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The synthesis of organoiron complexes and coordination polymers containing functionalized terpyridines Pilfold, Jessica Lori 2013

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THE SYNTHESIS OF ORGANOIRON COMPLEXES AND COORDINATION POLYMERS CONTAINING FUNCTIONALIZED TERPYRIDINES by JESSICA LORI PILFOLD  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE COLLEGE OF GRADUATE STUDIES (Chemistry)  THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan)  April 2013 © Jessica Lori Pilfold, 2013  Abstract Organic terpyridine derivatives were prepared via nucleophilic substitution at the 4′position and coordinated with iron, ruthenium, or nickel to form several chelated complexes. These chelated compounds were reacted with chloro-terminated organoiron carboxylic acid complexes to afford terpyridine-based monomers containing three metal centres. A monomer containing a cationic iron complex with two terminal terpyridine moieties was synthesized by employing a Steglich esterification between a dicarboxylic acid organoiron complex and a hexanediol-functionalized terpyridine. The monomers containing multimetal centres were polymerized through nucleophilic aromatic substitution reactions with bisphenol A or hydroquinone, while the monomer containing one organoiron moiety and terminal terpyridine groups was polymerized through chelation to iron or nickel. The thermal properties of the polymers were investigated, with differential scanning calorimetry providing glass transition temperatures of approximately -21 °C for the ironchelated polymers. Thermogravimetric analysis showed stepwise degradation of the cationic iron moieties, followed by the aromatic backbone, with the final decomposition step representing the loss of the bonding interaction between the iron centre and the nitrogen atoms of the chelated terpyridine groups.  ii  Table of Contents Abstract... ............................................................................................................................... ii Table of Contents .................................................................................................................. iii List of Tables ...........................................................................................................................v List of Figures ....................................................................................................................... vi List of Schemes..................................................................................................................... xii List of Symbols, Abbreviations or Other.......................................................................... xiv Acknowledgements ............................................................................................................ xvii Dedication .......................................................................................................................... xviii Chapter 1 Introduction ..........................................................................................................1 1.1  Origins and synthesis of the substituted terpyridine ligand .........................................1  1.2 Terpyridine metal complexes .......................................................................................5 1.3 Macrocycles and polymers containing functionalized terpyridines .............................7 1.4  Organoiron complexes based on cationic cyclopentadienyliron(II) moieties............10  1.5  Cationic organoiron complexes containing carboxylic acid groups ..........................11  1.6 Organoiron-based polymers .......................................................................................13 1.7  Outlook ......................................................................................................................13  Chapter 2 Synthesis and Characterization of 4′-Substituted Terpyridines and Organoiron Terpyridine Complexes .................................................................15 2.1  Synthesis of organic functionalized terpyridines .......................................................15  2.2  Synthesis of organoiron-containing terpyridines .......................................................27  2.3  Synthesis of terpyridine-based metal-chelated complexes ........................................40  2.4  Experimental ..............................................................................................................55  Chapter 3 Synthesis and Characterization of Terpyridine-Based Monomers and Coordination Polymers Containing Cationic Iron Moieties ...........................63  iii  3.1 Synthesis and characterization of cationic iron-containing functionalized terpyridine monomers ................................................................................................63 3.2 Synthesis and characterization of cationic iron-containing terpyridine coordination polymers ...............................................................................................70 3.3  Experimental ..............................................................................................................81  Chapter 4 Conclusion ...........................................................................................................85 References..............................................................................................................................87 Appendices ............................................................................................................................97 Appendix A: Spectral data for chapter 2 ...........................................................................97 A.1 NMR spectra ..............................................................................................................97 A.2 FTIR-ATR spectra ...................................................................................................120 A.3 UV-visible spectra....................................................................................................124 A.4 MALDI-TOF mass spectra ......................................................................................125 Appendix B: Spectral data for chapter 3..........................................................................126 B.1 NMR spectra ............................................................................................................126 B.2 FTIR-ATR spectra....................................................................................................136 B.3 UV-visible spectra ....................................................................................................139 B.4 MALDI-TOF mass spectra.......................................................................................142  iv  List of Tables Table 2.1  Summary of 1H and 13C NMR chemical shifts for complexes 2.16 and 2.17. ................................................................................................................... 53  Table 3.1  Summary of TGA results of iron-containing polymers 3.3, 3.6a, and 3.6b. ................................................................................................................... 78  v  List of Figures Figure 1.1  The 2,2′:6′,2″-terpyridine molecule.................................................................... 1  Figure 1.2  Octahedral metal complex of 4′-substituted terpyridine. ................................... 5  Figure 1.3  Charge-transfer state consisting of a Ni(II)-alkyl cation and a reduced ligand. ................................................................................................................. 7  Figure 1.4  Dendritic cores containing multiple terpyridine metal-binding domains.70 ....... 8  Figure 1.5  Ruthenium(II) coordination polymer prepared by Rehahn.78 ............................ 9  Figure 1.6  Ditopic terpyridine ligands containing oligomeric and polymeric spacers.79–82 ........................................................................................................ 9  Figure 2.1  1  H NMR spectra of tpy-Cl 2.3 (top) and hexanediol terpyridine 2.4  (bottom). ........................................................................................................... 17 Figure 2.2  13  C NMR spectra of tpy 2.3 (top) and hexanediol terpyridine 2.4  (bottom). ........................................................................................................... 19 Figure 2.3  Resonance structure of ether-substituted terpyridine. ...................................... 20  Figure 2.4  IR spectrum of hexanediol terpyridine 2.4. ...................................................... 21  Figure 2.5  (a) 1H NMR spectrum and (b) 13C NMR spectrum of hydroxybenzyl alcohol tpy 2.5. ................................................................................................. 23  Figure 2.6  Portion of 13C NMR spectrum of acid terpyridine 2.6, showing the aromatic carbon signals of the 4-mercaptobenzoic acid moiety. ..................... 25  Figure 2.7  Comparison of UV-visible spectra of hexanediol terpyridine 2.4 (red) and acid terpyridine 2.6 (blue) in the region of 220-480 nm. .......................... 26  Figure 2.8  gHSQC NMR spectrum of acid complex 2.8. .................................................. 29  Figure 2.9  Aromatic region of the gHMBC NMR spectrum of diacid complex 2.9. ........ 31  Figure 2.10  IR spectrum of diacid complex 2.9. ................................................................. 32  Figure 2.11  (a) gHSQC spectrum displaying the 3JCH correlation of Ha and Hb to Ca and Cb in complex 2.11; (b) gHMBC spectrum of complex 2.11 showing the 3JCH correlation of Ha and Hb to Cc and Cd, respectively. .......................... 34 vi  Figure 2.12  1  Figure 2.13  gHSQC spectrum of complex 2.12 displaying the 3JCH correlation of Ha  H NMR spectrum of complex 2.12. ................................................................ 36  and Hb to Ca and Cb. ......................................................................................... 37 Figure 2.14  Comparison of UV-visible spectra of complex 2.11 (red) and complex 2.12 (blue) in the region of 220-480 nm. ......................................................... 39  Figure 2.15  1  Figure 2.16  Comparison of the 13C NMR spectra for hexanediol tpy 2.4 (top) and its  H NMR spectrum of iron-chelated complex 2.13........................................... 41  iron-chelated complex 2.13 (bottom). .............................................................. 43 Figure 2.17  UV-visible spectrum of iron(II)-chelated complex 2.13. ................................. 44  Figure 2.18  Mass spectrum of complex 2.14, showing the molecular ion peak [M+PF6]+ at m/z 901.24.................................................................................... 46  Figure 2.19  UV-visible spectrum of nickel(II)-chelated complex 2.14.............................. 47  Figure 2.20  1  Figure 2.21  Portions of the mass spectrum of complex 2.15. ............................................. 50  Figure 2.22  UV-visible spectra of complexes 2.16 (red) and 2.17 (blue). .......................... 55  Figure 3.1  1  Figure 3.2  Portion of the gCOSY NMR spectrum of monomer 3.1 showing the 1JHH  H NMR spectrum of complex 2.15. ................................................................ 49  H NMR spectrum of monomer 3.1. ................................................................ 65  correlation between Hm and Hn. ....................................................................... 66 Figure 3.3  Mass spectrum of monomer 3.1, showing the molecular ion peak [MPF6]+ at m/z 1891.10. ........................................................................................ 67  Figure 3.4  Mass spectrum of monomer 3.2, showing the molecular ion peak [M2PF6]+ at m/z 1748.19. ...................................................................................... 68  Figure 3.5  Comparison of UV-vis spectra of complex 2.13 (red) and monomer 3.1 (blue). ............................................................................................................... 69  Figure 3.6  Portion of the gCOSY NMR spectrum of polymer 3.3, showing the 1JHH correlation between He and Hf, and Hf and Hg. ................................................ 71  vii  Figure 3.7  Portion of the gHSQC spectrum of polymer 3.3 showing the 1JCH correlation between carbons Ce and Ch to protons He and Hh, respectively. ..................................................................................................... 72  Figure 3.8  Comparison of IR spectra of complex 2.14 (red) and polymer 3.4 (blue) in the region of 600-2000 cm-1. ........................................................................ 74  Figure 3.9  1  Figure 3.10  TGA of polymer 3.3. ........................................................................................ 79  Figure 3.11  DSC curve of polymer 3.3 (Tg = -21.17 °C). ................................................... 80  Figure A.1.1  1  Figure A.1.2  gCOSY NMR spectrum of hydroxybenzyl alcohol tpy 2.5 (400 MHz,  H NMR spectrum of polymer 3.6b. ................................................................ 77  H NMR spectrum of hexanediol tpy 2.4 (400 MHz, DMSO-d6). ................... 97  DMSO-d6). ....................................................................................................... 98 Figure A.1.3  gHSQC NMR spectrum of hydroxybenzyl alcohol tpy 2.5 (400 MHz, DMSO-d6). ....................................................................................................... 98  Figure A.1.4  gHMBC NMR spectrum of hydroxybenzyl alcohol tpy 2.5 (400 MHz, DMSO-d6). ....................................................................................................... 99  Figure A.1.5  1  Figure A.1.6  13  Figure A.1.7  gCOSY NMR spectrum of acid tpy 2.6 (400 MHz, DMSO-d6). ................... 100  Figure A.1.8  gHSQC NMR spectrum of acid tpy 2.6 (400 MHz, DMSO-d6). ................... 101  Figure A.1.9  gHMBC NMR spectrum of acid tpy 2.6 (400 MHz, DMSO-d6). .................. 101  H NMR spectrum of acid tpy 2.6 (400 MHz, DMSO-d6). .............................. 99 C NMR spectrum of acid tpy 2.6 (100 MHz, DMSO-d6)............................ 100  Figure A.1.10 1H NMR spectrum of acid complex 2.8 (400 MHz, acetone-d6). .................. 102 Figure A.1.11  13  C NMR spectrum of acid complex 2.8 (100 MHz, acetone-d6). ................. 102  Figure A.1.12 gHSQC NMR spectrum of acid complex 2.8 (400 MHz, acetone-d6). .......... 103 Figure A.1.13 gHMBC NMR spectrum of acid complex 2.8 (400 MHz, acetone-d6). ......... 103 Figure A.1.14 1H NMR spectrum of diacid complex 2.9 (400 MHz, acetone-d6). ............... 104 Figure A.1.15  13  C NMR spectrum of diacid complex 2.9 (100 MHz, acetone-d6). .............. 104  Figure A.1.16 gHSQC NMR spectrum of diacid complex 2.9 (400 MHz, acetone-d6). ....... 105 viii  Figure A.1.17 gHMBC NMR spectrum of diacid complex 2.9 (400 MHz, acetone-d6). ...... 105 Figure A.1.18 1H NMR spectrum of complex 2.11 (400 MHz, DMSO-d6). ......................... 106 Figure A.1.19  13  C NMR spectrum of complex 2.11 (100 MHz, DMSO-d6)......................... 106  Figure A.1.20 gCOSY NMR spectrum of complex 2.11 (400 MHz, DMSO-d6). ................ 107 Figure A.1.21 gHSQC NMR spectrum of complex 2.11 (400 MHz, DMSO-d6). ................ 107 Figure A.1.22 gHMBC NMR spectrum of complex 2.11 (400 MHz, DMSO-d6). ............... 108 Figure A.1.23  13  C NMR spectrum of complex 2.12 (100 MHz, DMSO-d6)......................... 108  Figure A.1.24 gCOSY NMR spectrum of complex 2.12 (400 MHz, DMSO-d6). ................ 109 Figure A.1.25 gHSQC NMR spectrum of complex 2.12 (400 MHz, DMSO-d6). ................ 109 Figure A.1.26 gHMBC NMR spectrum of complex 2.12 (400 MHz, DMSO-d6). ............... 110 Figure A.1.27  13  C NMR spectrum of complex 2.13 (100 MHz, DMSO-d6)......................... 110  Figure A.1.28 gCOSY NMR spectrum of complex 2.13 (400 MHz, DMSO-d6). ................ 111 Figure A.1.29 gHSQC NMR spectrum of complex 2.13 (400 MHz, DMSO-d6). ................ 111 Figure A.1.30 gHMBC NMR spectrum of complex 2.13 (400 MHz, DMSO-d6). ............... 112 Figure A.1.31  13  C NMR spectrum of complex 2.15 (100 MHz, DMSO-d6)......................... 112  Figure A.1.32 gCOSY NMR spectrum of complex 2.15 (400 MHz, DMSO-d6). ................ 113 Figure A.1.33 gHSQC NMR spectrum of complex 2.15 (400 MHz, DMSO-d6). ................ 113 Figure A.1.34 gHMBC NMR spectrum of complex 2.15 (400 MHz, DMSO-d6). ............... 114 Figure A.1.35 1H NMR spectrum of complex 2.16 (400 MHz, DMSO-d6). ......................... 114 Figure A.1.36  13  C NMR spectrum of complex 2.16 (100 MHz, DMSO-d6)......................... 115  Figure A.1.37 gCOSY NMR spectrum of complex 2.16 (400 MHz, DMSO-d6). ................ 115 Figure A.1.38 gHSQC NMR spectrum of complex 2.16 (400 MHz, DMSO-d6). ................ 116 Figure A.1.39 gHMBC NMR spectrum of complex 2.16 (400 MHz, DMSO-d6). ............... 116 Figure A.1.40 1H NMR spectrum of complex 2.17 (400 MHz, DMSO-d6). ......................... 117 Figure A.1.41  13  C NMR spectrum of complex 2.17 (100 MHz, DMSO-d6)......................... 117  ix  Figure A.1.42 gCOSY NMR spectrum of complex 2.17 (400 MHz, DMSO-d6). ................ 118 Figure A.1.43 gHSQC NMR spectrum of complex 2.17 (400 MHz, DMSO-d6). ................ 118 Figure A.1.44 gHMBC NMR spectrum of complex 2.17 (400 MHz, DMSO-d6). ............... 119 Figure A.2.1 FTIR-ATR spectrum of acid tpy. 2.6. ............................................................ 120 Figure A.2.2  FTIR-ATR spectrum of complex 2.11. .......................................................... 120  Figure A.2.3  FTIR-ATR spectrum of complex 2.12. .......................................................... 121  Figure A.2.4  FTIR-ATR spectrum of complex 2.13. .......................................................... 121  Figure A.2.5  FTIR-ATR spectrum of complex 2.14. .......................................................... 122  Figure A.2.6  FTIR-ATR spectrum of complex 2.15. .......................................................... 122  Figure A.2.7  FTIR-ATR spectrum of complex 2.16. .......................................................... 123  Figure A.2.8  FTIR-ATR spectrum of complex 2.17. .......................................................... 123  Figure A.3.1  UV-visible spectrum of complex 2.9 (in CH3CN). ........................................ 124  Figure A.3.2  UV-visible spectrum of complex 2.15 (in CH3CN). ...................................... 124  Figure A.4.1  MALDI-TOF mass spectrum of complex 2.15. ............................................. 125  Figure B.1.1  13  Figure B.1.2  gCOSY NMR spectrum of monomer 3.1 (400 MHz, acetone-d6). ................ 127  Figure B.1.3  gHSQC NMR spectrum of monomer 3.1 (400 MHz, acetone-d6). ................ 127  Figure B.1.4  gHMBC NMR spectrum of monomer 3.1 (400 MHz, acetone-d6). ............... 128  Figure B.1.5  1  Figure B.1.6  13  Figure B.1.7  gCOSY NMR spectrum of polymer 3.3 (400 MHz, DMSO-d6). ................... 130  Figure B.1.8  gHSQC NMR spectrum of polymer 3.3 (400 MHz, DMSO-d6). ................... 130  Figure B.1.9  gHMBC NMR spectrum of polymer 3.3 (400 MHz, DMSO-d6). .................. 131  C NMR spectrum of monomer 3.1 (100 MHz, acetone-d6)......................... 126  H NMR spectrum of polymer 3.3 (400 MHz, DMSO-d6). ........................... 129 C NMR spectrum of polymer 3.3 (100 MHz, DMSO-d6). .......................... 129  Figure B.1.10 1H NMR spectrum of polymer 3.6a (400 MHz, DMSO-d6)........................... 132 Figure B.1.11 gCOSY NMR spectrum of polymer 3.6a (400 NMR, DMSO-d6). ................ 132  x  Figure B.1.12 gHSQC NMR spectrum of polymer 3.6a (400 MHz, DMSO-d6). ................. 133 Figure B.1.13  13  C NMR spectrum of polymer 3.6b (100 MHz, DMSO-d6). ........................ 134  Figure B.1.14 gCOSY NMR spectrum of polymer 3.6b (400 MHz, DMSO-d6). ................. 134 Figure B.1.15 gHSQC NMR spectrum of polymer 3.6b (400 MHz, DMSO-d6). ................. 135 Figure B.2.1  FTIR-ATR spectrum of monomer 3.1. ........................................................... 136  Figure B.2.2  FTIR-ATR spectrum of monomer 3.2. ........................................................... 136  Figure B.2.3  FTIR-ATR spectrum of polymer 3.3. ............................................................. 137  Figure B.2.4  FTIR-ATR spectrum of polymer 3.6a. ........................................................... 137  Figure B.2.5  FTIR-ATR spectrum of polymer 3.6b. ........................................................... 138  Figure B.3.1  UV-visible spectrum of monomer 3.1 (in CH3CN). ....................................... 139  Figure B.3.2  UV-visible spectrum of monomer 3.2 (in CH3CN). ....................................... 139  Figure B.3.3  UV-visible spectrum of polymer 3.3 (in CH3CN). ......................................... 140  Figure B.3.4  UV-visible spectrum of polymer 3.4 (in CH3CN). ......................................... 140  Figure B.3.5  UV-visible NMR spectrum of polymer 3.6a (in CH3CN). ............................. 141  Figure B.3.6  UV-visible spectrum of polymer 3.6b (in CH3CN). ....................................... 141  Figure B.4.1  MALDI-TOF mass spectrum of monomer 3.1. .............................................. 142  Figure B.4.2  MALDI-TOF mass spectrum of monomer 3.2. .............................................. 143  xi  List of Schemes Scheme 1.1  The Kröhnke synthesis for 4′-(o-toluyl)terpyridine. .......................................... 2  Scheme 1.2  Synthesis of 4′-chloroterpyridine by Constable and coworkers.19 ..................... 3  Scheme 1.3  Synthetic routes to 4′-substituted terpyridines using primary alcohols. ............ 4  Scheme 1.4  Synthesis of chloroarene-coordinated cyclopentadienyliron complexes via ligand exchange. ......................................................................................... 11  Scheme 1.5  Synthesis of monometallic acid complex containing a cationic iron moiety............................................................................................................... 12  Scheme 1.6  Synthesis of bimetallic acid complex containing two cationic iron moieties. ........................................................................................................... 12  Scheme 1.7  Synthesis of organoiron polymers via nucleophilic aromatic substitution. ..... 13  Scheme 2.1  Synthesis of trione 2.1, tpy-OH 2.2, and tpy-Cl 2.3. ....................................... 15  Scheme 2.2  Synthesis of hexanediol terpyridine 2.4. .......................................................... 16  Scheme 2.3  Synthesis of 4-hydroxybenzyl alcohol terpyridine 2.5. ................................... 21  Scheme 2.4  Synthesis of acid terpyridine 2.6 ...................................................................... 24  Scheme 2.5  Synthesis of acid complex 2.8.......................................................................... 28  Scheme 2.6  Synthesis of diacid complex 2.9. ..................................................................... 30  Scheme 2.7  Synthesis of organoiron-containing terpyridine 2.11....................................... 33  Scheme 2.8  Synthesis of organoiron-containing terpyridine 2.12....................................... 35  Scheme 2.9  Synthesis of [Fe(hex-typ)2][PF6]2 (complex 2.13). .......................................... 40  Scheme 2.10  Synthesis of [Ni(hex-tpy)][PF6]2 (complex 2.14). ........................................... 45  Scheme 2.11  Synthesis of [Ru(hex-tpy)2][PF6]2 (complex 2.15). ......................................... 48  Scheme 2.12  Synthesis of iron-chelated complexes 2.16 (where R = hydroxybenzyl alcohol) and 2.17 (where R = 4-mercaptobenzoic acid). ................................. 52  Scheme 3.1  Synthesis of monomers 3.1 and 3.2. ................................................................ 64  Scheme 3.2  Synthesis of iron(II) coordination polymer 3.3. ............................................... 70 xii  Scheme 3.3  Synthesis of coordination polymer 3.4 containing nickel(II). ......................... 73  Scheme 3.4  Synthesis of Fe(II) coordination polymers 3.6a (bisphenol A spacer) and 3.6b (hydroquinone spacer).............................................................................. 75  xiii  List of Symbols, Abbreviations or Other The following is a list of abbreviations and symbols employed in this thesis, most of which are in common use in the chemical literature. °C  degrees Celsius  δ  chemical shift  br  broad  cm-1  wavenumbers (in infrared spectroscopy)  13  carbon-13 nuclear magnetic resonance spectroscopy  C NMR  conc.  concentrated  Cp  cyclopentadienyl (C5H5)  d  doublet  dd  doublet of doublets  ddd  doublet of doublet of doublets  dt  doublet of triplets  d6  containing 6 deuterium atoms  DCC  N,N’-dicyclohexylcarbodiimide  DCM  dichloromethane, CH2Cl2  DCU  N,N’-dicyclohexylurea  DMAP  N,N’-4-dimethylaminopyridine  DME  1,2-dimethoxyethane  DMF  N,N-dimethylformamide  DMSO  dimethylsulfoxide  DSC  differential scanning calorimetry  eq.  equivalents xiv  Et  ethyl  g  gram  gCOSY  gradient correlation spectroscopy  GPC  gel permeation chromatography  h  hours  1  proton nuclear magnetic resonance spectroscopy  H NMR  hex-tpy  hexanediol terpyridine  HMBC  heteronuclear multiple bond coherence spectroscopy  HSQC  heteronuclear single quantum coherence  Hz  Hertz  IR  infrared spectroscopy  J  coupling constant (Hz)  L  litre  M  molar  m  multiplet  MALDI  matrix-assisted laser desorption ionization  Me  methyl  MHz  megahertz  min  minutes  mL  millilitre  MLCT  metal-to-ligand charge transfer  mmol  millimole  mol  mole  pent  pentet xv  ppm  parts per million  q  quartet  RT  room temperature  s  singlet  SNAr  nucleophilic aromatic addition-elimination  t  triplet  td  triplet of doublets  Tg  glass transition temperature  TGA  thermogravimetric analysis  THF  tetrahydrofuran  TOF  time-of-flight  tpy  terpyridine  UV-vis  ultraviolet visible  xvi  Acknowledgements I owe my deepest gratitude to my supervisor, Dr. Alaa Abd-El-Aziz, for his wisdom, patience, and inspiration. His enthusiasm and support made this research possible, and I cannot speak highly enough of him. It has been a privilege to be a member of the Abd-ElAziz research group, and many thanks go to all of its members, both past and present. Special recognition goes to Dr. Patrick Shipman, who mentored me through my undergraduate research; his knowledge, humour, and guidance were always appreciated. Thank you to Michael Cowper, for his contributions towards the terpyridine project and the TGA/DSC/NMR work. A huge thank you goes to Elizabeth Strohm; thanks for sharing the load and being the best officemate a girl could ask for. I am indebted to nearly every member of the third-floor Fipke hallway in some way. To Dr. Kevin Smith, Dr. Steve McNeil, and the current and former members of their research groups: thank you for your assistance and wise words. Thank you to Dr. Paul Shipley, Dr. David Jack, Dr. Edward Neeland, and Dr. Susan Murch for their knowledge and advice. Also, Dr. Jim Bailey and Dr. Sandra Mecklenburg have always been so helpful in countless ways. The camaraderie and conversation I have shared with the faculty and staff of the Department of Chemistry at UBC Okanagan is greatly appreciated and will be remembered. Thank you to my parents for their endless support, understanding, and encouragement. To my friends, words cannot express my love and gratitude; I have enjoyed my time in Kelowna purely because of such amazing people. Finally, thank you to the many students that I have had the pleasure of teaching. Being a TA during my master’s degree has brought more joy to my life than I could have expected, and I am grateful for the friendships I have formed as a result.  xvii  Dedication  To Judit Moldovan, for your friendship, kindness, and sense of humour; you are missed.  xviii  Chapter 1 Introduction 1.1 Origins and synthesis of the substituted terpyridine ligand The 2,2′:6′,2″-terpyridine ligand, herein referred to as ‘terpyridine’ or ‘terpy’, was first synthesized in 1932 by Morgan and Burstall by the oxidative coupling of pyridine using anhydrous ferric chloride as a catalyst.1 The terpyridine product was an accident, as the intent of the reaction was the synthesis of large amounts of 2,2′-bipyridine by scaling up a previously published procedure.2 Due to the large scale of the reaction, side products such as terpyridine were present in quantities great enough to isolate and characterize. Advancement in terpyridine research was slow initially due to its difficult synthesis, though early research in the 1940s described the detection of chelated terpyridine complexes of iron and cobalt.3,4 These reports foreshadowed the utility of the terpyridine moiety in many areas, such as supramolecular chemistry, metal-organic frameworks, and coordination polymers, as a result of its ease of chelation to various metal centres. The terpyridine molecule contains three coupled pyridine rings; its conventional numbering system is shown in Figure 1.1. Terpyridine acts as a tridentate ligand, as the rigid planar geometry forces the molecule to bind to a central octahedral metal ion through the three nitrogen atoms in a meridional manner.  4' 3' 3 4 5 6  5'  2 2' 2" N 6' 1' N1 1" N  3" 4" 5" 6"  Figure 1.1 The 2,2′:6′,2″-terpyridine molecule.  1  Terpyridines are often synthesized by two common synthetic routes: cross-coupling or ring-assembly. The Stille cross-coupling reaction is a palladium-catalyzed carbon-carbon bond generation from the reaction of organotin reagents.5 The mechanism of the reaction is still under debate, and this particular method is less favoured for the synthesis of terpyridines due to its relatively poor conversions.6,7 Schubert and Eschbaumer recently reported the formation of 5,5″-dimethylterpyridine with a yield of 68% using the Stille cross-coupling method, demonstrating greater efficiency than most previous cross-coupling reactions for terpyridine synthesis.8 However, organotin compounds are volatile and toxic, further popularizing the synthetic route of ring-assembly, or ring-closure. The Kröhnke ring-closure synthesis9 is well-known and widely used, facilitated by ammonia condensation with the appropriate enone or a 1,5-diketone; an example of a Kröhnke synthesis of 4′-(o-tolyl)terpyridine is shown in Scheme 1.1.10–14  H  O N  O +  H  O  NaOH  N  EtOH, 0 °C + O  N  I H + I 2  pyridine 80 °C, 4 h  N  N O EtOH reflux  NH3 (aq) N N  N  O N  O N  Scheme 1.1 The Kröhnke synthesis for 4′-(o-toluyl)terpyridine. 2  Sasaki and coworkers have reported yields of up to 85% from some Kröhnke-style condensation reactions to produce terpyridines.15 Wang and Hanan described a facile one-pot synthesis of 4′-arylterpyridines using this method, while Cave et al. have studied solvent-free alternatives to the Kröhnke method to develop a “greener” synthesis.16–18 Substitution of the terpyridine ligand is one of its most desirable features, allowing for the modification of the properties of both the ligand itself and its metal complexes. Perhaps the most utilized ligand is 4′-chloroterpyridine (tpy-Cl) due to its ease of substitution. In 1990, Constable and Ward reported the first synthesis of this ligand with the purpose of homocoupling tpy-Cl to form a bisterpyridine ligand (Scheme 1.2).19  O +  O  O  reflux, 6 h  N  O  NaH, DME  O  O  N  N NH4OAc/EtOH reflux, 6 h  Cl  OH PCl5, POCl3 reflux, 6 h  N N  N  N N  N  Scheme 1.2 Synthesis of 4′-chloroterpyridine by Constable and coworkers.19 With this discovery, functionalized terpyridines became much easier to synthesize by using a SNAr nucleophilic attack on the 4′-position of tpy-Cl. Many ether-functionalized terpyridines soon followed, employing alcohols bearing a variety of functional groups, such as alkyl chains,20–22 amines,21,23–27 thiols,28,29 and carboxylic acids.24,30–33 While using deprotonated alcohols and thiols is the most common route of functionalizing tpy-Cl, amines can also attack the 4′-position of the ligand, resulting in an amino bridge instead of an ether 3  linkage.34–37 However, using an amine as a nucleophile requires high reaction temperatures and the addition of metal salts to withdraw electrons from the 4′-position through complexation to make the reaction more favourable. These metal salts must then be removed from the ligand with KOH or another strong base, causing reaction workup to be very intolerant to certain functional groups, and therefore less desirable than the alcohol-based substitution reactions. In addition to chelation, terpyridine can undergo electrophilic aromatic substitution on any of its pyridyl rings. These substituents are usually part of the precursors used to synthesize the terpyridine molecule. While both symmetrical and asymmetrical substitution on carbons 3-6 and 3″-6″ has been reported, the most common location for substitution is the 4′-position, where the substituent is directed away from the coordination site of the ligand. There are two main synthetic pathways for adding substituents to the 4′-position (Scheme 1.3).  OR OH  route A PCl5, POCl3 ROH  N N  N  N N  N OR  route B ROH PPh3, DIAD  N N  N  Scheme 1.3 Synthetic routes to 4′-substituted terpyridines using primary alcohols. Route A shows nucleophilic aromatic substitution of 4′-chloroterpyridine (tpy-Cl) by primary alcohols, while route B demonstrates SN2-type nucleophilic substitution of 4′-  4  hydroxyterpyridine (tpy-OH) using the same nucleophiles but different conditions.38 The functionalized terpyridines in this thesis were prepared using route A.  1.2 Terpyridine metal complexes Substituted terpyridine ligands are widely used as building blocks in supramolecular chemistry due to their ability to readily coordinate to a variety of transition metal ions. Upon coordination to an octahedral metal centre, terpyridines functionalized at the 4′-position produce a rigid linear moiety, which can be used in the formation of molecular wires and rods.39–44 Figure 1.2 illustrates how two terpyridine moieties orient themselves around a metal centre to create an octahedral complex.  N X  N Mn+ N  N N  Y  N  Figure 1.2 Octahedral metal complex of 4′-substituted terpyridine. Making such octahedral complexes avoids the formation of isomers that occurs when reacting metal ions with bidentate 2,2′-bipyridine, which can cause difficulty in purifying and characterizing the intended product.45 Bipyridine is a ligand of great interest when bonded to transition metals due to the resulting photophysical properties of the metal complexes.46–51 These same properties can be found in metal-chelated terpyridine complexes and are greatly affected by the substituents of the terpyridyl moiety, hence the investigation into functionalized terpyridine metal complexes. Constable and Housecroft reported a variety of terpyridine ligands with diverse functional groups at the 4′-position, including ferrocene,52 5  anthracene,53 thienyl groups,54,55 fluoro-substituted aryl groups,56,57 and C60-functionalized alkyl chains.58 Varying the functional group alters the photophysical properties of the resulting terpyridine-based metal complexes due to the electron-withdrawing or electrondonating capabilities of the atom bonded to the 4′-position.59,60 Iron(II) and ruthenium(II) are perhaps the most common metal ions utilized in the synthesis of coordination polymers containing terpyridines. Not only do they both have the electron configuration d6, but in the case of ruthenium(II), the complexes are always diamagnetic in a low spin electron configuration. Iron(II) complexes can be either low or high spin, depending on the position of the ligands in the spectrochemical series.61 Iron complexes containing two chelated terpyridine groups usually have low spin electron configurations due to a large crystal field splitting caused by the strong field terpyridine moieties. This electronic arrangement accounts for the ability to analyze Fe(II)- and Ru(II)-terpyridine complexes by nuclear magnetic resonance (NMR), as these complexes are diamagnetic. Meanwhile, most monoterpyridine iron complexes, (tpy)FeX2, are high spin.62 Nickel(II) complexes with bisterpyridine ligands are often paramagnetic, making characterization by traditional diamagnetic NMR difficult. However, monoterpyridine nickel complexes are very interesting due to their involvement in cross-coupling of alkyl halides with alkyl nucleophiles.63 Vicic and coworkers noted the stabilizing effect one terpyridyl ligand exhibited on monoalkyl complexes of nickel, confirming the alkyl halide reduction is primarily ligand-based with a transfer of a single electron to the terpyridine ring system (Figure 1.3).64,65  6  N N  Ni  N  CH3 Figure 1.3 ligand.  Charge-transfer state consisting of a Ni(II)-alkyl cation and a reduced  1.3 Macrocycles and polymers containing functionalized terpyridines Ligands with two or more terminal terpyridine moieties linked by a spacer can bind to metals to form rod-like complexes or cyclize to form macrocycles or polymers, depending on the rigidity of the spacer. Normally, a spacer has two primary roles: to control the supramolecular structure, including the intramolecular distances and angles, and to control the electronic communication between components through electron transfer or bond energy. Housecroft and coworkers have reported several iron(II)-directed macrocycles containing terpyridine ligands with ring-like66,67 or box-like68 structures and multiple metal centres. Newkome described the self-assembly of hexagonal macrocyclic complexes where each ligand contains two terpyridine metal-binding domains, using either ruthenium or iron as the complexing metal ion.69 Constable first demonstrated the use of terpyridines to create dendritic cores by synthesizing ligands containing three, four, five, or six terminal terpyridine moieties, allowing for the chelation of various metal ions to form metallodendrimers (Figure 1.4).70  7  N  N  N N  N  N  N  N N  N  N  N  N  N  O  O  O  O  N N  N  N  N  N  N  N  N  N  N  N  N  O  N  O O  N  O O O  N  N  N  N  O O  N N  N  O  N N N  N  N  O  O  N  O  N N  N  O  N  N  N  N N  N  N  N  N N  N  N  Figure 1.4 Dendritic cores containing multiple terpyridine metal-binding domains.70 The terpyridine ligand is ideally suited for the preparation of coordination polymers.71– 75  Colbran76 and Chan77 prepared a series of ditopic terpyridine ligands based on amide- and  imide-linked 4′-p-aminophenylterpyridines. The iron(II) coordination polymers of these ligands were characterized by NMR end-group analysis to find an average polymer length of 17 units, while the ruthenium(II) compounds were employed in light-emitting diodes. Rehahn and coworkers synthesized a soluble ruthenium(II)-containing terpyridine polymer (Figure 1.5) applying two methods: the metal complexation polymerization of an activated Ru(II) species with the bisterpyridine ligand, and the polymerization via the synthesis of the ligand by metal-catalyzed aryl-aryl coupling of the previously formed Ru(tpy)2 units.78 This second 8  method produced only oligomers, while the coordination polymerization resulted in a polymeric material with length >30 units.  N  N N Ru2+  N N  N n  Figure 1.5 Ruthenium(II) coordination polymer prepared by Rehahn.78 Terpyridine ligands bearing flexible oligomeric and polymeric spacers have been reported by Schubert and coworkers (Figure 1.6).79–82 The resulting coordination polymers can be tuned to have specific properties through variation of the metal ion used for complexation and the composition and length of the spacer unit, acting as excellent building blocks for use in supramolecular chemistry.83  N  N N  O  O  O  N  N  N N  O  O  O  N  179  N  N  N  N  Figure 1.6 Ditopic terpyridine ligands containing oligomeric and polymeric spacers.79–82 Terpyridine-based coordination polymers with photophysical and electrochemical properties have been prepared by altering the spacer between two terminal terpyridine units to include a fluorescent or electroactive functional group. Meijer et al. synthesized an iron(II) coordination polymer containing electroactive oligo-p-phenylenevinylene (OPV) functional units, as confirmed by UV-visible spectroscopy.84 A series of ditopic electro- and photoactive 9  terpyridine ligands and their corresponding Zn(II) coordination polymers were recently reported by Che and coworkers.85 The fluorescence properties of the ligand were retained upon complexation of Zn2+, and the polymers were successfully implemented in lightemitting diodes. While gel permeation chromatography (GPC) is often employed to determine the weight and uniformity of polymeric materials, standard GPC analysis on polymers containing terpyridine-metal complexes is rather difficult due to the interaction of the charged compounds with the GPC column material.86,87 While some researchers have successfully analyzed terpyridine-based coordination polymers with GPC,88–90 often these results are only reproducible on frequently used GPC columns rather than new columns. This could be an effect of successful blocking of active sites on the columns over prolonged periods of time caused by the analysis of thousands of samples. However, these results are not to be completely discredited, as separation still takes place on the basis of size exclusion.91  1.4 Organoiron complexes based on cationic cyclopentadienyliron(II) moieties Arene-coordinated organoiron complexes have been extensively studied, largely due to their unique properties and applications in organic and organometallic synthesis, as well as materials chemistry.92–96 To synthesize these compounds, a ligand exchange reaction is performed that exchanges one of the cyclopentadienyl (Cp) rings of ferrocene with an arene, resulting in a cationic η6-haloarene-η5-cyclopentadienyliron complex. In 1963, Nesmeyanov et al. reported the first such exchange reaction between ferrocene and various arenes in the presence of AlCl3 and aluminum.97,98 This method remains the primary synthetic pathway to  10  arene-coordinated cationic iron complexes, and has been adopted for haloarenes, such as 1,4dichlorobenzene (Scheme 1.4).  Fe + Cl  Cl  AlCl3, Al  Cl  Cl Fe+  Scheme 1.4 Synthesis of chloroarene-coordinated cyclopentadienyliron complexes via ligand exchange. The incorporation of cationic η6-chloroarene-η5-cyclopentadienyliron moieties into a molecule can increase solubility, while the coordination of the cationic cyclopentadienyliron moiety to a dihaloarene in particular causes the arene to be much more susceptible to nucleophilic aromatic substitution and addition due to the electron-withdrawing nature of the iron centre.94–96,99–103 These cationic organoiron complexes are activated to the point that substitution of the chloro group by phenolic groups takes place at room temperature using a weak base, such as K2CO3. Such reactions usually require much harsher conditions, including long reaction times or high temperature and pressure.96,99,104 Therefore, cationic cyclopentadienyliron complexes have aided greatly in facilitating more efficient nucleophilic substitution reactions of aromatic systems and the isolation of their reaction products.  1.5 Cationic organoiron complexes containing carboxylic acid groups In the last decade, the Abd-El-Aziz group has utilized the advantageous attributes of the Cp-iron moiety in the synthesis of many organoiron-containing monomers, dendrimers, and polymers.105–112 In this thesis, two carboxylic acid-containing cationic organoiron complexes previously reported by Abd-El-Aziz and coworkers will be employed in  11  esterification reactions for the formation of novel terpyridine-based monomers. The monometallic acid complex is prepared by the reaction of η6-dichlorobenzene-η5cyclopentadienyliron hexafluorophosphate with 4-hydroxybenzoic acid (Scheme 1.5).112 Cl  O  O  Cl  OH  Fe+PF6-  K2CO3  Cl  O OH  Fe+PF6-  DMF, r.t.  HO  Scheme 1.5 Synthesis of monometallic acid complex containing a cationic iron moiety. A similar reaction can be performed with η6-dichlorobenzene-η5-cyclopentadienyliron hexafluorophosphate and 4,4-bis(4-hydroxyphenyl)valeric acid to afford a bimetallic acid complex under the same reaction conditions (Scheme 1.6).112 O Cl  OH  Cl Fe+PF6-  + HO  OH K2CO3 DMF, r.t.  Cl  O  O  Fe+PF6-  Cl Fe+PF6-  O  OH  Scheme 1.6 Synthesis of bimetallic acid complex containing two cationic iron moieties. These carboxylic acid derivatives were reacted with terpyridine functionalized with hexanediol to yield esters. While there are many synthetic methods for the formation of esters between carboxylic acids and phenolic OH groups, Steglich esterification was employed 12  because  of  its  efficiency  and  mild  reaction  conditions.  The  reaction  utilizes  dicyclohexylcarbodiimide (DCC) as a coupling reagent and 4-methylaminopyridine (DMAP) as a catalyst,113 proceeding at room temperature for approximately 18-24 hours.  1.6 Organoiron-based polymers The incorporation of organoiron moieties into polymers results in materials with unique magnetic, optical, and electrochemical properties.114 The method of polymerization employed in the synthesis of most polymers described herein involves nucleophilic aromatic substitution of the chloro-terminated cyclopentadienyliron arene complexes. Dinucleophiles containing terminal hydroxyl groups were reacted with the chloro-functionalized monomers, leading to the isolation of organoiron-containing polymers. This approach has been thoroughly studied by the Abd-El-Aziz research group using dinucleophiles containing hydroxyl, amino, and thiol groups (Scheme 1.7).  Cl  Cl  X R X  Fe+PF6- + HX R XH where R = alkyl, aryl X = O, N, S  Fe+PF6n  Scheme 1.7 Synthesis of organoiron polymers via nucleophilic aromatic substitution.  1.7 Outlook While our research group has extensively studied metal-containing polymers with great focus on organometallic polymers containing cationic iron moieties,105–111,115–118 rarely have these materials fallen into the field of coordination polymers. The functionalization of the terpyridine moiety with established organoiron-containing complexes will enable the 13  formation of coordination polymers containing multiple metal centres, resulting in changes to their spectroscopic and thermal properties. Chapter 2 of this thesis presents the synthesis and characterization of novel functionalized terpyridines, both organic and organometallic in nature. Several new iron(II), ruthenium(II), and nickel(II) terpyridine complexes are reported, along with their characterization by NMR, IR, and UV-visible spectroscopy, as well as mass spectrometry. Chapter 3 describes the synthesis and characterization of four novel organoiron-containing coordination polymers based on the chelation of the functionalized terpyridine monomers to either iron(II) or nickel(II) metal centres. These polymers are prepared by either coordination polymerization or condensation polymerization. The thermal properties of the iron(II) polymers are investigated by thermogravimetric analysis and differential scanning calorimetry.  14  Chapter 2 Synthesis and Characterization of 4′-Substituted Terpyridines and Organoiron Terpyridine Complexes 2.1 Synthesis of organic functionalized terpyridines Two novel organic 4′-substituted terpyridines were synthesized for potential application in the preparation of a network of metal-chelated terpyridine polymers containing the organoiron complex. A third substituted terpyridine, first reported by Schubert and coworkers, was also prepared using a modified procedure that afforded a purer product in higher yield.24 A chloro group was first introduced to the 4′-position of terpyridine 2.2 to create an active site for nucleophilic substitution. The syntheses of trione 2.1, alcohol terpyridine (tpy-OH) 2.2, and chloroterpyridine (tpy-Cl) 2.3 were performed according to previously published methodologies by Constable and Ward (Scheme 2.1).19  O +  O  O  reflux, 6 h  N  O  NaH, DME  O  O  N  N 2.1 NH4OAc/EtOH reflux, 6 h  Cl  OH PCl5, POCl3 reflux, 6 h  N N  N  N N  2.3  N 2.2  Scheme 2.1 Synthesis of trione 2.1, tpy-OH 2.2, and tpy-Cl 2.3. Many synthetic methods were employed in the preparation of hexanediol terpyridine 2.4 that utilized the same reagents but different reaction conditions and work-up procedures. 15  The procedure reported by Schubert et al. was followed, with several changes to optimize product purity and yield (Scheme 2.2).24 However, several changes were made to this experimental procedure to aid in purer product and greater yield. Dry DMSO was used as the solvent, thus the reaction was performed under N2, which was not detailed in the reported methodology. A larger molar amount of the nucleophile was used in the reaction (the ratio of hexanediol to tpy-Cl 2.3 was increased from 1:1 to 5.5:1), resulting in greater yield, and the reagents were allowed to react for a longer duration (70 °C for up to two days).  HO  Cl + HO  N N  2.3  OH  KOH, DMSO 70 °C, 2 d  O  N N N  2.4  N  Scheme 2.2 Synthesis of hexanediol terpyridine 2.4. NMR spectroscopy confirmed the successful nucleophilic substitution at the 4′position of the terpyridine; a comparison of both 1H and 13C NMR spectra of tpy-Cl 2.3 and hexanediol terpyridine 2.4 is presented for ease of assignment of later novel substituted terpyridine compounds (Figure 2.1).  16  Cl f g  b  e  N N  2.3  h  N  HO  b  O f g  b  e  N N h  2.4  N e  f  h  9.0  8.9  8.8  1  8.7  8.6  8.5  8.4  8.3  8.2  8.1  8.0  g  7.9  7.8  7.7  7.6  7.5  7.4  7.3  7  Figure 2.1 H NMR spectra of tpy-Cl 2.3 (top) and hexanediol terpyridine 2.4 (bottom). The most significant difference between the 1H NMR spectra of starting material tpyCl 2.3 and a 4′-substituted terpyridine such as tpy 2.4 is the shift in the 3′,5′-proton signals. These protons appear as a singlet and shift upfield from 8.42 ppm to 7.96 ppm, indicative of 17  the ether functionality acting as a Lewis base and feeding electron density into the ring and therefore shielding the 3′,5′-hydrogens of the terpyridine. The other four terpyridyl proton environments remain relatively unaffected. In the rest of the 1H NMR spectrum, the methylene protons bonded to the ether oxygen at the 4′-position appear as a triplet at 4.24 ppm, an expected downfield shift due to the deshielding effect of the aromatic terpyridine system (Figure A.1.1). The methylene protons adjacent to the free OH group resonate at 3.41 ppm, while the hydroxyl proton itself appears at 4.35 ppm, confirming monosubstitution. Similarly, there are two characteristic peaks in the 13C NMR spectrum of hexanediol tpy 2.4 to confirm nucleophilic substitution of the starting material (Figure 2.2).  18  f g  e  b d  c N  N h  Cl a  N  2.3  OH  O a  b d f c N N g 2.4 h e  Figure 2.2  13  N  C NMR spectra of tpy 2.3 (top) and hexanediol terpyridine 2.4 (bottom).  Firstly, carbon Ca in tpy-Cl 2.3 moves dramatically downfield when substituted with oxygen, shifting from 145.4 ppm to 166.7 ppm. Carbon Cb, which bears the 3′,5′-protons, mirrors their upfield shift in the 1H NMR spectrum by shifting from 120.2 ppm to 106.7 ppm 19  in the  13  C NMR spectrum upon substitution. Though the oxygen atom acts as an electron  donor towards the surrounding proton environments, it is slightly more electronegative than chlorine and the C-O bond in tpy 2.4 is shorter than the C-Cl bond of starting material tpy 2.3, both of which contribute to the shifts in carbons Ca and Cb. This can also be shown using the resonance structures of tpy 2.4 (Figure 2.3). In C-O σ-bonds, there is significant electron donation from the oxygen to the carbon; in C=O π-bonds, the inductive effect competes with the electronic effect, leading to the deshielded carbon atom of the C-O bond.  R  R  O  N N  O  N N  N  N  Figure 2.3 Resonance structure of ether-substituted terpyridine. The IR spectrum of the product, tpy 2.4, indicates complete conversion from tpy-Cl 2.3 to hexanediol tpy 2.4 by the appearance of the diagnostic aryl C-O-CH2 stretches at 1203 cm-1 and 1020 cm-1 (Figure 2.4).119 Stretches in the 1400-1600 cm-1 region are a result of C=C and C=N stretching within the terpyridine unit. The aryl chloride stretch (1062 cm-1) of the starting material is not present, further confirming substitution at the 4′-position.  20  100 90  % Transmittance  80 70 60 OH  50 O  (CH2)6  40 N  30  N  20 4000  2.4  3500  N  3000  2500 2000 Wavenumbers (cm-1)  1500  1000  500  Figure 2.4 IR spectrum of hexanediol terpyridine 2.4. The first novel 4′-substituted terpyridine in this thesis, hydroxybenzyl alcohol terpyridine 2.5, was synthesized using a similar procedure as for hexanediol tpy 2.4 (Scheme 2.3).  OH  Cl + HO  N N  O  OH KOH, DMSO 60 °C, 2 d  N 2.3  N N  N 2.5  Scheme 2.3 Synthesis of 4-hydroxybenzyl alcohol terpyridine 2.5. Initially, the ether linkage was expected to form through the benzylic alcohol. Upon comparison of the pKa values of the two hydroxyl groups, the phenolic OH (pKa ~10) was 21  deprotonated ahead of the benzylic OH (pKa ~17) by potassium hydroxide. Despite the poor nucleophilicity of the resulting anion of the phenolic hydroxyl group, the duration and temperature of the reaction conditions, along with the excess amount of base, helped drive the successful substitution to near completion. The 1H NMR spectrum of hydroxybenzyl alcohol tpy 2.5 shows nucleophilic substitution by the upfield shift of the 3′,5′-protons of the terpyridine moiety (Hb) from 8.42 ppm in starting material tpy 2.3 to 7.93 ppm (Figure 2.5a). Signals representing the other four terpyridyl proton environments shift upfield no more than 0.08 ppm. The benzylic protons Hm shift downfield from 4.36 ppm to 4.57 ppm, and the aromatic protons of the hydroxybenzyl alcohol (Hj and Hk) also shift downfield to 7.27 ppm and 7.49 ppm, indicating a deshielding effect within the ring upon formation of the ether. This could be a result of the π system of the substituent coming into such close proximity of the terpyridyl π system. The hydroxyl proton (Hn) is present as a broad singlet at 5.31 ppm.  22  k j  (a)  f g  e  b  l  OH  n  O i a  d c N  N h  m  N 2.5  (b)  Figure 2.5 (a) 1H NMR spectrum and (b) 13C NMR spectrum of hydroxybenzyl alcohol tpy 2.5. * denotes starting material 4-hydroxybenzyl alcohol; all unlabeled peaks from 115-160 ppm in the 13C NMR spectrum represent unreacted starting material tpy 2.3. The  13  C NMR spectrum further supports the substitution of the 4′-position by the  downfield shift of carbon Ca, bearing the hydroxybenzyl alcohol moiety, from 145.4 ppm in tpy-Cl 2.3 to 166.8 ppm (Figure 2.5b). This shift can be attributed to the deshielding nature of the aromatic ring of the substituent. Carbon Cb shifts upfield as expected upon ether 23  functionalization, from 120.2 ppm to 108.1 ppm. Carbons Cc through Ch remain relatively unaffected by nucleophilic substitution. As in the synthesis of hexanediol terpyridine 2.4, nucleophilic aromatic substitution of tpy-Cl 2.3 was employed to afford carboxylic acid-functionalized terpyridine 2.6, using 4mercaptobenzoic acid as the nucleophile (Scheme 2.4).  O Cl  OH + SH  N N  2.3  OH DMF  S  O  N  N N  2.6  N  Scheme 2.4 Synthesis of acid terpyridine 2.6 The 1H NMR spectrum of acid terpyridine 2.6 shows an upfield shift of the 3′,5′protons from 8.42 ppm to 8.33 ppm, demonstrating successful nucleophilic substitution. The four other proton environments on the terpyridine moiety shift downfield, with the 3,3″protons shifting downfield the most from 8.03 ppm to 8.24 ppm. The aromatic protons of the attached 4-mercaptobenzoic acid appear as two doublets, both shifting downfield from their positions in the 1H NMR of the starting material due to their proximity to the electronwithdrawing π system of the terpyridine. The two protons closest to the acid functionality move from 7.97 ppm to 8.07 ppm, while the aromatic hydrogens closest to the sulfur linkage shift less dramatically from 7.66 ppm to 7.77 ppm. Similarly, the 13C NMR spectrum of acid tpy 2.6 shows shifts in the aromatic carbon peaks of the 4-mercaptobenzoic acid moiety for the same reason (Figure 2.6). While the peaks representing Cc and Cd barely change from  24  their respective resonances in the starting material, Ca shifts upfield from 140.8 ppm to 135.1 ppm as a result of the reduced electronegativity of sulfur compared to chlorine.  O d  S a  OH  c b  N N  2.6  N  Figure 2.6 Portion of 13C NMR spectrum of acid terpyridine 2.6, showing the aromatic carbon signals of the 4-mercaptobenzoic acid moiety. The infrared spectrum of acid terpyridine 2.6 displays a C=O stretch at 1705 cm-1 and a C-O stretch at 1261 cm-1, indicative of a carboxylic acid moiety (Figure A.2.1). In addition to the expected C=C and C=N stretches of terpyridine at 1573 cm-1, 1523 cm-1, and 1400 cm1  , an aryl thioether C-S stretch is found at 675 cm-1.119,120 Upon comparison of the UV-visible absorbance spectrum of acid tpy 2.6 to that of  hexanediol tpy 2.4, the effect of substitution of the 4′-position with different atoms is illustrated (Figure 2.7). One of the π → π* transitions appears at 241 nm in oxygensubstituted tpy 2.4, and undergoes a hypsochromic, or blue, shift in sulfur-substituted tpy 2.6 to appear at 232 nm. Meanwhile, the shift of a second π → π* transition within the pyridyl ring is bathochromic, or red, absorbing at 276 nm in tpy 2.4 and 289 nm in tpy 2.6. These 25  shifts could be caused by the electron-withdrawing properties of the thiol group bonded to the aromatic carboxylic acid.121,122 A band corresponding to an n → π* transition is expected in a molecule containing terpyridine, denoting the movement of an electron from a nonbonding lone pair of a nitrogen of one of the three pyridyl rings to an antibonding π* orbital. These transitions typically lie at a lower energy than π → π* transitions and are expected around 330-360 nm in terpyridine moieties.123–129 However, in the solution absorption spectra of pyridines and similar compounds, the n → π* transition are often not observed.130,131 In addition, there is the possibility of potential overlap with the peak of the lowest energy π → π* transition in these substituted terpyridines, and therefore the band representing the n → π* transition does not appear in the UV-vis spectrum of either hexanediol tpy 2.4 or acid tpy 2.6. 1.2  Normalized absorbance  1 0.8 0.6 0.4 0.2  hexanediol tpy 2.4 acid tpy 2.6  0 220 -0.2  260  300  340  380  420  460  Wavelength (nm)  Figure 2.7 Comparison of UV-visible spectra of hexanediol terpyridine 2.4 (red) and acid terpyridine 2.6 (blue) in the region of 220-480 nm. 26  Solvent interactions can play a pivotal role in shifts in UV-visible absorbance spectra, leading to band broadening and both red and blue shifts in absorption bands.131 A more polar solvent can cause a blue shift in n → π* transitions due to the interaction between the lone pair and the solvent, allowing solvent molecules to align themselves with the ground state. When the excited state emerges, the solvent molecules do not have time to rearrange in order to stabilize the excited state, resulting in a lower energy ground state. The opposite is true for the effect of polar solvents on π → π* transitions, which can undergo a red shift due to either an increase in the ground state energy or a drop in the excited state energy. If the excited state is polar, it will be solvent stabilized, therefore lowering the energy of the transition and causing the absorbance band to appear at a longer wavelength. The solvent used for all UVvisible spectroscopy was acetonitrile, which is quite polar, and therefore these effects were anticipated.  2.2 Synthesis of organoiron-containing terpyridines Abd-El-Aziz and coworkers have performed widespread research in the field of organoiron complexes, utilizing ligand exchange reactions between ferrocene and pdichlorobenzene, followed by functionalization with carboxylic acids, alcohols, azo dyes, norbornene, and many other functional groups.105–112,115,117,118 Two novel organoironcontaining carboxylic acid complexes were synthesized to join this already extensive catalogue of organoiron compounds. Organoiron complex 2.8 was prepared using a previously reported method established by Abd-El-Aziz et al.115 A metal-mediated nucleophilic reaction was performed with complex 2.7 and 4-hydroxyphenylacetic acid in the presence of K2CO3 (Scheme 2.5). 27  Cl  Cl Fe+PF6-  +  K2CO3  HO O  OH  Cl  DMF 18 h, dark  O Fe+PF6-  O  OH  2.8  2.7  Scheme 2.5 Synthesis of acid complex 2.8. The 1H and  13  C NMR signals representing the protons of the complexed arene,  coordinated to the iron centre, appear at a significantly lower chemical shift range (6.5-7.0 ppm) than non-complexed arene rings (7.2-8.5 ppm), providing a point of reference when interpreting the NMR spectra of compounds containing this cationic iron group. The destabilization of the anisotropy of the arene, caused by the coordination of the π system to the iron centre, results in this upfield shift. Also, the Cp ring produces a characteristic singlet between 5.45 and 5.55 ppm in the 1H NMR spectra of most arene-coordinated organoiron complexes. Due to the unique chemical shifts of the signals of these two proton environments, they are extremely useful as diagnostic peaks for confirmation of reaction success and completion. Successful nucleophilic substitution on the complexed arene ring of complex 2.7 is easy to determine by the shift in the strong singlet of the Cp protons from 5.48 ppm to 5.41 ppm, which correlate to the Cp carbon peak at 80.5 ppm in the gHSQC NMR spectrum (Figure 2.8).  28  b  c  e  O  f  PF6-  O  Cl Fe  d  +  OH  a 2.8  f  c  a  b  d e  Figure 2.8 gHSQC NMR spectrum of acid complex 2.8. * denotes starting material complex 2.7 The complexed aryl protons appear as doublets at 6.85 and 6.52 ppm, while the noncomplexed aryl protons appear at 7.53 and 7.32 ppm. The methylene protons appear as a singlet at 3.74 ppm. The 1H NMR spectrum shows a small amount of unreacted 4hydroxyphenylacetic acid, most likely due to the 1:4 ratio of complex 2.7 to acid. Meanwhile, the signals of complexed aromatic carbons Cb and Cc resonate at 87.9 ppm and 77.2 ppm, respectively. These values are comparable to the analogous chemical shifts of similar cyclopentadiene-containing cationic iron complexes.105,107,108,115 The non-complexed aromatic carbons appear in the expected aromatic region of the 13C NMR spectrum, with Cd resonating 29  at 121.5 ppm and Ce at 132.8 ppm. Both Cb and Ce are more deshielded due to their metaposition with respect to the more electronegative oxygen atom on the rings. Carbon Cf of the methylene group appears at 40.4 ppm, while the carbon of the carboxylic acid group appears most downfield at 172.5 ppm. The quaternary carbons of the complexed benzene rings can be found at very different shifts: the carbon bonded to the chlorine atom appears at 105.0 ppm, while the carbon bonded to the oxygen atom resonates at 134.0 ppm. Similarly, the quaternary carbon of the non-complexed benzene ring bonded to the oxygen appears at 152.9 ppm due to the electron-withdrawing properties of oxygen, while the carbon bearing the –CH2COOH moiety shows a peak at 134.7 ppm. Diacid complex 2.9 was synthesized using the same procedure as was employed for acid complex 2.8. A similar complex already exists within the reported array of organoiron compounds, but with either a single carboxylic acid group or two aldehyde moieties.107,115 The diacid complex 2.9 was therefore prepared to later afford an organoiron-containing monomer with two terminal terpyridine moieties through an esterification reaction (Scheme 2.6).  Cl  Cl Fe+PF6- + HO  O O  K2CO3  OH DMF  2.7  HO  O  O Fe+PF6-  O OH  2.9  Scheme 2.6 Synthesis of diacid complex 2.9. In the 1H NMR spectrum of complex 2.9, the Cp singlet appears at 5.43 ppm, slightly downfield from its resonance in complex 2.7 at 5.48 ppm, confirming substitution (Figure A.1.14). The complexed aryl protons (Hb) appear as a singlet at 6.59 ppm, further supporting  30  successful disubstitution, as monosubstitution would result in two doublets. Meanwhile, the proton signals of the non-complexed arene show doublets at 8.17 ppm (Hf) and 7.43 ppm (He). No peaks representing either starting material appear in the spectrum, confirming completion of the reaction. The quaternary carbons are easy to assign with the help of the gHMBC NMR spectrum of diacid complex 2.9 (Figure 2.9).  O HO  b c  O  O  d  Fe+PF6-  e  f  g O h  OH  a  2.9  Figure 2.9 Aromatic region of the gHMBC NMR spectrum of diacid complex 2.9. The Ar-CH protons of the non-complexed aromatic ring closest to the ether oxygen, He, show a correlation to both quaternary carbons of the ring: Cd appears at 158.8 ppm (2J 31  correlation) and Cg appears at 129.1 ppm (3J correlation). Proton Hf correlates to both of these carbons as well, but is the only proton to 3J couple to the carbon of the carboxylic acid moiety at 166.6 ppm. Finally, the complexed aromatic protons Hb 2J couples to Cc at 130.8 ppm. A typical carbonyl stretch of a carboxylic acid group on an aromatic ring appears at 1697 cm-1 in the IR spectrum of diacid complex 2.9, while the C-O stretching band occurs at 1288 cm-1. The stretches at 1232 cm-1 and 1128 cm-1 demonstrate the stretching of the diaryl ether C-O-C bonds, supporting the formation of the ether bond (Figure 2.10). The UV-vis spectrum shows one band at 246 nm, representing the π → π* transition of the aromatic rings (Figure A.3.1).  120 110  % Transmittance  100 90 80  O  70 60  O  HO  O Fe+PF6-  O OH  50  2.9 40 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  1500  1000  500  Figure 2.10 IR spectrum of diacid complex 2.9.  32  The first organoiron-containing terpyridine compound was prepared via a condensation reaction with acid complex 2.10 (previously prepared by Abd-El-Aziz and coworkers) and hexanediol terpyridine 2.4 (Scheme 2.7).108,115 HO  Cl  O Fe+PF6-  O OH  +  DCC, DMAP O  DCM  Cl  O Fe+PF6-  2.10 2.4  O (CH2)6 O  N N  2.11  N N  N  O  N  Scheme 2.7 Synthesis of organoiron-containing terpyridine 2.11. Some of the stable byproduct, dicyclohexyl urea (DCU), was still present in the final product despite purification attempts, causing the percent yield to be greater than 100%. Though this byproduct has relatively low solubility in many common solvents, such as water, dichloromethane, and acetone, some amount of DCU tends to remain in several otherwise pure samples, especially those in which the reaction solvent was N,N’-dimethylformamide. Therefore, its proton resonances appear in some of the NMR spectra included herein. However, the peaks representing the proton environments of DCU do not greatly interfere with most diagnostic peaks in the NMR spectra of the reported terpyridine-based materials. The gHSQC NMR spectrum shows that the signal at 4.33 ppm represents both the methylene protons adjacent to the ester, shifted downfield from 4.24 ppm in tpy 2.4, as well as the methylene protons adjacent to the oxygen bonded to the terpyridine (Figure 2.11a). Though one proton signal is present, the resonance correlates to two different carbon peaks: 64.9 ppm (Ca) and 68.5 ppm (Cb). Finally, the gHMBC spectrum shows a correlation between Ha and Cc, confirming the formation of the ester bond (Figure 2.11b). 33  Cl  O Fe+PF6-  O c  O a  N b O  2.11  d  N N  (a)  (b)  Figure 2.11 (a) gHSQC spectrum displaying the 3JCH correlation of Ha and Hb to Ca and Cb in complex 2.11; (b) gHMBC spectrum of complex 2.11 showing the 3JCH correlation of Ha and Hb to Cc and Cd, respectively. 34  The IR spectrum of complex 2.11 shows a shift in the C=O stretch to a higher wavenumber (1710 cm-1) than the starting material (Figure A.2.2). Aryl ester C=O stretches occur at a lower frequency than those of aliphatic esters due to the increased conjugation. The carbon-carbon and carbon-nitrogen double bond stretches of the terpyridine moiety are present in the region from 1400-1650 cm-1, and the =C-N stretch is found at 1357 cm-1. The C-O-C stretches of the ester functionality appears at 1278 cm-1 and 1161 cm-1, confirming a successful reaction. Diacid 2.9 was reacted with hexanediol terpyridine 2.4 in a Steglich esterification reaction using the same conditions as in the preparation of complex 2.11 to afford complex 2.12 with two terminal terpyridine groups (Scheme 2.8). HO O  O  HO  O  O  OH  Fe+PF6-  + O  2.9 N N  2.4  N  DCC, DMAP DCM N  O N  N  O (CH2)6 O  O  O Fe+PF6-  N  O O (CH2)6 O  N N  2.12  Scheme 2.8 Synthesis of organoiron-containing terpyridine 2.12. The 1H NMR of complex 2.12 shows the product peaks, as well as the presence of some diacid starting material, in a ratio of approx. 5:1 (Figure 2.12). The ester groups are 35  slightly less deshielding than the acid groups of starting organoiron complex 2.9, causing a small shift upfield in the resonances of the cyclopentadienyl protons and the complexed and non-complexed aryl hydrogens. N  O N  N  O (CH2)6 O  O  O Fe+PF6-  N  O O (CH2)6 O  N N  2.12  Figure 2.12 1H NMR spectrum of complex 2.12. * denotes dicyclohexyl urea impurity132 As in monosubstituted complex 2.11, the multiplet at 4.32 ppm represents both the methylene protons next to the ester group and those adjacent to the oxygen bonded to the terpyridine group, as confirmed by gHSQC data (Figure 2.13).  36  .  N  O N  O  O (CH2)6 O  O  O  O  Fe+PF6-  N  a N bO  N N  2.12  61 62 63 64  a  65 66 67 68  b  69 70 71 72 73 74 4.55  4.50  4.45  4.40  4.35  4.30  4.25  4.20  4.15  4.10  Figure 2.13 gHSQC spectrum of complex 2.12 displaying the 3JCH correlation of Ha and Hb to Ca and Cb. Both signals have shifted downfield from their corresponding peaks in starting material hexanediol terpyridine 2.4, though the shift is much more dramatic in the case of the CH2 hydrogens near the ether functionality, which resonate at 3.41 ppm in tpy 2.4 due to their proximity to the free hydroxyl group. The  13  C NMR data confirms a similar shift in the  corresponding carbon environments: carbon Ca, bearing the methylene protons adjacent to the ester group, shifts from 60.6 ppm to 64.8 ppm, while carbon Cb, bonded to the ether functionality, shifts to 68.5 ppm from 67.9 ppm, demonstrating successful esterification.  37  As in monosubstituted complex 2.11, complex 2.12 with diester functionalities shows similar IR stretches to confirm the successful esterification reaction (Figure A.2.3). The C=O stretch shifts from 1697 cm-1 in starting material diacid complex 2.9 to 1710 cm-1, while the C-O-C ester stretches occur at 1271 cm-1 and 1165 cm-1. The terpyridine C=C and C=N stretching frequencies appear in the 1400-1650 cm-1 region, shifting to slightly higher wavenumbers than in starting material hexanediol tpy 2.4. The =C-N stretch follows the same trend, shifting approximately 20 cm-1 higher in frequency to 1346 cm-1 than its equivalent in tpy 2.4. This shift to lower energy could be a result of some intramolecular or intermolecular interaction; the hexyl chains are fairly flexible, allowing the terpyridine units to potentially interact with nearby terpyridine groups or the second terminal terpyridine group within the same molecule. The UV-vis spectra of complexes 2.11 and 2.12 are very similar, showing matching absorbance bands in the 220-360 nm range (Figure 2.14). The peaks at 245 nm and 275 nm represent the π → π* transitions of the terpyridyl groups. The absorbance band at 245 nm also overlaps with the peak representative of the π → π* transition of the aromatic rings of the cationic iron ester moiety, which appears at 246 nm in the UV-vis spectra of starting materials diacid 2.9 and monoacid 2.10.  38  1.2  Normalized absorbance  1 0.8 0.6 0.4 0.2  complex 2.11 complex 2.12  0 220 -0.2  260  300  340  380  420  460  Wavelength (nm)  Figure 2.14 Comparison of UV-visible spectra of complex 2.11 (red) and complex 2.12 (blue) in the region of 220-480 nm. A small peak is present at 315 nm, with a small shoulder at 327 nm, which most likely coincides with a small amount of iron-chelated terpyridine byproduct, as a similar transition appears in the UV-vis spectra of later iron-chelated complexes. There are no peaks indicative of an iron(II)-bisterpyridine complex in the NMR spectra of complexes 2.11 and 2.12. However, the impurity could be an iron complex with a monoterpyridine ligand, such as (tpy)FeCl2 or (tpy)FeCl3, both of which are paramagnetic and would not give rise to resonances within the 0-14 ppm range of the 1H NMR spectra.62  39  2.3 Synthesis of terpyridine-based metal-chelated complexes A set of three novel metal-chelated complexes of hexanediol terpyridine 2.4 were prepared to demonstrate a small portion of the range of possible metal-organic frameworks containing terpyridines. The three metal-chelated complexes employed either iron(II), ruthenium(II), or nickel(II). Iron(II) was used for the complexes and coordination polymers in Chapter 3 due to the facile and efficient reaction conditions, minimal purification required, and diamagnetic properties. The iron(II)-chelated terpyridine complexes were all synthesized by a modification of a published procedure (Scheme 2.9).133 The product was a deep purple powder, the expected colour of iron-terpyridine complexes.76,83,133–153 OH (CH2)6 O FeCl2·4H2O + N N  2.4  N  MeOH NH4PF6  N HO  O  N Fe2+ N  N N  N  OH  O 2 PF6-  2.13  Scheme 2.9 Synthesis of [Fe(hex-typ)2][PF6]2 (complex 2.13). The iron(II)-chelated terpyridine complexes were soluble in acetone, but all NMR experiments were performed in DMSO-d6 for ease of comparison to the spectral data of the terpyridine starting materials. The 1H NMR spectrum of complex 2.13 showed significant 40  shifts in all of the proton environments of the terpyridine moieties in response to chelation to iron (Figure 2.15).  e HO o n  m  k l  N  b  i j  f  O  g h  N  Fe2+ N  N N  OH  O 2 PF6-  N  b  2.13  n g  e  h  f  i  m,n j  l  o  9.5  9.0  8.5  8.0  7.5  7.0  6.5  6.0  5.5  5.0  4.5  4.0  3.5  3.0  2.5  2.0  1.5  1.0  Figure 2.15 1H NMR spectrum of iron-chelated complex 2.13. The singlet representing the 3′,5′-protons (Hb) shifts downfield from 7.97 ppm to 8.93 ppm, while the 3,3″-protons (He) shift downfield from 8.60 ppm to 8.83 ppm. The 4,4″-proton (Hf) resonance shows little variation as a triplet of doublets at 7.97 ppm, while both the 5,5″and 6,6″-protons (Hg and Hh) move upfield to 7.17 and 7.23 ppm, respectively. These upfield shifts are in direct response to chelation to the iron(II) centre, which accepts electrons from the terpyridine nitrogens. The lone pairs on the nitrogens contribute less to the electron density in the pyridyl rings, decreasing the electron density in the aromatic system, and therefore shielding the protons nearest the iron moiety. The upfield shifting of protons Hh can 41  be explained by their position in the shielding region above a pyridine ring of the other ligand.154 The shifting of protons Hb depends upon the nature of the substituent, but these hydrogens often resonate near protons He. The methylene protons next to the ether linkage (Hi) shift slightly downfield, appearing at 4.62 ppm. This shift is most likely due to the metal centre pulling electron density away from the terpyridine moiety as a whole, thus causing the aromatic terpyridyl system to deshield the surrounding proton environments. A broad triplet is present at 4.72 ppm, indicating Ho of the intact hydroxyl group. All resonances representing the terpyridyl carbons shift slightly downfield in the 13C NMR spectrum of complex 2.13, compared to their positions in starting material tpy 2.4 (Figure 2.16). The carbon of the methylene group bonded to the oxygen of the ether (Ci) also moves downfield from 67.9 ppm to 70.0 ppm.  42  f  g  e i  HO  O  a  2.4  f  HO  a  N  h  b c d N  O  N  g  e i  h  b c d N  N Fe2+ N  N N  N  OH  O 2 PF6-  2.13  Figure 2.16 Comparison of the 13C NMR spectra for hexanediol tpy 2.4 (top) and its iron-chelated complex 2.13 (bottom). The UV-vis spectrum of iron(II) complex 2.13 shows the expected π → π* transitions of the terpyridine moiety at 244 nm and 271 nm, along with a new peak at 315 nm to demonstrate the changes in the π → π* transitions upon chelation to the iron centre (Figure 2.17).155 In addition, a broad metal to ligand charge transfer (MLCT) band appears at 555 nm, 43  indicating successful chelation of the terpyridine to iron.76,137,138,144,150–152 The small band at 365 nm represents a metal-centred d-d transition, as does the shoulder peak at 511 nm.76,137,144 1.6 HO  O  1.2  Fe2+ N  N N  1 Absorbance  N  N  1.4  OH  O 2 PF6-  N  2.13  0.8 0.6 0.4 0.2 0 220 -0.2  300  380  460  540  620  700  780  Wavelength (nm)  Figure 2.17 UV-visible spectrum of iron(II)-chelated complex 2.13. [Ni(hex-tpy)2][PF6]2 (complex 2.14) was prepared using a modified procedure reported by Chernyshev and coworkers (Scheme 2.10).156  44  OH (CH2)6 O Ni(CH3COO)2·4H2O  + N N  2.4  N  MeOH NH4PF6  N HO  O  N Ni2+ N  N N  N  OH  O 2 PF6-  2.14  Scheme 2.10 Synthesis of [Ni(hex-tpy)][PF6]2 (complex 2.14). Due to its paramagnetic nature, the 1H NMR spectrum of the complex did not appear useful. However, according to a similar reaction reported by Constable and coworkers using cobalt(II), signals outside of the studied 0-14 ppm range would have provided information regarding the terpyridyl protons.82 The MALDI-TOF mass spectrum of complex 2.14 is consistent with its structure by displaying the molecular ion peak [M+PF6]+ at m/z 901.24 (m/z calculated for C42H46 NiN6O4PF6: 901.257) (Figure 2.18).  45  Figure 2.18 Ma ass spectrum m of compleex 2.14, shoowing the m molecular ion n peak [M+ +PF6]+ at m//z 901.24. In additio on, the UV-v vis spectrum m shows a b athochromicc shift in thee ligand-cenntred π → π* transitionss to 311 nm m and 322 nm, n which ccoincides wiith similar sshifts observved in previiously reportted substituteed terpyridin ne nickel(II) complexes (Figure 2.199).137  46  4 N  3.5 HO  O  3  N Ni2+ N  N N  OH  O 2 PF6-  N  Absorbance  2.5 2.14  2 1.5 1 0.5 0 220  270  -0.5  320  370  420  470  520  Wavelength (nm)  Figure 2.19 UV-visible spectrum of nickel(II)-chelated complex 2.14. The ruthenium(II) analogue of the three previous compounds, complex 2.15, was synthesized by a standard preparation developed by Constable in 1985, which utilized unsubstituted terpyridine as the chelating groups rather than the 4′-substituted hexanediol terpyridine 2.4 (Scheme 2.11).157  47  OH (CH2)6 O RuCl3·3H2O + N N  2.4  N  EtOH, NH4PF6 reflux  N N HO  O  Ru2+ N  N  N N  OH  O 2 PF6-  2.15  Scheme 2.11 Synthesis of [Ru(hex-tpy)2][PF6]2 (complex 2.15). The proton signals of the 1H NMR spectrum of complex 2.15 demonstrate the anticipated shifts as detailed by previous research groups working with ruthenium-chelated terpyridine complexes (Figure 2.20).152,157–163  48  c b j  HO k  h i  g  N  a  f  O  d  N  e  N  Ru2+ N N  N  OH  O 2 PF6-  2.16  Figure 2.20 1H NMR spectrum of complex 2.15. As in iron-chelated complex 2.13, the 3′,5′-protons (Ha) shift downfield upon chelation. However, in the ruthenium-based compound, these hydrogens shift only to 8.39 ppm from 7.96 ppm in starting material tpy 2.4, a less significant shift than 8.93 ppm as witnessed in the iron(II) complex. This can be attributed to ruthenium being slightly less deshielding than iron as a metal centre, as observed in previous iron(II) and ruthenium(II) terpyridine complexes.76,137,151,152,164,165 The resonances indicative of protons Hd and He shift upfield as they did in the iron(II) analogue to 7.24 ppm and 7.48 ppm, respectively. This confirms that chelation to a transition metal has a shielding effect on these particular protons, regardless of the metal involved, due to the electron-donating properties of the terpyridine ligands to the metal centre. These upfield shifts may be attributed to van der Waals interactions, though the interaction of the metal with the central ring of the terpyridine moiety 49  is alsso greater than that with h the terminaal rings.154 T The signals rrepresenting Hb and Hc ddo not shift dramatically y compared to starting material tpyy 2.4. The pprotons of thhe alkyl chaain all shift slightly dow wnfield, mostt notably Hf from 4.24 pppm to 4.53 pppm. The MAL LDI-TOF mass m spectrum m of compllex 2.15 shoows several fragments of the propo osed structure, none of which inclu ude any hexaafluorophospphate ions ((Figure 2.21). The peak at m/z 799.2 25 representts [Ru(2.4)2-H] - +, the com mplex minuss a hydrogenn. The peak at m/z 16 correspon nds to the fraagment [Ru(2.4)(tpyO)]+ , the compleex with one -(CH2)6OH group 699.1 remo oved. Similarrly, the fragm ment [Ru(tp pyO)2]+ withh both hexannol groups reemoved appeears at m/z 598.06. 5  Figure 2.21 Porrtions of thee mass specttrum of com mplex 2.15. 50  IR spectroscopy of metal-chelated complexes 2.13 through 2.15 reveals a clear shift to higher wavenumbers of the terpyridine-based stretch vibrations. The C=C and C=N stretches still appear within the region of 1400-1650 cm-1, but shifted to the left compared to the free ligand, hexanediol tpy 2.4. Similarly, the =C-N stretch at 1359 cm-1 shifts to 1365 cm-1, while the aryl C-O-CH2 ether stretches consistently shift to higher wavenumbers as well (1217 cm-1 and 1041 cm-1 for Fe(II) complex 2.13 and 1257 cm-1 and 1018 cm-1 for Ru(II) complex 2.15, for example). The frequencies of these ligand-based vibrations are comparable to those of similar terpyridine complexes of these metals previously established in the literature, which confirms that chelation to iron, nickel, or ruthenium raises the force constant of the bonds within the terpyridine moieties.31,137,144,151,165–169 The UV-visible spectrum of complex 2.15 shows an intense peak at 303 nm, illustrating the change in the π → π* transitions of the terpyridine groups, while a broad MLCT band at 486 nm is indicative of chelation to ruthenium(II).76,122,138,144,149–152,154,164,165,170,171 The other π → π* transitions of the terpyridyl moiety appear as two bands at 240 nm and 266 nm. Complexes 2.16 and 2.17 were prepared by stirring FeCl2·4H2O and either alcoholfunctionalized tpy 2.5 or acid-functionalized 2.6 in methanol at room temperature for 30 minutes (Scheme 2.12).  51  R  N N + FeCl2·4H2O  N N  MeOH NH4PF6  N 2.5 R =  O  2.6 R =  S  CH2 OH O  R  N  Fe2+ N N N  R 2 PF6-  2.16 2.17  OH  Scheme 2.12 Synthesis of iron-chelated complexes 2.16 (where R = hydroxybenzyl alcohol) and 2.17 (where R = 4-mercaptobenzoic acid). 1-D and 2-D NMR spectroscopy demonstrates that the terpyridyl proton and carbon environments for both complexes shift as expected upon chelation to iron (Appendices Error! Reference source not found. and Error! Reference source not found.). The resonance for the 3′,5′-protons (Hb) shift downfield in both 2.16 and 2.17 to appear as a singlet at 8.91 ppm and 9.06 ppm, respectively (Table 2.1).  52  Table 2.1 Summary of 1H and 13C NMR chemical shifts for complexes 2.16 and 2.17.  f  g h  e N b c d R a  N  2.16 R =  N Fe  2+  N  N  R 2.17 R =  2 PF6-  j  Complex 2.17  Complex 2.18  1  1  H  -8.91 --8.78 7.94 7.20 7.36 -7.57 7.62 -4.66  13  C  166.4 113.6 160.8 157.5 124.1 138.6 127.6 153.2 152.7 119.8 128.6 140.2 62.4  H  -9.06 --8.73 7.95 7.19 7.29 -8.03 8.18 ---  13  OH m  l  O  k  i  S  l  i j  N  a b c d e f g h i j k l m  O  k  m  OH  C  149.6 122.2 159.3 157.1 124.2 138.8 127.8 153.1 134.6 132.6 131.1 132.9 166.9  Once again, the protons most affected by the chelation are the 5,5″- and 6,6″hydrogens (Hg and Hh) of the terpyridyl moieties due to their proximity to the metal centre. In complex 2.16, hydrogens Hg shift to the right from 7.50 ppm in hydroxybenzyl alcohol tpy 2.5 to 7.20 ppm; the same proton signals in complex 2.17 shift from 7.70 ppm in acid tpy 2.6 to 7.19 ppm. Hydrogens Hh are affected even more dramatically, shifting upfield from 8.67 ppm and 8.78 ppm in starting materials tpy 2.5 and 2.6 to 7.36 ppm in complex 2.16 and 7.29 ppm in complex 2.17, respectively. The 1H NMR peaks of the R-groups remain relatively unaffected by chelation to iron, including aromatic protons Hj and Hk in both complexes, as 53  well as methylene hydrogens Hm in complex 2.16. The 13C NMR chemical shifts of carbons Ci through Cm are also very similar to those of the starting materials, confirming that chelation to a metal centre has a much stronger effect on the NMR resonances of the terpyridyl group than the moieties substituted at the 4′-position. Chelation to iron causes the terpyridyl stretches in the IR spectra of complexes 2.16 and 2.17 to move to higher wavenumbers. Both complexes have C=C and C=N stretching frequencies in the range of 1400-1650 cm-1. In complex 2.16, the O-H stretch is found at 3107 cm-1, while the C-O stretch of the alcohol appears at 1022 cm-1. The aryl C-O-C stretches occur at 1224 cm-1 and 1014 cm-1. The infrared spectrum of complex 2.17 shows a lower frequency shift for the C=O stretch of the carboxylic acid group (1705 cm-1 to 1693 cm-1), though the C-O and aryl C-S stretches shift to higher wavenumbers (1276 cm-1 and 690 cm-1, respectively). The visible regions of the absorption spectra of complexes 2.16 and 2.17 show fairly intense MLCT bands at 557 nm and 568 nm, respectively. The small shoulders at ~364 nm and ~511 nm in both spectra represent a d-d transition based on the iron(II) centre. The π → π* transitions in sulfur-substituted terpyridine complex 2.17 appear at slightly higher wavelengths lower energies than those found in complex 2.16 with oxygen in the 4’-position, suggesting these transitions occur at a lower energy. The ligand-centred π → π* transition affected by chelation to iron is present in both spectra as well, at 315 nm in complex 2.16 and 319 nm in complex 2.17.  54  1.2  Normalized absorbance  1 0.8 0.6 0.4 0.2  complex 2.16 complex 2.17  0 200 -0.2  300  400  500  600  700  800  Wavelength (nm)  Figure 2.22 UV-visible spectra of complexes 2.16 (red) and 2.17 (blue).  2.4 Experimental General considerations. All reagents were purchased from Sigma-Aldrich, Alfa Aesar, or VWR, and used without further purification. Phosphorus oxychloride (POCl3) was stored under N2 upon opening. All solvents were HPLC grade from Fisher Scientific and used without further purification. Compounds 2.1, 2.2, and 2.3 were synthesized via established procedures with minor modifications.19 Instead of dissolution in diethyl ether to remove excess water, trione 2.1 was dissolved in an ether/CHCl3 mixture. For alcohol terpyridine 2.2 (tpy-OH), either an ethanol/water mixture was used as the recrystallization solvent instead of ethanol, or the crude product was deemed pure via NMR spectroscopy without 55  recrystallization. Complexes 2.7 and 2.10 were prepared by previously published procedures established by the Abd-El-Aziz research group.108 All reactions and complexes containing an η6-dichlorobenzene-η5-cyclopentadienyliron(II) hexafluorophosphate moiety were kept in the dark to prevent decomposition. Characterization. NMR spectral data were collected on a Varian Mercury Plus Spectrometer (400 MHz), with an ATB tunable multinuclear probe with a gradient channel. Chemical shifts were referenced to residual solvent peaks and coupling constants were reported in Hz. Infrared spectra were recorded on a Shimadzu IRPrestige-21 spectrophotometer with neat samples on a MIRacle A diamond ATR accessory from PIKE Technologies. UV-visible measurements were performed using a Shimadzu UV-2550 spectrophotometer with a standard 1 cm2 quartz cell at 25 ± 1 °C; spectra were recorded for ≈ 10-5 M solutions in CH3CN. Matrix-assisted laser desorption ionization (MALDI) mass spectra were obtained on a Bruker Autoflex MALDI time-of-flight (TOF) spectrometer in reflectron  mode,  using  a  matrix  of  trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-  propenylidene]malononitrile (DCTB). For solvent-free MALDI approach, the solid sample was mixed with matrix in a 1:1 ratio (by weight) and the solid mixture was applied to the MALDI target. For solvent-based MALDI sample preparation, a stock solution was made at ~1 mM in CH3CN and mixed with the DCTB solution. One μL of the mixture solution was then deposited onto the sample target. Calibration was performed externally using various peptides and proteins of similar molecular weights as the compounds analyzed. Hexanediol terpyridine 2.4. The procedure was obtained by modifying and combining multiple established methods to optimize the reaction for both highest yield and purest product.24,25,44,151,172 To a stirred suspension of powdered KOH (0.4064 g, 5.5 mmol) and dry DMSO (8 mL) under N2 at 80 °C, 1,6-hexanediol (1.0833 g, 5.5 mmol) was added 56  and the reaction was heated for 30 min. Tpy-Cl 2.3 (0.1564 g, 1 mmol) was added and the mixture was stirred for 4 h at 70 °C. The reaction was poured into water (75 mL) and extracted into DCM three times. The organic product was dried with Na2SO4, filtered, and the solvent was removed in vacuo. The product was isolated as a white, foul-smelling powder (0.3960 g, 86% yield). 1H NMR (400 MHz, DMSO-d6) δ 8.71 (ddd, J = 4.7, 1.7, 0.9, 2H), 8.61 (dt, J = 7.9, 1.0, 2H), 8.00 (td, J = 7.8, 1.8, 2H), 7.96 (s, 2H), 7.50 (ddd, J = 7.5, 4.7, 1.1, 2H), 4.35 (t, J = 5.0, 1H), 4.24 (t, J = 6.5, 2H), 3.41 (dd, J = 11.4, 6.2, 2H), 1.81 (pent, J = 6.9, 2H), 1.46 (m, 4H), 1.39 (m, 2H). 13C NMR (100 MHz, DMSO-d6) δ 166.7, 156.6, 154.9, 149.2, 137.3, 124.5, 120.9, 106.7, 67.9, 60.6, 32.5, 28.5, 25.3, 25.2. IR: 3325 (O-H), 1560, 1469, 1444, 1406 (C=C, C=N), 1359 (=C-N), 1203, 1020 (aryl C-O-CH2). UV-vis λmax/nm (CH3CN) 241, 276. Hydroxybenzyl alcohol terpyridine 2.5. 4-Hydroxybenzyl alcohol (0.5817 g, 5 mmol) was dissolved in dry DMSO (7 mL). While stirring, powdered KOH (0.2657 g, 5 mmol) was added, and the solution was heated at 60 °C for 10 min. Tpy-Cl 2.3 (0.2505 g, 1 mmol) was added, and the reaction was stirred at 60 °C for two days. The mixture was poured into ice water (10 mL) and 1.2 M HCl was added to reach pH 5. Filtration of the mixture isolated a beige precipitate (0.2147 g, 65% yield). 1H NMR (400 MHz, DMSO-d6) δ 8.67 (ddd, J = 4.8, 1.7, 0.9, 2H), 8.63 (m, 2H), 8.01 (td, J = 7.6, 1.8, 2H), 7.93 (s, 2H), 7.50 (m, 2H), 7.49 (m, 2H), 7.27 (m, 2H), 5.31 (br s, 1H), 4.57 (s, 2H). 13C NMR (100 MHz, DMSOd6) δ 166.8, 157.0, 154.3, 152.3, 149.2, 140.1, 137.6, 128.6, 124.7, 121.0, 120.8, 108.1, 62.4. Acid terpyridine 2.6. The procedure was adapted from a previously published method by Strekowski et al.173 Tpy-Cl 2.3 (0.0535 g, 1 mmol) and 4-mercaptobenzoic acid (0.0940 g, 3 mmol) were combined in DMF (10 mL) and placed under N2. The reaction was stirred for 2 min, then left to stand for 24 h at RT. The pink mixture was stirred and treated 57  dropwise with an ethanol/ether mixture (1:20, 40 mL) to give a white precipitate, which was collected by filtration and washed with ether (0.0281 g, 37% yield). 1H NMR (400 MHz, DMSO-d6) δ 8.78 (m, 4H), 8.33 (s, 2H), 8.24 (td, J = 1.2, 7.9, 2H), 8.07 (dt, J = 1.9, 8.4, 2H), 7.77 (dt, J = 1.9, 8.4, 2H), 7.70 (m, 2H), 5.80 (br s, 1H). 13C NMR (100 MHz, DMSO-d6) δ 166.6, 153.2, 151.9, 150.6, 147.6, 140.2, 135.1, 133.4, 131.6, 130.9, 125.8, 122.4, 119.7. IR: 1705 (C=O), 1573, 1523, 1400 (C=C, C=N), 1261 (C-O), 675 (aryl C-S). UV-vis λmax/nm (CH3CN) 232, 289. Acid complex 2.8. The procedure was modified from an established method.115 Complex 2.7 (1.6525 g, 4 mmol) was stirred under N2 for 18 h in the dark with 4hydroxyphenyl acetic acid (2.4343 g, 16 mmol) and K2CO3 (5.5292 g, 20 mmol) in 60 mL DMF. The reaction mixture was poured into 1.2 M HCl containing an equimetal molar amount (ie. equivalent to the moles of metal-containing complex used in the reaction) of NH4PF6 to give a yellow solution, which was extracted into DCM and washed twice with water. The organic extract was dried with MgSO4, filtered, and the solvent was removed under reduced pressure. The resulting product was poured into diethyl ether and left in the freezer overnight. After the ether was decanted, the brown oil was dissolved in a minimum amount of acetone, re-precipitated into ether, and placed in the freezer. The mixture was filtered, and the flask that held the mixture was air-dried to recover additional product. The product was isolated as a yellow powder (1.0793 g, 48% yield). 1H NMR (400 MHz, acetoned6) δ 7.53 (d, J = 8.6, 2H), 7.32 (d, J = 8.6, 2H), 6.85 (d, J = 7.0, 2H), 6.52 (d, J = 7.0, 2H), 5.41 (s, 5H), 3.74 (s, 2H).  13  C NMR (100 MHz, acetone-d6) δ 172.5, 152.9, 134.7, 134.0,  132.8, 121.5, 105.0, 87.9, 80.5, 77.2, 40.4. Diacid complex 2.9. The method was modified from a previously published procedure.115 Complex 2.7 (2.0373 g, 8 mmol), 4-hydroxybenzoic acid (5.3554 g, 64 mmol), 58  and K2CO3 (10.0355 g, 120 mmol) in 140 mL DMF were stirred under N2 for 18 h in darkness. The reaction mixture was poured into 1.2 M HCl containing an equimetal molar amount of NH4PF6, which was extracted into DCM and washed twice with water. The organic layer was dried with MgSO4, filtered, and the solvent was removed in vacuo. The resulting product was poured into diethyl ether and placed in the freezer overnight. The ether was decanted and the product was left to air-dry. The product was isolated as a yellow powder (0.9913 g, 33% yield). 1H NMR (400 MHz, acetone-d6) δ 8.17 (d, J = 8.7, 4H), 7.43 (d, J = 8.7, 4H), 6.59 (s, 4H), 5.43 (s, 5H). 13C NMR (100 MHz, acetone-d6) δ 166.6, 158.5, 133.2, 130.8, 129.1, 120.7, 79.6, 77.7. IR: 1697 (C=O), 1288 (C-O acid), 1232, 1128 (aryl C-O-C). UV-vis λmax/nm (CH3CN) 244. Complex 2.11. Hexanediol terpyridine 2.4 (0.1511 g, 1 mmol), acid complex 2.10 (0.2255 g, 1 mmol), DCC (0.2208 g, 2.5 mmol), and DMAP (0.1318 g, 2.5 mmol) were stirred in DCM (10 mL) under N2 for 18 h in the dark. The solvent was removed in vacuo, and the red precipitate was dissolved in a minimum amount of acetone. The solution was added dropwise to 1.2 M HCl containing an equimetal molar amount of NH4PF6 and cooled for 1 h. The precipitate was collected by filtration and washed with water. To remove unreacted acid complex 2.10, the precipitate was washed with basic water. The product was isolated as a red powder (0.5845 g, >100% yield due to DCU). 1H NMR (400 MHz, DMSOd6) δ 8.80 (m, 4H), 8.23 (t, J = 7.6, 2H), 8.11 (s, 2H), 8.10 (d, J = 8.7, 2H), 7.70 (t, J = 6.0, 2H), 7.41 (d, J = 8.7, 2H), 6.83 (d, J = 6.9, 2H), 6.53 (d, J = 6.9, 2H), 5.29 (s, 5H), 4.33 (m, 4H), 1.86 (m, 2H), 1.78 (m, 2H), 1.57-1.46 (m, 4H). 13C NMR (100 MHz, DMSO-d6) δ 167.5, 164.9, 157.1, 154.6, 152.2, 147.7, 140.0, 131.9, 130.7, 127.5, 125.6, 122.2, 120.4, 108.3, 104.0, 86.9, 79.6, 77.5, 68.5, 64.9, 28.3, 28.1, 25.2, 25.1. IR: 1710 (C=O), 1624, 1533, 1500,  59  1456 (C=C, C=N), 1357 (=C-N), 1278, 1161 (C-O-C ester). UV-vis λmax/nm (CH3CN) 246, 277, 315, 325. Complex 2.12. The synthetic method for complex 2.12 is the same as that for complex 2.11, with reagents in the following amounts: hexanediol terpyridine 2.4 (0.0930 g, 2 mmol), diacid complex 2.9 (0.1014 g, 1 mmol), DCC (0.1228 g, 4 mmol), and DMAP (0.0727 g, 4 mmol) in DCM (9 mL). The product was isolated as a pink precipitate (0.2608 g, >100% yield due to DCU and leftover diacid complex 2.9; 5:1 product to starting material). 1H NMR (400 MHz, DMSO-d6) δ 8.80 (d, J = 4.7, 4H), 8.76 (d, J = 8.0, 4H), 8.19 (t, J = 7.7, 4H), 8.10 (d, J = 8.6, 4H), 8.08 (s, 4H), 7.67 (t, J = 6.1, 4H), 7.39 (d, J = 8.6, 4H), 6.43 (s, 4H), 5.26 (s, 5H), 4.32 (q, J = 13.2, 6.6, 8H), 1.85 (m, 4H), 1.78 (m, 4H), 1.57-1.46 (m, 8H).  13  C NMR  (100 MHz, DMSO-d6) δ 167.5, 164.9, 157.8, 154.1, 152.0, 147.6, 140.8, 131.8, 128.9, 127.2, 125.7, 122.3, 119.9, 108.3, 78.4, 76.6, 68.5, 64.8, 28.3, 28.1, 25.2, 25.0. IR: 1710 (C=O), 1624, 1535, 1473, 1435 (C=C, C=N), 1346 (=C-N), 1271, 1165 (C-O-C ester). UV-vis λmax/nm (CH3CN) 245, 276, 315, 345. [Fe(hex-tpy)2][PF6]2 2.13. The procedure was obtained by optimizing the conditions from several established methods for both highest yield and purest product.133–135,147,156 Hexanediol tpy 2.4 (0.1043 g, 2 mmol) and FeCl2·4H2O (0.0313 g, 1 mmol) were dissolved in methanol (25 mL) and stirred at RT for 30 min. The purple solution was poured into water containing a ten-fold molar excess of NH4PF6, and the mixture was filtered over Celite and washed with water, ethanol, and diethyl ether. The purple precipitate was redissolved in CH3CN and the solvent was removed in vacuo to give a deep purple precipitate (0.15 g, 94% yield). 1H NMR (400 MHz, DMSO-d6) δ 8.93 (s, 4H), 8.83 (d, J = 8.0, 4H), 7.97 (td, J = 1.5, 7.8, 4H), 7.23 (d, J = 5.9, 4H), 7.17 (t, J = 7.1, 4H), 4.72 (m, 2H), 4.62 (t, J = 6.4, 4H), 3.49 (t, J = 6.0, 4H), 2.04 (pent, J = 7.0, 4H), 1.66 (pent, J = 6.9, 4H), 1.54 (m, 8H). 13C NMR (100 60  MHz, DMSO-d6) δ 167.6, 160.2, 157.9, 153.0, 138.5, 127.4, 123.7, 111.6, 70.0, 60.7, 32.6, 28.6, 25.5, 25.3. IR: 3597 (O-H), 1616, 1552, 1469, 1427 (C=C, C=N), 1365 (=C-N), 1217, 1041 (aryl C-O-CH2). UV-vis λmax/nm (CH3CN) 244, 271, 315, 365, 555. [Ni(hex-tpy)2][PF6]2 2.14. Complex 2.14 was prepared using a modified procedure from Chernyshev and co-workers, who synthesized a nickel complex with chelated terpyridine groups functionalized with 4’-hydroxymethyl-benzo-15-crown-5.156 Hexanediol tpy 2.4 (0.1702 g, 2 mmol) and nickel(II) acetate (0.0620 g, 1 mmol) were combined in methanol (42 mL) and stirred at RT for 1 h. The orange-pink solution was then poured into methanol (20 mL) containing a ten-fold molar excess of NH4PF6. The precipitate was filtered and washed with methanol and diethyl ether. The isolated product was a brown powder (0.1522 g, 60% yield). IR: 1600, 1560, 1473, 1438 (C=C, C=N), 1365 (=C-N), 1219, 1035 (aryl C-O-CH2). UV-vis λmax/nm (CH3CN) 241, 272, 311, 322, 334. MALDI-TOF-MS: m/z 901.24 (M-PF6)+. [Ru(hex-tpy)2][PF6]2 2.15. Complex 2.15 was prepared through the modification of two previously published syntheses.157,159 RuCl3·3H2O (0.2130 g, 1 mmol) was dissolved in ethanol (32 mL) and heated to reflux for 1 h to give a green solution. Tpy 2.4 (0.6860 g, 2 mmol) was added to the solution and refluxed for 18 h, after which it was filtered to remove a dark red-brown solid (presumably [Ru(hex-tpy)Cl3]). The red filtrate was treated with NH4PF6 (0.84 g, 5 mmol) in water (3 mL) dropwise and filtered; the isolated product was a red precipitate (0.1615 g, 15% yield). 1H NMR (400 MHz, DMSO-d6) δ 8.64 (d, J = 8.0, 4H), 8.39 (s, 4H), 7.96 (t, J = 7.8, 4H), 7.48 (d, J = 5.7, 4H), 7.24 (t, J = 6.5, 4H), 4.53 (m, 4H), 3.48 (t, J = 5.6, 4H), 1.99 (m, 4H), 1.62 (m, 4H), 1.52 (m, 8H). 13C NMR (100 MHz, DMSOd6) δ 164.8, 158.0, 155.7, 152.1, 137.7, 127.6, 124.2, 112.0, 69.8, 60.7, 32.5, 28.6, 25.2, 25.1. IR: 3452 (O-H), 1600, 1469, 1411 (C=C, C=N), 1365 (=C-N), 1257, 1018 (aryl C-O-CH2). 61  UV-vis λmax/nm (CH3CN) 240, 266, 303, 486. MALDI-TOF-MS: m/z 799.25 [Ru(2.4)2-H]+, 699.16 [Ru(2.4)(tpyO)]+, 681.15 [Ru(tpyO)(2.4-H2O)]+, 598.06 [Ru(tpyO)2]+. Complex 2.16. Tpy 2.5 (~0.2 g, 2 mmol) and FeCl2·4H2O (0.0568 g, 1 mmol) were stirred in methanol (30 mL) for 30 min. The reaction mixture was poured into water containing an equimetal molar amount of NH4PF6. The mixture was filtered over Celite and washed with water, ethanol, and ether. The precipitate was redissolved in CH3CN and the solvent was removed under reduced pressure to afford a purple powder (0.21 g, 70% yield). 1  H NMR (400 MHz, DMSO-d6) δ 8.91 (s, 4H), 8.78 (d, J = 8.0, 4H), 7.94 (t, J = 7.8, 4H),  7.62 (d, J = 8.7, 4H), 7.57 (d, J = 8.7, 4H), 7.36 (d, J = 5.4, 4H), 7.20 (t, J = 6.7, 4H), 4.66 (s, 4H).  13  C NMR (100 MHz, DMSO-d6) δ 166.4, 160.8, 157.5, 153.2, 152.7, 140.2, 138.6,  128.6, 127.6, 124.1, 119.8, 113.6, 62.4. IR: 3107 (O-H), 1595, 1535, 1471, 1436 (C=C, C=N), 1359 (=C-N), 1224, 1014 (aryl C-O-C), 1022 (C-O alcohol). UV-vis λmax/nm (CH3CN) 210, 243, 274, 315, 364, 557. Complex 2.17. Complex 2.17 was prepared by the same procedure as complex 2.16, combining tpy 2.6 (0.0573 g, 2 mmol) with FeCl2·4H2O (0.0155 g, 1 mmol) in methanol (10 mL). The product was isolated as a purple precipitate (0.03 g, 35% yield). 1H NMR (400 MHz, DMSO-d6) δ 9.06 (s, 4H), 8.73 (d, J = 8.0, 4H), 8.18 (t, J = 8.4, 4H), 8.03 (dt, J = 2.2, 8.4, 4H), 7.95 (td, J = 1.2, 7.8, 4H), 7.29 (d, J = 5.5, 4H), 7.19 (t, J = 6.7, 4H). 13C NMR (100 MHz, DMSO-d6) δ 166.9, 159.3, 157.1, 153.1, 149.6, 138.8, 134.6, 132.9, 132.6, 131.1, 127.8, 124.2, 122.2. IR: 1693 (C=O), 1593, 1423, 1396 (C=C, C=N), 1276 (C-O), 690 (aryl C-S). UV-vis λmax/nm (CH3CN) 220, 285, 319, 568.  62  Chapter 3 Synthesis and Characterization of Terpyridine-Based Monomers and Coordination Polymers Containing Cationic Iron Moieties 3.1 Synthesis and characterization of cationic iron-containing functionalized terpyridine monomers Acid complex 2.10 was reacted with the metal-chelated hexanediol terpyridine complexes 2.13 or 2.14 from Chapter 2 to form chloro-terminated monomers 3.1 and 3.2 for condensation polymerization, a technique implemented often in the Abd-El-Aziz research group.105–107,109,110,115,117 The appropriate metal-chelated hex-tpy complex was reacted with acid complex 2.10 in the presence of DCC and DMAP in a DMF/DCM mixture under N2 for 18 hours (Scheme 3.1). Monomer 3.1 was isolated as a purple powder, while monomer 3.2 was a yellow precipitate. These monomers could presumably be prepared by reacting ditopic ligand 2.11 containing two terminal terpyridyl groups with the appropriate metal salt, either FeCl2·4H2O for monomer 3.1 or Ni(CH3COO)2·4H2O to afford monomer 3.2, though this synthetic route was not employed in this thesis.  63  Cl  O  O  N N  OH + HO (CH2)6 O  Fe+PF6-  M2+ N  N  O (CH2)6 OH 2 PF6-  N N  2.10  2.13 M = Fe 2.14 M = Ni DCC, DMAP DMF/DCM  Cl  O Fe+PF6-  N N  O O (CH2)6 O  N  M2+ N N N  O O (CH2)6 O 2 PF6-  O  Cl Fe+PF6-  3.1 M = Fe 3.2 M = Ni  Scheme 3.1 Synthesis of monomers 3.1 and 3.2. The 1H NMR spectrum of monomer 3.1 confirms successful synthesis by the downfield shift in the methylene protons closest to the hydroxyl group of starting material 2.13, shifting from 3.62 ppm to 4.45 ppm upon esterification (Figure 3.1). This shift is a direct result of the greater deshielding effect of the ester group compared to the hydroxyl group of starting material 2.13.  64  Cl  O Fe+PF6-  f g e h N N O b c d N Fe2+ N O (CH2)6 O a 2  PF6-  N  N  3.1  O  i  k  q r u v O p s t w O Cl o n O + Fe PF6-  m  j l  x  k,l  Figure 3.1 1H NMR spectrum of monomer 3.1. Similarly, the peaks representing the aromatic protons of the former iron complex are slightly affected by the esterification reaction, with protons Hq and Hr shifting slightly downfield (~0.03 ppm) compared to the acid complex starting material due to their proximity to the deshielding ester moiety. Protons Hu and Hv shift slightly upfield, also by 0.03 ppm, while the Cp protons shift from 5.45 ppm in acid complex 2.10 to 5.42 ppm in monomer 3.1 as expected from similar esterification reactions using cationic iron moieties.108,110,111,115,117,118 65  Protons Hm, representing the methylene group bonded to the CH2 beside the ether functionality, shift downfield as well. Their assignment is confirmed by their gCOSY correlation to protons Hn, shifting from 1.62 ppm in the starting material to 1.96 ppm (Figure 3.2). These downfield shifts are due to the greater electron-withdrawing effect of the ester group as compared to the hydroxyl group of the starting material.  Cl  N  O  O  O (CH2)6 O  Fe+PF6-  Fe2+ N  N N  2 PF6-  N O m  N  O  O  n O  3.1  m  Cl Fe+PF6-  n 1.5  n  2.0 2.5 3.0 3.5 4.0  m  4.5 5.0 5.0  4.5  4.0  3.5  3.0  2.5  2.0  1.5  Figure 3.2 Portion of the gCOSY NMR spectrum of monomer 3.1 showing the 1JHH correlation between Hm and Hn.  66  The terpy yridine proto on environm ments remainn essentiallyy unchangedd compared to the startiing material,, as their electronic environments haave not channged upon thhe addition oof acid comp plex 2.10 to the hydroxy yl end groupss. The 3′,5′-pprotons (Hb) and 3,3″-prrotons (He) rremain the most m deshield ded hydrogens at 8.85 pp pm and 8.799 ppm, respeectively. Thee 4,4″-protonns (Hf) appeaar at 7.99 ppm, while the 5,5″-prottons and 6,66″-protons (H Hg and Hh) remain upfiield at 7.23 ppm and 7.49 ppm, resspectively. As A in compleex 2.13, thesse terpyridyyl shifts are ddue to i centtre, and are therefore t exppected to remain approxximately thee same chelaation to the iron(II) between the starrting materiaal and the prroduct. gHS SQC (Figuree B.1.3) andd gHMBC (F Figure 4) NMR specctra can be found f in App pendix B.1. B.1.4 Both monomeric strructures werre confirmeed by MAL LDI-TOF m mass spectrosscopy. Mono omer 3.1 dissplayed the molecular io on peak [M--PF6]+ at m//z 1891.10 (m m/z calculatted for C78H70Cl2P2F12Fee3N6O8: 189 91.160) (Figu ure 3.3).  Figure 3.3 Mass spectrum of monomeer 3.1, show wing the mollecular ion p peak [M-PF F6]+ at m/z 1891.10. 1  67  The moleecular ion peak [M-2P PF6]+ appeaars at m/z 1748.19 (m m/z calculateed for C78H70Cl2P2F12Fee2NiN6O8: 1748.196) in the mass sppectrum of m monomer 3.2 (Figure 3.4)).  Figure 3.4 Masss spectrum m of monomer 3.2, show wing the moolecular ion n peak [M-22PF6]+ at m//z 1748.19. IR spectrroscopy sup pports the formation f off monomer 3.1. The eester C=O sstretch appeaared at 171 10 cm-1, miirroring the same carbbonyl stretchh in similarrly functionnalized comp plex 2.11. Th he terpyridin ne C=C and C=N stretchhing frequenncies were shhifted to the left as expeccted upon ch helation to irron to 1616 cm c -1, 1521 ccm-1, 1500 cm m-1, and 14556 cm-1. Sim milarly, the =C-N = stretch h shifted to a slightly higher h waveenumber at 1363 cm-1, and C-O-C C ester stretcches were prresent at 127 74 cm-1 and 1165 cm-1, confirming successful eesterificationn. The terpy yridyl stretch hes of nickel(II) monomeer 3.2 matchhed closely to these valuues as well, thhough the fiinal product may have contained som me starting m material 2.144, given the weak O-H sstretch at 3325 cm-1 (Fig gure B.2.2). The UV-v vis absorban nce spectrum m of monom mer 3.1 is veery similar to that of sttarting t o f the terpyridine groups appear at 2446 nm materrial 2.13 (Figure 3.5). The π → π* transitions 68  and 268 nm, while the π → π* transition affected by the iron(II) centre remains at 315 nm. The transition at 246 nm is more intense in monomer 3.1 due to the overlap of the π → π* transitions of the terpyridine moieties and the aromatic rings of the cationic iron complex. A broad MLCT band is present at 557 nm, with small shoulder peaks at 367 nm and 506 nm, which are indicative of metal-centred d-d transitions. Similarly, the UV-vis spectrum of monomer 3.2 is almost identical to its starting material, complex 2.14, in the positioning of each absorbance band (Figure B.3.2). The ligand-centred π → π* transitions appear at 243 nm and 271 nm, with those affected by the chelation to the nickel(II) centre appearing less intensely at 311 nm and 323 nm.137,150 The band at 334 nm is most likely a result of a nickelcentred d-d transition.174 1.2  Normalized absorbance  1 0.8 0.6 0.4 0.2 complex 2.13 monomer 3.1 0 220 -0.2  320  420  520  620  720  Wavelength (nm)  Figure 3.5 Comparison of UV-vis spectra of complex 2.13 (red) and monomer 3.1 (blue). 69  3.2 Synthesis and characterization of cationic iron-containing terpyridine coordination polymers Monomer 2.12 was prepared for the purpose of coordination polymerization by reacting the terminal terpyridine groups with a metal salt. Polymer 3.3 was formed when monomer 2.12 and iron(II) chloride were combined in a minimum amount of methanol for 18 hours (Scheme 3.2). Upon addition of ammonium hexafluorophosphate and precipitation in ether, the product was afforded as a purple precipitate.  N  O N  O  O (CH2)6 O  O (CH2)6 O  Fe+PF6-  N  N  O  O  N  + FeCl2·4H2O N  2.12 MeOH O O  O  O Fe+PF6-  N N  O O (CH2)6 O  N  Fe2+ N N N  O (CH2)6 2 PF6-  n  3.3  Scheme 3.2 Synthesis of iron(II) coordination polymer 3.3. NMR spectroscopy confirms the successful coordination of terpyridine to iron(II) through the characteristic shifts of the terpyridyl hydrogen environments. The gCOSY NMR spectrum shows a correlation between the 3,3″-protons (He at 8.77 ppm) and 4,4″-protons (Hf at 7.94 ppm), which also correlate to the protons at the 5′,5″-position (Hg at 7.14 ppm) (Figure 3.6).  70  f  O  O  O  g h e N N O b cd O (CH2)6 O a N Fe2+ N  O Fe+PF6-  N  O (CH2)6  N  n  2 PF6-  3.3 e  g  f  7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 9.0  g  f  e  8.9  8.7  8.5  8.3  8.1  7.9  7.7  7.5  7.3  7.1  Figure 3.6 Portion of the gCOSY NMR spectrum of polymer 3.3, showing the 1JHH correlation between He and Hf, and Hf and Hg. The other terpyridine proton resonances are assigned from 1JCH correlations in the gHSQC NMR spectrum (Figure 3.7). Protons Hb appear as a singlet at 8.84 ppm, correlating to the carbon signal at 111.5 ppm, while protons Hh appear upfield at 7.18 ppm and correlate to carbon Ch at 153.0 ppm. In addition to the distinctive shifts of the proton signals upon chelation to iron, all resonances in the 1H NMR spectrum of polymer 3.3 are broadened, a known attribute of polymeric materials.  71  Figure 3.7 Portion of the gHSQC spectrum of polymer 3.3 showing the 1JCH correlation between carbons Ce and Ch to protons He and Hh, respectively. Nearly all other proton resonances of polymer 3.3 shift downfield from their chemical shifts in starting material 2.12 upon polymerization. For example, the methylene protons beside the ester functionality appear at 4.46 ppm, downfield from 4.32 ppm, while the methylene protons at the other end of the hexyl chain, located next to the ether linkage, shift from 4.32 ppm to 4.58 ppm. The Cp protons, however, shift upfield from 5.26 ppm in monomer 2.12 to 5.01 ppm in polymer 3.3, as is expected in polymers containing cationic iron moieties.106–111,117 Future work could determine the number of polymeric units comprising the polymer chain (ie. the value of n) using gas permeation chromatography, light scattering measurements, or viscometry, though other groups have found success utilizing end-group analysis with NMR spectroscopy.76,153 The UV-visible spectrum of polymer 3.3 is nearly identical to that of monomer 3.1 as expected, since the structure of the polymer is very similar to that of its monomer (Figure 72  B.3.3). The π → π* transitions of the terpyridine groups still appear at 246 nm and 268 nm, while the π → π* transition affected by the iron(II) centre remains at 315 nm. Shoulder peaks at 364 nm and 506 nm represent the d-d transitions localized at the iron centre, while the metal-to-ligand charge transfer band appears at 556 nm. The infrared spectrum of polymer 3.3 aided in confirming chelation of the terpyridine end groups to iron(II) due to the shift to higher wavenumbers of the C=C and C=N terpyridyl stretching frequencies in the range of 1420-1650 cm-1. Also, the =C-N stretch shifted from 1346 cm-1 in free ligand complex 2.12 to 1363 cm-1 due to the increase in double bond character upon chelation to the metal centre, which is the case for most metal-terpyridine complexes.167 Monomer 2.12 was reacted with nickel(II) acetate in methanol for 18 hours to produce nickel(II)-containing coordination polymer 3.4 as a pink-purple powder (Scheme 3.3). N  O N  O  O (CH2)6 O  O  O  O (CH2)6 O  Fe+PF6-  N  N N  + Ni(CH3COO)2·4H2O N  2.12 MeOH O O  O  O Fe+PF6-  N N  O O (CH2)6 O  N  Ni2+N  O (CH2)6  N N  2 PF6-  n  3.4  Scheme 3.3 Synthesis of coordination polymer 3.4 containing nickel(II). IR spectroscopy provides strong evidence that the polymer was successfully formed. The frequencies of the terpyridine-based stretches and the ester functionalities appear at very  73  similar wavenumbers as their corresponding peaks in complex 2.14, [Ni(hex-tpy)2][PF6]2 (Figure 3.8). 130 125 120  % Transmittance  115 110 105 100 95 90 complex 2.14 polymer 3.4  85 80 2000  1800  1600  1400 1200 Wavenumbers (cm-1)  1000  800  600  Figure 3.8 Comparison of IR spectra of complex 2.14 (red) and polymer 3.4 (blue) in the region of 600-2000 cm-1. The C=C and C=N peaks appear at 1600 cm-1, 1566 cm-1, 1477 cm-1, and 1442 cm-1, and the C-O-C stretches of the ester groups mirror those found in complex 2.14, appearing at 1276 cm-1 and 1161 cm-1. The =C-N stretching frequency shifts ~20 cm-1 to the left to 1365 cm-1 to confirm chelation to the metal centre. The most noticeable new stretch is the carbonyl stretch of the ester functionality at 1708 cm-1, shifted to a slightly lower wavenumber than in complex 2.14.  74  The ligand-centred π → π* transitions of the terpyridyl moieties and the aromatic backbone of polymer 3.4 appear at 249 nm and 265 nm in its UV-visible spectrum (Figure B.3.4). The π → π* transitions influenced by chelation to nickel appear red-shifted at 301 nm, 313 nm, and 325 nm, as is the case with metal-bound terpyridines. Monomer 3.1 was reacted with a spacer, either bisphenol A (3.5a) or hydroquinone (3.5b), for 24 hours in darkness to give coordination polymers 3.6a and 3.6b (Scheme 3.4).  Cl  O  O  N N  O (CH2)6 O  Fe+PF6-  N  Fe2+  O  O  O (CH2)6 O  N  N N  2  Cl Fe+PF6-  PF6-  3.1 3.5a R = HO +  OH  HO R OH 3.5b R = HO  OH  K2CO3 DMF  O Fe+PF6-  O O (CH2)6 O  N N N Fe2+ N N N  O O (CH2)6 O 2  PF6-  O  O R O Fe+PF6-  n  3.6a,b  Scheme 3.4 Synthesis of Fe(II) coordination polymers 3.6a (bisphenol A spacer) and 3.6b (hydroquinone spacer). The 1H NMR spectra of polymers 3.6a and 3.6b show very broad resonances. However, due to these broadened signals, assignment of most of the proton environments is very difficult. In both spectra, the Cp signal appears at approximately 5.23 ppm, shifted upfield from 5.42 ppm in monomer 3.1, confirming successful polymerization. Due to solubility issues, 13C NMR was not performed on polymer 3.6a, while the 13C NMR spectrum 75  of polymer 3.6b shows no diagnostic peaks, most likely also due to insolubility (Figure B.1.13). While NMR spectroscopy was relatively inconclusive with respect to the characterization of polymer 3.6a, the 1H and 2-D NMR spectra of polymer 3.6b at least provided information about the terpyridyl proton environments and the methylene hydrogens of the hexyl bridge beside both the ether linkage and the ester functionality. Most of these resonances shift upfield upon polymerization, suggesting the polymer has inherent stabilizing or shielding abilities upon the proton environments in each polymeric unit. This could be due to further delocalization of electron density across a wider surface area, as the addition of the hydroquinone unit should not directly have a drastic effect on the chemical shifts of the terpyridyl proton signals due to its distance from the terpyridine moiety in the molecule. This shift could also be aided by the presence of the iron centre, which would explain the signals for protons Hb and He, the only distinguishable resonances that undergo a downfield shift from their positions in monomer 3.1 (Figure 3.9).  76  f  O  O +  Fe  e b  O (CH2)6 O  PF6-  g h  N N  O  N Fe2+ N N N  x  O  O (CH2)6 O 2  O  O PF6-  +  Fe  PF6-  n  3.6b  x h  b e  9.0  g  f  8.5  8.0  7.5  7.0  6.5  6.0  5.5  5.0  4.5  4.0  3.5  3.0  2.5  2.0  1.5  1.0  0.5  Figure 3.9 1H NMR spectrum of polymer 3.6b. Given the similarity in their overall structures, the UV-visible spectra of both polymers 3.6a and 3.6b appear very similar to that of monomer 3.1, including the π → π* transitions of the terpyridine groups below 300 nm, with those affected by the iron centre at 315 nm, and the broad MLCT band around 555 nm (Figure B.3.5Figure B.3.6). The IR spectra of polymers 3.6a and 3.6b are very similar to that of starting material monomer 3.1 due to the minimal change in the overall structure. The C-O-C stretches of the newly-formed aryl ethers overlap with the frequencies of one of the C-O-C ester stretches, as  77  well as the aryl C-O-CH2 stretch, therefore preventing accurate assignment of the stretches in the 1000-1250 cm-1 region. Polymeric materials can be characterized by their thermal stability, which is of great interest in materials science and potential applications as ceramics, insulators, and numerous other uses. Thermogravimetric analysis (TGA) was performed on terpyridine-containing iron(II) coordination polymers 3.3, 3.6a, and 3.6b, as summarized in Table 3.1. The thermal degradations are similar across all three polymers, most likely due to their similar structures, and therefore polymer 3.3 is discussed as an example. Table 3.1 Summary of TGA results of iron-containing polymers 3.3, 3.6a, and 3.6b. Step 1  Step 2  Step 3  Step 4  Td (° C) (% wt)  Td (° C) (% wt)  Td (° C) (% wt)  Td (° C) (% wt)  3.3  159.81 (5.4%)  219.06 (22.3%)  388.99 (27.5%)  523.76 (3.8%)  3.6a  161.13 (7.6%)  190.30 (30.2%)  345.76 (13.7%)  425.40 (3.2%)  3.6b  101.16 (6.3%)  206.41 (31.8%)  343.47 (31.8%)  550.67 (5.4%)  Compound  The thermogram of polymer 3.3 indicates thermal degradation occurred in four steps (Figure 3.10).  78  Figure 3.10 TG GA of polymer 3.3. The weig ght loss of 22 2.3% with th hermal stabiility up to 219 °C can bbe attributed to the decoo ordination of o the cyclop pentadienyl iron(II) i moi ety, which hhas been preeviously shoown to decom mpose between 180-240 0 °C.105–112,115,117 The thiird decompoosition step at 389 °C (w weight loss of o 27.5%) is the degradaation of the aromatic a bacckbone of the polymer. T This loss occcurs at a hig gher temperaature due to o the higher bond dissocciation enerrgies of aryll bonds. Thee final weigh ht loss of 3.8 8% at 524 °C C correlates to the decom mposition off the Fe-N boonding interraction due to t its higher bond dissocciation energ gy.175–177 Alll three polym mers have finnal decompoosition temperatures sig gnificantly higher h than those obserrved in organoiron pollymers prevviously reporrted by the Abd-El-Aziiz research group106,108,,115,117 due tto the preseence of the Fe-N coord dination bon nd. The therm mal stability y of polym mers 3.3, 3..6a, and 3.66b was furrther assesseed by perfo orming diffeerential scan nning calorim metry (DSC C). This studdy provides a glass trannsition temperature (Tg) for a polym meric materiaal, which is a function oof chain flexxibility. Beloow Tg, 79  an am morphous po olymer existss in a rigid and a glassy sttate; above Tg, it transitiions to its ruubbery and pliable p statee. The easy of movemen nt of a polyymer chain determines whether thee glass transition temperrature will bee high or low w: a polymerr chain that can move arround fairly easily h a very low Tg, wh hile one that is more connfined will hhave a higheer Tg.116,178,1779 The will have for polymeer 3.3 is -211.2 °C (Figuure 3.11), w glass transition temperature t while its nickkel(II) analo ogue has a Tg of -20.1 °C. ° The Tg values v for poolymers 3.6aa and 3.6b aare -21.5 °C C and 21.9 °C, respectiively, suggesting that su uch structuraally similar ppolymer bacckbones will have comp parable glass transition temperaturees, as polym mer 3.6a coontains bisphhenol A mooieties whilee polymer 3..6b contains hydroquinone groups.  Figure 3.11 DSC C curve of polymer p 3.3 3 (Tg = -21.1 7 °C). These values aree much loweer than the glass transitioon temperatuures for otheer linear pollymers contaaining organ noiron moietties in their backbones b ppreviously ppublished by Abd-El-Aziz and  80  coworkers,106,108,115 confirming that the presence of the coordination bond lowers the Tg of the polymer while making it more thermally stable with higher decomposition temperatures.  3.3 Experimental General considerations. Protocols were identical to those reported in section 2.4, using all reagents and solvents without further purification. All reactions and complexes containing an η6-dichlorobenzene-η5-cyclopentadienyliron(II) hexafluorophosphate moiety were kept in the dark to prevent decomposition. Characterization. Protocols were identical to those reported in section 2.4, though some NMR spectral data was collected on a Bruker Avance Spectrometer (300 MHz) with a gradient field probe. Chemical shifts were referenced to residual solvent peaks and coupling constants were reported in Hz. Differential scanning calorimetry was performed on a TA Instruments DSCQ100 with a flow rate of 50 mL/min under N2, using a heat/cool/heat cycle with a heat rate of 10 °C/min and cool rate of 5 °C/min. Thermogravimetric analysis was performed on a TA Instruments TGAQ500 with a balance purge flow rate of 40 mL N2/min and a sample flow rate of 60 mL/m air. Dynamic TGA was performed, therefore the heating rate was varied. Monomer 3.1. Complex 2.13 (0.15 g, 1 mmol), acid complex 2.10 (0.1533 g, 2 mmol), DCC (0.1223 g, 4 mmol), and DMAP (0.0729 g, 4 mmol) were stirred in DMF (1.5 mL) and DCM (9 mL) under N2 for 18 h in the dark. The reaction mixture was poured into 1.2 M HCl containing an equimetal molar amount of NH4PF6, then extracted into DCM and washed twice with water. The organic extract was dried with MgSO4, filtered, and the solvent was removed in vacuo. The resulting precipitate was dissolved in a minimum amount of  81  acetone, added dropwise to diethyl ether, and placed in the freezer. The mixture was filtered and the precipitate was washed with ether to afford a deep purple powder (0.2232 g, 76% yield). 1H NMR (400 MHz, acetone-d6) δ 8.85 (s, 4H), 8.79 (m, 4H), 8.23 (d, J = 7.5, 4H), 7.99 (m, 4H), 7.49 (m, 8H), 7.23 (m, 4H), 6.88 (d, J = 5.5, 4H), 6.63 (m, 4H), 5.42 (s, 10H), 4.75 (br s, 4H), 4.45 (t, J = 5.6, 4H), 2.16 (m, 4H), 1.96 (m, 4H), 1.83 (m, 8H). 13C NMR (100 MHz, acetone-d6) δ 169.2, 165.9, 161.9, 159.3, 158.2, 154.6, 139.6, 133.2, 130.9, 129.4, 128.4, 124.8, 121.4, 112.6, 105.5, 88.2, 80.9, 78.6, 71.4, 65.9, 29.6, 29.3, 26.6, 26.5. IR: 1710 (C=O), 1616, 1521, 1500, 1456 (C=C, C=N), 1363 (=C-N), 1274, 1165 (C-O-C ester). UVvis λmax/nm (CH3CN) 246, 268, 315, 367, 506, 557. MALDI-TOF-MS: (M-PF6)+ m/z 1891.10 [M-PF6]+. Monomer 3.2. Monomer 3.2 was prepared using a similar procedure as implemented for the synthesis of monomer 3.1, combining [Ni(hex-tpy)2][PF6]2 2.14 (0.0818 g, 1 mmol), acid complex 2.10 (0.0830 g, 2 mmol), DCC (0.0655 g, 4 mmol), and DMAP (0.0386 g, 4 mmol) in DMF (1 mL) and DCM (7 mL) under N2 for 18 h in the dark. The purification steps remained identical, and the product was isolated as a yellow precipitate (0.0418 g, 25% yield). IR: 1710 (C=O), 1622, 1571, 1537, 1456 (C=C, C=N), 1367 (=C-N), 1244, 1165 (C-O-C ester). UV-vis λmax/nm (CH3CN) 243, 271, 311, 323, 334. MALDI-MS: m/z 1748.19 [M2PF6]+. Polymer 3.3. Complex 2.12 (0.1060 g, 1 mmol) and FeCl2·4H2O (0.0165 g, 1 mmol) were stirred in a minimum amount of methanol (5 mL) for 18 h. NH4PF6 (0.14 g, excess) in 5 mL MeOH was added and the reaction mixture was added dropwise to diethyl ether to produce a purple precipitate. The product was isolated via vacuum filtration and washed with diethyl ether (0.0793 g). 1H NMR (400 MHz, DMSO-d6) δ 8.85 (s, 4H), 8.77 (d, 4H), 8.24 (d, J = 8.4, 4H), 7.94 (t, 4H), 7.23 (d, J = 8.4, 4H), 7.18 (m, 4H), 7.14 (m, 4H), 6.48 (s, 4H), 5.01 82  (s, 5H), 4.58 (s, 4H), 4.46 (t, 4H), 2.08 (m, 4H), 1.88 (m, 4H), 1.76 (m, 8H). 13C NMR (100 MHz, DMSO-d6) δ 166.2, 162.6, 160.4, 159.3, 155.8, 153.0, 138.6, 132.2, 130.5, 128.0, 127.5, 123.7, 120.9, 111.5, 77.9, 76.9, 69.8, 65.2, 33.4, 27.5, 25.0, 24.5. IR: 1712 (C=O), 1604, 1502, 1471, 1427 (C=C, C=N), 1363 (=C-N), 1276, 1161 (C-O-C ester). UV-vis λmax/nm (CH3CN) 246, 268, 315, 364, 506, 556. Polymer 3.4. Ni(CH3COO)2·4H2O (0.0065 g, 1 mmol) was stirred in a minimum amount of methanol for 10 min. Complex 2.12 (0.0319 g, 1 mmol) in methanol (7 mL) was added and the mixture was stirred for 18 h. An excess of NH4PF6 in methanol (10 mL) was added to the cloudy pink solution, and the flask was put in the freezer for several hours to afford a precipitate. After filtration and washing with MeOH and diethyl ether, a fine pinkpurple precipitate was collected (0.01 g). IR: 1708 (C=O), 1600, 1566, 1477, 1442 (C=C, C=N), 1365 (=C-N), 1276, 1161 (C-O-C ester). UV-vis λmax/nm (CH3CN) 249, 265, 301, 313, 325. Polymer 3.6a. Monomer 3.1 (0.1001 g, 1 mmol), bisphenol A (0.0119 g, 1 mmol), and K2CO3 (0.073, excess) were combined in a minimum amount of DMF (3 mL) under N2, and stirred for 24 h in the dark. An excess of NH4PF6 was added to the reaction mixture, which was then added dropwise to diethyl ether and cooled for 18 h. The resulting precipitate was filtered and washed with diethyl ether to afford a pink-purple powder (0.1322 g). For NMR data, see Appendix B.1. IR: 1710 (C=O), 1598, 1537, 1504, 1471 (C=C, C=N), 1359 (=C-N). UV-vis λmax/nm (CH3CN) 241, 267, 315, 556. Polymer 3.6b. Monomer 3.1 (0.0506 g, 1 mmol), hydroquinone (0.0028 g, 1 mmol), and K2CO3 (0.0370 g, excess) were combined in DMF (2.5 mL) and stirred in the dark under N2 for 48 h. An excess of NH4PF6 was added to the flask and the reaction mixture was added dropwise to ether to product a brown/purple oil. The mixture was placed in the freezer for 83  several hours; the ether was then decanted, the oil was dissolved in a minimum amount of acetone, and the solution was added dropwise to ether. The resulting precipitate was filtered, washed with ether, and collected as a dark purple powder (0.0704 g). For NMR data, see Appendix B.1. IR: 1708 (C=O), 1612, 1546, 1469 (C=C, C=N), 1365 (=C-N). UV-vis λmax/nm (CH3CN) 245, 266, 315, 365, 506, 555.  84  Chapter 4 Conclusion The ease of substitution at the 4’-position of terpyridine was utilized to synthesize two novel terpyridines, one with a terminal phenolic group and the other functionalized with a carboxylic acid. Iron(II) complexes of these materials were then prepared by reaction of the terpyridine ligand with iron(II) chloride. The synthetic procedure of a previously published terpyridine functionalized with hexanediol was optimized for higher yield and purer product, and its chelation to Fe(II), Ru(II), and Ni(II) resulted in three novel metal complexes. The iron(II) compounds were deep purple in colour, the ruthenium(II)-complexed terpyridines were red, while the nickel(II) complexes were yellow. These metal complexes were analyzed by infrared and UV-visible spectroscopy and electrospray ionization mass spectrometry. The Fe(II) and Ru(II) complexes were characterized by nuclear magnetic resonance as well. 1H NMR spectroscopy confirmed that chelation to the metal centre caused a definitive upfield shift in the terpyridyl protons closest to the metal, while the terpyridine protons in the 3’,5’position shifted downfield significantly. UV-vis spectroscopy confirmed characteristic metalligand charge transfer bands for the ruthenium(II) complex (486 nm) and iron(II) complexes (~556 nm). A new diacid-functionalized organoiron complex was synthesized to act as a spacer in a terpyridine monomer. This diacid complex was reacted with hexanediol-functionalized terpyridine in a Steglich esterification to afford a monomer containing two terminal terpyridine units. Similarly, the hexanediol-functionalized terpyridine was also reacted with a monoacid-containing cationic iron complex, resulting in a complex that could then be polymerized through either coordination polymerization or condensation polymerization. A new organoiron-containing alcohol complex was synthesized as well.  85  Four new organoiron-containing coordination polymers were prepared: three included iron(II)-chelated terpyridine units and one contained terpyridine-nickel(II) complexation. The thermal properties of the iron(II) polymers were studied by thermogravimetric analysis and differential scanning calorimetry. The incorporation of the coordination complex into the backbone of the polymer resulted in lower glass transition temperatures but higher thermal stability than their organoiron polymer analogues free of coordination bonds. Future work should entail further variation in the functionalization of the 4’-position of terpyridine, potentially with carboxylic acids, amines, nitriles, or double or triple carboncarbon bonds, followed by reaction with organoiron-containing complexes. This would allow for an even greater breadth of possible spacers for coordination polymers, as well as adding electrochemical or photophysical properties to the resulting monomers and polymers. 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Figure A.1.5 1H NMR spectrum of acid tpy 2.6 (400 MHz, DMSO-d6). 99  Figure A.1.6  13  C NMR spectrum of acid tpy 2.6 (100 MHz, DMSO-d6).  Figure A.1.7 gCOSY NMR spectrum of acid tpy 2.6 (400 MHz, DMSO-d6).  100  Figure A.1.8 gHSQC NMR spectrum of acid tpy 2.6 (400 MHz, DMSO-d6).  Figure A.1.9 gHMBC NMR spectrum of acid tpy 2.6 (400 MHz, DMSO-d6).  101  Figure A.1.10 1H NMR spectrum of acid complex 2.8 (400 MHz, acetone-d6).  Figure A.1.11  13  C NMR spectrum of acid complex 2.8 (100 MHz, acetone-d6).  102  Figure A.1.12 gHSQC NMR spectrum of acid complex 2.8 (400 MHz, acetone-d6).  Figure A.1.13 gHMBC NMR spectrum of acid complex 2.8 (400 MHz, acetone-d6).  103  Figure A.1.14 1H NMR spectrum of diacid complex 2.9 (400 MHz, acetone-d6).  Figure A.1.15  13  C NMR spectrum of diacid complex 2.9 (100 MHz, acetone-d6).  104  Figure A.1.16 gHSQC NMR spectrum of diacid complex 2.9 (400 MHz, acetone-d6).  Figure A.1.17 gHMBC NMR spectrum of diacid complex 2.9 (400 MHz, acetone-d6).  105  Figure A.1.18 1H NMR spectrum of complex 2.11 (400 MHz, DMSO-d6).  Figure A.1.19  13  C NMR spectrum of complex 2.11 (100 MHz, DMSO-d6).  106  Figure A.1.20 gCOSY NMR spectrum of complex 2.11 (400 MHz, DMSO-d6).  Figure A.1.21 gHSQC NMR spectrum of complex 2.11 (400 MHz, DMSO-d6).  107  Figure A.1.22 gHMBC NMR spectrum of complex 2.11 (400 MHz, DMSO-d6).  Figure A.1.23  13  C NMR spectrum of complex 2.12 (100 MHz, DMSO-d6). 108  Figure A.1.24 gCOSY NMR spectrum of complex 2.12 (400 MHz, DMSO-d6).  Figure A.1.25 gHSQC NMR spectrum of complex 2.12 (400 MHz, DMSO-d6).  109  Figure A.1.26 gHMBC NMR spectrum of complex 2.12 (400 MHz, DMSO-d6).  Figure A.1.27  13  C NMR spectrum of complex 2.13 (100 MHz, DMSO-d6).  110  Figure A.1.28 gCOSY NMR spectrum of complex 2.13 (400 MHz, DMSO-d6).  Figure A.1.29 gHSQC NMR spectrum of complex 2.13 (400 MHz, DMSO-d6).  111  Figure A.1.30 gHMBC NMR spectrum of complex 2.13 (400 MHz, DMSO-d6).  Figure A.1.31  13  C NMR spectrum of complex 2.15 (100 MHz, DMSO-d6).  112  Figure A.1.32 gCOSY NMR spectrum of complex 2.15 (400 MHz, DMSO-d6).  Figure A.1.33 gHSQC NMR spectrum of complex 2.15 (400 MHz, DMSO-d6).  113  Figure A.1.34 gHMBC NMR spectrum of complex 2.15 (400 MHz, DMSO-d6).  Figure A.1.35 1H NMR spectrum of complex 2.16 (400 MHz, DMSO-d6).  114  Figure A.1.36  13  C NMR spectrum of complex 2.16 (100 MHz, DMSO-d6).  Figure A.1.37 gCOSY NMR spectrum of complex 2.16 (400 MHz, DMSO-d6).  115  Figure A.1.38 gHSQC NMR spectrum of complex 2.16 (400 MHz, DMSO-d6).  Figure A.1.39 gHMBC NMR spectrum of complex 2.16 (400 MHz, DMSO-d6).  116  Figure A.1.40 1H NMR spectrum of complex 2.17 (400 MHz, DMSO-d6).  Figure A.1.41  13  C NMR spectrum of complex 2.17 (100 MHz, DMSO-d6).  117  Figure A.1.42 gCOSY NMR spectrum of complex 2.17 (400 MHz, DMSO-d6).  Figure A.1.43 gHSQC NMR spectrum of complex 2.17 (400 MHz, DMSO-d6).  118  Figure A.1.44 gHMBC NMR spectrum of complex 2.17 (400 MHz, DMSO-d6).  119  A.2 FTIR-ATR spectra 120  % Transmittance  110 100 90 80 70 60 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  1500  1000  500  1500  1000  500  Figure A.2.1 FTIR-ATR spectrum of acid tpy. 2.6.  % Transmittance  110 100 90 80 70 60 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  Figure A.2.2 FTIR-ATR spectrum of complex 2.11.  120  120  % Transmittance  110 100 90 80 70 60 50 40 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  1500  1000  500  1500  1000  500  Figure A.2.3 FTIR-ATR spectrum of complex 2.12.  120  % Transmittance  110 100 90 80 70 60 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  Figure A.2.4 FTIR-ATR spectrum of complex 2.13.  121  120  % Transmittance  110 100 90 80 70 60 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  1500  1000  500  1500  1000  500  Figure A.2.5 FTIR-ATR spectrum of complex 2.14.  120  % Transmittance  110 100 90 80 70 60 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  Figure A.2.6 FTIR-ATR spectrum of complex 2.15.  122  120  % Transmittance  100 80 60 40 20 0 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  1500  1000  500  1500  1000  500  Figure A.2.7 FTIR-ATR spectrum of complex 2.16.  120  % Transmittance  110 100 90 80 70 60 50 40 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  Figure A.2.8 FTIR-ATR spectrum of complex 2.17.  123  A.3 UV-visible spectra  1.8  Absorbance  1.3  0.8  0.3  -0.2 220  260  300  340 380 Wavelength (nm)  420  460  Figure A.3.1 UV-visible spectrum of complex 2.9 (in CH3CN).  0.8 0.7 0.6 Absorbance  0.5 0.4 0.3 0.2 0.1 0 -0.1  200  300  400  500  600  700  800  Wavelength (nm)  Figure A.3.2 UV-visible spectrum of complex 2.15 (in CH3CN).  124  A.4 MALDI-TO OF mass speectra  F mass specttrum of com mplex 2.15. Figure A.4.1 MALDI-TOF 125  Appendix B: Spectral data for chapter 3 B.1 NMR spectra  Figure B.1.1  13  C NMR spectrum of monomer 3.1 (100 MHz, acetone-d6).  126  Figure B.1.2 gCOSY NMR spectrum of monomer 3.1 (400 MHz, acetone-d6).  Figure B.1.3 gHSQC NMR spectrum of monomer 3.1 (400 MHz, acetone-d6).  127  Figure B.1.4 gHMBC NMR spectrum of monomer 3.1 (400 MHz, acetone-d6).  128  DMSO-d6). Figure B.1.5 1H NMR specctrum of pollymer 3.3 (4400 MHz, D  Figure B.1.6  13  C NMR specctrum of po olymer 3.3 ( 100 MHz, D DMSO-d6).  129  Figure B.1.7 gCOSY NMR spectrum of polymer 3.3 (400 MHz, DMSO-d6).  Figure B.1.8 gHSQC NMR spectrum of polymer 3.3 (400 MHz, DMSO-d6).  130  Figure B.1.9 gHMBC NMR spectrum of polymer 3.3 (400 MHz, DMSO-d6).  131  Figure B.1.10 1H NMR spectrum of polymer 3.6a (400 MHz, DMSO-d6).  Figure B.1.11 gCOSY NMR spectrum of polymer 3.6a (400 NMR, DMSO-d6).  132  Figure B.1.12 gHSQC NMR spectrum of polymer 3.6a (400 MHz, DMSO-d6).  133  Figure B.1.13  13  C NMR spectrum of polymer 3.6b (100 MHz, DMSO-d6).  Figure B.1.14 gCOSY NMR spectrum of polymer 3.6b (400 MHz, DMSO-d6).  134  Figure B.1.15 gHSQC NMR spectrum of polymer 3.6b (400 MHz, DMSO-d6).  135  B.2 FTIR-ATR spectra 120  % Transmittance  100 80 60 40 20 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  1500  1000  500  Figure B.2.1 FTIR-ATR spectrum of monomer 3.1.  120  % Transmittance  110 100 90 80 70 60 50 40 4000  3500  3000  2500 2000 Wavenumber (cm-1)  1500  1000  500  Figure B.2.2 FTIR-ATR spectrum of monomer 3.2.  136  120  % Transmittance  100 80 60 40 20 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  1500  1000  500  1500  1000  500  Figure B.2.3 FTIR-ATR spectrum of polymer 3.3.  120  % Transmittance  110 100 90 80 70 60 50 40 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  Figure B.2.4 FTIR-ATR spectrum of polymer 3.6a.  137  120  % Transmittance  100 80 60 40 20 0 4000  3500  3000  2500 2000 Wavenumbers (cm-1)  1500  1000  500  Figure B.2.5 FTIR-ATR spectrum of polymer 3.6b.  138  B.3 UV-visible spectra 0.35 0.3  Absorbance  0.25 0.2 0.15 0.1 0.05 0 -0.05  200  300  400  500  600  700  800  Wavelength (nm)  Figure B.3.1 UV-visible spectrum of monomer 3.1 (in CH3CN).  4 3.5 3 Absorbance  2.5 2 1.5 1 0.5 0 -0.5  200  300  400  500  600  700  800  Wavelength (nm)  Figure B.3.2 UV-visible spectrum of monomer 3.2 (in CH3CN).  139  1 0.9 0.8 Absorbance  0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 200  300  400  500 600 Wavelength (nm)  700  800  700  800  Figure B.3.3 UV-visible spectrum of polymer 3.3 (in CH3CN).  0.4 0.35 0.3 Absorbance  0.25 0.2 0.15 0.1 0.05 0 -0.05  200  300  400  500  600  Wavelength (nm)  Figure B.3.4 UV-visible spectrum of polymer 3.4 (in CH3CN).  140  2.5  Absorbance  2 1.5 1 0.5 0 200  300  400  500 600 Wavelength (nm)  700  800  Figure B.3.5 UV-visible NMR spectrum of polymer 3.6a (in CH3CN).  0.8 0.7 0.6 Absorbance  0.5 0.4 0.3 0.2 0.1 0 -0.1  200  300  400  500  600  700  800  Wavelength (nm)  Figure B.3.6 UV-visible spectrum of polymer 3.6b (in CH3CN).  141  B.4 MALDI-TO M OF mass speectra  Cl O  Fe+PF6-  O  O (CH2)6 O  N N  N  N Fe2+ N  N  3.1  O  O (CH2)6 O  2 PF6-  O Cl  Fe+PF6-  ALDI-TOF F mass specttrum of mon nomer 3.1. Figure B.4.1 MA  142  ALDI-TOF F mass specttrum of mon nomer 3.2. Figure B.4.2 MA  143  

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