δ 8.63 (s, 2H, CHN), 8.02-7.99 (m, 2H, Ph), 7.48 (s, 2H, Ph), 7.43 (s, 4H, Ph), 7.27-2.24 (m, 2H, Ph), 7.03-7.01 (m, 4H Ph), 6.99 (s, 2H Ph), 5.51 (s, 2H, bridgehead), 5.50 (s, 2H, bridgehead) ppm. HR-MS (EI, 70 eV) Calcd. for C48H30N2O2Ni: 724.16608; Found: 724.16455.  IR ν = 3017, 2951, 1630, 1601, 1577, 1538, 1513, 1489, 1447, 1434, 1394, 1365, 1312, 1257, 1232, 1196, 1178, 1158, 1108, 1083, 1046, 1022, 939, 903, 882, 872, 865, 852, 802, 784, 749, 737, 711, 699, 659, 634, 624, 615, 574, 488, 475, 451, 423 cm-1. Mp. >300 °C. Too insoluble for 13C NMR.  191 Salphen 194.  Diamine 136 (0.101 g, 0.36 mmol), salicylaldehyde 188 (0.10 mL, 0.94 mmol), nickel acetate tetrahydrate (0.103 g, 0.42 mmol). Washed with ethanol to give a red powder (0.169 g, 87% yield). Data for 194.  1H NMR (400 MHz, CD2Cl2) δ 8.22 (s, 2H, CHN), 7.75 (s, 2H, Ph), 7.46-7.43 (m, 4H, Ph), 7.38 (d of d, J=2,8 Hz, 2H, Ph), 7.29 (t of d, J=2,8 Hz, 2H, Ph), 7.08-7.05 (m, 4H, Ph), 6.97 (d, J=8 Hz, 2H, Ph), 6.67 (t of d, J=1,7 Hz, 2H, Ph), 5.49 (s, 2H, bridgehead) ppm. 13C NMR (75.4 MHz, CDCl3) δ 166.2, 153.4, 145.3, 144.0, 140.1, 135.1, 133.0, 125.8, 123.8, 122.3, 119.8, 116.0, 110.1, 53.9 ppm. HR-MS (EI, 70 eV) Calcd. for C34H22N2O2Ni: 548.10348; Found: 548.10268. IR ν = 3044, 3013, 2950, 1605, 1582, 1558, 1519, 1455, 1444, 1385, 1365, 1333, 1269, 1246, 1210, 1183, 1164, 1148, 1128, 1060, 1022, 942, 915, 846, 834, 806, 747, 737, 672, 655, 642, 625, 606, 590, 569, 535, 485, 473, 459 cm-1. Mp. >300 °C.  Salphen 195.  Diamine 136 (0.102 g, 0.36 mmol), salicylaldehyde 189 (0.173 g, 0.97 mmol), nickel acetate tetrahydrate (0.111 g, 0.45 mmol). Washed with ethanol to give a red solid (0.182 g, 77% yield).  Data for 195.  1H NMR (400 MHz, CDCl3) δ 8.19 (s, 2H, CHN), 7.73 (s, 2H, Ph), 7.41-7.39 (m, 4H, Ph), 7.35 (d of d, J=2,9 Hz, 2H, Ph), 7.21 (d, J=2 Hz, 2H, Ph), 7.08 (d, J=9 Hz, 2H, Ph), 7.06-7.04 (m, 4H, Ph), 5.44 (s, 2H, bridgehead) ppm. 13C NMR (100.6 MHz, CDCl3) δ 164.7, 153.4, 144.8, 144.1, 140.2, 138.3, 127.9, 125.8, 123.7, 121.9, 118.9, 110.0, 53.9, 33.8, 31.2 ppm. HR-MS (EI, 70 eV) Calcd. for C42H38N2O2Ni: 660.22868; Found: 660.22707. IR ν = 2950, 2899, 2861, 1620, 1579, 1520, 1487, 1455, 1417, 1382, 1356, 1328, 1276, 1253, 192 1207, 1178, 1151, 1143, 1106, 1058, 1022, 952, 935, 913, 870, 848, 822, 794, 742, 726, 677, 641, 625, 608, 593, 549, 523, 490, 472, 458 cm-1. Mp. >300 °C. Salphen 196.  Diamine 136 (0.198 g, 0.69 mmol), salicylaldehyde 190 (0.459 g, 1.54 mmol), nickel acetate tetrahydrate (0.193 g, 0.78 mmol). Washed with ethanol and acetone to give a light red-orange powder (0.569 g, 91% yield).  Data for 196.  1H NMR (300 MHz, CDCl3) δ 7.94 (s, 2H, CHN), 7.59 (s, 2H, Ph), 7.40-7.34 (m, 12H, Ph), 7.14 (d, J=5 Hz, 4H, Ph), 7.04-7.00 (m, 12H, Ph), 5.41 (s, 2H, bridgehead), 5.26 (s, 4H, bridgehead) ppm. 13C NMR (100.6 MHz, CDCl3) δ 165.9, 152.0, 151.8, 144.9, 144.5, 144.1, 143.7, 140.0, 132.1, 125.7, 125.6, 125.5, 123.9, 123.7, 123.2, 117.1, 116.3, 109.8, 54.1, 53.9, 52.4 ppm. HR-MS (ESI, MeOH) Calcd. for C62H39N2O2Ni ([M+H]+): 901.2365; Found: 901.2385. IR ν = 3066, 3040, 3018, 2951, 1628, 1604, 1586, 1514, 1482, 1469, 1456, 1446, 1423, 1376, 1362, 1303, 1264, 1238, 1200, 1179, 1159, 1109, 1083, 1061, 1023, 933, 916, 890, 866, 830, 802, 795, 780, 737, 720, 700, 659, 645, 625, 612, 598, 590, 513, 471, 420 cm-1. Mp. >300 °C. Anal. Calcd for C62H40N2O3Ni (12•H2O): C, 80.97; H, 4.38; N, 3.05. Found: C, 80.88; H, 4.34; N, 3.04.  Salphen 197.  Diamine 138 (0.050 g, 0.15 mmol), salicylaldehyde 188 (0.12 mL, 1.1 mmol), nickel acetate tetrahydrate (0.127 g, 0.51 mmol). Washed with ethanol to give a dark red powder (0.104 g, 63% yield).  Data for 197.  1H NMR (400 MHz, DMSO-d6) δ 8.83 (s, 6H, CHN), 8.31 (s, 6H, Ph), 7.57 (d, J=8 Hz, 6H, Ph), 7.31 (t, J=8 Hz, 6H, Ph), 6.86 (d, J=8 Hz, 6H, Ph), 6.68 (t, J=7 Hz, 6H, 193 Ph), 5.73 (s, 2H, bridgehead) ppm. 13C NMR (100.6 MHz, DMSO-d6) δ 165.2, 155.9, 142.8, 140.2, 135.2, 134.1, 120.3, 120.1, 115.3, 111.7, 52.2 ppm. HR-MS (ESI, MeOH) Calcd. for C62H38N6O6Ni3Na ([M+Na]+): 1159.0811. Found: 1159.0840. IR ν = 3050, 3013, 1603, 1581, 1519, 1455, 1440, 1368, 1328, 1268, 1240, 1194, 1147, 1129, 1056, 1023, 942, 926, 895, 848, 814, 751, 738, 711, 671, 652, 605, 571, 529, 473, 453 cm-1. Mp. >300 °C.  Salphen 198.  Diamine 138 (0.050 g, 0.15 mmol), salicylaldehyde 189 (0.175 g, 0.98 mmol), nickel acetate tetrahydrate (0.125 g, 0.50 mmol). Washed with ethanol to give a dark red powder (0.128 g, 60% yield).  Data for 198.  1H NMR (400 MHz, CD2Cl2) δ 8.26 (s, 6H, CHN), 7.83 (s, 6H, Ph), 7.40 (d, J=9 Hz, 6H, Ph), 7.30 (s, 6H, Ph), 6.93 (d, J=9 Hz, 6H, Ph), 5.54 (s, 2H, bridgehead) ppm. 13C NMR (100.6 MHz, CDCl3) δ 165.2, 153.5, 142.4, 141.0, 138.5, 134.4, 127.7, 122.1, 118.8, 110.3, 53.6, 33.8, 31.1 ppm. HR-MS (ESI, MeOH) Calcd. for C86H87N6O6Ni3 ([M+H]+): 1473.4748; Found: 1473.4728. IR ν = 2952, 2901, 2864, 1619, 1582, 1520, 1455, 1416, 1382, 1359, 1323, 1273, 1252, 1179, 1145, 1106, 1058, 1022, 939, 917, 871, 828, 782, 750, 721, 677, 654, 623, 610, 547, 516, 479, 460 cm-1. Mp. >300 °C.  Salphen 199.  Diamine 138 (0.050 g, 0.15 mmol), salicylaldehyde 190 (0.285 g, 0.96 mmol), nickel acetate tetrahydrate (0.125 g, 0.50 mmol). Washed with ethanol and acetone to give a dark red powder (0.195 g, 61% yield).  194 Data for 199.  1H NMR (400 MHz, CDCl3) δ 7.90 (s, 6H, CHN), 7.62 (s, 6H, Ph), 7.34 (d, J=6 Hz, 24H, Ph), 7.11 (d, J=7 Hz, 12H, Ph), 7.05-6.99 (m, 24H, Ph), 5.44 (s, 2H, bridgehead), 5.26 (s, 12H, bridgehead) ppm. 13C NMR (100.6 MHz, CDCl3) δ 166.3, 152.3, 151.9, 144.7, 143.5, 142.2, 140.6, 132.3, 125.6, 124.0, 123.1, 117.2, 116.2, 110.1, 54.0, 52.4 ppm. HR-MS (ESI, MeOH) Calcd. for C146H87N6O6Ni3 ([M+H]+): 2193.4748; Found: 2193.4780. IR ν = 3035, 3015, 2952, 1633, 1582, 1538, 1444, 1457, 1421, 1357, 1300, 1261, 1235, 1195, 1176, 1152, 1109, 1085, 1057, 1022, 928, 916, 875, 833, 802, 736, 649, 625, 614, 595, 469  cm-1. Mp. >300 °C.  5.4.3 X-ray crystallographic analysis  Crystals of 197 suitable for X-ray diffraction were grown from a solution of 197 in DMSO, and a suitable crystal was mounted on a glass fibre with oil. All measurements were made on a Bruker X8 diffractometer with graphite monochromated Mo-Kα radiation (λ = 0.71069 Å). The data were collected at a temperature of 173±1 K in a series of φ and ω scans in 0.50º oscillations with 25 s exposures, to a maximum 2θ value of 46.64º. Of the 79066 reflections that were collected, 13728 were unique (Rint = 0.0871); equivalent reflections were merged. Data were collected and integrated using the Bruker SAINT software package.23 Data were corrected for absorption effects using a multi-scan technique (SADABS),24 with max and min transmission coefficients of 0.985 and 0.731, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods25 and refined using the SHELXL software.26 The material crystallizes with several molecules of DMSO and one molecule of water in the asymmetric unit. Five of these DMSO molecules and the 195 water molecule were found in difference maps and could be adequately modeled and refined with little difficulty. A sixth molecule of DMSO was modeled with a partial occupancy factor of 0.5. The remaining molecules appear to be disordered in multiple orientations.  As it was impossible to model these molecules adequately, the SQUEEZE27 function in PLATON28 was used to adjust the data to account for residual electron density found within lattice void spaces. The SQUEEZE output suggests a total of 285 electrons per unit cell were eliminated from the structure, which is equivalent to approximately 1.5 DMSO molecules (@ 42 electrons per molecule) per asymmetric unit. All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were included in calculated positions but not refined. The final cycle of full-matrix least-squares refinement on F2 was based on 13728 reflections, 915 variable parameters and 6 restraints, and converged (largest parameter shift was 0.009 times its esd).29,30 The crystallographic data is tabulated in Appendix 1.  196 5.5 References  1. Hydrogen, Fuel Cells and Infrastructure Technologies Program: Multiyear Research, Development and Demonstration Plan, US DoE, 2005, http://www1.eere.energy.gov/hydrogenandfuelcells/mypp/. 2. (a) Thomas, K. M. Catal. Today 2007, 120, 389-398.  (b) van den Berg, A. W. C.; Areán, C. O. Chem. Commun. 2008, 668-681. 3. (a) Dillon, A. C.; Jones, K. M.; Bekkedahl, T. A.; Kiang, C. H.; Bethune, D. S.; Heben, M. J. Nature 1997, 386, 377-379.  (b) A. D. Leonard, J. L. Hudson, H. Fan, R. Booker, L. J. Simpson, K. J. O'Neill, P. A. Parilla, M. J. Heben, M. Pasquali, C. Kittrell, J. M. Tour, J. Am. Chem. Soc. 2009, 131, 723-728.  (c) Z. Yang, Y. Xia, R. Mokaya, J. Am. Chem. Soc. 2007, 129, 1673-1679. 4. (a) Rowsell, J. L. C.; Yaghi, O. M. Angew. Chem. Int. Ed. 2005, 44, 4670-4679.  (b) Rosi, N. L.; Eckert, J.; Eddaoudi, M.; Vodak, D. T.; Kim, J.; O'Keeffe, M.; Yaghi, O. M. Science 2003, 300, 1127-1130.  (c) Rowsell, J. L. C.; Millward, A. R.; Park, K. S.; Yaghi, O. M. J. Am. Chem. Soc. 2004, 126, 5666-5667. 5. Han, S. S.; Furukawa, H.; Yaghi, O. M.; Goddard, W. A., III J. Am. Chem. Soc. 2008, 130, 11580-11581. 6. (a) Langmi, H. W.; McGrady, G. S.; Coord. Chem. Rev. 2007, 251, 925-935.  b) Fraenkel, D.; Shabtai, J. J. Am. Chem. Soc. 1977, 99, 7074-7076.  (c) Weitkamp, J.; Fritz, M.; Ernst, S. Int. J. Hydrogen Energy 1995, 20, 967-970.  (d) Langmi, H. W. Walton, A.; Al-Mamouri, M. M.; Johnson, S. R.; Book, D.; Speight, J. D.; Edwards, P. P.; Gameson, I.; Anderson, P. A.; Harris, I. R. J. Alloys Compd. 2003, 356, 710-  197  715.  (e) Regli, L.; Zecchina, A.; Vitillo, J. G.; Cocina, D.; Spoto, G.; Lamberti, C.; Lillerud, K. P.; Olsbye, U.; Bordiga, S. Phys. Chem. Chem. Phys. 2005, 7, 3197- 3203.  (f) Li, Y.; Yang, R. T. J. Phys. Chem. B 2006, 110, 17175-17181. 7. Morris, R. E.; Wheatley, P. S. Angew. Chem. Int. Ed. 2008, 47, 4966-4981. 8. (a) Lim, S.; Kim, H.; Selvapalam, S.; Kim, K.-J.; Cho, S. J.; Seo, G.; Kim, K. Angew. Chem. Int. Ed. 2008, 47, 3352-3355.  (b) Dewal, M. B.; Lufaso, M. W.; Hughes, A. D.; Samuel, S. A.; Pellechia, P.; Shimizu, L. S. Chem. Mater. 2006, 18, 4855-4864. (c) Dalrymple, S. A.; Shimizu, G. K. H. J. Am. Chem. Soc. 2007, 129, 12114-12116. (d) Dewal, M. B.; Xu, Y.; Yang, J.; Mohammed, F.; Smith, M. D.; Shimizu, L. S. Chem. Commun. 2008, 3909-3911.  (e)  Chung, J. W.; Kang, T. J.; Kwak, S.-Y. Langmuir 2007, 23, 12366-12370.  (f) Thallapally, P. K.; McGrail, B. P.; Atwood, J. L.; Gaeta, C.; Tedesco, C; Neri, P. Chem. Mater. 2007, 19, 3355-3357.  (g) Comotti, A.; Bracco, S.; Distefano, G.; Sozzani, P.; Chem. Commun. 2009, 284-286. 9. (a) Couderc, G.; Hertzsch, T.; Behrnd, N.-R.; Krämer, K.; Hulliger, J. Microporous Mesoporous Mater. 2006, 88, 17-175.  (b) Sozzani, P.; Bracco, S.; Comotti, A.; Ferretti, L.; Simonutti, R. Angew. Chem. Int. Ed. 2005, 44, 1816-1820. 10. Miyahara, Y.; Abe, K.; Inazu, T. Angew. Chem. Int. Ed. 2002, 41, 3020-3023. 11. (a) Long, T. M.; Swager, T. M. Adv. Mater. 2001, 13, 601-604.  (b) Tsui, N. T.; Paraskos, A. J.; Torun, L.; Swager, T. M.; Thomas, E. L. Macromolecules 2006, 39, 3350-3358. 12. (a) Yang, J.-S.; Swager, T. M. J. Am. Chem. Soc. 1998, 120, 5321-5322.  (b) Long, T. M.; Swager, T. M. J. Am. Chem. Soc. 2003, 125, 14113-14119.  (c) Rifai, S.; Breen,  198  C. A.; Solis, D. J.; Swager, T. M. Chem. Mater. 2006, 18, 21-25.  (d) Ghanem, B. S.; Msayib, K. J.; McKeown, N. B.; Harris, K. D. M.; Pan, Z.; Budd, P. M.; Butler, A.; Selbie, J.; Book, D.; Walton, A. Chem. Commun. 2007, 67-69. 13. Vagin, S.; Ott, A.; Weiss, H.-C.; Karbach, A.; Volkmer, D.; Rieger, B. Eur. J. Inorg. Chem. 2008, 2601-2609. 14. (a) Tao, Y.; Kanoh, H.; Abrams, L.; Kaneko, K. Chem. Rev. 2006, 106, 896-910.  (b) Yanagisawa, T.; Shimizu, T.; Kuroda, K.; Kato, C. Bull. Chem. Soc. Jpn. 1990, 63, 988-992.  (c) Kresge, C. T.; Leonowicz, M. E.; Roth, W. J.; Vartuli, J. C.; Beck, J. S. Nature 1992, 359, 710-712. 15. Hilton, C. L.; Jamison, C. R.; Zane, H. K.; King, B. T. J. Org. Chem. 2009, 74, 405- 407. 16. (a) Venugopalan, P.; Bürgi, H.-B.; Frank, N. L.; Baldridge, K. K.; Siegel, J. S. Tetrahedron Lett. 1995, 36, 2419-2422.  (b) Yang, J.-S.; Liu, C.-P.; Lin, B.-C.; Tu, C.-W.; Lee, G.-H. J. Org. Chem. 2002, 67, 7343-7354. 17. Sing, K. S. W.; Everett, D. H.; Haul, R. A. W.; Moscou, L.; Pierotti, R. A.; Rouquérol, J.; Siemieniewska, T. Pure Appl. Chem. 1985, 57, 603-619. 18. (a) Rowsell, J. L. C.; Eckert, J.; Yaghi, O. M. J. Am. Chem. Soc. 2005, 127, 14904- 14910.  (b) Spencer, E. C.; Howard, J. A. K.; McIntyre, J. A. K.; Rowsell, J. L. C.; Yaghi, O. M. Chem. Commun. 2006, 278-280. 19. Knight, P. D.; O’Shaughnessy, P. N.; Munslow, I. J.; Kimberley, B. S.; Scott, P. J. Organomet Chem. 2003, 683, 103-113. 20. Iwata, M.; Emoto, S. Bull. Chem. Soc. Jpn. 1974, 47, 1687-1692.  199  21. This carbon appears to have a very long T1 relaxation time, and was not observed in a one dimensional spectrum even after an extended duration. 22. (a) Escudero-Adan, E. C.; Benet-Buchholz, J.; Kleij, A. W. Inorg. Chem. 2007, 46, 7265-7267.  (b) Di Bella, S.; Fragala, I.; Ledoux, I.; Diaz-Garcia, M. A.; Marks, T. J. J. Am. Chem. Soc. 1997, 119, 9550-9557. 23. SAINT. Version 6.02. Bruker AXS Inc., Madison, Wisconsin, USA. (1999). 24. SADABS. Bruker Nonius area detector scaling and absorption correction - V2.05, Bruker AXS Inc., Madison, Wisconsin, USA. 25. SIR92: Altomare, A.; Cascarano, M.; Giacovazzo, C.; Guagliardi, A. J. Appl. Cryst. 1994, 26, 343-350. 26. Sheldrick, G. M. Acta Cryst. 2008, A64, 112-122. 27. SQUEEZE - van der Sluis, P.; Spek, A. L. Acta Crystallogr., Sect A 1990, 46, 194- 201. 28. PLATON, A Multipurpose Crystallographic Tool, Utrecht University, Utrecht, The Netherlands, Spek, A. L. (1998). 29. Sheldrick, G. M. SHELXL-97. Programs for Crystal Structure Analysis (Release 97- 2). University of Göttingen, Germany (1997). 30. Least Squares function minimized: Σw(Fo2-Fc2)2 200 CHAPTER 6 CONCLUSIONS AND FUTURE DIRECTIONS  6.1 Overview  Recent research into triptycene-containing materials has centred on the use of triptycene to generate porosity by the disruption of efficient packing caused by their rigid geometry.1 The work presented in this thesis aims to develop new methodologies for generating functional porous materials by utilizing triptycene-based building blocks. A set of synthetic methodologies was developed to reach a series of triptycenyl o-phenylenediamines and o-quinones. Beginning with triptycene, a double nitration/reduction strategy was employed to introduce amino groups at the desired beta positions and give triptycenes with varying numbers of amino groups (136-138). The triptycene-based o-quinones (139 and 162) were easily prepared by oxidative demethylation of their precursor o-dimethoxy compounds using cerium ammonium nitrate. Unlike typical o-quinones, triptycene-based o-quinones exhibit a high degree of stability due to the rigid geometry of triptycene being able to prevent intermolecular dimerization by a Diels-Alder reaction. The rigid geometry of triptycene also facilitates orbital overlap and electronic communication between the aromatic rings, allowing redox reactions to take place in a stepwise manner. This stepwise mechanism can be exploited to isolate partially oxidized intermediates with varying numbers of quinone moieties. The electronic communication in the triptycenes can be used to prepare stable 201 compounds bearing both o-dihydroxy and o-quinone moieties in the same molecule without using protecting groups (174).    These o-phenylenediamines and o-quinones provide the means to construct a variety of rigid, shape-persistent molecules that have reduced packing efficiencies. The triptycenyl phenylenediamines are especially versatile as they can undergo Schiff-base condensation to form numerous quinoxaline, phenazine and salphen proligands. These compounds can coordinate metals to form highly stable coordination frameworks and complexes that exhibit a high degree of porosity in the solid state. Their porous nature also makes them functional materials capable of reversibly adsorbing various guests ranging from gases to organic solvents.  202 6.2 Pyrazine-Copper Metal-Organic Frameworks  The phenylenediamines 136 and 138 can undergo Schiff base condensation with a glyoxal equivalent or with quinone 139 to form a series of triptycene-based quinoxalines (131 and 132) and phenazines (133-135), bearing either one or three pyrazine rings. Structural studies by single crystal X-ray crystallography demonstrated that increasing the number and size of the triptycene “wings” decreases packing efficiency and generates structures with solvent-filled voids. The presence of triptycenes has also been shown to convert quinoxaline-copper extended coordination frameworks from close-packed solids to highly porous frameworks containing solvent-filled channels (184 and 185). While a strongly coordinated three-dimensional structure is usually needed to maintain stability when guests are removed, the frameworks in this thesis remained crystalline upon removal of the guest acetonitrile, although there was contraction of the structure due to the collapse of the channels. Remarkably, exposure of the solvent-free 184 to acetonitrile vapour resulted in solvent uptake, regenerating the original framework with the solvent-filled channels. Framework 184 was also capable of adsorbing other organic solvent vapours, also resulting in an expansion to give similar channel-containing structures. Unlike most coordination frameworks, 184 has the rare property of being highly resistant to hydrolysis and was used to selectively remove trace quantities of benzene from contaminated water. The reversible nature of the benzene adsorption allows 184 to be regenerated by facile evacuation of the solvent-laden solid and to be reused multiple times.  203   6.3 Nickel Salphens  The triptycene-based phenylenediamines 136 and 138, and the parent o- phenylenediamine, were condensed with a variety of salicylaldehyde derivatives, including the triptycene-based 190, to prepare a series of nickel salphens (191-199). While internal free volume is an important concept in iptycene chemistry, there has been no systematic study on how internal free volume translates into accessible porosity. The nickel salphens in this thesis provided the ideal opportunity to study this matter due to their varying molecular geometries and amounts of internal free volume through gas adsorption. While many solids rely on supramolecular ordering to generate porosity, the porosity of these salphens comes solely 204 from the intrinsic porosity of each molecule created by their inability to pack together efficiently and fill the void space in the triptycene clefts. It was found that compounds with larger amounts of internal free volume tend to have greater amounts of porosity, but this relationship cannot be quantified since some of the compounds with relatively low internal free volume had no measurable porosity. The presence of triptycenes is highly effective at generating porosity, as increasing the triptycene content increases the porosity. In particular, salphens 198 and 199 have significant porosities, having measurable surface areas in excess of 400 m2 g-1.  N N O O Ni N N O O Ni N N O O Ni tBu tBu tBu tBu tBu tBu 198 N N O O Ni N N O O Ni N N O O Ni 199   Unlike supramolecular materials, the lack of strong intermolecular interactions results in expansion of these materials at higher adsorbate pressures, generating hysteresis in their adsorption profiles that is retained until very low pressures. These porous solids also demonstrate the ability to adsorb hydrogen reversibly at 77 K, with 199 storing around 1 % 205 of hydrogen by weight. Their hydrogen adsorption capabilities, adsorption/desorption hysteresis and high thermal stabilities gives them the potential to be used as hydrogen storage materials where the hydrogen can be loaded under pressure but controllably desorbed by other means (e.g., heating of the storage system). Therefore, triptycenes offer a new approach to generating porous functional materials that rely only on the design of the individual molecule, without having to rely on having functional groups at specific geometries to form supramolecular structures.  6.4 Future Directions  6.4.1 Molecular architectures  From the work carried out in this thesis, it is clear that triptycene-based compounds can be used to induce and control a compound’s porosity in the solid state. In particular, triptycene is an excellent scaffold from which shape-persistent metal-organic frameworks can be built due to its rigidity. It is possible to envisage self-assembled molecular hexagons or extended honeycombs containing triptycenes, where the bridgehead carbons are sited at the vertices to take advantage of the 120° angles between the phenyl rings. Schiff base condensation does not appear to be an effective method to join the triptycene-containing building blocks together due to the formation of byproducts (Chapter 3), but metal coordination presents another opportunity. o-Phenylenediamines themselves are capable of metal coordination with the group 10 metals to form square planar complexes.2 Similarly, coordination of the group 10 metals by 137 and 138 could be used to form the desired 206 hexagonal and honeycomb architectures, respectively. To demonstrate the potential feasibility of this approach, diamine 136 was reacted with potassium tetrachloroplatinate to form 200, a model compound representing a side wall of the hexagon or honeycomb (Scheme 6.1).   Scheme 6.1.  Preparation of model complex 200.  A solid-state structure of the resulting dark blue product shows the expected square planar geometry that is consistent with the structure previously obtained for the parent o- phenylenediamine (Figure 6.1a).2 The extended structure again shows the influence of triptycenes on decreasing the packing efficiency, leading to the formation of solvent-filled channels extending along the direction of the a-axis (Figure 6.1b); these channels separate the layers composed of molecules of 200 (Figure 6.1c). Since 200 can be formed, it is expected that 137 and 138 could be used to form the desired molecular hexagon and honeycomb. If the coordination is carried out in a stepwise manner, 138 could be used to form rigid triptycene-containing dendrimers.  207  Figure 6.1.  Solid-state structure of 200. Hydrogens have been omitted for clarity.  (a) ORTEP of single molecule. Ellipsoids are shown at 50% probability. Carbon, black; nitrogen, blue; platinum, brown.  (b) View along a-axis (DMSO molecules shown in green). (c) View along b-axis (DMSO molecules shown in green).  6.4.2 Phenazine-copper frameworks  The triptycene-based phenazines 133-135 have the potential to form extended coordination frameworks similar to those formed by quinoxalines 131 and 132. Since 133 forms the dimeric complex 186, the ability to coordinate copper(I) is not affected by any electronic differences between the quinoxalines and the phenazines. The main obstacle to forming coordination frameworks involving 133-135 is the difference in solubility between the proligands and the copper salt. The presence of an extra phenyl ring greatly decreases the 208 solubility of the phenazines in acetonitrile, requiring the use of the more non-polar solvent benzonitrile in the case of 133. However, such solvents decrease the solubility of copper(I) iodide, limiting the amount of copper available for coordination, resulting in the dimeric complex 186 instead of the expected extended framework.  To deal with this problem, conditions need to be found in which both the phenazine proligands and the copper salt have sufficient solubility. There appears to be no readily available solvent that would meet this criterion, but solubility increases with temperature. Therefore, a hydrothermal synthetic approach using acetonitrile may result in the desired coordination frameworks. This method could also be used for generating frameworks using the less soluble copper bromide and chloride salts to determine if the structure of the frameworks can be tuned by altering the counterion used.  6.4.3 Nickel salphens  The triptycene-containing nickel salphens presented in chapter 5 of this thesis show great promise as a means of generating porous materials through their intrinsic molecular porosity, without relying on the formation of ordered structures. There is the need for further investigation in this area to determine the relationship between their structures and accessible porosity. One method of generating further structural variation is to use 137 in combination with the existing library of salicylaldehydes to form another three salphens that will each have two salphen moieties.  209 An alternative way to generate new salphens is to introduce additional salicylaldehydes. The large salicylaldehyde 190 has been very effective at generating salphens with large amounts of intrinsic porosity. If this salicylaldehyde could be enlarged, salphens with even more porosity would be expected. One method of carrying this out would be to use a di-tert-butyl derivative (205). Although these compounds have not been reported, a synthetic route can be easily devised (Scheme 6.2). Anthracene 2013 can be used as the diene in a Diels-Alder reaction with the appropriate bromobenzyne to give 202. Substitution of the bromine atom through an Ullman-type reaction should produce 203, which can then be formylated using Vilsmeier-Haack conditions to give 204,4 followed by demethylation to yield the desired salicylaldehyde 205.   Scheme 6.2.  Proposed synthetic route to salicylaldehyde 205.  210 The tert-butyl groups on 205 should not only serve to increase the porosity of the resulting salphens, but will also improve their solubility. The triptycene will hinder efficient packing and the tert-butyl groups will provide multiple degrees of freedom; dealing with solubility is important for large, rigid compounds.  6.4.4 Porous Prussian Blue analogues  Novel mesoporous Prussian Blue analogues formed using liquid crystalline templates have recently been reported, but it is difficult to remove the templating molecules trapped in the mesopores.5 Using triptycene-based proligands would provide another strategy for forming porous Prussian Blue analogues, using the ability of triptycenes to hinder efficient packing. To carry this out, the triptycene-based phenanthroline proligands 206-208 were prepared by Schiff-base condensation of the commercially available phenanthroline quinone with 136-138, respectively (Scheme 6.3).  211 N N N N N N N N N N O O EtOH N N O O EtOH 206 207 NH2 136 NH2 NH2 137 NH2 H2N H2N N N N N N N N N N N N N N N O O EtOH 208 NH2 138 NH2 H2N H2N H2N NH2 N N N N  Scheme 6.3.  Synthesis of triptycene-based phenanthrolines 206-208.  A solid-state structure was obtained for 206, which confirms the expected molecular structure (Figure 6.2a). The extended packing arrangement shows partial overlap of the aromatic rings in the phenanthroline moiety, with the rings separated by approximately 3.4 Å, which is an optimal distance for π-stacking (Figure 6.2b-c). These stacks extend along the direction of the a-axis (Figure 6.2d). While stacking typically improves solid-state packing efficiency, the triptycenes prevent the stacks from adopting a close-packed structure, with the 212 stacks themselves arranged in an undulating manner. The unfilled space between the stacks contains guest methanol molecules, producing solvent-filled channels that extend along the direction of the a-axis (Figure 6.2e). 213  Figure 6.2.  Solid-state structure of 206. Hydrogens have been omitted for clarity.  (a) ORTEP of single molecule. Ellipsoids are shown at the 50% probability level. Carbon, black; nitrogen, blue.  (b) View showing stacking of molecules.  (c)  Side view of a pair of stacked molecules.  (d) View down c-axis showing stacks extending along the a-axis. Guest solvent has been omitted for clarity.  (e) View down a-axis showing solvent-filled channels (methanol molecules shown in red). 214  To synthesize the desired Prussian Blue analogues, hydrothermal methods were employed due to the insolubility of the proligands at ambient temperatures. Initial attempts focused on combining the proligand, copper(II) chloride and potassium hexacyanoferrate in a one pot synthesis, resulting in multiple products; a mixture of purple needles (209), red plates (210) and brown cubes (211) were observed when proligand 206 was used. X-ray diffraction was performed on the purple needles, using synchrotron radiation due to the extremely small size of the needles. The solid-state structure of 209 shows two 206 ligands chelating a copper atom; the pseudo-tetrahedral geometry at the metal centres and the presence of one [CuCl2]- charge-balancing counterion per chelated metal centre is consistent with the chelated copper atom being in the 1+ oxidation state (Figure 6.3a). An extended structure shows a certain amount of overlap between the phenanthrolines, though there is a slight deviation from coplanarity, linking them into stacks along the direction of the b-axis (Figure 6.3b). The presence of the triptycenes hinders packing, resulting in void channels running along the direction of the b-axis (Figure 6.3c). The voids are partially filled by the [CuCl2]- counterions, but apart from a single small peak of residual electron density, there is nothing to suggest the presence of other ordered guests. Since the presence of large unfilled voids is unfavourable, it is likely that these areas are occupied by completely disordered guest solvent molecules that are not observed by X-ray diffraction.  215  Figure 6.3.  Solid-state structure of 209. Hydrogens have been omitted for clarity. Carbon, black; nitrogen, blue; copper, brown; chlorine, green.  (a) ORTEP of single molecule. Ellipsoids are shown at the 50% probability level.  (b) View of stacked molecules.  (c) View down the b-axis showing channels.  The red plates were also studied by X-ray diffraction but the quality of the resulting data set was quite poor, preventing adequate refinement of the structure. However, the preliminary solution allows the cell contents and connectivity of 210 to be determined (Figure 6.4a). Although reaction mixture contained potassium hexacyanoferrate(III), copper is the only metal present in the structure. There are three different copper centres, with linear, 216 pseudo-trigonal planar and pseudo-tetrahedral geometries. The tricoordinate copper centre is chelated by a phenanthroline and also coordinates a chloride ligand. The pseudo-tetrahedral metal centre is also chelated by a phenanthroline and has two cyanide ligands. An extended structure shows that the linear and the pseudo-tetrahedral copper centres are linked by cyanide ligands into an infinite chain extending in the direction of the c-axis (Figure 6.4b). The linear copper centres are connected on both sides to a pseudo-tetrahedral copper centre. However, the pseudo-tetrahedral coppers are linked to a linear copper and to another pseudo- tetrahedral copper. Due to the poor data quality, it was not possible to confirm the orientation of the cyanide ligands in the structure and whether each copper centre is N-bound or C- bound. The phenanthroline ligand that coordinates the trigonal planar copper centre is intercalated between the phenanthrolines involved in the coordination polymer, probably due to interactions from π-orbital overlap. 217  Figure 6.4.  Preliminary solid-state structure of 210. Carbon, black; nitrogen, blue; copper, brown; chlorine, green.  (a) Asymmetric unit.  (b) View down the a-axis.  Knowing the composition of 209, it should be possible to prepare this compound directly using copper(I) chloride to generate a single product, without involving reduction of copper(II) (Scheme 6.4). Reacting 209 with copper cyanide should result in 210, and this stepwise synthetic approach may assist in obtaining higher quality single crystals to determine the true structure of 210. Alternatively, reacting 209 with hexacyanoferrate(III) salts may generate the desired porous Prussian Blue analogues.  218  Scheme 6.4.  Proposed synthetic route to complex 209.  6.5 Experimental  6.5.1 General  Materials.  Compounds 136-138 were prepared as described in Chapter 2 of this thesis. Other reagents were obtained from standard suppliers. All reactions were performed under a nitrogen atmosphere. Solvents were degassed by sparging them with nitrogen before use.  Equipment.  1H and 13C NMR spectra were recorded on a Bruker AV-300 spectrometer. 13C NMR spectra were recorded using a proton decoupled pulse sequence. 1H NMR spectra were calibrated to the residual protonated solvent at δ 7.26 and 5.32 ppm in CDCl3 and CD2Cl2, respectively. 13C NMR spectra were calibrated to the deuterated solvent at δ 77.00 ppm in CDCl3. IR spectra were obtained using attenuated total reflectance with a Thermo Fisher 219 Nicolet 6700 spectrometer. EI spectra were obtained using a double focusing mass spectrometer (Kratos MS-50) coupled with a MASPEC data system with EI operating conditions of: source temperatures 250-320 °C and ionization energy 70 eV. Melting points were obtained on a Fisher-John’s melting point apparatus. ESI mass spectra were obtained on a Waters/Micromass LCT time-of-flight mass spectrometer equipped with an electrospray ion source.  6.5.2 Procedures  Synthesis of complex 200.  A solution of 136 (0.068 g, 0.24 mmol) and potassium tetrachloroplatinate (0.047 g, 0.11 mmol) in methanol (5 mL) was heated overnight at 70 ºC. After cooling to room temperature, the precipitate was collected by suction filtration and washed with ethanol to give the desired product as a dark blue solid (0.024 g, 28% yield).  Data for 200.  1H NMR (300 MHz, DMSO-d6) δ 8.01 (br s, 2H, NH), 7.45-7.42 (m, 8H, Ar), 7.39 (s, 4H, Ar), 7.01-6.98 (m, 8H, Ar), 5.75 (s, 4H, bridgehead) ppm.  IR ν = 3035, 1614, 1537, 1456, 1417, 1336, 1227, 1201, 1182, 1155, 870, 794, 771, 748, 724, 659, 639, 624, 597, 484 cm-1.  Mp. > 300 °C.  Synthesis of triptycenyl phenanthroline (206).  A solution of 136 (0.200 g, 0.70 mmol) and phenanthroline quinone (0.171 g, 0.81 mmol) in ethanol (40 mL) was refluxed overnight. After cooling to room temperature, the precipitate was collected by suction filtration and 220 washed with ethanol. Vacuum drying yielded the desired product as a pale yellow solid (0.260 g, 81% yield).  Data for 206. 1H NMR (400 MHz, CDCl3) δ 9.57 (d of d, J=2,8 Hz, 2H, Ar), 9.22 (d of d, J=2,4 Hz, 2H, Ar), 8.24 (s, 2H, Ar), 7.74 (d of d, J=4,8 Hz, 2H, Ar), 7.54-7.52 (m, 4H, Ar), 7.13-7.10 (m, 4H, Ar), 5.74 (s, 2H, bridgehead) ppm.  13C NMR (100.6 MHz, CDCl3) δ 152.1, 147.9, 147.0, 143.5, 141.6, 140.2, 133.3, 127.4, 126.2, 124.1, 123.8, 122.7, 53.7 ppm. HR-MS (EI, 70 eV) Calcd. for C32H18N4: 458.15315; Found: 458.15394.  IR ν = 3350, 2967, 1574, 1479, 1448, 1430, 1401, 1358, 1336, 1315, 1273, 1150, 1122, 1109, 1071, 1053, 1029, 893, 807, 767, 749, 736, 628, 597, 564, 492, 481 cm-1.  Mp. > 300 °C.  Synthesis of triptycenyl bis(phenanthroline) (207).  A solution of 137 (0.095 g, 0.30 mmol) and phenanthroline quinone (0.142 g, 0.68 mmol) in ethanol (40 mL) was refluxed overnight. After cooling to room temperature, the precipitate was collected by suction filtration and washed with ethanol. Vacuum drying yielded the desired product as a light brown, shiny solid (0.186 g, 93% yield).  Data for 207. 1H NMR (400 MHz, CD2Cl2) δ 9.61 (d of d, J=2,8 Hz, 4H, Ar), 9.18 (d of d, J=2,5 Hz, 4H, Ar), 7.77 (d of d, J=5,8 Hz, 4H, Ar), 7.71-7.68 (m, 2H, Ar), 7.24-7.22 (m, 2H, Ar), 6.13 (s, 2H, bridgehead) ppm.  13C NMR (100.6 MHz, CDCl3) δ 152.4, 145.4, 142.1, 141.8, 140.8, 133.6, 127.5, 127.1, 125.6, 124.6, 124.1, 123.7, 53.5 ppm.  HR-MS (EI, 70 eV) Calcd. for C44H22N8: 662.19674; Found: 662.19507.  IR ν = 3360, 1633, 1574, 1478, 1448, 221 1418, 1402, 1358, 1337, 1228, 1197, 1165, 1149, 1128, 1107, 1070, 1030, 890, 808, 760, 738, 629, 608, 593, 564, 490 cm-1.  Mp. > 300 °C.  Synthesis of triptycenyl tris(phenanthroline) (208).  A solution of 138 (0.100 g, 0.29 mmol) and phenanthroline quinone (0.197 g, 0.94 mmol) in ethanol (30 mL) was refluxed overnight. After cooling to room temperature, the precipitate was collected by suction filtration and washed with ethanol. Vacuum drying yielded the desired product as a brown solid (0.137 g, 54% yield).  Data for 208. 1H NMR (400 MHz, CDCl3) δ 9.64 (d of d, J=2, 8 Hz, 6H, Ar), 9.26 (d of d, J=2, 4 Hz, 6H, Ar), 7.80 (d of d, J=4 Hz, 8 Hz, 6H, Ar), 6.41 (s, 2H, bridgehead) ppm.  HR- MS (ESI, MeOH) Calcd. for C56H27N12: 867.2482 ([M+H]+); Found: 867.2499.  IR ν = 3390, 1633, 1537, 1478, 1447, 1402, 1357, 1338, 1228, 1198, 1123, 1070, 1030, 889, 807, 740, 616, 597, 564, 491 cm-1.  Mp. > 300 °C.  Too insoluble for 13C NMR.  Synthesis of 209, 210 and 211.  Proligand 206 (7.8 mg, 0.017 mmol), copper(II) chloride dihydrate (2.9 mg, 0.017 mmol), potassium hexacyanoferrate (5.6 mg, 0.017 mmol) and methanol (10 mL) were loaded in a Parr pressure vessel, equipped with a Teflon liner. The sealed vessel was heated to 180 °C in an oven. After 48 h, the reaction was cooled down to room temperature at a rate of 6 °C h-1. Purple needles (209), red plates (210) and brown cubes (211) were isolated.  222 6.5.3 X-ray crystallographic analysis  General.  Suitable crystals of compounds 200, 206, 209 and 210 were mounted on a glass fibre with oil. Structure solutions were refined using the SHELXL software.6 Crystallographic data for these compounds are tabulated in Appendix 1.  X-ray diffraction study of 200.  Crystals of 200 suitable for X-ray diffraction were grown by slow cooling of a solution of 200 in hot DMSO. All measurements were made on a Bruker X8 diffractometer at 173±1 K using graphite monochromated Mo-Kα radiation (λ = 0.71069 Å). Data was collected to a maximum 2θ value of 52.96º in a series of φ and ω scans in 0.50º oscillations with 20 s exposures. Of the 41855 reflections that were collected, 4676 were unique (Rint = 0.0316); equivalent reflections were merged. Data were collected and integrated using the Bruker SAINT software package.7 Data were corrected for absorption effects using a multi-scan technique (SADABS)8, with max and min transmission coefficients of 0.725 and 0.464, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.9 The material crystallizes with two molecules of DMSO in the asymmetric unit. One of these DMSO molecules could be adequately modeled and refined with little difficulty, but the other DMSO molecule appears to be disordered in multiple orientations. As it was impossible to model this molecule adequately, the SQUEEZE10 function in PLATON11 was used to adjust the data to account for residual electron density found within lattice void spaces. The SQUEEZE output suggests a total of 181 electrons per unit cell were eliminated from the structure, which is equivalent to approximately 2 DMSO molecules (@ 42 electrons per molecule) per 223 asymmetric unit. All non-hydrogen atoms were refined anisotropically. The hydrogen atoms attached to the nitrogens were located by difference mapping and refined isotropically; all other hydrogens were included in calculated positions but were not refined. The final cycle of full-matrix least-squares refinement on F2 was based on 4676 reflections and 256 variable parameters and converged (largest parameter shift was 0.001 times its esd).12  X-ray diffraction study of 206.  Crystals of 206 suitable for X-ray diffraction were grown by slow cooling of a solution of 206 in methanol heated in a sealed pressure vessel. All measurements were made on a Bruker X8 diffractometer at 173±1 K using graphite monochromated Mo-Kα radiation (λ = 0.71069 Å). Data was collected to a maximum 2θ value of 51.34º in a series of φ and ω scans in 0.50º oscillations with 60 s exposures. Of the 40914 reflections that were collected, 8505 were unique (Rint = 0.0810); equivalent reflections were merged. Data were collected and integrated using the Bruker SAINT software package.7 Data were corrected for absorption effects using a multi-scan technique (SADABS)8, with max and min transmission coefficients of 0.996 and 0.858, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.9 All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were included in calculated positions but not refined. The final cycle of full-matrix least- squares refinement on F2 was based on 8505 reflections and 668 variable parameters and converged (largest parameter shift was 0.000 times its esd).12  X-ray diffraction study of 209.  Crystals of 209 suitable for X-ray diffraction were obtained according to the procedure in section 6.5.2 of this thesis. Intensity data were collected at 224 150K on a D8 goniostat equipped with a Bruker APEX II CCD detector at Beamline 11.3.1 at the Advanced Light Source (Lawrence Berkeley National Laboratory)13 using synchrotron radiation tuned to λ=0.7749Å, detector-to-crystal distance=6 cm. A series of 4 s data frames measured at 0.2o increments of ω were collected to calculate a unit cell. For data collection frames were measured for a duration of 4 s at 0.3o intervals of ω with a maximum 2θ value of ~60o. The data frames were collected using the program APEX214 and processed using the program SAINT15 routine within APEX2. Of the 63492 reflections that were collected, 12459 were unique (Rint = 0.0948); equivalent reflections were merged. The data were corrected for absorption and beam corrections based on the multi-scan technique as implemented in SADABS8, with max and min transmission coefficient of 0.990 and 0.806, respectively. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.9 All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were included in calculated locations but were not refined. The final cycle of full-matrix least-squares refinement on F2 was based on 12459 reflections, 1369 variable parameters and 2 restraints, and converged (largest parameter shift was 0.001 times its esd).12  X-ray diffraction study of 210.  Crystals of 210 suitable for X-ray diffraction were were obtained according to the procedure in section 6.5.2 of this thesis. All measurements were made on a Bruker X8 diffractometer at 173±1 K using graphite monochromated Mo-Kα radiation (λ = 0.71069 Å). Data was collected to a maximum 2θ value of 45.08º in a series of φ and ω scans in 0.50º oscillations with 60 s exposures. Of the 20592 reflections that were collected, 7098 were unique (Rint = 0.1071); equivalent reflections were merged. Data were collected and integrated using the Bruker SAINT software package.7 Data were corrected for 225 absorption effects using a multi-scan technique (SADABS)8. The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.9 The final cycle of full-matrix least-squares refinement on F2 was based on 7098 reflections and 378 variable parameters (largest parameter shift was 0.021 times its esd).12  226 6.6 References  1. (a) Yang, J.-S.; Swager, T. M. J. Am. Chem. Soc. 1998, 120, 11864-11873.  (b) Zhu, Z.; Swager, T. M. Org. Lett. 2001, 3, 3471-3474.  (b) Zhao, D.; Swager, T. M. Macromolecules 2005, 38, 9377-9384.  (c) (a) Long, T. M.; Swager, T. M. J. Am. Chem. Soc. 2003, 125, 14113-14119.  (d) Amara, J. P.; Swager, T. M. Macromolecules 2004, 37, 3068-3070.  (e) Tsui, N. T.; Torun, L.; Pate, B. D.; Paraskos, A. J.; Swager, T. M.; Thomas, E. L. Adv. Func. Mater. 2007, 17, 1595- 1602.  (f) Vagin, S.; Ott, A.; Weiss, H.-C.; Karbach, A.; Volkmer, D.; Rieger, B. Eur. J. Inorg. Chem. 2008, 2601-2609.  (g) Ghanem, B. S.; Msayib, K. J.; McKeown, N. B.; Harris, K. D. M.; Pan, Z.; Budd, P. M.; Butler, A.; Selbie, J.; Book, D.; Walton, A. Chem. Commun. 2007, 67-69. 2. (a) Kuboa, T.; Sakamotoa, M.; Kitagawa, H.; Nakasuji, K. Synth. Met. 2005, 153, 465-468.  (b) Konno, Y.; Matsushita, N. Bull. Chem. Soc. Jpn. 2006, 79, 1046-1053. 3. Fu, P. P.; Harvey, R. G. J. Org. Chem. 1977, 42, 2407-2410. 4. Iwata, M.; Emoto, S. Bull. Chem. Soc. Jpn. 1974, 47, 1687-1692. 5. Roy, X.; Thompson, L. K.; Coombs, N.; MacLachlan, M. J. Angew. Chem. Int. Ed. 2008, 47, 511-514. 6. Sheldrick, G. M. Acta Cryst. 2008, A64, 112-122. 7. SAINT. Version 6.02. Bruker AXS Inc., Madison, Wisconsin, USA. 1999. 8. SADABS. Bruker Nonius area detector scaling and absorption correction - V2.05, Bruker AXS Inc., Madison, Wisconsin, USA.  227  9. SIR92. Altomare, A.; Cascarano, M.; Giacovazzo, C.; Guagliardi, A. J. Appl. Cryst. 1994, 26, 343-350. 10. SQUEEZE - van der Sluis, P.; Spek, A. L. Acta Crystallogr., Sect A 1990, 46, 194- 201. 11. PLATON, A Multipurpose Crystallographic Tool, Utrecht University, Utrecht, The Netherlands, Spek, A. L. (1998). 12. Least Squares function minimized:   Σw(Fo2-Fc2)2 13. Crystallographic data were collected through the SCrALS (Service Crystallography at Advanced Light Source) program at the Small-Crystal Crystallography Beamline 11.3.1 (developed by the Experimental Systems Group) at the Advanced Light Source (ALS). The ALS is supported by the U.S. Department of Energy, Office of Energy Sciences Materials Sciences Division, under contract DE-AC02-05CH11231 at Lawrence Berkeley National Laboratory. 14. APEX2. Version 2008.50.0. Bruker Analytical X-ray Instruments, Inc., Madison, Wisconsin, USA. 15. SAINT. Version 7.56A. Bruker Analytical X-ray Instruments, Inc., Madison, Wisconsin, USA. 228 APPENDIX 1 CRYSTALLOGRAPHIC DATA  Table A1.1.  Selected crystallographic data for compound 162. compound 162 formula C22H14O4 MW 342.34 lattice type rhombohedral space group R -3 c a (Å) 12.1852(12) b (Å) 12.185 c (Å) 18.277(2) α (°) 90 β (°) 90 γ (°) 120 V (Å3) 2350.1(4) Z 4 Dcalc (g cm-3) 1.451 T (K) 173(1) GOF on F2 1.075 R1 [I>2σ (I)] 0.0591 wR2 (all data) 0.1844  229 Table A1.2.  Selected crystallographic data for compounds 131-134. compound 131 132 132 • 1.5MeCN 133 134 • MeCN formula C22H14N2 C26H14N6 C29H18.5N7.5 C26H16N2 C42H27N3 MW 306.35 410.43 472.01 356.41 573.67 lattice type triclinic monoclinic monoclinic triclinic triclinic space group P -1 P21/n C2/c P -1 P -1 a (Å) 8.0472(2) 12.0429(10) 30.050(4) 7.9981(18) 10.188(4) b (Å) 8.87180(10) 12.7446(12) 8.5056(8) 8.416(2) 11.488(4) c (Å) 12.4711(8) 12.5790(10) 17.790(3) 15.052(3) 12.960(5) α (°) 74.642(11) 90 90 74.060(14) 83.02(3) β (°) 77.243(11) 96.992(4) 93.173(5) 85.804(14) 76.48(3) γ (°) 61.931(8) 90 90 64.404(10) 83.77(2) V (Å3) 752.72(5) 1916.3(3) 4539.9(10) 877.4(3) 1458.8(9) Z 2 4 8 2 2 Dcalc (g cm-3) 1.352 1.423 1.381 1.349 1.306 T (K) 173(1) 173(1) 173(1) 173(1) 173(1) GOF on F2 1.063 1.007 1.028 1.089 1.051 R1 [I>2σ (I)] 0.0468 0.0760 0.0764 0.1113 0.0882 wR2 (all data) 0.1202 0.1053 0.1071 0.2468 0.2365  230 Table A1.3.  Selected crystallographic data for compounds 184-186. compound 184 185 186 • 1.5MeCN formula C24H17N3Cu2I2 C15H10N4Cu2I2 C33H21N3CuI MW 728.29 627.15 649.99 lattice type monoclinic triclinic monoclinic space group P21/c P -1 C2/c a (Å) 9.1569(11) 9.8372(5) 20.034(3) b (Å) 31.760(4) 11.9700(6) 8.3663(11) c (Å) 8.2462(9) 15.8616(8) 35.981(6) α (°) 90 75.471(2) 90 β (°) 99.380(3) 86.569(2) 98.168(7) γ (°) 90 67.827(2) 90 V (Å3) 2366.1(5) 1673.03(15) 5969.5(16) Z 4 4 8 Dcalc (g cm-3) 2.044 2.490 1.446 T (K) 173(1) 173(1) 173(1) GOF on F2 1.143 0.983 1.167 R1 [I>2σ (I)] 0.0526 0.0260 0.1025 wR2 (all data) 0.1138 0.0635 0.1819  231 Table A1.4.  Selected crystallographic data for compound 197. compound 197 formula C36.5H35.5N3Ni1.5O6.25S2.75 MW 792.41 lattice type triclinic space group P -1 a (Å) 13.2357(19) b (Å) 18.408(3) c (Å) 20.908(4) α (°) 82.027(6) β (°) 80.467(6) γ (°) 74.509(6) V (Å3) 4817.4(14) Z 4 Dcalc (g cm-3) 1.093 T (K) 173(1) GOF on F2 0.944 R1 [I>2σ (I)] 0.0558 wR2 (all data) 0.1554  232 Table A1.5.  Selected crystallographic data for compound 200, 206, 209 and 210. compound 200 206 209 210 formula C44H40N4O2S2Pt C32.5H20N4O0.5 C256H144N32Cl8Cu8  N/A MW 916.01 474.53 4459.95 N/A lattice type monoclinic monoclinic monoclinic monoclinic space group P 21/c P 21/n C 2/c P 21/c a (Å) 11.8563(9) 8.0111(6) 88.779(12) 15.544(3) b (Å) 8.1225(5) 30.610(3) 8.234(1) 27.483(7) c (Å) 23.6634(17) 18.4518(18) 27.418(4) 13.623(4) α (°) 90 90 90 90 β (°) 93.544(3) 97.264(4) 102.62 95.76(1) γ (°) 90 90 90 90 V (Å3) 2274.5(3) 4488.4(7) 19558.7(80) 5790.3(41) Z 2 8 4 4 Dcalc (g cm-3) 1.338 1.404 1.515 N/A T (K) 173(1) 173(1) 150(2) 173(1) GOF on F2 1.084 0.974 1.059 1.342 R1 [I>2σ (I)] 0.0372 0.0531 0.0567 0.1705 wR2 (all data) 0.0987 0.1182 0.1507 0.4820  233 APPENDIX 2 1H AND 13C NMR EXPERIMENTS  Table A2.1.  90° pulse lengths, power levels and delay times used in NMR experiments. Spectrometer Nucleus Pulse length (μs) Power level (dB) Delay time (s) AV-300 1H 11.25 0 1.00 AV-300 13C 9.45 -1 1.00 AV-400 1H 14.00 1 1.00 AV-400 13C 9.50 -3 1.00  For 1H and 13C NMR spectra of 131, 132, 136, 138, 142-145, 150a, 152a, 153a and 154a, see reference: Chong, J.H.; MacLachlan, M. J. Inorg. Chem. 2006, 45, 1442-1444. For 1H and 13C NMR spectra of 133-135, see reference: Chong, J.H.; MacLachlan, M. J. J. Org. Chem. 2007, 72, 8683-8690.  234  Figure A2.1.  1H NMR spectrum (400 MHz, CDCl3) of 148a.  Figure A2.2.  13C NMR spectrum (75.4 MHz, CDCl3) of 148a. 235  Figure A2.3.  1H NMR spectrum (300 MHz, CDCl3) of 148b.  Figure A2.4.  13C NMR spectrum (100.6 MHz, CDCl3) of 148b. 236  Figure A2.5.  1H NMR spectrum (300 MHz, DMSO-d6) of 149a.  Figure A2.6.  13C NMR spectrum (100.6 MHz, DMSO-d6) of 149a. 237  Figure A2.7.  1H NMR spectrum (400 MHz, DMSO-d6) of 149b.  Figure A2.8.  13C NMR spectrum (100.6 MHz, DMSO-d6) of 149b. 238  Figure A2.9.  1H NMR spectrum (400 MHz, DMSO-d6) of 137.  Figure A2.10.  13C NMR spectrum (100.6 MHz, DMSO-d6) of 137. 239  Figure A2.11.  1H NMR spectrum (300 MHz, CDCl3) of 150b.  Figure A2.12.  13C NMR spectrum (75.4 MHz, CDCl3) of 150b. 240  Figure A2.13.  1H NMR spectrum (300 MHz, CDCl3) of 152b.  Figure A2.14.  13C NMR spectrum (100.6 MHz, CDCl3) of 152b. 241  Figure A2.15.  1H NMR spectrum (300 MHz, CDCl3) of 153b.  Figure A2.16.  13C NMR spectrum (100.6 MHz, CDCl3) of 153b. 242  Figure A2.17.  1H NMR spectrum (400 MHz, DMSO-d6) of 154b.  Figure A2.18.  13C NMR spectrum (100.6 MHz, DMSO-d6) of 154b. 243  Figure A2.19.  1H NMR spectrum (400 MHz, CDCl3) of 165.  Figure A2.20.  13C NMR spectrum (100.6 MHz, CDCl3) of 165. 244  Figure A2.21.  1H NMR spectrum (300 MHz, CDCl3) of 168.  Figure A2.22.  13C NMR spectrum (100.6 MHz, CDCl3) of 168. 245  Figure A2.23.  1H NMR spectrum (400 MHz, acetone-d6) of 174.  Figure A2.24.  13C NMR spectrum (100.6 MHz, acetone-d6) of 174. 246  Figure A2.25.  1H NMR spectrum (300 MHz, CDCl3) of 190.  Figure A2.26.  13C NMR spectrum (100.6 MHz, CDCl3) of 190. 247  Figure A2.27.  1H NMR spectrum (400 MHz, DMSO-d6) of 191.  Figure A2.28.  13C NMR spectrum (100.6, DMSO-d6) of 191. 248  Figure A2.29.  1H NMR spectrum (300 MHz, CDCl3) of 192.  Figure A2.30.  13C NMR spectrum (75.4 MHz, CDCl3) of 192. 249  Figure A2.31.  1H NMR spectrum (400 MHz, DMSO-d6) of 193.  Figure A2.32.  1H NMR spectrum (400 MHz, CD2Cl2) of 194. 250  Figure A2.33.  13C NMR spectrum (75.4 MHz, CDCl3) of 194.  Figure A2.34.  1H NMR spectrum (400 MHz, CDCl3) of 195. 251  Figure A2.35.  13C NMR spectrum (100.6 MHz, CDCl3) of 195.  Figure A2.36.  1H NMR spectrum (300 MHz, CDCl3) of 196. 252  Figure A2.37.  13C NMR spectrum (100.6 MHz, CDCl3) of 196.  Figure A2.38.  1H NMR spectrum (400 MHz, DMSO-d6) of 197. 253  Figure A2.39.  13C NMR spectrum (100.6 MHz, DMSO-d6) of 197.  Figure A2.40.  1H NMR spectrum (400 MHz, CD2Cl2) of 198. 254  Figure A2.41.  13C NMR spectrum (100.6 MHz, CD2Cl2) of 198.  Figure A2.42.  13C NMR spectrum from HMQC (100.6 MHz, CDCl3) of 198. 255  Figure A2.43.  1H NMR spectrum (400 MHz, CDCl3) of 199.  Figure A2.44.  13C NMR spectrum (100.6 MHz, CDCl3) of 199. 256  Figure A2.45.  1H NMR spectrum (300 MHz, DMSO-d6) of 200.  Figure A2.46.  1H NMR spectrum (400 MHz, CDCl3) of 206. 257  Figure A2.47.  13C NMR spectrum (100.6 MHz, CDCl3) of 206.  Figure A2.48.  1H NMR spectrum (400 MHz, CD2Cl2) of 207. 258  Figure A2.49.  13C NMR spectrum (100.6 MHz, CDCl3) of 207.  Figure A2.50.  1H NMR spectrum (400 MHz, CDCl3) of 208.

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