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Supramolecular self-assembly of homo- and hetero-leptic metal complexes using dipyrromethene ligands Ma, Li 2010

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SUPRAMOLECULAR SELF-ASSEMBLY OF HOMO- AND HETERO-LEPTIC METAL COMPLEXES USING DIPYRROMETHENE LIGANDS  by LI MA B.Sc., Nankai University, 2002  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY  in THE FACULTY OF GRADUATE STUDIES (Chemistry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) October 2010 © Li Ma, 2010  Abstract  Dipyrromethenes (dipyrrins) have been widely studied as important precursors for the synthesis of porphyrins for decades. More recently, bisdipyrrins, constructed through the controlled linkage of two dipyrrins, have drawn considerable attention in the field of supramolecular chemistry where supramolecular structures have exhibited potential application in the areas of gas storage and separation, catalysis and drug delivery. Bisdipyrrin metal complexes featuring double-, triple-helical or triangular structures have been previously reported by our group. The primary goal of this project was to synthesize new bisdipyrrin ligands to explore their applicability to the construction of novel homoleptic and heteroleptic metal complexes, such as circular helicates, grids, racks and ladders.  The key to the successful synthesis of the homoleptic metal complexes (circular helicates and grids) is the spacer linking two dipyrrin units. Phenyldiacetylene and carbazolediacetylene were introduced to generate dinuclear circular helicates, whereas ligands with diacetylene as the spacer formed even higher nuclear oligomers. In the case of grids, the two central pyrrole rings were fused to a ring to allow the two dipyrrin units to be parallel to each other to eliminate unwanted circular helicates. Furthermore, both hexagons and grids are formed when phenyl groups were introduced to the dipyrrin ligands, and they show channel structures in their crystalline frameworks. Studies on driving forces such as π-π stacking and F-F interactions were conducted.  ii  A series of heteroleptic anti-parallel and parallel racks were prepared. Surprisingly, zigzag racks along with the parallel racks were generated without unwanted grids when the ligand with bulky phenyl groups was introduced. During the preparation of ladders, two heteroleptic metal complexes emerged that act as both the ligand and metal ion source. A CuII rigid ladder and a ZnII flexible ladder were synthesized and characterized by X-ray diffraction analysis. Both ladders display rectangular channel structures in the solid state, which were guided by intermolecular CH/π and/or CH···O interactions.  iii  Preface  The inspiration for this project was provided by my supervisor, Prof. David Dolphin. I established the key parameters of this project through an exhaustive search of the literature and initial investigations. I designed, synthesized, purified and fully characterized the bisdipyrrin ligands which successfully resulted in the desired circular helicates, grids, racks and ladders. One paper (Ma, L.; Shin, J.-Y.; Patrick, B. O.; Dolphin, D. CrystEngComm, 2008, 10, 1539–1541) has been published from this work thus far (from Chapter Two). Six figures from the paper have been incorporated into Chapter Two. I conducted the entire research work and was the primary writer of the paper. Dr. Ji-Young Shin provided useful suggestions for the packing of the three circular helicates in the solid state and some picture-drawing techniques in the paper. Dr. Brian O. Patrick solved the crystal structures. Prof. David Dolphin offered constructive guidance and invaluable suggestions during the entire course of research and paper preparation.  iv  Table of Contents Abstract ....................................................................................................................................... ii Preface ........................................................................................................................................ iv Table of Contents ...................................................................................................................... v List of Tables ............................................................................................................................. ix List of Figures ........................................................................................................................... xi List of Schemes .................................................................................................................... xviii List of Abbreviations............................................................................................................. xix Acknowledgements .............................................................................................................. xxii  Chapter One: Introduction ............................................................................................................. 1 1.1 Supramolecular Chemistry................................................................................................... 2  1.2 Self-Assembly ...................................................................................................................... 2  1.3 Inorganic Self-Assembly...................................................................................................... 3  1.4 Circular Helicates................................................................................................................. 4  1.5 Grid-Type Metal Complexes...............................................................................................11  1.6 Rack-Type Metal Complexes ............................................................................................. 18  1.7 Ladder-Type Metal Complexes .......................................................................................... 22  1.8 Dipyrromethene (Dipyrrin) Metal Complexes................................................................... 24  1.9 Goals and Scope of the Thesis ........................................................................................... 28  v  Chapter Two: Homoleptic Circular Helicates.............................................................................. 31  2.1 Design Strategy .................................................................................................................. 32  2.2 Results and Discussion....................................................................................................... 34  2.2.1 Phenyldiacetylene Bisdipyrrin CoII Complex.............................................................. 34  2.2.1.1 Synthesis of Phenyldiacetylene Bisdipyrrin CoII Complex ..................... 34  2.2.1.2 X-Ray Analysis of Phenyldiacetylene Bisdipyrrin CoII Complex........... 36  2.2.2 Carbazolediacetylene Bisdipyrrin CoII Complex......................................................... 38  2.2.2.1 Synthesis of Carbazolediacetylene Bisdipyrrin CoII Complex................ 38  2.2.2.2 X-Ray Analysis of Carbazolediacetylene Bisdipyrrin CoII Complex...... 40  2.2.3 Diacetylene Bisdipyrrin Metal Complexes.................................................................. 43  2.2.3.1 Synthesis of Diacetylene Bisdipyrrin Metal Complexes ......................... 43  2.2.3.2 1H NMR Spectra of Diacetylene Bisdipyrrin ZnII Complexes ................ 46  2.2.3.3 X-Ray Analysis of Diacetylene Bisdipyrrin ZnII Complexes .................. 48  2.2.4 α,β-Ethyl Diacetylene Bisdipyrrin Metal Complexes.................................................. 52  2.2.4.1 Synthesis of α,β-Ethyl Diacetylene Bisdipyrrin Metal Complexes......... 53  2.2.4.2 1H NMR Spectra of α,β-Ethyl Diacetylene Bisdipyrrin ZnII Complex ... 55  2.2.4.3 X-Ray Analysis of α,β-Ethyl Diacetylene Bisdipyrrin ZnII Complex ..... 57  2.2.5 Electronic Absorption Spectra of Diacetylene Bisdipyrrin Metal Complexes ............ 59  2.3 Conclusions ........................................................................................................................ 62  Chapter Three: Homoleptic Grids and Hexagons........................................................................ 63  3.1 Design Strategy .................................................................................................................. 64  vi  3.2 Results and Discussion....................................................................................................... 66  3.2.1 Ring Fused Bisdipyrrin Metal Complexes .................................................................. 66  3.2.1.1 Synthesis of Ring Fused Bisdipyrrin Metal Complexes.......................... 66  3.2.1.2 1H NMR Spectra of Ring Fused Bisdipyrrin ZnII Complexes................. 71  3.2.1.3 X-Ray Analysis of Ring Fused Bisdipyrrin ZnII Complexes................... 76  3.2.1.3.1 X-Ray Analysis of Ring Fused Bisdipyrrin [2×2] ZnII Grids ....... 76  3.2.1.3.2 X-Ray Analysis of Ring Fused Bisdipyrrin ZnII Hexagon ........... 80  3.2.1.4 Electronic Absorption Spectra of Ring Fused Bisdipyrrin Metal Complexes ............................................................................................................................. 82  3.3 Conclusions ........................................................................................................................ 86  Chapter Four: Heteroleptic Racks and Ladders........................................................................... 87  4.1 Design Strategy .................................................................................................................. 88  4.2 Results and Discussion....................................................................................................... 90  4.2.1 Rack-Type Metal Complexes ...................................................................................... 90  4.2.1.1 Synthesis of Rack-Type Metal Complexes.............................................. 90  4.2.1.2 1H NMR Spectra of ZnII Rack-Type and Zigzag Rack-Type Complexes 95  4.2.1.3 X-Ray Analysis of ZnII Rack IV-16-3...................................................... 97  4.2.1.4 Electronic Absorption Spectra of Metal Racks and Zigzag Racks .......... 99  4.2.2 Rigid Ladder-Type Metal Complexes........................................................................ 102  4.2.2.1 Synthesis of Rigid Ladder-Type Metal Complexes............................... 103  4.2.2.2 X-Ray Analysis of CuII Rigid Ladder IV-23-L...................................... 106  vii  4.2.2.3 Electronic Absorption Spectra of Metal Rigid Ladders..........................110  4.2.3 Flexible Ladder-Type Metal Complexes ....................................................................112  4.2.3.1 Synthesis of Flexible Ladder-Type Metal Complexes............................112  4.2.3.2 1H NMR Spectra of ZnII Flexible Ladder-Type Complexes...................115  4.2.3.3 X-Ray Analysis of ZnII Flexible Ladder IV-42-L...................................117  4.2.3.4 Electronic Absorption Spectra of ZnII Flexible Ladders........................ 121  4.3 Conclusions ...................................................................................................................... 123  Chapter Five: Experimental Sections ........................................................................................ 124  5.1 General Information ......................................................................................................... 125  5.2 Experimental Procedure and Data.................................................................................... 127  5.3 Crystal Data...................................................................................................................... 198  Chapter Six: Conclusions and Future Work .............................................................................. 209  6.1 Conclusions ...................................................................................................................... 210  6.2 Future Work.......................................................................................................................211  References.................................................................................................................................. 214   viii  List of Tables  Table 2-1 Metal-to-ligand charge transfer transition band λmax(nm) for tri-, tetra- and/or pentameric metal complexes in chloroform. ............................................................................... 60  Table 3-1 Spin-allowed ligand-centered transition band λmax1(nm) and metal-to-ligand charge transfer transition band λmax2(nm) for the metal grids and/or hexagons in chloroform............... 85  Table 4-1 Metal-to-ligand charge transfer transition bands λmax (nm) for the ZnII racks in chloroform. ................................................................................................................................ 100  Table 4-2 Metal-to-ligand charge transfer transition bands λmax1 and λmax3 (nm) and spin-allowed ligand-centered transition band λmax2 (nm) for the metal racks and zigzag racks in chloroform. ................................................................................................................................................... 102  Table 4-3 Intermolecular CH/π interactions in the crystal structure of CuII rigid ladder IV-23-L. ....................................................................................................................................................110  Table 4-4 Ligand-centered transition band λmax (nm) for the ligands and metal-to-ligand charge transfer transition bands λmax (nm) for metal complexes in chloroform.....................................111  Table 4-5 Intermolecular CH/O and CH/π interactions in the crystal structure of ZnII flexible ladder IV-42-L........................................................................................................................... 120  Table 4-6 Metal-to-ligand charge transfer transition band(s) λmax (nm) for ZnII ladders in chloroform. ................................................................................................................................ 122  Table 5-1 Crystal data and structure refinement for II-7-2....................................................... 198  Table 5-2 Crystal data and structure refinement for II-13-2..................................................... 199  Table 5-3 Crystal data and structure refinement for II-25-3..................................................... 200  ix  Table 5-4 Crystal data and structure refinement for II-26-3..................................................... 201  Table 5-5 Crystal data and structure refinement for II-35-3..................................................... 202  Table 5-6 Crystal data and structure refinement for III-27-4. .................................................. 203  Table 5-7 Crystal data and structure refinement for III-33-4. .................................................. 204  Table 5-8 Crystal data and structure refinement for III-36-6. .................................................. 205  Table 5-9 Crystal data and structure refinement for IV-16-3.................................................... 206  Table 5-10 Crystal data and structure refinement for IV-23-L. ................................................ 207  Table 5-11 Crystal data and structure refinement for IV-42-L. ................................................ 208   x  List of Figures  Figure 1-1 Diagram of (a) trimeric circular helicate; (b) tetrameric circular helicate and (c) grid. ....................................................................................................................................................... 5  Figure 1-2 Synthetic route for preparation of trinuclear circular helicate I-2 (counterions omitted for clarity). ..................................................................................................................................... 6  Figure 1-3 Synthetic route for preparation of trinuclear circular helicate I-4 (counterions omitted for clarity). ..................................................................................................................................... 7  Figure 1-4 Synthetic route for preparation of trinuclear circular helicate I-6 (counterions omitted for clarity). ..................................................................................................................................... 8  Figure 1-5 Synthetic route for preparation of tetranuclear circular helicate I-8 (counterions omitted for clarity)......................................................................................................................... 9  Figure 1-6 Synthetic route for preparation of tetranuclear circular helicate I-10 (counterions omitted for clarity)......................................................................................................................... 9  Figure 1-7 Synthetic route for preparation of hexanuclear circular helicate I-12 (counterions omitted for clarity)....................................................................................................................... 10  Figure 1-8 Synthetic route for preparation of CuII [2×2] grid I-14 (counterions omitted for clarity).......................................................................................................................................... 12  Figure 1-9 Synthetic route for preparation of CuI pseudo[3×3] grid I-16 (counterions omitted for clarity).......................................................................................................................................... 13  Figure 1-10 Synthetic route for preparation of PbII [2×2] grid I-20 (counterions omitted for clarity).......................................................................................................................................... 14  xi  Figure 1-11 Synthetic route for preparation of CuII [2×2] grid I-22 (counterions omitted for clarity).......................................................................................................................................... 15  Figure 1-12 Synthetic route for preparation of AgI [3×3] grid I-24 (counterions omitted for clarity).......................................................................................................................................... 16  Figure 1-13 Synthetic route for preparation of PbII [4×4] grid I-26 (counterions omitted for clarity).......................................................................................................................................... 17  Figure 1-14 Synthetic route for preparation of CuI rack I-29 (crown ether chain and counterions omitted for clarity)....................................................................................................................... 19  Figure 1-15 Synthetic route for preparation of RuII rack I-32 (counterions omitted for clarity).20  Figure 1-16 Synthetic route for preparation of parallel RuII rack I-34 (counterions omitted for clarity).......................................................................................................................................... 21  Figure 1-17 Synthetic route for preparation of anti-parallel RuII rack I-36 (counterions omitted for clarity). ................................................................................................................................... 21  Figure 1-18 Synthetic route for preparation of heteroleptic CuI ladder I-39 (counterions omitted for clarity). ................................................................................................................................... 22  Figure 1-19 Synthetic route for preparation of heteroleptic ZnII ladder I-42 (counterions omitted for clarity). ................................................................................................................................... 23  Figure 1-20 IUPAC-recommended (left) and the commonly simplified (right) numbering systems for dipyrrins. ................................................................................................................................ 24  Figure 1-21 Bipyridine, dipyrrin ligands and their M2+ complexes............................................ 25  Figure 1-22 Bisdipyrrin ligands for preparation of ZnII or CoII double-stranded helicates. ....... 26  Figure 1-23 Synthetic route for preparation of CoIII triple-stranded helicate I-44 and mesocate xii  I-45. ............................................................................................................................................. 27  Figure 1-24 Synthetic route for preparation of ZnII trinuclear circular helicate I-47. ................ 28  Figure 2-1 Reported bisdipyrrin ligands for double- and triple-stranded helicates. ................... 32  Figure 2-2 1H NMR spectrum of dimeric CoII complex II-7-2 in CD2Cl2 (300 MHz). ............. 36  Figure 2-3 ORTEP diagram of dimeric CoII complex II-7-2 (thermal ellipsoids are scaled to the 50 % probability level): (a) top view and (b) side view. ............................................................. 37  Figure 2-4 (a) Top view of the molecular space-filled packing of II-7-2; (b) top view and (c) side view of the twin-tunnel structure of II-7-2 (reprinted with permission of the RSC). ................. 37  Figure 2-5 1H NMR spectrum of dimeric CoII complex II-13-2 in CD2Cl2 (300 MHz). ........... 40  Figure 2-6 ORTEP diagram of dimeric CoII complex II-13-2 (thermal ellipsoids are scaled to the 50 % probability level): (a) top view and (b) side view. ............................................................. 41  Figure 2-7 (a) Top view of the molecular space-filled packing of II-13-2; (b) side view and (c) top view of the single tunnel structure of II-13-2 (reprinted with permission of the RSC); (d) π-π stacking interactions between the carbazole rings of the adjacent molecules (distance = 3.32 Å) by stick representation. ..................................................................................................................... 42  Figure 2-8 1H NMR spectra (alkyl region) of ligand II-21 (top), trimeric II-25-3 (middle) and tetrameric II-25-4 (bottom) ZnII complexes in CDCl3 (300 MHz). ............................................ 47  Figure 2-9 ORTEP diagram of trimeric ZnII complex II-25-3 (thermal ellipsoids are scaled to the 50 % probability level). ............................................................................................................... 49  Figure 2-10 Stepwise packing pattern of the individual layers for II-25-3; positions of tunnels were displayed as yellow spheres in the last figure for clarity (reprinted with permission of the RSC). ........................................................................................................................................... 49  xiii  Figure 2-11 Space-filled packing of II-25-3: without (left) and with solvent molecules in space-filling (right) or stick (center) representations showing 3-fold axis disorder (reprinted with permission of the RSC)................................................................................................................ 50  Figure 2-12 ORTEP diagram of trimeric ZnII complex II-26-3 (thermal ellipsoids are scaled to the 50 % probability level). ......................................................................................................... 51  Figure 2-13 Space-filled packing of II-26-3: (a) top view; (b) and (c) side views. ................... 51  Figure 2-14 Diagram of (a) ZnII trimeric circular helicate; (b) ZnII tetrameric circular helicate and (c) ZnII grid. ................................................................................................................................. 52  Figure 2-15 1H NMR spectra (alkyl region) of ligand II-34 (top) (400 MHz), trimeric II-35-3 (middle) and tetrameric II-35-4 (bottom) ZnII complexes in CDCl3 (300 MHz)........................ 56  Figure 2-16 ORTEP diagram of trimeric ZnII complex II-35-3 (thermal ellipsoids are scaled to the 33 % probability level). ......................................................................................................... 58  Figure 2-17 Space-filled packing of II-35-3: (a) top view; (b) and (c) side views. ................... 58  Figure 2-18 Electronic absorption spectra of bisdipyrrin metal complexes in chloroform: (a) II-25, (b) II-26, (c) II-27, (d) II-28, (e) II-29, (f) II-30, (g) II-35 and (h) II-36.................................. 61  Figure 3-1 Ligands based on bipyridine introduced by Lehn and Siegel for preparation of grid-type metal complexes........................................................................................................... 64  Figure 3-2 Different conformations of the dipyrrin units in one strand linked by diacetylene (left) and a fused ring (right). ............................................................................................................... 65  Figure 3-3 1H NMR spectra (aromatic region) of ligand III-24 (top) and ZnII grid III-33-4 (bottom) in CDCl3 (400 MHz)..................................................................................................... 72  Figure 3-4 1H NMR spectra (alkyl region) of ligand III-24 (top) and ZnII grid III-33-4 (bottom) xiv  in CDCl3 (400 MHz).................................................................................................................... 72  Figure 3-5 1H NMR spectra (aromatic region) of ligand III-26 (top), ZnII grid III-36-4 (middle) and ZnII hexagon III-36-6 (bottom) in CDCl3 (400 MHz).......................................................... 74  Figure 3-6 1H NMR spectra (alkyl region) of ligand III-26 (top), ZnII grid III-36-4 (middle) and ZnII hexagon III-36-6 (bottom) in CDCl3 (400 MHz)................................................................. 75  Figure 3-7 Equilibrium between [2×2] ZnII grid III-36-4 and ZnII hexagon III-36-6 in CDCl3.76  Figure 3-8 Crystal structure of [2×2] ZnII grid III-27-4: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level) and (b) space-filled representation............................... 77  Figure 3-9 Stick-packing of [2×2] ZnII grid III-27-4: (a) top view; (b) and (c) side views. ...... 78  Figure 3-10 Crystal structure of [2×2] ZnII grid III-33-4: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level) and (b) space-filled representation............................... 79  Figure 3-11 Stick-packing of [2×2] ZnII grid III-33-4: (a) top view; (b) side view (with hexane molecules in red) and (c) π-π stacking interactions between the phenyl rings (distance = ~ 3.5 Å). ..................................................................................................................................................... 80  Figure 3-12 Crystal structure of ZnII hexagon III-36-6: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level); (b) space-filled representation and (c) stick representation with CHCl3 molecules. ................................................................................................................ 81  Figure 3-13 Stick packing of ZnII hexagon III-36-6: (a) top view; (b) side view; (c) F-F interactions between neighbouring p-fluorophenyl groups of the adjacent molecules (alkyl groups omitted for clarity) and (d) side view (with CHCl3 molecules in red/blue). ............................... 82  Figure 3-14 Electronic absorption spectra of cyclohexane bisdipyrrin metal complexes in chloroform: (a) III-27-4, III-29-4 through III-33-4 and III-35-4; (b) III-34 and (c) III-36. .... 84  xv  Figure 4-1 Rack-type CuI complexes using bipyridine ligands synthesized by Lehn (counterions omitted for clarity)....................................................................................................................... 88  Figure 4-2 Ladder-type CuI and ZnII complexes using bipyridine/terpyridine ligands reported by Lehn and Schmittel (counterions omitted for clarity).................................................................. 89  Figure 4-3 1H NMR spectra (aromatic region) of ligand III-24 (400 MHz) and IV-2 (300 MHz) (top), ZnII rack IV-16-3 (300 MHz) (middle) and zigzag ZnII rack IV-16-2 (400 MHz) (bottom) in CDCl3. ..................................................................................................................................... 96  Figure 4-4 Crystal structure of ZnII rack IV-16-3: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level) and (b) space-filled representation..................................... 98  Figure 4-5 Stick-packing of ZnII rack IV-16-3: (a) top view and (b) side view. ........................ 98  Figure 4-6 Electronic absorption spectra of rack-type ZnII complexes in chloroform: (a) IV-9-2 through IV-11-2; (b) IV-12-1 through IV-15-2; (c) IV-16 and (d) IV-17. ................................ 100  Figure 4-7 Crystal structure of CuII ladder IV-23-L: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level) and (b) space-filled representation................................... 107  Figure 4-8 Stick-packing of CuII ladder IV-23-L: (a) top view; (b) and (c) side views. .......... 108  Figure 4-9 Five types of CH/π interactions (A to E) in IV-23-L with stick representation: (a) top view and (b) side view. .............................................................................................................. 109  Figure 4-10 Electronic absorption spectra of rigid ladder-type metal complexes in chloroform: (a) ZnII ladder IV-22-L with ligand IV-18 and complex IV-20; (b) CuII ladder IV-23-L with ligand IV-19 and complex IV-21...........................................................................................................111  Figure 4-11 Partial 1H NMR spectra of ligand IV-18, ZnII ladders IV-40-L, IV-42-L and IV-43-L in CDCl3 (400 MHz). ...................................................................................................116  xvi  Figure 4-12 Crystal structure of ZnII ladder IV-42-L: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level) and (b) space-filled representation....................................118  Figure 4-13 Stick-packing of ZnII ladder IV-42-L: (a) top view; (b) and (c) side views. .........119  Figure 4-14 Two types of CH/O interactions (A and B) and two types of CH/π interactions (C and D) in IV-42-L with stick representation: (a) top view and (b) side view. ................................. 120  Figure 4-15 Electronic absorption spectra of flexible ladder-type ZnII complexes in chlororform: (a) ZnII ladder IV-40-L through IV-44-L; (b) ZnII ladder IV-42-L and IV-45-L through IV-48-L; (c) ZnII ladder IV-42-L and dimer IV-42-D. ............................................................................. 122   xvii  List of Schemes Scheme 2-1 Synthetic route for preparation of dimeric CoII complex II-7-2. ............................ 35  Scheme 2-2 Synthetic route for preparation of dimeric CoII complex II-13-2. .......................... 39  Scheme 2-3 Synthetic route for preparation of tri-, tetra- and/or pentameric metal complexes. 45  Scheme 2-4 Synthetic route for preparation of tri- and tetrameric metal complexes. ................ 54  Scheme 3-1 Synthetic route for preparation of pyrrole-2-carbaldehyde derivatives. ................. 67  Scheme 3-2 Synthetic route for preparation of [2×2] metal grids and/or hexagons. .................. 69  Scheme 4-1 Synthetic route to the ligands for preparation of rack-type metal complexes......... 91  Scheme 4-2 Synthetic route for preparation of rack-type metal complexes. .............................. 94  Scheme 4-3 Synthetic route for preparation of the heteroleptic CuII dipyrrin complex by Cohen. ................................................................................................................................................... 104  Scheme 4-4 Synthetic route for preparation of the heteroleptic ZnII and CuII bisdipyrrin complexes. ................................................................................................................................. 104  Scheme 4-5 Synthetic route for preparation of rigid ladder-type metal complexes.................. 105  Scheme 4-6 Synthetic route for preparation of pyrrole-2-carbaldehyde derivatives. ................113  Scheme 4-7 Synthetic route for preparation of flexible ladder-type ZnII complexes.................114  Scheme 6-1 Synthetic route for preparation of unsymmetric ring fused bisdipyrrin ligand and its corresponding ZnII grid.............................................................................................................. 212  Scheme 6-2 Synthetic route for preparation of heteroleptic ZnII complexes using bisdipyrrin ligand III-24 and IV-8. .............................................................................................................. 213   xviii  List of Abbreviations  Ac  acetyl  acac  acetylacetonate  anal.  analytical  Ar  aryl  Bn  benzyl  br  broad  Calcd  calculated  d  doublet  dd  doublet of doublets  DCE  dichloroethane  DCTB  2-[(2 E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]malononitrile  DME  dimethoxyethane  DMF  N,N’-dimethylformamide  DMSO  dimethyl sulfoxide  DNA  deoxyribonucleic acid  EI  electron impact  ESI  electrospray ionization  Et  ethyl  GPC  gel permeation chromatography  h  hour(s) xix  HRMS  high resolution mass spectrometry  MLCT  metal-to-ligand charge transfer  IUPAC  International Union of Pure and Applied Chemistry  LC  ligand-centered  m  meta  m  multiplet  MALDI-TOF  matrix-assisted laser desorption/ionization-time of flight  Me  methyl  min  minute(s)  MS  mass spectrometry  NIS  N-iodosuccinimde  nm  nanometer(s)  NMR  nuclear magnetic resonance  ORTEP  Oak Ridge Thermal Ellipsoid Plot  Ph  phenyl  ppm  parts per million  RSC  Royal Society of Chemistry  s  singlet  t  triplet  TFA  trifluoroacetic acid  THF  tetrahydrofuran  TLC  thin-layer chromatography xx  TMOF  trimethyl orthoformate  TMS  trimethylsilyl  UV/Vis  ultraviolet/visible  xxi  Acknowledgements  First of all, my foremost sincere gratitude goes to my supervisor, Prof. David Dolphin, for his constructive guidance, kindness, patience and invaluable support during the course of my entire research work. I would also like to thank all of the members of Dolphin’s group, past and present. My life in UBC would never been so fruitful and enjoyable without their sincere help. Special thanks go to Dr. Yan Li and Dr. Ji-Young Shin for their encouragement and help during the early stage of this project. My great appreciation goes to Ms. Qing Miao for her unreserved help and support during my entire research. Special thanks give to Mr. Andrew Tovey for his kindness and time for proofreading and precious suggestions for this thesis. I also deeply thank Dr. Lingyun Zhang, Dr. Zhan Zhang, Dr. Hua Yang and Dr. Xin Liu for their concerns and help all along the time. I truly appreciate the help from Prof. Mark MacLachlan for his time for reading the thesis and valuable advice. Thanks also go to Dr. Brian O. Patrick for X-ray crystal structures; to Dr. Yun Ling and the analysis group for Mass Spectrometry service; to Dr. Paul Xia, Dr. Maria Ezhova and Ms. Zorana Danilovic for their help on NMR analysis. Last, but not least, I would like to express my deep sense of gratitude to my parents, Mr. Ruihe Ma and Ms. Xiuling Hui, for their love, support and concern over the years.  xxii  Chapter One Introduction  1  1.1 Supramolecular Chemistry  Molecular chemistry has developed into a very powerful tool for making complex molecules and materials by covalent synthesis. Supramolecular chemistry, chemistry beyond the molecule, focuses on constructing highly-sophisticated chemical systems driven by intermolecular noncovalent interactions such as hydrogen-bonding, π-π stacking interactions, metal-ligand coordination and hydrophobic interactions.1 Through proper manipulation of these interactions, the information stored at the molecular level can be recovered, transferred, and processed at the supramolecular level through molecular recognition. Supramolecular chemistry aims at obtaining progressive control over the sophisticated structural and dynamic features of chemical systems through self-organization.  1.2 Self-Assembly  Self-assembly is the spontaneous, self-directed arrangement of components into structures without human interference. It is one of the few practical methods for constructing groups of nanostructures.2 Self-assembly is a highly-convergent synthetic strategy, which requires fewer steps to achieve final complex products from easily accessible starting materials compared to that of a conventional sequential synthetic protocol.3 There are three main stages in a self-assembly process: (i) molecular recognition for the selective binding of the fundamental components; (ii) sequential growth and ultimate binding of multiple components in the correct relative orientation; (iii) termination of the process, a built-in stop signal required to show the completion of the process.4 Self-assembly defines an algorithm through interactions between the 2  components based on the interpretation of the information stored in the structure of the precursor. It follows the algorithm to access a variety of supramolecules with extraordinary structural complexity, many of which were recently considered impossible to make.  1.3 Inorganic Self-Assembly  One of the most extensively investigated fields of self-assembly is the spontaneous formation of well-defined metallo-supramolecular architectures from specific interactions between carefully constructed covalent organic ligands and metal ions.5 These ligands should have: (i) a few binding units along the strand allowing the recognition and coordination of different metal ions, and (ii) appropriate spacers which are rigid enough to abandon the coordination of binding units within one strand to the same metal ion to form stable polynuclear complexes. Metal ions are systematically selected since they play a significant role in the assembly process: (i) a set of coordination numbers and stereochemical preferences relying on their size, charge and electronic structure; (ii) different affinities for different binding units; and (iii) explicit electronic, spectroscopic and magnetic properties exhibited in the final metal complexes.1  An enormous variety of self-assembled organic and inorganic systems have been investigated over the last two decades. Of special interest are functional multimetallic superstructures due to their potential application in the field of nanotechnology as molecular-scale sensors, switches and information storage devices.6-8 A wide range of 3  three-dimensional inorganic supramolecular architectures has recently been successfully constructed, such as double-9-11 and triple-12 stranded helicates, circular helicates,13-17 grids,18-21 racks22, 23 and ladders.24, 25  1.4 Circular Helicates  One of the most fascinating topics of metallo-supramolecular chemistry is that of helicates, and many investigations have focused on these systems.26, 27 Circular helicates, unlike their acyclic counterparts, are polynuclear complexes with a cyclic arrangement of the metal ions which are wrapped by several bridging ligands. Most of the ligands share a common structural feature: the strands have two anti-parallel bidentate or tridentate-chelating sites. Thus, for each strand, one coordinate vector is above (+) and the other is below (-) the average plane of the metal ions. However, the anti-parallel geometry of the two binding units on each strand is not rigidly locked, and the two coordinate vectors may adapt either a trans or a cis arrangement. The [2×2] grid-type geometry can be formed with tetrahedral/octahedral metal ions and the cis strands. In this case, the two coordination vectors for each strand are either above or below the mean plane of the four metal ions (Figure 1-1).  4  (a)  +  (b)  -  -  + +  +  -  -  trimeric circular helicate  +  +  -  tetrameric circular helicate  -  (c)  -  -  +  +  +  +  + -  grid  : ligand : ZnII, CoII, NiII  Figure 1-1 Diagram of (a) trimeric circular helicate; (b) tetrameric circular helicate and (c) grid.  Thummel has synthesized trinuclear circular helicate I-2, which was formed by treatment of diphenanthrolinylpyrene-bridged ligand I-1 with 1 equivalent of [Cu(MeCN)4]ClO4 in MeCN/CH2Cl2 (3/4) (Figure 1-2).13 CuI ion is of particular interest because the lability of its diimine complexes allows the formation of the most thermodynamically-stable products by ligand interchange.28 Unfortunately, only a preliminary X-ray structure could be obtained due to the poor quality of the crystal. It has D3 symmetry which indicates that all three ligands are identical and possess the same helical twist. A donut-shaped structure could be observed due to a pyrene being positioned between two phenanthrolines to generate three sandwiches. The structure is stabilized by strong π-π stacking interactions between these three aromatic rings.  5  N  N  N  N  CuI  I-1  I-2  Figure 1-2 Synthetic route for preparation of trinuclear circular helicate I-2 (counterions omitted for clarity).  Another type of ligand in which the two pyridylimine chelating sites are connected directly through the nitrogen atoms from the imine group has been introduced to the circular helicate family by Hannon. Ligand I-3 in MeOH treated with equimolar [Cu(MeCN)4]PF6 leads to complex I-4 (Figure 1-3).14 Complex I-4 was characterized as a trinuclear circular helicate by X-ray analysis. The structure is racemic owing to the existence of two enantiomers in equal amounts. The pyridylimine binding units are essentially planar (dihedral angles 1.8-6.2º), but there is a significant twisting about the central N-N bonds (dihedral angles 81-101º).  6  N N N  CuI  N  I-3  I-4  Figure 1-3 Synthetic route for preparation of trinuclear circular helicate I-4 (counterions omitted for clarity).  Hannon has also designed ligand I-5 in which two pyridylimine units are linked by sterically-hindered aryl groups. Combination of ligand I-5 and [Cu(MeCN)4]PF6 in MeOH afforded complex I-6 as a dark red solid. The solid-state structure of the single crystal obtained by diffusion of Et2O into a MeNO2 solution of I-6 shows a trinuclear circular helicate (Figure 1-4).15 There are six CH-π interactions (CH-centroid 2.9-3.0 Å) between the methyl groups of one ligand and the phenyl rings of a neighbouring ligand, which probably stabilize the structure. The side view of I-6 indicates that the triangle is not planar, but is instead slightly bent to form a bowl-shaped structure due to proper adjustment for the CH-π interactions and steric twisting of the ligands. Remarkably, a tetrameric ball-shaped array is formed by four bowl-shaped triangles I-6 through CH-π interactions. 7  N  N  CuI  N  N  I-5  I-6  Figure 1-4 Synthetic route for preparation of trinuclear circular helicate I-6 (counterions omitted for clarity).  Tetranuclear circular helicates have been accomplished by von Zelewsky. Geometrically rigid bisterpyridine ligands I-7 and I-9 in which two terpyridine units are anti-parallel to each other were treated with Zn(ClO4)2•6H2O in MeCN, followed by addition of an aqueous NH4PF6 solution to precipitate the final metal complexes I-8 and I-10 as hexafluorophosphate salts (Figure 1-5).16 Diffusion of Et2O into a MeNO2 solution of I-8 afforded an X-ray quality crystal, which shows racemic property and C2 symmetry. In order to only obtain one isomer, pinene moieties (chiral centers) were introduced into ligand I-9 to achieve chiral derivatization. Complex I-10, unlike I-8, crystallized from MeCN/MeOH/Et2O only contains one diastereomer (Figure 1-6). 8  N N N  ZnII  N N N  I-7  I-8  Figure 1-5 Synthetic route for preparation of tetranuclear circular helicate I-8 (counterions omitted for clarity).  N N N  ZnII  N N N  I-9  I-10  Figure 1-6 Synthetic route for preparation of tetranuclear circular helicate I-10 (counterions omitted for clarity). 9  The first example of a completely stereospecific hexanuclear circular helicate was also successfully represented by von Zelewsky. Ligand I-11 contains two bipyridine binding units and pinene moieties. Slow diffusion of Et2O into a MeCN solution of ligand I-11 and AgPF6 in a 1:1 molar ratio afforded complex I-12 as a hexafluorophosphate salt (Figure 1-7).17 X-ray analysis of I-12 shows that it has a crystallographic C6 axis, and the pinene groups, containing the chiral centers of the ligands, are pointed to the center of the circular structure constructing two different layers, surrounding the chiral cavity. All the xylene linkers are almost parallel (1.5º) to the C6 axis and generate the walls of the hexagon (the distance between two opposite xylene moieties is about 18.1 Å) while the terminal pyridines act as the outer shell of the hexagon. The outside diameter of the hexagon is about 30 Å and inside is about 8.4 Å. The hexagonal box is about 14 Å in depth. Helicate I-12 with the chiral cavity may become a potential candidate for the study of chiral recognition and stereoselective catalysis.  N  N  N  N  AgI  I-11  I-12  Figure 1-7 Synthetic route for preparation of hexanuclear circular helicate I-12 (counterions omitted for clarity). 10  1.5 Grid-Type Metal Complexes  In the last decade, nano-electronic devices have been of special interest, which has resulted in an enormous number of designs and explorations into molecular switches, sensors and information storage devices.7, 8, 26, 29 Suitable candidates for molecular data storage must: (i) contain two or more easily switched physicochemically-distinct states triggered by external factors such as electromagnetic fields or thermodynamic parameters and (ii) be switchable and addressable within the nanometer system. Toward this end, grid-type metal ion arrays, in which perpendicular organic ligands wrap around a set of metal ions, show several exciting features: (i) well-documented magnetic, redox and spin-state transitions; (ii) strong similarity to the binary coded matrices and cross-bar architectures used in data storage and processing technology; and (iii) potential arrangement into extended two-dimensional aggregates by solid-surface deposition.  In the design of grid-type metal ion arrays, the selection of organic ligands depends on the coordination chemistry of the metal ions. In most cases, the metal ion with tetrahedral or octahedral coordination geometries (the coordination number is 4 or 6, respectively) is usually observed. It is crucial for the successful design of the systems that the chosen ligand should possess an adequate number of chelating sites in the coordination unit to fill the coordination sphere of the metal ion.  11  Osborn has synthesized CuII [2×2] grid-type complex I-14. Combining 2 equivalents of bis(pyridyl)pyridazine ligand I-13 and 1 equivalent of [Cu(CF3SO3)2]•C6H6 in benzene afforded a brown solid (Figure 1-8).30 A single crystal was grown from a mixture of MeOH/acetone/EtOH (1/1/1), whose structure is confirmed as a rhombus. The structure of the complex cation has C2 symmetry about the Cu1-Cu2 diagonal. The distance between the pairs of ligands which are parallel to each other is 3.47 Å, which suggests the existence of strong π-π stacking interactions.  N N N  CuII  N  I-13  I-14  Figure 1-8 Synthetic route for preparation of CuII [2×2] grid I-14 (counterions omitted for clarity).  Another bidentate ligand, bisphenanthroline ligand I-15, has been introduced to construct grid-type metal complexes by Siegel.31 Treatment of a suspension of I-15 in MeCN with CuBF4 generates a red solution of grid-type metal complex I-16. Surprisingly, X-ray analysis shows that I-16 is a pseudo[3×3] grid containing a [2×2] grid as host and two additional ligands as 12  guests filling the interstitial spaces (Figure 1-9). The distance between two host biphenanthroline ligands is about 7.5 Å, which is enough to accommodate an additional ligand as an aromatic guest by intercalation. The unique supramolecular structure of I-16 also receives contributions from strong π-π stacking interactions between the ligands.  OMe  N N CuI  N N  OMe  I-15  I-16  Figure 1-9 Synthetic route for preparation of CuI pseudo[3×3] grid I-16 (counterions omitted for clarity).  Other then pairing tetrahedrally coordinated metal ions with bidentate ligands, combination of octahedrally coordinated metal ions and tridentate ligands has also been investigated for the construction of grid-type complexes by Lehn. Treatment of ligand I-17 (R=Me) with an equimolar amount of Co(OAc)2•4H2O in methanol at reflux, followed by addition of an aqueous solution of NH4SbF6 afforded the [2×2] grid-type metal complex I-18, and its structure was 13  confirmed by X-ray crystallography.18 In addition to transition metal ions, PbII ion was selected to react with ligand I-19 (R=H) in MeCN for formation of [2×2] grid-type metal complex I-20. A single crystal was grown from slow diffusion of Et2O into a solution of I-20 in MeCN, whose structure is confirmed by X-ray analysis (Figure 1-10).32 The metal ions lie almost in a plane and form a square. The bonds to the ligands in each coordination site are pushed to one part of the coordination sphere due to the existence of a stereochemically-active electron lone pair in the lead ions.33 The average M-M distance is similar in I-18 and I-20, although the Pb-N distance is much longer than Co-N due to the larger radius of the PbII ion.  N N N R  PbII  N N N  I-19 R = H  I-20  Figure 1-10 Synthetic route for preparation of PbII [2×2] grid I-20 (counterions omitted for clarity).  Brooker has successfully presented the synthesis of a new kind of [2×2] grid-type metal complex I-22 which was generated by combination of equimolar amounts of bistridentate diamide ligand I-21, Cu(BF4)2•xH2O and NEt3 in MeCN (Figure 1-11).34 X-ray analysis of I-22 14  demonstrates both deprotonated amide nitrogen atoms in each ligand are engaged in the tridentate coordination in addition to the pyridine nitrogen atoms, resulting in a distorted octahedral coordination geometry for all of the CuII ions. Remarkably, one amide proton of each ligand is left behind due to the addition of only 1 equivalent base, and then, likely, positioned in symmetrical O···H···O hydrogen bonds between the two amide oxygen atoms of each ligand strand.  N NH N  O O  CuII  N NH N  I-21  I-22  Figure 1-11 Synthetic route for preparation of CuII [2×2] grid I-22 (counterions omitted for clarity).  A much larger [3×3] grid-type metal complex has been introduced into the inorganic grid family by Lehn.35 Combination of 1 equivalent tritopic bipyridine ligand I-23 with 1.5 equivalents AgCF3SO3 in MeNO2 leads to the AgI [3×3] grid I-24 (Figure 1-12). Two sets of signals in a 2:1 ratio in 1H NMR spectrum of I-24 indicate ligand I-23 is in two different environments, which is consistent with a [3×3] grid-type structure. The  109  Ag NMR spectrum 15  displays three peaks for AgI ions positioned at the corners, the centers of the edges and the center of the [3×3] grid in 4:4:1 ratio, which further confirms the grid structure. The solid state structure of I-24 shows that the grid is a distorted rhombus, and all AgI ions are in a distorted tetrahedral geometry with the same dihedral angle of approximately 72º. The geometry of the pyridazine ring, which is not a regular hexagon, may be partially responsible for the slight bending of the ligand in I-24.  N N N AgI  N N N  I-23  I-24  Figure 1-12 Synthetic route for preparation of AgI [3×3] grid I-24 (counterions omitted for clarity).  An expanded PbII [4×4] grid I-26 has also been accomplished by Lehn.36 Treatment of polyterpyridine ligand I-25 with Pb(CF3SO3)2 in 1:2 stoichiometry results in complex I-26 which is confirmed by X-ray crystallography (Figure 1-13). Like PbII [2×2] grid I-20, the coordination geometry around PbII ions displays a hemi-directed structure.37 All eight ligands are divided into two sets of four, one of which is inner and the other is outer within the grid. 16  Thus, rather than a normal [4×4] grid, I-26 acts more as a set of four [2×2] subgrids. A strong π-π stacking interaction can be achieved due to substantial overlap between the aromatic rings in the inner ligands (centroid-centroid distance of 3.6 Å).38 All available void space in the four [2×2] subgrids is filled by triflate counterions and water molecules.  N N N N N N  PbII  N N N N N N  I-25  I-26  Figure 1-13 Synthetic route for preparation of PbII [4×4] grid I-26 (counterions omitted for clarity).  17  1.6 Rack-Type Metal Complexes  Rack-type metal complexes are multinuclear heteroleptic species possessing one polytopic ligand chelating several metal ions, each of which is also coordinated by one or more monotopic ligands.23 The polytopic molecular strands, the backbones, can be either flexible or rigid. The appropriate metal-based monotopic ligands play an important role in constructing a linear and rigid conformation in the synthesis of inorganic racks.22, 39, 40  Lehn has explored a new class of rack-type multimetallic pseudorotaxane complexes. Treatment of a mixture containing bis-bipyridine ligand I-27 and phenanthroline macrocycle I-28 with [Cu(MeCN)4]PF6 in 1:2:2 ratio in CH2Cl2/MeCN under argon afforded a dark red solid. A single crystal was obtained by slow diffusion of toluene into a nitromethane solution of complex I-29, and the structure is confirmed by X-ray crystallography (Figure 1-14).41 The two threaded phenanthroline macrocycles I-28 are in a cisoid conformation on the rigid backbone of ligand I-27. A weak π-π stacking interaction between two phenanthroline rings from I-28 can be observed in I-29. Furthermore, another set of weak π-π stacking interactions exist between the terminal phenyl group from ligand I-27 and the phenanthroline group from macrocycle I-28. Ligand I-27 are slightly bent in I-29 due to the shorter N=N bond in the pyridazyl ring which is not a regular hexagon.  18  N  N  N CuI  N N O N  O O O  I-27  O  O  I-28  I-29  Figure 1-14 Synthetic route for preparation of CuI rack I-29 (crown ether chain and counterions omitted for clarity).  Terpyridine ligands, together with bipyridine ligands, are good coordination units for the generation of stable complexes. Both high and low oxidation states of metal ions can be stabilized by coordination to the aforementioned ligands since they are good σ- and π-donors and π-acceptors.42,  43  Combination of bistridentate ligand I-30 and 2.5 equivalents of RuIII  terpyridine complex I-31 in refluxing EtOH/H2O (1:1), followed by addition of an aqueous solution of NH4PF6 afforded a green precipitate. Pure RuII complex I-32 was obtained as a green solid through successive recrystallization from MeCN/C6H6 (Figure 1-15).39 The RuIII-RuII conversion was achieved by the introduction of an electron-donating solvent. X-ray analysis indicates that the two Ru atoms are crystallographically inequivalent and are in pseudooctahedral chelation environments in I-32. The π-π stacking interactions can be expected between the phenyl group and terpyridine moieties which are stacked at van der Waals contact 19  distance in I-32.  N N N  Cl  N N  Ru  N N  Cl  EtOH/H2O  Cl  N N  I-30  I-31  I-32  Figure 1-15 Synthetic route for preparation of RuII rack I-32 (counterions omitted for clarity).  The tridentate ditopic hydrazone ligands have also been introduced as the backbones of the rack-type metal complexes by Lehn. Treatment of ligand I-33 with RuIII terpyridine complex I-31, in a molar ratio of 1:2.2, in a refluxing mixture of protic solvents which can provide electrons to reduce RuIII to RuII, led to parallel RuII rack I-34 as a green solid after recrystallization and reprecipitation (Figure 1-16). Anti-parallel rack I-36 was synthesized using the same procedure, starting with ligand I-35 (Figure 1-17).40, 44 The crystal structures show that the parallel rack I-34 exhibits a curved structure while the anti-parallel rack I-36 is totally linear. The two terpyridine ligands are crystallographically equivalent in rack I-36 while they are not in rack I-34. In contrast to I-34 in which the planes of terpyridine generate an angle of about 33º, I-36 possesses two parallel terpyridine planes which are almost perpendicular to the plane of the backbone I-35. 20  N N N N  Cl  N N  Ru  N  Cl  EtOH/H2O  Cl  N N N N  I-33  I-31  I-34  Figure 1-16 Synthetic route for preparation of parallel RuII rack I-34 (counterions omitted for clarity).  N N N N  Cl  N N  Ru  N N  Cl  EtOH/H2O  Cl  N N N  I-35  I-31  I-36  Figure 1-17 Synthetic route for preparation of anti-parallel RuII rack I-36 (counterions omitted for clarity).  21  1.7 Ladder-Type Metal Complexes  The ladder-type metal complexes, in contrast to grid-type ones, are generated through combination of heteroleptic ligands with metal ions. The rack-type metal complexes can be considered as the half-ladders. Lehn has presented the formation of the first ladder complex I-39 which is synthesized through treatment of bis-bipyridine ligand I-37 (the rail) and the bipyrimidine ligand I-38 (the rung) with [Cu(MeCN)4]PF6 in a 1:1:2 stoichiometry (Figure 1-18).24 The extreme simplicity of 1H and 13C NMR spectra of I-39 suggested the presence of a highly symmetric complex in solution. The ladder-shaped structure of I-39 was further supported by ESI-MS (electrospray ionization) measurements. However, no solid state structure of I-39 is available at this point.  N  N  Ph Cu  N N  N  N  N  N  Ph  N  Ph  N N  N  Cu Ph  N  CuI  N  Cu N  N  I-37  Ph N N  I-38  Ph N N  N N  Ph  N  Cu Ph  N  I-39  Figure 1-18 Synthetic route for preparation of heteroleptic CuI ladder I-39 (counterions omitted for clarity).  22  Schmittel has synthesized another new inorganic ladder I-42 which consists of bisphenanthroline ligand I-40, bisterpyridine ligand I-41 and ZnII ions in a 1:1:2 stoichiometry (Figure 1-19).25 Like I-39, the ladder-shaped structure of I-42 was supported by 1H and  13  C  NMR spectra and ESI-MS measurements. Due to poor quality of the crystal, only the solid state structure with a high R1 value (0.2315) could be obtained, but the structure shows that I-42 possesses a nanoscale ladder arrangement. Strong π-π stacking interactions can be observed between the terpyridine units from ligand I-41 and the aryl groups attached to 2- and 9-positions of phenanthrolines from ligand I-40. The ZnII ions were forced to adapt a heavily distorted trigonal bipyramidal geometry, instead of their usual tetrahedral geometry, due to the presence of both bidentate (I-40) and tridentate (I-41) ligands in the ZnII ladder I-42.  N N  N  N N  OH  ZnII  OH N  N  N  N  N  I-40  I-41  I-42  Figure 1-19 Synthetic route for preparation of heteroleptic ZnII ladder I-42 (counterions omitted for clarity). 23  1.8 Dipyrromethene (Dipyrrin) Metal Complexes  Dipyrrin chemistry has been fully investigated by many researchers for decades due to their application for synthesis of porphyrins. Dipyrrins possess two pyrrolic rings linked at the α- and α’-positions by a methine spacer. The two pyrrolic rings and the methine bridge are usually coplanar to achieve maximum conjugation of the π system. Both IUPAC-recommended and commonly simplified numbering systems for dipyrrins are shown in Figure 1-20.  3  4  5  6  2 1  N 10  HN 11  β  7 8 9  β α  meso  α  α'  N  HN  β' β' α'  Figure 1-20 IUPAC-recommended (left) and the commonly simplified (right) numbering systems for dipyrrins.  Bipyridines, the major binding units in the ligands introduced into Lehn’s work on supramolecular self-assembly, are neutral ligands and generate charged complexes when coordinated to metals at any oxidation state. Therefore, counterions are needed for charge balance. Unfortunately, such counterions can result in disorder in the solid state, and thus lower the chance to obtain the X-ray quality crystals for structural analysis. Furthermore, purification of these metal complexes is often very challenging through traditional separation techniques such as chromatography. Dipyrrins, on the other hand, afford mono-anionic resonance stabilized 24  ligands which readily coordinate to metal ions (M2+/M3+) to give neutral square planar, tetrahedral or octahedral complexes in which no counterions are required (Figure 1-21). Most dipyrrin metal complexes are highly crystalline and soluble in a variety of organic solvents such as methylene chloride, chloroform, THF and toluene.  Bipyridine  N  Dipyrrin  N  N  neutral ligand  N  mono-anionic ligand  M2+  M2+  2+ N  N  N M  N  N M  N  dicationic complex  N  N  neutral complex  Figure 1-21 Bipyridine, dipyrrin ligands and their M2+ complexes.  Over the past few decades, dipyrrins that can generate neutral complexes with various metal ions have been introduced as versatile ligands in the field of metallo-supramolecular chemistry. Bisdipyrrin metal complexes possessing double-,45,  46  triple-47 stranded helical  structures or triangular48 structure have been reported so far.  25  Dolphin has successfully synthesized a series of double-stranded helicates using flexible bisdipyrrin ligands in which the two dipyrrin units are linked either directly or by alkylene groups at α- and α’-positions, or by alkylene groups at β- and β’-positions (Figure 1-22). ZnII and CoII ions which favour tetrahedral coordination geometry are commonly selected to coordinate to the ligands. X-ray analysis shows that the metal complexes possess double-stranded helical geometry.45, 46  N H  N H  N  N H  N  N H  N  N  2HBr  2HBr  H N  N  CH2 n N H  N  N H 2HBr  N N H  N 2HBr n= 1, 2, 3  Figure 1-22 Bisdipyrrin ligands for preparation of ZnII or CoII double-stranded helicates.  Recently, the first triple-stranded helicates and mesocates were generated by Dolphin using a novel α-free bisdipyrrin ligand I-43 in which two dipyrrin units are linked by a methylene group at the β- and β’-positions.47 Combination of ligand I-43 and CoIII ions afforded a mixture of helicate I-44 and mesocate I-45 which can be separated by a one-meter silica gel column. The signal of the linker CH2 hydrogens is a singlet at 3.51 ppm in 1H NMR spectrum of helicate I-44  26  whereas it splits into two sets of doublets at 3.25 and 3.36 ppm in mesocate I-45. The structures of helicate and mesocate are further confirmed by X-ray analysis (Figure 1-23). Treatment of ligand I-43 with FeIII led to the same result. Surprisingly, no interconversion between helicate I-44 and mesocate I-45 can be observed even upon heating to 150˚C in solution.49, 50  N NH 2HBr  CoIII  NH N  I-43  I-44  helicate  I-45  mesocate  Figure 1-23 Synthetic route for preparation of CoIII triple-stranded helicate I-44 and mesocate I-45.  New trinuclear circular helicates have also been accomplished by Dolphin using a rigid α-free β,β’-directly linked bisdipyrrin ligand I-46.48 Treatment of ligand I-46 with ZnII or CoII ions led to formation of trimetallic complexes. X-ray analysis shows ZnII complex I-47 features a triangular structure which results in the metal centers possessing a distorted tetrahedral geometry (Figure 1-24). In each strand, one dipyrrin binding unit lies above the average plane of  27  the metal ions while the other lies below the average plane.  N NH 2HBr  ZnII  NH N  I-46  I-47  Figure 1-24 Synthetic route for preparation of ZnII trinuclear circular helicate I-47.  1.9 Goals and Scope of the Thesis  Metal-organic porous materials with molecule-sized channels have received intense scientific and technological attention because of their various potential applications in many areas, such as gas storage and separation,51-54 catalysis55, 56 and drug delivery.57, 58 Due to such critical requirements as very low temperatures and/or extremely high pressures, storage of large amounts of dihydrogen can be expensive and complex in a conventional context. The interest in storing dihydrogen, which has high energy content and is clean burning, into the cavities of porous materials for mobile fueling applications is substantial. Recently, Yaghi has reported several metal-organic frameworks (MOFs), in which the volumetric and gravimetric storage 28  densities of H2 are close to the limit of practical utility.52 In terms of catalysis, Raymond has developed a tetrahedral assembly [Ga4L6]12- as a water-soluble host which captures propargyl enammonium cations, facilitates an aza Cope rearrangement and releases the final products after hydrolysis. The catalytic reaction fits the Michaelis-Menten model of enzyme kinetics well, which indicates the host can act as an enzyme mimic in these tricky catalytic reactions under mild, aqueous conditions.55 As well, Ferey has reported that flexible porous MOFs (iron terephthalates) can be used for controlled drug delivery of Ibuprofen. Drug-matrix interactions are optimized since the MOFs can adjust their pore size to fit the dimensions of Ibuprofen, which results in an unusual zero-order kinetics drug release.58  One of the goals in this project is to create nano-sized channels in the solid state using bisdipyrrin ligands and metal ions. Very limited work has been done to study circular helicates using rigid linear meso-unsubstituted bisdipyrrin ligands and their porosities. Therefore, new ligands and multinuclear circular helicates were prepared and studied in great detail. Surprisingly, the synthesis and characterization of grid-type metal complexes using bisdipyrrin ligands is still a deserted area. In order to construct these neutral metal complexes, a variety of ring fused bisdipyrrin ligands were designed and investigated. Their interesting channel structures and corresponding driving forces in the solid state were explored in detail.  Over the past few decades, considerable interest has been drawn to the generation of multicomponent functional architectures through noncovalent self-assembly to mimic the diversity and complexity of biological systems and to study the specific biological functions.59-61 29  To the best of our knowledge, heteroleptic racks and ladders using bisdipyrrin ligands are unprecedented. Therefore, another goal of this project is to perform controlled synthesis of novel heteroleptic racks and ladders by self-sorting.29 In order to achieve this goal, the steric interaction and reactivity of the reactants were investigated for the directed synthesis. Many meso-aryl dipyrrins were synthesized based on previously reported procedures for the rack synthesis. Two new heteroleptic metal complexes as the crucial intermediates were created to generate the ladders. The exciting tunnel structures for ladders and the fascinating spectroscopic properties for both racks and ladders were studied in detail.  30  Chapter Two Homoleptic Circular Helicates  31  2.1 Design Strategy meso-Unsubstituted bisdipyrrins have been incorporated into the field of supramolecular chemistry as flexible and versatile ligands. They can be prepared as HBr salts through condensation of 2-formyl pyrrole and 2-unsubstituted pyrrole or pyrrole-2-carboxylic acid in the presence of HBr. The bisdipyrrin salts are aromatic chromophores, and more stable than their free-base counterparts. While there has been an enormous amount of study on bisdipyrrin metal complexes featuring double-45, 46, 50, 62 or triple-47 helical structures, in which the two dipyrrin units are linked either directly or by alkylene groups at the α-position, or linked by alkylene groups at the β-position (Figure 2-1), there have been relatively few studies on the bisdipyrrin metal complexes possessing multinuclear circular-helical structures.48  α N H N  α  N H N  N  2HBr  N α H  α N H  N  2HBr  β β N  HN  β  ( )n  NH  N  N  N H  β NH 2HBr  N  2HBr n = 0-6  Figure 2-1 Reported bisdipyrrin ligands for double- and triple-stranded helicates.  32  The spacers linking two dipyrrin units play an extremely important role in the design of suitable ligands for circular helicates. Combination of the previously synthesized flexible bisdipyrrins linked by alkylene groups with ZnII and CoII ions forms either the expected double helicates and even monomers if the spacer is long enough to allow the dipyrrin units to fold back  against  each  other.48  Rigid  organic  spacers,  such  as  phenyldiacetylene,  carbazolediacetylene and diacetylene, are introduced to generate rigid bisdipyrrins suitable for the construction of circular helicates.  33  2.2 Results and Discussion 2.2.1 Phenyldiacetylene Bisdipyrrin CoII Complex 2.2.1.1 Synthesis of Phenyldiacetylene Bisdipyrrin CoII Complex  The preparation of the phenyldiacetylene bisdipyrrin ligand II-6 began with the synthesis of the  spacer  II-2  which  is  the  product  of  a  Sonogashira  coupling  reaction  of  1,3-dibromo-5-t-butylbenzene and ethynyltrimethylsilane, followed by basic hydrolysis with addition  of  KOH.63  Compound  II-3  was  generated  by  iodination  of  3,5-dimethylpyrrole-2-carbaldehyde.64 A second Sonogashira coupling was conducted with II-2 and II-3 under hydrogen to give II-5 in a very low yield.65 The electron-withdrawing group attached to R was thought to decrease the electron density between the R group and iodide and thus make it easier to break the R-I bond. Apparently, the aldehyde group is not strong enough to appreciably achieve that goal. Therefore, II-4 with a more activated R-I bond was synthesized from II-3 by addition of malononitrile,66 followed by a Sonogashira coupling with II-2. Basic hydrolysis afforded II-5 in a good yield which was then condensed with 2,4-dimethylpyrrole in the presence of HBr to afford the rigid bisdipyrrin ligand II-6 as the HBr salt. Treatment of ligand II-6 with Co(OAc)2•4H2O and NaOAc generates the bisdipyrrin CoII complexes II-7 (Scheme 2-1). A non-polar fraction containing the desired metal macrocycle was first isolated by flash chromatography on silica gel with a mixed solvent system of CH2Cl2 and hexanes (3:2). The generation of the self-assembled oligomers was confirmed by MALDI-TOF mass spectrometry. The pure dimeric CoII complex II-7-2 was obtained as a slower moving fraction, after fractions of higher oligomeric CoII complexes eluted from a gel permeation 34  chromatography (GPC) column.67 The 1H NMR spectrum of the paramagnetic CoII complex II-7-2 exhibited a large range (-25 ~ 75 ppm) of signals (Figure 2-2).68  Scheme 2-1 Synthetic route for preparation of dimeric CoII complex II-7-2.  35  Figure 2-2 1H NMR spectrum of dimeric CoII complex II-7-2 in CD2Cl2 (300 MHz).  2.2.1.2 X-Ray Analysis of Phenyldiacetylene Bisdipyrrin CoII Complex  A single crystal of dimeric CoII complex II-7-2 was obtained via slow evaporation of a chloroform solution of II-7-2 and the structure was determined by X-ray diffraction analysis. Surprisingly, instead of a flat, square-shaped arrangement caused by the formation of a mesocate, II-7-2 displays a bowl-shaped arrangement with a folding angle of 128º due to the generation of a helicate. The distances between Co1 and Co2, C21 and C61 are 14.29 and 8.15 Å, respectively (Figure 2-3). The Co-N bond distances range from 1.96-1.99 Å. The dihedral angles between the mean planes of two dipyrrins coordinated to the same CoII ion are 78.8º and 71.7º, which indicates each metal center has a distorted tetrahedral geometry. The mean planes of the two terminal dipyrrins and the phenyl spacer in each ligand are tilted by 34.1º and 81.7º for strand with C21, 68.7º and 28.9º for strand with C61. The inter-layer distance between CoII ions is 18.88 Å. The three-dimensional packing structure of II-7-2 describes a twin tunnel-like structure resulting from the partial overlap, by 3.42 Å, of the 36  individual molecules (Figure 2-4), which may be explained by the absence of π-π stacking interaction between the phenyl groups due to the repulsion between the bulky t-butyl groups. Therefore, a much bigger aromatic system with less bulky substituents may be introduced as the spacer to generate larger tunnels through complete overlap of the individual molecules.  Figure 2-3 ORTEP diagram of dimeric CoII complex II-7-2 (thermal ellipsoids are scaled to the 50 % probability level): (a) top view and (b) side view.  Figure 2-4 (a) Top view of the molecular space-filled packing of II-7-2; (b) top view and (c) side view of the twin-tunnel structure of II-7-2 (reprinted with permission of the RSC). 37  2.2.2 Carbazolediacetylene Bisdipyrrin CoII Complex 2.2.2.1 Synthesis of Carbazolediacetylene Bisdipyrrin CoII Complex  Carbazole, a much bigger aromatic system, was selected as the spacer in order to form a larger tunnel in the solid state driven by π-π stacking interactions. The N atom of carbazole was protected by an ethyl group to decrease the polarity of the final metal complex for quick flash chromatography on silica gel, and improve the solubility in chloroform for crystal growth. The preparation of the carbazolediacetylene bisdipyrrin ligand II-12 began with the synthesis of the spacer II-10 which is the product of Sonogashira coupling of 9-ethyl-3,6-diiodocarbazole II-8 and ethynyltrimethylsilane, followed by hydrolysis with addition of KOH.69 A second Sonogashira coupling was employed with II-10 and II-4,65 followed by basic hydrolysis, and condensation with 2,4-dimethylpyrrole in the presence of HBr to afford the rigid bisdipyrrin ligand II-12 as the HBr salt. Combination of II-12 with Co(OAc)2•4H2O and NaOAc forms the bisdipyrrin CoII complexes II-13 (Scheme 2-2). The generation of the self-assembled oligomers collected from flash chromatography on silica gel was confirmed by MALDI-TOF mass spectrometry. The pure dimeric CoII complex II-13-2 was obtained from the same GPC column as for II-7-2.67 The 1H NMR spectrum of II-13-2 again exhibited a large range of signals (-25 ~ 75 ppm), correlating with a paramagnetic structure (Figure 2-5).68 However, no non-polar fraction was obtained from combination of either II-6 or II-12 with Zn(OAc)2•2H2O and NaOAc, which indicates no formation of the expected dimeric ZnII complexes.  38  TMS I  TMS  I  NIS  TMS Pd(PPh3)2Cl2 CuI  N  N  N II-9 90%  II-8 75%  KOH CHO  OHC  NH  HN  N II-10 99%  1) Pd(PPh3)2Cl2, CuI 2) KOH  N  + I  II-11 37% N H NC HBr  N H  CN  II-4 90% N  N NH  HN 2HBr  CoII = NaOAc  N  II-12 87%  II-13-2 22% dimeric CoII complex  Scheme 2-2 Synthetic route for preparation of dimeric CoII complex II-13-2.  39  Figure 2-5 1H NMR spectrum of dimeric CoII complex II-13-2 in CD2Cl2 (300 MHz).  2.2.2.2 X-Ray Analysis of Carbazolediacetylene Bisdipyrrin CoII Complex  A single crystal of dimeric CoII complex II-13-2 was grown from a chloroform solution of II-13-2 and the structure was determined by X-ray diffraction analysis. Complex II-13-2, like II-7-2, displays a novel bowl-shaped arrangement with a smaller folding angle of 103° due to the formation of helicate. The distances between Co1 and Co2, N9 and N10 are 16.79 and 14.75 Å, respectively (Figure 2-6). The Co-N bond distances range from 1.96-1.98 Å. The dihedral angles between the mean planes of two dipyrrins coordinated to the same CoII ion are 81.0º and 81.4º, which show each metal center has a less distorted tetrahedral geometry than that in II-7-2. The mean planes of the two terminal dipyrrins and the carbazole spacer in each ligand are tilted by 30.1º and 59.4º for the strand with N9 and 68.6º and 22.0º for the strand with N10. The inter-layer distance between CoII ions is 13.59 Å, which is much shorter than that of II-7-2. The three-dimensional packing structure of II-13-2 exhibits a much larger single tunnel  40  approximately 7.5 Å in diameter, resulting from the complete overlap of the individual molecules in the crystal. The complete overlap of the individual molecules may be driven by the strong π-π stacking interactions between the carbazole rings (distance = 3.32 Å) (Figure 2-7). Therefore, carbazole was proven to be a good spacer to successfully increase the size of the tunnel.  Figure 2-6 ORTEP diagram of dimeric CoII complex II-13-2 (thermal ellipsoids are scaled to the 50 % probability level): (a) top view and (b) side view.  41  Figure 2-7 (a) Top view of the molecular space-filled packing of II-13-2; (b) side view and (c) top view of the single tunnel structure of II-13-2 (reprinted with permission of the RSC); (d) π-π stacking interactions between the carbazole rings of the adjacent molecules (distance = 3.32 Å) by stick representation.  42  2.2.3 Diacetylene Bisdipyrrin Metal Complexes  The higher nuclearity oligomers in both II-7 and II-13 are difficult to characterize due to their extremely low yields (trace). The angular spacers linking the two terminal dipyrrins in each ligand limit the chance of generation of the higher nuclearity oligomers to some extent. Diacetylene was introduced as the linear spacer to improve the ligands for formation of higher nuclearity oligomers.  2.2.3.1 Synthesis of Diacetylene Bisdipyrrin Metal Complexes  The synthesis of the diacetylene bisdipyrrin ligands II-21–II-24 was based on the preparation of the important intermediate II-15 which started with decarboxylation of t-butyl 4-acetyl-3,5-dimethylpyrrole-2-carboxylate with TFA,70 followed by a Vilsmeier reaction.71 An oxidative coupling of II-15 afforded homo-coupled dialdehyde II-16,65 followed by treatment with 4-t-butyl-3,5-dimethylpyrrole-2-carboxylic acid or α-free pyrroles in the presence of HBr to form II-21 through II-24 as HBr salts. Combination of ligands II-21 through II-24 with Zn(OAc)2•2H2O and NaOAc generates bisdipyrrin ZnII complexes II-25 through II-28. Non-polar fractions were collected from flash chromatography on silica gel, followed by elution on a GPC column with toluene to afford three separate red fractions from each reaction. MALDI-TOF mass spectrometry shows the formation of trimeric, tetrameric and pentameric ZnII complexes in all cases except for II-28. The ZnII complexes with electron-withdrawing 43  groups appear to be more stable than their counterparts with electron-donating groups due to electron delocalization caused by inductive effects from the electron-withdrawing groups. However, treatment of ligand II-22 with either Co(OAc)2•4H2O or Ni(OAc)2•4H2O and NaOAc forms only trimeric and tetrameric bisdipyrrin metal complexes II-29 and II-30 (Scheme 2-3).  44  O  O TFA CO2tBu  N H  Pd(PPh3)2Cl2, CuI  1) DMF/POCl3 N H  2) KOH  N H  II-14 58%  CHO chloroacetone  II-15 30%  CHO  HN  NH  OHC  '  II-16 50% HBr  N  ''R1  HN  R1  NH  N  1  R  '  2HBr N H R1= t-Bu, R2= COOH R1= Et, R2= H R1= COPh, R2= H R1= CO2Me, R2= H  R2 R1= t-Bu R1= Et R1= COPh R1= CO2Me  II-17 II-18 II-19 II-20  II-21 76% II-22 80% II-23 65% II-24 64%  M= NaOAc  trimer II  1  II  1  M = Zn , R = t-Bu M = Zn , R = Et M = ZnII, R1= COPh M = ZnII, R1= CO2Me M = CoII, R1= Et M = NiII, R1= Et  tetramer  pentamer  II-25-3 19% II-26-3 17%  II-25-4 3% II-26-4 2%  II-25-5 trace II-26-5 trace  II-27-3 II-28-3 II-29-3 II-30-3  II-27-4 II-28-4 II-29-4 II-30-4  II-27-5 3%  18% 15% 8% 8%  10% 5% 4% 3%  Scheme 2-3 Synthetic route for preparation of tri-, tetra- and/or pentameric metal complexes.  45  2.2.3.2 1H NMR Spectra of Diacetylene Bisdipyrrin ZnII Complexes  The 1H NMR spectra of trimeric II-25-3 and tetrameric II-25-4 ZnII complexes dissolved in CDCl3 showed that the two NH signals, previously at δ 13.49 and 13.18 for II-21, were no longer present, which supports the formation of the ZnII complexes. Experiments indicated that coordination of II-21 with a ZnII ion to form II-25 resulted in upfield shifts for all 1H signals.46 As expected, the α and α’ methyl signals shift dramatically (~ 0.8 ppm) (Figure 2-8). X-ray analysis of II-25-3 demonstrates both the α and α’ methyl groups in one dipyrrin unit are located either above or below the mean plane of the other dipyrrin. Anisotropy results, where the methyl groups are shielded and an upfield-shifting of the signals occurs.11  46  Figure 2-8 1H NMR spectra (alkyl region) of ligand II-21 (top), trimeric II-25-3 (middle) and tetrameric II-25-4 (bottom) ZnII complexes in CDCl3 (300 MHz).  47  2.2.3.3 X-Ray Analysis of Diacetylene Bisdipyrrin ZnII Complexes  A single crystal of trimeric ZnII complex II-25-3 was obtained from a methylene chloride solution of II-25-3 and the structure was determined by X-ray diffraction analysis (Figure 2-9). Complex II-25-3 crystallizes about a three-fold axis located along the crystallographic c-axis. The structure also displays high symmetry. The distance between two ZnII ions in one molecule is 14.32 Å. The Zn-N bond distances range from 1.98-1.99 Å. The dihedral angle between the mean planes of two dipyrrins coordinated to the same ZnII ion is 79.1º, which shows each metal center has a distorted tetrahedral geometry. The dihedral angle between the mean planes of two dipyrrins in each ligand is 70.4º. The distance between the mean planes of each layer was determined to be 10.05 Å. Complex II-25-3 is almost flat, which suggests it might be a good candidate to produce nano-sized tunnels. However, II-25-3, unlike II-13-2, did not show a completely overlapped packing pattern due to the bulky terminal t-butyl groups (Figure 2-10). In fact, the molecules in complex II-25-3 adopted a unique packing pattern to minimize steric hindrance with the result being that the three-dimensional structure presents a series of honeycomb-like tunnels approximately 5.7 Å in diameter (Figure 2-11).  48  Figure 2-9 ORTEP diagram of trimeric ZnII complex II-25-3 (thermal ellipsoids are scaled to the 50 % probability level).  Figure 2-10 Stepwise packing pattern of the individual layers for II-25-3; positions of tunnels were displayed as yellow spheres in the last figure for clarity (reprinted with permission of the RSC).  49  Figure 2-11 Space-filled packing of II-25-3: without (left) and with solvent molecules in space-filling (right) or stick (center) representations showing 3-fold axis disorder (reprinted with permission of the RSC).  A single crystal of trimeric ZnII complex II-26-3 was obtained from slow diffusion of hexane into a dichloromethane solution of II-26-3 and the structure was again determined by X-ray diffraction analysis (Figure 2-12). Complex II-26-3 crystallizes with one half-molecule in the asymmetric unit, residing on a two-fold axis of rotation. The distances between two ZnII ions in one molecule are 14.05 and 13.53 Å. The Zn-N bond distances range from 1.96-2.00 Å. Between the mean planes of two dipyrrins coordinated to the same ZnII ion are dihedral angles of 79.6 and 78.2º, which show each metal center has a distorted tetrahedral geometry. The dihedral angles between the mean planes of two dipyrrins in each ligand are 73.6 and 37.0º and the inter-layer distance between ZnII ions is 16.17 Å. Unlike II-25-3, the molecules in complex II-26-3 adopted a unique packing pattern which displays a series of tunnels (approximately 7.5 Å in diameter) outside the molecule triangles (Figure 2-13).  50  Figure 2-12 ORTEP diagram of trimeric ZnII complex II-26-3 (thermal ellipsoids are scaled to the 50 % probability level).  Figure 2-13 Space-filled packing of II-26-3: (a) top view; (b) and (c) side views.  The tetrameric ZnII complexes II-25-4 and II-26-4, unlike their trimeric counterparts, are slightly soluble in CH2Cl2. Unfortunately, no X-ray structures of tetrameric ZnII complexes have been obtained so far due to unsuccessful single crystal growth, even though several solvent combinations (CHCl3/hexane, CHCl3/MeOH and CHCl3/THF) and growing methods have been investigated. In contrast to the trimeric ZnII complexes which only contain one isomer (circular  51  helicate), the tetrameric ZnII complexes may possess two isomers (circular helicate and grid) due to the two possible conformations of the two dipyrrin units linked by a diacetylene group in one strand to construct the structures. The tetrameric circular helicates contain anti-parallel dipyrrin units in all four strands, while the grids instead consist of the parallel dipyrrin units (Figure 2-14).16 (a)  +  (b)  -  -  + +  +  -  -  trimeric circular helicate  +  +  -  (c)  -  -  +  +  +  +  +  -  tetrameric circular helicate  -  grid  : ligand : ZnII  Figure 2-14 Diagram of (a) ZnII trimeric circular helicate; (b) ZnII tetrameric circular helicate and (c) ZnII grid.  2.2.4 α,β-Ethyl Diacetylene Bisdipyrrin Metal Complexes  Reaction conditions were altered for the generation of complex II-26 including addition of the ZnII ion at various times (adding in one portion to addition over an 8 h period) and variable temperatures (-10 °C to reflux in CHCl3/MeOH). The same trimer was obtained in a high yield in all cases, which implies it is both the kinetically and thermodynamically favoured product. The result of this is that optimization of the ligand is necessary to generate more of the tetramer. 52  In order to achieve this goal, we introduced ligand II-34 after replacing the methyl group with ethyl at the α- and β-positions of ligand II-22. It was thought that the repulsion between two bulkier ethyl groups at the α-position of ligand II-34 would encourage the formation of the tetramer.  2.2.4.1 Synthesis of α,β-Ethyl Diacetylene Bisdipyrrin Metal Complexes  The synthesis of the α,β-ethyl diacetylene bisdipyrrin ligand II-34 was based on the preparation of the important intermediate II-32 which began with Friedel-Crafts reaction of 2-((3,5-diethyl-1H-pyrrol-2-yl)methylene)malononitrile with acetyl chloride,70 followed by Vilsmeier reaction.71 An oxidative coupling of II-32 afforded homo-coupled dialdehyde II-33,65 followed by treatment with 3-ethyl-2,4-dimethylpyrrole and HBr to form II-34 as the HBr salt. Combination of ligand II-34 with either Zn(OAc)2•2H2O or Co(OAc)2•4H2O and NaOAc generates the dipyrrin metal complexes II-35 and II-36. A non-polar fraction was collected from flash chromatography on silica gel, followed by elution on a gel permeation chromatography (GPC) column with toluene to afford two distinct fractions in each case. MALDI-TOF mass spectrometry indicated the formation of trimer and tetramer in both cases (Scheme 2-4). As expected, the yield of tetramer from ligand II-34 increased dramatically compared to that from II-22 (2% to 13% for tetrameric ZnII complex, 4% to 12% for tetrameric CoII complex). Moreover, the introduction of ethyl groups at α-position of ligand II-34 proved to dramatically increase the solubility of the tetrameric metal complexes (i.e. highly soluble in dichloromethane). 53  Scheme 2-4 Synthetic route for preparation of tri- and tetrameric metal complexes.  54  2.2.4.2 1H NMR Spectra of α,β-Ethyl Diacetylene Bisdipyrrin ZnII Complex  The 1H NMR spectra of trimeric II-35-3 and tetrameric II-35-4 ZnII complexes dissolved in CDCl3 showed that the two NH signals, previously at δ 13.12 and 13.46 for II-34, were no longer present, which indicates the formation of the metal complexes. Experiments displayed that coordination of II-34 with ZnII ion to form II-35 led to upfield shifts for all 1H signals.46 The α-CH2 and CH3, α’-CH3 signals, similar to II-25, shift dramatically (~ 0.7-0.85 ppm) due to the same anisotropic effects mentioned before (Figure 2-15).  55  Figure 2-15 1H NMR spectra (alkyl region) of ligand II-34 (top) (400 MHz), trimeric II-35-3 (middle) and tetrameric II-35-4 (bottom) ZnII complexes in CDCl3 (300 MHz).  56  2.2.4.3 X-Ray Analysis of α,β-Ethyl Diacetylene Bisdipyrrin ZnII Complex  A single crystal of trimeric ZnII complex II-35-3 from ligand II-34 was obtained from slow diffusion of hexane into a dichloromethane solution of II-35-3 and the structure was determined by X-ray diffraction analysis (Figure 2-16). The distances between two ZnII ions in one molecule are 14.26, 14.00 and 13.93 Å. The Zn-N bond distances range from 1.91-2.00 Å, which is slightly bigger than those in II-25-3 and II-26-3. The diacetylene bridge is heavily distorted in order to accommodate the bulkier ethyl groups at the α- and β-positions of ligand II-34. Therefore, II-35-3, unlike II-25-3 and II-26-3, has no symmetry in the crystal structure. The dihedral angles between the mean planes of two dipyrrins coordinated to the same ZnII ion are 84.6, 84.3 and 82.2º, which shows each metal center has a slightly distorted tetrahedral geometry. The dihedral angles between the mean planes of two dipyrrins in each ligand are 31.7, 44.6 and 38.3º. The inter-layer distance between ZnII ions is 15.08 Å. In contrast to II-26-3, the molecules in complex II-35-3 adopted a partially overlapped packing pattern which leads to a series of smaller tunnels (approximately 3.5 Å in diameter) outside the molecule triangles (Figure 2-17).  57  Figure 2-16 ORTEP diagram of trimeric ZnII complex II-35-3 (thermal ellipsoids are scaled to the 33 % probability level).  Figure 2-17 Space-filled packing of II-35-3: (a) top view; (b) and (c) side views.  58  2.2.5 Electronic Absorption Spectra of Diacetylene Bisdipyrrin Metal Complexes  The diacetylene bisdipyrrin ZnII complexes, II-25-26, II-28 and II-35, are dichroic red/green solids upon crystallization, but generate red solutions when dissolved in chloroform. Complex II-27 is a dichroic purple/green solid upon crystallization, but forms a reddish purple solution when dissolved in chloroform. The CoII complexes, II-29 and II-36, are dichroic purple/green solids upon crystallization, but form purple solutions when dissolved in chloroform. However, the NiII complex II-30 is a dark brown solid, and generates a dark brown solution. Complexes II-25-30 and II-35-36 were analyzed by electronic absorption spectroscopy (Figure 2-18). As expected, the strongest absorption of all complexes in chloroform is a sharp band (λmax) resulting from a metal-to-ligand charge transfer transition (Table 2-1). An ascending trend of λmax can be observed in the ZnII complexes (II-26 and II-35), which may be caused by hyperconjugation effects through replacing methyl groups with ethyl groups.72 A large bathochromic shift (~10 nm) occurs with a phenylketone group (II-27) on the β” position of the ligand instead of an alkyl group (II-26) owing to the larger π-conjugated systems extended by the electron-withdrawing group.73 However, an ester group seems less effective, only causing a relatively small bathochromic shift (~2 nm). The absorption wavelengths (λmax) of the tri- and tetrameric metal complexes are either the same or marginally shifted (1 to 3 nm) in each case, consistent with similar coordination environments for the metal ions and no major difference between the two distinct π-conjugated systems of the tri- and tetrameric metal complexes. In short, the optical properties of the metal complexes depend much more on the ligand spacer and the metal ions than the substituents present on the pyrrole groups. 59  Table 2-1 Metal-to-ligand charge transfer transition band λmax(nm) for tri-, tetra- and/or pentameric metal complexes in chloroform.  λmax (nm)/logε Complex Trimer  Tetramer  Pentamer  II-25  544/5.81  544/5.93  —  II-26  542/5.82  542/5.90  —  II-27  554/5.68  553/5.82  553/5.92  II-28  545/5.77  544/5.84  —  II-29  540/5.54  541/5.73  —  II-30  580/5.40  582/5.50  —  II-35  546/5.82  543/5.93  —  II-36  544/5.66  541/5.74  —  60  Figure 2-18 Electronic absorption spectra of bisdipyrrin metal complexes in chloroform: (a) II-25, (b) II-26, (c) II-27, (d) II-28, (e) II-29, (f) II-30, (g) II-35 and (h) II-36. 61  2.3 Conclusions  The bisdipyrrin ligands with diacetylene as their rigid and linear spacer have been prepared, and readily react with different metal ions (ZnII, CoII and NiII) to afford tri-, tetra- and/or pentameric metal complexes. The trimeric ZnII complexes contain a trinuclear circular-helical structure confirmed by X-ray analysis. The three-dimensional packing of the crystal structures display a variety of tunnel-like structures with different sizes and shapes. No single crystals of the tetrameric ZnII complexes were obtained owing to the unsuccessful separation of the two possible isomers (circular helicate and grid). Therefore, the structures of tetrameric ZnII complexes are still unsolved. By contrast, the grid-type metal complexes with locked parallel dipyrrin units contain only one isomer, which easily solved the purification problem. The next chapter will focus on the grid-type metal complexes.  62  Chapter Three Homoleptic Grids and Hexagons  63  3.1 Design Strategy  meso-Unsubstituted bisdipyrrin salts prepared through condensation have been widely studied as ligands for formation of metal complexes featuring double-45, 46 or triple-47 helical structures. I have already synthesized and characterized the trimeric ZnII circular helicates using rigid linear diacetylene bisdipyrrin ligands in this study. However, no single crystals of the tetrameric ZnII complexes were obtained due to the unsuccessful separation of the two possible isomers (circular helicate and grid). Therefore, the structures of tetrameric ZnII circular helicate and grid are still unsolved. By contrast, the grid-type metal complexes with locked parallel dipyrrin units contain only one isomer, which easily solved the purification obstacle. As far as we are aware, no grid-type metal complexes based on bisdipyrrin ligands have been reported thus far. Inspired by the work of Lehn and Siegel on grid-type metal complexes using bipyridine ligands (Figure 3-1),19, 31, 35 porous bisdipyrrin metal grids as potential candidates for gas storage, catalysis and drug delivery were thoroughly investigated.  Ar N  N  N  N  N N  N  N  N N  N  N  N  N Ar  Figure 3-1 Ligands based on bipyridine introduced by Lehn and Siegel for preparation of grid-type metal complexes. 64  The spacer linking two dipyrrin units is the key to the design of appropriate ligands for grid-type metal complexes. Flexible spacers, such as methylene and ethylene, favour the generation of double- or triple-stranded helicates, as expected. The linear rigid spacer, diacetylene, prefers the formation of circular helicates due to the more stable anti-parallel conformation of the dipyrrin units in each strand. A spacer which can lock the two dipyrrin units in the parallel position is required for the suitable candidates. In order to achieve that goal, a fused ring system was introduced. The two central pyrrole rings from the dipyrrin units are fused on the cyclohexane ring to generate a linear bisdipyrrin ligand with the two dipyrrin units parallel to each other (Figure 3-2).  N  HN NH  N  N  HN  NH  2HBr  2HBr  anti-parallel  parallel  N  Figure 3-2 Different conformations of the dipyrrin units in one strand linked by diacetylene (left) and a fused ring (right).  65  3.2 Results and Discussion 3.2.1 Ring Fused Bisdipyrrin Metal Complexes 3.2.1.1 Synthesis of Ring Fused Bisdipyrrin Metal Complexes  The preparation of the ring fused bisdipyrrins began with the synthesis of various pyrrole-2-carbaldehyde derivatives (Scheme 3-1). The simplest pyrrole-2-carbaldehyde III-1 was selected as a starting point. In order to investigate the substituent effects on the pyrrole rings for the generation of metal grids, several pyrrole-2-carbaldehyde derivatives were prepared. III-2 is the product of Friedel-Crafts reaction of III-1 and 2-chloro-2-methylbutane in DCE with anhydrous aluminum chloride as the catalyst.74 III-6 was obtained by Suzuki reaction of III-3, 3,5-dimethylphenylboronic acid and Pd(PPh3)2Cl2 in DME in the presence of a solution of K2CO3 in water, followed by basic hydrolysis.75 The same procedure was used to synthesize III-7, starting from 4-nonylphenylboronic acid. The same Suzuki reaction condition was performed to generate III-9 from III-8. Basic hydrolysis of III-9, followed by addition of acetic acid afforded III-12 as a grey precipitate. Treatment of dried III-12 with TFA , followed by addition of TMOF, gave III-15 as a yellow solid in a high yield.76 III-16 and -17 were obtained using the same synthetic route.  66  Cl  CHO  N H  CHO  N H  AlCl3  III-1  III-2 67% I  N Ts III-3  R CHO  RB(OH)2 N Ts  Pd(PPh3)2Cl2  R=  R=  C9H19  R CHO  N H III-8  N H  CHO  III-4 73%  III-6 87%  III-5 78%  III-7 92%  RB(OH)2 I  KOH  1) TFA  1) KOH  CO2Et Pd(PPh3)2Cl2  R  N H  CO2Et  2) HOAc  R  N H  CO2H 2) TMOF  R  N H  CHO  R=  III-9 92%  III-12 78%  III-15 90%  R=  III-10 70%  III-13 76%  III-16 80%  III-11 87%  III-14 92%  III-17 92%  R=  F  Scheme 3-1 Synthetic route for preparation of pyrrole-2-carbaldehyde derivatives.  67  The important starting material III-18 for the ring fused bisdipyrrins was synthesized based on a previously reported procedure.77 Hydrogenation of III-18 in the presence of palladium on activated carbon as the catalyst,46 followed by treatment with pyrrole-2-carbaldehyde derivatives III-1 and -2, III-6 and -7, III-15-17 and HBr formed ligands III-20 through III-26 as their HBr salts. Combination of ligands III-20 through III-26 with Zn(OAc)2•2H2O and NaOAc generates the bisdipyrrin ZnII complexes III-27, III-29, III-31-34 and III-36. Non-polar fractions were collected from flash chromatography on silica gel eluting with CH2Cl2, followed by elution through a gel permeation chromatography (GPC) column with toluene to afford two separated dark green fractions for both III-34 and III-36, one dark green fraction for III-33, and only one dark blue fraction for the others except for III-27. Compound III-27 could not be purified by a GPC column due to very poor solubility in toluene. MALDI-TOF mass spectrometry of III-34 and III-36 both show the formation of a tetranuclear [2×2] ZnII grid and a hexameric ZnII hexagon, but only the peak for [2×2] ZnII grid was obtained for the remaining compounds. Furthermore, treatment of ligand III-20, III-21 and III-25 with either Co(OAc)2•4H2O or Ni(OAc)2•4H2O and NaOAc forms only tetranuclear [2×2] metal grids (Scheme 3-2).  68  O  O +  CO2CH2Ph  N  Zn NaOAc  CO2CH2Ph  PhH2CO2C  NH  HN  H2 Pd/C  PhHN  O  III-18 36% HOOC  ' HBr  +  NH  HN  R3  N H  R2  ''  R2  N  CHO  HN  NH  N  ' R3  R3 2HBr  III-19 1  R1  R  R1  R2  COOH  1  2  R = R = R3 = H,  III-1  III-20 80%  R1 = R3 = H, R2 = i Pentyl  III-2  III-21 86%  R1 =  , R2 = R3 = H  III-6  III-22 84%  R1 =  C9H19 , R2 = R3 = H  III-7  III-23 36%  R1 = Et, R2 = Me, R3 =  III-15  III-24 87%  R1 = Et, R2 = Me, R3 =  III-16  III-25 81%  III-17  III-26 90%  R1 = Et, R2 = Me, R3 =  F  M= NaOAc  M = ZnII, R1 = R2 = R3 = H,  III-27-4 19%  M = CoII, R1 = R2 = R3 = H,  III-28-4 21%  II  1  3  2  M = Zn , R = R = H, R = i Pentyl  III-29-4 17%  M = NiII, R1 = R3 = H, R2 = i Pentyl  III-30-4 5%  M = ZnII, R1 =  , R2 = R3 = H  III-31-4 11%  M = ZnII, R1 =  C9H19 , R2 = R3 = H  III-32-4 13%  M = ZnII, R1 = Et, R2 = Me, R3 =  III-33-4 7%  M = ZnII, R1 = Et, R2 = Me, R3 =  III-34-4 10%  M = CoII, R1 = Et, R2 = Me, R3 =  III-35-4 11%  M = ZnII, R1 = Et, R2 = Me, R3 =  F  III-36-4 9%  III-34-6 1%  III-36-6 2%  Scheme 3-2 Synthetic route for preparation of [2×2] metal grids and/or hexagons. 69  Ligand III-20 with no substituents on the terminal pyrrole rings was insoluble in most common solvents (CH2Cl2, CHCl3, MeOH, toluene and DMSO) or a solvent mixture due to its large flat structure. Therefore, an alkyl or phenyl group was introduced to the β”- or β’-position of the terminal pyrrole rings of ligands III-21 and -22 which rendered them readily soluble in mixed solvent systems (CH2Cl2/MeOH or CHCl3/MeOH). The solubility of ligands III-23 through III-26 increased dramatically (in CHCl3), when the phenyl ring with a long chain was attached to the β’-position or the phenyl ring was attached to the α’-position of the terminal pyrrole rings.  To a dark purple suspension of ligand III-20 in CHCl3/MeOH (2/1) was added Zn(OAc)2•2H2O and NaOAc. The suspension rapidly changed to a fluorescent blue solution. The [2×2] ZnII grid III-27-4 was obtained in a moderate yield (~20%) after collection from flash chromatography on silica gel eluting with chloroform. Complex III-27-4 is very soluble in chloroform. No further purification (GPC) could be conducted due to its poor solubility in toluene. By contrast, the [2×2] metal grids based on ligands III-21-26 are all soluble in toluene, which allows further purification using a GPC column. The yields of [2×2] ZnII grids based on ligands III-25 and III-26 are much lower (9-10%) than that of III-27-4 due to the inter-ligand crowding caused by the phenyl groups at the α’-position of the terminal pyrrole rings. Moreover, the much bulkier 3,5-dimethylphenyl groups in ligand III-24 make the yield even lower (7%). The substituents at the β’’-or β’-position of the terminal pyrrole rings show very little effect on the yields of the corresponding [2×2] metal grids.  70  3.2.1.2 1H NMR Spectra of Ring Fused Bisdipyrrin ZnII Complexes  The 1H NMR spectra of [2×2] ZnII grid III-33-4 dissolved in CDCl3 showed the two NH signals, previously at δ 14.27 and 12.52 for III-24, were no longer present, which supports the formation of the ZnII grid. Experiments indicated that coordination of III-24 with ZnII ions to form III-33-4 resulted in upfield shifts for all 1H signals. The meso-H and para-H signals shift about 0.5 ppm while the ortho-H signals, remarkably, shift upfield about 1 ppm due to strong anisotropic effects (Figure 3-3). The α-CH2 signals, as expected, shift dramatically (~ 1.3 ppm) owing to the same anisotropic effects (Figure 3-4). X-ray analysis of III-33-4 demonstrates both the α-CH2 group and ortho-H in one dipyrrin unit are located either above or below the mean plane of the other dipyrrin unit in one coordination center leading to strong anisotropic effects, which may explain the dramatic upfield-shifting observed.  71  Figure 3-3 1H NMR spectra (aromatic region) of ligand III-24 (top) and ZnII grid III-33-4 (bottom) in CDCl3 (400 MHz)  Figure 3-4 1H NMR spectra (alkyl region) of ligand III-24 (top) and ZnII grid III-33-4 (bottom) in CDCl3 (400 MHz). 72  The 1H NMR spectra of [2×2] ZnII grid III-36-4 and ZnII hexagon III-36-6 dissolved in CDCl3, like that of III-33-4, indicated that the two NH signals, previously at δ 14.25 and 12.61 for III-26, were no longer present, which indicates the generation of the ZnII grid and hexagon. Experiments showed that coordination of III-26 with ZnII ions to form III-36-4 and III-36-6 led to upfield shifts for all 1H signals. The meso-H and meta-H signals in III-36-4 shift upfield 0.51 ppm and 0.61 ppm, respectively. However, in III-36-6, both signals showed even further upfield shifts (0.53 ppm and 0.65 ppm, respectively), compared to those in III-36-4. By contrast, the ortho-H signal shifts the opposite way. The signal in III-36-6 showed a little smaller upfield shift than that in III-36-4 (0.97 ppm to 1.04 ppm). Theoretically, the ortho-H in one dipyrrin unit in III-36-4 should lie right above or below the center of the mean plane of another dipyrrin unit from the same coordination center due to the two orthogonal dipyrrin planes, while that in III-36-6 slides away from the center slightly owing to the dihedral angel (60º) between the two mean planes of the dipyrrin units in one coordination site. Therefore, the former was thought to suffer much stronger anisotropic effects than the latter, which may be a suitable explanation for the uncommon upfield shift observed (Figure 3-5). The opposite phenomena occur for the α-CH2 and β-CH3 signals, both of which in III-36-6 displayed a slightly larger upfield shift than those in III-36-4 (1.50 and 0.34 ppm for III-36-6, 1.33 and 0.17 ppm for III-36-4, respectively) (Figure 3-6).  73  Figure 3-5 1H NMR spectra (aromatic region) of ligand III-26 (top), ZnII grid III-36-4 (middle) and ZnII hexagon III-36-6 (bottom) in CDCl3 (400 MHz).  74  Figure 3-6 1H NMR spectra (alkyl region) of ligand III-26 (top), ZnII grid III-36-4 (middle) and ZnII hexagon III-36-6 (bottom) in CDCl3 (400 MHz).  75  Surprisingly, the 1H NMR spectrum of freshly prepared ZnII hexagon III-36-6 in CDCl3, unlike that of III-34-6 (no fluoride substituent), showed two full sets of signals which can be assigned to grid III-36-4 and hexagon III-36-6. There appears to be an equilibrium between the tetrameric grid and hexameric hexagon (Figure 3-7), though no such equilibrium occurred in the 1  H NMR spectrum of [2×2] ZnII grid III-36-4 in CDCl3.  Figure 3-7 Equilibrium between [2×2] ZnII grid III-36-4 and ZnII hexagon III-36-6 in CDCl3.  3.2.1.3 X-Ray Analysis of Ring Fused Bisdipyrrin ZnII Complexes 3.2.1.3.1 X-Ray Analysis of Ring Fused Bisdipyrrin [2×2] ZnII Grids  A single crystal of III-27-4 was grown from slow diffusion of hexane into a CHCl3 solution and the structure was investigated by X-ray diffraction analysis (Figure 3-8). Complex III-27-4 is indeed a slightly distorted square-like grid consisting of four ZnII ions and four ligand III-20 components. Ligand III-20 units are aligned alternately above and below the mean plane through the four ZnII ions.28 The square-shaped III-27-4 also results from the absence of the substituents at the α’-position of ligand III-20. The distances between two adjacent ZnII ions in  76  one molecule are 8.24, 8.18, 8.37 and 8.22 Å. The distances between two diagonal ZnII ions in one molecule are 11.47 and 11.73 Å. The Zn-N bond lengths range from 1.96-2.01 Å which are close to those in ZnII double helicates.46 The dihedral angles between the mean planes of two dipyrrins coordinated to the same ZnII ion are 87.8, 85.3, 85.1 and 87.5º, which indicates each metal center has a slightly distorted tetrahedral geometry owing to the sufficient flexibility of the cyclohexadiene ring. This flexibility allows each ligand to adjust to the stereochemical requirements of the Zn4 unit and causes each metal center to only slightly deviate from perfect tetrahedral coordination geometry. The dihedral angles between the planes of two dipyrrins within each ligand are 10.1, 27.5, 20.8 and 24.0º due to the same aforementioned reason. The three-dimensional packing structure of III-27-4 exhibits no tunnel-like structure due to the partial overlap of the individual molecules (Figure 3-9).  Figure 3-8 Crystal structure of [2×2] ZnII grid III-27-4: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level) and (b) space-filled representation.  77  Figure 3-9 Stick-packing of [2×2] ZnII grid III-27-4: (a) top view; (b) and (c) side views.  A single crystal of [2×2] ZnII grid III-33-4 was grown from slow diffusion of hexane into a CHCl3 solution and the structure was determined by X-ray diffraction analysis (Figure 3-10). Complex III-33-4 crystallizes with one half-molecule related to another by rotation about a two-fold axis. Unlike III-27-4, complex III-33-4 is not a square but is instead a rhombus. The distance between two adjacent ZnII ions in one molecule is 8.24 Å. The distances between two diagonal ZnII ions in one molecule are 9.19 and 13.80 Å. The Zn-N bond lengths lie in the range of 1.98-2.00 Å which are close to those in III-27-4. The dihedral angles between the mean planes of two dipyrrins coordinated to the same ZnII ion are 68.6 and 71.1º, which indicates each metal center has a much more distorted tetrahedral geometry than that in III-27-4. It was thought that the interligand crowding caused by the bulky 3,5-dimethylphenyl groups at the α’-position of ligand III-24 would push the two dipyrrin planes away from each other at the corner with Zn1, and consequently push them towards each other at the adjacent corner with Zn2 owing to the same interligand crowding between the two parallel ligands. As a result, 78  complex III-33-4 forms a rhombus, which may also be supported by the strong π-π stacking interaction between the phenyl ring in one ligand and the dipyrrin plane in another at each corner (distance = ~ 3.5 Å).38,  78, 79  The dihedral angles between the phenyl rings and the  dipyrrin planes attached to them at the corner with Zn2 are much smaller than those at the corner with Zn1 (46.7 and 56.8º for the former, 55.8 and 61.3º for the latter), which result from the larger steric hindrance at the former to force the two phenyl rings to rotate away from each other. The dihedral angles between the mean planes of two dipyrrins in each ligand are 9.2, 15.0, 8.5 and 14.3º due to the slight flexibility of the cyclohexadiene ring. The three-dimensional packing structure of III-33-4, unlike III-27-4, displays a single rhombus-like tunnel (10.5 and 6.0 Å in diameter), resulting from the complete overlap of the individual molecules in the crystal. The complete overlap of the individual molecules may be driven by the strong π-π stacking interactions between the phenyl rings from the adjacent molecules (distance = ~ 3.5 Å) and by the highly-ordered arrangement of the hexane molecules co-crystallized in the lattice (Figure 3-11).  Figure 3-10 Crystal structure of [2×2] ZnII grid III-33-4: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level) and (b) space-filled representation. 79  Figure 3-11 Stick-packing of [2×2] ZnII grid III-33-4: (a) top view; (b) side view (with hexane molecules in red) and (c) π-π stacking interactions between the phenyl rings (distance = ~ 3.5 Å).  3.2.1.3.2 X-Ray Analysis of Ring Fused Bisdipyrrin ZnII Hexagon  A single crystal of ZnII hexagon III-36-6 was obtained from slow diffusion of hexane into a chloroform solution of III-36-6 and the structure was confirmed by X-ray diffraction analysis (Figure 3-12). Complex III-36-6 is a true hexagon with an S6 axis perpendicular to the mean plane through the six ZnII ions. The ligand units are divided into two sets, one of which lies above and the other below the mean plane through the six ZnII ions. The distance between two adjacent ZnII ions in one molecule is 8.16 Å. The distance between two diagonal ZnII ions in one molecule is 16.10 Å. The Zn-N bond lengths range from 1.97-1.99 Å which are close to those in III-33-4. The dihedral angle between the mean planes of two dipyrrins coordinated to the same ZnII ion is about 73.7º which is much larger than those in III-33-4. This also indicates each metal center has a distorted tetrahedral geometry. The dihedral angle between the mean planes of two dipyrrins in each ligand is ca. 19.3º. The complete overlap of the individual molecules in 80  the crystal leads to a single hexagonal channel (12.8 Å in diameter) in the three-dimensional packing structure of III-36-6. Strong F-F interactions between the neighbouring p-fluorophenyl groups of the adjacent molecules are observed with an F-F distance of ca. 3.5 Å, which may play a significant role in the generation of the channel in the solid state.80, 81 Each hexagon captures six chloroform molecules, which are located alternately above and below the mean plane through the six ZnII ions to provide an overall arrangement with three above and three below (Figure 3-13).  Figure 3-12 Crystal structure of ZnII hexagon III-36-6: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level); (b) space-filled representation and (c) stick representation with CHCl3 molecules.  81  Figure 3-13 Stick packing of ZnII hexagon III-36-6: (a) top view; (b) side view; (c) F-F interactions between neighbouring p-fluorophenyl groups of the adjacent molecules (alkyl groups omitted for clarity) and (d) side view (with CHCl3 molecules in red/blue).  3.2.1.4 Electronic Absorption Spectra of Ring Fused Bisdipyrrin Metal Complexes  The ring fused bisdipyrrin metal grids and ZnII hexagons are all green solids upon crystallization, but III-27-4, III-29-4, III-31-4, III-32-4 and III-35-4 form dark blue solutions when dissolved in CHCl3 with the rest generating dark green solutions. Complex III-27-4 through III-36-6 were analyzed by electronic absorption spectroscopy (Figure 3-14). 82  Surprisingly, the absorption spectra of all complexes in choroform show two intense bands which may receive contributions from both spin-allowed ligand-centered (LC) transitions (π-π*) and metal-to-ligand charge transfer (MLCT) transitions (Table 3-1). The two bands display an almost identical logε value, but one is at longer wavelength and the other at shorter wavelength than the ligand’s main absorption. It is difficult to pair the band with its corresponding transition type at this stage, but the LC transition is probably responsible for the first band while the second band may be attributed to the MLCT transition. An ascending trend of λmax can be observed in the [2×2] ZnII grids (III-27-4 through III-33-4), which may be caused by substituent effects through the replacement of protons with an i-pentyl group or various aromatic rings. A large bathochromic shift (~ 19 nm) occurs with phenyl groups on the β’-position of the ligands (III-31-4 and III-32-4) instead of a proton (III-27-4) owing to the larger π-conjugated systems extended through the aromatic rings.72 Remarkably, a much larger bathochromic shift (~ 44 to 50 nm) was observed when the phenyl groups were attached to the α’-position of the ligands (III-33-4, III-34-4 and III-36-4), which may be further explained by the strong π-π interactions between the phenyl ring and the mean plane of the dipyrrin in each coordination center. The wavelengths of metal-to-ligand charge transfer bands for the metal grids and hexagons are marginally-shifted (0 to 2 nm) in III-34 and III-36 owing to the similar conformation of each coordination center and minimum overlap between the two adjacent π-systems (coordination centers) in the ZnII grids and hexagons.82  83  Figure 3-14 Electronic absorption spectra of cyclohexane bisdipyrrin metal complexes in chloroform: (a) III-27-4, III-29-4 through III-33-4 and III-35-4; (b) III-34 and (c) III-36.  84  Table 3-1 Spin-allowed ligand-centered transition band λmax1(nm) and metal-to-ligand charge transfer transition band λmax2(nm) for the metal grids and/or hexagons in chloroform.  Compound  λmax1/logε1  λmax2/logε2  Compound  λmax1/logε1  λmax2/logε2  III-24  647/5.24  —  III-32-4  594/5.64  632/5.63  III-25  644/5.21  —  III-33-4  625/5.68  661/5.66  III-26  644/5.31  —  III-34-4  623/5.69  659/5.67  III-27-4  575/5.63  613/5.53  III-34-6  622/5.88  659/5.89  III-29-4  590/5.60  629/5.56  III-35-4  643/5.56  692/5.49  III-30-4  615/5.67  658/5.58  III-36-4  620/5.44  657/5.42  III-31-4  593/5.58  632/5.56  III-36-6  618/5.59  655/5.58  85  3.3 Conclusions  The ring fused bisdipyrrin ligands are readily obtainable, and react with different metal ions (ZnII, CoII and NiII) to generate metal grids and/or hexagons. The metal grid is the only product when α’-free ring fused bisdipyrrin ligands are used while both the hexagon and the grid are formed when α’-phenyl bisdipyrrin ligands are introduced. The electronic absorption spectra of the metal grids and hexagons both exhibit two intense bands, one of which is attributed to spin-allowed ligand-centered transitions (small λmax) and the other from metal-to-ligand charge transfer transitions (large λmax). Structures of two of the [2×2] ZnII grids are confirmed by X-ray analysis, one of which is shaped as a square (III-27-4) and the other as a rhombus (III-33-4). Furthermore, one solid-state structure of a ZnII hexagon was revealed by X-ray analysis (III-36-6). The three-dimensional packing of the crystal structures of both III-33-4 and III-36-6 showed the complete overlap of individual molecules to achieve tunnel-like structures with different shapes and sizes. The hexagonal tunnel with a diameter of 12.8 Å in III-36-6 renders it a potential candidate for gas storage and separation.52-54 In general, the metal grids solved the isomer issue which proved to be a hurdle in the purification of the tetrameric circular helicates in chapter 2, and further allowed successful crystal growth to reveal the structures for characterization.  86  Chapter Four Heteroleptic Racks and Ladders  87  4.1 Design Strategy  meso-Unsubstituted bisdipyrrin salts through condensation have been widely investigated as the ligands for generation of metal complexes featuring double-45, 46 or triple-47 helical structures. meso-Aryl dipyrrins, which are stable in their free-base form, are usually synthesized through oxidation of dipyrromethanes.73 However, each type of the aforementioned ligands were previously treated with various metal ions to generate only homoleptic metal complexes.83 No heteroleptic metal complexes based on two distinct dipyrrin ligands have been reported thus far. Inspired by the work of Lehn and Schmittel on rack-type41 (Figure 4-1) and ladder-type24, 25 (Figure 4-2) complexes using bipyridine/terpyridine ligands, bisdipyrrin metal racks and ladders were successfully pursued.  Ph N Ar N Cu N N Ar  Ar N N  N  Cu Ar  N  Ph N Ar N Cu N N Ar N Ar N Cu N N Ar Ph  Ph  Figure 4-1 Rack-type CuI complexes using bipyridine ligands synthesized by Lehn (counterions omitted for clarity).  88  Ar  Ar  Me  Me  N Ph Cu N N N Ph  Ph N N Cu N Ph N  Ph Cu N N N Ph  N N  N  Me  Ph N Cu Ph N Me  N N Zn N N N  N  N N  Zn N N  Ar  Ar  Ar  Ar  N N N Zn N N Ar  N  N Zn  N N  N  Ar  Figure 4-2 Ladder-type CuI and ZnII complexes using bipyridine/terpyridine ligands reported by Lehn and Schmittel (counterions omitted for clarity).  89  4.2 Results and Discussion 4.2.1 Rack-Type Metal Complexes  The rigid diacetylene bisdipyrrins in Chapter II and the ring fused bisdipyrrins in Chapter III, together with meso-aryl dipyrrins and metal ions of tetrahedral geometry such as ZnII and CoII, were selected for preparation of the rack-type metal complexes. It is expected that in the resulting crystal structures, the metal ions are consecutively located on opposite sides of the rigid diacetylene bisdipyrrin backbone due to the two dipyrrin units being anti-parallel to one other. In contrast, the metal ions are aligned on the same side of the ring fused bisdipyrrin backbone owing to the parallel conformation of the two dipyrrin units.  4.2.1.1 Synthesis of Rack-Type Metal Complexes  The preparation of rack-type metal complexes began with the synthesis of several meso-aryl dipyrrins: IV-2 through IV-4 (Scheme 4-1). IV-3 was synthesized based on a previously reported procedure,84 starting with 4-formylbenzonitrile and 2-methylpyrrole.85 Compounds IV-2 and -4 were obtained using the same synthetic route. The ring fused bisdipyrrin ligand IV-6 was generated by combination of III-19 and IV-586 in the presence of HBr. Similarly, dialdehyde II-16 was condensed with 3-cyano-2,4-dimethylpyrrole IV-787 in the presence of HBr to afford the bisdipyrrin ligand IV-8 as the HBr salt.  90  R1 1  R  2  2  R  R  R2  1) TFA  +  2) DDQ  N H  CHO  R2  NH  R1 = R2 = Me  N  IV-2 67%  IV-1 50%  R1 = CN, R2 = H  IV-3 61%  R1 = H, R2 = Cl  IV-4 62%  COOH  HOOC  NH  HN  HBr  +  N H  N  CHO  HN  NH  N  2HBr III-19  IV-6 79%  IV-5 78%  CHO  HN  NH  OHC  II-16 50% HBr NC  N  CN  HN  NC  NH  N  2HBr N H  IV-8 85%  IV-7 39%  Scheme 4-1 Synthetic route to the ligands for preparation of rack-type metal complexes.  Combination of meso-aryl dipyrrin IV-2 and diacetylene bisdipyrrin II-22 with Zn(OAc)2•2H2O and NaOAc generates a mixture of ZnII complexes IV-9 (Scheme 4-2). Non-polar fractions were collected from flash chromatography on silica gel eluting with dichloromethane, followed by elution through a gel permeation chromatography (GPC) column with toluene to afford three fractions. The MALDI-TOF mass spectrometry shows that the first fraction IV-9-1 (red) is the trimeric ZnII complex of II-22, the second fraction IV-9-2 (orange) is 91  the rack-type ZnII complex and the last fraction (yellow) is the dimeric ZnII complex of IV-2. The rack-type ZnII complexes IV-10-2 and IV-11-2 were obtained using the same synthetic route and separation procedure. However, the crude complexes IV-10 and IV-11 were collected from flash chromatography on silica gel eluting with CH2Cl2/MeOH due to the polar cyanide group attached to the diacetylene bisdipyrrin ligand IV-8.  Treatment of meso-aryl dipyrrin IV-2 and ring fused bisdipyrrin IV-6 with Zn(OAc)2•2H2O and NaOAc forms a mixture of ZnII complexes IV-12 (Scheme 4-2). Non-polar fractions were collected from flash chromatography on silica gel eluting with dichloromethane, followed by elution through a GPC column with toluene to afford two fractions. The first fraction IV-12-1 (green) is the parallel rack-type ZnII complex and the second fraction (yellow) is the dimeric ZnII complex of IV-2 (confirmed by MALDI-TOF). The same procedure was used to afford rack-type ZnII complexes IV-13-1, IV-14-1 and IV-15-2. However, an extra fraction (blue) elutes from the GPC column first in the case of IV-15, which was confirmed to be the grid-type ZnII complex IV-15-1, a side product due to formation of the kinetically-controlled ZnII grid using α’-free bisdipyrrin ligand III-22. This also helps to explain why rack IV-15-2 was obtained in a very low yield (3%). Because no ZnII grids using ligand IV-6, which has methyl groups at the α’-positions, were observed in IV-12 through IV-14, perhaps more ligand IV-6 is available for synthesis of ZnII racks. Unfortunately, racks IV-12-1 through IV-14-1 were still obtained in a relatively low yield (4 to 7%), which is probably caused by poor solubility of the ring fused bisdipyrrin ligand IV-6 in common solvents.  92  In order to obtain the ZnII rack in a high yield, the ring fused bisdipyrrin ligands should be very soluble in chloroform to make it available to react with the meso-aryl dipyrrins and ZnII ions, and should also contain very bulky substituents at the α’-position of the terminal pyrrole rings to minimize the possible formation of homoleptic ZnII grids. Therefore, ligand III-24 was selected as a potential candidate to react with ligand IV-2, Zn(OAc)2•2H2O and NaOAc to generate a mixture of ZnII complexes IV-16 (Scheme 4-2). The same separation procedure was used to purify the mixture IV-16. Surprisingly, three dark green fractions were collected from the GPC column in addition to the yellow fraction (the same dimeric ZnII complex of IV-2). The first dark green fraction IV-16-1 is the [2A+3B] type ZnII complex (A = ligand IV-2 and B = ligand III-24), the second one IV-16-2 is the [2A+2B] type ZnII complex and the third one IV-16-3 is the parallel rack-type ZnII complex, all of which are confirmed by MALDI-TOF mass spectrometry. The introduction of ligand III-24 into the preparation of rack-type ZnII complexes proved to be very successful due to absence of the unwanted homoleptic ZnII grid and much higher yield (~17%) of rack IV-16-3. It seems that the zigzag-type ZnII complexes of ligand III-24 are favoured species compared to the ZnII grid owing to less steric hindrance in the former than that in the latter, which is caused by the very bulky 3,5-dimethylphenyl groups at the α’-position of the terminal pyrrole rings. The formation of [2A+3B] type ZnII complex IV-16-1 and [2A+2B] type ZnII complex IV-16-2 further confirms that zigzag-type intermediates (3B and 2B type ZnII complexes) exist in the reaction mixture. Ligand IV-2 (A) acts as a stopper to the zigzag-type intermediates and allows the facile separation and further characterization of zigzag-type ZnII complexes IV-16-1 and IV-16-2. However, only rack IV-17-3 and [2A+2B] type zigzag rack IV-17-2 were formed when CoII ions were introduced. 93  Scheme 4-2 Synthetic route for preparation of rack-type metal complexes. 94  4.2.1.2 1H NMR Spectra of ZnII Rack-Type and Zigzag Rack-Type Complexes  1  H NMR spectra of ZnII rack IV-16-3 and zigzag rack IV-16-2 dissolved in CDCl3 showed that  the two NH signals, previously at δ 14.27 and 12.52 for III-24, were no longer present, which supports the generation of the ZnII racks. Experiments determined that coordination of ligand III-24 and IV-2 with ZnII ions to form rack or zigzag rack-type complexes led to upfield shifts for all 1H signals. The meso-H and para-H signals from ligand III-24 in IV-16-3 shift upfield 0.1 ppm and 0.3 ppm, respectively. Remarkably, the ortho-H signals from ligand III-24 in IV-16-3 showed even further upfield shifts (0.66 ppm) owing to strong anisotropic effects (Figure 4-3). The meta-H signals from the mesityl groups in IV-16-3 split into a doublet instead of the singlet in ligand IV-2 due to differences in the surrounding chemical environment. However, the β-H signals from the dipyrrin in ligand IV-2 remain unchanged (doublet of doublets). The 1H signals in zigzag rack IV-16-2 can be divided into two sets, one of which belongs to the coordination site with ZnR (similar chemical environment in Rack IV-16-3) and the other belongs to the coordination site with ZnG (similar chemical environment in Grid III-33-4). The para-H, ortho-H and meso-H signals in the coordination site with ZnR are either the same or marginally shifted (0.04 ppm), compared to those in rack IV-16-3 due to the similar conformation of both coordination sites. Furthermore, the para-H, ortho-H and meso-H signals in the coordination site with ZnG are marginally shifted (0.07 to 0.19 ppm), compared to those in grid III-33-4 for the same reason. The meta-H signals from the mesityl groups in IV-16-2 remain the same as those in IV-16-3. Surprisingly, another set of the β-H signals from the dipyrrin in ligand IV-2 appears while the original set remains nearly unchanged. 95  Figure 4-3 1H NMR spectra (aromatic region) of ligand III-24 (400 MHz) and IV-2 (300 MHz) (top), ZnII rack IV-16-3 (300 MHz) (middle) and zigzag ZnII rack IV-16-2 (400 MHz) (bottom) in CDCl3.  96  4.2.1.3 X-Ray Analysis of ZnII Rack IV-16-3  A single crystal of IV-16-3 was grown from slow diffusion of hexane into a chloroform solution and the structure was investigated by X-ray diffraction analysis (Figure 4-4). The material crystallizes with one half-molecule in the asymmetric unit, related to another by a 2-fold axis of rotation. IV-16-3 is indeed a slightly distorted rack due to the repulsion between the two bulky mesityl groups at the meso-position in ligand IV-2. The distance between the two ZnII ions in one molecule is 8.11 Å and the Zn-N bond lengths range from 1.97-1.99 Å, which are close to those in the ZnII grid III-33-4. The dihedral angle between the mean planes of two dipyrrins coordinated to the same ZnII ion is 81.9º, which indicates each metal center has a much less distorted tetrahedral geometry than that in III-33-4. The dihedral angle between the mean planes of the two dipyrrins within each ligand III-24 is 11.4º owing to the sufficient flexibility of the cyclohexadiene ring. The dihedral angle between the plane of the mesityl group and the mean plane of the dipyrrin in ligand IV-2 is 84.4º. The two mesityl groups move away from each other (dihedral angle = 42.2º) due to the steric hindrance caused by the ortho-methyl groups oriented towards each other. Furthermore, the two mean planes of the dipyrrins in ligand IV-2 move towards each other (dihedral angle = 21.5º) owing to the bulky 3,5-dimethylphenyl groups attached to the α’-position of the terminal dipyrrin rings in ligand III-24. The three-dimensional packing structure of IV-16-3 exhibits no tunnel-like structure (Figure 4-5).  97  Figure 4-4 Crystal structure of ZnII rack IV-16-3: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level) and (b) space-filled representation.  Figure 4-5 Stick-packing of ZnII rack IV-16-3: (a) top view and (b) side view.  98  4.2.1.4 Electronic Absorption Spectra of Metal Racks and Zigzag Racks  The anti-parallel racks IV-9-2 through IV-11-2 are all red solids upon crystallization, but form red-orange solutions when dissolved in chloroform. However, the parallel racks IV-12-1 through IV-15-2 are all green solids upon crystallization, and generate blue solutions when dissolved in chloroform. The rack and zigzag racks from IV-16 are all dark green in the solid form and in solution while those from IV-17 are all dark blue. Complexes IV-9-2 through IV-17-2 were analyzed by electronic absorption spectroscopy (Figure 4-6). Remarkably, the absorption spectra of all ZnII racks in CHCl3 show two intense metal-to-ligand charge transfer (MLCT) transition bands (Table 4-1). The first bands peaking at 491-498 nm are attributed to MLCT transitions only engaging the meso-aryl dipyrrin ligands IV-2 through IV-4, and the shoulders of the first bands probably result from the spin-allowed ligand-centered (LC) transitions (π-π*) involving the aforementioned ligands. Similarly, the second bands peaking at 542-546 nm for anti-parallel racks and at 627-637 nm for parallel racks may receive contributions from MLCT transitions involving the diacetylene bisdipyrrin ligands (II-22 and IV-8) or ring fused bisdipyrrin ligands (III-22 and IV-6), respectively. The LC transitions engaging diacetylene or ring fused bisdipyrrin ligands are likely responsible for the shoulders of the second bands.  99  Figure 4-6 Electronic absorption spectra of rack-type ZnII complexes in chloroform: (a) IV-9-2 through IV-11-2; (b) IV-12-1 through IV-15-2; (c) IV-16 and (d) IV-17. Table 4-1 Metal-to-ligand charge transfer transition bands λmax (nm) for the ZnII racks in chloroform.  Rack  λmax1(nm)  λmax2(nm)  Rack  λmax1(nm)  λmax2(nm)  IV-9-2  495  542  IV-13-1  493  627  IV-10-2  494  546  IV-14-1  498  629  IV-11-2  496  546  IV-15-2  493  637  IV-12-1  491  628 100  As expected, the ZnII rack IV-16-3 and zigzag racks IV-16-2 and -1 all exhibit a sharp band (similar λmax1/logε1) with a left shoulder which is associated to the MLCT and LC transitions involving ligand IV-2 due to the fixed number of these ligands incorporated into the complexes (Table 4-2).40 Surprisingly, the shoulder of the second band gradually becomes a separate band with increased ratio of number of ring fused bisdipyrrin ligand III-24 to number of ZnII ions involved in the ZnII racks or zigzag racks. Grid III-33-4 which contains four ZnII ions and four ligands (ratio = 1) showed two intense bands with almost identical logε values, which further confirms that the second bands are attributed to MLCT transition while the shoulders receive contributions from the spin-allowed LC transitions. The wavelengths of the two intense bands in rack IV-16-3 and zigzag racks IV-16-2 and -1 are marginally-shifted (1 to 5 nm), which indicates a minimal overlap between the two distinct π-systems, coordination center with ZnR and that with ZnG, respectively.82 The electronic absorption spectra of complexes IV-16-3 through IV-16-1 display a hyperchromic shift for the bands associated with increasing number of ligand III-24. By contrast, the CoII rack IV-17-3 and zigzag rack IV-17-2 both showed three intense bands. Instead of a shoulder, a separate band appears for the LC transitions involving ligand III-24 due to a large wavelength difference (52 nm) between the second and third bands.  101  Table 4-2 Metal-to-ligand charge transfer transition bands λmax1 and λmax3 (nm) and spin-allowed ligand-centered transition band λmax2 (nm) for the metal racks and zigzag racks in chloroform.  Compound  λmax1(nm)/logε1  λmax2(nm)/logε2  λmax3(nm)/logε3  III-24  —  647/5.24  —  IV-16-3  492/5.29  —  667/5.25  IV-16-2  496/5.33  —  672/5.48  IV-16-1  497/5.31  623/5.46  669/5.56  III-33-4  —  625/5.68  661/5.66  IV-17-3  500/—  637/—  689/—  IV-17-2  504/—  639/—  702/—  4.2.2 Rigid Ladder-Type Metal Complexes  After the success of synthesizing parallel ZnII racks, formation of the metal ladder using the same procedure seems but one step away. With the ring fused bisdipyrrin ligands (the rails of the ladder) in hand, we only need to find a new kind of meso-aryl bisdipyrrin ligand to fit the other role (the rungs of the ladder). Inspired by ligand IV-2, used for synthesis of ZnII rack IV-16-3, a double meso-aryl dipyrrin ligand IV-18 was prepared for the ladder synthesis. Compound IV-19 was generated based on the same idea, but with α-free pyrrole instead.  102  4.2.2.1 Synthesis of Rigid Ladder-Type Metal Complexes  The preparation of rigid ladder-type metal complexes began with synthesis of meso-phenyl bisdipyrrin ligands IV-1882 and -19. Combination of α-free cyclohexane bisdipyrrin ligand III-22 with either IV-18 and Zn(OAc)2•2H2O or IV-19 and Cu(OAc)2•H2O in the presence of NaOAc afforded only the metal grid of ligand III-22. It seems that ligand III-22 can rapidly chelate the metal ions in the solution to generate the homoleptic grid which leaves ligands IV-18 or -19 to form polymers on their own. In order to overcome that obstacle, we have to link the metal ions to ligands IV-18 or -19 because if ligand III-22 wants to obtain the metal ions to form the complexes, it will have no choice but to react with ligands IV-18 or -19 with metal ions attached to them. Inspired by Cohen’s work on heteroleptic CuII dipyrrin complexes which are stable in solution and easy to purify on silica gel (Scheme 4-3),88 heteroleptic ZnII (IV-20) and CuII (IV-21) bisdipyrrin complexes were prepared (Scheme 4-4). Treatment of IV-18 with excess Zn(acac)2 affords the crude product which was recrystallized from CH2Cl2/Et2O to give the pure heteroleptic ZnII bisdipyrrin complex IV-20 in a high yield (75%). The CuII complex IV-21 was obtained using the same synthetic route. Surprisingly, IV-21 can be purified by simply passing it through a silica gel plug with chloroform as the eluent. However, no desired heteroleptic metal complexes were observed when IV-18 was paired with Cu(acac)2 or IV-19 with Zn(acac)2.  103  N +  NC NH  O O Cu O O  N O Cu N O  NC  41%  Scheme 4-3 Synthetic route for preparation of the heteroleptic CuII dipyrrin complex by Cohen.  R  R HN  N +  N  NH  R  R O O M O O  R  O  R N  N  N  N  M O  O M  R  O R  R = Me  IV-18 23%  M = ZnII  IV-20 75%  R=H  IV-19 16%  M = CuII  IV-21 31%  Scheme 4-4 Synthetic route for preparation of the heteroleptic ZnII and CuII bisdipyrrin complexes.  Treatment of heteroleptic bisdipyrrin metal complexes IV-20 or IV-21 and ring fused bisdipyrrin ligand III-22 with NaOAc in CHCl3/MeOH forms a mixture of ZnII complexes IV-22 or a mixture of CuII complexes IV-23 (Scheme 4-5). Non-polar fractions were collected from flash chromatography on silica gel eluting with CH2Cl2, followed by elution through a GPC column with toluene to afford two separate fractions for IV-23. The first fraction IV-23-G (dark blue) is the CuII grid of III-22 and the second one IV-23-L (dark green) is the rigid ladder-type CuII complex, both of which are confirmed by MALDI-TOF mass spectrometry. However, the two fractions in IV-22 always coelute on the GPC column due to the small 104  difference in their molecular weights and perhaps their similar conformations as well. Fortunately, these two complexes have different solubilities in dichloromethane. Thus, pure ZnII ladder IV-22-L can be obtained by using dichloromethane to wash out the ZnII grid IV-22-G from the mixture.  Scheme 4-5 Synthetic route for preparation of rigid ladder-type metal complexes.  Ideally, we hope that the metal-N bond is stronger than the metal-O bond in complexes IV-20 and IV-21, and also that ligand III-22 can break the metal-O bond and leave the metal-N bond intact. However, it turned out ligand III-22 did break metal-O bonds, and unfortunately  105  some of the metal-N bonds as well, which explained why metal grids were always formed in the reaction. The grids using α’-free ring fused bisdipyrrin ligands prefer metal ions with tetrahedral geometry due to their square-shaped structures, which is responsible for the fact that ZnII grid IV-22-G is more favoured than CuII grid IV-23-G. The ZnII ladder IV-22-L prefers metal ions with tetrahedral geometry to ease the repulsion between the α-methyl groups from complex IV-20 and the α-methylene groups from ligand III-22. The same repulsion does not exist in CuII ladder IV-23-L, thus, both ligands can easily adjust their conformations and arrangements to fulfill the coordination geometry the CuII ion prefers. Therefore, the ladder/grid ratio is much higher in IV-23 than that in IV-22. Other than ligand III-22, many other α’-aryl ring fused bisdipyrrin ligands have been investigated, but no ZnII or CuII ladders were observed. It is likely that the α’-aryl groups block the orientation that the heteroleptic metal complexes IV-20 and -21 try to adopt.  4.2.2.2 X-Ray Analysis of CuII Rigid Ladder IV-23-L  A single crystal of IV-23-L was grown from slow diffusion of hexane into a CH2Cl2 solution and the structure was investigated by X-ray diffraction analysis (Figure 4-7). The material crystallizes with one half molecule in the asymmetric unit related to a crystallographically equivalent fragment related by a c-glide plane. Complex IV-23-L is a heavily twisted ladder consisting of four CuII ions and two sets of distinct bisdipyrrin ligands. The distances between two adjacent CuII ions in one molecule are 8.14 and 12.33 Å due to the existence of two different ligands. The distance between two diagonal CuII ions in one molecule is 14.28 Å, 106  which is much longer than that in ZnII grid III-27-4 (11.47 Å). The CuII ladder IV-23-L displays significant differences in Cu-N bond length, which probably results from Jahn-Teller distortion. The dihedral angles between the mean planes of two dipyrrins coordinated to the same CuII ion are 53.5 and 57.8º, which indicates each metal center has a heavily distorted tetrahedral geometry. The dihedral angle between the mean planes of two dipyrrins within each ligand III-22 is 15.8º due to the sufficient flexibility of the cyclohexadiene ring. The dihedral angle between the mean planes of two dipyrrins in ligand IV-19 is 8.9º.  Figure 4-7 Crystal structure of CuII ladder IV-23-L: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level) and (b) space-filled representation.  The three-dimensional packing structure of IV-23-L exhibits a rectangular tunnel (11.3 Å on the diagonal) along the c axis in the crystal (Figure 4-8). The interesting tunnel structure may receive contributions from two sets of intermolecular CH/π interactions15,  89-92  between  individual molecules. The first set consists of four types (A, B, C and D) intermolecular CH/π interactions involving only the ligand III-22 between the neighboring molecules: type A is 107  formed between the methyl groups from 3,5-dimethylphenyl substituents and the centroid of the mean plane of the dipyrrin units belonging to the nearest molecules; type B between the ortho-H from 3,5-dimethylphenyl substituents and the centroid of the pyrrole rings of the same neighboring molecules; type C between the β-methyl groups from ligand III-22 and the centroid of the mean plane of the dipyrrin units belonging to the nearest molecules; type D between the methyl groups from 3,5-dimethylphenyl substituents and the centroid of the pyrrole rings belonging to the nearest molecules in adjacent layers. The second set contains one type (E) intermolecular CH/π interactions engaging both ligands (III-22 and IV-19) between the neighboring molecules: type E is formed between β-H from ligand IV-19 and the centroid of the pyrrole rings from ligand III-22 (Figure 4-9 and Table 4-3). As a consequence of these intermolecular interactions, a three-dimensional tunnel structure of IV-23-L along the c axis is eventually generated.  Figure 4-8 Stick-packing of CuII ladder IV-23-L: (a) top view; (b) and (c) side views.  108  (a)  A B  C B C C  C A B A  B A  (b)  D E  E D  Figure 4-9 Five types of CH/π interactions (A to E) in IV-23-L with stick representation: (a) top view and (b) side view. 109  Table 4-3 Intermolecular CH/π interactions in the crystal structure of CuII rigid ladder IV-23-L.  CH/π interactions  CH···centroid (Å)  C···centroid (Å)  Type A  2.76  3.53  Type B  2.80  3.40  Type C  2.70  3.58  Type D  3.06  3.93  Type E  3.05  3.83  4.2.2.3 Electronic Absorption Spectra of Metal Rigid Ladders  Both IV-22-L and IV-23-L are green solids upon crystallization, and form dark green solutions when dissolved in chloroform. Both ladders were analyzed by electronic absorption spectroscopy (Figure 4-10). As expected, the absorption spectra of ZnII ladder IV-22-L in chloroform shows two intense metal-to-ligand charge transfer (MLCT) transition bands (Table 4-4). The first band peaking at 484 nm receives contributions from MLCT transitions only involving the meso-aryl bisdipyrrin ligand IV-18, and the shoulder of the first band likely results from the spin-allowed ligand-centered (LC) transitions (π-π*) engaging the aforementioned ligand. Similarly, the second band peaking at 636 nm is attributed to MLCT transitions involving the ring fused bisdipyrrin ligand III-22. The LC transitions engaging ligand III-22 are 110  probably responsible for the shoulder of the second band. However, the absorption spectra of CuII ladder IV-23-L shows no shoulder peaks, and a very broad second band which is probably attributed to the sum of effects of LC and MLCT transitions engaging ligand III-22.  Figure 4-10 Electronic absorption spectra of rigid ladder-type metal complexes in chloroform: (a) ZnII ladder IV-22-L with ligand IV-18 and complex IV-20; (b) CuII ladder IV-23-L with ligand IV-19 and complex IV-21.  Table 4-4 Ligand-centered transition band λmax (nm) for the ligands and metal-to-ligand charge transfer transition bands λmax (nm) for metal complexes in chloroform.  Compound  λmax1(nm)  λmax2(nm)  Compound  λmax1(nm)  λmax2(nm)  IV-18  449  —  IV-19  478  —  IV-20  491  —  IV-21  469  —  IV-22-L  484  636  IV-23-L  482  611  111  4.2.3 Flexible Ladder-Type Metal Complexes  The ZnII ladder IV-22-L is very rigid, which receives contributions from the ring fused bisdipyrrin ligand III-22, the ZnII ions which prefer perfect tetrahedral geometry and the α-methyl groups from ligand IV-18. At this point, we reasoned that if we introduce a flexible bisdipyrrin ligand instead of ligand III-22, can we obtain a double-helical ladder such as that in DNA. In order to investigate this hypothesis, several β-β’ bisdipyrrin ligands linked with alkylene groups of different length were synthesized. The heteroleptic bisdipyrrin ZnII and CuII complexes (IV-20 and IV-21), again were selected as the source of the rungs of the ladder.  4.2.3.1 Synthesis of Flexible Ladder-Type Metal Complexes  The preparation of flexible bisdipyrrins started with the synthesis of another set of pyrrole-2-carbaldehyde derivatives (Scheme 4-6). In addition to many previously synthesized pyrrole-2-carbaldehydes with attached electron-donating groups, some electron-withdrawing groups are selected to introduce to the 4-position of the pyrrole-2-carbaldehydes. Compound IV-24 is the side product of the Vilsmeier reaction of II-14 while IV-26 is the main product of the Vilsmeier reaction. The same procedure was used to generate IV-27 as a brown solid. Compound IV-28 was synthesized by a former group member and the synthesis of IV-29 was based on a previously reported procedure.93  112  Scheme 4-6 Synthetic route for preparation of pyrrole-2-carbaldehyde derivatives.  A series of starting materials IV-30 (n = 1 to 5) for flexible bisdipyrrins were synthesized based on the previously reported procedures.46 Hydrogenation of IV-30 in the presence of palladium on activated carbon as the catalyst,46 followed by treatment of pyrrole-2-carbaldehyde derivatives IV-24 and IV-26 through IV-29 with HBr formed ligands IV-31 through IV-39 as their HBr salts. Combination of ligands IV-31 through IV-39 with heteroleptic bisdipyrrin ZnII complex IV-20 and NaOAc in CHCl3/MeOH forms a mixture of ZnII complexes IV-40 through IV-48 (Scheme 4-7). Non-polar fractions were collected from flash chromatography on neutral alumina eluting with CH2Cl2/MeOH, followed by elution through a GPC column with toluene to afford two yellow fractions in all cases. The first fraction is the flexible ladder-type ZnII complex and the second one is the ZnII double-helix of flexible bisdipyrrin ligand, both of which 113  are confirmed by MALDI-TOF mass spectrometry. However, the introduction of heteroleptic bisdipyrrin CuII complex IV-21 to the reaction only led to formation of a CuII double-helix, and no positive sign of generation of the flexible ladder-type complexes was observed.  CO2Bn  COOH  HN  HN  R1  H2 n HN  n  Pd/C  R1  R2  R1 N H  CHO R2  N  NH  HN  R1  HBr  R1  n  2HBr  R2  N R1  IV-31 to IV-39  HN CO2Bn  O N Zn O N  COOH  IV-30 N O Zn N O  ZnII =  Dimer  Ladder R1 = Me, R2 = COMe, n = 1: R1 = Me, R2 = COMe, n = 2: R1 = Me, R2 = COMe, n = 3: R1 = Me, R2 = COMe, n = 4: R1 = Me, R2 = COMe, n = 5:  IV-40-L IV-41-L IV-42-L IV-43-L IV-44-L  4% 4% 5% 8% 3%  IV-40-D IV-41-D IV-42-D IV-43-D IV-44-D  5% 9% 6% 17% 8%  R1 = Me, R2 = COPh, n = 3: R1 = Me, R2 = CO2Et, n = 3: R1 = H, R2 = COMe, n = 3: R1 = H, R2 = COPh, n = 3:  IV-45-L IV-46-L IV-47-L IV-48-L  16% 7% 2% 7%  IV-45-D IV-46-D IV-47-D IV-48-D  27% 17% 3% 20%  Scheme 4-7 Synthetic route for preparation of flexible ladder-type ZnII complexes. 114  4.2.3.2 1H NMR Spectra of ZnII Flexible Ladder-Type Complexes  The 1H NMR spectra of ZnII flexible ladders IV-40-L, IV-42-L and IV-43-L dissolved in CDCl3 showed that the β-H signals (doublet of doublets) from ligand IV-18, previously at δ 6.53 and 6.20 ppm for IV-18, were shifted and the shape of the peaks was changed as well, which supports the generation of the ZnII ladders (Figure 4-11). 1H NMR spectrum of ZnII flexible ladder IV-40-L exhibited five sets of doublet of doublets for the β-H signals while IV-42-L had three such sets and IV-43-L with only one. It appears that the β-H signals in 1H NMR spectra become simpler with increasing the length of the alkylene linker. It is thought that two isomers may exist in the solution when a methylene group was introduced as the spacer (IV-40-L), which causes the complexity of the signals. However, one isomer gradually dominates the other with increasing the length of the spacer, which may be responsible for the simplifying trend of the β-H signals at the end.  115  Figure 4-11 Partial 1H NMR spectra of ligand IV-18, ZnII ladders IV-40-L, IV-42-L and IV-43-L in CDCl3 (400 MHz).  116  4.2.3.3 X-Ray Analysis of ZnII Flexible Ladder IV-42-L  A single crystal of IV-42-L was grown from slow diffusion of hexane into a chloroform solution of IV-42-L and the structure was investigated by X-ray diffraction analysis (Figure 4-12). The material crystallizes with one half-molecule residing on an inversion centre. Surprisingly, instead of a ladder-type helicate, IV-42-L is a heavily twisted ladder-type mesocate consisting of four ZnII ions and two sets of distinct bisdipyrrin ligands. The distances between two adjacent ZnII ions in one molecule are 9.87 and 12.48 Å due to the existence of the two types of ligand. The distances between two diagonal ZnII ions in one molecule are 14.61 and 16.87 Å, which are a little longer than those in CuII ladder IV-23-L owing to the much longer introduced linker. Unlike the CuII ladder IV-23-L, the Zn-N bond lengths range from 1.96-2.00 Å, which shows slight differences in the metal-N bond lengths. The dihedral angles between the mean planes of two dipyrrins coordinated to the same ZnII ion are 85.8 and 76.4º, which indicates one metal center has a much more distorted tetrahedral geometry than the other. The dihedral angle between the mean planes of the two dipyrrins within each ligand IV-33 is 70.6º due to the flexibility of the propylene linker. The dihedral angle between the mean planes of the two dipyrrins in ligand IV-18 is 38.0º, which is much larger than that in CuII ladder IV-23-L (8.9º) which is probably due to the presence of the α-methyl groups in ligand IV-18.  117  Figure 4-12 Crystal structure of ZnII ladder IV-42-L: (a) ORTEP diagram (thermal ellipsoids are scaled to the 50% probability level) and (b) space-filled representation.  The three-dimensional packing structure of IV-42-L, like the CuII ladder IV-23-L, exhibits a much larger rectangular tunnel (14.7 Å on the diagonal) along the a axis in the crystal (Figure 4-13). This fascinating tunnel structure may receive contributions from two sets of intermolecular interactions between individual molecules. The first set consists of two types (A and B) intermolecular CH···O interactions94 between the neighboring molecules: type A is formed between the ortho-H of phenyl spacer from ligand IV-18 and O atom from the carbonyl group from ligand IV-33; type B between the β-H from ligand IV-18 and the same aforementioned O atom. The second set contains two types (C and D) intermolecular CH/π interactions15, 89-92, 95 between the neighboring molecules: type C is generated between the β-H from ligand IV-18 and the centroid of the pyrrole rings with attached carbonyl groups; type D between the β-H from ligand IV-18 and the centroid of the pyrrole rings from ligand IV-18 belonging to the neighboring molecules in adjacent layers (Figure 4-14 and Table 4-5). As a 118  consequence of these intermolecular interactions, a three-dimensional tunnel structure of IV-42-L along the a axis is eventually constructed.  Figure 4-13 Stick-packing of ZnII ladder IV-42-L: (a) top view; (b) and (c) side views.  (a)  A C B  B  C  A  119  (b)  D  D  D  D  Figure 4-14 Two types of CH/O interactions (A and B) and two types of CH/π interactions (C and D) in IV-42-L with stick representation: (a) top view and (b) side view.  Table 4-5 Intermolecular CH/O and CH/π interactions in the crystal structure of ZnII flexible ladder IV-42-L.  CH/O  CH/π  CH···centroid  CH···O (Å) interactions  C···centroid (Å) interactions  (Å)  Type A  2.47  Type C  3.02  3.78  Type B  3.02  Type D  3.27  4.06  120  4.2.3.4 Electronic Absorption Spectra of ZnII Flexible Ladders  The ZnII flexible ladders IV-40-L through IV-48-L are all orange solids upon crystallization, but form yellow solutions when dissolved in chloroform. All the ladders were analyzed by electronic absorption spectroscopy (Figure 4-15). The absorption spectra of all the ZnII ladders in chloroform exhibit one intense metal-to-ligand charge transfer (MLCT) transition band except for IV-45-L, which shows two instead (Table 4-6). An ascending trend of λmax can be observed in the ZnII ladders (IV-40-L through IV-44-L), which may be caused by substituent effects through increasing the length of the alkylene spacer in the flexible bisdipyrrin ligands. A bathochromic shift (~ 7 nm) occurs with methyl groups on the α’- and β’-position of the flexible ligands (IV-42-L and IV-45-L) instead of a proton (IV-47-L and IV-48-L) owing to the same aforementioned reason. The small difference between the wavelengths (λmax) of dimer IV-42-D and ladder IV-42-L indicates a minimal overlap between two distinct ligands in the latter.82  121  Figure 4-15 Electronic absorption spectra of flexible ladder-type ZnII complexes in chlororform: (a) ZnII ladder IV-40-L through IV-44-L; (b) ZnII ladder IV-42-L and IV-45-L through IV-48-L; (c) ZnII ladder IV-42-L and dimer IV-42-D.  Table 4-6 Metal-to-ligand charge transfer transition band(s) λmax (nm) for ZnII ladders in chloroform.  Ladder  λmax  Ladder  λmax  Ladder  λmax  IV-40-L  489  IV-43-L  492  IV-46-L  494  IV-41-L  490  IV-44-L  495  IV-47-L  486  IV-42-L  492  IV-45-L  495/509  IV-48-L  488 122  4.3 Conclusions  The present results indicate the formation of well-defined heteroleptic rack-type metal complexes showing rigid linear arrangements of the metal centers when two distinct ligands were treated with ZnII or CoII ions. Furthermore, longer zigzag racks are obtained when ring fused bisdipyrrin ligand III-24, with bulky 3,5-dimethylphenyl groups attached to the α’-position of the terminal pyrrole rings, are incorporated. However, this traditional method proves to be ineffective for the synthesis of ladder-type metal complexes. Surprisingly, the introduction of heteroleptic ZnII (IV-20) or CuII (IV-21) complexes as both the ligand and the metal ion source allows the easy generation of heteroleptic ladder-type metal complexes, which should be a very fruitful approach for the preparation of highly diversified assemblies. The electronic absorption spectra of the metal racks exhibit two intense peaks because the absorption spectrum of each ligand involved shows a very different λmax. The same conclusion applies to rigid metal ladders as well. By contrast, the absorption spectra of the flexible metal ladders only exhibit one intense peak due to the similar λmax of the two chosen ligands (except IV-45-L). Three crystal structures (IV-16-3, IV-23-L and IV-42-L) were generated through X-ray analysis. Complex IV-16-3 is a slightly distorted rack while both IV-23-L and IV-42-L are heavily twisted ladders. The three-dimensional packing of the crystal structures of both IV-23-L and IV-42-L achieved rectangular tunnel structures with different sizes (11.3 and 14.7 Å on the diagonal, respectively).  123  Chapter Five Experimental Sections  124  5.1 General Information  Unless otherwise noted, all starting materials and solvents were obtained from Aldrich, Fisher, Alfa Aesar or Oakwood and used without further purification. Thin layer chromatography (TLC) was performed with Merck Silica Gel 60 F254. Column chromatography was performed using silica gel from Silicycle Chemical Division (particle size: 230-400 mesh) or alumina from Fisher (neutral; 6% water added for brockman activity III; particle size: 60-235 mesh). The gel permeation chromatography (GPC) was carried out on Bio-Beads S-X1 beads (200-400 mesh). 1H NMR and  13  C NMR data were collected in  d6-DMSO, CD2Cl2 or CDCl3 on a Bruker Avance 300 MHz or a Bruker Avance 400 MHz spectrometer. Chemical shifts are reported relative to the residual non-deuterated solvent proton resonance as refernce standard (d6-DMSO at 2.50 ppm and 39.51 ppm for 1H NMR and NMR, respectively; CD2Cl2 at 5.32 ppm and 54.00 ppm for 1H NMR and  13  C  13  C NMR,  respectively; CDCl3 at 7.27 ppm and 77.00 ppm for 1H NMR and 13C NMR).  The low-resolution mass spectrometry (LRMS) and high-resolution mass spectrometry (HRMS) were taken on Kratos Concept IIHQ (EI), or Kratos MS50 (EI), or Brucker Esquire~LC (ESI) spectrometers. Mass spectra of the metal complexes were obtained by MALDI-TOF  mass  spectroscopy  in  the  presence  of  an  added  matrix,  2-[(2  E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]malononitrile (DCTB), on the Bruker Biflex IV instrument. UV-Visible spectra were recorded in chloroform at room temperature on Cary 5000 scan spectrophotometer. Elemental analysis was carried out on a Carlo Erba 125  Elemental Analyzer EA 1108.  The X-ray data were obtained on a Bruker X8 APEX II diffractometer with graphite monochromated Mo-Kα radiation. Data were collected and intregrated using the Brucker SAINT software. The structures were solved by direct methods and refined with SHELXTL crystallographic software package of Bruker-AXS.  Besides the complexes being isolated and characterized, the remainder is composed of unidentified polymeric materials.  126  5.2 Experimental Procedure and Data  TMS  II-1  TMS  (5-tert-butyl-1,3-phenylene)bis(ethyne-2,1-diyl)bis(trimethylsilane)  (II-1).63  To  a  mixture of 1,3-dibromo-5-tert-butylbenzene (2.0 g, 6.85 mmol), CuI (40 mg, 0.2 mmol) and Pd(PPh3)2Cl2 (246 mg, 0.35 mmol) in THF (25 mL) and piperidine (5 mL) was added ethynyltrimethylsilane (9.5 mL, 68.5 mmol). The reaction mixture was heated to reflux for 36 h. After removal of the organic solvent, the residue was treated with CH2Cl2 (50 mL). The organic layer was washed with water and brine, dried over anhydrous Na2SO4, and concentrated under reduced pressure to give the crude product. Flash chromatography on silica gel, eluting with hexanes, gave a pale yellow oil. Yield: 1.70 g (76%); 1H NMR (300MHz, CD2Cl2) δ (ppm) 7.44 (d, J = 1.5 Hz, 2H, Ar-H), 7.36 (t, J = 1.3 Hz, 1H, Ar-H), 1.29 (s, 9H, tBu), 0.24 (s, 18H, TMS).  II-2  1-tert-butyl-3,5-diethynylbenzene (II-2).63 To a solution of II-1 (1.86 g, 5.70 mmol) in THF (20 mL) and MeOH (50 mL) was added KOH (0.66 g, 11.8 mmol). The reaction mixture 127  was stirred for 4 h at room temperature. After removal of the organic solvent in vacuo, CH2Cl2 (50 mL) was introduced. The organic layer was washed with water and brine, dried over anhydrous Na2SO4, and concentrated under reduced pressure to give the crude product. Flash chromatography on silica gel, eluting with 10% CH2Cl2 in hexanes, afforded a brown liquid. Yield: 1.02 g (98%); 1H NMR (300MHz, CD2Cl2) δ (ppm) 7.52 (d, J = 1.4 Hz, 2H, Ar-H), 7.42 (t, J = 1.3 Hz, 1H, Ar-H), 3.13 (s, 2H, CH), 1.30 (s, 9H, tBu); EI MS (M+): m/z 182. HR-EI MS (M+) m/z calcd for C14H14 182.1096, found 182.1094.  I  N H  CHO  II-3 4-iodo-3,5-dimethylpyrrole-2-carbaldehyde  (II-3).64  To  a  mixture  of  3,5-dimethylpyrrole-2-carbaldehyde (0.74 g, 6 mmol) and K2CO3 (0.83 g, 6 mmol) in MeOH (300 mL) was added KI/I2 (1.90/1.83 g, 11.4/7.2 mmol, dissolved in 20 mL water and 15 mL MeOH). The reaction was stirred overnight at room temperature. Saturated Na2SO3 was then introduced to quench the excess I2. After removal of the organic solvent, the residue was washed with several portions of water, followed by filtration to give a white solid. Yield: 1.33 g (89%); 1  H NMR (300MHz, CD2Cl2) δ (ppm) 9.51 (s, 1H, CHO), 2.32 (s, 3H, CH3), 2.26 (s, 3H, CH3);  EI MS (M+): m/z 249. HR-EI MS (M+) m/z calcd for C7H8NOI 248.9651, found 248.9649.  128  I N H NC  CN  II-4 2-((4-iodo-3,5-dimethylpyrrol-2-yl)methylene)malononitrile (II-4). According to the previously reported procedure,66 some modifications have been made for synthesis of II-4. To a mixture of II-3 (1.5 g, 6 mmol) and malononitrile (0.79 g, 12 mmol) in EtOAc (20 mL) was added HNEt2 (0.6 mL). The reaction was stirred overnight at room temperature. After removal of the organic solvent, the residue was washed with a small amount of MeOH, and filtered to give a yellow solid. Yield: 1.60 g (90%); 1H NMR (300MHz, DMSO-d6) δ (ppm) 11.56 (s, 1H, NH), 7.95 (s, 1H, CH), 2.35 (s, 3H, CH3), 2.15 (s, 3H, CH3); 13C NMR (100MHz, DMSO-d6) δ (ppm) 145.1, 143.3, 139.4, 124.5, 116.2, 115.3, 76.2, 64.6, 14.7, 13.6; EI MS (M+): m/z 297. HR-EI MS (M+) m/z calcd for C10H8N3I 296.9763, found 296.9764.  OHC  CHO HN  II-5  NH  4,4'-(5-tert-butyl-1,3-phenylene)bis(ethyne-2,1-diyl)bis(3,5-dimethylpyrrole-2-carbalde hyde) (II-5). According to the previously reported procedure,65 some modifications have been made for synthesis of II-5. To a mixture of II-2 (0.40 g, 2.18 mmol), II-4 (1.30 g, 4.36 mmol) and CuI (20 mg, 0.1 mmol) in THF (20 mL) and piperidine (10 mL) was added Pd(PPh3)2Cl2 129  (70 mg, 0.1 mmol). The reaction mixture was purged with hydrogen at 1 atm and stirred for overnight. After removal of the organic solvent, EtOH (30 mL) was introduced, followed by addition of KOH (2.24 g, 40 mmol, dissolved in 5 mL water). The reaction mixture was refluxed for 3 h. The reaction was allowed to cool to room temperature, and then poured into 100 mL water and 100 mL CHCl3. The organic layer was washed with water, brine and dried over anhydrous Na2SO4. After removal of the organic solvent, the residue was purified by flash chromatography on silica gel, eluting with 1% MeOH in CH2Cl2, to give a brown solid. Yield: 200 mg (22%); 1H NMR (400MHz, DMSO-d6) δ (ppm) 12.02 (br. s, 2H, NH), 9.53 (s, 2H, CHO), 7.46 (d, J = 1.1 Hz, 4H, Ar-H), 7.41 (t, J = 1.7 Hz, 2H, Ar-H), 2.37 (s, 6H, CH3), 2.33 (s, 6H, CH3), 1.31 (s, 9H, tBu); 13C NMR (100MHz, DMSO-d6) δ (ppm) 177.0, 151.7, 140.8, 130.3, 127.9, 127.3, 123.5, 105.3, 92.4, 83.0, 34.4, 30.8, 11.9, 9.6; EI MS (M+): m/z 424. HR-EI MS (M+) m/z calcd for C28H28N2O2 424.2151, found 424.2149.  HN N  2HBr  II-6  NH N  bisdipyrrin ligand (II-6).67 To a mixture of II-5 (161 mg, 0.38 mmol) and 2,4-dimethylpyrrole (0.09 mL, 0.88 mmol) in THF (75 mL) and methanol (25 mL) was added 33% hydrogen bromide in acetic acid (2.0 mL). The solution quickly turned from yellow to 130  orange and then to an orange suspension. The suspension was stirred for 2 h at room temperature, and then filtered to collect the precipitate, which was rinsed with THF to give an orange solid. Yield: 250 mg (90%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.32 (d, J = 1.6 Hz, 2H, Ar-H), 7.29 (m, 1H, Ar-H), 7.06 (s, 2H, meso-H), 6.14 (s, 2H, pyrrole-H), 2.56 (s, 6H, CH3), 2.46 (s, 6H, CH3), 2.32 (s, 6H, CH3), 2.23 (s, 6H, CH3), 1.17 (s, 9H, tBu); ESI MS (M+H) +: m/z 579.7; HR-ESI MS (M+H) +: m/z calcd for C40H43N4: 579.3488; found: 579.3491. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 501.0 (1.567).  CoII bisdipyrrin complex (II-7-2).67 To a solution of II-6 (74 mg, 0.1 mmol) in CHCl3/MeOH (20 mL/10 mL) was added a solution of Co(OAc)2•4H2O (37 mg, 0.15 mmol) in MeOH (1 mL). The reaction mixture was stirred for 1 h before a solution of NaOAc (82 mg, 1 mmol) in MeOH (1 mL) was added. After stirring overnight, the solvent was removed by rotary evaporation. A crude mixture of the metal complexes was obtained after filtration through a short column using silica gel and CH2Cl2. The target complexes were separated by gel permeation chromatography eluting with toluene to give a green metallic solid. Yield: 11 mg (17%); MALDI-TOF calcd. 1270.5, found 1270.4 [(M)+]; Elemental analysis (%) calcd. 8.81 (N), 75.57 (C), 6.34 (H) found 8.69 (N), 75.58 (C), 6.62 (H); UV/Vis (CHCl3) λmax nm (logε): 380.0 (4.51), 516.0 (5.35).  131  I  I  N  II-8 9-ethyl-3,6-diiodocarbazole (II-8). According to the previously reported procedure,96 some modifications have been made for synthesis of II-8. To a solution of 9-ethylcarbazole (3.5 g, 17.9 mmol) in CHCl3 (160 mL) and acetic acid (50 mL) was added NIS (8.4 g, 36.7 mmol). The reaction mixture was stirred overnight at room temperature. Saturated Na2SO3 was then introduced to quench the excess NIS. The organic layer was washed with several portions of water, saturated NaHCO3 and brine, dried over anhydrous Na2SO4, and then concentrated under reduced pressure to give the crude product. Flash chromatography on silica gel, eluting with CH2Cl2, gave a yellow solid. Yield: 6.0 g (75%); 1H NMR (300MHz, CDCl3) δ (ppm) 8.61 (d, J = 1.5 Hz, 2H, carbazole-H), 7.73 (dd, J = 8.7 and 1.6 Hz, 2H, carbazole-H), 7.50 (d, J = 8.6 Hz, 2H, carbazole-H), 4.41 (q, J = 7.2 Hz, 2H, CH2), 1.26 (t, J = 7.1 Hz, 3H, CH3); EI MS (M+): m/z 447. HR-EI MS (M+) m/z calcd for C14H11NI2 446.8981, found 446.8977.  TMS  TMS  N  II-9 9-ethyl-3,6-bis((trimethylsilyl)ethynyl)carbazole (II-9). According to the previously reported procedure,63 some modifications have been made for synthesis of II-9. To a mixture of 132  II-8 (1.8 g, 4.03mmol), CuI (40 mg, 0.2 mmol) and Pd(PPh3)2Cl2 (140 mg, 0.2 mmol) in THF (45 mL) and piperidine (10 mL) was added ethynyltrimethylsilane (3.4 mL, 24.2 mmol). The reaction mixture was stirred overnight at room temperature. After removal of the organic solvent, the residue was dissolved in CH2Cl2 (50 mL). The organic layer was washed by water and brine, dried over anhydrous Na2SO4, and then concentrated under reduced pressure to give the crude product. Flash chromatography on silica gel, eluting with hexanes, gave a yellow oil. Yield: 1.40 g (90%); 1H NMR (300MHz, CDCl3) δ (ppm) 8.21 (d, J = 0.9 Hz, 2H, carbazole-H), 7.59 (dd, J = 8.4 and 1.3 Hz, 2H, carbazole-H), 7.32 (d, J = 8.7 Hz, 2H, carbazole-H), 4.34 (q, J = 7.3 Hz, 2H, CH2), 1.43 (t, J = 7.3 Hz, 3H, CH3), 0.30 (s, 18H, TMS); EI MS (M+): m/z 387. HR-EI MS (M+) m/z calcd for C24H29NSi2 387.1839, found 387.1838.  N  II-10 9-ethyl-3,6-diethynylcarbazole (II-10). The same procedure was used as in the synthesis of II-2, starting from II-9 (2.20 g, 5.70 mmol) to afford pale yellow needles. Yield: 1.37 g (99%); 1  H NMR (300MHz, CDCl3) δ (ppm) 8.23 (d, J = 0.9 Hz, 2H, carbazole-H), 7.62 (dd, J = 8.6 and  1.5 Hz, 2H, carbazole-H), 7.34 (d, J = 8.8 Hz, 2H, carbazole-H), 4.34 (q, J = 7.0 Hz, 2H, CH2), 3.10 (s, 2H, CH), 1.43 (t, J = 7.3 Hz, 3H, CH3); EI MS (M+): m/z 243. HR-EI MS (M+) m/z calcd for C18H13N 243.1048, found 243.1046.  133  CHO  OHC  NH  HN  N  II-11 4,4'-(9-ethyl-9H-carbazole-3,6-diyl)bis(ethyne-2,1-diyl)bis(3,5-dimethyl-1H-pyrrole-2-c arbaldehyde) (II-11). The same procedure was used as in the synthesis of II-5, starting from II-10 (0.53 g, 2.18 mmol) to afford a brown solid. Yield: 0.39 g (37%); 1H NMR (400MHz, DMSO-d6) δ (ppm) 11.98 (br. s, 2H, NH), 9.54 (s, 2H, CHO), 8.43 (s, 2H, carbazole-H), 7.65 (d, J = 8.7 Hz, 2H, carbazole-H), 7.59 (dd, J = 8.5 and 1.8 Hz, 2H, carbazole-H), 4.47 (q, J = 7.6 Hz, 2H, CH2), 2.41 (s, 6H, CH3), 2.37 (s, 6H, CH3), 1.33 (t, J = 7.6 Hz, 3H, CH3);  13  C NMR  (100MHz, DMSO-d6) δ (ppm) 176.9, 140.2, 139.3, 129.2, 127.9, 123.7, 121.9, 113.8, 109.7, 106.1, 106.0, 93.9, 80.6, 37.2, 13.7, 12.0, 9.7; EI MS (M+): m/z 485. HR-EI MS (M+) m/z calcd for C32H27N3O2 485.2103, found 485.2101.  134  N  N NH  HN 2HBr  N  II-12 bisdipyrrin ligand (II-12). The same procedure was used as in the synthesis of II-6, starting from II-11 (184 mg, 0.38 mmol) to afford a red solid. Yield: 265 mg (87%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 8.07 (s, 2H, carbazole-H), 7.45 (d, J = 8.5 Hz, 2H, carbazole-H), 7.25 (d, J = 8.4 Hz, 2H, carbazole-H), 7.05 (s, 2H, meso-H), 6.12 (s, 2H, pyrrole-H), 2.58 (s, 6H, CH3), 2.44 (s, 6H, CH3), 2.34 (s, 6H, CH3), 2.23 (s, 6H, CH3), 1.27 (t, J = 7.0 Hz, 3H, CH3); ESI MS (M+H) +: m/z 640.8; HR-ESI MS (M+H) +: m/z calcd for C44H42N5: 640.3440; found: 640.3450. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 500.0 (0.958).  CoII bisdipyrrin complex (II-13-2). The same procedure was used as in the synthesis of II-7-2, starting from II-12 (80 mg, 0.1 mmol) to afford a green metallic solid. Yield: 15 mg (22%); MALDI-TOF calcd. 1392.5, found 1392.3 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 380.1 (4.63), 515.0 (5.38).  135  O  N H  II-14 1-(2,4-dimethylpyrrol-3-yl)ethanone (II-14).70 To t-butyl 4-acetyl-3,5-dimethylpyrrole-2carboxylate (0.95 g, 4 mmol) in a 50 mL round-bottom flask was added TFA (10 mL). The reaction mixture was stirred for 2 h at room temperature. After the mixture was poured into well-stirred 500 mL ice-water, a pink solid started to precipitate. The precipitate was collected by filtration and washed with a large amount of water to remove the TFA to give a pink solid. Yield: 320 mg (58%); 1H NMR (300MHz, DMSO-d6) δ (ppm) 10.88 (br. s, 1H, NH), 6.38 (s, 1H, pyrrole-H), 2.38 (s, 3H, CH3), 2.29 (s, 3H, CH3), 2.14 (s, 3H, CH3); EI MS (M+): m/z 137. HR-EI MS (M+) m/z calcd for C8H11NO 137.0841, found 137.0841.  N H  CHO  II-15 4-ethynyl-3,5-dimethylpyrrole-2-carbaldehyde  (II-15).  The  previously  reported  procedure71 was used as in the synthesis of II-15, starting from II-14 (9.0 g, 65.6 mmol) to afford a white solid. Yield: 2.86 g (30%); 1H NMR (300MHz, DMSO-d6) δ (ppm) 11.92 (br. s, 1H, NH), 9.49 (s, 1H, CHO), 4.12 (s, 1H, CH), 2.27 (s, 3H, CH3), 2.24 (s, 3H, CH3); EI MS (M+): m/z 147. HR-EI MS (M+) m/z calcd for C9H9NO 147.0684, found 147.0683.  136  CHO  HN  NH  OHC  II-16 4,4'-(buta-1,3-diyne-1,4-diyl)bis(3,5-dimethylpyrrole-2-carbaldehyde)  (II-16).  According to the previously reported procedure,65 some modifications have been made for synthesis of II-16. To a mixture of II-15 (250 mg, 1.70 mmol), Pd(PPh3)2Cl2 (120 mg, 0.17 mmol) and α-chloroacetone (0.6 mL, 7.8 mmol) in THF (20 mL) was added NEt3 (1 mL). The mixture was stirred for 1 h at room temperature. After addition of CuI (50 mg, 0.26 mmol), the reaction mixture was stirred overnight. After removal of the organic solvent, the residue was purified by flash chromatography on silica gel, eluting with 1% MeOH in CH2Cl2, to give a yellow solid. Yield: 125 mg (50%); 1H NMR (300MHz, DMSO-d6) δ (ppm) 12.11 (br. s, 2H, NH), 9.52 (s, 2H, CHO), 2.32 (s, 6H, CH3), 2.29 (s, 6H, CH3); 13C NMR (75MHz, DMSO-d6) δ (ppm) 177.3, 142.9, 127.8, 104.1, 86.4, 77.5, 75.4, 12.1, 9.7; EI MS (M+): m/z 292. HR-EI MS (M+) m/z calcd for C18H16N2O2 292.1212, found 292.1215.  N H  COOH  II-17 4-t-butyl-3,5-dimethylpyrrole-2-carboxylic acid (II-17).97 To a solution of ethyl 4-t-butyl-3,5-dimethylpyrrole-2-carboxylate (0.56 g, 2.5 mmol) in EtOH (30 mL) was added KOH (1.4 g, 25 mmol, dissolved in 5 mL water). The reaction mixture was refluxed for 3 h. 137  After removal of the solvent, the residue was treated with 400 mL water, followed by addition of acetic acid to generate the precipitate. The precipitate was filtered and washed with several portions of water to remove excess acetic acid to give a pink solid. Yield: 385 mg (79%); 1H NMR (300MHz, DMSO-d6) δ (ppm) 11.81 (br. s, 1H, NH), 10.77 (s, 1H, COOH), 2.37 (s, 3H, CH3), 2.27 (s, 3H, CH3), 1.29 (s, 9H, tBu); 13C NMR (100MHz, CDCl3) δ (ppm) 166.3, 129.6, 129.6, 129.3, 116.2, 33.0, 31.7, 16.5, 13.5; EI MS (M+): m/z 195. HR-EI MS (M+) m/z calcd for C11H17NO2 195.1259, found 195.1260.  O Ph N H  II-19 (2,4-dimethyl-1H-pyrrol-3-yl)(phenyl)methanone  (II-19).  The  previously  reported  procedure98 was used as in the synthesis of II-19 to afford a brown solid. Yield: 305 mg (28%); 1  H NMR (300MHz, CDCl3) δ (ppm) 8.15 (br. s, 1H, NH), 7.69 – 7.72 (m, 2H, Ar-H), 7.49 –  7.53 (m, 1H, Ar-H), 7.40 – 7.45 (m, 2H, Ar-H), 6.42 (s, 1H, pyrrole-H), 2.18 (s, 3H, CH3), 2.00 (s, 3H, CH3); EI MS (M+): m/z 199. HR-EI MS (M+) m/z calcd for C13H13NO 199.0997, found 199.0996. O MeO N H  II-20 Methyl 2,4-dimethylpyrrole-3-carboxylate (II-20). The same procedure was used as in the 138  synthesis of II-14, starting from 2-t-butyl 4-methyl 3,5-dimethylpyrrole-2,4-dicarboxylate (1.01 g, 4 mmol) to afford a pink solid. Yield: 550 mg (90%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.94 (br. s, 1H, NH), 6.36 (s, 1H, pyrrole-H), 3.81 (s, 3H, CH3), 2.49 (s, 3H, CH3), 2.24 (s, 3H, CH3); EI MS (M+): m/z 153. HR-EI MS (M+) m/z calcd for C8H11NO2 153.0790, found 153.0788.  N  HN NH  N  2HBr  II-21 bisdipyrrin ligand (II-21).67 To a mixture of II-16 (200 mg, 0.68 mmol) and II-17 (332 mg, 1.7 mmol) in THF (75 mL) and MeOH (25 mL) at 75°C was added 33% hydrogen bromide in acetic acid (2.0 mL). The reaction mixture was stirred for 4 h at 75°C. Removal of the organic solvent gave the crude product as a red solid. Trituration of the crude solid with diethyl ether gave a red solid. Yield: 370 mg (76%); 1H NMR (300MHz, CD2Cl2) δ (ppm) 13.49 (br. s, 2H, NH), 13.18 (br. s, 2H, NH), 7.18 (s, 2H, meso-H), 2.91 (s, 6H, CH3), 2.73 (s, 6H, CH3), 2.48 (s, 6H, CH3), 2.44 (s, 6H, CH3), 1.41 (s, 18H, tBu);  13  C NMR (75MHz, CD2Cl2) δ (ppm) 159.8,  156.3, 146.5, 144.3, 138.0, 128.6, 125.4, 120.0, 110.7, 80.3, 74.8, 33.8, 31.5, 18.0, 13.7, 13.6, 11.8; ESI MS (M+H)+: m/z 559.5; Anal. Calcd. for: C38H38Br2N4: C, 63.34; H, 6.71; N, 7.77. Found: C, 62.96; H, 6.83; N, 7.90; UV/Vis (CHCl3) λmax nm (logε): 531.0 (5.15).  139  N  HN NH  N  2HBr  II-22 bisdipyrrin ligand (II-22). According to the previously reported procedure,67 some modifications have been made for synthesis of II-22. To a mixture of II-16 (100 mg, 0.34 mmol) and II-18 (0.09 ml, 0.68 mmol) in THF (75 mL) and MeOH (25 mL) was added 33% hydrogen bromide in acetic acid (2.0 mL). The solution quickly turned from yellow to dark red, and then to a red suspension. The suspension was stirred for 2 h at room temperature, and then filtered to collect the precipitate, which was rinsed with THF to give a red solid. Yield: 180 mg (80%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.01 (s, 2H, meso-H), 2.47 (s, 6H, CH3), 2.43 (s, 6H, CH3), 2.30 (q, J = 7.6 Hz, 4H, CH2), 2.26 (s, 6H, CH3), 2.15 (s, 6H, CH3), 0.91 (t, J = 7.6 Hz, 6H, CH3); ESI MS (M+H)+: m/z 503.5; HR-ESI MS (M+H)+: m/z calcd for C34H39N4: 503.3175; found: 503.3177. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 525.0 (1.084).  O O  N  HN NH  N  Ph  Ph 2HBr  II-23 bisdipyrrin ligand (II-23). The same procedure was used as in the synthesis of II-22, starting from II-16 (100 mg, 0.34 mmol) and II-19 (136 mg, 0.68 mmol) to give a red solid. Yield: 180 mg (65%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.55 (d, J = 7.6 Hz, 4H, Ar-H), 7.46 (t, J = 7.5 Hz, 2H, Ar-H), 7.32 (t, J = 7.6 Hz, 4H, Ar-H), 7.23 (s, 2H, meso-H), 140  2.59 (s, 6H, CH3), 2.41 (s, 6H, CH3), 2.34 (s, 6H, CH3), 2.15 (s, 6H, CH3); 13C NMR (100MHz, CDCl3/CD3OD = 2/1) δ (ppm) 191.9, 160.2, 156.6, 150.0, 145.4, 137.9, 133.5, 128.8, 128.6, 128.1, 126.7, 126.0, 122.5, 112.4, 80.6, 73.4, 13.8, 13.2, 11.3, 11.1; ESI MS (M+H)+: m/z 655.6; HR-ESI MS (M+H)+: m/z calcd for C44H39N4O2: 655.3073; found: 655.3086. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 531.0 (1.141).  O O  N  HN NH  N  OMe  MeO 2HBr  II-24 bisdipyrrin ligand (II-24). The same procedure was used as in the synthesis of II-22, starting from II-16 (100 mg, 0.34 mmol) and II-20 (104 mg, 0.68 mmol) to give a dark red solid. Yield: 150 mg (64%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.27 (s, 2H, meso-H), 3.70 (s, 6H, CH3), 2.70 (s, 6H, CH3), 2.59 (s, 6H, CH3), 2.46 (s, 6H, CH3), 2.34 (s, 6H, CH3); ESI MS (M+H)+: m/z 563.6; HR-ESI MS (M+H)+: m/z calcd for C34H35N4O4: 563.2658; found: 563.2667. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 522.0 (0.533).  ZnII bisdipyrrin complexes (II-25).67 To a solution of II-21 (72 mg, 0.1 mmol) in CHCl3/MeOH (20 mL/10 mL) was added a solution of Zn(OAc)2•2H2O (33 mg, 0.15 mmol) in MeOH (1 mL), followed by addition of a solution of NaOAc (82 mg, 1 mmol) in MeOH (1 mL). After stirring overnight, the solvent was removed by rotary evaporation. A crude mixture of the metal complexes was obtained after filtration through a short column using silica gel and 141  CH2Cl2. The crude compound was then purified using gel permeation chromatography eluting with toluene. The target metal complexes were obtained as dichroic red/green solids. II-25-3 (trimer): Yield: 12 mg (19%); 1H NMR (CDCl3, 300 MHz) δ (ppm) 7.02 (s, 6H, meso-H), 2.38-2.40 (m, 36H, CH3), 2.11-2.13 (m, 18H, CH3), 1.95-2.00 (m, 18H, CH3), 1.33 (s, 54H, t-Bu);  13  C NMR (CD2Cl2, 75 MHz) δ (ppm) 162.1, 158.9, 142.2, 139.6, 138.6, 137.5,  134.9, 121.7, 109.6, 79.9, 78.4, 33.6, 31.9, 20.3, 15.4, 13.3, 11.4; MALDI-TOF calcd. 1860.9, found 1860.9 [(M)+]; Anal. Calcd. for: C114H132N12Zn3: C, 73.36; H, 7.13; N, 9.01. Found: C, 73.35; H, 7.36; N, 8.76; UV/Vis (CHCl3) λmax nm (logε): 544.0 (5.81). II-25-4 (tetramer): Yield: 2 mg (3%); 1H NMR (CDCl3, 300 MHz) δ (ppm) 7.01 (s, 6H, meso-H), 2.37-2.39 (m, 36H, CH3), 2.12 (s, 18H, CH3), 1.98 (d, J = 7.7 Hz, 18H, CH3), 1.33 (d, J = 2.5 Hz, 54H, t-Bu); MALDI-TOF calcd. 2481.1, found 2481.1 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 544.0 (5.93). II-25-5 (pentamer): Yield: trace; MALDI-TOF calcd. 3101.4, found 3101.3 [(M)+];  ZnII bisdipyrrin complexes (II-26). The same procedure was used as in the synthesis of II-25, starting from II-22 (66 mg, 0.1 mmol) to afford dichroic red/green solids. II-26-3 (trimer): Yield: 10 mg (17%); 1H NMR (CDCl3, 300 MHz) δ (ppm) 6.97 (s, 6H, meso-H), 2.32-2.40 (m, 30H, CH2 and CH3), 2.23 (s, 18H, CH3), 1.93-2.01 (m, 36H, CH3), 1.02 (t, J = 7.5 Hz, 18H, CH3);  13  C NMR (CDCl3, 100 MHz) δ (ppm) 161.3, 158.9, 141.9, 139.3,  137.8, 134.0, 132.0, 121.3, 109.1, 79.4, 77.8, 17.9, 15.2, 14.8, 14.7, 11.1, 9.8; MALDI-TOF calcd. 1692.7, found 1692.8 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 542.0 (5.82). II-26-4 (tetramer): Yield: 1 mg (2%); 1H NMR (CDCl3, 300 MHz) δ (ppm) 6.96 (s, 6H, 142  meso-H), 2.33-2.39 (m, 30H, CH2 and CH3), 2.22 (s, 18H, CH3), 2.01 (dd, J = 9.1, 2.4 Hz, 18H, CH3), 1.92 (s, 18H, CH3), 1.02 (dt, J = 7.4, 2.4 Hz, 18H, CH3); MALDI-TOF calcd. 2256.9, found 2256.9 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 542.0 (5.90). II-26-5 (pentamer): Yield: trace; MALDI-TOF calcd. 2821.1, found 2821.2 [(M)+];  ZnII bisdipyrrin complexes (II-27). The same procedure was used as in the synthesis of II-25, starting from II-23 (82 mg, 0.1 mmol) to afford dichroic red/green solids. II-27-3 (trimer): Yield: 13 mg (18%); 1H NMR (CDCl3, 400 MHz) δ (ppm) 7.71 (dd, J = 7.0, 1.4 Hz, 12H, Ar-H), 7.53-7.56 (m, 6H, Ar-H), 7.43-7.47 (m, 12H, Ar-H), 7.19 (d, J = 1.8 Hz, 6H, meso-H), 2.43-2.45 (m, 18H, CH3), 2.23 (s, 18H, CH3), 2.02-2.09 (m, 36H, CH3);  13  C NMR  (CDCl3, 100 MHz) δ (ppm) 194.0, 163.6, 159.7, 147.1, 144.1, 144.0, 140.3, 136.9, 136.3, 132.3, 129.1, 128.4, 124.2, 112.4, 80.5, 77.5, 29.7, 16.8, 12.0, 11.4; MALDI-TOF calcd. 2148.6, found 2148.7 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 554.0 (5.68). II-27-4 (tetramer): Yield: 7 mg (10%); 1H NMR (CDCl3, 300 MHz) δ (ppm) 7.71 (dd, J = 6.9, 1.2 Hz, 12H, Ar-H), 7.55 (dt, J = 7.2, 1.1 Hz, 6H, Ar-H), 7.45 (dt, J = 7.1, 1.3 Hz, 12H, Ar-H), 7.19 (s, 6H, meso-H), 2.44 (d, J = 2.6 Hz, 18H, CH3), 2.22 (s, 18H, CH3), 2.11 (d, J = 3.9 Hz, 18H, CH3), 2.03 (s, 18H, CH3); MALDI-TOF calcd. 2872.7, found 2872.6 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 553.0 (5.82). II-27-5 (pentamer): Yield: 2 mg (3%); 1H NMR (CDCl3, 400 MHz) δ (ppm) 7.71 (d, J = 7.6 Hz, 12H, Ar-H), 7.54 (t, J = 6.9 Hz, 6H, Ar-H), 7.45 (t, J = 7.0 Hz, 12H, Ar-H), 7.19 (s, 6H, meso-H), 2.43 (s, 18H, CH3), 2.22 (s, 18H, CH3), 2.12 (s, 18H, CH3), 2.01 (s, 18H, CH3); MALDI-TOF calcd. 3590.9, found 3592.0 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 553.0 (5.92). 143  ZnII bisdipyrrin complexes (II-28). The same procedure was used as in the synthesis of II-25, starting from II-24 (72 mg, 0.1 mmol) to afford dichroic red/green solids. II-28-3 (trimer): Yield: 9 mg (15%); 1H NMR (CDCl3, 300 MHz) δ (ppm) 7.23 (t, J = 2.1 Hz, 6H, meso-H), 3.80 (d, J = 2.4 Hz, 18H, CH3), 2.58 (s, 18H, CH3), 2.42-2.45 (m, 18H, CH3), 2.22 (s, 18H, CH3), 1.94-2.00 (m, 18H, CH3);  13  C NMR (CDCl3, 100 MHz) δ (ppm) 165.6, 163.5,  160.6, 147.3, 146.9, 136.9, 135.8, 124.3, 118.5, 112.4, 80.4, 77.5, 50.7, 17.5, 15.4, 12.2, 11.4; MALDI-TOF calcd. 1872.5, found 1872.3 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 545.0 (5.77). II-28-4 (tetramer): Yield: 3 mg (5%); 1H NMR (CDCl3, 400 MHz) δ (ppm) 7.21-7.23 (m, 6H, meso-H), 3.80 (d, J = 3.8 Hz, 18H, CH3), 2.58 (t, J = 2.6 Hz, 18H, CH3), 2.41-2.45 (m, 18H, CH3), 2.21 (s, 18H, CH3), 2.01 (d, J = 9.7 Hz, 18H, CH3); MALDI-TOF calcd. 2504.1, found 2504.6 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 544.0 (5.84).  CoII bisdipyrrin complexes (II-29). The same procedure was used as in the synthesis of II-25, starting from II-22 (66 mg, 0.1 mmol) and Co(OAc)2•4H2O (38 mg, 0.15 mmol) to afford dichroic purple/green solids. II-29-3 (trimer): Yield: 4 mg (8%); MALDI-TOF calcd. 1677.7, found 1677.7 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 540.0 (5.54). II-29-4 (tetramer): Yield: 2 mg (4%); MALDI-TOF calcd. 2236.9, found 2236.9 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 541.0 (5.73).  144  NiII bisdipyrrin complexes (II-30). The same procedure was used as in the synthesis of II-25, starting from II-22 (66 mg, 0.1 mmol) and Ni(OAc)2•4H2O (38 mg, 0.15 mmol) to afford dichroic brown/green solids. II-30-3 (trimer): Yield: 4 mg (8%); MALDI-TOF calcd. 1674.7, found 1674.9 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 580.0 (5.40). II-30-4 (tetramer): Yield: 2 mg (3%); MALDI-TOF calcd. 2232.9, found 2233.1 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 582.0 (5.50).  O  N H NC  CN  II-31 2-((4-acetyl-3,5-diethylpyrrol-2-yl)methylene)malononitrile (II-31). According to the previously reported procedure,70 some modifications have been made for synthesis of II-31. To a solution of 2-((3,5-diethylpyrrol-2-yl)methylene)malononitrile (1 g, 5 mmol) in MeNO2 (10 mL) and DCE (10 mL) at 0˚C was slowly added SnCl4 (0.62 mL, 5.3 mmol) and acetyl chloride (0.38 mL, 5.3 mmol). The reaction mixture was stirred for 5 h at room temperature. The mixture was poured into 100 mL water and 100 CH2Cl2, and the organic layer was washed with 10% HCl solution, water, brine and dried over anhydrous Na2SO4. After removal of the organic solvent, the residue was purified by flash chromatography on silica gel, eluting with CH2Cl2, to give a yellow solid. Yield: 0.90 g (75%); 1H NMR (400MHz, CDCl3) δ (ppm) 9.77 (br. s, 1H, NH), 7.50 (s, 1H, CH), 3.06 (q, J = 7.6 Hz, 2H, CH2), 2.86 (q, J = 7.6 Hz, 2H, CH2), 2.51 (s, 3H, 145  CH3), 1.37 (t, J = 7.5 Hz, 3H, CH3), 1.21 (t, J = 7.5 Hz, 3H, CH3); 13C NMR (100MHz, CDCl3) δ (ppm) 194.1, 150.6, 144.4, 141.9, 123.5, 122.7, 116.6, 114.6, 31.0, 22.4, 18.8, 16.8, 11.4; EI MS (M+): m/z 241. HR-EI MS (M+) m/z calcd for C14H15N3O 241.1215, found 241.1214.  N H  CHO  II-32 3,5-diethyl-4-ethynylpyrrole-2-carbaldehyde (II-32). According to the previously reported procedure,71 some modifications have been made for synthesis of II-32. To a solution of DMF (2.5 mL) cooled in an ice-water bath was slowly added POCl3 (0.4 mL, 4 mmol). The reaction mixture was stirred for 30 min, followed by addition of II-31 (0.90 g, 3.73 mmol, dissolved in 10 mL DMF). The mixture was heated to 40˚C and stirred for 3 h. The reaction was poured into a well-stirred 200 mL ice/water to give a precipitate. The precipitate was collected by filtration to give a yellow solid. To the yellow solid (1.06 g, 4.08 mmol) in EtOH (30 mL) was added KOH (2.29 g, 40.8 mmol, dissolved in 5 mL water). The reaction mixture was refluxed for 3 h. The reaction was allowed to cool to room temperature, and was then poured into 100 mL water and 100 mL CH2Cl2. The organic layer was washed with water, brine and dried over anhydrous Na2SO4. After removal of the organic solvent, the residue was purified by flash chromatography on silica gel, eluting with 10% EtOAc in hexanes, to give a white solid. Yield: 0.38 g (53%); 1H NMR (400MHz, CDCl3) δ (ppm) 9.92 (br. s, 1H, NH), 9.52 (s, 1H, CHO), 3.21 (s, 1H, CH), 2.76 – 2.85 (m, 4H), 1.28 – 1.32 (m, 6H); 13C NMR (100MHz, CDCl3) 146  δ (ppm) 176.6, 147.7, 143.0, 126.9, 104.2, 81.2, 20.3, 18.0, 16.2, 12.7; EI MS (M+): m/z 175. HR-EI MS (M+) m/z calcd for C11H13NO 175.0997, found 175.0996.  CHO  HN  NH  OHC  II-33 4,4'-(buta-1,3-diyne-1,4-diyl)bis(3,5-diethyl-1H-pyrrole-2-carbaldehyde)  (II-33).  According to the previously reported procedure,65 some modifications have been made for synthesis of II-33. To a mixture of II-32 (298 mg, 1.7mmol), Pd(PPh3)2Cl2 (120 mg, 0.17mmol) and α-chloroacetone (0.6 mL, 7.8 mmol) in THF (20 mL) was added NEt3 (1 mL). The mixture was stirred for 1 h at room temperature. After addition of CuI (50 mg, 0.26 mmol), the reaction mixture was stirred overnight. After removal of the organic solvent, the residue was purified by flash chromatography on silica gel, eluting with 1% MeOH in CH2Cl2, to give a yellow solid. Yield: 143 mg (48%); 1H NMR (400MHz, DMSO-d6) δ (ppm) 12.08 (br. s, 2H, NH), 9.55 (s, 2H, CHO), 2.76 (q, J = 7.6 Hz, 4H, CH2), 2.67 (q, J = 7.6 Hz, 4H, CH2), 1.20 (t, J = 7.6 Hz, 6H, CH3), 1.19 (t, J = 7.6 Hz, 6H, CH3);  13  C NMR (100MHz, DMSO-d6) δ (ppm) 177.4, 148.5,  141.0, 127.0, 102.1, 77.4, 75.2, 19.8, 17.6, 16.2, 13.4; EI MS (M+): m/z 348. HR-EI MS (M+) m/z calcd for C22H24N2O2 348.1838, found 348.1843.  147  N  HN NH  N  2HBr  II-34 bisdipyrrin ligand (II-34). The same procedure was used as in the synthesis of II-22, starting from II-33 (118 mg, 0.34 mmol) and II-18 (0.09 mL, 0.68 mmol) to give a dark red solid. Yield: 200 mg (82%); 1H NMR (400MHz, CDCl3) δ (ppm) 13.46 (br. s, 2H, NH), 13.12 (br. s, 2H, NH), 7.08 (s, 2H, meso-H), 3.18 (q, J = 7.6 Hz, 4H, CH2), 2.83 (q, J = 7.6 Hz, 4H, CH2), 2.73 (s, 6H, CH3), 2.46 (q, J = 7.6 Hz, 4H, CH2), 2.31 (s, 6H, CH3), 1.46 (t, J = 7.4 Hz, 6H, CH3), 1.31 (t, J = 7.6 Hz, 6H, CH3), 1.09 (t, J = 7.6 Hz, 6H, CH3);  13  C NMR (100MHz,  CDCl3) δ (ppm) 161.7, 159.4, 152.3, 143.8, 132.6, 128.1, 123.6, 119.3, 108.3, 79.9, 74.1, 21.2, 19.6, 17.2, 16.2, 14.2, 13.8, 13.2, 10.1; ESI MS (M+H)+: m/z 559.6; HR-ESI MS (M+H)+: m/z calcd for C38H47N4: 559.3801; found: 559.3802. UV/Vis (CHCl3) λmax nm (logε): 529.0 (5.17).  ZnII bisdipyrrin complexes (II-35). The same procedure was used as in the synthesis of II-25, starting from II-34 (72 mg, 0.1 mmol) to afford dichroic red/green solids. II-35-3 (trimer): Yield: 7 mg (12%); 1H NMR (300MHz, CDCl3) δ (ppm) 6.97 (s, 6H, meso-H), 2.75-2.81 (m, 12H, CH2), 2.24-2.38 (m, 42H, CH2 and CH3), 2.00 (s, 18H, CH3), 1.23-1.33 (m, 30H, CH2 and CH3), 0.99-1.04 (m, 18H, CH3), 0.74 (ddt, J = 12.7, 6.3 and 1.7 Hz, 18H, CH3); 13  C NMR (100MHz, CDCl3) δ (ppm) 165.1, 160.6, 149.0, 139.7, 137.4, 133.1, 131.8, 121.2,  107.4, 79.6, 77.8, 23.7, 19.4, 17.9, 16.5, 14.8, 13.2, 13.0, 9.9; MALDI-TOF calcd. 1860.9, found 1860.8 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 546.0 (5.82). 148  II-35-4 (tetramer): Yield: 8 mg (13%); 1H NMR (300MHz, CDCl3) δ (ppm) 6.97 (s, 8H, meso-H), 2.75-2.81 (m, 16H, CH2), 2.33-2.36 (m, 32H, CH2), 2.23 (s, 24H, CH3), 1.95 (s, 24H, CH3), 1.24-1.33 (m, 40H, CH2 and CH3), 1.01 (dt, J = 7.4 and 3.1 Hz, 24H, CH3), 0.78 (q, J = 7.2 Hz, 24H, CH3); 13C NMR (75MHz, CDCl3) δ (ppm) 164.5, 149.4, 139.2, 137.5, 132.9, 131.9, 121.2, 107.0, 79.5, 77.2, 29.7, 23.7, 19.4, 17.9, 16.5, 14.9, 14.7, 13.3, 9.9; MALDI-TOF calcd. 2481.1, found 2481.1 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 543.0 (5.93).  CoII bisdipyrrin complexes (II-36). The same procedure was used as in the synthesis of II-29, starting from II-34 (72 mg, 0.1 mmol) to afford dichroic purple/green solids. II-36-3 (trimer): Yield: 15 mg (24%); MALDI-TOF calcd. 1845.9, found 1846.0 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 544.0 (5.66); Anal. Calcd. for: C114H132Co3N12: C, 74.13; H, 7.20; N, 9.10. Found: C, 74.06; H, 7.31; N, 9.16. II-36-4 (tetramer): Yield: 7  mg (12%); MALDI-TOF calcd. 2461.2, found 2461.4 [(M)+];  UV/Vis (CHCl3) λmax nm (logε): 541.0 (5.74).  N H  CHO  III-2 4-t-pentylpyrrole-2-carbaldehyde  (III-2).  According  to  the  previously  reported  procedure,74 some modifications have been made for synthesis of III-2. To a suspension of anhydrous AlCl3 (1.6 g, 12 mmol) in DCE (3 mL) cooled to 0˚C was added pyrrole-2-carbaldehyde (0.95 g, 10 mmol). The reaction mixture was stirred for 20 min, 149  followed by addition of 2-chloro-2-methylbutane (1.6 mL, 13 mmol). The mixture was stirred for 4 h at room temperature before being poured into a well-stirred mixture of 200 ml water and 50 mL CH2Cl2. The organic layer was washed with water, saturated NaHCO3, brine and concentrated to give a dark brown oil. The crude oil was purified by flash chromatography on silica gel, eluting with 10% EtOAc in hexanes, to give a brown oil. Yield: 1.1 g (67%); 1H NMR (300MHz, CDCl3) δ (ppm) 10.30 (br. s, 1H, NH), 9.44 (s, 1H, CHO), 7.03 (s, 1H, Ar-H), 6.91 (d, J = 1.3 Hz, 1H, Ar-H), 1.21 - 1.31 (m, 11H, CH2 CH3);  13  C NMR (75MHz, CDCl3) δ (ppm)  179.2, 132.4, 123.1, 119.0, 111.3, 36.9, 31.6, 28.6; EI MS (M+): m/z 165. HR-EI MS (M+) m/z calcd for C10H15NO 165.1154, found 165.1152. I  N Ts  CHO  III-3 3-iodo-1-tosylpyrrole-2-carbaldehyde (III-3). III-3 was synthesized based on the previously reported procedure.75 Yield: 6.01 g (42%); 1H NMR (300MHz, CD2Cl2) δ (ppm) 9.78 (s, 1H, CHO), 7.83 (d, J = 8.7 Hz, 2H, Ar-H), 7.66 (d, J = 3.5 Hz, 1H, pyrrole-H), 7.36 (d, J = 7.9 Hz, 2H, Ar-H), 6.63 (d, J = 3.5 Hz, 1H, Pyrrole-H), 2.43 (s, 3H, CH3); EI MS (M+): m/z 375. HR-EI MS (M+) m/z calcd for C12H10INO3S 374.9426, found 374.9420.  150  N Ts  CHO  III-4 3-(3,5-dimethylphenyl)-1-tosylpyrrole-2-carbaldehyde  (III-4).  According  to  the  previously reported procedure,75 some modifications have been made for synthesis of III-4. To a mixture of 3,5-dimethylphenylboronic acid (0.4 g, 2.70 mmol), Pd(PPh3)2Cl2 (77 mg, 0.11 mmol) and III-3 (0.85 g, 2.26 mmol) in DME (35 mL) was added K2CO3 (0.97 g, 7.0 mmol, dissolved in minimum amount of water). The reaction mixture was heated to reflux and stirred for 5 h. The reaction mixture was allowed to cool, and the organic solvent was then removed in vacuo. The residue was treated with EtOAc (100 mL) and thoroughly washed with several portions of water and brine. The organic layer was dried over anhydrous Na2S04 and concentrated under reduced pressure. Flash chromatography on silica gel, eluting with 10% EtOAc in hexanes, afforded an off-white solid. Yield: 0.58 g (73%); 1H NMR (300MHz, CDCl3) δ (ppm) 9.58 (s, 1H, CHO), 7.96 (d, J = 8.4 Hz, 2H, Ar-H), 7.84 (d, J = 3.0 Hz, 1H, pyrrole-H), 7.35 (d, J = 8.4 Hz, 2H, Ar-H), 7.04 (s, 1H, Ar-H), 7.01 (s, 2H, Ar-H), 6.48 (d, J = 3.1 Hz, 1H, pyrrole-H), 2.44 (s, 3H, CH3), 2.14 (s, 6H, CH3); 13C NMR (75MHz, CDCl3) δ (ppm) 178.4, 145.3, 144.3, 138.2, 135.3, 132.2, 130.4, 129.7, 129.6, 128.5, 128.1, 127.4, 112.8, 21.7, 21.2; EI MS (M+): m/z 353. HR-EI MS (M+) m/z calcd for C20H19NO3S 353.1086, found 353.1085.  151  C9H19  N Ts  CHO  III-5 3-(4-nonylphenyl)-1-tosylpyrrole-2-carbaldehyde (III-5). The same procedure was used as in the synthesis of III-4, starting from 4-nonylphenylboronic acid (0.67 g, 2.70 mmol) to afford a yellow oil. Yield: 0.80 g (78%); EI MS (M+): m/z 451. HR-EI MS (M+) m/z calcd for C27H33NO3S 451.2181, found 451.2195.  N H  CHO  III-6 3-(3,5-dimethylphenyl)pyrrole-2-carbaldehyde (III-6).  According to the previously  reported procedure,75 some modifications have been made for synthesis of III-6. To a solution of III-4 (0.47 g, 1.33 mmol) in THF (20 mL) and MeOH (15 mL) was added KOH (0.37 g, 6.65 mmol). The reaction mixture was heated to 60˚C and stirred for 1 h. The mixture was allowed to cool, and the organic solvent was then removed in vacuo. The residue was treated with EtOAc (100 mL) and thoroughly washed with several portions of water and brine. The organic layer was dried over anhydrous Na2SO4 and concentrated under reduced pressure. Flash chromatography on silica gel, eluting with 20% EtOAc in hexanes, gave a brown solid. Yield: 0.23 g (87%); 1H NMR (300MHz, CDCl3) δ (ppm) 9.79 (br. s, 1H, NH), 9.65 (s, 1H, CHO), 7.13 (s, 3H, Ar-H), 7.04 (s, 1H, Ar-H), 6.44 (t, J = 2.4 Hz, 1H, pyrrole-H), 2.39 (s, 6H, CH3); 152  13  C NMR (75MHz, CDCl3) δ (ppm) 180.0, 138.3, 137.4, 133.5, 129.4, 128.8, 127.1, 125.4,  111.5, 21.3; EI MS (M+): m/z 199. HR-EI MS (M+) m/z calcd for C13H13NO 199.0997, found 199.0997. C9H19  CHO  N H  III-7 3-(4-nonylphenyl)pyrrole-2-carbaldehyde (III-7). The same procedure was used as in the synthesis of III-6, starting from III-5 (0.38 g, 0.84 mmol) and KOH (0.24 g, 4.2 mmol) to afford a brown solid. Yield: 0.23 g (92%); EI MS (M+): m/z 297. HR-EI MS (M+) m/z calcd for C20H27NO 297.2093, found 297.2094.  I  N H  CO2Et  III-8 ethyl 3-ethyl-5-iodo-4-methylpyrrole-2-carboxylate (III-8). III-8 was synthesized based on the previously reported procedure.99 1H NMR (300MHz, CDCl3) δ (ppm) 8.77 (br. s, 1H, NH), 4.32 (q, J = 7.2 Hz, 2H, CH2), 2.78 (q, J = 7.4 Hz, 2H, CH2), 1.99 (s, 3H, CH3), 1.36 (t, J = 7.0 Hz, 3H, CH3), 1.11 (t, J = 7.4 Hz, 3H, CH3); EI MS (M+): m/z 307. HR-EI MS (M+) m/z calcd for C10H14INO2 307.0069, found 307.0059.  153  N H  CO2Et  III-9  ethyl 5-(3,5-dimethylphenyl)-3-ethyl-4-methylpyrrole-2-carboxylate (III-9). According to the previously reported procedure,100 some modifications have been made for synthesis of III-9. To a mixture of III-8 (1.0 g, 3.26 mmol), 3,5-dimethylphenylboronic acid (0.6 g, 4 mmol) and Pd(PPh3)2Cl2 (140 mg, 0.2 mmol) in DME (30 mL) was added K2CO3 (1.38 g, 10 mmol, dissolved in minimum amount of water). The mixture was heated to 85˚C and stirred for 3 h. The reaction was allowed to cool, and the organic solvent was then removed in vacuo. The residue was treated with EtOAc (100 mL) and thoroughly washed with several portions of water and brine. The organic layer was dried over anhydrous Na2SO4 and concentrated under reduced pressure. Flash chromatography on silica gel, eluting with 20% EtOAc in hexanes, afforded a yellow solid. Yield: 0.85 g (92%); 1H NMR (300MHz, CDCl3) δ (ppm) 8.81 (br. s, 1H, NH), 7.10 (s, 2H, Ar-H), 6.99 (s, 1H, Ar-H), 4.35 (q, J = 7.1 Hz, 2H, CH2), 2.83 (q, J = 7.4 Hz, 2H, CH2), 2.38 (s, 6H, CH3), 2.17 (s, 3H, CH3), 1.39 (t, J = 7.3 Hz, 3H, CH3), 1.19 (t, J = 7.5 Hz, 3H, CH3); 13C NMR (75MHz, CDCl3) δ (ppm) 161.6, 138.3, 134.6, 133.1, 132.4, 129.1, 125.1, 117.8, 116.9, 59.8, 21.3, 18.4, 15.0, 14.5, 9.8; EI MS (M+): m/z 285. HR-EI MS (M+) m/z calcd for C18H23NO2 285.1729, found 285.1730.  154  CO2Et  N H  III-10 ethyl 3-ethyl-4-methyl-5-phenylpyrrole-2-carboxylate (III-10). The same procedure was used as in the synthesis of III-9, starting from phenylboronic acid (0.49 g, 4 mmol) to afford a yellow solid. Yield: 0.59 g (70%); 1H NMR (300MHz, CD2Cl2) δ (ppm) 8.86 (br. s, 1H, NH), 7.31 - 7.50 (m, 5H, Ar-H), 4.30 (q, J = 7.0 Hz, 2H, CH2), 2.81 (q, J = 7.0 Hz, 2H, CH2), 2.16 (s, 3H, CH3), 1.36 (t, J = 7.0 Hz, 3H, CH3), 1.15 (t, J = 7.0 Hz, 3H, CH3); EI MS (M+): m/z 257. HR-EI MS (M+) m/z calcd for C16H19NO2 257.1416, found 257.1418.  F  N H  CO2Et  III-11 ethyl 3-ethyl-5-(4-fluorophenyl)-4-methylpyrrole-2-carboxylate (III-11). The same procedure was used as in the synthesis of III-9, starting from 4-fluorophenylboronic acid (0.56 g, 4 mmol) to afford an off-white solid. Yield: 0.78 g (87%); 1H NMR (300MHz, CDCl3) δ (ppm) 8.92 (br. s, 1H, NH), 7.42 - 7.46 (m, 2H, Ar-H), 7.13 (t, J = 8.8 Hz, 2H, Ar-H), 4.32 (q, J = 7.1 Hz, 2H, CH2), 2.81 (q, J = 7.6 Hz, 2H, CH2), 2.14 (s, 3H, CH3), 1.37 (t, J = 7.1 Hz, 3H, CH3), 1.18 (t, J = 7.5 Hz, 3H, CH3); 13C NMR (75MHz, CDCl3) δ (ppm) 163.7, 161.6, 160.4, 134.5, 129.1, 129.0, 117.0, 115.9, 115.6, 59.9, 18.5, 15.0, 14.5, 9.6; EI MS (M+): m/z 275. HR-EI MS 155  (M+) m/z calcd for C16H18NO2F 275.1322, found 275.1321.  N H  COOH  III-12  5-(3,5-dimethylphenyl)-3-ethyl-4-methylpyrrole-2-carboxylic acid (III-12). According to the previously reported procedure,100 some modifications have been made for synthesis of III-12. To a solution of III-9 (0.71 g, 2.5 mmol) in EtOH (30 mL) was added KOH (1.4 g, 25 mmol, dissolved in 5 mL water). The reaction mixture was refluxed for 3 h. After removal of the solvent, the residue was treated with 400 mL water, followed by addition of acetic acid to give a precipitate. The precipitate was filtered and washed with several portions of water to remove excess acetic acid to afford a grey solid. Yield: 0.50 g (78%); 1H NMR (300MHz, CDCl3) δ (ppm) 8.87 (s, 1H, COOH), 7.11 (s, 2H, Ar-H), 7.01 (s, 1H, Ar-H), 2.86 (q, J = 7.6 Hz, 2H, CH2), 2.38 (s, 6H, CH3), 2.18 (s, 3H, CH3), 1.20 (t, J = 7.4 Hz, 3H, CH3); 13C NMR (75MHz, CDCl3) δ (ppm) 166.3, 138.4, 136.8, 134.6, 132.2, 132.1, 129.4, 125.2, 117.5, 21.3, 18.4, 15.0, 9.8; EI MS (M+): m/z 257. HR-EI MS (M+) m/z calcd for C16H19NO2 257.1416, found 257.1417.  156  COOH  N H  III-13 3-ethyl-4-methyl-5-phenylpyrrole-2-carboxylic acid (III-13). The same procedure was used as in the synthesis of III-12, starting from III-10 (0.64 g, 2.5 mmol) to afford a grey solid. Yield: 0.44 g (76%); 1H NMR (300MHz, CDCl3) δ (ppm) 9.00 (s, 1H, COOH), 7.40 - 7.48 (m, 5H, Ar-H), 2.84 (q, J = 7.5 Hz, 2H, CH2), 2.17 (s, 3H, CH3), 1.18 (t, J = 7.5 Hz, 3H, CH3); 13C NMR (75MHz, CDCl3) δ (ppm) 166.2, 136.4, 133.9, 128.7, 127.5, 127.3, 125.5, 117.5, 117.4, 18.4, 15.0, 9.8; EI MS (M+): m/z 229. HR-EI MS (M+) m/z calcd for C14H15NO2 229.1103, found 229.1103.  F  COOH  N H  III-14 3-ethyl-5-(4-fluorophenyl)-4-methylpyrrole-2-carboxylic  acid  (III-14).  The  same  procedure was used as in the synthesis of III-12, starting from III-11 (0.69 g, 2.5 mmol) to afford a grey solid. Yield: 0.57 g (92%); 1H NMR (300MHz, CDCl3) δ (ppm) 8.96 (s, 1H, COOH), 7.43 - 7.48 (m, 2H, Ar-H), 7.14 (t, J = 8.8 Hz, 2H, Ar-H), 2.86 (q, J = 7.5 Hz, 2H, CH2), 2.15 (s, 3H, CH3), 1.20 (t, J = 7.5 Hz, 3H, CH3);  13  C NMR (75MHz, CDCl3) δ (ppm) 166.5,  163.9, 160.6, 136.9, 129.2, 129.1, 117.6, 116.0, 115.7, 18.4, 15.0, 9.7; EI MS (M+): m/z 247. HR-EI MS (M+) m/z calcd for C14H14NO2F 247.1009, found 247.1008. 157  N H  CHO  III-15  5-(3,5-dimethylphenyl)-3-ethyl-4-methylpyrrole-2-carbaldehyde (III-15). According to the previously reported procedure,76 some modifications have been made for synthesis of III-15. To a 50 mL round-bottom flask was added III-12 (0.42 g, 1.65 mmol) and TFA (3 mL). The reaction mixture was stirred for 15 mins before cooling to 0˚C. The mixture was stirred for an additional 15 mins after slow addition of TMOF (2 mL) at 0˚C. The reaction was poured into a well-stirred mixture of ice-water and CH2Cl2. The organic layer was washed with water, saturated NaHCO3 and brine, dried over anhydrous Na2SO4 and filtered. After removal of the organic solvent, the residue was purified by flash chromatography on silica gel, eluting with 30% EtOAc in hexanes, to give an off-white solid. Yield: 0.36 g (90%); 1H NMR (300MHz, CDCl3) δ (ppm) 9.62 (s, 1H, CHO), 9.11 (br. s, 1H, NH), 7.13 (s, 2H, Ar-H), 7.02 (s, 1H, Ar-H), 2.78 (q, J = 7.6 Hz, 2H, CH2), 2.37 (s, 6H, CH3), 2.18 (s, 3H, CH3), 1.26 (t, J = 7.7 Hz, 3H, CH3);  13  C NMR (75MHz, CDCl3) δ (ppm) 176.8, 139.1, 138.4, 137.3, 131.6, 129.9, 128.1,  125.2, 117.6, 21.3, 17.2, 16.5, 9.7; EI MS (M+): m/z 241. HR-EI MS (M+) m/z calcd for C16H19NO 241.1467, found 241.1467.  158  CHO  N H  III-16 3-ethyl-4-methyl-5-phenylpyrrole-2-carbaldehyde (III-16). The same procedure was used as in the synthesis of III-15, starting from III-13 (0.38 g, 1.65 mmol) to afford an off-white solid. Yield: 0.28 g (80%); 1H NMR (300MHz, CDCl3) δ (ppm) 9.64 (s, 1H, CHO), 9.24 (br. s, 1H, NH), 7.35 - 7.53 (m, 5H, Ar-H), 2.79 (q, J = 7.4 Hz, 2H, CH2), 2.19 (s, 3H, CH3), 1.27 (t, J = 7.7 Hz, 3H, CH3);  13  C NMR (75MHz, CDCl3) δ (ppm) 176.9, 139.1, 137.0, 131.7, 128.8,  128.3, 128.1, 127.4, 117.7, 17.2, 16.5, 9.7; EI MS (M+): m/z 213. HR-EI MS (M+) m/z calcd for C14H15NO 213.1154, found 213.1155.  F  N H  CHO  III-17 3-ethyl-5-(4-fluorophenyl)-4-methylpyrrole-2-carbaldehyde  (III-17).  The  same  procedure was used as in the synthesis of III-15, starting from III-14 (0.41 g, 1.65 mmol) to afford a yellow solid. Yield: 0.35 g (92%); 1H NMR (300MHz, CDCl3) δ (ppm) 9.62 (s, 1H, CHO), 9.41 (br. s, 1H, NH), 7.46 - 7.52 (m, 2H, Ar-H), 7.15 (t, J = 8.6 Hz, 2H, Ar-H), 2.78 (q, J = 7.6 Hz, 2H, CH2), 2.15 (s, 3H, CH3), 1.26 (t, J = 7.6 Hz, 3H, CH3); 13C NMR (75MHz, CDCl3) δ (ppm) 176.9, 164.1, 160.9, 139.2, 136.2, 129.4, 129.3, 116.0, 115.7, 17.2, 16.5, 9.6; EI MS (M+): m/z 231. HR-EI MS (M+) m/z calcd for C14H14NOF 231.1059, found 231.1059. 159  CO2CH2Ph  PhH2CO2C  NH  HN  III-18 dihydropyrrolo[3,2-e]indole (III-18).  III-18 was synthesized based on the previously  reported procedure to afford an off-white solid.77 Yield: 9.0 g (36%); 1H NMR (300MHz, DMSO-d6) δ (ppm) 11.55 (br. s, 2H, NH), 7.32 - 7.46 (m, 10H, Ar-H), 5.27 (s, 4H, CH2), 2.70 (s, 4H, CH2), 2.46 (s, 6H, CH3); EI MS (M+): m/z 454; Anal. Calcd. for: C28H26N2O4: C, 73.99; H, 5.77; N, 6.16. Found: C, 74.39; H, 5.87; N, 6.50.  N  HN  NH  N  2HBr  III-20 bisdipyrrin ligand (III-20). According to the previously reported procedure,46 some modifications have been made for synthesis of III-20. To a mixture of III-18 (227 mg, 0.50 mmol) and 10 mol % palladium on activated carbon (50 mg) in a 250 mL round-bottom flask was added THF (75 mL) and MeOH (25 mL). The mixture was purged with hydrogen at 1 atm and stirred for overnight. The reaction mixture was then filtered through Celite to remove the catalyst. The filtrate was collected in a 250 mL round-bottom flask, and then III-1 (48 mg, 0.50 mmol) was added, followed by the addition of 33% hydrogen bromide in acetic acid (1.0 mL). The solution immediately turned from colourless to dark purple. The solution was stirred for 1 h, 160  and the organic solvent was then removed in vacuo to give black solid. The black solid was redissolved in CHCl3 (75 mL) and MeOH (25 mL), and III-1 (48 mg, 0.50 mmol) was added, followed by the addition of 33% hydrogen bromide in acetic acid (1.0 mL). The reaction mixture was stirred for 4 h at room temperature. Removal of the solvent in vacuo gave the crude product. To this crude product was added just enough chloroform and methanol to form a homogeneous solution, and then diethyl ether was added to precipitate the product, which was collected by filtration and rinsed with more diethyl ether to give a black solid. Yield: 200 mg (80%); ESI MS (M+H)+: m/z 341.3; HR-ESI MS (M+H)+: m/z calcd for C22H21N4: 341.1766; found: 341.1758. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 583.0 (1.115).  N  HN  NH  N  2HBr  III-21 bisdipyrrin ligand (III-21). The same procedure was used as in the synthesis of III-20, starting from III-2 (83 mg, 0.5 mmol) to afford a black solid. Yield: 275 mg (86%); ESI MS (M+H)+: m/z 481.4; HR-ESI MS (M+H)+: m/z calcd for C32H41N4: 481.3331; found: 481.3338. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 598.0 (0.837).  161  N  HN  NH  N  2HBr  III-22 bisdipyrrin ligand (III-22). The same procedure was used as in the synthesis of III-20, starting from III-6 (100 mg, 0.5 mmol) to afford a black solid. Yield: 300 mg (84%); ESI MS (M+H)+: m/z 549.5; HR-ESI MS (M+H)+: m/z calcd for C38H37N4: 549.3018; found: 549.3026. UV/Vis (CHCl3) λmax nm (A): 608 (0.607) and 668.0 (0.564).  C9H19  C9H19  N  HN  NH  N  2HBr  III-23 bisdipyrrin ligand (III-23). The same procedure was used as in the synthesis of III-20, starting from III-7 (149 mg, 0.5 mmol) to afford a dark brown solid. Yield: 150 mg (36%); 1H NMR (400MHz, CDCl3) δ (ppm) 14.20 (br. s, 2H, NH), 13.56 (br. s, 2H, NH), 7.82 (s, 2H, pyrrole-H), 7.45 (s, 2H, meso-H), 7.37 (dd, J = 15.7, 7.8 Hz, 8H, Ar-H), 6.65 (s, 2H, pyrrole-H), 3.55 (s, 4H, CH2), 2.70 (t, J = 7.8 Hz, 4H, CH2), 2.50 (s, 6H, CH3), 1.69 (t, J = 6.6 Hz, 4H, CH2), 1.29 (s, 24H, CH2), 0.89 (t, J = 6.0 Hz, 6H, CH3); 13C NMR (100MHz, CDCl3) δ (ppm) 159.4, 149.1, 144.7, 139.5, 137.6, 130.4, 129.8, 129.6, 129.3, 126.0, 125.7, 121.4, 114.9, 35.8, 31.9, 162  31.3, 29.5, 29.5, 29.4, 29.3, 22.7, 22.2, 14.1, 13.4; ESI MS (M+H)+: m/z 745.5; HR-ESI MS (M+H)+: m/z calcd for C52H65N4: 745.5209; found: 745.5229. UV/Vis (CHCl3) λmax nm (A): 607.0 (1.082).  N  HN  NH  N  2HBr  III-24  bisdipyrrin ligand (III-24). The same procedure was used as in the synthesis of III-20, starting from III-15 (121 mg, 0.5 mmol) to afford a black solid. Yield: 346 mg (87%); 1H NMR (400MHz, CDCl3) δ (ppm) 14.27 (br. s, 2H, NH), 12.52 (br. s, 2H, NH), 7.56 (s, 4H, Ar-H), 7.28 (s, 2H, Ar-H), 7.14 (s, 2H, meso-H), 3.50 (s, 4H, CH2), 2.78 (d, J = 7.0 Hz, 4H, CH2), 2.65 (s, 6H, CH3), 2.44 (s, 12H, CH3), 2.20 (s, 6H, CH3), 1.24 (t, J = 7.6 Hz, 6H, CH3);  13  C NMR  (100MHz, CDCl3) δ (ppm) 156.0, 154.8, 150.4, 138.1, 134.3, 132.8, 128.1, 128.0, 127.8, 126.9, 123.5, 120.8, 119.3, 29.6, 22.2, 21.3, 18.9, 16.2, 10.7; ESI MS (M+H)+: m/z 633.6; HR-ESI MS (M+H)+: m/z calcd for C44H49N4: 633.3957; found: 633.3943. UV/Vis (CHCl3) λmax nm (logε): 647.0 (5.24).  163  N  HN  NH  N  2HBr  III-25 bisdipyrrin ligand (III-25). The same procedure was used as in the synthesis of III-20, starting from III-16 (107 mg, 0.5 mmol) to afford a black solid. Yield: 300 mg (81%); 1H NMR (400MHz, CDCl3) δ (ppm) 14.25 (br. s, 2H, NH), 12.55 (br. s, 2H, NH), 7.91 (d, J = 6.5 Hz, 4H, Ar-H), 7.51 - 7.56 (m, 6 H, Ar-H), 7.34 (s, 2H, meso-H), 3.48 (s, 4H, CH2), 2.76 (q, J = 7.6 Hz, 4H, CH2), 2.67 (s, 6H, CH3), 2.17 (s, 6H, CH3), 1.20 (t, J = 7.1 Hz, 6H, CH3);  13  C NMR  (100MHz, CDCl3) δ (ppm) 156.2, 154.0, 150.7, 134.8, 130.8, 130.1, 128.5, 128.4, 128.1, 126.9, 123.4, 120.8, 120.0, 22.1, 18.7, 16.1, 13.6, 10.6; ESI MS (M+H)+: m/z 577.5; HR-ESI MS (M+H)+: m/z calcd for C40H41N4: 577.3331; found: 577.3329. UV/Vis (CHCl3) λmax nm (logε): 644 (5.21).  N  HN  NH  N  2HBr F  III-26  F  bisdipyrrin ligand (III-26). The same procedure was used as in the synthesis of III-20, starting from III-17 (116 mg, 0.5 mmol) to afford a black solid. Yield: 350 mg (90%); 1H NMR (400MHz, CDCl3) δ (ppm) 14.25 (br. s, 2H, NH), 12.61 (br. s, 2H, NH), 7.93 (s, 4H, Ar-H), 7.32 164  (s, 2H, meso-H), 7.22 (t, J = 7.6 Hz, 4H, Ar-H), 3.48 (s, 4H, CH2), 2.77 (d, J = 5.9 Hz, 4H, CH2), 2.66 (s, 6H, CH3), 2.16 (s, 6H, CH3), 1.23 (br. s, 6H, CH3); 13C NMR (100MHz, CDCl3) δ (ppm) 156.5, 152.9, 150.6, 134.9, 132.4, 132.3, 128.2, 126.8, 124.6, 123.3, 119.9, 116.0, 115.7, 22.2, 18.8, 16.1, 13.6, 10.6; ESI MS (M+H)+: m/z 613.5; HR-ESI MS (M+H)+: m/z calcd for C40H39N4F2: 613.3143; found: 613.3148. UV/Vis (CHCl3) λmax nm (logε): 644.0 (5.31).  ZnII bisdipyrrin complex (III-27-4). According to the previously reported procedure,67 some modifications have been made for synthesis of III-27-4. To a solution of III-20 (50 mg, 0.1 mmol) in CHCl3/MeOH (20 mL/10 mL) was added a solution of Zn(OAc)2 ⋅2H2O (33 mg, 0.15 mmol) in MeOH (1 mL), followed by addition of a solution of NaOAc (82 mg, 1 mmol) in MeOH (1 mL). After stirring overnight, the solvent was removed by rotary evaporation. The crude compound was purified by flash chromatography on silica gel, eluting with CH2Cl2, to give the target ZnII complex as a dark green solid. Yield: 8 mg (19%); 1H NMR (300MHz, CDCl3) δ (ppm) 7.18 (s, 8H, pyrrole-H), 7.16 (s, 8H, pyrrole-H), 6.99 (d, J = 3.5 Hz, 8H, meso-H), 6.34 (dd, J = 3.7, 1.4 Hz, 8H, pyrrole-H), 2.53 (s, 24H, CH3), 2.28 (dq, J = 10.6, 6.6 Hz, 16H, CH2);  13  C NMR (75MHz, CDCl3) δ (ppm) 164.2, 145.4, 140.1, 138.0, 133.7, 128.4,  126.7, 123.4, 115.3, 25.0, 13.1; MALDI-TOF calcd. 1615.2, found 1615.2 [(M)+]; Anal. Calcd. for: C88H72N16Zn4: C, 65.44; H, 4.49; N, 13.88. Found: C, 65.33; H, 4.59; N, 13.63; UV/Vis (CHCl3) λmax nm (logε): 575.0 (5.63) and 613.0 (5.53).  165  CoII bisdipyrrin complex (III-28-4). The same procedure was used as in the synthesis of III-27-4, starting from III-20 (50 mg, 0.1 mmol) and Co(OAc)2•4H2O (38 mg, 0.15 mmol) to afford a dark purple solid. Yield: 9 mg (21%); MALDI-TOF calcd. 1589.4, found 1589.4 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 570.0 (1.011) and 645.0 (0.842).  ZnII bisdipyrrin complex (III-29-4). The same procedure was used as in the synthesis of III-27-4, starting from III-21 (64 mg, 0.1 mmol) to afford a dark green solid. Yield: 9 mg (17%); Anal. Calcd. for: C128H152N16Zn4: C, 70.64; H, 7.04; N, 10.30. Found: C, 70.41; H, 7.24; N, 10.00; UV/Vis (CHCl3) λmax nm (logε): 590.0 (5.60) and 629.0 (5.56).  NiII bisdipyrrin complex (III-30-4). The same procedure was used as in the synthesis of III-27-4, starting from III-21 (64 mg, 0.1 mmol) and Ni(OAc)2•4H2O (38 mg, 0.15 mmol) to afford a dark brown solid. Yield: 3 mg (5%); Anal. Calcd. for: C128H152N16Ni4: C, 71.52; H, 7.13; N, 10.43. Found: C, 71.78; H, 7.29; N, 10.32; UV/Vis (CHCl3) λmax nm (logε): 615.0 (5.67) and 658.0 (5.58).  ZnII bisdipyrrin complex (III-31-4). The same procedure was used as in the synthesis of III-27-4, starting from III-22 (71 mg, 0.1 mmol). The crude compound collected from flash chromatography on silica gel, was then purified using gel permeation chromatography eluting with toluene. The target ZnII complex was obtained as a dark green solid. Yield: 7 mg (11%); 1H NMR (300MHz, CD2Cl2) δ (ppm) 7.34 (s, 8H, Ar-H), 7.16 (d, J = 0.8 Hz, 8H, Pyrrole-H), 7.11 (s, 16H, Ar-H), 7.01 (s, 8H, meso-H), 6.41 (d, J = 1.5 Hz, 8H, Pyrrole-H), 2.46 (s, 24H, CH3), 166  2.38 (s, 64H, CH2 and CH3);  13  C NMR (75MHz, CD2Cl2) δ (ppm) 164.8, 144.5, 144.1, 141.0,  138.7, 136.5, 135.8, 134.5, 129.1, 127.6, 126.5, 124.2, 115.2, 30.3, 25.9, 21.7, 13.4; MALDI-TOF calcd. 2448.4, found 2448.5 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 593.0 (5.58) and 632.0 (5.56).  ZnII bisdipyrrin complex (III-32-4). The same procedure was used as in the synthesis of III-31-4, starting from III-23 (83 mg, 0.1 mmol) to afford a dark green solid. Yield: 10 mg (13%); 1H NMR (300MHz, CD2Cl2) δ (ppm) 6.88-7.50 (m, 48H), 6.40 (s, 8H, Pyrrole-H), 2.67 (s, 16H, CH2), 2.41-2.45 (m, 24H, CH3), 1.27-1.38 (m, 128H, CH2), 0.89-0.91 (m, 24H, CH3); 13  C NMR (100MHz, CDCl3) δ (ppm) 163.9, 144.4, 143.5, 141.7, 140.4, 135.3, 133.5, 129.1,  128.6, 126.0, 123.4, 114.7, 35.8, 31.9, 31.5, 29.7, 29.6, 29.6, 29.4, 25.2, 22.7, 14.1, 13.2; MALDI-TOF calcd. 3233.9, found 3233.9 [(M)+]; Anal. Calcd. for: C208H248N16Zn4: C, 77.25; H, 7.73; N, 6.93. Found: C, 77.14; H, 7.91; N, 6.68; UV/Vis (CHCl3) λmax nm (logε): 594.0 (5.64) and 632.0 (5.63).  ZnII bisdipyrrin complex (III-33-4). The same procedure was used as in the synthesis of III-31-4, starting from III-24 (79 mg, 0.1 mmol) to afford a dark green solid. Yield: 5 mg (7%); 1  H NMR (400MHz, CDCl3) δ (ppm) 6.74 (s, 8H, meso-H), 6.63 (s, 8H, Ar-H), 6.57 (s, 16H,  Ar-H), 2.50-2.58 (m, 16H, CH2), 2.45 (s, 24H, CH3), 2.14-2.20 (m, 16H, CH2), 1.99 (s, 48H, CH3), 1.88 (s, 24H, CH3), 1.13 (t, J = 7.6 Hz, 24H, CH3); 13C NMR (100MHz, CDCl3) δ (ppm) 160.7, 157.2, 142.9, 138.3, 136.6, 135.7, 129.5, 128.3, 126.0, 122.6, 121.1, 120.5, 29.7, 25.3, 21.1, 18.4, 16.1, 13.0, 10.1; MALDI-TOF calcd. 2785.0, found 2784.7 [(M)+]; UV/Vis (CHCl3) 167  λmax nm (logε): 625.0 (5.68) and 661.0 (5.66).  ZnII bisdipyrrin complexes (III-34). The same procedure was used as in the synthesis of III-31-4, starting from III-25 (74 mg, 0.1 mmol) to afford dark green solids. III-34-4 (grid): Yield: 6 mg (10%); 1H NMR (400MHz, CDCl3) δ (ppm) 6.90-7.02 (m, 40H, Ar-H), 6.74 (s, 8H, meso-H), 2.53-2.64 (m, 16H, CH2), 2.43 (s, 24H, CH3), 2.11 (d, J = 4.1 Hz, 16H, CH2), 1.90 (s, 24H, CH3), 1.16 (t, J = 7.6 Hz, 24H, CH3); 13C NMR (100MHz, CDCl3) δ (ppm) 161.1, 156.5, 143.4, 138.6, 135.8, 135.6, 130.2, 128.0, 127.3, 126.3, 122.8, 121.0, 29.7, 25.2, 18.4, 16.6, 12.9, 10.2; MALDI-TOF calcd. 2560.6, found 2560.8 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 623.0 (5.69) and 659.0 (5.67). III-34-6 (hexamer): Yield: 1 mg (1%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.02 (dd, J = 8.7 and 1.5 Hz, 24H, Ar-H), 6.97 (d, J = 7.0 Hz, 12H, Ar-H), 6.88 (t, J = 7.4 Hz, 24H, Ar-H), 6.73 (s, 12H, meso-H), 2.62-2.70 (m, 24H, CH2), 2.27 (s, 36H, CH3), 1.88-2.00 (m, 60H, CH2 and CH3), 1.19 (t, J = 7.4 Hz, 36H, CH3); MALDI-TOF calcd. 3840.9, found 3840.4 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 623.0 (5.88) and 659.0 (5.89).  CoII bisdipyrrin complex (III-35-4). The same procedure was used as in the synthesis of III-31-4, starting from III-25 (74 mg, 0.1 mmol) and Co(OAc)2•4H2O (38 mg, 0.15 mmol) to afford a dark purple solid. Yield: 7 mg (11%); MALDI-TOF calcd. 2533.0, found 2533.0 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 643.0 (5.56) and 692.0 (5.49).  168  ZnII bisdipyrrin complexes (III-36). The same procedure was used as in the synthesis of III-31-4, starting from III-26 (77 mg, 0.1 mmol) to afford dark green solids. III-36-4 (grid): Yield: 6 mg (9%); 1H NMR (400MHz, CDCl3) δ (ppm) 6.88 (dd, J = 7.9 and 5.5 Hz, 16H, Ar-H), 6.81 (s, 8H, meso-H), 6.61 (t, J = 8.6 Hz, 16H, Ar-H), 2.56-2.65 (m, 16H, CH2), 2.49 (s, 24H, CH3), 2.15 (s, 16H, CH2), 1.88 (s, 24H, CH3), 1.17 (t, J = 7.5 Hz, 24H, CH3); 13  C NMR (100MHz, CDCl3) δ (ppm) 161.0, 155.7, 144.0, 138.5, 135.7, 131.6, 130.8, 129.6,  122.8, 121.2, 121.1, 114.3, 114.1, 29.7, 25.3, 18.4, 16.5, 12.8, 10.1; MALDI-TOF calcd. 2704.5, found 2704.3 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 620.0 (5.44) and 657.0 (5.42). III-36-6 (hexamer): Yield: 2 mg (2%); 1H NMR (400MHz, CDCl3) δ (ppm) 6.95 (dd, J = 8.5 and 5.6 Hz, 24H, Ar-H), 6.79 (s, 12H, meso-H), 6.57 (t, J = 8.5 Hz, 24H, Ar-H), 2.69 (q, J = 7.0 Hz, 24H, CH2), 2.32 (s, 36H, CH3), 1.96-1.99 (m, 60H, CH2 and CH3), 1.19 (t, J = 7.6 Hz, 36H, CH3); MALDI-TOF calcd. 4056.8, found 4056.4 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 618.0 (5.59) and 655.0 (5.58).  N H  IV-1 2-methylpyrrole (IV-1). IV-1 was synthesized based on the previously reported procedure, starting with pyrrole-2-carboxaldehyde (9.5 g, 0.10 mol) to afford a colourless liquid.85 Yield: 4.3 g (50%); 1H NMR (400MHz, CD2Cl2) δ (ppm) 7.96 (br. s, 1H, NH), 6.63 (s, 1H, pyrrole-H), 6.08 (d, J = 3.0 Hz, 1H, pyrrole-H), 5.88 (s, 1H, pyrrole-H), 2.28 (s, 3H, CH3);  13  C NMR  (100MHz, CD2Cl2) δ (ppm) 128.0, 116.6, 108.8, 106.3, 13.1; EI MS (M+): m/z 81. 169  NH  N  IV-2 meso-mesityl dipyrrin ligand (IV-2). The same procedure was used as in the synthesis of IV-3, starting with 2,4,6-trimethylbenzaldehyde (222 mg, 1.5 mmol) and IV-1 (260 mg, 3.21 mmol) to afford a brown powder. Yield: 291 mg (67%); 1H NMR (300MHz, CDCl3) δ (ppm) 6.91 (s, 2H, Ar-H), 6.27 (d, J = 4.0 Hz, 2H, pyrrole-H), 6.10 (d, J = 4.0 Hz, 2H, pyrrole-H), 2.45 (s, 6H, CH3), 2.36 (s, 3H, CH3), 2.12 (s, 6H, CH3); 13C NMR (100MHz, CD2Cl2) δ (ppm) 153.5, 139.6, 137.0, 137.0, 136.8, 133.6, 127.6, 127.5, 117.4, 21.1, 19.8, 16.3; ESI MS (M+H)+: m/z 291.2; HR-ESI MS (M+H)+: m/z calcd for C20H23N2: 291.1861; found: 291.1869. UV/Vis (CHCl3) λmax nm (logε): 450.0 (4.50) and 479.0 (4.46).  CN  NH  N  IV-3 meso-4-cyanophenyl dipyrrin ligand (IV-3). IV-3 was synthesized based on the previously reported procedure,84 starting with 4-formylbenzonitrile (197 mg, 1.5 mmol) and IV-1 (260 mg, 3.21 mmol) to afford a brown powder. Yield: 250 mg (61%); 1H NMR (300MHz, CD2Cl2) δ 170  (ppm) 7.73 (d, J = 8.6 Hz, 2H, Ar-H), 7.56 (d, J = 8.5 Hz, 2H, Ar-H), 6.33 (d, J = 4.0 Hz, 2H, pyrrole-H), 6.18 (d, J = 4.2 Hz, 2H, pyrrole-H), 2.43 (s, 6H, CH3); ESI MS (M+H)+: m/z 274.2; HR-ESI MS (M+H)+: m/z calcd for C18H16N3: 274.1344; found: 274.1349. UV/Vis (CHCl3) λmax nm (A): 483.0 (1.407).  Cl  Cl  NH  N  IV-4 meso-2,6-dichlorophenyl dipyrrin ligand (IV-4). The same procedure was used as in the synthesis of IV-3, starting with 2,6-dichlorobenzaldehyde (262 mg, 1.5 mmol) and IV-1 (260 mg, 3.21 mmol) to afford a brown powder. Yield: 296 mg (62%); 1H NMR (300MHz, CD2Cl2) δ (ppm) 7.43-7.46 (m, 2H, Ar-H), 7.32-7.37 (m, 1H, Ar-H), 6.22 (d, J = 4.1 Hz, 2H, pyrrole-H), 6.15 (d, J = 4.1 Hz, 2H, pyrrole-H), 2.43 (s, 6H, CH3); ESI MS (M+H)+: m/z 317.2; HR-ESI MS (M+H)+: m/z calcd for C17H15N235Cl2: 317.0612; found: 317.0610. UV/Vis (CHCl3) λmax nm (A): 490.0 (1.366).  N H  CHO  IV-5 5-methylpyrrole-2-carbaldehyde (IV-5). According to the previously reported procedure,86 some modifications have been made for synthesis of IV-5. To a mixture of DMF (4.5 mL, 0.057 171  mol) and DCE (19 mL) cooled to -50˚C was slowly added POCl3 (4.2 mL, 0.045 mol). The reaction mixture was warmed to 0˚C and stirred for 30 min, followed by addition of IV-1 (3.36 g, 0.041 mol, dissolved in 14 mL DCE). The mixture was stirred for 1 h at 0˚C before heating to reflux for 30 min. The reaction mixture was allowed to cool to room temperature and NaOAc (18.4 g, 0.225 mol, dissolved in 100 mL water) was slowly added. After refluxing for an additional hour, the mixture was cooled to room temperature. The organic layer was washed with water and brine. After removal of the organic solvent in vacuo, the residue was purified by flash chromatography on silica gel, eluting with 20% EtOAc in hexanes, to give an off-white solid.86 Yield: 3.5 g (78%); 1H NMR (300MHz, CDCl3) δ (ppm) 10.60 (br. s, 1H, NH), 9.35 (s, 1H, CHO), 6.92 (t, J = 3.2 Hz, 1H, pyrrole-H), 6.07 (t, J = 3.0 Hz, 1H, pyrrole-H), 2.39 (s, 3H, CH3); EI MS (M+): m/z 109. HR-EI MS (M+) m/z calcd for C6H7NO 109.0528, found 109.0528.  N  HN  NH  N  2HBr  IV-6 bisdipyrrin ligand (IV-6). The same procedure was used as in the synthesis of III-20, starting from IV-5 (54 mg, 0.5 mmol) to afford a black solid. Yield: 210 mg (79%); ESI MS (M+H)+: m/z 369.3; HR-ESI MS (M+H)+: m/z calcd for C24H25N4: 369.2079; found: 369.2090. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 590.0 (0.777).  172  NC N H  IV-7 3-cyano-2,4-dimethylpyrrole (IV-7). IV-7 was synthesized based on the previously reported procedures,101 starting with  2-(2-cyano-l-methylvinylamino)-N-methoxy-N-methyl-  acetamide87 (0.68 g, 3.72 mmol) to afford a white solid. Yield: 0.17 g (39%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.98 (br. s, 1H, NH), 6.38 (d, J = 1.2 Hz, 1H, pyrrole-H), 2.39 (s, 3H, CH3), 2.15 (s, 3H, CH3), 1.57 (s, 3H, CH3); EI MS (M+): m/z 120.  N  CN  HN  NC  NH  N  2HBr  IV-8 bisdipyrrin ligand (IV-8). The same procedure was used as in the synthesis of II-22, starting from II-16 (100 mg, 0.34 mmol) and IV-7 (82 mg, 0.68 mmol) to give a red solid. Yield: 190 mg (85%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.22 (s, 2H, meso-H), 2.62 (s, 6H, CH3), 2.58 (s, 6H, CH3), 2.36 (s, 12H, CH3); ESI MS (M+H)+: m/z 497.3; UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 527.0 (0.973).  rack complex (IV-9-2). To a solution of IV-2 (26 mg, 0.09 mmol) and II-22 (27 mg, 0.04 mmol) in CHCl3/MeOH (20 mL/10 mL) was added a solution of Zn(OAc)2 ⋅2H2O (33 mg, 0.15 mmol) in MeOH (1 mL), followed by addition of a solution of NaOAc (41 mg, 0.5 mmol) in 173  MeOH (1 mL). After stirring overnight, the solvent was removed by rotary evaporation. The residue was purified by flash chromatography on silica gel, eluting with CH2Cl2, to give the crude complex which was then purified using gel permeation chromatography eluting with toluene. The target ZnII rack complex was obtained as a dark red solid. Yield: 5 mg (10%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.02 (s, 2H, meso-H), 6.92 (s, 4H, Ar-H), 6.42 (d, J = 3.8 Hz, 4H, pyrrole-H), 6.10 (d, J = 4.1 Hz, 4H, pyrrole-H), 2.41 (s, 6H, CH3), 2.38 (q, J = 7.6 Hz, 4H, CH2), 2.37 (s, 6H, CH3), 2.25 (s, 6H, CH3), 2.13 (s, 6H, CH3), 2.11 (s, 6H, CH3), 2.11 (s, 6H, CH3), 2.03 (s, 6H, CH3), 2.02 (s, 12H, CH3), 1.04 (t, J = 7.6 Hz, 6H, CH3); 13C NMR (100MHz, CDCl3) δ (ppm) 161.4, 158.7, 143.4, 142.1, 139.4, 138.5, 137.9, 136.8, 136.8, 136.5, 135.7, 134.2, 132.1, 131.3, 127.5, 127.4, 121.3, 116.9, 79.3, 77.8, 29.7, 21.1, 19.6, 17.9, 16.6, 15.1, 14.8, 14.7, 11.1, 9.9; MALDI-TOF calcd. 1206.5, found 1206.5 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 495.0 (1.011) and 542.0 (0.750).  rack complex (IV-10-2). The same procedure was used as in the synthesis of IV-9-2, starting from IV-2 (26 mg, 0.09 mmol) and IV-8 (26 mg, 0.04 mmol) to give a dark red solid. Yield: 4 mg (8%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.16 (s, 2H, meso-H), 6.92 (d, J = 3.2 Hz, 4H, Ar-H), 6.45 (d, J = 3.8 Hz, 4H, pyrrole-H), 6.12 (d, J = 4.1 Hz, 4H, pyrrole-H), 2.49 (s, 6H, CH3), 2.46 (s, 6H, CH3), 2.37 (s, 6H, CH3), 2.17 (s, 6H, CH3), 2.16 (s, 6H, CH3), 2.11 (s, 6H, CH3), 2.10 (s, 6H, CH3), 2.00 (s, 12H, CH3); MALDI-TOF calcd. 1200.4, found 1200.5 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 494.0 (0.969) and 546.0 (0.664).  174  rack complex (IV-11-2). The same procedure was used as in the synthesis of IV-9-2, starting from IV-3 (25 mg, 0.09 mmol) and IV-8 (26 mg, 0.04 mmol) to give a dark red solid. Yield: 2 mg (5%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.74 (tt, J = 6.4 and 2.0 Hz, 4H, Ar-H), 7.58 (dt, J = 8.3 and 1.4 Hz, 4H, Ar-H), 7.16 (s, 2H, meso-H), 6.43 (d, J = 4.1 Hz, 4H, pyrrole-H), 6.21 (d, J = 4.1 Hz, 4H, pyrrole-H), 2.48 (s, 6H, CH3), 2.46 (s, 6H, CH3), 2.15 (s, 6H, CH3), 2.14 (s, 6H, CH3); MALDI-TOF calcd. 1166.3, found 1166.4 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 496.0 (1.037) and 546.0 (0.827).  rack complex (IV-12-1). The same procedure was used as in the synthesis of IV-9-2, starting from IV-2 (26 mg, 0.09 mmol) and IV-6 (21 mg, 0.04 mmol) to give a dark blue solid. Yield: 2 mg (4%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.11 (s, 2H, meso-H), 7.00 (d, J = 3.5 Hz, 2H, pyrrole-H), 6.92 (s, 2H, Ar-H), 6.86 (s, 2H, Ar-H), 6.40 (d, J = 3.8 Hz, 4H, pyrrole-H), 6.22 (d, J = 3.5 Hz, 2H, pyrrole-H), 6.08 (d, J = 4.1 Hz, 4H, pyrrole-H), 2.58 (s, 6H, CH3), 2.43 (s, 4H, CH2), 2.38 (s, 6H, CH3), 2.11 (s, 6H, CH3), 2.10 (s, 6H, CH3), 2.02 (s, 6H, CH3), 1.93 (s, 6H, CH3); MALDI-TOF calcd. 1072.4, found 1072.5 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 491.0 (1.085) and 628.0 (0.952).  rack complex (IV-13-1). The same procedure was used as in the synthesis of IV-9-2, starting from IV-3 (25 mg, 0.09 mmol) and IV-6 (21 mg, 0.04 mmol) to give a dark blue solid. Yield: 2 mg (4%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.72 (ddd, J = 16.5, 8.8 and 1.5 Hz, 4H, Ar-H), 7.57 (d, J = 8.5 Hz, 4H, Ar-H), 7.12 (s, 2H, meso-H), 7.00 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.40 (d, J = 4.1 Hz, 4H, pyrrole-H), 6.22 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.17 (d, J = 4.1 Hz, 4H, 175  pyrrole-H), 2.59 (s, 6H, CH3), 2.53 (s, 4H, CH2), 2.05 (s, 12H, CH3), 2.01 (s, 6H, CH3); MALDI-TOF calcd. 1038.3, found 1038.3 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 493.0 (1.181) and 627.0 (1.074).  rack complex (IV-14-1). The same procedure was used as in the synthesis of IV-9-2, starting from IV-4 (29 mg, 0.09 mmol) and IV-6 (21 mg, 0.04 mmol) to give a dark blue solid. Yield: 3 mg (7%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.41 (ddd, J = 10.3, 7.9 and 1.2 Hz, 4H, Ar-H), 7.32 (t, J = 8.0 Hz, 2H, Ar-H), 7.11 (s, 2H, meso-H), 6.99 (d, J = 3.5 Hz, 2H, pyrrole-H), 6.38 (d, J = 3.8 Hz, 4H, pyrrole-H), 6.22 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.15 (d, J = 4.1 Hz, 4H, pyrrole-H), 2.59 (s, 6H, CH3), 2.52 (s, 4H, CH2), 2.10 (s, 6H, CH3), 2.04 (s, 12H, CH3); MALDI-TOF calcd. 1124.1, found 1124.3 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 498.0 (1.044) and 629.0 (0.797).  rack complex (IV-15-2). The same procedure was used as in the synthesis of IV-9-2, starting from IV-2 (26 mg, 0.09 mmol) and III-22 (28 mg, 0.04 mmol) to give a dark blue solid. Yield: 2 mg (3%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.41 (s, 2H, meso-H), 7.38 (s, 2H, pyrrole-H), 7.19 (s, 4H, Ar-H), 7.03 (s, 2H, Ar-H), 6.94 (s, 2H, Ar-H), 6.81 (s, 2H, Ar-H), 6.53 (d, J = 1.5 Hz, 2H, pyrrole-H), 6.41 (d, J = 4.1 Hz, 4H, pyrrole-H), 6.09 (d, J = 3.8 Hz, 4H, pyrrole-H), 2.49 (s, 6H, CH3), 2.41-2.43 (m, 16H, CH2 and CH3), 2.38 (s, 6H, CH3), 2.20 (s, 6H, CH3), 2.05 (s, 12H, CH3), 1.88 (s, 6H, CH3); MALDI-TOF calcd. 1252.5, found 1252.6 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 493.0 (1.531) and 637.0 (0.878).  176  ZnII complexes (IV-16). The same procedure was used as in the synthesis of IV-9-2, starting from IV-2 (26 mg, 0.09 mmol) and III-24 (28 mg, 0.04 mmol) to give dark green solids. IV-16-3 (rack): Yield: 9 mg (17%); 1H NMR (300MHz, CDCl3) δ (ppm) 7.18 (s, 2H, meso-H), 6.90 (s, 4H, Ar-H), 6.84 (s, 2H, Ar-H), 6.70 (s, 2H, Ar-H), 6.66 (s, 2H, Ar-H), 6.19 (d, J = 3.9 Hz, 4H, pyrrole-H), 5.96 (d, J = 4.0 Hz, 4H, pyrrole-H), 2.78 (q, J = 7.3 Hz, 4H, CH2), 2.59 (s, 6H, CH3), 2.33 (s, 6H, CH3), 2.11 (s, 4H, CH2), 2.09 (s, 6H, CH3), 2.03 (s, 12H, CH3), 1.98 (s, 12H, CH3), 1.81 (s, 6H, CH3), 1.71 (s, 6H, CH3), 1.28 (t, J = 7.3 Hz, 6H, CH3);  13  C NMR  (75MHz, CDCl3) δ (ppm) 161.9, 158.0, 157.8, 144.5, 142.8, 139.2, 138.0, 137.0, 136.8, 136.7, 136.4, 135.9, 135.7, 135.4, 130.9, 130.3, 129.2, 127.3, 127.1, 126.1, 123.3, 121.8, 121.2, 116.5, 29.7, 24.4, 21.1, 21.1, 19.8, 19.4, 18.6, 16.7, 16.5, 13.0, 10.4; MALDI-TOF calcd. 1340.4, found 1340.5 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 492.0 (5.29) and 667.0 (5.25). IV-16-2 (zigzag rack 2A+2B): Yield: 16 mg (20%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.15 (s, 2H, meso-H), 6.90 (s, 4H, Ar-H), 6.85 (s, 4H, Ar-H), 6.81 (s, 2H, meso-H), 6.64 (s, 8H, Ar-H), 6.20 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.13 (d, J = 4.1 Hz, 2H, pyrrole-H), 5.98 (d, J = 3.8 Hz, 2H, pyrrole-H), 5.86 (d, J = 3.8 Hz, 2H, pyrrole-H), 2.77 (q, J = 7.6 Hz, 4H, CH2), 2.60-2.67 (m, 4H, CH2), 2.54 (s, 6H, CH3), 2.47 (s, 6H, CH3), 2.38 (s, 6H, CH3), 2.09 (s, 6H, CH3), 2.08 (s, 6H, CH3), 2.01-2.03 (m, 8H, CH2), 1.98 (s, 12H, CH3), 1.97 (s, 12H, CH3), 1.94 (s, 6H, CH3), 1.91 (s, 6H, CH3), 1.84 (s, 6H, CH3), 1.76 (s, 6H, CH3), 1.27 (t, J = 7.2 Hz, 6H, CH3), 1.19 (t, J = 7.3 Hz, 6H, CH3);  13  C NMR (100MHz, CDCl3) δ (ppm) 162.7, 160.7, 158.2, 157.6, 157.3, 157.1,  144.0, 143.5, 142.6, 139.3, 138.4, 138.0, 137.9, 137.0, 136.8, 136.8, 136.4, 135.9, 135.8, 135.7, 135.6, 135.4, 130.8, 130.6, 129.7, 129.7, 129.0, 128.5, 127.2, 126.2, 126.1, 123.7, 122.4, 121.4, 121.2, 120.9, 120.7, 116.7, 116.4, 29.7, 24.7, 24.5, 21.1, 21.1, 19.5, 19.4, 18.6, 18.5, 16.7, 16.7, 177  16.4, 16.4, 12.9, 12.8, 10.4, 10.4; MALDI-TOF calcd. 2036.7, found 2036.7 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 496.0 (5.33) and 672.0 (5.48). IV-16-1 (zigzag rack 2A+3B): Yield: 6 mg (5%); MALDI-TOF calcd. 2732.9, found 2732.9 [(M)+]; UV/Vis (CHCl3) λmax nm (logε): 497.0 (5.31), 623.0 (5.46) and 669.0 (5.56).  CoII complex (IV-17). The same procedure was used as in the synthesis of IV-9-2, starting from IV-2 (26 mg, 0.09 mmol), III-24 (28 mg, 0.04 mmol) and Co(OAc)2•4H2O (38 mg, 0.15 mmol) to give dark blue solids. IV-17-3 (rack): Yield: 2 mg (4%); MALDI-TOF calcd. 1326.6, found 1326.6 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 500.0 (1.000), 637.0 (0.641) and 689.0 (0.970). IV-17-2 (zigzag rack 2A+2B): Yield: 3.9 mg (4.8%); MALDI-TOF calcd. 2017.3, found 2017.3 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 504.0 (0.893), 639.0 (1.017) and 702.0 (1.159).  HN  N  N  NH  IV-18 1,4-bis((Z)-(5-methyl-1H-pyrrol-2-yl)(5-methyl-2H-pyrrol-2-ylidene)methyl)benzene (IV-18). IV-18 was synthesized based on a previously reported procedure,82 starting with terephthalaldehyde (1.96 g, 14.6 mmol) and 2-methylpyrrole (5.23g, 64.5 mmol) to afford a dark brown solid. Yield: 1.44 g (23%); 1H NMR (400 MHz, CDCl3) δ (ppm) 7.52 (s, 4H, Ar-H), 6.53 (d, J = 3.8 Hz, 4H, β-dipyrromethene), 6.20 (d, J = 4.1 Hz, 4H, β-dipyrromethene), 2.47 (s, 12H, 178  CH3);  13  C NMR (75 MHz, CD2Cl2) δ (ppm) 154.56, 140.35, 138.25, 138.10, 130.54, 129.26,  118.10, 16.57; Anal. Calcd. for: C28H26N4·H2O: C, 77.04; H, 6.46; N, 12.83. Found: C, 76.62; H, 6.09; N, 12.50. UV/Vis (CHCl3) λmax nm (A): 449.0 (0.972).  HN  N  N  NH  IV-19 1,4-bis((Z)-(1H-pyrrol-2-yl)(2H-pyrrol-2-ylidene)methyl)benzene (IV-19). The same procedure was used as in the synthesis of IV-18, starting with terephthalaldehyde (3.35 g, 25 mmol) and pyrrole (87 ml, 1.25 mol) to afford a dark brown solid. Yield: 1.46 g (16%); 1H NMR (300 MHz, CD2Cl2) δ (ppm) 7.56-7.76 (m, 8H,  α-dipyrromethane and Ar-H), 6.67-6.73 (m, 4H,  β-dipyrromethene), 6.43-6.49 (m, 4H, β-dipyrromethene); LR-ESI MS (M+H)+: m/z calcd for C24H19N4: 363.5; found: 363.2; UV/Vis (CHCl3) λmax nm (A): 478.0 (1.007).  N  O  N  Zn O  O Zn  N  N  O  IV-20 heteroleptic ZnII complex (IV-20). To a solution of Zinc(II) acetylacetonate (1.03 g, 3.9 mmol) in CHCl3 (50 mL) was added dropwise IV-18 (110 mg, 0.26 mmol, dissolved in 30 mL CHCl3). The reaction mixture was stirred for 4 hours and the solvent was removed in vacuo. The crude product was purified by recrystallization from CH2Cl2/Et2O to afford bright red crystals. 179  Yield: 147 mg (75%); 1H NMR (300 MHz, CD2Cl2) δ (ppm) 7.45 (s, 4H, Ar-H), 6.58 (d, J = 3.88 Hz, 4H, β-dipyrromethene), 6.25 (d, J = 4.11 Hz, 4H, β-dipyrromethene), 5.55 (s, 2H, CHacetylacetonate), 2.31 (s, 12H, CH3-dipyrrin), 2.06 (s, 12H, CH3-acetylacetonate); 13C NMR (75 MHz, CD2Cl2) δ (ppm) 194.8, 160.0, 144.7, 139.7, 139.4, 134.3, 129.9, 117.7, 100.5, 28.5, 17.2; MALDI-TOF calcd. 746.5, found 746.3 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 491.0 (1.450).  N  O  N O Cu N O  Cu O  N  IV-21 heteroleptic CuII complex (IV-21). According to the previously reported procedure,88 some modifications have been made for synthesis of IV-21. To a solution of copper(II) acetylacetonate (1.11 g, 4.24 mmol) in CHCl3 (100 mL) was added IV-19 (257 mg, 0.71 mmol, dissolved in 20 mL CHCl3). The reaction mixture was stirred for 2 h at room temperature. The mixture was passed then through a silica gel pad. The organic solution was collected and concentrated under reduced pressure to give IV-21 as a red solid. Yield: 152 mg (31%); MALDI-TOF calcd. 684.1, found 684.4 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 308.0 (0.423), 339.0 (0.526) and 469.0 (1.249).  180  ZnII rigid ladder (IV-22-L). To a solution of III-22 (39 mg, 0.055 mmol) and IV-20 (37 mg, 0.05 mmol) in CHCl3/MeOH (20 mL/10 mL) was added a solution of NaOAc (27 mg, 0.33 mmol) in MeOH (1 mL). After stirring overnight, the solvent was removed by rotary evaporation. The residue was purified by flash chromatography on silica gel eluting with CH2Cl2/hexanes (3/2) to give the crude product which was then purified using gel permeation chromatography eluting with toluene, followed by washing with CH2Cl2 to afford the target ZnII rigid ladder as a dark green solid. Yield: 2 mg (4%); MALDI-TOF calcd. 2180.7, found 2180.8 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 484 (1.252) and 636 (1.178).  CuII rigid ladder (IV-23-L). The same procedure was used as in the synthesis of IV-22-L, starting from III-22 (39 mg, 0.055 mmol) and IV-21 (34 mg, 0.05 mmol) to give a dark green solid. Yield: 5 mg (10%); MALDI-TOF calcd. 2064.6, found 2064.8 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 482.0 (1.232) and 611.0 (1.067).  O  N H  CHO  IV-24 4-acetyl-3,5-dimethylpyrrole-2-carbaldehyde (IV-24). According to the previously reported procedure,71 some modifications have been made for synthesis of IV-24. To DMF (5 mL), cooled in an ice-water bath, was slowly added POCl3 (0.27 mL, 2.8 mmol). The reaction mixture was stirred for 30 min, followed by addition of II-14 (274 mg, 2 mmol, dissolved in 20 181  mL DCE). The mixture was heated to 85˚C and stirred for 3 h. The reaction was allowed to cool to 0˚C, followed by slow addition of K2CO3 (2.76 g, 20 mmol, dissolved in 10 mL water), and then heated to 85˚C for another 2 h. The mixture was cooled to room temperature, and the organic layer was then washed with water and brine. After removal of the organic layer, the residue was purified by flash chromatography on silica gel eluting with 40% EtOAc in hexanes to give IV-24 as a yellow solid. Yield: 100 mg (30%); 1H NMR (400MHz, CDCl3) δ (ppm) 9.67 (s, 1H, CHO), 9.55 (br. s, 1H, NH), 2.58 (s, 6H, CH3), 2.47 (s, 3H, CH3); EI MS (M+): m/z 165. HR-EI MS (M+) m/z calcd for C9H11NO2 165.0790, found 165.0788.  EtO2C  N H  IV-25 ethyl 2,4-dimethylpyrrole-3-carboxylate (IV-25). The same procedure was used as in the synthesis of II-19, starting from 4-(ethoxycarbonyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid (0.84 g, 4 mmol) to afford a brown solid. Yield: 0.62 g (88%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.88 (br. s, 1H, NH), 6.36 (s, 1H, pyrrole-H), 4.28 (q, J = 7.1 Hz, 2H, CH2), 2.50 (s, 3H, CH3), 2.25 (s, 3H, CH3), 1.36 (t, J = 7.2 Hz, 3H, CH3); EI MS (M+): m/z 167. HR-EI MS (M+) m/z calcd for C9H13NO2 167.0946, found 167.0943.  182  O Ph N H  CHO  IV-26 4-benzoyl-3,5-dimethylpyrrole-2-carbaldehyde (IV-26). The same procedure was used as in the synthesis of IV-24, starting from II-19 (0.40 g, 2 mmol) to afford a yellow solid. Yield: 330 mg (73%); 1H NMR (300MHz, CDCl3) δ (ppm) 10.22 (br. s, 1H, NH), 9.63 (s, 1H, CHO), 7.72-7.74 (m, 2H, Ar-H), 7.55-7.60 (m, 1H, Ar-H), 7.45-7.50 (m, 2H, Ar-H), 2.30 (s, 3H, CH3), 2.29 (s, 3H, CH3); EI MS (M+): m/z 227. HR-EI MS (M+) m/z calcd for C14H13NO2 227.0946, found 227.0941.  EtO2C N H  CHO  IV-27 ethyl 5-formyl-2,4-dimethylpyrrole-3-carboxylate (IV-27). The same procedure was used as in the synthesis of IV-24, starting from IV-25 (0.33 g, 2 mmol) to afford a white solid. Yield: 200 mg (52%); 1H NMR (300MHz, CDCl3) δ (ppm) 10.51 (br. s, 1H, NH), 9.60 (s, 1H, CHO), 4.31 (q, J = 7.0 Hz, 2H, CH2), 2.59 (s, 3H, CH3), 2.56 (s, 3H, CH3), 1.37 (t, J = 7.0 Hz, 3H, CH3); EI MS (M+): m/z 195. HR-EI MS (M+) m/z calcd for C10H13NO3 195.0895, found 195.0903.  183  O  N H  CHO  IV-28 4-acetylpyrrole-2-carbaldehyde (IV-28). IV-28 was synthesized based on a previous reported procedure.102 1H NMR (300 MHz, DMSO-d6) δ (ppm) 12.70 (br. s, 1H, NH), 9.57 (s, 1H, CHO), 7.90 (s, 1H, Pyrrole-H), 7.39 (d, J = 1.4 Hz, 1H, Pyrrole-H), 2.39 (s, 3H, CH3); EI MS (M+): m/z 137. HR-EI MS (M+) m/z calcd for C7H7NO2 137.0477, found 137.0478.  O Ph N H  CHO  IV-29 4-benzoyl-1H-pyrrole-2-carbaldehyde (IV-29). IV-29 was synthesized based on a previously reported procedure.93 1H NMR (300 MHz, DMSO-d6) δ (ppm) 12.86 (br. s, 1H, NH), 9.62 (s, 1H, CHO), 7.80-7.82 (m, 2H, Ar-H), 7.75 (s, 1H, Pyrrole-H), 7.61-7.67 (m, 1H, Ar-H), 7.52-7.57 (m, 2H, Ar-H), 7.46 (d, J = 1.3 Hz, 1H, Pyrrole-H); EI MS (M+): m/z 199. HR-EI MS (M+) m/z calcd for C12H9NO2 199.0633, found 199.0636.  184  dibenzyl β-β’ linked bis(pyrrole-2-carboxylate) (IV-30). IV-30 (n = 1 to 5) were synthesized based on previously reported procedures.46  CO2Bn  BnO2C HN  NH  IV-30, n = 1 IV-30, n = 1: 1H NMR (300 MHz, DMSO-d6) δ (ppm) 11.07 (br. s, 2H, NH), 7.31-7.43 (m, 10H, Ar-H), 5.22 (s, 4H, CH2), 3.36 (s, 2H, CH2), 2.08 (s, 6H, CH3), 2.00 (s, 6H, CH3); EI MS (M+): m/z 470.3. HR-EI MS (M+) m/z calcd for C29H30N2O4 470.2206, found 470.2209.  NH  BnO2C  CO2Bn  HN  IV-30, n = 2 IV-30, n = 2: 1H NMR (300 MHz, DMSO-d6) δ (ppm) 11.04 (br. s, 2H, NH), 7.31-7.43 (m, 10H, Ar-H), 5.23 (s, 4H, CH2), 2.35 (s, 4H, CH2), 2.10 (s, 6H, CH3), 1.91 (s, 6H, CH3); EI MS (M+): m/z 484.3. HR-EI MS (M+) m/z calcd for C30H32N2O4 484.2362, found 484.2363.  BnO2C  CO2Bn HN  NH  IV-30, n = 3 IV-30, n = 3: 1H NMR (300 MHz, DMSO-d6) δ (ppm) 11.07 (br. s, 2H, NH), 7.31-7.43 (m, 10H, Ar-H), 5.23 (s, 4H, CH2), 2.28 (t, J = 7.5 Hz, 4H, CH2), 2.13 (s, 6H, CH3), 2.09 (s, 6H, CH3), 185  1.37-1.47 (m, 2H, CH2); EI MS (M+): m/z 498.4. HR-EI MS (M+) m/z calcd for C31H34N2O4 498.2519, found 498.2521.  NH  BnO2C  CO2Bn  HN  IV-30, n = 4 IV-30, n = 4: 1H NMR (300 MHz, DMSO-d6) δ (ppm) 11.07 (br. s, 2H, NH), 7.31-7.43 (m, 10H, Ar-H), 5.23 (s, 4H, CH2), 2.26-2.30 (m, 4H, CH2), 2.15 (s, 6H, CH3), 2.09 (s, 6H, CH3), 1.32-1.37 (m, 4H, CH2); EI MS (M+): m/z 512.1. HR-EI MS (M+) m/z calcd for C32H36N2O4 512.2675, found 512.2678.  CO2Bn BnO2C  NH  N H  IV-30, n = 5 IV-30, n = 5: 1H NMR (300 MHz, DMSO-d6) δ (ppm) 11.07 (br. s, 2H, NH), 7.31-7.43 (m, 10H, Ar-H), 5.23 (s, 4H, CH2), 2.28 (t, J = 7.5 Hz, 4H, CH2), 2.15 (s, 6H, CH3), 2.10 (s, 6H, CH3), 1.22-1.37 (m, 6H, CH2); EI MS (M+): m/z 526.2. HR-EI MS (M+) m/z calcd for C33H38N2O4 526.2832, found 526.2832.  186  O N  NH  HN  O N  2HBr  IV-31 β-β’ linked bisdipyrrin ligand (IV-31). According to the previously reported procedure,46 some modifications have been made for synthesis of IV-31. To a mixture of IV-30 (n = 1) (235 mg, 0.5 mmol) and 10 mol % palladium on activated carbon (50 mg) in a 250 mL round-bottom flask was added THF (75 mL) and MeOH (25 mL). The mixture was stirred overnight under a hydrogen atmosphere at 1 atm. The reaction mixture was then filtered through Celite to remove the catalyst. The filtrate was collected in a 250 mL round-bottom flask, and then IV-24 (165 mg, 1.0 mmol) was added, followed by the addition of 33% hydrogen bromide in acetic acid (1.5 mL). The solution immediately turned from colourless to dark orange. The reaction mixture was stirred for 2 h at room temperature, and then the organic solvent was removed in vacuo to give the crude product. Trituration of the crude product with diethyl ether gave IV-31 as a red solid. Yield: 260 mg (79%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.23 (s, 2H, meso-H), 2.65 (s, 6H, CH3), 2.40 (s, 6H, CH3), 2.38 (s, 2H, CH2), 2.35 (s, 6H, CH3), 2.32 (s, 6H, CH3), 2.14 (s, 6H, CH3); ESI MS (M+H)+: m/z 497.4; HR-ESI MS (M+H)+: m/z calcd for C31H37N4O2: 497.2917; found: 497.2922; UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 486.0 (0.868).  187  NH  O N  N O  HN  2HBr  IV-32  β-β’ linked bisdipyrrin ligand (IV-32). The same procedure was used as in the synthesis of IV-31, starting from IV-30 (n = 2) (242 mg, 0.5 mmol) to afford a red solid. Yield: 300 mg (89%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.20 (s, 2H, meso-H), 2.62 (s, 6H, CH3), 2.50 (s, 4H, CH2), 2.40 (s, 6H, CH3), 2.31 (s, 6H, CH3), 2.22 (s, 6H, CH3), 2.07 (s, 6H, CH3); ESI MS (M+H)+: m/z 511.4; HR-ESI MS (M+H)+: m/z calcd for C32H39N4O2: 511.3073; found: 511.3060. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 492.0 (0.682).  O  HN  NH  N  N  O  2HBr  IV-33 β-β’ linked bisdipyrrin ligand (IV-33). The same procedure was used as in the synthesis of IV-31, starting from IV-30 (n = 3) (249 mg, 0.5 mmol) to afford an orange solid. Yield: 310 mg (90%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.17 (s, 2H, meso-H), 2.66 (s, 6H, CH3), 2.47 (s, 6H, CH3), 2.39 (s, 6H, CH3), 2.31-2.37 (m, 10H, CH2 and CH3), 2.16 (s, 6H, CH3), 1.42-1.49 (m, 2H, CH2); 13C NMR (100MHz, CDCl3/CD3OD = 2/1) δ (ppm) 194.8, 159.9, 153.5, 145.5, 144.5, 130.3, 128.6, 126.3, 124.6, 120.8, 30.8, 29.0, 23.2, 14.9, 12.7, 12.1, 9.8; ESI MS (M+H)+: m/z 525.4; HR-ESI MS (M+H)+: m/z calcd for C33H41N4O2: 525.3230; found: 188  525.3240. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 487.0 (1.340).  O N  HN  NH  N O  2HBr  IV-34 β-β’ linked bisdipyrrin ligand (IV-34). The same procedure was used as in the synthesis of IV-31, starting from IV-30 (n = 4) (256 mg, 0.5 mmol) to afford an orange solid. Yield: 332 mg (95%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.16 (s, 2H, meso-H), 2.63 (s, 6H, CH3), 2.45 (s, 6H, CH3), 2.39 (s, 6H, CH3), 2.31 (s, 10H, CH2 and CH3), 2.15 (s, 6H, CH3), 1.33 (s, 4H, CH2); ESI MS (M+H)+: m/z 539.4; HR-ESI MS (M+H)+: m/z calcd for C34H43N4O2: 539.3386; found: 539.3395. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 483.0 (1.146).  O  HN N NH 2HBr  N  O  IV-35  β-β’ linked bisdipyrrin ligand (IV-35). The same procedure was used as in the synthesis of IV-31, starting from IV-30 (n = 5) (263 mg, 0.5 mmol) to afford an orange solid. Yield: 330 mg (92%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.16 (s, 2H, meso-H), 2.64 (s, 6H, 189  CH3), 2.46 (s, 6H, CH3), 2.39 (s, 6H, CH3), 2.26-2.31 (m, 10H, CH2 and CH3), 2.16 (s, 6H, CH3), 1.28-1.35 (m, 4H, CH2), 1.14-1.20 (m, 2H, CH2); ESI MS (M+H)+: m/z 553.5; HR-ESI MS (M+H)+: m/z calcd for C35H45N4O2: 553.3543; found: 553.3533. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 481.0 (0.956).  O  Ph  HN  N  NH  2HBr  IV-36  N  O  Ph  β-β’ linked bisdipyrrin ligand (IV-36). The same procedure was used as in the synthesis of IV-31, starting from IV-30 (n = 3) (249 mg, 0.5 mmol) and IV-26 (227 mg, 1.0 mmol) to afford a red solid. Yield: 330 mg (81%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 12.75 (br. s, 2H, NH), 12.50 (br. s, 2H, NH), 7.51 (d, J = 7.6 Hz, 4H, Ar-H), 7.42 (t, J = 7.3 Hz, 2H, Ar-H), 7.30 (d, J = 7.6 Hz, 4H, Ar-H), 7.14 (s, 2H, meso-H), 2.48 (s, 6H, CH3), 2.33-2.38 (m, 10H, CH2 and CH3), 2.17 (s, 6H, CH3), 2.10 (s, 6H, CH3), 1.43-1.50 (m, 2H, CH2); 13C NMR (100MHz, CDCl3/CD3OD = 2/1) δ (ppm) 192.4, 159.3, 152.3, 145.2, 143.7, 138.3, 133.0, 130.1, 128.6, 128.4, 128.2, 126.4, 124.9, 120.7, 29.0, 23.2, 13.4, 12.6, 11.1, 9.7; ESI MS (M+H)+: m/z 649.5; HR-ESI MS (M+H)+: m/z calcd for C43H45N4O2: 649.3543; found: 649.3528. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 491.0 (0.489).  190  O  HN  N  NH  N  2HBr  EtO  O  OEt  IV-37  β-β’ linked bisdipyrrin ligand (IV-37). The same procedure was used as in the synthesis of IV-31, starting from IV-30 (n = 3) (249 mg, 0.5 mmol) and IV-27 (195 mg, 1.0 mmol) to afford an orange solid. Yield: 340 mg (91%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.15 (s, 2H, meso-H), 4.13 (q, J = 7.5 Hz, 4H, CH2), 2.63 (s, 6H, CH3), 2.45 (s, 6H, CH3), 2.40 (s, 6H, CH3), 2.34 (t, J = 7.8 Hz, 4H, CH2), 2.16 (s, 6H, CH3), 1.46 (t, J = 7.3 Hz, 2H, CH2), 1.18 (t, J = 7.2 Hz, 6H, CH3); ESI MS (M+H)+: m/z 585.4; HR-ESI MS (M+H)+: m/z calcd for C35H45N4O4: 585.3441; found: 585.3428. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 485.0 (1.255).  O  HN  NH  N  N  O  2HBr  IV-38 β-β’ linked bisdipyrrin ligand (IV-38). The same procedure was used as in the synthesis of IV-31, starting from IV-30 (n = 3) (249 mg, 0.5 mmol) and IV-28 (137 mg, 1.0 mmol) to afford an orange solid. Yield: 266 mg (84%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.79 (s, 4H, pyrrole-H), 7.55 (s, 2H, meso-H), 2.50 (s, 6H, CH3), 2.36 (t, J = 7.5 Hz, 4H, CH2), 2.30 (s, 6H, CH3), 2.16 (s, 6H, CH3), 1.44-1.45 (m, 2H, CH2); 13C NMR (100MHz, CDCl3/CD3OD = 2/1) δ (ppm) 193.6, 166.3, 148.6, 134.7, 132.5, 132.2, 129.9, 127.6, 126.5, 125.1, 28.5, 26.9, 23.2, 13.3, 9.8; ESI MS (M+H)+: m/z 469.3; HR-ESI MS (M+H)+: m/z calcd for C29H33N4O2: 191  469.2604; found: 469.2611. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 468.0 (0.572).  O Ph  HN N  NH  2HBr  IV-39  N  O Ph  β-β’ linked bisdipyrrin ligand (IV-39). The same procedure was used as in the synthesis of IV-31, starting from IV-30 (n = 3) (249 mg, 0.5 mmol) and IV-29 (199 mg, 1.0 mmol) to afford an orange solid. Yield: 358 mg (95%); 1H NMR (400MHz, CDCl3/CD3OD = 2/1) δ (ppm) 7.80 (s, 2H, pyrrole-H), 7.69 (s, 2H, pyrrole-H), 7.63 (d, J = 7.3 Hz, 4H, Ar-H), 7.55 (s, 2H, meso-H), 7.42 (t, J = 7.3 Hz, 2H, Ar-H), 7.32 (d, J = 7.6 Hz, 4H, Ar-H), 2.49 (s, 6H, CH3), 2.40 (t, J = 7.8 Hz, 4H, CH2), 2.20 (s, 6H, CH3), 1.43-1.51 (m, 2H, CH2); ESI MS (M+H)+: m/z 593.4; HR-ESI MS (M+H)+: m/z calcd for C39H37N4O2: 593.2917; found: 593.2906. UV/Vis (CHCl3/CH3OH = 2/1) λmax nm (A): 471.0 (0.813).  ZnII flexible ladder (IV-40-L). To a solution of IV-31 (27 mg, 0.04 mmol) and IV-20 (20 mg, 0.027 mmol) in CHCl3/MeOH (20 mL/10 mL) was added a solution of NaOAc (41 mg, 0.5 mmol) in MeOH (1 mL). After stirring overnight, the solvent was removed by rotary evaporation. The residue was purified by flash chromatography on neutral alumina eluting with CH2Cl2/MeOH to give the crude product which was then purified using gel permeation chromatography eluting with toluene to afford two separate fractions. The target ZnII ladder was obtained as a yellow solid. Yield: 1 mg (4%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.53-7.55 (m, 192  4H, Ar-H), 7.44-7.48 (m, 4H, Ar-H), 7.22 (d, J = 7.5 Hz, 4H, meso-H), 6.79 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.66 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.64 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.56 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.31 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.29 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.22 (d, J = 3.8 Hz, 2H, pyrrole-H), 6.16 (d, J = 4.1 Hz, 2H, pyrrole-H), 5.71 (d, J = 4.1 Hz, 2H, pyrrole-H), 2.60 (s, 12H, CH3), 2.45-2.48 (m, 28H, CH2 and CH3), 2.34 (s, 6H, CH3), 2.31 (s, 6H, CH3), 1.95-2.11 (m, 24H, CH3), 1.52 (s, 12H, CH3); MALDI-TOF calcd. 2076.7, found 2076.6 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 489.0 (0.630). ZnII Dimer (IV-40-D). The ZnII dimer was obtained as a yellow solid. Yield: 1 mg (5%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.10 (s, 4H, meso-H), 2.53 (s, 12H, CH3), 2.43 (s, 12H, CH3), 2.32 (d, J = 9.4 Hz, 4H, CH2), 2.29 (s, 12H, CH3), 2.27 (s, 12H, CH3), 1.43 (s, 12H, CH3); MALDI-TOF calcd. 1116.4, found 1116.5 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 468.0 (0.405) and 519.0 (0.949).  ZnII flexible ladder (IV-41-L). The same procedure was used as in the synthesis of IV-40-L, starting from IV-32 (27 mg, 0.04 mmol) to afford a yellow solid. Yield: 1 mg (4%); MALDI-TOF calcd. 2104.7, found 2104.7 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 490.0 (0.523). ZnII Dimer (IV-41-D). The ZnII dimer was obtained as a yellow solid. Yield: 2 mg (9%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.10 (s, 4H, meso-H), 2.50 (s, 12H, CH3), 2.36-2.38 (m, 20H, CH2 and CH3), 2.31 (s, 12H, CH3), 1.99 (s, 12H, CH3), 1.40 (s, 12H, CH3); MALDI-TOF calcd. 1144.4, found 1144.5 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 465.0 (0.793) and 516.0 (1.460).  193  ZnII flexible ladder (IV-42-L). The same procedure was used as in the synthesis of IV-40-L, starting from IV-33 (27 mg, 0.04 mmol) to afford a yellow solid. Yield: 2 mg (5%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.50-7.57 (m, 8H, Ar-H), 7.17-7.21 (m, 4H, meso-H), 6.68 (t, J = 4.1 Hz, 3H, pyrrole-H), 6.61-6.63 (m, 4H, pyrrole-H), 6.50 (d, J = 3.8 Hz, 1H, pyrrole-H), 6.22-6.25 (m, 3H, pyrrole-H), 6.19-6.21 (m, 4H, pyrrole-H), 5.78 (d, J = 3.8 Hz, 1H, pyrrole-H), 2.56-2.59 (m, 12H, CH3), 2.42-2.47 (m, 18H, CH3), 2.29-2.34 (m, 20H, CH2 and CH3), 2.25 (s, 6H, CH3), 2.14 (s, 6H, CH3), 2.03 (s, 12H, CH3), 1.92-1.98 (s, 12H, CH3), 1.79 (s, 3H, CH3), 1.69 (s, 3H, CH3); MALDI-TOF calcd. 2140.0, found 2139.8 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 492.0 (1.080). ZnII Dimer (IV-42-D). The ZnII dimer was obtained as a yellow solid. Yield: 1 mg (6%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.15 (d, J = 7.3 Hz, 4H, meso-H), 2.55 (d, J = 4.3 Hz, 12H, CH3), 2.42 (s, 12H, CH3), 2.26-2.33 (m, 20H, CH2 and CH3), 2.22 (s, 12H, CH3), 1.79 (s, 6H, CH3), 1.69 (s, 6H, CH3), 1.51 (t, J = 7.0 Hz, 4H, CH2); MALDI-TOF calcd. 1172.5, found 1172.7 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 503.0 (1.275).  ZnII flexible ladder (IV-43-L). The same procedure was used as in the synthesis of IV-40-L, starting from IV-34 (28 mg, 0.04 mmol) to afford a yellow solid. Yield: 2 mg (8%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.47-7.59 (m, 8H, Ar-H), 7.17-7.20 (m, 4H, meso-H), 6.63 (t, J = 3.8 Hz, 8H, pyrrole-H), 6.21 (t, J = 3.8 Hz, 8H, pyrrole-H), 2.58-2.60 (m, 12H, CH3), 2.47 (s, 12H, CH3), 2.41-2.44 (m, 12H, CH3), 2.37-2.38 (m, 12H, CH3), 2.25-2.30 (m, 24H, CH3), 2.17-2.19 (m, 8H, CH2), 2.05 (s, 12H, CH3), 1.39-1.45 (m, 8H, CH2); MALDI-TOF calcd. 194  2168.0, found 2168.2 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 492.0 (1.319). ZnII Dimer (IV-43-D). The ZnII dimer was obtained as a yellow solid. Yield: 4 mg (17%); 1  H NMR (400MHz, CDCl3) δ (ppm) 7.15 (s, 4H, meso-H), 2.55 (s, 12H, CH3), 2.42 (s, 12H,  CH3), 2.30-2.36 (m, 8H, CH2), 2.25 (s, 12H, CH3), 2.15-2.18 (m, 12H, CH3), 1.79-1.86 (m, 12H, CH3), 1.48 (s, 12H, CH3); MALDI-TOF calcd. 1204.2, found 1204.4 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 502.0 (1.326).  ZnII flexible ladder (IV-44-L). The same procedure was used as in the synthesis of IV-40-L, starting from IV-35 (28 mg, 0.04 mmol) to afford a yellow solid. Yield: 1 mg (3%); MALDI-TOF calcd. 2196.1, found 2196.0 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 495.0 (1.167). ZnII Dimer (IV-44-D). The ZnII dimer was obtained as a yellow solid. Yield: 2 mg (8%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.16 (s, 4H, meso-H), 2.55 (d, J = 2.9 Hz, 12H, CH3), 2.42 (s, 12H, CH3), 2.23-2.30 (m, 32H, CH2 and CH3), 1.81 (d, J = 3.8 Hz, 12H, CH3), 1.30-1.35 (m, 8H, CH2), 1.17-1.23 (m, 4H, CH2); MALDI-TOF calcd. 1228.5, found 1228.6 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 496.0 (0.988).  ZnII flexible ladder (IV-45-L). The same procedure was used as in the synthesis of IV-40-L, starting from IV-36 (32 mg, 0.04 mmol) to afford a yellow solid. Yield: 5 mg (16%); MALDI-TOF calcd. 2388.2, found 2388.1 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 495.0 (1.160) and 509.0 (1.181). ZnII Dimer (IV-45-D). The ZnII dimer was obtained as a yellow solid. Yield: 8 mg (27%); 1  H NMR (400MHz, CDCl3) δ (ppm) 7.69 (d, J = 7.9 Hz, 8H, Ar-H), 7.50 (t, J = 7.3 Hz, 4H, 195  Ar-H), 7.42 (t, J = 7.4 Hz, 8H, Ar-H), 7.10 (d, J = 2.0 Hz, 4H, meso-H), 2.31-2.37 (m, 8H, CH2), 2.27 (s, 12H, CH3), 2.21 (d, J = 6.4 Hz, 12H, CH3), 2.01 (d, J = 4.1 Hz, 12H, CH3), 1.86 (s, 6H, CH3), 1.76 (s, 6H, CH3), 1.52-1.55 (m, 4H, CH2); MALDI-TOF calcd. 1424.4, found 1424.4 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 511.0 (1.417).  ZnII flexible ladder (IV-46-L). The same procedure was used as in the synthesis of IV-40-L, starting from IV-37 (32 mg, 0.04 mmol) to afford a yellow solid. Yield: 2 mg (7%); 1H NMR (400MHz, CDCl3) δ (ppm) 7.49-7.56 (m, 8H, Ar-H), 7.15-7.19 (m, 4H, meso-H), 6.68 (t, J = 3.8 Hz, 3H, pyrrole-H), 6.61-6.62 (m, 4H, pyrrole-H), 6.50 (d, J = 3.8 Hz, 1H, pyrrole-H), 6.18-6.24 (m, 7H, pyrrole-H), 5.78 (d, J = 3.8 Hz, 1H, pyrrole-H), 4.23-4.32 (m, 8H, CH2), 2.56-2.58 (m, 12H, CH3), 2.40 (s, 6H, CH3), 2.28-2.32 (m, 20H, CH2 and CH3), 2.23 (s, 6H, CH3), 2.14 (s, 6H, CH3), 2.03 (s, 12H, CH3), 1.92-1.97 (s, 12H, CH3), 1.79 (s, 3H, CH3), 1.68 (s, 3H, CH3), 1.33-1.35 (m, 4H, CH2), 0.89-0.91 (m, 12H, CH3); MALDI-TOF calcd. 2252.8, found 2252.7 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 494.0 (0.728). ZnII Dimer (IV-46-D). The ZnII dimer was obtained as a yellow solid. Yield: 5 mg (17%); 1  H NMR (400MHz, CDCl3) δ (ppm) 7.13 (d, J = 6.8 Hz, 4H, meso-H), 4.25 (q, J = 7.1 Hz, 8H,  CH2), 2.55 (d, J = 3.5 Hz, 12H, CH3), 2.25-2.33 (m, 20H, CH2 and CH3), 2.21 (d, J = 2.9 Hz, 12H, CH3), 1.78 (s, 6H, CH3), 1.67 (s, 6H, CH3), 1.50 (t, J = 6.7 Hz, 4H, CH2), 0.89 (t, J = 6.7 Hz, 12H, CH3); MALDI-TOF calcd. 1292.5, found 1292.7 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 499.0 (1.284).  196  ZnII flexible ladder (IV-47-L). The same procedure was used as in the synthesis of IV-40-L, starting from IV-38 (25 mg, 0.04 mmol) to afford a yellow solid. Yield: 1 mg (2%); MALDI-TOF calcd. 2027.7, found 2027.9 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 486.0 (0.876). ZnII Dimer (IV-47-D). The ZnII dimer was obtained as a yellow solid. Yield: 0.6 mg (2.8%); 1  H NMR (400MHz, CDCl3) δ (ppm) 7.68 (s, 4H, pyrrole-H), 7.34 (s, 4H, pyrrole-H), 7.11 (s,  4H, meso-H), 2.40 (s, 12H, CH3), 2.27-2.31 (m, 8H, CH2), 2.24 (s, 12H, CH3), 1.69 (s, 12H, CH3), 1.49-1.52 (m, 4H, CH2); MALDI-TOF calcd. 1060.3, found 1060.5 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 483.0 (1.164).  ZnII flexible ladder (IV-48-L). The same procedure was used as in the synthesis of IV-40-L, starting from IV-39 (30 mg, 0.04 mmol) to afford a yellow solid. Yield: 2 mg (7%); MALDI-TOF calcd. 2276.0, found 2275.8 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 488.0 (0.913). ZnII Dimer (IV-48-D). The ZnII dimer was obtained as a yellow solid. Yield: 5 mg (20%); 1  H NMR (400MHz, CDCl3) δ (ppm) 7.85 (d, J = 7.0 Hz, 8H, Ar-H), 7.72 (t, J = 7.9 Hz, 4H,  pyrrole-H), 7.49-7.53 (m, 4H, Ar-H), 7.42-7.46 (m, 12H, Ar-H and pyrrole-H), 7.13 (s, 4H, meso-H), 2.23-2.31 (m, 20H, CH2 and CH3), 1.70 (s, 12H, CH3), 1.52 (t, J = 7.0 Hz, 4H, CH2); MALDI-TOF calcd. 1308.4, found 1308.8 [(M)+]; UV/Vis (CHCl3) λmax nm (A): 488.0 (1.195).  197  5.3 Crystal Data Table 5-1 Crystal data and structure refinement for II-7-2. Temperature  -100.0 + 0.1˚C  Empirical Formula  C85H85N8Co2Cl15  Formula Weight  1868.22  Crystal Colour, Habit  red, plate  Crystal Dimensions  0.08 × 0.20 × 0.35 mm  Crystal System  triclinic  Lattice Type  primitive  Lattice Parameters  a = 16.7103(16) Å b = 17.1894(16) Å c = 18.881(3) Å o  α = 101.334(7) β= 101.137(7)  o  γ = 116.285(5) V= 4519(1) Å  o  3  Space Group  P -1 (#2)  Z value  2  Reflections collected  11798  Independent reflections  7582  Goodness of Fit Indicator  1.05  Final R Indices [I>2σ(I)]  R1 = 0.083, wR2 = 0.221  R indices (all data)  R1 = 0.133, wR2 = 0.256  198  Table 5-2 Crystal data and structure refinement for II-13-2. Temperature  -100.0 + 0.1˚C  Empirical Formula  C90H80N10Co2Cl3  Formula Weight  1632.20  Crystal Colour, Habit  red, plate  Crystal Dimensions  0.12 × 0.50 × 0.50 mm  Crystal System  triclinic  Lattice Type  primitive  Lattice Parameters  a = 13.5936(9) Å b = 18.5791(12) Å c = 24.3507(17) Å α= 90.743(3) β= 92.110(2)  o  o  γ = 102.012(3)  o 3  V= 6009.9(7) Å Space Group  P -1 (#2)  Z value  2  Reflections collected  15694  Independent reflections  7524  Goodness of Fit Indicator  0.95  Final R Indices [I>2σ(I)]  R1 = 0.081, wR2 = 0.205  R indices (all data)  R1 = 0.136, wR2 = 0.221  199  Table 5-3 Crystal data and structure refinement for II-25-3. Temperature  -100.0 + 0.1˚C  Empirical Formula  C114H132N12Zn3  Formula Weight  1866.43  Crystal Colour, Habit  red, prism  Crystal Dimensions  0.08 × 0.12 × 0.25 mm  Crystal System  trigonal  Lattice Type  R-centered  Lattice Parameters  a = 19.650(1) Å b = 19.650 Å c = 60.258(4) Å o  α= 90.0  o  β = 90.0  o  γ = 120.0  3  V= 20150(2) Å Space Group  R –3c (#167)  Z value  6  Reflections collected  3960  Independent reflections  2954  Goodness of Fit Indicator  1.06  Final R Indices [I>2σ(I)]  R1 = 0.037, wR2 = 0.091  R indices (all data)  R1 = 0.054, wR2 = 0.095  200  Table 5-4 Crystal data and structure refinement for II-26-3. Temperature  -100.0 + 0.1˚C  Empirical Formula  C112.5H132.5N12Zn3  Formula Weight  1848.92  Crystal Colour, Habit  red, tablet  Crystal Dimensions  0.12 × 0.18 × 0.50 mm  Crystal System  monoclinic  Lattice Type  primitive  Lattice Parameters  a = 15.887(3) Å b = 18.761(3) Å c = 21.673(3) Å o  α = 90.0  β = 92.527(5)  o  o  γ = 90.0  3  V= 6453.6(18) Å Space Group  P 2/c (#13)  Z value  2  Reflections collected  8444  Independent reflections  5325  Goodness of Fit Indicator  1.05  Final R Indices [I>2σ(I)]  R1 = 0.069, wR2 = 0.186  R indices (all data)  R1 = 0.106, wR2 = 0.204  201  Table 5-5 Crystal data and structure refinement for II-35-3. Temperature  -100.0 + 0.1˚C  Empirical Formula  C115H134N12Zn3Cl2  Formula Weight  1951.35  Crystal Colour, Habit  red, tablet  Crystal Dimensions  0.20 × 0.20 × 0.35 mm  Crystal System  monoclinic  Lattice Type  primitive  Lattice Parameters  a = 14.9377(18) Å b = 37.901(5) Å c = 23.225(3) Å o  α = 90.0  β = 92.749(4)  o  o  γ = 90.0  3  V= 13134(3) Å Space Group  P 21/c (#14)  Z value  4  Reflections collected  17934  Independent reflections  9602  Goodness of Fit Indicator  1.08  Final R Indices [I>2σ(I)]  R1 = 0.101, wR2 = 0.286  R indices (all data)  R1 = 0.153, wR2 = 0.319  202  Table 5-6 Crystal data and structure refinement for III-27-4. Temperature  -100.0 + 0.1˚C  Empirical Formula  C90H74N16Zn4Cl6  Formula Weight  1853.83  Crystal Colour, Habit  green, prism  Crystal Dimensions  0.13 × 0.25 × 0.45 mm  Crystal System  monoclinic  Lattice Type  primitive  Lattice Parameters  a = 15.3033(13) Å b = 31.095(3) Å c = 17.7059(15) Å o  α = 90.0  β = 99.366(4)  o  o  γ = 90.0  3  V= 8313.2(12) Å Space Group  P 21/n (#14)  Z value  4  Reflections collected  10815  Independent reflections  6388  Goodness of Fit Indicator  1.07  Final R Indices [I>2σ(I)]  R1 = 0.085, wR2 = 0.193  R indices (all data)  R1 = 0.159, wR2 = 0.253  203  Table 5-7 Crystal data and structure refinement for III-33-4. Temperature  -100.0 + 0.1˚C  Empirical Formula  C206H254N16Zn4  Formula Weight  3215.73  Crystal Colour, Habit  green, prism  Crystal Dimensions  0.40 × 0.44 × 0.55 mm  Crystal System  monoclinic  Lattice Type  primitive  Lattice Parameters  a = 24.936(3) Å b = 12.9012(17) Å c = 28.201(4) Å o  α = 90.0  β = 95.206(6)  o  o  γ = 90.0  V= 9035(2) Å  3  Space Group  P 2/n (#13)  Z value  2  Reflections collected  21591  Independent reflections  12724  Goodness of Fit Indicator  1.07  Final R Indices [I>2σ(I)]  R1 = 0.058, wR2 = 0.158  R indices (all data)  R1 = 0.105, wR2 = 0.180  204  Table 5-8 Crystal data and structure refinement for III-36-6. Temperature  -170.0 + 0.1˚C  Empirical Formula  C243H219N24 F12Cl9Zn6  Formula Weight  4414.69  Crystal Colour, Habit  green, tablet  Crystal Dimensions  0.11 × 0.22 × 0.40 mm  Crystal System  trigonal  Lattice Type  primitive  Lattice Parameters  a = 24.236(2) Å b = 24.236(2) Å c = 11.8480(6) Å o  α = 90.0  o  β = 90.0  o  γ = 120.0  3  V= 6026.8(6) Å Space Group  P -3 (#147)  Z value  1  Reflections collected  7126  Independent reflections  5647  Goodness of Fit Indicator  1.09  Final R Indices [I>2σ(I)]  R1 = 0.062, wR2 = 0.171  R indices (all data)  R1 = 0.081, wR2 = 0.186  205  Table 5-9 Crystal data and structure refinement for IV-16-3. Temperature  -100.0 + 0.1˚C  Empirical Formula  C84H88N8Zn2  Formula Weight  1340.36  Crystal Colour, Habit  green, tablet  Crystal Dimensions  0.16 × 0.38 × 0.60 mm  Crystal System  monoclinic  Lattice Type  C-centered  Lattice Parameters  a = 19.3999(7) Å b = 12.7918(5) Å c = 28.5681(11) Å o  α = 90.0  β = 92.966(2)  o  o  γ = 90.0  V= 9035(2) Å  3  Space Group  C 2/c (#15)  Z value  4  Reflections collected  8511  Independent reflections  6289  Goodness of Fit Indicator  1.06  Final R Indices [I>2σ(I)]  R1 = 0.044, wR2 = 0.102  R indices (all data)  R1 = 0.072, wR2 = 0.115  206  Table 5-10 Crystal data and structure refinement for IV-23-L. Temperature  -100.0 + 0.1˚C  Empirical Formula  C130H112N16Cu4Cl12  Formula Weight  2577.92  Crystal Colour, Habit  black, prism  Crystal Dimensions  0.15 × 0.30 × 0.50 mm  Crystal System  monoclinic  Lattice Type  C-centered  Lattice Parameters  a = 35.898(4) Å b = 15.203(2) Å c = 24.481(3) Å o  α = 90.0  o  β = 100.757(3) o  γ = 90.0  3  V= 13126(3) Å Space Group  C 2/c (#15)  Z value  4  Reflections collected  6922  Independent reflections  2990  Goodness of Fit Indicator  1.06  Final R Indices [I>2σ(I)]  R1 = 0.105, wR2 = 0.291  R indices (all data)  R1 = 0.187, wR2 = 0.350  207  Table 5-11 Crystal data and structure refinement for IV-42-L. Temperature  -100.0 + 0.1˚C  Empirical Formula  C136H146N16O4Zn4Cl24  Formula Weight  3180.97  Crystal Colour, Habit  orange, plate  Crystal Dimensions  0.15 × 0.20 × 0.25 mm  Crystal System  triclinic  Lattice Type  primitive  Lattice Parameters  a = 12.6924(16) Å b = 14.3388(14) Å c = 22.438(3) Å o  α = 105.588(8) β = 96.193(7)  o  γ = 110.661(6)  o 3  V= 3586.2(8) Å Space Group  P -1 (#2)  Z value  1  Reflections collected  9205  Independent reflections  5960  Goodness of Fit Indicator  1.05  Final R Indices [I>2σ(I)]  R1 = 0.074, wR2 = 0.193  R indices (all data)  R1 = 0.116, wR2 = 0.211  208  Chapter Six Conclusions and Future Work  209  6.1 Conclusions  In this study, the spacer linking two dipyrrin units proved to be the key factor for generation of homoleptic metal complexes (circular helicates and grids). Unlike bipyridine ligands, bisdipyrrin ligands with alkylene groups as the spacers always favour double- or triple-helicates upon metalation. Introduction of a diacetylene group or a fused ring system as the spacer to afford a linear rigid ligand successfully overcame the aforementioned obstacle, and led to formation of circular helicates or grids/hexagons, respectively. Grids and hexagons with channels in their solid states have been specially designed and generated. It was found that generation of the channels was driven by several noncovalent interactions such as π-π stacking, CH/π and F-F interactions. Therefore, porous grids and hexagons using bisdipyrrin ligands are poised for future study of their potential application in gas storage and separation,51-54 catalysis55, 56  and drug release.57, 58  Heteroleptic bisdipyrrin metal complexes (racks and ladders) both possess two distinct ligands. The key to their syntheses is to bypass the formation of homoleptic metal complexes. Bulky substituents attached to the α’-position of the terminal pyrrole rings in ring fused ligands proved to prefer zigzag metal complexes to grids, which allows the generation of racks and zigzag racks without unwanted grids. However, the synthesis of ladders using the same strategy appeared unsuccessful. Therefore, another crucial factor for synthesis of ladders emerged, which is the synthesis of an intermediate acting as both the ligand and the metal ion source. Two heteroleptic metal (ZnII or CuII) complex intermediates were synthesized. The CuII complex 210  paired with ring fused ligands which prefer the metal ions with tetrahedral geometry such as ZnII ions afforded the desired ladders and trace amounts of the unwanted grids. However, the ZnII complex teamed with alkylene-linked ligands gave a small amount of the expected ladders and large amounts of homoleptic double-helicates since the ligands lacked a geometry preference for metal ions. In short, it appears that controlled synthesis of heteroleptic racks and ladders is feasible, which opens a path to fabrication of multicomponent supramolecular architectures using bisdipyrrin ligands to imitate complex and diverse biological systems.59-61  6.2 Future Work  Myriad supramolecular systems in nature, ribosomes for example, fulfill diverse and sophisticated biological functions through noncovalent interactions of covalent building blocks.103 Inspired by these biological processes, many artificial supramolecular systems have been designed and generated for various potential applications. Although synthetically attractive due to their high symmetry, homoleptic architectures are not the most important structures for diverse and complex biological systems. The larger the variety of components involved, such as in heteroleptic systems, the more information can be stored in the architectures. Minimizing the production of homoleptic structures during the synthesis of desired heteroleptic structures is the difficulty that has most limited progress in this area. Inspired from the successful synthesis of homoleptic grids and hexagons in chapter 3, an unsymmetric ring fused bisdipyrrin ligand VI-1 can be designed. The self-assembly of this unsymmetric ligand can theoretically afford four grids in the presence of ZnII. However, the 211  introduction of a bulky 3,5-dimethylphenyl group at the α’-position of one terminal pyrrole ring may favour only one isomer VI-2 because of the other three suffering at least one unfavourable steric interaction caused by two these bulky groups at a single coordination centre (Scheme 6-1).104  COOH  HOOC HN  N H  NH  CHO  OHC N  HN  NH  N H HBr  HBr HBr ZnII = N  HN  NH  N  α'  NaOAc  2HBr Desired grid VI-2  VI-1  Other three possible isomers  Scheme 6-1 Synthetic route for preparation of unsymmetric ring fused bisdipyrrin ligand and its corresponding ZnII grid.  212  With the successful controlled synthesis of heteroleptic racks IV-16 in hand, we could explore more complicated systems with more information stored by replacing dipyrrin ligand IV-2 with bisdipyrrin ligand IV-8 (Scheme 6-2). The diacetylene spacer in IV-8 allows the two dipyrrin units to adjust themselves to fulfill their roles in different architectures by rotation. Therefore, two triangles (1A+2B and 2A+1B) and one trapezoid 3A+1B are expected to form since ligand III-24 prefers zigzag complexes to grids. More optimizations on the structure of ligand IV-8, such as introduction of bulky substituents at the α’-position, may surpass the generation of triangle 1A+2B owing to unfavourable steric hindrance to afford an even more controlled reaction.  N N  HN  NH  N  α'  CN  HN  NC  NH  N  α'  2HBr  2HBr  III-24 (A)  IV-8 (B)  NaOAc ZnII =  1A+2B  2A+1B  3A+1B  Scheme 6-2 Synthetic route for preparation of heteroleptic ZnII complexes using bisdipyrrin ligand III-24 and IV-8. 213  References  1.  J. M. Lehn, Supramolecular Chemistry-Concepts and Perspectives, VCH, Weinheim, 1995.  2.  G. M. Whitesides and B. Grzybowski, Science, 2002, 295, 2418-2421.  3.  J. S. Lindsey, New J. Chem., 1991, 15, 153-180.  4.  D. P. Funeriu, J.-M. Lehn, G. Baum and D. Fenske, Chem.--Eur. J., 1997, 3, 99-104.  5.  P. N. W. Baxter, Compr. Supramol. 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