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Synthesis and properties of gold(I) and Ruthenium(II) complexes of beta-substituted oligothiophenes Kuchison, Angela Maria 2011

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 SYNTHESIS AND PROPERTIES OF GOLD(I) AND RUTHENIUM(II) COMPLEXES OF BETA-SUBSTITUTED OLIGOTHIOPHENES   by   Angela Maria Kuchison   BSc Chemistry Simon Fraser University, 2005   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)   February 2011 © Angela Maria Kuchison, 2011.   ii ABSTRACT   Oligothiophenes functionalized in the β-position with ethynyl and aryl phosphine groups (57 – 59) are reported.  Compounds 57 and 59 are used as bridging ligands with Au(I) (80 – 82, 93 – 95), while compounds 57 and 58 are used as tridentate ligands with Ru(II) (104 – 112).  The optical and electronic properties of these compounds were studied with absorption and emission spectroscopy, transient absorption spectroscopy, X-ray crystallography, and electrochemistry.  The lowest energy absorption bands and emission bands were found to be sensitive to the substituent and conjugation.  The lowest energy π-based absorption band in complex 80 was blue-shifted, while complexes 93 – 95 and 104 – 112 caused a bathochromic shift in the comparable band.  Complexes 80, 93 and 94 showed ligand based emission at 295 K, complex 95 at temperatures <185 K, and complexes 104 – 112 were nonemissive.  Complex 109 showed a transient absorption at 475 nm with a liftetime of ~100 ns.  Grinding a solid state sample elicited changes in absorption and emission of powders of 57 and 80.  Grinding powdered 57 caused a temporary emission and absorption band hypsochromically shifted from the unground material, whereas grinding 80 caused a bathochromic shift of the absorption bands and strong emission.  These results were attributed to changes in conformation of the terthiophene backbone.  Crystal structures of 80, 81, 93 – 95, 105, 109 and 110 gave insight into the ligand binding and conjugation along the terthiophene backbone.  Sterically bulky substituents increased the torsion angle between adjacent thienyl units in 57 relative to 59; 80 and 82 relative to 57; and 93 and 94 relative to 59.  Solid state structures of complexes 80, 81, and 93 – 95 showed the ligand bridged two Au(I) centres, while structures of 105, 109 and 110 showed 57 binding as a tridentate ligand.  The cyclic voltammograms of 57 – 59, 93 – 95, and 104 – 112 were obtained. Compounds 59 and 93 – 95 electrochemically polymerize.  Complex 95 and poly-95 have Au(I/II) oxidation waves.  Complexes 104 – 110 and 112 also have metal-based oxidation waves.  The Ru(II/III) oxidation waves of 104 – 110 were used to determine the ligand electrochemical parameter of 57.   iii PREFACE  Material in Chapter 2 and Chapter 3 has been previously published as a communication: Kuchison, A. M., Wolf, M. O., Patrick, B. O. Chem. Commun., 2009, 7387-7389.  I am the primary author and principal investigator under the supervision of Professor Michael Wolf.   Dr. Brian Patrick determined the X-ray crystal structure of 57. Material in Chapter 2 and Chapter 4 has been previously published as a full paper: Kuchison, A. M., Wolf, M. O., Patrick, B. O. Inorg. Chem., 2010, 49, 8802-8812.  I am the primary author and principal investigator under the supervision of Professor Michael Wolf.  Dr. Brian Patrick determined the X-ray crystal structures of 59, 93, 94, and 95. Material in Chapter 5 will be published in the future with the authors: Kuchison, A. M., Wolf, M.O., Patrick, B. O.  I am the primary author and principal investigator under the supervision of Professor Michael Wolf.  Dr. Brian Patrick determined the X-ray crystal structures of 105, 109, and 110.       iv TABLE OF CONTENTS  ABSTRACT.................................................................................................................................. ii PREFACE .................................................................................................................................... iii TABLE OF CONTENTS ........................................................................................................... iv LIST OF TABLES ..................................................................................................................... vii LIST OF FIGURES .................................................................................................................... ix LIST OF SYMBOLS AND ABBREVIATIONS.................................................................. xiii LIST OF CHARTS ................................................................................................................... xix LIST OF EQUATIONS............................................................................................................. xx LIST OF SCHEMES ................................................................................................................ xxi ACKNOWLEDGEMENTS .................................................................................................... xxii DEDICATION......................................................................................................................... xxiv  CHAPTER 1 – INTRODUCTION ............................................................................................ 1 Section 1.1 – Overview........................................................................................................... 1 Section 1.2 – Conjugated Materials........................................................................................ 2 Section 1.3 – Oligo-/Polythiophenes ...................................................................................... 4 Section 1.4 – Hybrid Metal-Polymer/Oligomer Materials ..................................................... 7 Section 1.4.1 – General....................................................................................................... 7 Section 1.4.2 – Metal Pyrrole Systems............................................................................... 8 Section 1.4.3 – Metal-PPE/PPV Systems......................................................................... 10 Section 1.4.4 - Metal-Polyaniline Systems....................................................................... 13 Section 1.4.5 – Metal-Oligo and Polythiophene Systems ................................................ 15 Section 1.5 – Goals and Scope ............................................................................................. 19  CHAPTER 2 – BETA-SUBSTITUTED OLIGOTHIOPHENES ........................................ 20 Section 2.1 – Introduction..................................................................................................... 20 Section 2.2 – Experimental................................................................................................... 23 Section 2.2.1 – General..................................................................................................... 23 Section 2.2.2 – Procedures................................................................................................ 23 Section 2.2.3 – X-Ray Crystallography............................................................................ 26 Section 2.3 – Results and Discussion ................................................................................... 28  v Section 2.3.1 – Synthesis .................................................................................................. 28 Section 2.3.2 – Solid-State Molecular Structures............................................................. 30 Section 2.3.3 – Electronic Absorption Spectra................................................................. 34 Section 2.3.4 – Emission Spectra ..................................................................................... 41 Section 2.3.5 – Electrochemistry ...................................................................................... 45 Section 2.4 – Conclusions .................................................................................................... 49  CHAPTER 3 – GOLD(I) PHOSPHINE COMPLEXES ....................................................... 50 Section 3.1 Introduction........................................................................................................ 50 Section 3.2 – Experimental................................................................................................... 54 Section 3.2.1 – General..................................................................................................... 54 Section 3.2.2 – Procedures................................................................................................ 54 Section 3.2.3 – X-Ray Crystallography............................................................................ 56 Section 3.3 – Results and Discussion ................................................................................... 59 Section 3.3.1 – Synthesis and Design............................................................................... 59 Section 3.3.2 – Solid-State Molecular Structures............................................................. 62 Section 3.3.3 – Electronic Absorption Spectra................................................................. 69 Section 3.3.4 – Emission Properties of (AuCl)2P2T3 ........................................................ 71 Section 3.3.5 – Powder X-Ray Diffraction Study of (AuCl)2P2T3 ................................... 74 Section 3.3.6 – Raman Spectra of (AuCl)2P2T3................................................................ 76 Section 3.4 – Conclusions .................................................................................................... 77  CHAPTER 4 – GOLD(I) ACETYLIDE COMPLEXES ...................................................... 79 Section 4.1- Introduction ...................................................................................................... 79 Section 4.2 – Experimental................................................................................................... 82 Section 4.2.1 – General..................................................................................................... 82 Section 4.2.2 – Procedures................................................................................................ 83 Section 4.2.3 – X-Ray Crystallography............................................................................ 85 Section 4.3 – Results and Discussion ................................................................................... 87 Section 4.3.1 – Synthesis and Design............................................................................... 87 Section 4.3.2 – Solid-State Molecular Structures............................................................. 88 Section 4.3.3 – Electronic Absorption Spectra................................................................. 93 Section 4.3.4 – Emission Spectra ..................................................................................... 97 Section 4.3.5 – Excited State Reactivity with Methyl Viologen .................................... 102  vi Section 4.3.6 – Cyclic Voltammetry and Electropolymerization ................................... 106 Section 4.4 – Conclusions .................................................................................................. 112  CHAPTER 5 – RUTHENIUM(II)-PHOSPHINE-OLIGOTHIOPHENE COMPLEXES..................................................................................................................... 115 Section 5.1 – Introduction................................................................................................... 115 Section 5.2 – Experimental................................................................................................. 120 Section 5.2.1 – General................................................................................................... 120 Section 5.2.2 – Procedures.............................................................................................. 120 Section 5.2.3 – X-Ray Crystallography.......................................................................... 124 Section 5.3 Results and Discussion .................................................................................... 126 Section 5.3.1 – Design and Synthesis............................................................................. 126 Section 5.3.2 – Solid-State Molecular Structures........................................................... 130 Section 5.3.3 – Electronic Absorption Spectra............................................................... 135 Section 5.3.4 – Five Coordinate Ru(II) Species ............................................................. 144 Section 5.3.5 – Electrochemistry .................................................................................... 146 Section 5.4 – Conclusions .................................................................................................. 153  CHAPTER 6 – CONCLUSIONS AND FUTURE WORK ................................................ 154 Section 6.1 – Conclusions .................................................................................................. 154 Section 6.2 – Future Work.................................................................................................. 156  REFERENCES ................................................................................................................158  APPENDIX 1 – CRYSTAL STRUCTURE DATA ............................................................ 172    vii LIST OF TABLES  Table 2-1.  Selected bond lengths (Å) and angles (°) for P2T3 (57). ............................................ 33 Table 2-2.  Selected bond lengths (Å) and angles (°) for A2T3 (59). ........................................... 33 Table 2-3.  Electronic absorption maxima of oligothiophenes. ................................................... 34 Table 2-4.  Emission maxima and quantum yields of oligothiophenes. ...................................... 41 Table 2-5.  Oxidation potentials of relevant oligothiophenes...................................................... 46 Table 3-1.  Selected bond lengths and angles for (AuCl)PT3 (76). .............................................. 64 Table 3-2.  Selected bond lengths and angles for (AuSPh)PT3 (77). ........................................... 65 Table 3-3.  Selected bond lengths and angles for (AuSC6F5)PT3 (78)......................................... 65 Table 3-4.  Selected bond lengths and angles for one of the molecules of (AuCl)2P2T3 (80) in the unit cell. ................................................................................................................................ 67 Table 3-5.  Selected bond lengths and angles of (AuCN)2P2T3 (82)............................................ 68 Table 3-6. Electronic absorption maxima of Au(I)-phosphino-oligothiophene complexes. ....... 69 Table 3-7.  Assignments of Raman bands for (AuCl)2P2T3 (80). ................................................ 77 Table 4-1.  Selected bond lengths and angles of (AuPPh3)2A2T3 (93)......................................... 89 Table 4-2.  Selected bond lengths and angles of [(AuCN)2A2T3][n-Bu4N]2 (94). ....................... 91 Table 4-3.  Selected bond lengths and angles of Au2(dppm)A2T3 (95). ...................................... 92 Table 4-4.  Absorption data for compounds at 298 K in CH2Cl2 solutions and 85 K in MeOH/EtOH......................................................................................................................... 95 Table 4-5.  Emission data for compounds at 298 K in CH2Cl2 and 85 K in MeOH/EtOH. ...... 100 Table 4-6.  Calculated excited state redox potentials of compounds......................................... 102 Table 4-7.  XPS analysis data of electropolymerized films....................................................... 110 Table 5-1.  Selected bond lengths (Å) and angles (º) for one of the two molecules of Ru(P2T3)Cl2(CH3CN)·DMF (105) in the unit cell. ............................................................. 132 Table 5-2.  Selected bond lengths (Å) and angles (º) for one molecule of the molecules of [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109) in the unit cell. ............................................................ 133 Table 5-3.  Selected bond lengths (Å) and angles (º) for [Ru(P2T3)(tpy)][PF6]2·0.63 H2O (110).................................................................................................................................... 134 Table 5-4.  Electronic absorption data for Ru(II)-phosphino-oligothiophene complexes. ........ 135 Table 5-5.  Oxidation potentials of Ru(II) complexes. .............................................................. 150 Table 5-6.  Reduction waves of neutral Ru(P2T3) complexes (108 – 110). ............................... 152 Table A1-1.  Selected crystal structure data for P2T3 (57) and A2T3 (59).................................. 172 Table A1-2.  Selected crystal structure data for AuClPT3 (76), AuSPhPT3 (77) and AuSC6F5PT3 (78)...................................................................................................................................... 173 Table A1-3.  Selected crystal structure data for (AuCl)2P2T3 (80) and (AuCN)2P2T3 (82). ...... 174  viii Table A1-4.  Selected bond lengths and angles for the second molecule of (AuCl)2P2T3·CH2Cl2 (80) in the unit cell.............................................................................................................. 175 Table A1-5.  Selected crystal structure data for (AuPPh3)A2T3 (93), [n-Bu4N][(AuCN)2A2T3] (94) and Au2dppmA2T3 (95). .............................................................................................. 176 Table A1-6.  Selected crystal structure data for Ru(P2T3)Cl2(CH3CN) (105), [Ru(P2T3)(2,2´- bpy)Cl][PF6] (109) and [Ru(P2T3)(tpy)][PF6] (110)........................................................... 177 Table A1-7.  Selected bond lengths and angles for the second molecule of Ru(P2T3)Cl2(CH3CN)·DMF (105) in the unit cell. ............................................................. 178 Table A1-8. Selected bond lengths and angles for the second molecule of [Ru(P2T3)(2,2´-bpy) Cl][PF6] (109) in the unit cell. ............................................................................................ 179      ix LIST OF FIGURES  Figure 1-1.  Schematic energy level diagram for polyacetylene. .................................................. 3 Figure 1-2.  Schematic of the valence π-orbitals of thiophene.  Adapted from Ref.46 .................. 6 Figure 1-3.  Absorbance maxima (in CHCl3) and oxidation potentials of thiophene oligomers. From Ref.44 ............................................................................................................................. 6 Figure 1-4.  Three types of metal-containing polymer systems. ................................................... 7 Figure 2-1.  Solid-state molecular structure of P2T3 (57).  Thermal ellipsoids are drawn at 50% probability, and H atoms are omitted for clarity................................................................... 31 Figure 2-2.  a) Solid-state molecular structure of A2T3 (59).  Thermal ellipsoids are drawn at 50% probability and H atoms are omitted for clarity.  b) Solid-state packing of A2T3 (59) looking down the c-axis........................................................................................................ 32 Figure 2-3.  Absorption spectra of P2T3 (57), P2T5 (58) and A2T3 (59) in CH2Cl2 at 298 K. ...... 36 Figure 2-4.  Absorption spectra of a) A2T3 (59) and b) P2T3 (57) in MeOH/EtOH (1:4) at 85 K and 298 K.............................................................................................................................. 37 Figure 2-5.  a) 300 MHz 1H NMR spectra of aromatic region of P2T5 (58) and b) 121 MHz 31P{1H} NMR spectra of P2T5 (58) at 0, 4, and 23 hours in CDCl3. .................................... 39 Figure 2-6.  Absorption spectra of P2T3 (57) powder and changes with grinding and time. ....... 40 Figure 2-7.  Emission (λex = 360 nm) and excitation (λem = 445 nm) spectra of P2T3 (57) in MeOH/EtOH (1:4) showing the decreasing luminescence intensity with increasing temperature. .......................................................................................................................... 42 Figure 2-8.  Emission spectra of a) P2T3  (57) and b) A2T3 (59) in MeOH/EtOH (1:4) at 85 K and 298 K.............................................................................................................................. 43 Figure 2-9.  Emission of several P2T3 (57) samples. ................................................................... 44 Figure 2-10. Emission of ground P2T3 (57) and (PO)2T3 (61). .................................................... 45 Figure 2-11.  CVs of P2T3 (57) and P2T5 (58) on a Pt disk electrode (scan rate = 100 mV/s). Electrolyte = 0.1 M [n-Bu4N][PF6].  Solvent = CH2Cl2. ...................................................... 47 Figure 2-12.  a) CV of A2T3 (59) showing its electropolymerization on a Pt disk electrode (scan rate = 100 mV/s).  Electrolyte = 0.1 M [n-Bu4N][PF6].  Solvent = CH2Cl2.  b) UV/vis absorption spectra of A2T3 (59) and poly-A2T3 (59)............................................................. 48 Figure 3-1. Simplified molecular orbital diagram of an aurophilic interaction.  (Adapted from Ref.136) .................................................................................................................................. 50 Figure 3-2.  Solid-state molecular structures of a) (AuSC6F5)PT3 (78), b) (AuCl)PT3 (76), c) (AuSPh)PT3 (77).  Thermal ellipsoids drawn at 50% probability and H atoms omitted for clarity. ................................................................................................................................... 63 Figure 3-3.  Thiophene ring labels and corresponding S ring assignments in the X-ray structures. .............................................................................................................................................. 64  x Figure 3-4.  Solid-state molecular structure of one of the two (AuCl)2P2T3 (80) molecules in the unit cell. Hydrogen atoms and occluded CH2Cl2 are omitted for clarity and thermal ellipsoids are drawn at 50% probability. .............................................................................. 66 Figure 3-5.  Solid-state molecular structure of (AuCN)2P2T3 (82). Hydrogen atoms and occluded CH2Cl2 are omitted for clarity and thermal ellipsoids are drawn at 50% probability. ......... 68 Figure 3-6.  Absorption spectra of (AuCl)2P2T3 (80) and P2T3 (57) in CH2Cl2 solution. ........... 70 Figure 3-7.  Solid-state reflectance absorption spectra of microcrystalline (AuCl)2P2T3 (80) before and after grinding. ..................................................................................................... 71 Figure 3-8.  Excitation and emission spectra of (AuCl)2P2T3 (80) and P2T3 (57) in CH2Cl2 solution. ................................................................................................................................ 72 Figure 3-9.  a) Emission spectrum of (AuCl)2P2T3 (80) before and after grinding. b) Emission and excitation spectra of ground (AuCl)2P2T3 (80). ............................................................. 73 Figure 3-10.  PXRD of (AuCl)2P2T3 (80) a) as prepared, b) ground........................................... 75 Figure 3-11.  Raman spectra of crystalline and ground (AuCl)2P2T3 (80). ................................. 76 Figure 4-1.  Solid-state molecular structure of (AuPPh3)2A2T3 (93).  Hydrogens have been omitted for clarity and thermal ellipsoids are drawn at 50% probability. ............................ 89 Figure 4-2.  Solid-state molecular structure of [n-Bu4N]2[(AuCN)2A2T3] (94).  Hydrogens have been omitted for clarity and thermal ellipsoids are drawn at 50% probability..................... 90 Figure 4-3.  Solid-state molecular structure of Au2(dppm)A2T3 (95).  Hydrogens and occluded acetone have been omitted for clarity and thermal ellipsoids are drawn at 50% probability. .............................................................................................................................................. 92 Figure 4-4.  Electronic absorption spectra of (AuPPh3)2A2T3 (93), [n-Bu4N]2[(AuCN)2A2T3] (94), and Au2(dppm)A2T3 (95) at 298 K in CH2Cl2. ............................................................ 94 Figure 4-5.  Electronic absorption spectra of a) (AuPPh3)2A2T3 (93), b) [n-Bu4N]2 [(AuCN)2A2T3] (94) at 298 K and 85 K. .............................................................................. 96 Figure 4-6.  Electronic absorption spectrum of Au2(dppm)A2T3 (95) in EtOH/MeOH (4:1) at 298 K and 85 K..................................................................................................................... 97 Figure 4-7.  Fluorescence emission and excitation spectra of (AuPPh3)2A2T3 (93) and [n-Bu4N]2 [(AuCN)2A2T3] (94).............................................................................................................. 98 Figure 4-8.  Variable temperature emission (λex = 427 nm) and excitation spectra (λem = 496 nm) of Au2(dppm)A2T3 (95)................................................................................................. 99 Figure 4-9.  Schematic Jablonski diagram for Au2(dppm)A2T3. ............................................... 100 Figure 4-10.  Emission and excitation of a) (AuPPh3)2A2T3 (93) and b) [n-Bu4N]2 [(AuCN)2A2T3] (94) at 298K and 85 K in EtOH/MeOH. .................................................. 101 Figure 4-11.  Acetonitrile solutions of A2T3 (59) and MV 2+ irradiated with a) 365 nm light and b) broadband white light. .................................................................................................... 104 Figure 4-12.  Acetonitrile solutions of (AuPPh3)2A2T3 (93) and MV 2+ irradiated with a) 365 nm light and b) broadband white light...................................................................................... 105 Figure 4-13.  Acetonitrile solutions of Au2(dppm)A2T3 (95) and MV 2+ irradiated with 365 nm light. .................................................................................................................................... 106  xi Figure 4-14.  Electropolymerization of (AuPPh3)2A2T3 (93) on an ITO electrode (scan rate = 100 mV/s).  Solvent = CH2Cl2.  Electrolyte = 0.1 M [n-Bu4N][PF6]. ................................ 108 Figure 4-15.  Electropolymerization of [n-Bu4N]2[(AuCN)2A2T3] (94) on a Pt disk electrode (scan rate = 100 mV/s).  Solvent = CH2Cl2.  Electrolyte = 0.1 M [n-Bu4N][PF6]. ............ 109 Figure 4-16.  a) Electropolymerization of Au2(dppm)A2T3 on a Pt disk electrode (scan rate = 100 mV/s) and b) CV of poly-Au2(dppm)A2T3 at a Pt disk electrode in monomer-free solution. Electrolyte = 0.1 M [n-Bu4N][PF6].  Solvent = CH2Cl2. ..................................... 111 Figure 4-17.  Solid-state absorption spectra of electropolymerized poly-(AuPPh3)2A2T3, poly- {[n-Bu4N]2[(AuCN)2A2T3]} and poly-Au2(dppm)A2T3 on ITO substrate. ........................ 112 Figure 5-1.  Schematic of electron flow in a DSSC adapted from Ref.224................................. 115 Figure 5-2.  Solid-state molecular structure of one molecule of Ru(P2T3)Cl2(CH3CN) (105). Occluded DMF and H atoms omitted for clarity.  Thermal ellipsoids drawn at 50% probability........................................................................................................................... 131 Figure 5-3.  Solid-state molecular structure of one molecule of [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109).  H atoms and [PF6] - counterion omitted for clarity and thermal ellipsoids drawn at 50% probability. ................................................................................................................. 131 Figure 5-4.  Solid-state molecular structure of [Ru(P2T3)(tpy)][PF6]2·0.63 H2O (110).  H atoms, occluded solvent and counter ions omitted for clarity........................................................ 134 Figure 5-5.  Solution absorption spectra of a) neutral complexes (104 – 107, 111) in CH2Cl2 and b) cationic complexes (108 – 110, 112) in CH3CN. ........................................................... 138 Figure 5-6.  UV-vis absorption spectra of neutral complexes (104 – 107, 111) in EtOH/MeOH at 295 K and 85 K................................................................................................................... 140 Figure 5-7.  UV-vis absorption spectra of cationic complexes (108 – 110, 112) in EtOH/MeOH at 295 K and 85 K............................................................................................................... 141 Figure 5-8.  a) Transient absorption of [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109) in CH3CN and b) fit of decay of band at 507 nm..................................................................................................... 143 Figure 5-9.  Ru(P2T3)Cl2(DMSO) (104) and Ru(P2T3)Cl2(CH3CN) (105) spectra after being in CH2Cl2 overnight with the new band at 729 nm................................................................. 144 Figure 5-10.  1H NMR spectra showing the appearance of DMSO and disappearance of DMSO- Ru monitored with time in CDCl3. ..................................................................................... 145 Figure 5-11.  The angle (θ) between Ru and a coordinated thiophene ring. ............................. 147 Figure 5-12.  a) CV of Ru(P2T3)Cl2(DMSO) (104) and Ru(P2T5)Cl2(DMSO) (111), and b) CV of Ru(P2T3)Cl2(CH3CN) (105), Ru(P2T3)Cl2(4,4'-bpy) (106) and [Ru(P2T3)Cl2(N-Me-4,4'- bpy)][I] (107) on a Pt disk electrode (scan rate = 100 mV/s).  Electrolyte = 0.1 M [n- Bu4N][PF6].  Solvent = CH2Cl2. ......................................................................................... 148 Figure 5-13.  CVs of [Ru(P2T3)(CH3CN)2Cl][PF6] (108), [Ru(P2T3)(tpy)][PF6]2 (110), and [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109) on a Pt disk electrode (scan rate = 100 mV/s). Electrolyte = 0.1 M [n-Bu4N][PF6].  Solvent = CH3CN..................................................... 149 Figure 5-14.  Graph correlating EP2T3 with Ru-S bond length for Ru(P2T3)Cl2(CH3CN), [Ru(P2T3)(2,2'-bpy)Cl][PF6] and [Ru(P2T3)(tpy)][PF6]2. ................................................... 151  xii Figure A1-1.  Solid-state molecular structure of the second (AuCl)2P2T3·CH2Cl2 (80) molecule in the unit cell.  Hydrogen atoms and occluded CH2Cl2 are omitted for clarity and thermal ellipsoids are drawn at 50% probability. ............................................................................ 175 Figure A1-2.  Solid-state molecular structure of the second Ru(P2T3)Cl2(CH3CN)·DMF (105) molecule in the unit cell.  Hydrogen atoms and occluded CH2Cl2 are omitted for clarity and thermal ellipsoids are drawn at 50% probability. ............................................................... 178 Figure A1-3.  Solid-state molecular structure of the second [Ru(P2T3)(2,2´-bpy)Cl][PF6] (109) molecule in the unit cell.  Hydrogen atoms and PF6 counterion are omitted for clarity and thermal ellipsoids are drawn at 50% probability. ............................................................... 179    xiii LIST OF SYMBOLS AND ABBREVIATIONS  Abbreviation Description A amperes Å Ångstrom AcOH acetic acid ADF-DFT Amsterdam density functional - density functional theory Anal. analysis α-AT2 5-(ethynyl)-2,2´-bithiophene α-A2T 2,5-bis(ethynyl)thiophene α-A2T2 5,5´-bis(trimethylsilylethynyl)-2,2´-bithiophene α-A2T3 5,5´´-bis(ethynyl)-2,2´:5´,2´´-terthiophene A2T3 3,3´´-bis(acetylene)-2,2:5´,2´´-terthiophene a.u. arbitrary units 2,2'-bpy 2,2'-bipyridine 4,4'-bpy 4,4'-bipyridine Br2T5 3,3´´´-dibromo-3,3´´´´-dihexyl- 2,2´:5´,2´´:5´´,2´´:5´´´,2´´´´- pentathiophene Br2T3 3,3´´-dibromo-2,2:5´,2´´-terthiophene n-Bu n-butyl °C degrees Celsius Calcd calculated cm centimetre CT charge transfer CV cyclic voltammogram d doublet D dye δ chemical shift (ppm) δ in-plane bending or deformation of bond ∆  difference ∆ heat ° degrees dd doublet of doublets ∆E energy difference between redox couples (mV)  xiv ∆Eg band gap ∆G0 Gibb’s standard free energy DMF dimethylformamide DMSO dimethylsulfoxide dpb   1,4-bis(diphenylphosphino)butane dppa bis(diphenylphosphino)amine dppm bis(diphenylphosphinomethane) DSSC dye-sensitized solar cell ε molar absorptivity (M-1cm-1) Σ the sum of e- electron E1/2 half wave redox potential (V) E* emission energy EA elemental analysis EDOT 3,4-ethylenedioxythiophene e.g. exempli gratia (for example) EI electron ionization EL ligand electrochemical parameter E(M/M+) first electrochemical oxidation wave potential E(M+/M*) excited state oxidation potential E(MV2+/MV+·) reduction potential of MV2+ Eobs Ru(III/II) oxidation wave potential from EL values Ep peak potential, irreversible wave (V) EP2T3 ligand electrochemical parameter of P2T3 esd estimated standard deviation ESI electrospray ionization Et2O diethylether EtOH ethanol eV electron volts F X-ray scattering factor φ X-ray rotation axis Φem emission quantum yield Fc ferrocene g gram  xv η x hapticity HOMO highest occupied molecular orbital HPNPtBu   HN(CH2CH2P(t-Bu2))2 I intensity of the X-ray reflection I2Br2T3 3,3´´-dibromo-5,5´´-diiodo- 2,2:5´,2´´-terthiophene ITO indium doped tin oxide IR infrared J magnetic coupling constant K Kelvin L ligand Ln multiple ligands λem emission wavelength λex excitation wavelength (nm) λmax wavelength at band maximum (nm) LMCT ligand to metal charge transfer LUMO lowest unoccupied molecular orbital m multiplet (NMR), milli M molarity (mol/L), molecule µ micro µ X-ray linear absorption coefficient µA microamperes MALDI-TOF matrix-assisted laser desorption ionization time of flight MeOH methanol mg milligram MHz Megahertz min minute mL millilter MLCT metal-to-ligand charge transfer mm millimeter mmol millimole mol mole MS mass spectra mV millivolts  xvi MV 2+ Methyl Viologen, or paraquat, or N,N’-dimethyl-4,4’-bipyridine dication MV +· N, N'-dimethyl-4,4'-bipyridium cation mW milliwatts m/z mass-to-charge ratio n number of units (ligands, oligomer, polymer), nano NBS N-bromosuccinimide NEt3 triethylamine NHE normal hydrogen electrode NIS N-iodosuccinimide NLO non linear optic nm nanometer N-Me-4,4'-bpy N-methyl-4,4'-bipyridinium NMR nuclear magnetic resonance ω angle the X-ray source makes with the crystal OFET organic field effect transistor OLED organic light emitting diode ORTEP Oak Ridge Thermal Ellipsoid Plot p pico p para PANI polyaniline PEDOT poly(3,4-ethylenedioxythiophene) P, C phosphine, thienyl carbon coordination Ph phenyl (C6H5) POT poly(o-toluidine) (PO)2T2 3,3´-bis(diphenylphosphoryl)-2,2´-bithiophene (PO)2T3 3,3´´-bis(diphenylphosphoryl)-2,2:5´,2´´-terthiophene (PO)2T5 3,3´´´-bis(diphenylphosphoryl)-3,3´´´´-dihexyl- 2,2´:5´,2´´:5´´,2´´5´´´,2´´´´-pentathiophene PPE poly(p-phenyleneethynylene) PPV poly(p-phenylenevinylene) P, S phosphine, thienyl sulphur coordination PT3 3´-(diphenylphosphino)-2,2´:5´2´´-terthiophene PT5 3, 3´´´´-didodecyl-3´´-diphenylphosphino-2,2´:5, 2´´:5´,  2´´´:5´´´,2´´´´-pentathiophene  xvii α-PT 2-diphenylphosphinothiophene α-PT2 5-diphenylphosphino-2,2´-bithiophene α-PT3 5-diphenylphosphino-2,2´:5´,2´´-terthiophene α-P2T 2,5-bis(diphenylphosphino)thiophene α-P2T2 5,5´´-bis(diphenylphosphino)-2,2´-bithiophene α-P2T3 5,5´´-bis(diphenylphosphino)-2,2´:5´,2´´-terthiophene P2T2 3,3´-bis(diphenylphosphino)-2,2´-bithiophene P2T4 3,3´´´´-dihexyl-3´,3´´-bis(diphenylphosphino)-2,5´:2´,2´´:5´´,2´´´- tetrathiophene P2T3 3,3´´-bis(diphenylphosphino)-2,2:5´,2´´-terthiophene P2T5 3,3´´´-bis(diphenylphosphino)-3,3´´´´-dihexyl- 2,2´:5´,2´´:5´´,2´´5´´´,2´´´´-pentathiophene pydppz  3-(pyrid-2'-yl)dipyrido[3,2-a: 2,3'-c] phenazine PXRD powder X-ray diffraction q quartet R linear regression goodness of fit ρ density (g cm-1) Ref. reference s singlet (NMR), second S Siemens µs microseconds (10-6 s) ns nanoseconds (10-9 s) ps picoseconds (10-12 s) σ standard deviation of the X-ray intensity SCE standard calomel electrode sept septet SFU Simon Fraser University sh shoulder t triplet τ lifetime θ angle of diffraction θ angle T2 2,2´-bithiophene T3 2,2:5´,2´´-terthiophene  xviii T4 2,5´:2´,2´´:5´´,2´´´-tetrathiophene T5 2,2´:5´,2´´:5´´,2´´:5´´´,2´´´´-pentathiophene T6 2,2´:5´,2´´:5´´,2´´:5´´´,2´´´´:5´´´´,2´´´´´-sexithiophene Th thienyl THF tetrahydrofuran tht tetrahydrothiophene TMS trimethylsilyl TMS2-A2T3 3,3´´-bis(trimethylsilylacetylene)-2,2:5´,2´´-terthiophene TOF time of flight tpy 2,2';6',2"-terpyridine tripy  2,6-bis(1H-1,2,3-triazol-4-yl)pyridine UBC University of British Columbia UV ultraviolet V volt, volume ν bond stretching νasym asymmetric bond stretching νsym symmetric bond stretching vis visible W watt w weight XPS X-ray photoelectron spectra XRD X-ray diffraction Z number of molecules in a crystallographic unit cell    xix LIST OF CHARTS  Chart 1-1........................................................................................................................................ 2 Chart 1-2........................................................................................................................................ 4 Chart 1-3.  Ref.55,56 ........................................................................................................................ 9 Chart 1-4. Ref.57,58 ....................................................................................................................... 10 Chart 1-5. Ref. 60-62...................................................................................................................... 10 Chart 1-6.  Ref. 63 ........................................................................................................................ 11 Chart 1-7.  Ref.64 ......................................................................................................................... 12 Chart 1-8.  Ref.65 ......................................................................................................................... 13 Chart 1-9...................................................................................................................................... 13 Chart 1-10. Ref. 73,74 .................................................................................................................... 14 Chart 1-11.  Ref. 75 ...................................................................................................................... 15 Chart 1-12.  Ref.76,77 .................................................................................................................... 16 Chart 1-13.  Ref.78 ....................................................................................................................... 16 Chart 1-14.  Ref. 79,80 ................................................................................................................... 17 Chart 1-15.  Ref.81,82 .................................................................................................................... 18 Chart 1-16.  Ref.83 ....................................................................................................................... 19 Chart 2-1. Ref.88-94....................................................................................................................... 21 Chart 2-2...................................................................................................................................... 22 Chart 2-3...................................................................................................................................... 22 Chart 3-1.  Ref.88,91 ...................................................................................................................... 51 Chart 3-2.  Ref.123,139 ................................................................................................................... 52 Chart 3-3...................................................................................................................................... 53 Chart 4-1. Ref.179,180 .................................................................................................................... 79 Chart 4-2. Ref.92,181...................................................................................................................... 80 Chart 4-3. Ref.186 ......................................................................................................................... 81 Chart 4-4...................................................................................................................................... 82 Chart 5-1.  Ref.222, 223................................................................................................................. 116 Chart 5-2.  Ref.86,94 .................................................................................................................... 117 Chart 5-3.  Ref.173 ...................................................................................................................... 118 Chart 5-4.................................................................................................................................... 119 Chart 5-5.................................................................................................................................... 119  xx LIST OF EQUATIONS  Equation 4-1. Ref.211 ................................................................................................................. 102 Equation 4-2.  Ref.211 ................................................................................................................ 102 Equation 5-1. Ref.249 ................................................................................................................. 146  xxi LIST OF SCHEMES  Scheme 1-1. .................................................................................................................................... 5 Scheme 2-1. .................................................................................................................................. 29 Scheme 2-2. .................................................................................................................................. 30 Scheme 2-3. .................................................................................................................................. 30 Scheme 3-1.  Ref.144 ..................................................................................................................... 52 Scheme 3-2. .................................................................................................................................. 59 Scheme 3-3. .................................................................................................................................. 60 Scheme 3-4. .................................................................................................................................. 61 Scheme 3-5. .................................................................................................................................. 61 Scheme 4-1. Ref.191 ...................................................................................................................... 81 Scheme 4-2. .................................................................................................................................. 88 Scheme 4-3. ................................................................................................................................ 107 Scheme 5-1. ................................................................................................................................ 127 Scheme 5-2. ................................................................................................................................ 128 Scheme 5-3. ................................................................................................................................ 129 Scheme 5-4. ................................................................................................................................ 130 Scheme 5-5. ................................................................................................................................ 146   xxii ACKNOWLEDGEMENTS  First I’d like to thank Michael Wolf for being my supervisor for the past several years. His help and support as well as the goals and space he has given me have undoubtedly made me a better scientist and person. This has been an irreplaceable experience and I’m forever grateful for having the opportunity to work in the Wolf lab. A special thanks to my two readers: Mark MacLachlan and Michael Fryzuk.  Their reading of my thesis has decreased the errors present and helped clarify material. Thanks to the many technicians and support staff at UBC.  Especially, Brian Patrick for solving most of the crystal structures in this thesis and Anita Lam for helping me with powder X-ray diffraction.  Saied Kamal was especially helpful for fluorescence lifetime measurements and none of the fluorescence lifetimes in this thesis would have been possible without him. Also, special thanks to the microanalysis staff for measuring the EAs and mass spectra of my many compounds through the years that helped me learn the science I was doing.  I also owe many thanks to Kadek Okuda who helped with obtaining the Raman spectra of (AuCl)2P2T3 and Michael Blades for allowing me access to the instrument.  Also thanks to Jeffrey Nagle (Bowdoin College) for the ADF-DFT calculations of several of the Ru(II) complexes synthesized in this thesis. The entire Wolf and MacLachlan labs that helped my projects get to this point have my gratitude.  Thank you to Agostino Pietrangelo and Marek Majewski who have been the best fumehood neighbours I could ask for. A huge thanks to those who taught me techniques in the lab.  In particular: Tim Kelly for showing me how to use the fluorimeter, Tracey Stott for showing me how to use the UV/vis spectrometer, Stephanie Moore for showing me how to use the IR and Matt Roberts for showing me how to use the cryostat.  Also thank you to Matt Roberts for measuring the transient absorption spectra of [Ru(P2T3)(2,2´-bpy)Cl][PF6].  Thank you also to Glen Bremner for many helpful electrochemistry discussions.  Many thanks to Kai- Steffen Krannig for exploring the chemistry of P2T3 with Pt(II).  Everyone in the lab has undoubtedly contributed to this degree through helpful thoughts and discussion, an encouraging smile or excellent humour.  It has been an honour to work with so many incredible people. My family and friends have been a source of constant support through these several years.  My parents and grandparents have all always encouraged me in my pursuits. My grandpa may be partially responsible for these last few years since he was the first to suggest that I go to  xxiii grad school in my first year of undergrad. I am also very thankful to my great-grandma.  She was the strongest and bravest person I’ve known and she is a source of inspiration to me.  My two siblings, Marielle and Joshua, have also provided me with encouragement and entertainment through these years that I am grateful for. Last but not least, I’d like to thank Michael Katz.  He solved the crystal structure of (AuCl)2P2T3 in this thesis.  In addition, I’ve had many helpful discussions and a great deal of encouragement from him during my graduate experience.  I owe him my thanks for taking care of me when I was sick for months and always trying to brighten my day through either lending a hand or putting a smile on my face.  He made this thesis more enjoyable to complete.  xxiv DEDICATION  To my parents, Don and Cecelia.    1 CHAPTER 1 INTRODUCTION  Section 1.1 – Overview   Millions of homes and businesses across the planet turned off their lights on March 27, 2010 as they participated in Earth Hour. 1  Since 2007 increasing numbers of participants take part in Earth Hour each year, 1  signifying humanity’s growing awareness of climate change.  This mentality inspires creativity in households, governments, academics and industry.  To help lower each person’s carbon footprint, alternative fuels such as solar, wind and hydrogen are considered replacements to burning fossil fuels.  Devices requiring high power input replaced with lower powered alternatives can also decrease each person’s impact on the earth.  The push for green solutions makes materials chemistry research particularly important.  Compounds with desirable properties can be designed and incorporated into applicable devices.  For example, inorganic, organic and polymer compounds with specific absorption energies and redox potentials can be incorporated into photovoltaic cells 2-10  or low-powered light emitting diodes. 4,5,9-14  Molecular and polymer based photovoltaics will have a significant impact as future commercial solar cells. 15,16   Conjugated materials are particularly amenable to these applications since they conduct electrons and can be synthetically modified to incorporate specific properties and useful functionalities.  For example, polyfluorene and poly(p-phenylenevinylene) (PPV) are used in low-powered organic light-emitting diodes (OLEDs). 14  Oligo- and polythiophene materials have also been incorporated into OLEDs, as well as other devices such as photovoltaic cells and field effect transistors. 17  Combining the properties of oligomers and polymers with metal complexes can also result in materials with desirable properties.  For example, when phosphorescent Ir(III) complexes are tethered to emissive polyfluorene both the complex and polymer emit light in OLEDs. 18  Alternatively, combining Ru(II) polypyridine complexes with thienyl appendages, results in complexes used in photovoltaic cells. 19,20   This thesis focuses on the synthesis and derivatization of oligothiophenes.  The sterics and electronics of oligothiophenes were modified through the chosen substituents and the  2 properties of the compounds were examined.  Metal ions were coordinated to the synthesized oligothiophenes and these complexes’ properties are explored.  Section 1.2 – Conjugated Materials  The valence orbitals of molecules such as pyrrole, thiophene, phenylethyne, vinylbenzene and aniline (Chart 1-1, when n = 1) have delocalized π-electrons.  Increases in the number of repeat units leads to longer chain oligomers (n = 2, 3, etc.) or polymers (n  ∞) of the compounds shown in Chart 1-1.  Long chain lengths have more sp 2 -hybridized C atoms and/or heteroatoms over which the π-system is delocalized than short chain lengths, therefore increasing the chain length increases the number of valence π-orbitals.  When enough π-orbitals overlap, a band structure forms in the conjugated material.  Chart 1-1.   Schematically, the band structure formation of polyacetylene is shown in Figure 1-1. Ethylene has one π-orbital (HOMO) and one π * -orbital (LUMO).  Increasing the repeat unit to a dimer, doubles the number of valence π-orbitals and decreases the HOMO/LUMO energy difference.  Similarly, increasing the conjugation length to the trimer, triples the number of valence orbitals with respect to ethylene and further decreases the HOMO/LUMO gap.  In longer oligomers, the energy difference between the π-valence orbitals decreases, until in a polymer of infinite length with a valence band from the overlapping π-orbitals and a conduction band from the overlapping π * -orbitals, forms.  The conductivity of conjugated polymers varies substantially between different types of repeat units.  For example, the conductivity of polyaniline is 10 -10   3 S/cm, 21  whereas the conductivity of polythiophene is three to four orders of magnitude larger at 10 -6 -10 -7  S/cm. 22  Conformational differences can also cause differences in conductivity in polymers such as in trans-polyacetylene and cis-polyacetylene that have conductivities of 10 -5  S/cm 21  and 10 -8  S/cm 23  respectively.  Twisting along conjugated polymer chains influences the degree of π-orbital overlap resulting in changes in the band gap (∆Eg).  Temperature 24  and pressure 25  can also both influence the conformation along a polymer chain and thus effect ∆Eg.   Figure 1-1.  Schematic energy level diagram for polyacetylene.  Doping significantly increases the conductivity in conjugated materials as first discovered by Nobel laureates Shirakawa, Heeger, and MacDiarmid in doped polyacetylene. 21,23,26,27   Conjugated polymers can be doped chemically with oxidants such as iodine 27  (to produce p-type materials with holes in the valence band) or reductants such as sodium naphthalide 27  (to produce n-type materials with electrons in the conduction band). Alternatively, polymers can be electrochemically doped by applying either positive or negative potentials to either oxidize or reduce the polymers respectively. 27  Transient doping via light irradiation (λ > ∆Eg) also creates mobile holes in the valence band and mobile electrons in the conduction band until irradiation ceases. 27   4  One advantage of conjugated materials is that the structure of chemically well-defined monomers can be synthetically modified prior to polymerization.  This synthetic control allows chemists to tune the properties of the resulting polymer.  For example, long alkyl and alkoxy chains have been tethered to polythiophene and PPV to result in materials with higher solubility. 28,29  Functionalizing the backbone can also influence the band gap of the polymer. PEDOT has a band gap of ~1.5 eV, 30  while in contrast polythiophene has a band gap of ~2 eV. 31  Additionally, useful functionalities can be tethered to the backbone to result in polymers with new properties for applications.  For example, molecular switches, 32  crown ethers 33-35  and fullerenes 36  have all been attached to polythiophene backbones and have potential for applications in sensors or electronics (e.g. OFETs, photovoltaics, or OLEDs).  Interestingly, certain thiophene oligomers also have properties useful for direct application in electronic devices. 37-42  Therefore the study of monomers, oligomers and polymers are important in the study of conjugated materials.  Section 1.3 – Oligo-/Polythiophenes  Oligo- and polythiophenes are well studied for their electronic and optical properties. 43  Thiophenes are relatively stable and have well-developed syntheses that enable functionalities with desirable traits to be incorporated in the α-position (2 and 5 positions) and β- positions (3 and 4 positions) (Chart 1-2). 43  Chart 1-2.   Thiophene rings are coupled through bench top chemical synthesis or electrochemical polymerization techniques.  Metal-catalyzed aromatic coupling techniques such as the Ullman, Kumada, Stille, and Suzuki couplings are typically used to prepare thiophene oligomers and polymers. 44  Alternatively, cyclization reactions can be used to form oligo- and polythiophenes. 44  Electrochemical synthesis involves applying an oxidative potential to a solution of thiophene or thiophene oligomers resulting in polymerization. The mechanism of oxidative  5 electropolymerization (Scheme 1-1) involves oxidation of the monomer to a radical cation with the radical localized on the α-position of thiophene.  This species then combines rapidly with another radical.  Elimination of 2H +  then yields the dimer.  Dimers can then react further with other monomers to form trimers, which then can react to form tetramers, etc. until a polymer forms on the electrode surface.  Electrochemical polymerization is advantageous since the polymer is directly deposited on a substrate.  This polymerization technique can have disadvantages since sometimes monomers used in electropolymerization oxidize at a higher potential than the polymer material and therefore during electropolymerization the polymer can be over-oxidized and degrade.  This problem is referred to as the “polythiophene paradox”. 45   Scheme 1-1.     The π valence molecular orbitals of thiophene are shown in Figure 1-2.  As with polyacetylene, going from thiophene to high oligomers to polymer results in a decrease in the energy gap and leads to band formation.  This is observed from red-shifts in the π-based absorbance bands and reduced oxidation potentials with increased conjugation length from bithiophene (1) to sexithiophene (5) (Figure 1-3), for example.  Additionally since the relative energies of the ring localized filled π-orbitals are comparable to the energy of the lone pair on the S atom, thiophene can coordinate with transition metals through its ring system in an η 2 , η 4  or η 5  fashion or through the lone pair on the S atom. 46,47   Backbonding from transition metals into the π * -orbitals of thiophene is also possible.   6  Figure 1-2.  Schematic of the valence π-orbitals of thiophene.  Adapted from Ref. 46     Figure 1-3.  Absorbance maxima (in CHCl3) and oxidation potentials of thiophene oligomers. From Ref. 44    7 Section 1.4 – Hybrid Metal-Polymer/Oligomer Materials  Section 1.4.1 – General  Functionalizing conjugated materials with metal complexes is an attractive prospect since it can combine the properties of the conducting polymer and the metal complex or result in new enhanced or degraded properties.  Metal complexes are incorporated into conjugated polymers in three basic ways characterized as Type I, Type II, and Type III (Figure 1-4). 48-50    Figure 1-4.  Three types of metal-containing polymer systems.   Type I polymers have the metal complex tethered to the conjugated backbone via a saturated linker, such as an alkyl chain.  This prevents electronic communication between the metal complex and the conjugated material, and allows the properties of each to remain electronically isolated.  Therefore, Type I hybrid materials have both the conductive properties of the conjugated materials and the steric, electronic and chemical properties of the metal complexes.  Type II systems have the metal tethered directly on the conjugated backbone.  The degree of electronic interaction between the metal and the polymer in Type II systems depends on the properties of the metal ion and the polymer.  If the metal orbitals overlap with the π- orbitals of the conjugated material, the metal can have an electron-donating or electron- withdrawing effect on the polymer backbone.  The metal can also cause twisting on the polymer  8 chain.  Finally, Type III materials involve the metal complex directly in the conjugation of the polymer.  This influences the conjugation and can dramatically affect the properties of both the metal complex and the polymer.  To better understand the behaviour of the polymer systems, monomer or oligomer systems are often studied since the synthesis and isolation of shorter conjugated length materials is often more straightforward than of the corresponding polymer.  Several reviews of metal-containing conjugated materials exist that focus on metal complexes with polymers and oligomers of pyrrole, 51   p-phenyleneethynylene, 52  aniline, 53  and thiophene. 48-50,54   The following literature review focuses on recent examples of metals appended to the backbone of oligomers and polymers of pyrrole, p-phenyleneethynylene, p- phenylenevinylene, aniline and thiophene.  Section 1.4.2 – Metal Pyrrole Systems  In many hybrid materials containing pyrrole, the pyrrole is functionalised in the 1, 3 or 4 position with an alkyl chain that has a strong ligand such as a chelating polypyridine or macrocycle at the other end of the carbon chain. 51  Many of these systems are studied for electrocatalysis applications. 51  There are few examples of Type II or Type III systems, although porphyrins in which pyrroles are linked in a macrocycle, are active areas of research.  Haddour et al. prepared 6 (Chart 1-3) 55  and the pendant pyrroles were polymerized electrochemically to result in a Type I Ru(II) material. 55  In the presence of  [Co(NH3)5Cl]Cl2, the poly-6 Ru(II) centres were oxidized to Ru(III) with light irradiation. 55  However in the presence of an anticholera toxin, poly-6 was not photoresponsive due to the toxin inhibiting diffusion of [Co(NH3)5Cl]Cl2 into the polymer. 55  This example shows how the polymer serves as a scaffold for the metal complex to interact with external media to participate in electron transfer or binding to toxins.  Recently, Cheung et al. investigated 7 (Chart 1-3). 56  The solid-state structure showed an interaction between an alkyl hydrogen and a CO on the Re, but the long alkyl chain prevented interactions with the pyrrole substituent, 56  making it another Type I material.  Complex 7 also electrochemically polymerized and films of poly-7 could reduce CO2 to CO with an applied potential of –2.5 V. 56    9 Chart 1-3.  Ref. 55,56     When deprotonated, pyrrole can coordinate via the N to a metal ion, as in 8 – 10 57,58  (Chart 1-4).  The 2 position of the pyrrole can also coordinate metal ions such as Hg(II), Ru(II) and Os(II). 59  These complexes were only structurally investigated and therefore are not discussed further here. In the solid-state, 8 and 9 (Chart 1-4) have two planar chelating keto-pyrrole ligands with comparable bond lengths and angles. 57  Magnetic susceptibility and EPR measurements revealed a low spin Co(II) system.  Coordination of Co(II) had little electronic effect on the ligand-based transitions with respect to the free ligand, but 8 and 9 had additional bands between 300-400 nm and >400 nm attributed to MLCT and d-based transitions respectively. 57   Zn(II) has also been coordinated to pyrrole ligands, but via a pyridyl-pyrrole ligand as in 10 (Chart 1-4). 58  Complex 10 has been known since 1927, but was only recently structurally characterized revealing a distorted tetrahedral geometry around the Zn(II) ion. 58   As with the keto-pyrrole ligand, the pyridyl-pyrrole is planar when coordinated to a metal ion. 58   The high energy transitions in the UV-vis absorption spectrum of 10 are very similar to the free ligand absorption bands and 10 has an additional band at 366 nm. 58    10 also emits at 468 nm and forms micro-octahedra crystals. 58  The electrochemical properties of metal-pyrrole Type II complexes have been sparsely investigated and there is room for further investigation.   10 Chart 1-4. Ref. 57,58     Section 1.4.3 – Metal-PPE/PPV Systems  Several poly(p-phenyleneethynylene) (PPE) and PPV Type II metal containing polymers have been studied in detail.  For example, both Cr and Pt have been tethered to PPE systems through coordination with the π-electrons of the polymer: Cr with the phenylene groups 60  and Pt with the ethynyl groups (Chart 1-5). 61,62   Chart 1-5. Ref. 60-62     Coordination of Cr(0) to PPE studied by Wright, with 11 and 12, resulted in a bathochromic shift of the absorbance band from free PPE. 60   In contrast, Weder et al. reported that coordination of Pt(II) and Pt(0) to alkoxy derivatized PPEs with 13 and 14, respectively, hypsochromically shifted the absorbance bands with respect to the metal-free polymers. 61,62   11 Cr(0), Pt(0) and Pt(II) can crosslink PPE polymers.  Heating 11 to 200°C or irradiation with UV light, causes the release of CO(g) and the Cr(0) forms bonds with available ethynyl groups to crosslink the sample to form 12. 60   Much gentler conditions were required to crosslink the Pt polymers.  The degree of crosslinking depends on the concentration of the polymer, the Pt starting material and the amount of styrene in the solution. 61,62  Weder et al. also found that platination of the conjugated backbone quenches emission 61,62  and cross-linked 14 results in an increase in the charge carrier mobility with respect to the metal-free polymer. 62   Another way that metal ions have been tethered to PPE systems is through coordination with a strongly donating 2,2'-bipyridine (2,2'-bpy) group incorporated in the PPE backbone (Chart 1-6). 63  In particular, coordination of Cu(I), Co(II), Ni(II), Zn(II) and Cd(II) has been examined. 63  Coordination of Cu(I), Co(II) or Ni(II) to 15 quenched emission 63   while a new red- shifted absorption band formed at ~450 nm (the ππ *  of unmetallated 15 is λmax = 423 nm). 63  In contrast, coordination of metal ions to 16 resulted in almost no change in the absorbance bands and residual metal-free polymer emission was evident. 63  However, coordination of Zn(II) and Cd(II) to 15 and 16 red-shifted the polymer emission to ~600 nm (15, λem = 459 nm) and 646 nm (16, λem = 482 nm). 63  As with the Cr and Pt PPE systems, these bpy-PPE polymers were cross- linked by the metal ion. 63  Notably, when Cu(I) was added to 16 in CHCl3, a gel formed at high concentrations. 63   Chart 1-6.  Ref. 63     Similarly, 2,2'-bpy has also been incorporated in the PPV backbone and been used to coordinate first, second, and third row transition metals to result in PPV Type II materials. [Ru(2,2'-bpy)2] 2+  and [Os(2,2'-bpy)2] 2+  have both been tethered to 2,2'-bpy-PPV derivatives  12 (Chart 1-7) to result in materials with high photorefractivity. 64  Coordination of the metal ions causes the π-absorption bands to tail to ~600 nm and ~750 nm for 17 and 18 respectively due to a 1 MLCT transition for 17 and a 3 MLCT transition for 18. 64   Chart 1-7.  Ref. 64      Yu’s group has metallated other 2,2'-bpy derivatized PPVs with the first row transition metals Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) (Chart 1-8). 65  The monomer and polymer properties were investigated. 65  Coordination of all the transition metals to 19 and 20 bathochromically shifted the π-based absorption bands.  Interestingly, unlike metallated-15 and metallated-16 prepared by Weder’s group, metallated-20 polymers were all bathochromically emissive with respect to 20 (metallated-20, λem = ~590 nm; 20, λem~515 nm). 65  Despite the observed emission, the metallopolymers quantum yields were significantly lower than the unmetallated polymer. 65  The monomers electrochemical properties were also investigated and all had a reversible oxidation wave at 0.91 V (vs Fc/Fc + ) due to the ligand, lowered from the unmetallated ligand. 65  In addition, metal-based electrochemistry was observed.  Co(II)-19 showed an irreversible Co(II/III) oxidation wave at 0.754 V and a reversible Co(I/II) reduction wave at –0.158 V. 65  Similarly, Fe(II)-19 had a reversible Fe(II/III) oxidation wave at 0.422 V. 65  These examples show that coordination of metal ions to PPE and PPV affects the observed properties.  13 Chart 1-8.  Ref. 65    Section 1.4.4 - Metal-Polyaniline Systems  As with PPE and PPV, no synthetic modification of the polymer backbone is required for direct coordination of metal ions to polyaniline (PANI).  Metal ions can directly coordinate with the conjugated backbone of PANI through coordination with the N (Chart 1-9).  Chart 1-9.    Hirao’s group has investigated Cu(II)-PANI systems. 66-69  Coordination of CuCl2 to PANI causes a hypsochromic shift in the benzenoid to quinoid charge transfer (CT) band and the CuCl2-PANI oxidizes at 0.46 V (vs SCE), higher than free PANI (oxidizes at 0.29 V). 66  Interestingly, the CuCl2-PANI material was more easily reduced to the leucoemeraldine form when compared to unmetallated PANI. 66  CuCl2-PANI was also an effective catalyst at dehydrogenating cinnamyl alcohol to cinnamaldehyde in the presence of O2, 67,68  similar to an FeCl3-PANI system that is also an effective dehydrogenating catalyst. 67  Colour changes of CuCl2-PANI in the presence of oxygen during catalysis suggest that redox activity of the PANI in the hybrid Type II materials is important for the catalysis. 67  Recently, Hirao’s group found  14 that Cu(OAc)2 is effective at oxidizing poly(2-methoxyaniline-5-sulfonic acid) that changes the polymer structure from extended coil to coil. 69   Pd(OAc)2 coordinated to PANI and its derivatives, poly(o-toluidine) (POT) and poly(o- anisidine), are also effective catalysts. 70  These Pd(II) systems were used in Wacker oxidations. 70  As in the case of CuCl2-PANI, the presence of oxygen was required during catalysis and spectral changes with O2 confirmed that the redox activity of the PANI was again important in the catalytic cycle of Pd(OAc)2-PANI systems. 70  Coordination of Pd(OAc)2 to polyaniline derivatives bathochromically shifts the charge transfer band, 70,71  opposite of Cu(II) coordination. 66  These opposing effects allowed for the synthesis of a heterometallic Pd(II)/Cu(II)-PANI system by monitoring the UV/vis absorption spectra with addition of CuCl2 and Pd(OAc)2. 72   Chiral PANI Type II materials have also been investigated by Hirao 73  and Yamamoto. 74  When 21 is coordinated to Pd(II) that coordinates to POT, it caused helicity along the POT backbone (Chart 1-10). 73  The crystal structure of the model monomer, 22, showed that the chiral metal centre induces twisting along the oligo-aniline. 73  This twisting may extend to a helical structure in the polymer. 73  By contrast, Yamamoto prepared a chiral pyridine-derivatized polymer, 23 (Chart 1-10). 74  Tethering NiCl2 and CuCl2 to 23 resulted in materials with a circular dichroism signal, whereas tethering CoCl2 to 23 greatly reduced the observed signal. 74  The authors attributed this to the NiCl2 and CuCl2 groups causing greater polymer ordering than CoCl2. 74  Similar to Hirao’s CuCl2-PANI, 23-NiCl2 and 23-CuCl2 were blue-shifted from 23. 74  Metallation of 23 also quenched the polymer emission. 74   Chart 1-10. Ref. 73,74     Ru(2,2'-bpy)2-oligoaniline complexes have also been synthesized by Hirao (Chart 1-11). 75  The length of the peripheral oligoaniline attached to the 2,2'-bpy dramatically influences  15 the properties of the metal complex.  The cyclic voltammograms (CVs) of the complexes all have oxidation waves characteristic of oligoanilines and Ru(II/III), and reduction waves consistent with reduction of 2,2'-bpy. 75  The photophysical properties were quite different between the complexes: 24 was emissive, whereas 26 was non-emissive. 75  This was attributed to longer oligomers donating electron density to Ru(II) thereby quenching its emission. 75  However, oxidation of 26 did not induce emission, likely because the Ru(II) donates electron density to the oxidized teraniline. 75   As in the previous metallopolymer systems, coordination of metal ions affects the spectroscopic and electronic properties of PANI systems and their catalytic activity.  Chart 1-11.  Ref. 75     Section 1.4.5 – Metal-Oligo and Polythiophene Systems Several hybrid metal oligo- and polythiophene systems have also been designed in which the metal is tethered to the thienyl backbone.  In the examples that follow, the thiophene is either deprotonated or strong donating groups are used to enable metal ion coordination. Direct coordination of metal ions such as Pt(II) to oligothiophenes has been explored by Bäuerle’s group with 27 and 28 (Chart 1-12). 76,77  In both these complexes, the Pt could be reductively eliminated to result in sexithiophene and macrocycles for 27 and 28 respectively. Interestingly, heating caused the elimination of Pt and macrocycle formation 77  for 28 whereas 27 required the oxidation of the Pt(II) either chemically with an oxidant such as silver triflate or potentiostatically and heating would result in mixtures of products. 76  Complex 27 also showed an increase in the conjugation length of the terthiophene unit as evident by a significant bathochromic shift in the ππ *  absorption band with respect to the terthiophene ligand.  The CV showed a  16 Pt(II/IV) irreversible oxidation wave and two reversible oxidation waves from the oligothiophene. 76   Chart 1-12.  Ref. 76,77    Kim’s group has prepared group 10 oligothiophene complexes with various Pd(II) bithiophene and terthiophene systems. 78  As with the polymer systems discussed earlier, Kim’s group incorporated pyridine groups into the oligothiophenes as tethers for metal ions (Chart 1-13). 78  The pyridine and adjacent thiophene cyclometallate the Pd(II) when two other ligands are coordinated to the Pd(II) as in 29, but bond only through the β-C atom of the thiophene when Pd(II) has three other ligands coordinated as in 30.  In the solid-state with the bithiophene ligand, the Pd(II) ion has a square planar coordination geometry and a centre of inversion is present between the C-C bond connecting the thiophenes independent of the number of other ligands on the Pd(II). 78   Chart 1-13.  Ref. 78     17 Holliday’s group has also studied metal-polypyridine systems where the polypyridines bridge EDOT moieties (Chart 1-14). 79,80  Monomer 31 (n = 1) combined the emission properties of the phenanthroline-EDOT ligand and Eu(III) that emitted at 460 nm and 575-700 nm for the ligand and Eu(III) 5 D0 7 F0-4 respectively. 79  Electropolymerized poly-31, though, exclusively emitted from the Eu(III) upon photoexcitation of the ππ *  band of the polymer, 79  evidence for energy transfer from the polymer to the Eu(III). 79  Complex 32 has a slightly different ligand motif that uses 2,6-bis(pyrazol-1-yl)pyridine rather than phenanthroline, resulting in a tridentate framework to bridge the EDOTs. 80  Monomer 32 (n = 1) has a MLCT band in the absorption spectrum as well as π-based transitions, whereas the electropolymerized poly-32 has broad absorbance bands due to the overlapping MLCT and ππ *  of PEDOT. 80  The monomer was emissive with a lifetime > 5 µs at 77 K attributed to a 3 MLCT state. 80  Poly-32 also has two oxidation waves at 0.76 V (Ru(II/III)) and 1.08 V (PEDOT(0/I)), similar to the monomer. 80   Chart 1-14.  Ref. 79,80    Carbanion ligands are also effective tethers for metal ion coordination to oligothiophenes, as explored with carbenes by Cowley et al. 81  and pincer ligands by Holliday et al. 82  The examples from Cowley’s group, 33 (Chart 1-15), all have the absorbance bands of the polymers bathochromically shifted from the respective monomers (n = 1). 81  Oxidation of the metallated polymers also results in an absorbance band at ~700 nm, likely a result of polaron formation along the polythiophene chain. 81  Interestingly, only when MLn = Ir(CO)2Cl, an additional band at 1092 nm was reported, which indicates bipolaron formation along the polymer backbone. 81  The analogous polymer without a transition metal did not have this behaviour.  Poly-34 (Chart 1-15), from Holliday’s group, was also red-shifted with respect to the monomer (34, n = 1). 82   In  18 this case, oxidizing the polymer backbone hypsochromically shifted the LMCT and decreased the ν(CN) for the isonitrile complexes. 82   The blue-shift was attributed to less electron density able to donate to the Pt(II) and the changes in ν(CN) suggests less σ-donation from CN to Pt(II). 82  Both of these results from Holliday’s group reflect communication between a conjugated backbone and Pt(II).  Chart 1-15.  Ref. 81,82    The effects of changes in electron density in oligothiophenes and polythiophene on Ru(II) has been investigated by Mirkin’s group with Ru(II)-phosphino-oligothienyl complexes (for example 35 and 36, Chart 1-16). 83   The hemilabile ligand allowed for a direct probe of the effect of the ligand oxidation state on that of the Ru(II) centre. 83   For 36 when n = 1, the ν(CO) changed from 1992 cm -1  in the neutral complex to 2011 cm -1  when the terthiophene was oxidized. 83   Similarly, the dimer and polymer of this complex were reported as having changes to ν(CO). 83   However for 35 with n =1, no change in ν(CO) occurred upon oxidation. 83   The solid-state structures for 36 showed a lengthened C-S bond on the thiophene bound to the Ru(II) 83  that further suggested an electronic interaction between the thiophene and Ru(II). 83  These examples show metal-thiophene complexes with electronic communication between the conjugated backbone and the metal ion that affects the observed properties.   19 Chart 1-16.  Ref. 83    Section 1.5 – Goals and Scope   Overall, the primary goal of this thesis is the synthesis and evaluation of the properties of new oligothiophene molecules with acetylene and aryl phosphine substituents, and the study of how the properties were affected with tethered Au(I) and Ru(II) ions to form hybrid Type II materials.  Furthermore, whether the phosphine ligand could be used as a bridge or as a multi- dentate ligand was investigated through the use of metal ions with different coordination spheres: Au(I), which tends to adopt a linear geometry, and Ru(II), which is octahedral.  Chapter 2 discusses the synthesis of bis ethynyl and bis aryl phosphino terthiophenes as well as a bis aryl phosphino pentathiophene.  The effect of the substituent and oligomer length on the structure, absorption, emission and electrochemical properties was evaluated.  In Chapter 3 the effect of two Au(I) ions tethered to the bis aryl phosphine is reported.  The absorption spectra and structure are compared to previous Au(I)-aryl phosphine terthiophene complexes.  Pressure effects on the Au(I)-bis-phosphine complex’s absorption and emission properties are also investigated.  These changes are related to the structure and conjugation of the complex. Chapter 4 discusses how using an ethynyl bridge to tether Au(I) ions affects the electronic and structural interaction in Au(I) terthiophene complexes using their X-ray crystal structures, absorption and emission properties.  Finally, Chapter 5 evaluates the use of the bis-phosphine oligothiophenes as tridentate ligands for Ru(II).  Their synthesis and structure, absorption and electrochemical properties are investigated.  20 CHAPTER 2 BETA-SUBSTITUTED OLIGOTHIOPHENES*  Section 2.1 – Introduction  Chemical modifications on ligands are often used to alter their electron donating ability, sterics, and metal-ligand communication.  The specific donor atom/group in the molecule is particularly important in modulating the ligand-metal interaction.  The ligand may influence a metal complex’s excited state lifetime (e.g. cis-RuL2(SCN)2 (37) has τ = 50 ns and cis- RuL2(CN)2 (38) has τ = 166 ns at 298 K, where L = 4,4'-dicarboxyl-2,2'-bipyridyl), 84  cell toxicity (e.g. cisplatin is a more potent than carboplatin), 85  and absorption and emissive properties (e.g. [Ru(2,2´-bpy)2(PT3-P,S)][PF6]2 (39) and [Ru(2,2´-bpy)2(PT3-P,C)][PF6] (40) lowest energy absorption bands are at 394 nm and 456 nm respectively (PT3 = 3´- (diphenylphosphino)-2,2´:5´2´´-terthiophene (41)). 86   This makes ligand synthesis and design an important component of inorganic and materials chemistry. Thiophene has relatively low nucleophilicity 87  and therefore often requires strong donating groups tethered to it for metal ion coordination. Two functionalities that are suitably strongly donating are aryl-phosphine and acetylene moieties.  These groups can be appended to identical halogenated oligothiophene precursors, but have quite different steric and electronic effects when bound to a metal, potentially resulting in different properties.  Acetylide groups are much less sterically demanding than aryl phosphines.  In addition, acetylides may extend the conjugation of the aromatic moiety to which they are directly bound, whereas phosphines have a predominantly steric effect on the conjugation in oligothiophenes. 88  For these reasons, acetylene and aryl phosphine derivatized oligothiophenes were chosen for study as ligands in this thesis. Our group and others have studied phosphine and acetylene substituted oligothiophenes. Chart 2-1 shows several examples of acetylene and phosphine molecules substituted in the α  *  Part of this chapter has been published.  Reproduced in part from Kuchison, A. M., Wolf, M. O., Patrick, B. O. (2009) Conjugated ligand based tribochromic luminescence. Chem. Commun., 7387-7389 (http://dx.doi.org/10.1039/b915089g) – reproduced with permission from The Royal Society of Chemistry. Reproduced in part with permission from Kuchison, A. M., Wolf, M. O., Patrick, B. O. (2010) Photophysical Properties and Electropolymerization of Gold Complexes of 3,3''-diethynyl-2,2':5',2''-terthiophene. Inorg. Chem., 49, 8802-8812 – Copyright 2010 American Chemical Society.  21 positions (42-45, 89  46, 90  48-53 91 ) and β positions (47, 92  54-55, 88  41 and 56 93,94 ) of oligothiophenes.  These compounds have been used to coordinate a variety of metal ions, including Ru(II), Au(I), Pd(II), and Pt(II).  Chart 2-1. Ref. 88-94    Phosphine donors are among the most studied ligands in inorganic chemistry.  The orbitals of the P atom in phosphine ligands allow for σ-donating 95,96  and π-accepting 96,97  properties resulting in strong metal-phosphine interactions with a variety of metal ions.  In addition, phosphino-oligothiophenes coordinated to metal ions can yield electropolymerizable monomers 93  that  allows incorporation of metal centres into functional metallopolymers. Acetylides have also been studied as ligands in a variety of metal complexes.  Acetylides also bond to metal ions as σ-donors and π-acceptors when the metal is coordinated to the terminal C. 98  Additionally, acetylenes can donate electrons from their π-orbitals in an η 2  fashion. 99   The acetylide bond allows for electronic communication between groups across the alkyne.  For example, AuPPh3 coordinated to 45 electronically interacts with the oligothiophene causing a red-shift in the visible absorption bands. 89  In addition, certain metal-acetylide compounds exhibit exceptional emissive 100  and NLO properties. 101  From a materials standpoint,  22 these properties make metal acetylide complexes potentially useful in OLEDs and telecommunications. To expand upon previous work with β-substituted oligothiophenes in the Wolf group, the bis-phosphines, P2T3 and P2T5, and bis-acetylene, A2T3, molecules in Chart 2-2 were designed. Diaryl phosphines were used rather than alkyl phosphines because of the increased air stability found when aryl substituents are used instead of alkyl substituents. 102   Additionally, the three molecules all have free α-positions that allow electropolymerization.  A2T3 can coordinate to 2 metal centres and potentially facilitate intramolecular metal-metal interactions.   P2T3 and P2T5 can also bond to two metal centres or bond in a tridentate manner with one square planar or octahedral metal ion (Chart 2-3).  Chart 2-2.     Chart 2-3.     23 Section 2.2 – Experimental  Section 2.2.1 – General T3, 103  Br2T3 (60) 104  and 2-(3-hexyl-2-thienyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 105  were prepared by a modified literature procedures.  PPh2Cl was purchased from Strem; 2- bromothiophene, 3-hexylthiophene, N-bromosuccinimide (NBS) and N-iodosuccinimide (NIS) from Sigma Aldrich; trimethylsilyl-acetylene from Acros; and n-Bu4NF from Fluka chemicals. Diethyl ether (Et2O) and tetrahydrofuran (THF) were dried over Na/benzophenone. CH2Cl2 was dried over an activated alumina column.  All other solvents were used as received. 1 H, 31 P and 13 C{ 1 H} NMR spectra were obtained on a Bruker AV-300 or a Bruker AV- 400 spectrometer. 1 H and 13 C{ 1 H} NMR spectra were referenced to residual solvent and 31 P{ 1 H} NMR spectra were referenced to external 85% H3PO4.  Electronic absorption spectra were recorded on a Varian-Cary 5000 UV-vis-near-IR spectrophotometer and emission spectra were recorded on a Photon Technology International QuantaMaster fluorimeter.  Infrared spectra were obtained on a Nicolet 6700 FTIR equipped with a Smart Orbit TM  accessory.  Low temperature absorption and emission spectra were obtained using an Oxford OptistatDN cryostat with solutions in 4EtOH:1MeOH containing minimal DMF (to dissolve P2T3 and A2T3).  Cyclic voltammetry was carried out on an Autolab potentiostat with either a platinum disk or ITO working electrode, silver wire reference electrode, and platinum mesh counter electrode. Decamethylferrocene was used to correct the potentials to saturated calomel electrode (SCE). The electrolyte was [n-Bu4N][PF6], which was recrystallized three times from ethanol and heated to 90°C under vacuum for three days prior to use.  Section 2.2.2 – Procedures 3,3´´-Bis(diphenylphosphino)-2,2:5´,2´´-terthiophene (P2T3, 57). An ether solution (50 mL) of Br2T3 (1.00g, 2,46 mmol) was cooled to –78 °C and n-BuLi in hexanes (3.84 mL, 6.15 mmol) was added dropwise.  The reaction was slowly warmed to –30 °C and PPh2Cl (1.15 mL, 6.40 mmol) was added.  The reaction was allowed to warm to room temperature and stirred overnight.  The reaction was quenched by addition of water (50 mL). P2T3 immediately precipitated as a bright yellow solid.  P2T3 was vacuum filtered and collected.  24 Yield: 1.01 g, 67%.  Alternatively, in cases were water did not precipitate the product, the ether was removed in vacuo and the residue rinsed several times with water.  Sonication of the residue with methanol dissolved impurities and resulted in precipitation of P2T3. Crystals suitable for X- ray diffraction were grown from a CDCl3/acetone/hexanes solution. 1 H NMR (300 MHz, CDCl3): δ 6.59 (d, 2H, J = 5 Hz), 7.06 (s, 2H), 7.16 (d, 2H, J = 5 Hz), 7.33 (m, 20H). 31 P{ 1 H} (121 MHz, CDCl3): δ -24.5 (s).  EI-MS m/z 616 (100%, [M] + ).  Anal. Calcd for C36H26P2S3: C, 70.11; H, 4.25.  Found: C, 69.58; H, 4.30.  To prepare ground 57, a powder of 57 was deposited on the surface of a quartz or glass slide.  Pressure was applied to this powder through either scratching it gently with a metal spatula (approximately equal in force to scratching filter paper when obtaining a solid precipitate product) or another quartz slide was put on the other side of the powder to sandwich 57 and one quartz slide was twisted 180°.  3,3´´-Bis(diphenylphosphoryl)-2,2:5´,2´´-terthiophene ((PO)2T3, 61). P2T3 (100 mg, 0.16 mmol) was dissolved in CH2Cl2/acetone (5:1, 6 mL), and 30% H2O2 (~0.03 mL) solution was added via syringe.   The solution was stirred for 2 hours during which time it became darker orange.  The solution was evaporated in vacuo and the residue was dissolved in methanol (10 mL) to which H2O (10 mL) was added.  Immediately, a bright yellow solid precipitated, which was subsequently vacuum filtered.  Yield: 20 mg, 19%. 1 H NMR (300 MHz, CDCl3): δ 7.63 (m. 7H), 7.46 (m, 4H), 7.39 (m, 9H), 7.22 and 7.21 (d, 2H, J = 5 Hz), 7.05 (s, 2H), 6.75 (t, J = 5 Hz). 31 P{ 1 H} NMR (121 MHz, CDCl3): δ 22.2.  EI MS m/z 648 ([M] + ). Anal. Calcd for C36H26O2P2S3·3H2O: C, 61.52; H, 4.59; N, 0.00.  Found: C, 61.98; H, 4.07; N, 0.17.  3,3´´-Dibromo-5,5´´-diiodo- 2,2:5´,2´´-terthiophene (I2Br2T3, 62). Br2T3 (1.00 g, 2.46 mmol) was dissolved in a mixture of AcOH (42 mL) and CHCl3 (83 mL) in the dark.  NIS (1.11 g, 4.92 mmol) was added and the mixture stirred overnight.  The CHCl3 was removed in vacuo, and a yellow solid precipitated.  The precipitate was vacuum filtered, and rinsed 3 times with water, 3 times with MeOH, and once with Et2O to obtain I2Br2T3.  Yield: 1.02 g, 63%. 1 H NMR (300 MHz, CDCl3); δ 7.30 (s, 2H), 7.17 (s, 2H). 13 C{ 1 H} NMR (100 MHz, CDCl3): δ 140, 137, 134, 127, 108, 72.  EI-MS m/z 658 (100%, [M] + ). Anal. Calcd for C12H4Br2I2S3: C, 21.90; H, 0.61. Found: C, 22.07; H, 1.02.  25  3,3´´´-Dibromo-3,3´´´´-dihexyl- 2,2´:5´,2´´:5´´,2´´5´´´,2´´´´-pentathiophene (Br2T5, 63). I2Br2T3 (700 mg, 1.06 mmol), 2-(3-hexyl-2-thienyl)-4,4,5,5-tetramethyl-1,3,2- dioxaborolane (680 mg, 2.30 mmol) and Pd(PPh3)4 (133 mg, 0.11 mmol) were dissolved in N2(g) sparged THF (100 mL).  NaHCO3 solution (18 mL, 0.4 M) was added to the THF solution.  The mixture was heated to reflux and stirred overnight.  The THF was removed in vacuo and the remaining water was extracted with CH2Cl2.  The CH2Cl2 was dried with MgSO4, filtered and the CH2Cl2 was removed in vacuo.  The residue was purified via column chromatography on silica using hexanes as the eluent.  Br2T5 was collected as an orange oil.  Yield: 681 mg, 87%. 1 H NMR (400 MHz, CDCl3);  δ 7.42 (s, 2H), 7.23 (d, 2H, J = 5.2Hz), 7.04 (s, 2H), 6.96 (d, 2H, J = 5.2Hz), 2.78 (t, 4H, J = 7.8Hz), 1.67 (m, 4H), 1.34 (m, 15H), 0.92 (m, 9H). 13 C{ 1 H} NMR (100 MHz, CDCl3): δ 141,135.3, 135.6, 131, 130.1, 129.8, 129, 126, 125, 108, 32, 31, 30, 29, 23, 14.  EI-MS m/z 738 (60%, [M] + ), 572 (100%, [M – C6H13 – Br – 2H] + ). Anal. Calcd for C32H34Br2S5: C, 52.03; H, 4.64; N, 0.00. Found: C, 52.36; H, 4.76; N, 0.19.  3,3´´´-Bis(diphenylphosphino)-3,3´´´´-dihexyl- 2,2´:5´,2´´:5´´,2´´5´´´,2´´´´-pentathiophene (P2T5, 58). Br2T5 (812 mg, 1.11 mmol) was dissolved in diethyl ether (50 mL) and cooled to –78 o C. n-BuLi in hexanes (1.74 mL, 2.78 mmol) was added to the bright yellow solution.  The solution immediately changed to dark red in colour.  Gradually, it was warmed to –30°C and PPh2Cl (0.52 mL, 2.89 mmol) was added.  The solution was warmed to room temperature overnight. The solution was then quenched with 50 mL of water.  The ether layer was removed in vacuo and the water was decanted.  The remaining residue was rinsed three times with water (~ 50 mL).  The residue was dissolved in minimal acetone and then sonicated with MeOH (~ 20 mL) resulting in a bright orange oily residue at the bottom in the flask. The orange oil was then left under vacuum overnight, giving orange P2T5 powder.  Yield: 316 mg, 30%. 1 H NMR (300 MHz, CDCl3); δ 7.36 (m, 20H), 7.13 (d, 2H, J = 5.1 Hz), 7.10 (s, 2H), 6.88 (d, 2H, J = 5.1 Hz), 6.57 (s, 2Hz), 2.58 (t, 4H, J = 7.8 Hz), 1.25 (m, 16H), 0.89 (m, 6H). 31 P{ 1 H} NMR (121 MHz, CDCl3) δ -23.8 ppm. EI-MS m/z 946 (40%, [M] + ), 930 (90%, [M – CH3] + ), 780 (90%, [M- C12H26] + ), 764 (100%, [M-PPh2] + ). Anal. Calcd for C56H54P2S5: C, 70.85; H, 5.73; N, 0.00. Found: C, 70.98; H, 5.50; N, 0,05.  26  3,3´´-Bis(trimethylsilylacetylene)-2,2:5´,2´´-terthiophene (TMS2-A2T3, 64). A degassed piperidine solution (50 mL) of Br2T3 (1.160 g, 2.86 mmol), trimethylsilylacetylene (10.1 g, 102.8 mmol), Pd(PPh3)4 (330 mg, 0.29 mmol) and CuI (59.8 mg, 0.314 mmol) were heated to reflux in the dark for 5 days.  After cooling the reaction to room temperature, 50 mL of Et2O was added and the mixture was washed five times with 50 mL of H2O.  The Et2O was then removed in vacuo leaving a brown oil.  The oil was partially purified via column chromatography on silica with hexanes as the eluent.  The resulting red oil (1.18 g) contained some silyl methyl impurities that were difficult to remove, and the compound was used as is in the subsequent reaction.  When a sample of the oil was dissolved in hexanes at –4ºC and left for three months, pure yellow TMS2-A2T3 slowly precipitated from the solution. 1 H NMR (300 MHz, CDCl3); δ 7.61 (s, 2H), 7.08 (d, 2H, J = 5.1 Hz), 7.06 (d, 2H, J = 5.4 Hz), 0.31 (s, 18H). 13 C{ 1 H} NMR (75 MHz, CDCl3); δ 136, 132, 126, 118, 101, 0, no acetylene resonances were observed in the 13 C NMR spectrum.  EI-MS m/z 440 (100%, [M] + ). Anal. Calcd for C22H24Si2S3: C, 59.95; H, 5.49; N, 0.00. Found: C, 59.66; H, 5.73; N, 0.31.  3,3´´-Bis(acetylene)-2,2:5´,2´´-terthiophene (A2T3, 59). A THF solution of n-Bu4NF (1 M, 5.9 mL) was added to a stirring THF solution (50 mL) of TMS2-A2T3 (1.18 g, 2.68 mmol).  The solution immediately changed from yellow to dark brown and was stirred overnight.  The THF was then removed in vacuo and the subsequent residue was dry loaded on a silica column and purified with an acetone/hexanes (1:2) eluent. A2T3 was collected as a yellow solid.  Yield: 512 mg, 65%.  Crystals suitable for X-ray diffraction were grown from CH2Cl2/hexanes solution. 1 H NMR (300 MHz, CDCl3); δ 7.51 (2, 2H), 7.11  (q, 4H, J = 5.1 Hz), 3.43 (s, 2H). 13 C{ 1 H} NMR (100 MHz, CDCl3) δ 140, 136, 132, 126, 123, 117, 82, 79.  IR 2100.3 cm -1  (ν(C≡C)). EI-MS m/z 296 (100%, [M] + ). Anal. Calcd for C16H8S3: C, 64.83; H, 2.72. Found: C, 64.54; H, 2.75.  Section 2.2.3 – X-Ray Crystallography All crystals were mounted on glass fibers.  The crystal structures were obtained and solved by Dr. B. O. Patrick. All measurements were made on a Bruker X8 APEX II  27 diffractometer with graphite monochromated Mo-Kα radiation. Data were collected and integrated using the Bruker SAINT 106  software package. Data were corrected for absorption effects using the multi-scan technique (SADABS 107 ).  The data were corrected for Lorentz and polarization effects.  The structures were solved by direct methods. 108  Diagrams were made using ORTEP-3, 109  and POV-RAY. 110   P2T3 (57). All data were collected to a maximum 2θ value of 56.1°.  Data were collected in a series of φ and ω scans in 0.50° oscillations with 20.0-second exposures. The crystal-to-detector distance was 36.00 mm. Of the 24614 reflections that were collected, 7094 were unique (Rint = 0.050); equivalent reflections were merged.  The minimum and maximum transmission coefficients were 0.884 and 0.989, respectively.  All non-hydrogen atoms were refined anisotropically.  All hydrogen atoms were placed in calculated positions but were not refined. The final cycle of full-matrix least-squares refinement on F 2  was based on 7094 reflections and 370 variable parameters and converged.  A2T3 (59). All data were collected to a maximum 2θ value of 55.0°.  Data were collected in a series of φ and ω scans in 0.50° oscillations with 10.0-second exposures. The crystal-to-detector distance was 36.00 mm. Of the 18307 reflections that were collected, 3066 were unique (Rint = 0.040); equivalent reflections were merged. The minimum and maximum transmission coefficients were 0.812 and 0.975, respectively.  All non-hydrogen atoms were refined anisotropically.  All hydrogen atoms were placed in calculated positions but were not refined. The final cycle of full-matrix least-squares refinement on F 2  was based on 3066 reflections and 172 variable parameters and converged.   28 Section 2.3 – Results and Discussion  Section 2.3.1 – Synthesis The synthesis of Br2T3 has previously been reported. 104  There were several slight modifications to the literature synthesis of Br2T3 used here (Scheme 2-1).  The high toxicity associated with alkyl-tin reagents 111  inspired changing the Stille coupling previously used to generate T3 to a Kumada coupling. 103  Additionally, Br2 was previously used to synthesize Br4T3, here NBS was chosen instead as the brominating agent.  Finally, in the last step, the concentration was changed from 0.07 M in EtOH/AcOH/H2O/HCl (0.69:0.23:0.08:0.004) to 0.035 M in the same proportions of EtOH/AcOH/H2O/HCl.  The lower concentration gave a quantitative yield of Br2T3 and thereby eliminated the crystallization step reported in the literature. Increased π conjugation in organic molecules typically increases the molar absorptivity and lowers the oxidation potential, which can be beneficial in photovoltaic applications and in facilitating the electropolymerizability of a molecule.  To lengthen the π-conjugation in Br2T3, Br2T5 was made by an additional two steps.  First iodination of both α-positions of Br2T3 with NIS, resulted in I2Br2T3. This was followed by a Suzuki coupling of I2Br2T3 with 2-(3-hexyl-2- thienyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 105  to result in Br2T5.   29 Scheme 2-1.   P2T3 and P2T5 were synthesized from Br2T3 and Br2T5 respectively.  Synthesis of P2T3 and P2T5 was carried out via addition of n-BuLi to the appropriate dibromo starting material at -78°C, followed by addition of PPh2Cl at -30°C in diethyl ether as shown in Scheme 2-2. Diethyl ether is essential in this synthesis since lithiation of brominated thiophenes in THF at low temperatures is known to result in the “halogen dance” 112  that often yields multiple products that are difficult to separate.  After phosphination, water was added to quench the reaction and neither P2T3 nor P2T5 required chromatography for purification.  30  Scheme 2-2.   A2T3 was synthesized from the same halogenated precursor (Br2T3) as used to make P2T3. The first step involved a Sonagashira coupling similar to that reported previously 113  to exchange the bromo groups for TMS-acetylene as shown in Scheme 2-3.  The TMS group was then deprotected using the base n-Bu4NF in THF to yield A2T3.  Scheme 2-3.   Section 2.3.2 – Solid-State Molecular Structures Further confirmation of the structures of P2T3 and A2T3 was obtained from single crystal X-ray structures.  Packing and π interactions are of interest, but the interannular torsion angle is particularly noteworthy in these molecules.  The torsion angle indicates the degree of π-orbital  31 overlap and hence gives an approximation of the conjugation of the oligothiophene in the solid- state. Crystals of P2T3 were obtained from CDCl3/acetone/CH2Cl2 solution (Figure 2-1).  The phosphine and terthiophene bond lengths and angles are typical for triphenylphosphine114 and terthiophene115 (Table 2-1).  The molecule packs with unexceptional edge-to-edge and slipped π interactions between the aromatic moieties.  The steric bulk of the diphenylphosphine groups of P2T3 cause the phosphine substituents to be on either side of the terthiophene backbone. Therefore the central thiophene in P2T3 is syn and anti to the S atom of the terminal thiophenes. This is unlike unsubstituted terthiophene where the terminal thiophene S atoms are both anti to the central thiophene S.  The steric bulk also influences the conjugation along the terthiophene in P2T3, as evident by the torsion angles of 149.65(15)° and 17.7(3)°. These are greater than for terthiophene that ranges from 6-9° in the solid-state,115  but similar to the lowest energy conformation calculated for terthiophene of 147.2°.116   Figure 2-1.  Solid-state molecular structure of P2T3 (57).  Thermal ellipsoids are drawn at 50% probability, and H atoms are omitted for clarity.   32 By contrast, in the solid-state A2T3 is very similar to terthiophene (Figure 2-2).  Crystals suitable for single crystal X-ray diffraction were obtained from CH2Cl2/hexanes solution.  All bond lengths and angles of A2T3 are typical for terthiophene 115 and acetylene species117 (Table 2-2).  The acetylene functionality imposes less steric bulk on the terthiophene than the aryl phosphines in P2T3 allowing the acetylenes to be oriented cis to one another.  The terminal thiophenes both have their S atoms anti to the central thiophene and the terthiophene is nearly planar with torsion angles of 175.80(11)° and 171.47(10)°.  A2T3 also packs in a herringbone conformation, like terthiophene.115   Figure 2-2.  a) Solid-state molecular structure of A2T3 (59).  Thermal ellipsoids are drawn at 50% probability and H atoms are omitted for clarity.  b) Solid-state packing of A2T3 (59) looking down the c-axis.  33  Table 2-1.  Selected bond lengths (Å) and angles (°) for P2T3 (57). Bond lengths (Å) C1-C2 1.343(4) C1-S1  1.707(3) C2-C3 1.429(3) C3-C4 1.376(3) C4-C5  1.453(3) C4-S1 1.738(2) C3-P1 1.830(2) Angles (º) C2-C1-S1  112.0(2) C1-C2-C3 114.2(2) C4-C3-C2 110.7(2) C4-C3-P1 123.02(18) C2-C3-P1 125.90(19) C3-C4-S1 111.58(18) C3-P1-C19 103.19(11) C3-P1-C13 101.58(11) C19-P1-C13 100.07(11) C1-S1-C4 91.49(12) Torsion Angles (º) S1-C4-C5-S2 -149.65(15) S2-C8-C9-S3 17.7(3)   Table 2-2.  Selected bond lengths (Å) and angles (°) for A2T3 (59). Bond lengths (Å) C1-C2  1.339(3) C1-S1 1.711(3) C2-C3 1.429(3) C3-C4 1.375(3) C4-C5 1.450(3) C4-S1 1.726(2) C3-C13 1.428(3) C13-C14 1.172(3) Angles (°) C2-C1-S1 112.36(18) C1-C2-C3 112.6(2) C4-C3-C13 124.60(19) C4-C3-C2 112.6(2) C13-C3-C2 122.8(2) C3-C4-S1 110.36(15) C1-S1-C4 92.05(11) C14-C13-C3 179.5(3) Torsion Angles (º) S1-C4-C5-S2 175.80(11) S2-C8-C9-S3 171.47(10)   34 Section 2.3.3 – Electronic Absorption Spectra The lowest energy bands in the absorption spectra of oligothiophenes are from ππ* transitions, the energy of which depends on substituents on the oligothiophene and the conjugation length.  The electronic absorption spectra of oligothiophenes synthesized in this thesis and related compounds are given in Table 2-3.  Table 2-3.  Electronic absorption maxima of oligothiophenes. Compound λmax/nm (ε/M -1cm-1) T3 (2) 354 (22 080) a T5 (4) 417 (42 670) a Br2T3 (60) 260 (11 000), 350 (22 000) I2Br2T3 (62) 245 (11 000), 370 (25 000) Br2T5 (63) 265 (16 200), 404 (30 500) P2T3 (57) 253 (18 000), 360 (12 000) P2T2 (54) 252 (sh) (16 500) b (PO)2T3 (61) 260 (14 000), 350 (14 000) (PO)2T2 (66) 254 (16 500), 286 (sh) (6 290) b P2T5 (58) 406 (31 900) A2T3 (59) 275 (8 000), 385 (21 000) α−A2T3 (45) 394 (31 000) c PT3 (41) 254 (20 800), 354 (17 700) d PT5 (56) 251 (21 300), 349 (sh) (14 700), 406 (33 600) e Spectra recorded in CH2Cl2 at 296 K.  a From Ref.118  Recorded in dioxane.b From Ref.88 (PO)2T2 = 3,3´-bis(diphenylphosphoryl)-2,2´-bithiophene cFrom Ref.89 dFrom Ref.93 eFrom Ref.94  The ππ* absorption band of P2T3 is red-shifted by less than 10 nm from the corresponding absorption band of T3 and PT3. Previous work showed that phosphine substituents  35 could sterically affect the conjugation of oligothiophenes and shift the ππ* absorption bands.88 Steric factors are likely responsible for the minimal change in absorbance of P2T3 with respect to T3. Oxidizing the phosphine to give (PO)2T3 results in an absorption band slightly blue-shifted from that of P2T3.  Previous studies with P2T2 have observed a red-shift of the lowest energy absorption band upon oxidation to (PO)2T2. 88  By contrast, the extended conjugation afforded by the acetylene groups in A2T3 result in the lowest energy band bathochromically shifting by ~30 nm from T3 (Figure 2-3).  Similarly, the longer conjugation length in α-A2T3 shifts the lowest energy π absorption band to 394 nm.89 Increasing the conjugation length with two additional thiophene units in P2T5 causes the ππ* absorption band to bathochromically shift with respect to P2T3, as is observed when comparing T3 to T5.  Unlike the comparison of T3 with P2T3 though, the ππ* absorption band of P2T5 is hypsochromically shifted by ~10 nm from T5.  This suggests that the conjugation of P2T5 is slightly decreased relative to T5 and may indicate additional twisting along the pentathiophene chain of P2T5 as a result of the hexyl and aryl-phosphine substituents.  The lowest energy ππ* absorption band is also identical to that of PT5. 94   36  Figure 2-3.  Absorption spectra of P2T3 (57), P2T5 (58) and A2T3 (59) in CH2Cl2 at 298 K.  The absorption spectra of P2T3 and A2T3 were also obtained at 85 K (Figure 2-4).  P2T3 had almost no change in the lowest energy absorption band (λmax = 359 nm (298 K) vs λmax = 362 nm (85 K)) with cooling, whereas the absorption bands of A2T3 separated into several bands split by ~1400 cm-1 with the lowest energy band red-shifted by ~900 cm-1.  The absorption band of T3 red-shifts by ~1600 cm-1 upon cooling to 77 K118 and the single band observed at room temperature separates into sharp bands.118,119   The bathochromic shift of the bands in the T3 spectrum with temperature suggests a planarization of the backbone118 and this same effect could be responsible for the observed changes in A2T3. The separation into several bands indicates vibronic coupling of the ππ* absorption with the thienyl ring stretches for A2T3 and terthiophene.  Thiophene ring vibrations 120 and C-C stretches121 are typically observed near 1400 cm-1.  The lack of changes in the spectrum of P2T3 with decreasing temperature suggests that the conformation at low temperature is similar to that at room temperature.   Therefore the steric bulk of the phosphines likely prevent a planar structure of P2T3 even at 85 K.  Vibrational coupling and sharper band widths tend to occur with planar molecules.116  37  Figure 2-4.  Absorption spectra of a) A2T3 (59) and b) P2T3 (57) in MeOH/EtOH (1:4) at 85 K and 298 K.   38 The colour of P2T5 in solution changes from orange to red in an NMR tube in the time required to get a 1H NMR spectrum, so it was not included in the variable temperature UV-vis studies.  All of the absorption and emission data for P2T5 were obtained under a N2(g) atmosphere.  1H and 31P{1H} NMR spectra were taken over several hours (Figure 2-5) to qualitatively study the nature of this colour change.  The chemical shifts of the aromatic resonances in the 1H NMR spectrum clearly change with time.  The largest shifts occur for the phenyl groups of the aryl-phosphine substituents, suggesting that the phosphine is affected more than the pentathiophene moiety.  The 31P{1H} NMR spectrum also changes considerably.  The single resonance at –23 ppm diminishes after 4 hours and completely disappears after 23 hours. Two new chemical shifts appear at 21 and 29 ppm.  Peaks in this region are typical of oxidized aryl-phosphine derivatives.122 Predicting the colour of oxidized phosphino-thiophene derivatives may be difficult since (PO)2T3 is hypsochromically shifted from P2T3, whereas (PO)2T2 is bathochromically shifted from P2T2.  Since P2T5 gradually becomes more red, the lowest energy absorption band of oxidized P2T5 may be red-shifted with respect to P2T5 and the colour change indicates that P2T5 is easily oxidized with air.  The EI-MS is also consistent with the presence of oxidized (PO)2T5. Alternatively, trace decomposition species from P2T5 not observed in the 1H and 31P{1H} NMR may have very large molar absorptivities, which are bathochromically shifted from P2T5 and cause the change in colour.   39  Figure 2-5.  a) 300 MHz 1H NMR spectra of aromatic region of P2T5 (58) and b) 121 MHz 31P{1H} NMR spectra of P2T5 (58) at 0, 4, and 23 hours in CDCl3.   40 The distance between phenyl rings in phosphine containing complexes can influence their emissive properties and these differences can be induced by grinding.123 In order to study the emissive properties, the absorption properties of P2T3 were first studied.  The solid-state absorption spectrum of P2T3 was obtained before and after grinding as shown in Figure 2-6. Immediately after grinding P2T3, the band at 492 nm disappeared and only the band at 380 nm remained.  This change is temporary and the new absorption band decreases within twenty minutes and the band at 492 nm grows back in.  This could indicate that some P2T3 is oxidized on the surface and scratching the surface merely exposes some of the non-oxidized material. Alternatively, scratching could decrease the conjugation along the terthiophene that causes a hypsochromic shift in the absorption band until the terthiophene backbone relaxes to its more planar state.   Figure 2-6.  Absorption spectra of P2T3 (57) powder and changes with grinding and time.    41 Section 2.3.4 – Emission Spectra Emission spectra of the molecules were obtained to gain further insight into their electronic properties.  Relevant emission bands are given in Table 2-4.  Table 2-4.  Emission maxima and quantum yields of oligothiophenes. Compound λmax/nm Φem T3 (2) 407, 426 a 0.056a T5 (4) 482, 514 a - Br2T3 (62) 412, 431 - I2Br2T3 (64) 429, 453 - Br2T5 (65) 488, 517 - P2T3 (60) 449, 468 0.06 (PO)2T3 (63) 445, 465 - P2T5 (60) 515, 546 - A2T3 (61) 438, 462  0.04 α-A2T3 (47) 446, 469 b - PT3 (52) 420 (sh), 422 c 0.0057c Spectra recorded in CH2Cl2 at 296 K.  aFrom Ref.118 Absorption spectra recorded in dioxane. bFrom Ref.89 cFrom Ref.124  Substitution on the terthiophene backbone resulted in a bathochromic shift in emission for all of the molecules studied.  This could be from an increase in conjugation through the substituent’s electronic interaction with the oligothiophene and/or from steric effects that increase the planarity of the terthiophene.  The emission quantum yields (Φem) of both P2T3 and A2T3 are comparable to that of T3. Unlike the absorption spectrum of P2T5, its emission band is red-shifted with respect to T5. The emission spectra of A2T3 and P2T3 were obtained at 85 K (Figure 2-7 and Figure 2-8).  At low temperature, A2T3 behaves like T3. 118,119 There are negligible shifts in the  42 fluorescence maxima and the excitation spectra mirror the emission.  This is consistent with emission occurring from a similar state as the one resulting from absorption.  Together with the red-shift in the absorption spectrum, this suggests that cooling results in a more planar conformation than in A2T3 at room temperature.  As in the absorption spectrum, the emission band exhibited vibronic coupling where the bands were separated by ~1400 cm-1.  The emission intensity of A2T3 also increased with decreasing temperature. Similarly, the 85 K emission spectrum of P2T3 showed minimal shift and its excitation spectrum matched its absorption spectrum.  There was also an increase in the emission intensity with decreasing temperature (Figure 2-7), which suggests that thermal vibrations result in radiationless deactivation pathways.  Unlike T3 or A2T3, there was no additional vibronic coupling apparent in the emission spectrum with decreased temperature.  Figure 2-7.  Emission (λex = 360 nm) and excitation (λem = 445 nm) spectra of P2T3 (57) in MeOH/EtOH (1:4) showing the decreasing luminescence intensity with increasing temperature.   43  Figure 2-8.  Emission spectra of a) P2T3  (57) and b) A2T3 (59) in MeOH/EtOH (1:4) at 85 K and 298 K.   44 As discussed in Section 2.3.3, grinding phenyl-phosphine complexes is known to result in changes in emission properties.123 The P2T3 emission spectrum, like its absorption spectrum, changes with grinding as it shifts from ~560 nm to ~490 nm (Figure 2-9).  This change is temporary and reverts back to its original emission when the sample is left overnight.  Although these changes could be a result of (PO)2T3 on the surface of the solid, the emission of (PO)2T3 (~520 nm) is blue-shifted with respect to the original emission band of unground P2T3 (Figure 2-10). Therefore another mechanism is likely responsible for the changes in emission, possibly a change in conjugation length. The hypsochromic shift in the emission spectrum and absorption spectrum of P2T3 with grinding suggest that grinding temporarily decreases the conjugation of P2T3 that relaxes back into a more planar conformation with time.   Figure 2-9.  Emission of several P2T3 (57) samples.   45  Figure 2-10. Emission of ground P2T3 (57) and (PO)2T3 (61).  Section 2.3.5 – Electrochemistry Substituted oligothiophenes have been electropolymerized to give functional materials such as catalysts125 and cathodes for batteries.126  Electropolymerizability of an oligothiophene is affected by substituents and length of conjugation.127 The oxidation potential of some relevant oligothiophenes are given in Table 2-5.   46  Table 2-5.  Oxidation potentials of relevant oligothiophenes. Compound E1/2 +/0 vs SCE T3 (2) 0.98 vs SCE a T5 (4) 0.97 (vs. Ag/AgCl) b P2T2 (54) 1.10 c,d PT3 (41) 1.30 c,d P2T4 (55) 1.02 c,d P2T3 (57) 1.40, c 1.65c P2T5 (58) 0.72, 1.56 c A2T3 (59) 1.00 PT5 (56) 0.99, c 1.37c,d CVs recorded in CH2Cl2 with 0.1 M [n-Bu4N][PF6] and 1 mmol of P2T3, P2T5 or A2T3.  a From Ref.128 bFrom Ref.129 cIrreversible wave, Ep. dFrom Ref.124  The CVs of P2T3 and P2T5 (Figure 2-11) both show two irreversible oxidation waves. The first oxidation likely results in removal of an electron from the oligothiophene whereas the second wave may be removal of an electron from the aromatic phosphine.  Previous studies have shown the oxidation of PPh3 occurs at ~1.6 V. 124  When the potential range was scanned multiple times, the current at the working electrode decreased. The lack of increase in current indicates that neither P2T3 nor P2T5 electropolymerizes. Similarly, PT3 does not electropolymerize. 93 It is possible that the nucleophilic P centre may quench the reactive α-position of the terminal thiophenes, thereby preventing electropolymerization.93  47  Figure 2-11.  CVs of P2T3 (57) and P2T5 (58) on a Pt disk electrode (scan rate = 100 mV/s). Electrolyte = 0.1 M [n-Bu4N][PF6].  Solvent = CH2Cl2.  A2T3 shows notably different electrochemical properties.  A2T3 has a single oxidation wave at 1.00 V vs SCE.  Repetitive scanning of potential from –0.5 to 1.26 V resulted in an increase in current (Figure 2-12 (a)), which indicates that an electropolymerized film is depositing on the working electrode. Both acetylene derivatives and thiophenes have similar oxidation potentials.  For example, ethynyl benzene oxidizes at ~2 V130 and 3-ethylthiophene oxidizes at 1.82 V.131 Hence, poly-A2T3 may be linked through the thiophene or acetylene groups.  Poly-A2T3 is also electrochromic and changes in colour from orange at –0.5 V to blue at 1.2 V.  Several other polythiophene films also demonstrate electrochromic behaviour.132  48  Figure 2-12.  a) CV of A2T3 (59) showing its electropolymerization on a Pt disk electrode (scan rate = 100 mV/s).  Electrolyte = 0.1 M [n-Bu4N][PF6].  Solvent = CH2Cl2.  b) UV/vis absorption spectra of A2T3 (59) and poly-A2T3 (59).   49 Poly-A2T3 was further characterized via its absorption spectrum (Figure 2-12(b)).  The absorption spectrum of poly-A2T3 shows a much broader absorption band than A2T3, but there is very little shift in λmax.  The similar absorption maxima suggest that polymerization does not significantly increase the conjugation length of the polymer relative to the monomer and is consistent with the small change in the oxidation potential as the film polymerizes.  The broadness of the absorption band of poly-A2T3, is likely from solid-state interactions.  Section 2.4 – Conclusions  Two new bis-phosphines, P2T3 and P2T5, and a bis-acetylene, A2T3, were synthesized.  In the solid-state, it is evident that the aryl-phosphine moieties of P2T3 cause the terthiophene backbone to twist more than the less sterically demanding acetylene groups do in A2T3.  The steric demands of the bis-phosphine analogues causes smaller shifts in the absorption and emission spectrum than seen in other bis-phosphino-oligothiophenes with respect to their analogous unsubstituted oligothiophenes, likely because the additional thiophene bridging the two bulky groups results in less twisting of the oligothiophene backbone. Substitution with an acetylene increases the conjugation and planarity with respect to the bis-phosphine molecules and therefore A2T3 has red-shifted absorption and emission spectra.  It was also found that P2T3 absorption and emission spectra change with grinding, possibly as a result of a change in conjugation.  The substituents affect the electrochemical properties; both phosphines did not electropolymerize whereas A2T3 electropolymerizes into a conducting film.  50 CHAPTER 3 GOLD(I)-PHOSPHINE COMPLEXES∗  Section 3.1 Introduction  Gold complexes are often studied for their catalytic 133,134 or luminescence properties. The luminescence of Au(I) complexes can be a result of Au-Au interactions.135,136  In materials chemistry, the luminescence of Au(I) complexes has been exploited with their incorporation in OLEDs,137 ion sensors138 and pressure sensors.139 The tendency of Au(I)-complexes to aggregate such that the Au(I) ions come in close proximity to one another is referred to as aurophilicity.  If the Au atoms are within 3.6 Å of one another, their van der Waals radii overlap such that a Au(I)-Au(I) interaction forms.140  This interaction can be described using the valence molecular orbitals (Figure 3-1).136  The empty 6pz orbital of the Au(I) mixes with the full 5dz2 orbitals that allows for a bonding interaction to form between Au(I) atoms (Figure 3-1), described as an “aurophilic interaction.”  Figure 3-1. Simplified molecular orbital diagram of an aurophilic interaction.  (Adapted from Ref.136)   ∗ Part of this chapter has been published.  Reproduced in part from Kuchison, A. M., Wolf, M. O., Patrick, B. O. (2009) Conjugated ligand based tribochromic luminescence. Chem. Commun., 7387-7389 (http://dx.doi.org/10.1039/b915089g) – reproduced with permission from The Royal Society of Chemistry.  51 Complexes with these interactions are particularly interesting since the energy difference, ∆ in Figure 3-1, can correspond to a visible wavelength.  Therefore, photoexcitation of compounds with aurophilic interactions can result in visible light emission.  The exact emission energy is difficult to predict since it depends on the ligands on the Au(I) complexes, the Au(I)- Au(I) distance and the number of overlapping Au(I) ions.  Ionic charges on Au(I) complexes also do not hinder formation of aurophilic interactions.  For example [Au(C(NHMe)2)2] +,141 [Au(CN)2] -,142 and PPhMe2AuCl 143 all have Au-Au interactions that causes these species to be emissive. Previous studies in the Wolf group of phosphino-oligothiophene Au(I) complexes used ligands with phosphines in the α- and β-positions (Chart 3-1).88,91  Au-Au interactions were observed for complexes 67,88 68,88 69,91 and 72.91  When the Au(I) ions were coordinated via β- phosphines, the intramolecular Au-Au interaction increased the torsion angle between adjacent thiophenes in the backbone relative to the oxidized phosphine.88 Intermolecular Au-Au interactions were observed in α-phosphino-oligothiophenes and emission from the Au-Au interaction and/or the oligothiophene was observed.91  The emission depends on the other ligands present on the Au (whether I- or Cl-) and the conjugation length of the oligothiophene. Complexes 69 and 72 showed emission from the Au-Au interaction, but for n>1 the emission was dominated by states on the oligothiophene backbone.91  Chart 3-1.  Ref.88,91    Aurophilic interactions in the solid-state can also be influenced by grinding of the solid sample, to change the luminescence properties.139,144-147 This type of luminescence change that is elicited from applying a mechanical force to a material is known as tribochromic144 or mechanochromic luminescence.139 Other intermolecular forces such as π-interactions, hydrogen bonding and metal-metal interactions148,149 can be responsible for the changes in solid-state  52 luminescence. Chemical reactions144 and solid-state defects147 induced by grinding are also possible causes for changes in solid-state emission. Chemical reactions accompanied by changes in aurophilic interactions upon grinding were observed with the Au(I)-thiouracilate (73) (Scheme 3-1).144 Grinding the non-emissive powder of 73 causes cyan-coloured photoemission. This change is a result of 73 releasing CF3COOH that allows more extensive Au(I)-Au(I) interactions.  Scheme 3-1.  Ref.144   Changes from crystalline to amorphous phases are also known to influence emissive properties of Au(I) and Ag(I) complexes.123,139 Grinding microcrystalline 74 (Chart 3-2) causes the material to change to an amorphous phase.139 This accompanies a change in emissive properties; the microcrystalline material has blue photoemission whereas the amorphous material has yellow photoemission.139 The authors attributed the luminescence change to the reduced distance between Au(I) centres.139 Tsukuda also found that changes from crystalline to amorphous phases influenced the emissive properties of a Ag(I) complex.123 The emission of 75 (Chart 3-2) changed from blue to green upon grinding.123 Changes in the intermolecular distance between phenylene groups brought about by grinding allowed this luminescence colour change.123  Chart 3-2.  Ref.123,139   53 Pressure is also known to cause changes in properties of organic molecules.  Poly-(3- alkylthiophenes) are piezochromic.150,151 Under constant applied pressure, these polymers planarize and there is a red-shift in the absorption band.150,151 Temporary pressure from grinding is also known to elicit permanent colour changes in sterically congested molecules.152 As mentioned, tethering Au(I) centres to β-phosphino-oligothiophenes has previously been shown to cause twisting in the oligothiophene backbone due to aurophilic interactions. Whether having a single Au(I) or two Au(I) ions tethered to phosphino-terthiophenes could yield similar distortions in conjugation with or without aurophilic interactions was of interest and the complexes in Chart 3-3 were chosen for study.   (AuCl)PT3 and (AuSPh)PT3 were previously synthesized and characterized,153 the remainder of the complexes were prepared by me.  When there was a significant difference between the absorption spectra of the complex and the free ligand, the photophysical properties were further studied in the solid-state.  In particular, whether grinding a sample of a complex could cause tribochromic luminescence from either the terthiophene backbone or an aurophilic interaction was studied.  Chart 3-3.    54 Section 3.2 – Experimental  Section 3.2.1 – General (AuCl)tht and [n-Bu4N][Au(CN)2] were prepared according to literature procedures. 154,155 (AuCl)PT3 and (AuSPh)PT3 were previously prepared and characterized. 153 AgNO3, pentafluorobenzenethiol and p-methoxybenzenethiol were purchased from Sigma-Aldrich. HAuCl4 was purchased from Strem Chemicals, [n-Bu4N][PF6] was purchased from Fluka Chemicals. 1H  NMR spectra were collected on either a Bruker AV-300 spectrometer or Bruker AV- 400 spectrometer.  1H NMR spectra were referenced to residual solvent and 31P{1H} NMR spectra referenced to external 85% H3PO4.  Infrared spectra were obtained on a Nicolet 6700 FTIR with a Smart Orbit™ accessory.  Solution UV-vis absorption spectra were obtained on a Varian Cary 5000 UV-vis-near-IR spectrophotometer.  Solution excitation and emission spectra were obtained on a Photon Technology International QuantaMaster fluorimeter and were uncorrected for lamp intensity.  Powder absorption spectra of (AuCl)2P2T3 were obtained using an Ocean Optics SD2000 fiber optics spectrometer with a DH-2000 mikropack UV-Vis-NIR light source.  For these measurements, the (AuCl)2P2T3 was diluted with MgO (~1 mg of (AuCl)2P2T3 in 50 mg of MgO).  Raman spectra were carried out using a Renishaw System 1000 confocal microscope with a 785 nm diode laser source and charge-coupled device (CCD) detector.  Spectra were collected for 30 s from 350-1800 cm-1 using 1% laser power.  Powder XRD (PXRD) data were recorded on a Bruker D8 Advance diffractometer with graphite monochromated Cu Kα radiation. The (AuCl)2P2T3 powder used for the PXRD was crushed after the measurement on a zero background silicon wafer and a diffractogram was then obtained.  Section 3.2.2 – Procedures  (AuSC6F5) PT3 (78). AuPT3Cl (100 mg, 0.15 mmol) was dissolved in THF (4 mL) and pentafluorobenzenethiol (0.4 M THF solution, 0.4 mL, 0.15 mmol) and triethylamine (0.4 M THF solution, 0.4 mL, 0.15 mmol) was added dropwise under a N2(g) atmosphere.  The solution was stirred for one hour, during which time a white precipitate was formed.  The THF was  55 removed in vacuo and the residue was washed three times with water (3 × 3 mL).  The residue was dissolved in CHCl3/hexanes and off-white crystals were obtained.  These crystals were washed with cold CHCl3, yielding crystals suitable for single crystal X-ray analysis.  Yield:  62.0 mg, 50%. 1H NMR (CDCl3, 300 MHz): δ 7.55 (m, 10H), 7.22 (d, J = 4.8Hz, 2H), 7.09 (d, 1H, J = 3.6 Hz),  6.98 (dd, 1H, J = 3.6 Hz, J = 4.8 Hz), 6.86 (m, 2H), 6.51 (d, J = 3.6Hz, 1H); 31P{1H} NMR (121 MHz, CDCl3): δ 21.8; 19F NMR (282 MHz, CDCl3): δ -132.3 (m). Anal. Calcd. For C30 H17 S4AuF5P: C, 43.48; H, 2.15. Found: C, 43.33; H, 2.30.   (AuSC6H4OMe)PT3 (79). AuPT3Cl (100 mg, 0.15 mmol) was dissolved in THF (4 mL) and p-methoxybenzenethiol (0.4 M THF solution, 0.4 mL, 0.15 mmol) and triethylamine (0.4 M THF solution, 0.4 mL, 0.15 mmol) were added dropwise under a N2(g) atmosphere.  The solution was stirred for one hour, during which time a white precipitate formed.  The THF was removed in vacuo and the residue was rinsed three times with water (3 × 3 mL).  The remaining residue was dissolved in toluene and a pale yellow solid precipitated out.  Yield: 79 mg, 68%. 1H NMR (CDCl3, 300 MHz): δ 7.59 (m, 6H), 7.49 (m, 6H), 7.32 (dd, 1H, J = 4.5Hz, J = 1.8 Hz), 7.23 (m, 1H), 7.20 (d, 1H, J = 1.8Hz), 7.09 (dd, 1H, J = 3.6Hz, J = 0.9 Hz), 6.98 (dd, 1H, J = 5.1Hz, J = 3.6Hz), 6.93 (m, 2H), 6.61 (m, 1H), 6.52 (d, 1H, J = 3.6 Hz), 3.72 (s, 3H).  31P{1H} NMR (121 MHz, CDCl3): δ 20.8 (s). Anal. Calcd. For C31H24AuOPS4: C, 48.44; H, 3.15. Found: C, 48.06; H, 3.45.  (AuCl)2P2T3 (80). P2T3 (125 mg, 0.203 mmol) in CH2Cl2 (10 mL) was added to a stirring solution of CH2Cl2 (20 ml) containing AuCl(tht) (130 mg, 0.405 mmol).  After one hour, the CH2Cl2 was removed in vacuo, and a yellow residue remained.  The residue was dissolved in a minimal amount of CH2Cl2 and an equal amount of hexanes was added.  The mixture was left undisturbed overnight, and a white crystalline material was collected via vacuum filtration.  Yield: 97 mg, 44%.  1H NMR (300 MHz, CDCl3): δ 6.61 (m, 2H), 6.81 (s, 2H), 7.38 (d, 2H, J = 6.6 Hz), 7.48 (m, 20H).  31P{1H} (121 MHz, CDCl3): δ 15.1 (s).  TOF-MS m/z 1045 ([M-Cl] +).  Anal. Calcd for C36H26Au2Cl2P2S3·CH2Cl2: C, 38.10; H, 2.42.  Found: C, 38.05; H, 2.49.  To prepare ground 81, a powder of 81 was deposited on the surface of a quartz or glass slide.  Pressure was applied to this powder through either scratching it gently with a metal spatula (approximately equal in  56 force to scratching filter paper when obtaining a solid precipitate product) or another quartz slide was put on the other side of the powder to sandwich 81 and one quartz slide was twisted 180°.  [AuP2T3][NO3] (81). AuCl(tht) (104 mg, 0.324 mmol) and P2T3 (200 mg, 0.324 mmol) were dissolved in CH2Cl2 (12 ml) in the dark and left for 30 minutes.  AgNO3 (55 mg, 0.324 mmol) was then added and the reaction was left to stir in the dark overnight.  The solvent was then removed in vacuo and the residue dissolved in MeOH.  The MeOH solution was filtered through celite and the MeOH removed in vacuo.  A yellow residue remained to which Et2O was added to precipitate a bright yellow product which was vacuum filtered.  Yield: 233 mg, 82%.  1H NMR (400 MHz, CDCl3): δ 6.86 (d, 2H, J = 5.2 Hz), 6.96 (s, 2H), 7.46 (m, 8H), 7.58 (m, 14H). 31P{1H} (162 MHz, CDCl3): δ 27.2 (s).  ESI-MS m/z 813 (100%, [M-(NO3)] +).  Anal. Calcd for C72H52Au2N2O6P4S6·3(H2O): C, 47.90; H, 3.24; N, 1.55.  Found: C, 47.86; H, 3.34; N, 1.76.  (AuCN)2P2T3 (82). [Au(P2T3)]2[NO3]2 (90.3 mg, 0.0516 mmol) and [n-Bu4N][Au(CN)2] (25.8 mg, 0.0516 mmol) was dissolved in CH2Cl2 (11 ml).  Over one minute the solution changed from clear to cloudy.  The solution was filtered through glass wool and hexanes were added which resulted in a yellow precipitate. The yellow precipitate was vacuum filtered.  Although 1H NMR and 31P{1H} NMR spectroscopy suggested the precipitate was pure, the IR spectroscopy indicated some free AuCN was present, so a yield was not calculated.  After four months at 4°C, crystals suitable for X-ray diffraction and analytical analysis were grown from CH2Cl2/hexanes. 1H NMR (300 MHz, CDCl3): δ 6.60 (dd, 2H, J = 5.2 Hz and J = 3.4 Hz), 6.88 (s, 2H), 7.41 (dd, 2H, J = 5.1 Hz and J = 1.2 Hz), 7.51 (m, 20H).  31P{1H} (121 MHz, CDCl3): δ 22.0 (s).  Anal. Calcd for C38H26Au2N2P2S3: C, 42.95; H, 2.47; N, 2.64.  Found: C, 43.50; H, 2.65; N, 2.92. IR: 2140 cm-1 (ν(C≡N)).  Section 3.2.3 – X-Ray Crystallography The crystal structures of (AuCl)PT3 and (AuSPh)PT3 were previously obtained. 156 The crystal structures of (AuSC6F5)PT3 and (AuCN)2P2T3 were obtained by Dr. B. O. Patrick at  57 UBC.  The crystal structure of (AuCl)2P2T3 was obtained by Dr. M. J. Katz at Simon Fraser University.  Diagrams were made using ORTEP-3,109 and POV-RAY.110  (AuSC6F5)PT3 (78). A crystal of (AuSC6F5)PT3 was mounted on a glass fiber. All measurements were made on a Bruker X8 APEX II diffractometer with graphite monochromated Mo-Kα radiation.  The data were collected to a maximum 2θ value of 56.4°. Data were collected in a series of φ and ω scans in 0.50° oscillations with 5.0 second exposures. Of the 27014 reflections that were collected, 6858 were unique (Rint = 0.038); equivalent reflections were merged.  Data were collected and integrated using the Bruker SAINT106 software package. Data were corrected for absorption effects using the multi-scan technique (SADABS)107, with minimum and maximum transmission coefficients of 0.210 and 0.326, respectively.  The structure was solved by direct methods.157 All non-hydrogen atoms were refined anisotropically, while all hydrogen atoms were placed in calculated positions and not refined.  The final cycle of full-matrix least-squares refinement on F2 was based on 6858 reflections and 371 variable parameters and converged. Neutral atom scattering factors were taken from Cromer and Waber.158 Anomalous dispersion effects were included in Fcalc; 159 the values for ∆f' and ∆f" were those of Creagh and McAuley.160 The values for the mass attenuation coefficients are those of Creagh and Hubbell.161 All refinements were performed using the SHELXTL162 crystallographic software package of Bruker-AXS.  (AuCl)2P2T3 (80). A crystal of (AuCl)2P2T3·CH2Cl2 was placed on the tip of a mitegen micromount with paratone® oil.  Data was collected in the range 3° ≤ 2θ ≤ 63° on a Bruker SMART diffractometer equipped with an APEX II CCD detector and a graphite monochromated Mo Kα sealed X-ray tube operating at 1.5 kW (50 kV, 30 mA).  The data were corrected by integration for the effects of absorption with a transmission range 0.490 – 0.746.  Final unit-cell dimensions were determined on the basis of 9991 well-centred reflections with range 4° ≤ 2θ ≤ 63°. The programs used for the absorption correction, and data reduction were from the Bruker APEX II Crystal Structure System.  The structure was solved with Sir92 and refined  58 using CRYSTALS.163 Complex scattering factors for neutral atoms were used in the calculation of structure factors.  (AuCN)2P2T3 (82).  A crystal of (AuCN)2P2T3·2CH2Cl2 was mounted on a glass fiber. All measurements were made on a Bruker X8 APEX II diffractometer with graphite monochromated Mo-Kα radiation.  The data were collected to a maximum 2θ value of 50.0º. Data were collected in a series of φ and ω scans in 0.50º oscillations with 30.0-second exposures.  Of the 20748 reflections that were collected, 7224 were unique (Rint = 0.043); equivalent reflections were merged.  Data were collected and integrated using the Bruker SAINT164 software package. Data were corrected for absorption effects using the multi-scan technique (SADABS),107 with minimum and maximum transmission coefficients of 0.345 and 0.414, respectively.  The data were corrected for Lorentz and polarization effects. The structure was solved by direct methods.157   The material crystallizes with two molecules of CH2Cl2 in the asymmetric unit. All non-hydrogen atoms were refined anisotropically.  All hydrogen atoms were placed in calculated positions but were not refined.  The final cycle of full-matrix least-squares refinement on F 2  was based on 7224 reflections and 478 variable parameters and converged.  The standard deviation of an observation of unit weight was 1.03. The weighting scheme was based on counting statistics. The maximum and minimum peaks on the final difference Fourier map corresponded to 1.85 and –1.23 e-/Å3, respectively. Neutral atom scattering factors were taken from Cromer and Waber.158 Anomalous dispersion effects were included in Fcalc; 159 the values for ∆f' and ∆f" were those of Creagh and McAuley.160 The values for the mass attenuation coefficients are those of Creagh and Hubbell.161 All refinements were performed using the SHELXTL162 crystallographic software package of Bruker-AXS.   59 Section 3.3 – Results and Discussion  Section 3.3.1 – Synthesis and Design  Previous Au-thienyl phosphine complexes, 67 and 68 elicited significant structural changes in the oligothiophene backbone as a result of an intramolecular Au-Au interaction.88  To determine if one Au(I) centre tethered to an oligothiophene via a β-phosphine substituent could electronically influence an oligothiophene backbone, O. Clot (UBC) and Y. Akahori (SFU) synthesized (AuCl)PT3 as shown in Scheme 3-2.  Scheme 3-2.   (AuCl)PT3 did not exhibit any intermolecular Au-Au interactions.  By contrast, Au(I) complexes with phosphines in the α-position of oligothiophenes displayed Au-Au interactions in the solid-state.  Replacing Cl groups with thiolates in Au(I)-phosphine complexes can induce Au-Au interactions.165 Three thiolates were chosen to replace Cl in (AuCl)PT3: benzenethiolate (previously synthesized by Y. Akahori (SFU) and O. Clot (UBC)), pentafluorobenzenethiolate, and p-methoxybenzenethiolate.  Addition of the selected thiol with NEt3 in CH2Cl2 to (AuCl)PT3 resulted in the formation of (AuSR)PT3 (R = C6H5, C6F5, p-C6H4OCH3) (Scheme 3-3).   60 Scheme 3-3.    To further probe the effects of Au(I) coordination on β-phosphino-oligothiophenes, P2T3 was used to bridge two Au(I) centres in (AuCl)2P2T3 (Scheme 3-4).  Addition of AuCl(tht) to P2T3 in CH2Cl2 yielded (AuCl)2P2T3 which was purified by crystallization from CHCl3/CH2Cl2/hexanes.  Aurophilic interactions can be enforced by using ligand precursors that encourage a cyclic structure and force Au(I) ions into close proximity.  For example, [Au4(µ- dppm)2(µ-L)2] (L = p-diisocyanobenzene) has a macrocyclic structure that results in aurophilic interactions.166  It was attempted to bridge two Au(I) centres via a cyclic Au(I)-P2T3 complex. Reaction of AuCl(tht) with AgNO3 and P2T3 yielded a complex with a formula consistent with the presence of one Au(I) centre per P2T3 molecule. Attempts to crystallize this complex were unsuccessful and the molecular structure of this putative [AuP2T3][NO3] complex is unknown.   61 Scheme 3-4.    Addition of [n-Bu4N][Au(CN)2] to 81 resulted in the formation of (AuCN)2P2T3 (Scheme 3-5).  Although this reaction appeared quantitative by 1H NMR and 31P{1H} NMR spectroscopy, the IR spectrum showed a band at 2230 cm-1 that indicated that some AuCN was present.167  In addition pure crystals of (AuCN)2P2T3 were colourless, but the powder obtained from these reactions was always bright yellow like AuCN.  Pure (AuCN)2P2T3 was obtained for analysis by single crystal XRD and EA after four months at 4°C in hexanes/CH2Cl2.  Several other cyano- Au(I) phosphine complexes have shown ligand scrambling reactions in solution,168 which causes difficulties in obtaining pure complexes.  Scheme 3-5.     62 Section 3.3.2 – Solid-State Molecular Structures Previously, Clot and Akahori obtained single crystals of (AuCl)PT3 and (AuSPh)PT3 (Figure 3-2).156 The bond lengths and angles were comparable to those in PPh3AuCl, 169 PPh3AuSPh 165 and terthiophene115 (Table 3-1 and Table 3-2).  Incorporation of the thiolate ligand did not induce any Au-Au interactions in the solid-state.  By contrast, PPh3AuCl does not have solid-state aurophilic interactions,169 but PPh3AuSPh does. 165 Changing the electronic properties of the thiolate by using the electron withdrawing pentafluorobenzenethiol also did not induce any Au-Au interactions. Similarly, PPh3AuSC6F5 170 has no Au-Au interactions present in the solid-state molecular structure.   Only twinned crystals of (AuSC6H4OMe)PT3 were obtained, the structure of which could not be solved.  The significant steric bulk imposed by the PT3 ligand may prevent any close contact of Au centres in the crystallized compounds.  As mentioned in Chapter 2, the torsion angle between thiophene rings is important in dictating the electronic properties of these complexes.  This angle varies slightly between (AuCl)PT3, (AuSPh)PT3 and (AuSC6F5)PT3 (Table 3-1, Table 3-2 and Table 3-3).  Notably, the torsion angle between the thiophene rings A and B varies more significantly than between thiophene rings B and C (Figure 3-3).  Interestingly, the terminal thiophenes closest to the Au centre for each complex have a Au-C distance of 3.30, 3.38, and 3.29 Å for (AuCl)PT3 (Au1- C4), (AuSPh)PT3 (Au1-C4) and (AuSC6F5)PT3 (Au1-C9) respectively.  This is longer than the Au-C distances observed in neutral Au(I) complexes with bulky aryl-phosphine ligands, where the average Au-C distance was 3.15 Å.171   63  Figure 3-2.  Solid-state molecular structures of a) (AuSC6F5)PT3 (78), b) (AuCl)PT3 (76), c) (AuSPh)PT3 (77).  Thermal ellipsoids drawn at 50% probability and H atoms omitted for clarity.  64  Figure 3-3.  Thiophene ring labels and corresponding S ring assignments in the X-ray structures.  Table 3-1.  Selected bond lengths and angles for (AuCl)PT3 (76). Bond lengths (Å) Au-Cl 2.2792(18) Au-P 2.2265(14) S1-C1 1.641(8) S1-C4 1.691(6) P-C6  1.811(6) C1-C2  1.329(13) C2-C3  1.439(10) C3-C4 1.477(7) Angles (º) Cl-Au-P 176.18(6) C1-S1-C4 93.5(4) S1-C1-C2 113.3(6) C1 C2 C3 116.2(7) C2-C3-C4      105.4(5) S1-C4-C3 111.6(4) Au-P-C6  110.38(18) Au-P-C21 116.09(18) Au-P-C31 113.02(17) Torsion Angles (º) S1-C4-C5-S2 50.3(7) S2-C8-C9-S3 -166.3(4)   65   Table 3-2.  Selected bond lengths and angles for (AuSPh)PT3 (77). Bond lengths (Å) Au-S4 2.2853(23) Au-P 2.2540(19) S1-C1 1.652(13) S1-C4 1.684(10) P-C6 1.800(9) C1-C2 1.299(22) C2-C3 1.437(13) C3-C4 1.448(13) Angles (º) S4-Au-P 177.21(8) Au-S4-C41 104.4(3) S1-C1-C2 113.0(8) C1-C2-C3  115.7(10) C2-C3-C4 107.1(9) S1-C4-C3 110.5(5) Au-P-C6 113.6(3) Au-P-C21 115.53(25) Au-P-C31    110.29(23) Torsion Angles (º) S1-C4-C5-S2 51(1) S2-C8-C9-S3 153.8(6)   Table 3-3.  Selected bond lengths and angles for (AuSC6F5)PT3 (78). Bond lengths (Å) P1-Au1 2.2430(8) S4-Au1 2.2806(9) C9-S3 1.711(3) C12-S3 1.682(4) C11-C12 1.344(5) C11-C103 1.442(4) C9-C103 1.427(4) C7-P1 1.801(3) Angles (º) P1-Au1-S4 172.19(3) C41-S4-Au1 107.38(11) C103-C9-S3 112.5(2) C11-C12-S3 113.1(3) C12-C11-C103 114.5(3) C9-C103-C11 107.9(3) C7-P1-Au1 112.79(10) C21-P1-Au1 115.59(11) C31-P1-Au1 110.64(10) Torsion Angles (º) S1-C4-C5-S2 146.2(2) S2-C8-C9-S3 -60.0(3)  66    Incorporation of two phosphine groups on a terthiophene with two Au(I) centres in (AuCl)2P2T3, minimally changed the torsion along the oligothiophene chain.  This was evident from the torsion angles that varied between 51(1)° and 49(1)° (Figure 3-4, Table 3-4) in (AuCl)2P2T3.  The bond lengths and angles were comparable to those in PPh3AuCl 169 and terthiophene.115 Two crystallographically unique molecules of (AuCl)2P2T3 were present in the solid-state structure that had very similar bond lengths and angles (Table 3-4 and Appendix Table).  As with the AuPT3 complexes, no aurophilic interactions were observed.  The distance between the Au and the central thienyl carbons varied from 3.32 Å – 3.37 Å.   Figure 3-4.  Solid-state molecular structure of one of the two (AuCl)2P2T3 (80) molecules in the unit cell. Hydrogen atoms and occluded CH2Cl2 are omitted for clarity and thermal ellipsoids are drawn at 50% probability.  67  Table 3-4.  Selected bond lengths and angles for one of the molecules of (AuCl)2P2T3 (80) in the unit cell. Bond Lengths (Å) Au1-Cl1   2.289(3)  Au2-Cl2  2.284(3) Au1-P1 2.232(3) Au2-P2 2.224(3) P1-C3 1.791(10) P2-C10 1.801(10) S1-C1 1.721(13) S1-C4 1.733(10) C1-C2 1.340(16) C2-C3 1.427(14) C3-C4 1.415(15) C4-C5 1.445(14) Angles (º) Cl1-Au1-P1 177.19(11) Cl2-Au2-P2 178.56(16) Au1-P1-C3 112.1(3) Au1-P1-C25 115.6(3) Au1-P1-C31 114.6(4) C3-P1-C25 101.8(5) C1-S1-C4 92.3(5) S1-C1-C2 111.5(8) C1-C2-C3 115.2(11) C2-C3-C4 110.4(9) C3-C4-S1 110.7(7) Torsion Angles (º) S1-C4-C5-S2 -51(1) S2-C8-C9-S3 -49(1)    Exchanging the -Cl group for -CN resulted in small changes in the molecular structure. The torsion angles in (AuCN)2P2T3 changed slightly to 51.6(7)° and 56.3(7)° (Figure 3-5, Table 3-5).  The Au-CN distance was lengthened with respect to that in (AuCN)PPh3; for (AuCN)2P2T3 it was 2.029(8) Å and 2.021(7) Å, whereas for (AuCN)Ph3 it was 2.003(7) Å. 172 All other bond lengths and angles were similar to those in terthiophene115 and (AuCN)PPh3. 172 In addition the distance between the Au and the central thienyl carbons decreased to between 3.26 Å - 3.29 Å.  68  Figure 3-5.  Solid-state molecular structure of (AuCN)2P2T3 (82). Hydrogen atoms and occluded CH2Cl2 are omitted for clarity and thermal ellipsoids are drawn at 50% probability.  Table 3-5.  Selected bond lengths and angles of (AuCN)2P2T3 (82). Bond Lengths (Å) C25-Au1 2.029(8) C38-Au2 2.021(7) P1-Au1 2.2782(16) P2-Au2 2.2741(16) C25-N1 1.108(9) C38-N2 1.103(9) C3-P1 1.815(6) C10-P2 1.805(6) C1-S1 1.702(6) C4-S1 1.737(6) C1-C2 1.361(9) C2-C3 1.412(8) C3-C4 1.377(8) C4-C5 1.455(8) Angles (º) C25-Au1-P1 177.7(2) C38-Au2-P2 174.45(19) N1-C25-Au1 177.7(8) N2-C38-Au2 177.0(7) C3-P1-Au1 111.9(2) C13-P1-Au1 115.7(2) C19-P1-Au1 112.4(2) C10-P2-Au2 113.2(2) C32-P2-Au2 116.7(2) C26-P2-Au2 110.1(2) C1-S1-C4 92.0(3) C2-C1-S1 112.1(5) C1-C2-C3 112.6(6) C4-C3-C2 113.1(6) C3-C4-S1 110.1(4) Torsion Angles (º) S1-C4-C5-S2 51.6(7) S2-C8-C9-S3 56.4(7)   69 Section 3.3.3 – Electronic Absorption Spectra  Despite the lack of aurophilic interactions, all of the Au(I) complexes showed that the presence of the metal influences the conjugation in the phosphino-terthiophene ligand.  The solution absorption spectra of the complexes were obtained (Table 3-6) to probe whether the decreased conjugation observed in the solid-state persisted in solution.  Table 3-6. Electronic absorption maxima of Au(I)-phosphino-oligothiophene complexes. Compound λmax/nm (ε/M -1cm-1) (AuCl)PT3 (76) 238 (22 500), 342 (18 500) (AuSPh)PT3 (77) 342 (14 400) (AuSC6F5)PT3 (78) 345 (14 300) (AuSC6H4OMe)PT3 (79) 344 (15 500) (AuCl)2P2T3 (80) 320 (10 200) {[AuP2T3][NO3]}2·3H2O (81) 360 (6 300) (AuCl)2P2T2 (67) 239 (sh, 35 200) a (AuCl)2P2T4 (68) 252 (28 800), 344 (16 600) a (AuCl)-α-PT3 (83) 263 (11 000), 279 (7 100), 377 (3 200) b (AuCl)2-α-P2T3 (71) 263 (12 000), 267 (12 000), 276 (9 200), 386 (3 900) b Spectra recorded in CH2Cl2 at 296 K. a Absorption data from Ref.88  b Absorption data from Ref.91   The lowest energy band in the absorption spectrum of each of the Au complex is due to the ππ* transitions on the oligothiophene ligand.  Absorption bands for complexes 76 – 79 are at virtually identical wavelengths and are centred near 340 nm.  This is slightly blue-shifted from PT3 in solution, which has a lowest energy absorption band at 354 nm. 173  For comparison, the lowest energy band of P2T4 is at 340 nm, 88 α-PT3 is at 374 nm, and α-PTP is at 389 nm 174 and upon coordination to Au(I) each complex’s absorption maximum shifted by less than 5 nm in solution (Table 3-6).  These previous results suggest that Au(I) has a minimal electronic effect on the oligothiophene when coordinated via an aryl phosphine.  Similarly, the slight blue-shift in the lowest energy ππ* band of (AuCl)PT3, (AuSPh)PT3, (AuSC6F5)PT3 and (AuSC6H4OMe)PT3 is likely indicative of a small electronic effect or small change in conjugation along PT3 from the presence of the Au(I).  70  In contrast, the lowest energy ππ* band of (AuCl)2P2T3 has a dramatic hypsochromic shift of 40 nm from the ππ* band of P2T3 (Figure 3-6).  This is consistent with this being the least conjugated Au complex in the solid-state and with it having reduced conjugation from P2T3.  Figure 3-6.  Absorption spectra of (AuCl)2P2T3 (80) and P2T3 (57) in CH2Cl2 solution.   Given that (AuCl)2P2T3 has the least conjugated terthiophene backbone, it was interesting to determine whether the conjugation of (AuCl)2P2T3 in the solid-state could be disrupted with grinding, as was observed with P2T3.  In addition, this complex was the most easily recrystallized ensuring its purity.  For these reasons, the absorption spectrum of (AuCl)2P2T3 was monitored before and after grinding (Figure 3-7).  71  Figure 3-7.  Solid-state reflectance absorption spectra of microcrystalline (AuCl)2P2T3 (80) before and after grinding.   As in solution, the absorption band of (AuCl)2P2T3 (λmax= 350 nm) is blue-shifted from P2T3 (λmax= 400 nm) in the solid-state.  Grinding the (AuCl)2P2T3 solid resulted in the growth of a shoulder at 400 nm.  Unlike P2T3, the shoulder is red-shifted with respect to microcrystalline (AuCl)2P2T3 and suggests that the P2T3 conjugation in (AuCl)2P2T3 increases upon grinding. In addition, the change in the absorption spectrum of (AuCl)2P2T3 observed with grinding did not change noticeably after 20 minutes.  Section 3.3.4 – Emission Properties of (AuCl)2P2T3 The ease of purification of (AuCl)2P2T3 and the large difference in the lowest energy ππ* absorption between (AuCl)2P2T3 and P2T3 made (AuCl)2P2T3 the most amenable of the Au(I) complexes for study of its emissive properties.  The excitation and emission spectra of (AuCl)2P2T3 are shown in Figure 3-8.   72  Figure 3-8.  Excitation and emission spectra of (AuCl)2P2T3 (80) and P2T3 (57) in CH2Cl2 solution.   The emission maxima from (AuCl)2P2T3 and P2T3 in CH2Cl2 solution are both at 460 nm, which strongly suggests ligand-based emission from (AuCl)2P2T3.  Emission lifetime measurements of (AuCl)2P2T3 (τ = 90 ps (90-95%)) further confirmed emission from a singlet state as the dominant radiative pathway.  In addition, the shift in the excitation band of (AuCl)2P2T3 correlates well with the absorption spectrum and indicates that emission is from (AuCl)2P2T3 and not P2T3 impurities.  Microcrystalline (AuCl)2P2T3 is non-emissive. Upon grinding a microcrystalline powder sample of (AuCl)2P2T3 there was a considerable change in the solid-state emissive properties, as was seen for P2T3.  The non-emissive (AuCl)2P2T3 powder became emissive after grinding (Figure 3-9).  Furthermore, once this emission was induced, it was maintained for at least four days.  The excitation spectrum of ground (AuCl)2P2T3 has a maximum at ~400 nm that coincides with the shoulder in the absorption spectrum of (AuCl)2P2T3 after grinding. The shoulder in (AuCl)2P2T3 corresponds to a red-shift in the absorption band, suggestive of planarization of the terthiophene backbone.  This change in absorption coincides with a change in the solid-state decay pathways such that emission results.  It is unclear whether any change in interaction  73 between the aryl-phosphine groups also occurs upon grinding, which is known to affect solid- state emission in Ag-phosphine systems.123  Figure 3-9.  a) Emission spectrum of (AuCl)2P2T3 (80) before and after grinding. b) Emission and excitation spectra of ground (AuCl)2P2T3 (80).  74 Section 3.3.5 – Powder X-Ray Diffraction Study of (AuCl)2P2T3  The powder X-ray diffraction (PXRD) of (AuCl)2P2T3 was obtained before and after grinding to determine whether any structural changes accompanied the changes in emission and absorption.  Figure 3-10 shows the PXRD of (AuCl)2P2T3 powder before and after grinding. The PXRD confirms that the (AuCl)2P2T3 powder was microcrystalline and the reflections match those generated from analysis of the single crystal structure of (AuCl)2P2T3. Therefore, the (AuCl)2P2T3 in the microcrystalline powder has the same structure as in the single crystal.  Grinding the microcrystalline sample caused the (AuCl)2P2T3 to become amorphous with a broad reflection observed at 2θ = 20° (Figure 3-10).  There was also a broad reflection at 13° with underlying sharp reflections at 9° and 13°, which are coincident with reflections from crystalline (AuCl)2P2T3 and indicate some crystalline (AuCl)2P2T3 is present.  Interestingly, the 1H and 31P{1H} NMR spectra of solutions prepared of the ground sample were identical to those prepared from the microcrystalline sample.  These results indicate that the transformation from microcrystalline to amorphous (AuCl)2P2T3 is not accompanied by a chemical reaction of the material.  Complexes 74 and 75 also both change from microcrystalline to amorphous with grinding that accompanies the change in emissive properties observed.123,139   75  Figure 3-10.  PXRD of (AuCl)2P2T3 (80) a) as prepared, b) ground.    76 Section 3.3.6 – Raman Spectra of (AuCl)2P2T3  Raman spectra of the crystalline and ground (AuCl)2P2T3 were obtained (Figure 3-11) to further probe differences in (AuCl)2P2T3 with grinding.  Both crystalline and ground (AuCl)2P2T3 have strong bands at 1510, 1459 and 998 cm -1, assigned as the asymmetric ν(C=C), symmetric ν(C=C), and ν(C-S) stretches, respectively (Table 3-7).  These stretches are characteristic of oligo- and polythiophenes.175 Significant differences are present between 400 and 800 cm-1 for crystalline and ground (AuCl)2P2T3 samples.  In particular, crystalline (AuCl)2P2T3 has a band at 670 cm -1 that is absent in ground (AuCl)2P2T3.  Previous studies of T3 in solution and the solid-state showed that the ring bending vibration between 650 – 700 cm-1 depends on interannular torsion angles.176  Solid T3 has coplanar rings and only shows a peak at 691 cm-1, but when T3 is in solution with multiple non-planar conformations present there are four peaks between 650 – 700 cm-1.176 Peaks at lower intensity in this region are assigned to the phenyl rings of (AuCl)2P2T3 since they are similar to those observed for (AuCl)PPh3. 177 The decreased intensity of the peak at 670 cm-1 of ground (AuCl)2P2T3 relative to crystalline (AuCl)2P2T3 coincides with the increased planarization of the terthiophene.  Figure 3-11.  Raman spectra of crystalline and ground (AuCl)2P2T3 (80).  77  Table 3-7.  Assignments of Raman bands for (AuCl)2P2T3 (80). Crystalline (AuCl)2P2T3 Ground (AuCl)2P2T3 Bands (cm-1) Assignments Bands (cm-1) Assignments 1586 (w) ν(C=C) (Ph) a 1586 (w) ν(C=C) (Ph) a 1512 (s) νasym(C=C) (Th) b  1509 (s) νasym(C=C) (Th) b 1460 (s) νsym(C=C) (Th) b  1457 (s) νsym(C=C) (Th) b 1400 (br, w) ν(C-C) (Th) b 1400 (br, vw) ν(C-C) (Th) b 1158(w), 1101(w), 1053(w), 1028(w) δ(C-H) b and ν(P-C) a 1157(w), 1100(w), 1056(w), 1028 (w) δ(C-H) b and ν(P-C) a 998 (s) ν(C-S) b and/or ring breathing (ν(C=C) (Ph)) a 998 (s) ν(C-S) b and/or ring breathing (ν(C=C) (Ph)) a 702 (w) Ph vib a 695 (w) Ph vib a 671 (m) Ring bending (Th) c 668 (vw) Ring bending (Th) c 504 (w) Ring deformation a 616 (w) Ring vibrations a   577 (w) Ring vibrations a a Assigned based on Ref. 177  b Assigned based on Ref. 175  c Assigned based on Ref. 176   Section 3.4 – Conclusions  The new complexes (AuSC6F5)PT3 and (AuSC6H4OMe)PT3 were prepared, characterized and compared with previously prepared (AuCl)PT3 and (AuSPh)PT3.  The thiolate had no effect on the torsion angle along the terthiophene backbone or any solution absorption properties.  The bis-phosphino-terthiophene complexes (AuCl)2P2T3 and (AuCN)2P2T3 were synthesized for comparison.  In (AuCl)2P2T3 and (AuCN)2P2T3 the torsion angle along the terthiophene was similar to that in the mono-phosphino-terthiophene counterparts.  Difficulty in purifying (AuCN)2P2T3 prevented its further analysis.  For (AuCl)2P2T3 the solution absorption was significantly hypsochromically shifted with respect to P2T3.  This suggested the reduced conjugation in the solid-state was also present in solution, making it ideal for studying the emissive properties.  (AuCl)2P2T3 had emission consistent with ligand-based fluorescence.  78 Interestingly, microcrystalline powders of (AuCl)2P2T3 were non-emissive, but upon grinding emission similar to the solution emission of the complex appeared.  This was accompanied by a red-shift in the lowest energy ππ* absorption band, which suggests that a planarization of the terthiophene backbone upon grinding.  Furthermore, the Raman spectra suggested changes in the terthiophene backbone could be responsible for the changes observed.  This provides evidence that the Au(I) centre in (AuCl)2P2T3 structurally modifies the terthiophene, which can be changed by grinding.  This differs from other Au(I)-containing tribochromic luminescent complexes in which changes in aurophilic interactions with grinding change the luminescence of the material.  (AuCN)2P2T3 would be more ideal for study as a tribochromic luminescent material since the CN stretch in Au(I)-cyanides is well studied and could be used as a probe to study the changes around the Au-centre, however purification difficulties prevented its further study.   79 CHAPTER 4 GOLD(I) ACETYLIDE COMPLEXES∗  Section 4.1- Introduction   In addition to phosphines that tether Au(I) ions to oligothiophenes,88,91,178 other ligands including thiolates,179 carbenes180 and acetylides181,182 have been used.  Acetylide-Au(I) complexes are particularly interesting since some exhibit relevant properties include NLO behaviour,183 liquid crystallinity184  and excited state reactivity.185,186 The reduced steric bulk of acetylides compared to phosphines could also allow for an aurophilic interaction in the solid- state, which were inhibited by the steric bulk present in the Au(I) complexes with phosphine ligands discussed in Chapter 3.  In addition, it is intriguing to consider whether intramolecular aurophilic interactions are electropolymerizable.  Previous Au(I)-carbene180 and Au(I)-thiolate179 thienyl complexes (84180 and 85,179 Chart 4-1) had free α-positions that allowed them to electropolymerize into Type II and Type III metallopolymers respectively.  These complexes both had intermolecular aurophilic interactions in the solid-state, and films from 84 were stabilized by aurophilic interactions.180 Intramolecular aurophilic interactions, by contrast, have significant effects on conjugation of oligothiophenes as seen in 67 and 68 (Chapter 3) that inhibited their electropolymerization.88  Chart 4-1. Ref.179,180   ∗ Part of this chapter has been published.  Reproduced in part with permission from Kuchison, A. M., Wolf, M. O., Patrick, B. O. (2010) Photophysical Properties and Electropolymerization of Gold Complexes of 3,3''-diethynyl- 2,2':5',2''-terthiophene. Inorg. Chem., 49, 8802-8812 – Copyright 2010 American Chemical Society.  80   Li181 and Vergara92 have studied thienyl-acetylide complexes (Chart 4-2).  Aurophilic interactions were observed for both 86181 and 89.92 Interestingly, for complexes 87 and 88 no aurophilic interactions were observed in the solid-state.181 The α-acetylide complexes also showed an electronic interaction between AuPPh3 and the oligothiophene across the acetylide bridge: the AuPPh3 caused a red-shift in the lowest energy absorption band that depended on whether one or two AuPPh3 groups were coordinated. 181  Chart 4-2. Ref.92,181    Several Au(I)-aryl-acetylide complexes (some examples in Chart 4-3) have long lived emission lifetimes in addition to solid-state aurophilic interactions.185,186 Long lifetimes are desirable for excited state reactivity where electron transfer to an acceptor such as methyl viologen (MV2+, N, N'-dimethyl-4,4'-bipyridium dication) occurs.  For example, complex 90 has an emission lifetime of 1.9 µs in CH3CN and readily reacts with MV 2+.186 Separate studies of terthiophene derivatives187,188 and bis-Au(I) complexes189 show that these species also undergo electron transfer to MV2+.  MV2+ absorbs in the UV region and appears colourless in solution. Upon electron transfer to MV2+, the resulting MV+· has a blue colour with a characteristic band at 600 nm.190 The dramatic colour differences of MV2+ compared to MV+· allows quick assessment of whether electron transfer occurred.  Generated MV+· can react with H+ or H2O to produce H2 in the presence of a catalyst such as Pt (Scheme 4-1).191 Similarly, MV+· can be oxidized at an electrode and thus act as an electron shuttle in a photovoltaic cell.  Therefore, as an electron acceptor, MV2+ has potential applications in H2(g) production and photovoltaics. 191   81 Chart 4-3. Ref.186    Scheme 4-1. Ref.191    Considering the low steric bulk and interesting properties of Au(I)-acetylides, A2T3 was chosen as a ligand for Au(I) to further study the effect of Au(I) on the electronic properties of the terthiophene.   Three complexes were synthesized using A2T3 as a ligand: (AuPPh3)2A2T3, [n- Bu4N][(AuCN)2A2T3] and Au2dppmA2T3 (Chart 4-4).  How the peripheral ligands on Au2A2T3 affect the absorption, luminescence, aurophilic and electrochemical properties was of interest.  In addition, whether (AuPPh3)2A2T3, [n-Bu4N]2[(AuCN)2A2T3] and Au2dppmA2T3 share the excited state properties of other aromatic-Au(I)-acetylide complexes and can transfer electrons to MV2+ was worth investigating.   82 Chart 4-4.   Section 4.2 – Experimental  Section 4.2.1 – General AuCl(tht)154  and methyl viologen hexafluorophosphate192 (MV2+) were prepared according to slightly modified literature procedures. Au(PPh3)Cl was prepared by addition of triphenylphosphine to AuCl(tht).193 [n-Bu4N][CN], triphenylphosphine (PPh3), bis(diphenylphosphino)methane (dppm), and methyl viologen (MV2+) chloride were purchased from Sigma-Aldrich, HAuCl4 was purchased from Strem Chemicals, [n-Bu4N][PF6] was purchased from Fluka Chemicals, and trimethylsilylacetylene was purchased from Acros Chemicals. 1H and 31P{1H} NMR spectra were collected on either a Bruker AV-300 spectrometer or Bruker AV-400 spectrometer.  1H NMR spectra were referenced to residual solvent and 31P{1H} NMR spectra referenced to external 85% H3PO4.  Infrared spectra were obtained on a Nicolet 6700 FTIR with a Smart Orbit™ accessory. Solution and solid-state UV-vis absorption spectra were obtained on a Varian Cary 5000 UV-vis-near-IR spectrophotometer.  Solution excitation and emission spectra were obtained on a Photon Technology International QuantaMaster fluorimeter and were uncorrected for lamp intensity.  Low temperature absorption and emission spectra were obtained from 4:1 ethanol/methanol solutions using an Oxford OptistatDN cryostat. The limited solubility of (AuPPh3)2A2T3, Au2(dppm)A2T3, and A2T3 in the alcohol mixture required dissolving them in a small amount of DMF prior to addition to the ethanol/methanol. Quantum yields were measured using a Labsphere general purpose integrating sphere. Fluorescence lifetime measurements were carried out on a Princeton Instruments Spectra Pro 2300i Imaging Triple Grating Monochromator/Spectrograph with a Hamamatsu Dynamic Range  83 Streak Camera (excitation source: EKSPLA Nd:YAG laser, λ = 355 nm).  Samples were prepared with an optical density of 0.1 at the maximum of the lowest energy absorption band. Cyclic voltammetry was carried out using an Autolab potentiostat.  Either a platinum disk or indium tin oxide (ITO) on a glass slide was used as the working electrode.  The reference electrode was a silver wire and the counter electrode was platinum mesh.  Decamethylferrocene was used as an internal reference to correct the potentials to the saturated calomel electrode (SCE).  The electrolyte, [n-Bu4N][PF6], was recrystallized three times from ethanol and heated to 90°C under vacuum for three days prior to use.  Cyclic voltammetry was carried out in CH2Cl2 dried over an activated alumina column.  Solutions contained 0.1 M [n-Bu4N][PF6] and 1 × 10 -3 M of the appropriate compound.  Lamp intensity powers were measured with an Ophir power meter thermal sensor. Synthesis.  Caution: Although no explosions were encountered here, Au acetylide complexes have previously been shown to be explosive184,194,195 and care must be exercised when working with them.  Section 4.2.2 – Procedures (AuPPh3)2A2T3 (93). NEt3 (3 mL) was added to a stirring CHCl3 solution (50 ml) of AuCl(PPh3) (245 mg, 0.495 mmol) and A2T3 (73 mg, 0.25 mmol).  The solution was left stirring at room temperature for 48 hours.  The CHCl3 was then removed in vacuo and the residue was washed several times with 5 mL aliquots of water.  The residue was washed with acetone and subsequently dissolved in minimal CHCl3 and hexanes was added.  The solution was cooled to 4 o C and a yellow crystalline precipitate formed.  The precipitate was vacuum filtered. Yield: 267 mg, 89%. Crystals suitable for X-ray diffraction were grown from CHCl3/hexanes solution. 1H NMR (400 MHz, CDCl3): δ 7.67 (s, 2H), 7.56 (m, 10H), 7.40 (m, 20H), 7.02 (d, 2H, J = 5.1 Hz), 6.98 (d, 2H, J = 5.1 Hz).  31P{1H} NMR (121 MHz, CDCl3): δ 42.0 (s).  MALDI-TOF-MS m/z 1212 ([M]+).  Anal. Calcd for C52H36Au2P2S3·CHCl3: C, 47.78; H, 2.79.  Found: C, 47.93; H, 2.89.  IR 2226 cm-1 (ν(C≡C)).   84 [n-Bu4N]2[(AuCN)2A2T3] (94). A CH2Cl2 solution  (10 ml) containing (AuPPh3)2A2T3 (100 mg, 0.0824 mmol) and n- Bu4NCN (46.4 mg, 0.173 mmol) was sonicated at room temperature for 9 minutes. Immediately, hexanes (20 ml) were added and the solution sonicated for another 9 minutes during which time a precipitate formed.  The mixture was left undisturbed for one hour and the hexanes/CH2Cl2 solution was then decanted from the solid residue.  The residue was rinsed twice with hexanes (5 mL), then dissolved in 5 mL of a 1:1 mixture of acetone and diethyl ether.  The acetone/ether solution was left at 4o C overnight, during which time bright yellow crystals of [n- Bu4N]2[(AuCN)2A2T3] formed and were collected by vacuum filtration.  Yield: 60 mg, 59%. The crystals were suitable for X-ray diffraction.   1H NMR (400 MHz, CDCl3): δ 7.95 (s, 2H), 7.00 (s, 4H), 3.18 (t, 16 H, J = 8.4 Hz), 1.64 (m, 16 H), 1.43 (m, 16 H), 0.99 (m, 24 H).  Negative ESI-MS m/z 982 (100%, [M-Bu4N] -).  Anal. Calcd for C50H78Au2N4S3: C, 49.01; H, 6.42; N, 4.57.  Found: C, 49.41; H, 6.43; N, 4.91.  IR 2138 cm-1 (ν(C≡N)); 2105 cm-1 (ν(C≡C)).   Au2(dppm)A2T3 (95). A CH2Cl2 (20 mL) solution of (AuPPh3)2A2T3 (121 mg, 0.0998 mmol) and dppm (38 mg, 0.0998 mmol) was sonicated at room temperature for 30 minutes.  Immediately, hexanes (20 mL) were added to the solution and sonicated for 9 minutes during which time a solid precipitate formed.  The solid was washed twice with hexanes (20 mL) and the residue dissolved in 5 mL of a 1:0.25:1 CHCl3-CH2Cl2-acetone solution and left to crystallize.  Dark orange crystals of Au2(dppm)A2T3 formed overnight and were washed three times with acetone.  Yield: 51 mg, 48%.  Crystals suitable for single crystal X-ray diffraction were grown from a CHCl3/CH2Cl2/acetone solution. 1H NMR (300 MHz, CDCl3): δ  7.65 (m, 8H), 7.44 (m, 4H), 7.35 (m, 8H), 7.19 (s, 2H), 7.08 (d, 2H, JHH = 5.4 Hz), 7.00 (d, 2H, JHH = 5.4 Hz), 3.68 (t, 2H, JPH = 10.7 Hz).  31P{1H} NMR (121 MHz, CDCl3): δ  32.3 (s).  TOF m/z 1073 ([M] +).  Anal. Calcd for C41H28Au2P2S3·(CH3)2CO: C, 46.73; H, 3.03.  Found: C, 46.64; H, 3.12.  IR 2107 cm -1 (ν(C≡C)).  Photoinduced electron transfer to MV 2+ .  A solution of either methyl viologen chloride or methyl viologen hexafluorophosphate (4 × 10-3 M) was degassed via three freeze-pump-thaw cycles.   Solutions (10-5 M) of the respective Au complexes and A2T3 was prepared and  85 degassed.  Approximately 1.5 mL of the methyl viologen solution and 1.5 mL of the acetylide compound solution were added to a cuvette under N2(g).  An absorption spectrum was collected to ensure no decomposition of any reactants occurred.  This solution was then irradiated with a handheld lamp (λmax= 365 nm, intensity ~0.5 mW) or a white lamp (400 – 800 nm broadband light, intensity ~50 mW) for 15-16 minutes.  After irradiation, the absorption spectrum of the solution was collected again.  Section 4.2.3 – X-Ray Crystallography Suitable crystals of (AuPPh3)2A2T3, [n-Bu4N]2[(AuCN)2A2T3] and Au2dppmA2T3 were obtained.  The crystal structures were obtained and solved by Dr. B. O. Patrick. All crystals were mounted on glass fibers.  All measurements were made on a Bruker X8 APEX II diffractometer with graphite monochromated Mo-Kα radiation. Data were collected and integrated using the Bruker SAINT106 software package. Data were corrected for absorption effects using the multi- scan technique (SADABS196).  The data were corrected for Lorentz and polarization effects.  The structures were solved by direct methods.108 Diagrams were made using ORTEP-3,109 and POV- RAY. 110   (AuPPh3)2A2T3 (93). Data were collected in a series of φ and ω scans in 0.50° oscillations with 20.0-second exposures. The crystal-to-detector distance was 36.00 mm.  The data were collected to a maximum 2θ value of 56.0°.  Of the 32338 reflections that were collected, 5733 were unique (Rint = 0.034); equivalent reflections were merged.  Data were corrected for absorption effects using the multi-scan technique (SADABS),196 with minimum and maximum transmission coefficients of 0.530 and 0.726, respectively.  The material crystallizes with one half-molecule in the asymmetric unit, residing on a two-fold axis of rotation.  All non-hydrogen atoms were refined anisotropically.  All hydrogen atoms were placed in calculated positions but were not refined.  There was unresolvable solvent (CHCl3, CH2Cl2 or hexanes) in the lattice.  As a result the PLATON/SQUEEZE197 program was used to generate a ‘solvent-free’ data set.  The final cycle of full-matrix least-squares refinement on F2 was based on 5733 reflections and 267 variable parameters and converged (largest parameter shift was 0.00 times its esd).  86 [n-Bu4N]2[(AuCN)2A2T3] (94). The data were collected to a maximum 2θ value of 56.2°. Data were collected in a series of φ and ω scans in 0.50° oscillations with 10.0-second exposures. The crystal-to-detector distance was 36.00 mm.  Of the 61962 reflections that were collected, 12644 were unique (Rint = 0.055); equivalent reflections were merged.  Data were corrected for absorption effects using the multi-scan technique (SADABS),196 with minimum and maximum transmission coefficients of 0.204 and 0.501, respectively.  All non-hydrogen atoms were refined anisotropically.  All hydrogen atoms were placed in calculated positions but were not refined.  The material crystallizes with a small amount of disorder in one thiophene along with its C-C-Au-C-N substituent.  The minor disordered fragment was refined using geometric restraints as well as restraints on anisotropic displacement parameters. The final cycle of full-matrix least-squares refinement on F2 was based on 12644 reflections and 571 variable parameters.  Au2(dppm)A2T3  (95). The data were collected to a maximum 2θ value of 56.2°. Data were collected in a series of φ and ω scans in 0.50° oscillations with 5.0-second exposures. The crystal-to-detector distance was 40.00 mm.  Of the 57624 reflections that were collected, 9505 were unique (Rint = 0.053); equivalent reflections were merged.  The minimum and maximum transmission coefficients were 0.190 and 0.537, respectively.  All non-hydrogen atoms were refined anisotropically.  All C-H hydrogen atoms were placed in calculated positions but were not refined.  The final cycle of full- matrix least-squares refinement on F2 was based on 9505 reflections and 469 variable parameters and converged (largest parameter shift was 0.00 times its esd) with unweighted and weighted agreement factors.   87 Section 4.3 – Results and Discussion  Section 4.3.1 – Synthesis and Design Previously, our group has prepared Au(I) complexes where the metal centres were tethered via β-phosphine substituents on adjacent thiophenes (Chapter 3, Chart 3-1) and these complexes exhibited intramolecular Au-Au interactions.88 However, the combination of the steric bulk of the diphenylphosphine groups and the poor conjugation between adjacent thiophenes in these complexes prevented electropolymerization.88 Addition of a third thiophene ring between terminal phosphine-bearing thiophenes in (AuCl)2P2T3, as discussed in Chapter 3, resulted in improved conjugation along the oligothiophene, but no aurophilic interactions were observed due to the steric bulk of the phosphines.178 To reduce the steric effects, acetylenes were selected to replace the diarylphosphines and a terthiophene was selected to allow planarization of the conjugated backbone. Three Au(I) complexes were synthesized (Chart 4-4) to examine steric, bridging, and aurophilic effects.  Reaction of A2T3 with PPh3AuCl in the presence of base, resulted in the formation of the digold complex, (AuPPh3)2A2T3. This synthesis is similar to that used for several PPh3Au-acetylides. 198,199  To decrease the steric bulk around the Au, the PPh3 ligands in (AuPPh3)2A2T3 can be displaced with the less sterically demanding cyanide ligands to give [n- Bu4N]2[(AuCN)2A2T3].  [n-Bu4N]2[(AuCN)2A2T3] was synthesized by addition of 2.1 equivalents of [n-Bu4N][CN] to (AuPPh3)2A2T3. Finally, bis(diphenylphosphino)methane (dppm) can be used to bridge the two Au(I) centres.  This was accomplished by reaction of (AuPPh3)2A2T3 with stoichiometric equivalents of dppm to form Au2(dppm)A2T3 (Scheme 4-2).   88 Scheme 4-2.   Section 4.3.2 – Solid-State Molecular Structures Crystals suitable for X-ray diffraction of all the gold-acetylide complexes were grown from the appropriate solvents.  The structures show the effects the peripheral ligand has on the Au2A2T3 moiety. Crystals of (AuPPh3)2A2T3 were grown from a CHCl3/hexanes solution. Its solid-state molecular structure is shown in Figure 4-1.  The steric bulk of the AuPPh3 group increases the distortion from planarity of the terthienyl backbone (interannular torsion angle: 159.52(15)° (Table 4-1) in (AuPPh3)2A2T3 relative to A2T3.  In the related complex, (AuPPh3)2(α-A2T3) (88), the metal places less steric demand on the planarity of the terthiophene backbone as evidenced by the small torsion angles (8.7° and 5.0°) in the terthiophene group.181 Although both Au atoms are on the same side of A2T3 in (AuPPh3)2A2T3, the steric bulk of the PPh3 groups prevents an aurophilic interaction.  The Au-Au distance is more than 4.5 Å, greater than the sum of the van der Waals radii (~3.6 Å200).  89  Figure 4-1.  Solid-state molecular structure of (AuPPh3)2A2T3 (93).  Hydrogens have been omitted for clarity and thermal ellipsoids are drawn at 50% probability.  Table 4-1.  Selected bond lengths and angles of (AuPPh3)2A2T3 (93). Bond lengths (Å) C1-C2 1.348(4) C1-S1 1.708(3) C2-C3 1.430(4) C3-C4 1.388(4) C3-C7 1.431(4) C7-C8 1.201(4) C8-Au1 1.995(3) P1-Au1 2.2715(7) Angles (°) C2-C1-S1 112.9(2) C1-C2-C3 112.4(3) C4-C3-C2 112.4(2) C3-C4-S1 110.30(19) C8-C7-C3 178.2(3) C7-C8-Au1 176.5(3) C8-Au1-P1 177.99(8) Torsion angles (o) S1-C4-C5-S2 -159.52(15)  Crystals of [n-Bu4N]2[(AuCN)2A2T3] were grown from an acetone/diethyl ether solution. The solid-state molecular structure of [n-Bu4N]2[(AuCN)2A2T3] is shown in Figure 4-2.  The bond lengths and angles are similar to those in related acetylide and cyano species.181,201 Despite  90 the decreased steric bulk in [n-Bu4N]2[(AuCN)2A2T3], no aurophilic interactions are observed with the shortest distance between Au centres being 7.5 Å.  This is surprising, given that Au(I)- Au(I) interactions are often observed in cationic and anionic Au(I) complexes with low steric bulk around the Au centres.136 The syn orientation of the thiophene rings in the terthiophene backbone of [n-Bu4N]2[(AuCN)2A2T3] prevents the Au centres from approaching one another. This is unlike the anti conformation observed in both A2T3 and (AuPPh3)2A2T3.  In addition, a [n-Bu4N] + counterion is intercalated between adjacent Au atoms in the [(AuCN)2A2T3] 2- unit. The planarity of the terthiophene backbone in the solid-state of [n-Bu4N]2[(AuCN)2A2T3] is similar to (AuPPh3)2A2T3, as evident from the internannular torsion angles of 19.0(4)° and 20.4(5)° in  [n-Bu4N]2[(AuCN)2A2T3] (Table 4-2).  Figure 4-2.  Solid-state molecular structure of [n-Bu4N]2[(AuCN)2A2T3] (94).  Hydrogens have been omitted for clarity and thermal ellipsoids are drawn at 50% probability.  91  Table 4-2.  Selected bond lengths and angles of [(AuCN)2A2T3][n-Bu4N]2 (94). Bond lengths (Å) S1-C1 1.7036(12) S1-C4 1.736(4) C4-C3 1.378(5) C3-C2 1.425(6) C3-C2 1.425(6) C3-C13 1.426(4) C2-C1 1.350(5) C13-C14 1.197(5) C14-Au1 1.984(5) Angles (°) C1-S1-C4 91.9(2) C3-C4-S1 110.8(3) C4-C3-C13 124.3(3) C4-C3-C2 111.7(4) C1-C2-C3 113.5(4) C2-C1-S1 112.1(3) C14-C13-C3 178.0(4) C13-C14-Au1 177.0(3) C14-Au1-C15 178.49(15) N1-C15-Au1  178.0(4) Torsion Angles (°) S1 C4 C5 S2  -19.0(4) S2 C8 C9 S3  20.4(5)   Crystals of Au2(dppm)A2T3 were grown from a CHCl3/CH2Cl2/acetone solution, and its structure is shown in Figure 4-1.  Here, the dppm bridge forces the two Au centres into close proximity and results in an aurophilic interaction200 with a Au1-Au2 distance of 3.1969(2) Å. The small bite angle of the dppm causes the Au-acetylide groups to deviate from linearity (C-C- Au = 167.5(3)° and 174.3(4)° Table 4-3).  In contrast, (AuPPh3)2A2T3 has a C-C-Au angle of 176.5(3)° and [n-Bu4N]2[(AuCN)2A2T3] has C-C-Au angles of 177.0(3)° and 174.9(4)° (note: C(16B)-C(17B)-Au(2B) is 169(8)°). Of the three Au complexes, Au2(dppm)A2T3 has the most planar terthiophene backbone with interannular torsion angles of 176.2(2)° and 178.6(2)°.  In addition, the torsion angle of Au2(dppm)A2T3 is smaller than for A2T3 (Table 2-2, Chapter 2). As in (AuPPh3)2A2T3 and A2T3, all of the S atoms in Au2(dppm)A2T3 are anti to each other.  This conformation minimizes the distance between Au centers, which allows for the Au-Au interaction in Au2(dppm)A2T3.  In contrast, previous gold-oligothiophene complexes with intramolecular aurophilic interactions, 67 and 68 (Chart 3-1), have torsion angles of ~100° between adjacent rings and Au-Au distances of 3.0879(7) and 3.3322(4) Å respectively.88  92   Figure 4-3.  Solid-state molecular structure of Au2(dppm)A2T3 (95).  Hydrogens and occluded acetone have been omitted for clarity and thermal ellipsoids are drawn at 50% probability.   Table 4-3.  Selected bond lengths and angles of Au2(dppm)A2T3 (95). Bond lengths (Å) C1-S1 1.715(4) C4-S1 1.728(4) C1-C2 1.351(6) C2-C3 1.428(5) C3-C4 1.382(5) C13-C14 1.206(5) C15-C16 1.216(5) P1-Au1 2.2648(10) P2-Au2 2.2801(10) Au1-Au2 3.1969(2) Angles (°) C1-S1-C4 92.6(2) C2-C1-S1 111.2(3) C1-C2-C3 113.7(4) C4-C3-C2 112.0(4) C3-C4-S1 110.5(3) C14-C13-C3 176.1(4) C13-C14-Au1 167.5(3) C16-C15-C10 175.7(4) C15-C16-Au2 174.3(4) Torsion Angles (°) S1-C4-C5-S2  -176.2(2) S2-C8-C9-S3 -178.6(2)  93 Section 4.3.3 – Electronic Absorption Spectra The UV/vis absorption spectra of (AuPPh)3A2T3, [n-Bu4N]2[(AuCN)2A2T3], and Au2(dppm)A2T3 (Figure 4-4, Table 4-4), like A2T3 (Chapter 2), are dominated by strong π→π ∗ transitions.  Coordination of the Au centres to the acetylene results in small shifts of the highest energy π→π∗ transition, as has been previously observed for other Au(I)-acetylide complexes.185 This is most clearly evident in [n-Bu4N]2[(AuCN)2A2T3] where λmax = 260 nm.  In (AuPPh3)2A2T3 and Au2(dppm)A2T3, the higher energy transitions have A2T3 ππ * transitions and additional contributions from the π→π∗ transitions of the phenyl rings of PPh3 and dppm. The lower energy bands in the gold complexes are all red-shifted with respect to the lower energy band in A2T3, as previously observed in related Au(I)-acetylide complexes (Chart 4-2). 181 As mentioned, the red-shift has been attributed to electronic interactions of the acetylide ligand with AuPPh3. 181 By contrast, the compounds discussed here demonstrate that changing the peripheral ligands on Au2A2T3 changes the electronic interaction of the Au with the A2T3.  The larger bathochromic shift of Au2dppmA2T3 is a result of the increased conjugation along the terthiophene backbone imposed by the molecular geometry as well as electronic effects due to the dppm ligand. Additional bands between 300-315 nm in the spectra of Au2(dppm)A2T3, (AuPPh3)2A2T3, and [n-Bu4N]2[(AuCN)2A2T3] may be due to MLCT transitions.  Several other gold acetylide complexes, such as those included in Chart 4-3, have bands with contributions from MLCT transitions in this region.185,186,202,203  94  Figure 4-4.  Electronic absorption spectra of (AuPPh3)2A2T3 (93), [n-Bu4N]2[(AuCN)2A2T3] (94), and Au2(dppm)A2T3 (95) at 298 K in CH2Cl2.  Low temperature UV/vis spectra of the molecules in EtOH/MeOH glasses were obtained in order to gain further insight into their electronic behaviour. In an EtOH/MeOH (4:1) solution at room temperature, the absorption spectra of all the compounds are similar to those obtained in CH2Cl2.  In a frozen EtOH/MeOH glass at 85 K, increased vibronic coupling is observed for all the compounds (Figure 4-5, Figure 4-6).  The lowest energy electronic transition for all the compounds, observed as a single broad band at room temperature, separates into several bands at 85 K with ~1400-1490 cm-1 spacing.  This vibronic coupling is attributed to thiophene ring vibrations120 and C-C stretches121 as was present in A2T3.  Low temperature studies on T3 show similar vibronic structure.118,119 In [n-Bu4N]2[(AuCN)2A2T3], like A2T3, there appear to be additional sharp bands in the lower energy region of the spectrum.  These may be due to C-H vibronic coupling or the presence of multiple structural conformations frozen out at low temperature.  The higher energy transitions also show vibronic coupling with the thienyl rings, consistent with an electronically delocalized system. The spectra of all the complexes, like A2T3, exhibit a bathochromic shift in the lowest energy band with decreasing temperature.  As discussed in Chapter 2, the absorption of A2T3  95 red-shifts by ~900 cm-1 upon cooling to 85 K and this is likely a result of increased planarity and therefore increased conjugation of the molecule at low temperature as occurs with T3 upon cooling to 77 K.118 At low temperature, the spectra of the Au(I) complexes are considerably less red-shifted than the spectrum of A2T3.   At 85 K the lowest energy absorption bands are bathochromically shifted by ~480 cm-1, ~450 cm-1 and ~360 cm-1 for [n-Bu4N]2[(AuCN)2A2T3], Au2(dppm)A2T3 and (AuPPh3)2A2T3 respectively. This suggests that the presence of the Au(I) centres restrict rotation of the thienyl units more than in free A2T3 that is not hindered by the metal centres.  Table 4-4.  Absorption data for compounds at 298 K in CH2Cl2 solutions and 85 K in MeOH/EtOH. Compound λmax /nm (εmax/M -1cm-1) at 298 K λmax/nm at 85 Κ A2T3 (59) 274 (9 000), 385 (21 000) 271 (sh), 280, 295, 308, 379, 393 (sh), 401, 419 (sh), 427 (AuPPh3)2A2T3 (93) 267 (34 000), 307 (24 000), 411 (24 000) 262, 303, 323 (sh), 390, 412, 438 [n-Bu4N]2[(AuCN)2A2T3] (94) 260 (25 000), 320 (18 000), 404 (25 000) 259, 310, 322, 393, 409, 414, 435, 441 (sh) Au2(dppm)A2T3 (95) 301 (33 000), 326 (28 000), 421 (15 000) 268, 275, 289, 312, 326, 400, 425, 454 (AuPPh3)α-A2T3 (88) 401 (sh, 55 000), 421 (60 000), 451 (sh, 35 000)a - a At 293 K, from Ref.181    96  Figure 4-5.  Electronic absorption spectra of a) (AuPPh3)2A2T3 (93), b) [n- Bu4N]2[(AuCN)2A2T3] (94) at 298 K and 85 K.  97  Figure 4-6.  Electronic absorption spectrum of Au2(dppm)A2T3 (95) in EtOH/MeOH (4:1) at 298 K and 85 K.  Section 4.3.4 – Emission Spectra   (AuPPh3)2A2T3 and [n-Bu4N]2[(AuCN)2A2T3] are emissive at room temperature and their excitation and emission spectra in CH2Cl2 solutions are shown in Figure 4-7.  The excitation spectra of the molecules match their respective electronic absorption spectra, except <300 nm where the low intensity of the xenon lamp results in weak emission.  The emission bands of (AuPPh3)2A2T3 and [n-Bu4N]2[(AuCN)2A2T3] are red-shifted with respect to those of A2T3 (Figure 4-7, Table 4-5), but have similar vibronic coupling characteristic of A2T3 (Chapter 2). The presence of the Au atoms did not affect the excited state lifetime of the compounds, which are emissive at room temperature and had excited state lifetimes of <50 ps that is similar to A2T3 in CH2Cl2 solution.  These short lifetimes are typical of fluorescence of terthiophene derivatives. For example, emission lifetimes of phosphonic acid monoethyl ester and carboxylic acid derivatized terthiophenes are ~20 and 200 ps, respectively.204,205  The small Stokes shift, similar band shape of the emission to that of A2T3, and short emission lifetimes of the Au complexes are consistent with ligand-based emission from a singlet state.  98   Figure 4-7.  Fluorescence emission and excitation spectra of (AuPPh3)2A2T3 (93) and [n-Bu4N]2 [(AuCN)2A2T3] (94).  Unlike (AuPPh3)2A2T3 and [n-Bu4N]2[(AuCN)2A2T3], Au2(dppm)A2T3 is non-emissive at room temperature.  This suggests that either radiationless decay dominates the relaxation of the excited state or any emission is too weak to be observed.  There are several Au(I) complexes known where ligand phosphorescence is the dominant emission observed in solution,186,206,207 such as 90 – 92 in Chart 4-3,186 and it is possible that this also occurs in Au2(dppm)A2T3.   Since the terthienyl group in Au2(dppm)A2T3 is remarkably planar, the ligand-based triplet state may be populated more readily than in [n-Bu4N]2[(AuCN)2A2T3] or (AuPPh3)2A2T3.  Sparging a solution of Au2(dppm)A2T3 with nitrogen gas did not result in any observable emission. Phosphorescence from T3 is difficult to observe, but has been reported at 826 nm at 18 K 208 and at 682 nm at 80 K using nanosecond excitation with gated detection.209 Such experimental difficulties may complicate the observation of a thiophene-based triplet emission from Au2(dppm)A2T3. Alternatively, radiationless decay due to Au(I)-Au(I) states may occur.  Gold- based emission is sensitive to the ligands present and these can result in non-emissive interactions.210  99 Interestingly, Au2(dppm)A2T3 is emissive at low temperature.  The emission bands are red-shifted with respect to those seen in the other compounds (Table 4-5).  As in (AuPPh3)2A2T3 and [n-Bu4N]2[(AuCN)2A2T3], the small Stokes shift between the excitation and emission bands of Au2(dppm)A2T3 is consistent with ligand-based emission. The strong emission from Au2(dppm)A2T3 at 85 K decreases with increasing temperature and is essentially gone >185 K (Figure 4-8).  A Jablonski energy diagram of the postulated states in Au2(dppm)A2T3 is shown in Figure 4-9.   Figure 4-8.  Variable temperature emission (λex = 427 nm) and excitation spectra (λem = 496 nm) of Au2(dppm)A2T3 (95).   100  Figure 4-9.  Schematic Jablonski diagram for Au2(dppm)A2T3.  As observed in the absorption spectra, the low temperature emission spectra show vibronic coupling with the thiophene ring vibrations (Figure 4-10 and Table 4-5).  The 85 K emission spectra for (AuPPh3)2A2T3, [n-Bu4N]2[(AuCN)2A2T3] and Au2(dppm)A2T3 all have four bands separated by ~1400 cm-1, similar to A2T3 (Chapter 2).  The low energy region of the excitation spectra match the respective absorption spectra at low temperature in all cases.  Unlike the absorption spectra, the emission bands do not shift with decreasing temperature.  This indicates that fluorescence is likely occurring from a state localized on the planar oligothiophene backbone as has previously been observed in T3 118 and A2T3.   The intensity of the emission also increased with decreasing temperature, consistent with reduced nonradiative decay pathways at low temperature.  Table 4-5.  Emission data for compounds at 298 K in CH2Cl2 and 85 K in MeOH/EtOH. Compound λem/nm at 298 K λem/nm at 85 K A2T3 (59) 438, 462 432, 461, 493, 529 (AuPPh3)2A2T3 (93) 452, 479 451, 482, 517, 559 [n-Bu4N]2[(AuCN)2A2T3] (94) 447, 475 448, 478, 511, 553 Au2(dppm)A2T3 (95) - 465, 498, 536, 581 (AuPPh3)2α-A2T3 (88) 472, 499, 545 a - aAt 293 K, from Ref.181  101  Figure 4-10.  Emission and excitation of a) (AuPPh3)2A2T3 (93) and b) [n-Bu4N]2 [(AuCN)2A2T3] (94) at 298K and 85 K in EtOH/MeOH.   102 Section 4.3.5 – Excited State Reactivity with Methyl Viologen The excited state oxidation potentials (E(M+/M*)) of (AuPPh3)2A2T3, [n- Bu4N]2[(AuCN)2A2T3] and Au2(dppm)A2T3 were calculated using Equation 4-1 where E(M/M +) is the first electrochemical oxidation potential and E* is the emission energy.211 The calculated excited state redox potentials are shown in Table 4-6.  Equation 4-1. Ref.211 ** )/()/( EMMEMME −= ++  Table 4-6.  Calculated excited state redox potentials of compounds. Compound E(M+/M*) (V vs. SCE) A2T3 (59) -1.77 (AuPPh3)2A2T3 (93) -1.40 [n-Bu4N]2[(AuCN)2A2T3] (94) -1.84 Au2(dppm)A2T3 (95) -1.90  Given that the reduction potential of  (MV2+/ MV+·) is –0.69 V vs. SCE,212  it is predicted from Equation 4-2211 (where E0(M+/M*) is the standard excited state oxidation potential of a compound and E0(MV2+/ MV+·) is the standard reduction potential of MV 2+)  that the singlet states of A2T3 and all of the gold complexes are thermodynamically capable of photo-reducing MV 2+.  Equation 4-2.  Ref.211 )/()/( 20*00 •+++ −=∆ MVMVEMMEG  Irradiation of CH3CN solutions of A2T3 and MV 2+ with white or UV light results in a substantial decrease in the intensity of the A2T3 absorption band at 385 nm (Figure 4-11). The characteristic blue colour of the MV+· radical cation was not observed after this irradiation. Irradiation of A2T3 in the absence of MV 2+ under the same conditions did not result in a decrease in the absorption band intensity.  These results suggest some interaction between A2T3 and MV 2+  103 occurs upon irradiation, possibly resulting in decomposition of the A2T3, however there is no evidence for photoinduced electron transfer. As with A2T3, none of the gold compounds show significant decomposition with light irradiation in CH3CN.  However, a shoulder appears at 470 nm in the absorbance spectrum of [n- Bu4N]2[(AuCN)2A2T3] when left in solution overnight.  Since this suggests possible decomposition, solutions of [n-Bu4N]2[(AuCN)2A2T3] were used immediately after preparation. By contrast, the spectra of (AuPPh3)2A2T3 or Au2(dppm)A2T3 remained stable when solutions were left overnight. Irradiation of (AuPPh3)2A2T3/MV 2+ solutions with either UV or white light resulted in the appearance of absorption bands due to MV+· (Figure 4-12).190 The short emission lifetime for this complex suggests that either intermolecular electron transfer from the singlet state is extremely rapid, or another, nonemissive, excited state is involved in the electron transfer. Although the above calculations suggest excited [n-Bu4N]2[(AuCN)2A2T3] as thermodynamically a stronger reducing agent than (AuPPh3)2A2T3,  UV and white light irradiation resulted in no absorption indicating the presence of MV+·.  It is possible that there is a large activation barrier for electron transfer, or that [(AuCN)2A2T3] 2- and MV2+  form an ion-pair in solution causing back-electron transfer to be rapid.  [Au(CN)2] - has been prepared with a MV2+  counterion, 213 however there are no literature reports of electron transfer from [Au(CN)2] - to MV2+ to yield MV+·. Substituting PPh3 for dppm results in different excited state properties. Photo-excitation of a CH3CN solution of Au2(dppm)A2T3/MV 2+ solution with UV light resulted in the observation of MV+· (Figure 4-13), but white light did not.  Therefore, population of higher energy states must be needed for electron transfer. The difference between (AuPPh3)2A2T3 and Au2(dppm)A2T3 may be related to the rigidity or aurophilic interaction in the latter.    104  Figure 4-11.  Acetonitrile solutions of A2T3 (59) and MV 2+ irradiated with a) 365 nm light and b) broadband white light.    105  Figure 4-12.  Acetonitrile solutions of (AuPPh3)2A2T3 (93) and MV 2+ irradiated with a) 365 nm light and b) broadband white light.    106   Figure 4-13.  Acetonitrile solutions of Au2(dppm)A2T3 (95) and MV 2+ irradiated with 365 nm light.  Section 4.3.6 – Cyclic Voltammetry and Electropolymerization  Oligothiophene complexes may be electropolymerized, giving materials with longer conjugation lengths. As mentioned, previous attempts to electropolymerize complexes with intramolecular Au-Au (67 and 68 (Chapter 3)88) interactions were unsuccessful. The structures of (AuPPh3)2A2T3, [n-Bu4N]2[(AuCN)2A2T3] and Au2(dppm)A2T3 indicate they all have relatively planar terthiophene ligands and thus are good candidates for electropolymerization. The oxidative electropolymerization reaction of the Au complexes, and the proposed structure of the products are shown in Scheme 4-3.   107 Scheme 4-3.   Cyclic voltammetry of (AuPPh3)A2T3 shows one irreversible oxidation wave at 1.16 V vs SCE.  Repeated scans resulted in increased current with each subsequent oxidation wave (Figure 4-14), thus showing evidence that electropolymerization is occurring.  As the number of scans is increased, the oxidation wave also shifted to higher potential.  This shift suggests that either the conjugation in the electropolymerized material is less than in the monomer, or that a poorly conductive material forms as a consequence of the electropolymerization.  With two large AuPPh3 groups close together, steric interactions may cause twisting along the oligo/polythiophene backbone.  Lardiés also observed an increase in oxidation potential with increasing scans during electropolymerization.179 XPS analysis of the films prepared here revealed a lower Au content than would be expected from the monomer formula, despite analytically pure monomer being used (Table 4-7).  Metal-acetylide bonds are polar,184 and it is possible that oxidative electropolymerization decreases the electron density at the acetylide thereby weakening the polar character of the Au-C bond, allowing [AuPPh3] + to dissociate from the polymer.  A reduction wave is observed at 0.5 V.  Waves at similar potentials are observed for Au nanoparticles and are attributed to reduction of Au oxide.214 It is possible that Au(0) particles are formed by loss and reduction of Au from the polymer.  Alternatively, this could indicate poly-A2T3 formation since a similar reduction wave is observed during electropolymerization of A2T3 (Chapter 2, Figure 2-11). The presence of this wave with repetitive scanning may indicate loss of Au from the polymer is occurring.  108  Figure 4-14.  Electropolymerization of (AuPPh3)2A2T3 (93) on an ITO electrode (scan rate = 100 mV/s).  Solvent = CH2Cl2.  Electrolyte = 0.1 M [n-Bu4N][PF6].   [n-Bu4N]2[(AuCN)2A2T3] also has one irreversible oxidation wave at 1.08 V vs SCE (Figure 4-15).  With increasing scans, the oxidation wave became quasireversible and the current increases, as expected for electropolymerization on the working electrode surface.  XPS data shows the same Au:S elemental composition as the [n-Bu4N]2[(AuCN)2A2T3] monomer supporting the conclusion that the Au-acetylide complex remains intact (Table 4-7).  The lower nitrogen content suggests less counterion may be present in the polymer than in the monomer and could indicate some p-doping of the resulting polythiophene.  Doped polymer would carry a positive charge on the backbone balancing the negative charge at the metal, thus no longer requiring counterions for charge balance.   109  Figure 4-15.  Electropolymerization of [n-Bu4N]2[(AuCN)2A2T3] (94) on a Pt disk electrode (scan rate = 100 mV/s).  Solvent = CH2Cl2.  Electrolyte = 0.1 M [n-Bu4N][PF6].  Similarly, the growth in the oxidation wave of an Au2(dppm)A2T3 solution with increasing scans indicates electropolymerization of this complex (Figure 4-16 (a)).  The CV of Au2(dppm)A2T3 has two oxidation waves, one at 0.76 V and another at 1.51 V vs SCE.  Metal- metal interactions are known to stabilize Au(II) centres.215 For example, [(Au2{µ- (CH2)2PPh2}(µ-dppa)][ClO4] (dppa = Ph2PNHPPh2) has an irreversible oxidation wave at 0.92 V216 while [Au2(µ-CH2PPh2CH2)2] oxidizes at 0.11 V. 203 Repetitive scanning past the first oxidation wave of Au2(dppm)A2T3 resulted in no increase in current, which suggests the oxidation wave at 0.76 V is from a Au(I/II) oxidation process.  Scanning to higher potential resulted in increased conductivity and therefore polymer formation, which suggests the oxidation wave at 1.51 V is from a terthiophene-based oxidation.  A reduction wave, similar to that found in the CV of (AuPPh3)2A2T3, appears at –0.35 V and increases with repetitive scans.  Repetitive scans resulted in a shiny yellow-gold film on the working electrode.  The XPS analysis on the poly-Au2(dppm)A2T3 film indicates slightly less Au than expected from the monomer formula is present, but does not show the same dramatic loss of Au as in poly-(AuPPh3)2A2T3 (Table 4-7). The bridging dppm and the lower steric bulk of this ligand relative to PPh3 may inhibit  110 [Au2dppm] 2+ dissociation during electropolymerization.  Interestingly, a poly-Au2(dppm)A2T3 film in monomer free solution showed a Au(I/II) oxidation wave in addition to the polythiophene oxidation wave as shown in Figure 4-16 (b), which suggests that the Au-Au interaction persists in the polymerized material.  Table 4-7.  XPS analysis data of electropolymerized films. Compound %Au %S %P %N Au:S Au:N Au:P poly-(AuPPh3)2A2T3) 0.27 8.50 - - 1:31 - -  0.51 8.72 0.98 - 1:17 - 1:1.9  0.44 9.68 0.59 - 1:22 - 1:1.3 poly-{[n-Bu4N]2[(AuCN)2A2T3]} 5.50 10.07 - 3.79 1:1.8 1:0.6 - poly-Au2(dppm)A2T3 1.75 6.87 2.67 - 1:3.9 - 1:1.5  2.18 5.81 3.13 - 1:2.6 - 1:1.4  0.77 6.23 0.61 - 1:8.1 - 1:0.8   111  Figure 4-16.  a) Electropolymerization of Au2(dppm)A2T3 on a Pt disk electrode (scan rate = 100 mV/s) and b) CV of poly-Au2(dppm)A2T3 at a Pt disk electrode in monomer-free solution. Electrolyte = 0.1 M [n-Bu4N][PF6].  Solvent = CH2Cl2.   112  The films were further characterized by obtaining their absorption spectra (Figure 4-17). As with A2T3, the electropolymerized Au(I) acetylides had a negligible shift in the absorption maxima compared to their respective monomer absorption bands.  The bands of poly- (AuPPh3)2A2T3, poly-{[n-Bu4N]2[(AuCN)2A2T3]} and poly-Au2(dppm)A2T3 were broader than in (AuPPh3)2A2T3, [n-Bu4N]2[(AuCN)2A2T3] and Au2(dppm)A2T3 respectively, which could be a result of solid-state interactions.   Figure 4-17.  Solid-state absorption spectra of electropolymerized poly-(AuPPh3)2A2T3, poly- {[n-Bu4N]2[(AuCN)2A2T3]} and poly-Au2(dppm)A2T3 on ITO substrate.   Section 4.4 – Conclusions   Three gold(I) acetylide species were synthesized: (AuPPh3)2A2T3, [n- Bu4N][(AuCN)2A2T3] and Au2(dppm)A2T3.  The electronic properties of the gold complexes are explained by the planarity of the oligothiophene backbone and the presence of an aurophilic  113 interaction.  Of the three gold complexes, only Au2(dppm)A2T3 had an aurophilic interaction in the solid-state.  The steric bulk of the PPh3 in (AuPPh3)2A2T3 prevented an aurophilic interaction, while the counterion and orientation of adjacent thiophene rings in the terthiophene backbone in [n-Bu4N]2[(AuCN)2A2T3] prevented an aurophilic interaction.  In addition to allowing Au-Au interactions, the peripheral ligand on the Au2A2T3 unit also influences the electronic absorption spectrum of each of the complexes.  In the case of Au2(dppm)A2T3, the notably more planar A2T3 also caused a significant red-shift with respect to the other complexes. Both (AuPPh3)2A2T3 and [n-Bu4N]2[(AuCN)2A2T3] exhibit ligand-based emission.  At room temperature, this emission is quenched in Au2(dppm)A2T3 presumably because of either the planarity of A2T3 or aurophilic interaction.  At 85 K, Au2(dppm)A2T3 shows ligand-based emission, suggesting that the radiationless transitions are thermally allowed at room temperature for this complex.  The differences in the excited state between the gold complexes were further studied by using MV2+ as an electron acceptor.  (AuPPh3)2A2T3 showed electron transfer to MV2+ upon UV or white light irradiation, while [n-Bu4N]2[(AuCN)2A2T3] did not, and Au2(dppm)A2T3 only showed electron transfer with UV irradiation.  This suggests there are significant differences in the excited states between these complexes.  Finally, the substituents on the Au2A2T3 moiety also influenced the observed electrochemical properties. Despite (AuPPh3)2A2T3 electropolymerizing into a conducting film, the XPS analysis indicated that the polymerized material did not match the monomer formula.  This suggests that the poly- (AuPPh3)2A2T3 is electrochemically unstable and the [AuPPh3] + does not stay bound to the acetylide.  When the negatively charged CN- ligand was used instead in [n- Bu4N]2[(AuCN)2A2T3], the Au ratio indicated that the polymer retained the monomer formula, but some p-doping may have occurred on the polythiophene backbone.  Au2(dppm)A2T3 showed evidence of an aurophilic interaction in solution with an oxidation wave at 0.76 V vs SCE. Furthermore, Au2(dppm)A2T3 electropolymerized and the CV of the polymer suggested that the Au-Au interaction was prevalent in the polymerized material.  This shows that the intramolecular Au-Au interaction is stable during electropolymerization and is present in the resulting material.  Since [n-Bu4N]2[(AuCN)2A2T3] is more stable during electropolymerization than (AuPPh3)2A2T3 or Au2(dppm)A2T3, additional anionic complexes would be worth investigating. In particular, it would be interesting to study whether using anionic bridging ligands such as 1,2- dithiolethane or 2-(diphenylphosphino)-ethanethiol would increase the stability of the aurophilic interaction during electropolymerization.  These systems could have different properties from the complexes studied here.  If the proposed complexes undergo electron transfer with acceptors and  114 successfully electropolymerize, the excited state reactivity of the polymer material with MV2+ and the H2(g) generation ability would be interesting for future studies.  115 CHAPTER 5 RUTHENIUM(II)-PHOSPHINE-OLIGOTHIOPHENE COMPLEXES  Section 5.1 – Introduction  Ru(II) complexes are studied in a range of fields for their anticancer,217 catalytic218 and electronic properties.219  The electronic properties of Ru(II)-polypyridine complexes make them promising for use in clean energy alternatives since their absorption, emission, photochemical reactivity, and electrochemical characteristics are potentially useful in photovoltaic cells.  Grätzel’s group first developed molecular-based photoelectrochemical cells220,221 or dye- sensitized-solar cells (DSSCs).  These fabricated cells function similarly to photosynthesis in plants as a cascade of reactions is involved in both cases.  A DSSC consists of a light absorber, or dye, which upon photo-excitation can inject an excited electron from its LUMO into the conduction band of TiO2 that subsequently injects the electron into the photoanode (often ITO or SnO coated glass).  To regenerate the dye, an electron donor (often I-) donates an electron into the dye’s HOMO and the donor is then reduced at the cathode to complete the circuit (Figure 5-1).  The most efficient DSSCs to date have ~10% efficiency, using N719 dye222 and Black dye223 (Chart 5-1) with an I-/I3 - donor.  Figure 5-1.  Schematic of electron flow in a DSSC adapted from Ref.224   116 Chart 5-1.  Ref.222, 223    Recombination and interception pathways decrease the overall efficiency of a DSSC. Electrons can recombine through either relaxation of D* to D or by electrons donated into the metal-oxide reducing D+, or by interception of the electron by the oxidized reducing agent (often I3 -).  Minimization of these processes is necessary in order to harvest the maximum number of photo-excited electrons for electrical current.  Therefore the photo-excited electrons must be injected into the CB of the metal oxide faster than the electrons decay back to the ground state. The best DSSC system, N719/TiO2 has a quantum yield of injection of ~80% from the triplet state.225 For this system 50% of electrons are injected between 8226 – 200 ps225 and ~ 10% of the electrons take longer than 1 ns to inject.226 Since the excited-state lifetime of N719 is an order of magnitude greater than the injection lifetime of the electron, decay of D* to D is not a competitive decay pathway that leads to loss of photo-excited electrons.  For efficient DSSCs, the excited state lifetimes of the dyes must be long enough for all photo-excited electrons to be injected into the CB of the metal oxide.  The injection time depends on the composition of the DSSC such as the dye, the metal oxide and the electrolyte used.225 In practice, the excited-state lifetime of Ru dyes are not often a limitation in DSSCs, but the electron injection rates are of greater concern since faster electron rates cause electron density to build up at the dye – metal oxide interface that increases the rate of recombination and interception.227  In addition to Ru(II) complexes used in DSSCs, polymer-based DSSCs are another promising area of research.  Plastic solar cells typically use p-type semiconducting polymers, such as PPV or polythiophene derivatives, with PCBM ([6,6]-phenyl-C61-butyric acid methyl acid methyl ester) as an electron acceptor sandwiched between two electrodes.16  These plastic solar cells are projected to reach efficiencies comparable to Ru(II)-polypyridyl based cells.228  Of  117 the polymers used in polymer-based photovoltaics, poly-3-hexylthiophene is considered one of the best p-type organic semiconductors to use.127 Combining the electronic properties of Ru(II) complexes and oligothiophenes is therefore attractive for the development of new dyes for electrochemical cells. Previous studies in our group coupled Ru(II)-bpy derivatives with oligothiophenes in [Ru(2,2'-bpy)2(PT3-P,S)][PF6]2, [Ru(2,2'-bpy)2(PT5-P,S)][PF6]2, [Ru(2,2'-bpy)2(PT3-P,C)][PF6]2 and [Ru(2,2'-bpy)2(PT5-P,C)][PF6]2 (Chart 5-2). 86,94 The coordination mode in these complexes can be reversibly altered from Ru-S to Ru-C bonding with an acid-base reaction.  Interestingly, [Ru(2,2'-bpy)2(PT5-P,C)][PF6]2 had a long lived charge-separated state of 2.2 µs. 229 This long lifetime of the delocalized hole on the oligothiophene allows for sufficient time for the hole to react with appropriate donors in a DSSC and is comparable to the common dye N3 (Chapter 2 (37), N719 fully protonated) that has a lifetime of 50 ns.84  Chart 5-2.  Ref.86,94   Earlier studies with Ru(II) phosphino-oligothiophene complexes, 100-103 (Chart 5-3), showed the thiophene ligand was hemilabile.173  The thiophene in complex 100 was displaced by CO, resulting in complex 101.173 Both cis-Ru(PT3-P,S)(dppm)Cl2 and trans-Ru(PT3- P,S)(dppm)Cl2 also reacted with CO. 173 It is of interest to flank a terthiophene with two phosphines using the P2T3 motif to determine if this improves the stability of Ru(II) phosphino- oligothiophene complexes.  In addition, the effect of charge and conjugation length on the electronic behaviour of the complexes is of interest.  118  Chart 5-3.  Ref.173    To determine the ability of P2T3 to function as a tridentate ligand on Ru(II), a series of neutral complexes (Ru(P2T3)Cl2(DMSO), Ru(P2T3)Cl2(CH3CN), Ru(P2T3)Cl2(4,4'-bpy) and [Ru(P2T3)Cl2(N-Me-4,4'-bpy)][I]) and cationic complexes ([Ru(P2T3)(CH3CN)2Cl][PF6], [Ru(P2T3)(2,2'-bpy)Cl][PF6] and [Ru(P2T3)(tpy)][PF6]2) were synthesized (Chart 5-4).   The effect of the conjugation length of the oligothiophene on the properties of the Ru(II) complexes was probed using the P2T5 ligand by preparing Ru(P2T5)Cl2(DMSO), and [Ru(P2T5)(tpy)][PF6]2 (Chart 5-5).   Since [Ru(P2T3)(2,2'-bpy)Cl][PF6] contains a chelating polypyridine in addition to P2T3, its excited-state properties were also of interest for comparison with dyes used in existing DSSCs.   119 Chart 5-4.   Chart 5-5.    120  Section 5.2 – Experimental  Section 5.2.1 – General Ru(DMSO)4Cl2, 230 Ru(2,2'-bpy)Cl2(DMSO)2, 231 and Ru(tpy)Cl2(DMSO) 232 were prepared according to literature procedures.  Ruthenium(III) chloride hydrate was purchased from Strem.  Acetonitrile was dried over 3 Å sieves.  1H and 31P{1H} NMR spectra were obtained on either a Bruker AV-300 or Bruker AV-400 spectrometer and referenced to residual solvent or external H3PO4.  UV-vis spectra were obtained on a Varian-Cary 5000 UV-vis-near- IR spectrophotometer in HPLC grade CH2Cl2 and acetonitrile.  Infrared spectra were obtained on a Nicolet 6700 FTIR with a Smart OrbitTM accessory.  Low temperature absorption and emission spectra were obtained using an Oxford OptistatDN cryostat with solutions in 4EtOH:1MeOH with minimal DMF (to dissolve Ru(P2T3)Cl2(DMSO), Ru(P2T3)Cl2(CH3CN), Ru(P2T3)Cl2(4,4'- bpy), and [Ru(P2T3)Cl2(N-Me-4,4'-bpy)][I -].  Transient absorption measurements were carried out on a Princeton Instruments Spectra Pro 2300i Imaging Triple Grating Monochromator/Spectrograph with a Hamamatsu Dynamic Range Streak Camera (excitation source: EKSPLA Nd:YAG laser, λ = 355 nm).  Cyclic voltammetry  data were obtained on a on an Autolab potentiostat with either a platinum disk working electrode, silver wire reference electrode, and platinum mesh counter electrode.  Decamethylferrocene was used to correct the potentials to saturated calomel electrode (SCE).  The electrolyte was [n-Bu4N][PF6], which was recrystallized three times from ethanol and heated to 90°C under vacuum for three days prior to use.  Section 5.2.2 – Procedures Ru(P2T3)Cl2(DMSO) (104). Ru(DMSO)4Cl2 (78.6 mg, 0.162 mmol) and P2T3 (100 mg, 0.162 mmol) were added to degassed toluene (3 mL).  The yellow slurry was heated to reflux for two hours, during which time it gradually became red and an orange precipitate formed.  The solution was cooled to room temperature and the orange precipitate was vacuum filtered.  Yield: 93 mg, 64%.  1H NMR (300 MHz, CDCl3) δ 8.07 (m, 4H), 7.69 (m, 4H), 7.44 (s, 2H), 6.96 (d, 2H, J = 5.4 Hz), 1.79 (s, 6H).  121 31P{1H} NMR (121 MHz, CDCl3) δ 1.5 (s).  Anal. Calcd for (C38H32Cl2OP2RuS4)·2(H2O): C, 50.55; H, 4.02.  Found: C, 50.46; H, 4.06. IR 1007.0 cm-1 (ν(S=O)).  Ru(P2T3)Cl2(CH3CN) (105). A slurry of Ru(DMSO)4Cl2 (393 mg, 0.811 mmol) and P2T3 (500 mg, 0.811 mmol) in toluene (15 mL) was heated to reflux.  Gradually, the two solids dissolved to form a dark red solution, and subsequently an orange solid precipitated.  After two hours, the solid was vacuum filtered and dissolved in minimal hot DMF/acetonitrile solution (1:1, ~10 mL).  Ether (10 mL) was added to the solution and it was cooled to 4ºC overnight.  A dark red precipitate formed and was vacuum filtered. Yield: 400 mg, 73%.  Crystals suitable for X-ray diffraction were grown from an acetonitrile/DMF/ether solution. 1H NMR (400 MHz, CD2Cl2): δ 8.16 (m, 4H), 7.49 (m, 4H), 7.44 (s, 2H), 7.34 (m, 14H), 6.97 (d, 2H, J = 5.2Hz), 1.11 (s, 3H).  31P{1H} NMR (162 MHz, CD2Cl2): δ 8.7 (s).  ESI-MS m/z 753 ([M-CH3CN-Cl] +). Anal. Calcd for (C38H29Cl2NP2RuS3)·(C3H7NO): C, 54.54; H, 4.02; N, 3.10.  Found: C, 54.85; H, 4.08; N, 3.16.  Ru(P2T3)Cl2(4,4'-bpy) (106). A slurry of Ru(P2T3)(CH3CN)Cl2·DMF (100 mg, 0.11 mmol) and 4,4'-bpy·2H2O (50 mg, 0.26 mmol) in acetone (20 mL) was heated to reflux for four hours.  The solution was cooled and filtered through neutral alumina resulting in a green solution. The solution was concentrated to 1 – 2 mL, and the resulting precipitate vacuum filtered.  Yield: 20 mg, 19%.   1H NMR (300 MHz, CD2Cl2) δ 8.74 (m, 1H), 8.65 (m, 1H), 8.49 (d, 1H, J=6.3Hz), 8.14 (m, 4H), 7.88 (d, 2H, J = 6.3Hz), 7.63 (d, 1H, J = 5.4Hz), 7.54 (s, 2H), 7.35 (m, 8H), 7.22 (d, 1H, J = 5.4Hz), 7.03 (m, 2H), 6.94 (m, 4H), 6.85 (m, 6H), 6.38 (m, 1H), 6.35 (m, 1H). 31P{1H} NMR (121 MHz, CD2Cl2) δ 8.3 (s).  ESI-MS m/z 909 ([M-Cl]+).  Anal. Calcd for (C47H36Cl2N2P2RuS3)·2H2O: C, 56.32; H, 3.90; N, 2.86.  Found: C, 56.17; H, 3.86; N, 2.89.   [Ru(P2T3)Cl2(N-Me-4,4'-bpy)][I] (107). In a 50 mL round bottom flask, Ru(P2T3)Cl2(CH3CN)·DMF (100 mg, 0.11 mmol) and  N- Me-4,4'-bipyridinium iodide (33 mg, 0.11 mmol) were ground together to make a homogeneous mixture.  The mixture was then heated to 100ºC under nitrogen.  A vapour of CH3CN condensed  122 around the top of the round bottom flask during the two hours that it was heated.  The mixture was cooled overnight, then dissolved in CHCl3 and filtered.  The solution was evaporated, leaving a brown solid. Yield: 106 mg, 88%.     1H NMR (CDCl3, 400 MHz) δ 9.19 (m, 2H), 8.80 (d, 2H, J = 4.4 Hz), 8.10 (m, 2H), 8.02 (quart, 4H, J = 5.7 Hz), 7.64 (m, 4H), 7.60 (m, 2H), 7.46 (s, 2H), 7.42 (m, 1H), 7.35 (m, 5H), 7.28 (d, 2H, J = 5.2Hz), 7.20 (m, 1H), 7.14 (t, 2H, J = 7Hz), 7.07 (t, 3H, J = 7.2 Hz), 6.90 (d, 2H, J = 5.2 Hz), 4.22 (s, 3H).  31P{1H} NMR (162 MHz, CDCl3) δ 7.4 (s).  ESI-MS m/z 959 ([M-I] +).  Anal. Calcd for (C47H37Cl2IN2P2RuS3)·H2O: C, 51.09; H, 3.56; N, 2.54.  Found: C, 51.38; H, 4.01; N, 2.67.  [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109). Ru(2,2'-bpy)Cl2(DMSO)2 (485 mg, 1.00 mmol), AgBF4 (214 mg, 1.10 mmol) and P2T3 (617 mg, 1.00 mmol) in a CHCl3 solution (300 mL) were heated to reflux overnight.  The reaction was then cooled to room temperature, filtered through Celite, and the Celite washed with CH2Cl2.  The filtrate was evaporated and the residue dissolved in a minimal amount of acetone.  The acetone was added to an aqueous solution of NH4PF6, resulting in an immediate orange precipitate.  The mixture was stirred for one hour and the precipitate was vacuum filtered. The precipitate was purified by chromatography on neutral alumina, using first CH2Cl2, followed by acetone. Yield: 326 mg, 31%.  Crystals suitable for single crystal X-ray diffraction were grown from acetone/MeOH/hexanes. 1H NMR (400 MHz, CDCl3):  δ 9.12 (d, 1H, J = 5.6Hz), 8.02 (d, 1H, J = 8Hz), 7.87 (t, 1H, J = 7.6), 7.79 (d, 1H, J = 8.4Hz), 7.77 (d, 1H, J = 5.6Hz), 7.61 (t, 1H, J = 8Hz), 7.56 (s, 2H), 7.46 (m, 5H), 7.30 (m, 4H), 7.24 (d, 2H, J = 7.2Hz), 7.15 (t, 4H, J = 7.2Hz), 6.82 (t, 4H, J = 8Hz), 6.63 (d, 2H, J = 5.2Hz), 6.59 (t, 1H, J = 6Hz), 6.20 (m, 4H). 31P{1H} NMR (162 MHz, CDCl3) δ 9.5 (s), -141.8 (sept).  ESI-MS m/z 909 ([M-PF6] +).  Anal. Calcd for C46H34ClF6N2P3RuS3: C, 52.40; H, 3.25; N, 2.66.  Found: C, 52.57; H, 3.41; N, 2.62.   [Ru(P2T3)(tpy)][PF6]2 (110). Ru(tpy)Cl2(DMSO) (78 mg, 0.16mmol) and AgBF4 (197 mg, 0.32 mmol) were dissolved in methanol (30 mL) and heated to reflux for nine hours.  The solution was cooled to room temperature, filtered, and the filtrate added to a suspension of P2T3 (100 mg, 0.16 mmol) in MeOH (30 mL).  The mixture was heated to reflux and stirred overnight.  The solution was then cooled to room temperature and added to a water solution (50 mL) containing NH4PF6 (130 mg,  123 0.798 mmol).  Immediately, an orange solid precipitated.  The precipitate was stirred for one hour and the product was isolated by vacuum filtration.  Yield: 102 mg, 51%. Crystals suitable for X-ray diffraction were grown from slow evaporation of a hexanes/acetone solution.  1H NMR (400 MHz, d6-acetone) δ 8.46 (s, 3H), 8.21 (s, 2H), 7.90 (m, 4H), 7.78 (m, 4H), 7.26 (m, 6H), 7.02 (m, 8H), 6.65 (m, 10H).  31P{1H} NMR (161 MHz, d6-acetone) δ 9.7 (s), -141.8 (sept, J = 702 Hz).  EI-MS: m/z 1096 ([M-(PF6)] +), 475 ([M-(PF6)2] 2+).  Anal. Calcd for C51H37F12N3P4RuS3: C, 49.36; H, 3.01; N, 3.39 %. Found: C, 49.4; H, 3.31; N, 2.97.   [Ru(P2T3)Cl(CH3CN)2][PF6] (108). Ru(DMSO)4Cl2 (39 mg, 0.081 mmol), AgBF4 (33 mg, 0.17 mmol) and P2T3 (100 mg, 0.16 mmol) were dissolved in acetonitrile (100 mL) and heated to reflux overnight.  The solution was cooled to room temperature and then filtered through Celite.  The Celite was rinsed with acetone and the filtrate evaporated until approximately 10 mL of solvent remained.  The reduced filtrate was then filtered through glass wool and added to a solution of NH4PF6 in water. Immediately, a yellow precipitate was observed, and after thirty minutes the precipitate was vacuum filtered.  The yellow precipitate was then recrystallized in CHCl3 and vacuum filtered. Yield: 10 mg, 13%.  1H NMR (300 MHz, d6-acetone) δ 7.85 (d, J = 5.4 Hz, 2H), 7.78 (s, 2H), 7.70 (m, 6H), 7.50 (m, 14H), 7.01 (d, J = 5.4 Hz, 2H), 2.77 (s, 6H).  31P{1H} NMR (121 MHz, d6-acetone) δ 8.0 (s), -141 (sept).  MALDI-TOF: m/z 835 ([M-PF6] +).  Anal. Calcd for C40H32ClN2P3RuS3F6: C, 49.01; H, 3.29; N, 2.86.  Found: C, 48.65; H, 3.37; N, 2.58.  IR 2283.9 cm -1  (ν(C≡N)).  Ru(P2T5)Cl2(DMSO) (111). Ru(DMSO)4Cl2 (51.0 mg, 0.105 mmol) and P2T5 (100 mg, 0.105 mmol) were added to N2(g) sparged toluene (3 mL).  The mixture was heated to reflux for 2 hours.  The toluene was removed in vacuo, the residue dissolved in CHCl3 and the CHCl3 solution was added to Et2O to precipitate a red powder.  The slurry was centrifuged and the precipitate was rinsed 3 times with 10 mL of Et2O (3 × 10 mL).  Yield: 40 mg, 30%. 1H NMR (300 MHz, CDCl3) δ 8.16 (m, 2H), 7.75 (m, 4H), 7.43 (s, 2H), 7.38 (m, 8H), 7.21 (m, 8H), 6.92 (d, J = 5.4 Hz, 2H), 6.89 (s, 2H), 2.59 (m, partially overlaps with free DMSO), 1.84 (s, overlaps with alkyl chain protons), 1.80 (m, overlaps with bound DMSO peak), 1.50 (m, 5H), 0.84 (t, 6H, J = 6.6 Hz).  31P{1H} NMR  124 (121 MHz, CDCl3) δ 1.9 (s).  ESI-MS: m/z 1087 ([M-Cl-DMSO] +).  Anal. Calcd for C58H60Cl2OP2RuS6·CH3Cl: C, 53.73; H, 4.66.  Found: C, 53.27; H, 4.62.  IR 1015.0 cm -1  (ν(S=O)).   [Ru(P2T5)(tpy)][PF6]2 (112). Ru(tpy)Cl2(DMSO) (86 mg, 0.18 mmol) and AgBF4 (73 mg, 0.37 mmol) were added to methanol (50 mL) and the solution heated to reflux for 15 hours.  The solution was cooled to room temperature and filtered into a round bottom containing P2T5 (169 mg, 0.178 mmol).  The solution was heated to reflux for 24 hours and cooled to room temperature.  The MeOH solution was added to a solution of NH4PF6 (290 mg) in water and an orange precipitate immediately appeared.  The orange precipitate was vacuum filtered to obtain the crude product (156 mg). The product was crystallized from MeOH/hexanes.  Yield: 20 mg, 7.1%.    1H NMR (400 MHz, d6-acetone) δ 8.47 (s, 3H), 8.24 (s, 2H), 7.98 (d, 2H, J = 5.9 Hz), 7.91 (d, 2H, J = 7.8 Hz), 7.43 (d, 2H, J = 5.4 Hz), 7.29 (t, 6H, J = 7.8), 7.06 (t, 8H, J = 7.8 Hz), 6.99 (d, 2H, J = 5.9 Hz), 6.76 (q, 7H, J = 5.3 Hz), 6.54 (s, 2H), 2.46 (t, 4H, J = 7.8 Hz), 1.32 (m, 4H), 1.11 (m, 4H), 1.02 (m, 8H), 0.75 (t, 6H, J = 7.0 Hz).  31P{1H} NMR (121 MHz, d6-acetone) δ 10.1 (s), -147.1 (sept). ESI-MS: m/z 1428 ([M-PF6] +).  Anal. Calcd for C71H65F12N3P4RuS5: C, 54.19; H, 4.16; N, 2.67. Found: C, 53.79; H, 4.24; N, 2.71.  Section 5.2.3 – X-Ray Crystallography All crystals were mounted on glass fibers.  The crystal structure data was obtained and the structures solved by Dr. B. O. Patrick. All measurements were made on a Bruker X8 APEX II diffractometer with graphite monochromated Mo-Kα radiation. Data were collected and integrated using the Bruker SAINT106 software package. Data were corrected for absorption effects using the multi-scan technique (SADABS107).  The data were corrected for Lorentz and polarization effects.  The structures were solved by direct methods.108 Diagrams were made using ORTEP-3, 109  and POV-RAY. 110     125 Ru(P2T3)Cl2(CH3CN)·DMF (105).  The data were collected to a maximum 2θ value of 47.8°. Data were collected in a series of φ and ω scans in 0.50° oscillations with 15.0 second exposures.  The crystal-to-detector distance was 36.00 mm. Of the 28819 reflections that were collected, 11495 were unique (Rint = 0.034); equivalent reflections were merged.  The minimum and maximum transmission coefficients were 0.791 and 0.952, respectively.  The material crystallizes with two independent Ru complexes in the asymmetric unit.  Additionally there are two molecules of DMF in the asymmetric unit.  One DMF molecule was disordered and was modeled in two orientations.  All non-hydrogen atoms except those in the disordered DMF molecule were refined anisotropically. All hydrogen atoms were placed in calculated positions but were not refined.  The material also crystallizes as a racemic twin.  The SHELXL TWIN/BASF functions were used to model the ratio of twin components accordingly.  The final cycle of full-matrix least-squares refinement on F2 was based on 11495 reflections and 931 variable parameters and converged.  [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109).  The data were collected to a maximum 2θ value of 55.9°. Data were collected in a series of φ and ω scans in 0.50° oscillations with 10.0-second exposures. The crystal-to-detector distance was 36.00 mm.  Of the 76558 reflections that were collected, 20031 were unique (Rint = 0.043); equivalent reflections were merged.  Data were corrected for absorption effects with minimum and maximum transmission coefficients of 0.898 and 0.950, respectively.  The material crystallizes with two independent molecules in the asymmetric unit.  There is a small fraction of disorder regarding the orientation of the terthiophene moiety in each molecule.  This disorder was modeled using restraints on bond lengths and angles such that the minor fragments had geometries similar to those of the major fragments.  All non-hydrogen atoms in the major fragments were refined anisotropically.  All hydrogen atoms were placed in calculated positions but were not refined.  The final cycle of full-matrix least-squares refinement on F2 was based on 20031 reflections and 1244 variable parameters, and converged.     126 [Ru(P2T3)(tpy)][PF6]2·0.63H2O (110).  The data were collected to a maximum 2θ value of 56.1°. Data were collected in a series of φ and ω scans in 0.50° oscillations with 20.0 second exposures. Of the 105257 reflections that were collected, 12056 were unique (Rint = 0.072); equivalent reflections were merged.  Data were corrected for absorption effects with minimum and maximum transmission coefficients of 0.798 and 0.937, respectively. All non-hydrogen atoms were refined anisotropically.  Two phenyl rings on P1 are disordered and were each modeled in two orientations.  Additionally, one PF6 - anion is disordered, with all six fluorine atoms modeled in two orientations.  Restraints were employed to maintain reasonable octahedral geometry about the P atom.  Finally, a water molecule is found at one site in the asymmetric unit.  This site is only partially occupied (the relative population is 0.63) and no hydrogen atoms could be located in a difference map.  All hydrogen atoms were placed in calculated positions.  The final formula and values derived from it are based on the presence of 0.63 molecules of H2O. The final cycle of full-matrix least- squares refinement on F2 was based on 12056 reflections and 790 variable parameters and converged.  Section 5.3 Results and Discussion  Section 5.3.1 – Design and Synthesis  Ru(P2T3)Cl2(DMSO) was synthesized by combining P2T3 and Ru(DMSO)4Cl2  in toluene and heating the mixture to reflux (Scheme 5-1), similar to the procedure used to prepare other Ru(II) phosphine complexes.233 An orange precipitate gradually appeared which indicated product formation. Although single crystals were not obtained, the IR of Ru(P2T3)Cl2(DMSO) had a ν(S=O) absorption band at 1009 cm-1, indicating that the DMSO was O bound. Complexes with coordinated O of DMSO typically have ν(S=O) bands at lower energy than free DMSO and appear between 1025 - 985 cm-1.234 When DMSO is bound via the S, as in Ru(DMSO)4Cl2, the ν(S=O) bands appear at higher wavenumbers, between 1120 - 1095 cm -1.234 The steric bulk of P2T3 on Ru(II) may inhibit the formation of a Ru-S bond. To determine the effects of increasing the ligand conjugation length by using a pentathiophene rather than terthiophene backbone, Ru(P2T5)Cl2(DMSO) was synthesized.  This complex was also prepared by heating Ru(DMSO)4Cl2 and P2T5 in toluene to reflux.  The  127 presence of the hexyl chains on the pentathiophene resulted in Ru(P2T5)Cl2(DMSO) being soluble in toluene.  Removal of the toluene, followed by dissolving the residue in CHCl3 and adding it to diethyl ether resulted in Ru(P2T5)Cl2(DMSO) precipitating.  The DMSO is also O- bound to Ru(II), as evident from the ν(S=O) band at 1015 cm-1 in the IR spectrum.  Scheme 5-1.    Modifying the neutral Ru(P2T3) complexes with other ligands was straightforward, but sensitive to solvent.  To exchange DMSO for CH3CN, Ru(P2T3)Cl2(DMSO) was dissolved in hot DMF/CH3CN (1:1).  Addition of diethyl ether to the DMF/CH3CN solution and cooling to 4ºC yielded Ru(P2T3)Cl2(CH3CN). The CH3CN in Ru(P2T3)Cl2(CH3CN) was displaced by 4,4'-bpy in hot acetone to give Ru(P2T3)Cl2(4,4'-bpy).  Interestingly, synthesis of [Ru(P2T3)Cl2(N-Me-4,4'- bpy)][I] was accomplished by a solvent free synthesis in which a solid mixture of Ru(P2T3)Cl2(CH3CN) and [N-Me-4,4'-bpy][I] was heated to exchange the CH3CN for (N-Me- 4,4'-bpy) (Scheme 5-2).   128 Scheme 5-2.   The geometry around Ru(II) in the neutral complexes (110 – 113, and 117) could be either cis or trans with respect to the –Cl- groups.  Far IR spectra can sometimes be used to differentiate between cis- and trans- isomers of RuCl2 complexes by determining the number of Ru-Cl bands present, but here the Ru-S and Ru-P bands overlap with the Ru-Cl bands.  Analysis of the far IR spectra of the neutral complexes was inconclusive as to whether exclusively cis, trans, or mixtures of isomers were obtained.  For convenience, Ru(P2T3)Cl2(DMSO), Ru(P2T3)Cl2(4,4'-bpy), and [Ru(P2T3)Cl2(N-Me-4,4'-bpy)][I] are all arbitrarily shown in the schemes as the cis-isomer. Their purification was considered complete when only one peak was observed in the 31P{1H} NMR spectrum.  The specific isomers obtained in dichloro-Ru(II) complexes are known to depend on the ligands around Ru(II), solvent and temperature.235 To further extend the library of Ru(P2T3) and Ru(P2T5) complexes to include cationic species, [Ru(P2T3)(CH3CN)2Cl][PF6], [Ru(P2T3)(2,2'-bpy)Cl][PF6], [Ru(P2T3)(tpy)][PF6]2 and [Ru(P2T5)(tpy)][PF6]2 were synthesized.  In addition, [Ru(P2T3)(2,2'-bpy)Cl][PF6] and [Ru(P2T3)(tpy)][PF6]2 each have only one possible isomer that allows more conclusive structural characterization.  129 The synthesis of all four cationic complexes required dehalogenation with AgBF4 (Scheme 5-3 and Scheme 5-4).  [Ru(P2T3)(tpy)][PF6]2 and [Ru(P2T5)(tpy)][PF6]2 were synthesized via dehalogenation of Ru(tpy)Cl2(DMSO) in MeOH prior to addition of P2T3 and P2T5 respectively.  In the case of [(Ru(P2T3)(2,2'-bpy)Cl][PF6] and [(Ru(P2T3)(CH3CN)2Cl][PF6], by contrast, the appropriate Ru(II) starting material was directly reacted with P2T3 in one step, in CHCl3 and CH3CN solutions respectively.  Interestingly, despite the presence of excess P2T3 and AgBF4 in the synthesis of [(Ru(P2T3)(CH3CN)2Cl][PF6], there was no evidence for formation of Ru(II) complexes containing more than one P2T3 ligand, such as [(Ru(P2T3)2][PF6]2.  The IR spectrum contained only one band attributable to ν(C≡N), suggesting a high symmetry species had formed.  It is possible that other ν(C≡N) bands were obscured by ν(CO) of CO2(g).  The 1H NMR spectrum of [(Ru(P2T3)(CH3CN)2Cl][PF6] contained one singlet at 2.77 ppm, indicating that the -CH3 groups of the coordinated CH3CN are chemically equivalent in solution.  Hence, [(Ru(P2T3)(CH3CN)2Cl][PF6] is proposed as the trans isomer.  The low yield of [(Ru(P2T3)(CH3CN)2Cl][PF6] is surprising, given that the 1H and 31P{1H} NMR spectra of the crude reaction mixture both suggest the isolated [(Ru(P2T3)(CH3CN)2Cl][PF6] is the major product. It is possible that the steric bulk of P2T3 prevented further dehalogenation of the Ru(II) centre.  The solutions were either concentrated or the solvent was removed in vacuo, the residue dissolved, and the solution was directly added to a water solution with excess NH4PF6 to metathesize the complex and precipitate the product.  Scheme 5-3.     130 Scheme 5-4.   Section 5.3.2 – Solid-State Molecular Structures Single crystals of Ru(P2T3)Cl2(CH3CN)·DMF suitable for X-ray diffraction were grown from a DMF/CH3CN/Et2O solution, and the solid-state structure of one molecule of Ru(P2T3)Cl2(CH3CN) is shown in Figure 5-2.  In the solid-state, there are two crystallographically unique Ru(P2T3)Cl2(CH3CN) molecules each with bond lengths and angles within experimental error of the other (Table 5-1 and Appendix Table A1-7). As anticipated, P2T3 binds as a tridentate ligand to Ru(II).  The octahedral geometry around the Ru(II) centre is consistent with the preferred geometry for d6 metal ions.  Similar trans-bisphosphine molecules complexes also have an octahedral geometry at Ru(II), such as trans- bis(triphenylphosphine)benzaldimine-Ru(II) that has a P-Ru-P angle of 177.76(7)°.236  The Ru(II) centre in Ru(P2T3)Cl2(CH3CN) forms two six-membered rings, as observed in other phosphino-oligothienyl-Ru(II) complexes bonded through the thiophene S.86,94 The torsion angle between adjacent thiophene rings is similar (154.4(3)° and -153.2(3)°).  Ru(P2T3)Cl2(CH3CN) therefore has approximate Cs symmetry at the metal centre (neglecting the phenyl rings of the aryl phosphines).  The Ru-S bond is 2.2486(12) Å; significantly shorter than observed in cis-  131 Ru(PT3)(dppm)Cl2 that has a Ru-S bond length of 2.3068(9) Å. 173  Ru(P2T3)Cl2(CH3CN)·DMF packs with a series of slipped π-interactions between S1 and S2 thiophenes and S3 and S6 thiophenes (between the crystallographically unique complexes).   Figure 5-2.  Solid-state molecular structure of one molecule of Ru(P2T3)Cl2(CH3CN) (105). Occluded DMF and H atoms omitted for clarity.  Thermal ellipsoids drawn at 50% probability.   Figure 5-3.  Solid-state molecular structure of one molecule of [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109).  H atoms and [PF6] - counterion omitted for clarity and thermal ellipsoids drawn at 50% probability.  132  Table 5-1.  Selected bond lengths (Å) and angles (º) for one of the two molecules of Ru(P2T3)Cl2(CH3CN)·DMF (105) in the unit cell. Bond Lengths (Å) P1-Ru1 2.3675(13) P2-Ru1 2.3672(13) S2-Ru1 2.2486(12) Ru1-N1 1.994(5) Cl1-Ru1 2.4302(13) Cl2-Ru1 2.4015(12) C5-S2 1.748(5) C8-S2 1.737(5) C5-C6 1.362(7) C6-C7 1.400(7) C7-C8 1.375(7) C8-C9  1.439(7) C10-P2 1.827(5) C3-P1 1.823(5) C37-N1 1.151(7) C37-C38 1.427(9) Angles (o) C8-S2-C5 92.5(2) C6-C5-S2 109.3(4) C5-C6-C7 114.1(5) C8-C7-C6  114.1(5) C7-C8-S2 109.2(4) C3-P1-Ru1  117.24(15) C13-P1-Ru1 118.82(16) C19-P1-Ru1 111.25(14) C10-P2-Ru1 116.70(16) C31-P2-Ru1 110.26(15) C25-P2-Ru1  119.27(16) P2 Ru1 P1  176.50(5) S2 Ru1 Cl2  177.89(5) N1 Ru1 Cl1  177.83(12) Torsion Angles (o) S1-C4-C5-S2 154.4(3) S2-C8-C9-S3 -153.2(3)   Single crystals of [Ru(P2T3)(2,2'-bpy)Cl][PF6] were obtained from acetone/MeOH/hexanes solution and the solid-state structure of one of the molecules in the unit cell is shown in Figure 5-3.  There are two crystallographically unique [Ru(P2T3)(2,2'- bpy)Cl][PF6] molecules with similar bond lengths and angles (Table 5-2 and Appendix Table A1-8) in the unit cell.  There is small disorder between the terthiophene and Cl groups where the central thiophene replaces the Cl and vice versa.  There was also disorder present in two of the phenyl rings. As in Ru(P2T3)Cl2(CH3CN), the P2T3 is again bonded to the Ru(II) in a tridentate manner and the ligands arrange in an octahedral geometry around the Ru(II) centre.  No mirror plane is present in [Ru(P2T3)(2,2'-bpy)Cl][PF6] however, as evident by the significantly different torsion angles between the central thiophene with either terminal thiophene (172.0(2)° and  133 133.8(3)°, Table 5-2).  The Ru-S distance is 2.282(9) Å, which is lengthened compared to the Ru-S distance in Ru(P2T3)Cl2(CH3CN).  This is still shorter than in similar Ru-polypyridine systems  where the bond length ranges from 2.3578(14) Å94 and 2.3640(8) Å.94  No exceptional packing was found in the solid-state structure.  Table 5-2.  Selected bond lengths (Å) and angles (º) for one molecule of the molecules of [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109) in the unit cell. Bond Lengths (Å) Ru1-P1 2.3675(10) Ru1-P2 2.3968(10) Ru1-Cl1 2.4079(10) S2-Ru1 2.2820(9) N1-Ru1 2.075(3) N2-Ru1 2.061(3) C5-S2 1.756(4) C8-S2 1.738(4) C5-C6 1.367(5) C6-C7  1.426(6) C7-C8 1.360(5) C8-C9 1.448(5) Angles (o) C8-S2-C5 92.99(18) C6-C5-S2 108.7(3) C5-C6-C7  114.0(4) C8-C7-C6 114.0(4) C7-C8-S2 109.5(3) C3-P1-Ru1 113.99(14) C23-P1-Ru1 115.10(11) C29-P1-Ru1 114.36(11) P1-Ru1-P2 175.80(3) N2-Ru1-Cl1 174.91(8) N1-Ru1-S2 173.64(8) Torsion Angles (o) S1-C4-C5-S2  172.0(2) S2-C8-C9-S3  -133.8(3)   Single crystals of [Ru(P2T3)(tpy)][PF6]2 were grown from a hexanes/acetone solution and its solid-state molecular structure is shown in Figure 5-4.  Disorder was present in two of the phenyl rings and in one of the PF6 - anions. P2T3 binds to Ru(II) as a tridentate ligand and Ru(II) is in octahedral as in Ru(P2T3)(CH3CN)Cl2 and [Ru(P2T3)(2,2'-bpy)Cl][PF6].  The torsion angles along the terthiophene are similar between the central thiophene and the terminal thiophenes (141.1(3)o and -144.6(3)o (Table 5-3)) and comparable to both Ru(P2T3)(CH3CN)Cl2 and [Ru(P2T3)(2,2'-bpy)Cl][PF6].  A quasi-mirror plane can be drawn along the tpy, intersecting the central thienyl ring of [Ru(P2T3)(tpy)][PF6]2 giving it approximately Cs symmetry. [Ru(P2T3)(tpy)][PF6]2 has a Ru-S bond length of 2.3309(12) Å, the longest in the three Ru(II)  134 complexes described here.  This bond length is still shorter than in related phosphino-thienyl- Ru(II)-polypyridine complexes.94 No exceptional packing was observed in the solid-state molecular structure.  Figure 5-4.  Solid-state molecular structure of [Ru(P2T3)(tpy)][PF6]2·0.63 H2O (110).  H atoms, occluded solvent and [PF6] - counterions omitted for clarity. Table 5-3.  Selected bond lengths (Å) and angles (º) for [Ru(P2T3)(tpy)][PF6]2·0.63 H2O (110). Bond Lengths (Å) N1-Ru1 2.092(4) N2-Ru1 1.975(4) N3-Ru1 2.079(4) S2-Ru1 2.3309(12) P1-Ru1 2.3967(12) P2-Ru1 2.3826(12) C5-S2 1.740(5) C8-S2 1.743(5) C5-C6 1.358(8) C6-C7 1.417(7) C7-C8 1.353(7) C8-C9 1.440(6) Angles (o) C5-S2-C8  92.0(2) C6-C5-S2 110.0(4) C5-C6-C7 113.8(5) C8-C7-C6 113.5(5) C7-C8-S2 110.3(4) C3-P1-Ru1 117.73(17) C19-P1-Ru1 116.3(3) C13-P1-Ru1 109.5(3) N3-Ru1-N1 158.57(16) N2-Ru1-S2 177.36(13) P2-Ru1-P1 178.92(5) Torsion Angles (o) S1-C4-C5-S2 141.1(3) S2-C8-C9-S3 -144.6(3)   135 Section 5.3.3 – Electronic Absorption Spectra  The electronic effect of the ligands, charge and conjugation length in the series of Ru(II) complexes was probed with solution UV-vis absorption spectra (Table 5-4, Figure 5-5).  Table 5-4.  Electronic absorption data for Ru(II)-phosphino-oligothiophene complexes. Compound λmax /nm (ε /M -1cm-1) Ru(P2T3)Cl2(DMSO) (104) 268 (28 000), 395 (11 000), 446 (sh) (4 000) a Ru(P2T5)Cl2(DMSO) (111) 265 (34 000), 414 (17 000) a Ru(P2T3)Cl2(CH3CN) (105) 260 (42 000), 392 (15 000), 448 (sh) (3000) a Ru(P2T3)Cl2(4,4´-bpy) (106) 260 (45 000), 393 (15 000), 450 (sh) (3300) a [Ru(P2T3)Cl2(N-Me-4,4´-bpy)][I] (107) 257 (45 000), 387 (11 000), 447 (sh) (3000) a [Ru(P2T3)Cl(CH3CN)2][PF6] (108) 260 (43 000), 384 (14 000), 434 (sh) (3300) b [Ru(P2T3)(2,2´-bpy)Cl][PF6] (109) 259 (39 000), 300 (sh) (16 000), 378 (14 000), 416 (sh) (9300)b [Ru(P2T3)(tpy)][PF6]2 (110) 259 (41 000), 296 (sh) (24 000), 333 (18 000), 387 (15 000)b [Ru(P2T5)(tpy)][PF6]2 (112) 263 (49 000), 297 (37 000), 333 (25 000), 445 (30 000)b Ru(PT3-P,S)2Cl2 (100) 356 (br) (21 300) c cis-Ru(PT3-P,S)(dppm)Cl2 (102) 322 (11 700), 374 (17 800), 510 (1 100) c trans-Ru(PT3-P,S)(dppm)Cl2 (103) 316 (sh) (11 400), 382 (14 800), 518 (291) c Ru(PT3)2Cl2(CO) (101) 238 (122 000), 254 (sh) (117 000), 286 (sh) (82 100), 346 (66 500)c [Ru (2,2´-bpy)2(PT3-P,S)][PF6]2 (39) 280 (37 900), 320 (sh) (18 300), 393 (18 000) d [Ru(2,2´-bpy)2(PT5-P,S)][PF6]2 (98) 280 (42 700), 323 (sh) (22 400), 371 (20 700), 465 (26 800)d a In CH2Cl2. b In CH3CN. c From Ref.173 d From Ref.94   The absorption spectra of the Ru(II) complexes synthesized here (104 – 112) are dominated by π-based transitions.  All of the complexes have a π  π* transition at 260 nm,  136 which is slightly red-shifted from the ππ* band in P2T3 (253 nm).  Remarkably, between 350- 550 nm there is little difference in the spectra of the Ru(P2T3) complexes (104 - 110). The neutral Ru(P2T3) complexes (104 - 107) each have a strong band at ~390 nm.  This absorption band is bathochromically shifted with respect to the lowest energy band of P2T3 (λmax = 360 nm).  Similarly, cis-Ru(PT3-P,S)(dppm)Cl2 and trans-Ru(PT3-P,S)(dppm)Cl2 have π-based transitions on the terthiophene at 374 and 382 nm respectively that are red-shifted from the absorbance band in PT3. 173 This bathochromic shift was previously attributed to the Ru(II) donating electron density to the terthiophene and the increased rigidity of the oligothiophene as a result of coordination to the metal,173 and a similar effect is likely involved in the electronic spectra of the Ru(II) complexes studied here.  The lowest energy bands in [Ru(P2T3)(CH3CN)2Cl][PF6], [Ru(P2T3)(2,2'-bpy)Cl][PF6] and [Ru(P2T3)(tpy)][PF6]2 are hypsochromically shifted from the comparable bands in the neutral complexes.  The similarity in the absorption maxima to the neutral complexes (104 - 107) suggests that these transitions also have π-character.  Previous studies on [Ru(PT3-P,S)(2,2´- bpy)2][PF6]2 attributed the band at 393 nm as a MLCT transition. 94 [Ru(P2T3)(2,2'-bpy)Cl][PF6] and [Ru(P2T3)(tpy)][PF6]2 also have chelating polypyridines, so it is possible that there is a MLCT component in addition to a ππ* component for the lowest energy band.  To elucidate whether MLCT transitions partially contributed to the observed bands, the electronic absorption spectra were recorded in solvents of different polarity (toluene, CH2Cl2, MeOH, THF and acetonitrile where possible). The lowest energy band of [Ru(P2T3)(tpy)][PF6]2 shifted from 408 nm in toluene to 386 nm in THF, which suggests that this band may indeed have some charge transfer contribution.  In [Ru(P2T3)(2,2'-bpy)Cl][PF6], the band at 378 nm was solvent independent, whereas the shoulder shifted from 412 nm in THF to 423 nm in toluene.  The solvent sensitivity of the shoulder suggests that MLCT contributions are responsible for this band.  All of the other complexes’ bands were solvent independent.  [Ru(P2T3)(tpy)][PF6]2 and [Ru(P2T3)(2,2'-bpy)Cl][PF6] had additional bands between 280 nm – 350 nm.  The bands at 296 nm and 333 nm in [Ru(P2T3)(tpy)][PF6]2 are red-shifted from those of [Ru(tpy)2] 2+ (λ = 269 and 308 nm) that is similar to Ru(tpy) complex ions with other ligands such as [Ru(tpy)(pydppz)]2+ (pydppz = 3-(pyrid-2'-yl)dipyrido[3,2-a: 2,3'-c] phenazine)237 and [Ru(tpy)(tripy)]2+ (tripy = 2,6- bis(1H-1,2,3-triazol-4-yl)pyridine).238 Likewise, the transitions on [Ru(P2T3)(2,2'-bpy)Cl][PF6] are similar to cis-Ru(2,2'-bpy)2Cl2 239 (λmax = 340 nm, 400 – 500 nm (MLCT)), [Ru(2,2'-  137 bpy)(tpy)Cl]+,240 (λmax = 292 nm, 316 nm, 501 nm (MLCT)) and [Ru(PT3-P,S)(2,2´- bpy)2][PF6]2. 94  Increasing the number of thienyl rings in the ligand led to a bathochromic shift in the lowest energy absorption band for Ru(P2T5)Cl2(DMSO) and [Ru(P2T5)(tpy)][PF6]2 compared to the Ru(P2T3) complexes.   This large shift in the lowest energy band suggests that it is dominated by ππ* transitions on P2T5.  Furthermore, the bands were all solvent-independent, which is consistent with ππ* character.  The higher energy bands for Ru(P2T5)Cl2(DMSO) and [Ru(P2T5)(tpy)][PF6]2 are identical to those in Ru(P2T3)Cl2(DMSO) and [Ru(P2T3)(tpy)][PF6]2, suggesting that these transitions are not localized on the oligothiophene.    138  Figure 5-5.  Solution absorption spectra of a) neutral complexes (104 – 107, 111) in CH2Cl2 and b) cationic complexes (108 – 110, 112) in CH3CN.   139  Low temperature absorption spectra of the complexes were obtained for further insight into the electronic structure of the complexes (Figure 5-6 and Figure 5-7).  All of the complexes show no shifts in their absorbance bands when cooled to 85 K from room temperature.  This suggests that there is no significant change in planarity of the terthienyl groups over this temperature range. Cooling enhances the vibronic coupling in most of the complexes, consistent with the presence of a delocalized electronic system. In the neutral complexes (104 – 107, 111) the lowest energy band at ~390 nm separates into 2 bands at 85 K.  In Ru(P2T3)Cl2(CH3CN) and Ru(P2T3)Cl2(DMSO) the lowest energy bands separates by ~1100 cm -1, while the comparable bands in Ru(P2T3)Cl2(4,4'-bpy) and [Ru(P2T3)Cl2(N-Me-4,4'-bpy)][I] separate by 960 cm -1. These separations are typical of vibrational coupling with the thienyl groups.120,121  Alternatively, it is possible that these bands are due to cis and trans isomers.  Different isomers can have different absorbance bands as seen in cis-Ru(PT3-P,S)(dppm)Cl2 and trans-Ru(PT3- P,S)(dppm)Cl2 that have slightly different π absorption bands at 374 nm and 382 nm, respectively.173   Lengthening the conjugation in Ru(P2T5)Cl2(DMSO) results in notable changes in the low temperature absorption features where the lowest energy band split into two bands separated by ~2300 cm-1.  The large energy difference between the bands in Ru(P2T5)Cl2(DMSO) suggests that two different electronic states, rather than vibrational coupling, are responsible for the two bands. The cationic complexes (108 – 110, 112) show similar features to the neutral (104 – 107, 111) complexes.  The band at 385 nm in [Ru(P2T3)(CH3CN)2Cl][PF6] separates into two bands with a ~1000 cm-1 difference at 85 K.  The shoulder at 423 nm for [Ru(P2T3)(2,2'-bpy)Cl][PF6] becomes more resolved at 85 K.  In both [Ru(P2T3)(2,2'-bpy)Cl][PF6] and [Ru(P2T3)(tpy)][PF6] the single band at 385 nm at room temperature, have two shoulders at 85 K that were separated by separated by ~1200 cm-1.  This energy difference is consistent with either thienyl or polypyridyl vibrational coupling.120,121,241 Extending the conjugation in the cationic complexes in [Ru(P2T5)(tpy)][PF6]2 afforded similar results, where the lowest energy band had vibrational shoulders separated by ~1100 cm-1.  140  Figure 5-6.  UV-vis absorption spectra of neutral complexes (104 – 107, 111) in EtOH/MeOH at 295 K and 85 K.   141  Figure 5-7.  UV-vis absorption spectra of cationic complexes (108 – 110, 112) in EtOH/MeOH at 295 K and 85 K.  None of the complexes were emissive at either room temperature or 85 K.  Therefore, to further investigate the electronic structure of [Ru(P2T3)(2,2'-bpy)Cl][PF6], its transient absorption spectrum was obtained in CH3CN solution (Figure 5-8 (a)).  [Ru(P2T3)(2,2'- bpy)Cl][PF6] was easily purified and is soluble in CH3CN, which made it ideal for the transient absorption study.  In addition, [Ru(P2T3)(2,2'-bpy)Cl][PF6] has the most potential for use in a DSSC.   Replacing 2,2'-bpy with 4,4'-dicarboxyl-2,2'-bipyridine, would allow the complex to be attached to TiO2 in a DSSC.  Ru(2,2'-bpy) derivatives also generally perform better than their Ru(tpy) counterparts because 2,2'-bpy maintains ideal bond lengths and angles for an octahedral geometry around Ru(II).211  142 Excitation with a laser pulse resulted in a transient absorption band at 475 nm and no bleach was observed from 385-423 nm for [Ru(P2T3)(2,2'-bpy)Cl][PF6].  The absence of a bleach may be a result of a cancelling effect from transients that absorb at these wavelengths. [Ru(2,2'- bpy)3] 2+ has a transient at ~360 nm attributed to a transition on the reduced 2,2'-bpy242 and a similar 2,2'-bpy localized transition may occur on [Ru(P2T3)(2,2'-bpy)Cl][PF6] in the excited state. The transient at 475 nm is lower in energy than the triplet transient of terthiophene (450 nm)188 and higher than the transient of oxidized terthiophene (545 nm).243  Since the transient absorption observed for [Ru(P2T3)(2,2'-bpy)Cl][PF6] is in the range typically observed for terthiophene holes, the transient absorption observed here may be related to an excited state hole on the terthiophene.  The lifetime of the 475 nm transient absorption band in [Ru(P2T3)(2,2'- bpy)Cl][PF6] is 108 ± 1 ns (Figure 5-8), which is shorter than expected for a triplet species, but typical of charge transfer state such as in [Ru(2,2'-bpy)(tpy)Cl]+ that has an emission lifetime of 110 ns in CH3CN 244 and N3 (Chapter 2 (37), N719 protonated), which has an emission lifetime of 50 ns.84 The ground state absorption before and after transient absorption was identical, indicating photo-decomposition was negligible during the experiment.  143   Figure 5-8.  a) Transient absorption of [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109) in CH3CN and b) fit of decay of band at 507 nm.   144 Section 5.3.4 – Five Coordinate Ru(II) Species  When Ru(P2T3)Cl2(DMSO) and Ru(P2T3)Cl2(CH3CN) were dissolved in non-donating solvents, such as CH2Cl2, CHCl3, THF and DMF, they changed in colour from orange to green. The absorption spectrum of the green solutions had a band at 729 nm in CH2Cl2 for both Ru(P2T3)Cl2(DMSO) and Ru(P2T3)Cl2(CH3CN) (Figure 5-9).  Ru(P2T3)Cl2(DMSO) immediately began changing colour in CH2Cl2, whereas Ru(P2T3)Cl2(CH3CN) gradually changed colour overnight in CH2Cl2.  Similarly, in Ru(P2T5)Cl2(DMSO) a band appears at 729 nm in CH2Cl2. None of the cationic complexes showed a dramatic colour change in any solvent.  Figure 5-9.  Ru(P2T3)Cl2(DMSO) (104) and Ru(P2T3)Cl2(CH3CN) (105) spectra after being in CH2Cl2 overnight with the new band at 729 nm.   To elucidate the species responsible for the green colour change, the absorption and NMR spectra of Ru(P2T3)Cl2(DMSO) were monitored over several hours.  The absorption band at 729 nm in CH2Cl2 increased in intensity at a rate of ~0.006 min -1.  The peak in the 31P{1H} NMR spectrum at 1.54 ppm in CDCl3 disappeared over several hours as the solution became green.  No broadening was apparent in the baseline and no new peaks were observed, possibly because of different five-coordinate isomers in solution.  Likewise, the 1H NMR spectra in  145 CDCl3 did not show any peak broadening with time, which suggests that a diamagnetic species is responsible for the colour change. The aromatic region of the 1H NMR spectra became increasingly complicated with time.  The peak due to coordinated DMSO at 1.79 ppm decreased in intensity over time.  Concurrently, the peak due to free DMSO at 2.62 ppm245 increased in relative intensity (Figure 5-10).  This change in the NMR peak intensities occurred at ~0.004 min-1, the same order of magnitude as the rate of appearance of the 729 nm band in the absorption spectrum.  Figure 5-10.  1H NMR spectra showing the appearance of DMSO and disappearance of DMSO- Ru monitored with time in CDCl3.   Together the electronic absorption and 1H NMR spectra suggest that the DMSO coordinated to the Ru(II) dissociates to give a green 5-coordinate species, Ru(P2T3)Cl2, in non- donating solvents (Scheme 5-5).  Other five-coordinate diphosphino-Ru(II) complexes have also been reported as green coloured.  For example, Ru(dpb)Cl2 (dpb = 1,4- bis(diphenylphosphino)butane) is pale green246 and RuCl2(HPNP tBu) (HPNPtBu = HN(CH2CH2P(t-Bu2))2) is turquoise. 247 Ru(II) complexes also have a tendency to undergo dissociative reactions.248 To further determine whether the green solutions were due to Ru(P2T3)Cl2, a green CH2Cl2 solution was evaporated and the residue dissolved in DMSO.  Overnight, the solution  146 changed from green to orange.  This supports the conclusion that the green species is Ru(P2T3)Cl2 that coordinates DMSO, resulting in reformation of orange Ru(P2T3)Cl2(DMSO).  Scheme 5-5.    Section 5.3.5 – Electrochemistry  The ligand influence on the electrochemical oxidation potentials of a Ru(II) centre has been correlated to the observed Ru(III/II) oxidation potential (Eobs) for several common ligands, to give a ligand electrochemical parameter (EL) (Equation 5-1 in V vs NHE). 249 The EL value of a particular ligand reflects the electron density that it donates to the metal centre to which it is coordinated.249 This depends on the charge, σ-donating, π-donating, and π-accepting ability of the ligand.249 Lower EL values indicate more electron density is donated to the metal centre and therefore the metal is more easily reduced.249 Several other metals have also been correlated to EL values in equations similar to Equation 5-1. 249  EL values have been determined for several of the ligands used in the Ru(II) complexes synthesized here; specifically Cl- (-0.24 V), DMSO (0.47 V), CH3CN (0.34 V), 4,4'-bpy (0.27 V), 2,2'-bpy (0.259 V) and tpy (0.25 V). 249  Equation 5-1. Ref.249 04.0][97.0 +∑= Lobs EE    147 All of the Ru(II) complexes synthesized here have P2T3 bound to the Ru(II) centre in a tridentate manner, allowing determination of the EL for P2T3 (EP2T3).  Whether EP2T3 depends on the Ru-thiophene bond length or Ru-thiophene angle (Figure 5-11), both known to influence metal-thienyl π-back-bonding,250 is of interest.  To better understand the electronic effect of P2T3 and P2T5 on Ru(II), the CVs of the complexes were obtained in CH2Cl2 for the neutral complexes (104 – 107, 111) and CH3CN for the cationic complexes (108 – 110, 112) (Table 5-5).   Figure 5-11.  The angle (θ) between Ru and a coordinated thiophene ring.  The Ru(III/II) oxidation waves for the neutral complexes were consistent with the trend predicted from the EL values of CH3CN, DMSO, and 4,4'-bpy (Figure 5-12).  Oxidation of the P2T3 ligand was not observed for Ru(P2T3)Cl2(DMSO), Ru(P2T3)Cl2(CH3CN), Ru(P2T3)Cl2(4,4'- bpy), and [Ru(P2T3)Cl2(N-Me-4,4'-bpy)][I].  Increasing the conjugation length in Ru(P2T5)Cl2(DMSO) resulted in a decrease in the oxidation potential of the oligothiophene, with an oxidation wave at 1.48 V (Figure 5-12 (a)). The cationic Ru(II) complexes (108 - 110) had Ru(III/II) oxidation waves anodically shifted from the neutral complexes, as predicted by the larger EL values of the ancillary ligands (Figure 5-13).  The Ru(III/II) oxidation wave was difficult to differentiate from the ligand-based oxidation since they occurred at similar potentials.  [Ru(P2T3)(CH3CN)2Cl][PF6], [Ru(P2T3)(2,2'- bpy)Cl][PF6] and [Ru(P2T3)(tpy)][PF6]2 all have an irreversible oxidation wave at ~1.7 V, which suggested a common moiety was oxidized at this potential.  Additionally, ADF-DFT calculations by Dr. Jeffrey Nagle were used to help assign the oxidation waves. For [Ru(P2T3)(2,2'- bpy)Cl][PF6], these calculations suggested that the HOMO was localized on the Ru and the HOMO+1 was localized on P2T3.  For [Ru(P2T3)(tpy)][PF6]2 on the other hand, the DFT calculations indicated that the HOMO was localized on the P2T3 and the HOMO+1 was localized on the Ru.  From this, it was concluded that the common oxidation wave at ~1.7 V was P2T3 based while the oxidation wave at 1.24 V, 1.93 V, and 2.08 V is due to the Ru(III/II) oxidation for [Ru(P2T3)(2,2'-bpy)Cl][PF6], [Ru(P2T3)(tpy)][PF6]2 and [Ru(P2T3)(CH3CN)3Cl][PF6], respectively.  148  Figure 5-12.  a) CV of Ru(P2T3)Cl2(DMSO) (104) and Ru(P2T5)Cl2(DMSO) (111), and b) CV of Ru(P2T3)Cl2(CH3CN) (105), Ru(P2T3)Cl2(4,4'-bpy) (106) and [Ru(P2T3)Cl2(N-Me-4,4'-bpy)][I] (107) on a Pt disk electrode (scan rate = 100 mV/s).  Electrolyte = 0.1 M [n-Bu4N][PF6].  Solvent = CH2Cl2.   149   Figure 5-13.  CVs of [Ru(P2T3)(CH3CN)2Cl][PF6] (108), [Ru(P2T3)(tpy)][PF6]2 (110), and [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109) on a Pt disk electrode (scan rate = 100 mV/s).  Electrolyte = 0.1 M [n-Bu4N][PF6].  Solvent = CH3CN.  150  Table 5-5.  Oxidation potentials of Ru(II) complexes. Compound Ru(III/II) /V vs. SCE (∆E / mV) Ligand+/0/ V vs. SCE EP2T3/ V vs. NHE [Ru(P2T3)(CH3CN)2Cl][PF6] a (108) 2.08c 1.72c 1.91 [Ru(P2T3)(2,2'-bpy)Cl][PF6] a  (109) 1.24 c 1.76c 1.46 [Ru(P2T3)(tpy)][PF6]2 a  (110) 1.93 c 1.73c 1.95 [Ru(P2T3)(N-Me, 4,4'-bpy)Cl2][I] b  (107) 1.29 c - N/A Ru(P2T3)(4,4'-bpy)Cl2 b  (106) 1.08 (70 mV) - 1.53 Ru(P2T3)Cl2(CH3CN) b (105) 0.77 (45 mV)  - 1.15 Ru(P2T3)Cl2(DMSO) b (104) 1.17c - 1.42 Ru(P2T5)Cl2(DMSO) b (111) 1.19c 1.48c 1.46 [Ru(P2T5)(tpy)][PF6]2 a (112) N/A 1.20, 1.28 - a Recorded in CH3CN with 0.1 M [n-Bu4N][PF6]. b Recorded in CH2Cl2 with 0.1 M [n- Bu4N][PF6]. cIrreversible oxidation wave, Ep.  The Ru(III/II) oxidation potentials varied between 0.77 V to 2.08 V for all the complexes.  Using Equation 5-1 and known EL values for the other ligands, EP2T3 was determined where possible (Table 5-5).  This value varied from 1.15 V to 1.95 V between the complexes.  In order to determine whether this difference could be related to the Ru-S bond length, EP2T3 vs the Ru-S bond length was plotted for Ru(P2T3)Cl2(CH3CN), [Ru(P2T3)(2,2'- bpy)Cl][PF6] and [Ru(P2T3)(tpy)][PF6]2 (Figure 5-14).  For the three points, there is a linear relationship between the Ru-S distance and EP2T3.  No correlation is found between the Ru- thiophene angle and EP2T3.  Overall, the proximity of the central thiophene to Ru(II) dramatically influences the observed Ru(II) oxidation potential.  This suggests that the closer the thienyl-S is to the metal centre, the lower the observed oxidation potential of the Ru(II).   151  Figure 5-14.  Graph correlating EP2T3 with Ru-S bond length for Ru(P2T3)Cl2(CH3CN) (105), [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109) and [Ru(P2T3)(tpy)][PF6]2 (110).  [Ru(P2T3)(2,2'-bpy)Cl][PF6] has two reduction waves: an irreversible wave at –1.38 V and a quasi-reversible wave at –1.57 V (Table 5-6).  Similarly, [Ru(P2T3)(tpy)][PF6]2 also has two reduction waves: an irreversible wave at –1.35 V and a quasi-reversible wave at –1.67 V. [Ru(P2T3)(CH3CN)2Cl][PF6] has a single irreversible reduction wave at –1.49 V.    To probe the nature of the reduction waves, the difference between the ligand oxidation potential and the irreversible reduction waves of [Ru(P2T3)(2,2'-bpy)Cl][PF6], [Ru(P2T3)(tpy)][PF6]2 and [Ru(P2T3)(CH3CN)2Cl][PF6] was calculated.  The calculated differences were between 3.08 eV (403 nm) to 3.21 eV (386 nm).  This value is similar to the energy of the π π∗ transition in the absorption spectra of the complexes, so the irreversible reduction wave may be due to reduction of the terthiophene backbone of P2T3. The quasi-reversible waves of [Ru(P2T3)(2,2'-bpy)Cl][PF6] and [Ru(P2T3)(tpy)][PF6]2 are assigned to reduction of the polypyridine ligands.  Similarly, [Ru(PT3-P,S)(2,2'-bpy)] 2+ has a reduction wave at –1.28 V vs SCE,94  [Ru(2,2'-bpy)3] 2+ has a reduction wave at –1.36 V vs SCE251 ([Ru(2,2'-bpy)3] 2+ is also reported to have two reduction waves at –1.73 V and –1.98 V vs Fc/Fc+252) and [Ru(tpy)2] 2+ has reduction waves at –1.66 V and –1.96 V vs Fc/Fc+.252  152  Table 5-6.  Reduction waves of neutral Ru(P2T3) complexes (108 – 110). a  Complex E1/2, red/ V vs SCE (∆E/mV) Assignment P2T3 +/0 – P2T3 0/-/V (/nm) [Ru(P2T3)(CH3CN)2Cl][PF6] (108) -1.49b P2T3 0/- 3.21 (386) [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109) -1.57 (110) 2,2'-bpy0/- - [Ru(P2T3)(2,2'-bpy)Cl][PF6] (109) -1.38b P2T3 0/- 3.12 (395) [Ru(P2T3)(tpy)][PF6]2 (110) -1.67 (100) tpy 0/- - [Ru(P2T3)(tpy)][PF6]2 (110) -1.35 b P2T3 0/- 3.08 (403) a Measurements carried out in CH3CN with 0.1 M [n-Bu4N][PF6]. bIrreversible wave, Ep.   None of the neutral or cationic Ru(P2T3) complexes electrochemically polymerized.  The steric bulk imposed by the diphenylphosphine groups could prevent the complexes from oxidatively coupling at the terminal α-positions of the P2T3 backbone.  Using P2T5 rather than P2T3 should decrease the steric bulk near the α-position of the terminal thiophenes and result in a decrease in the oxidation potential of the oligothiophene, which could encourage electrochemical polymerization.  Ru(P2T5)Cl2(DMSO) and [Ru(P2T5)(tpy)][PF6]2 were both synthesized for comparison.  Ru(P2T5)Cl2(DMSO) and [Ru(P2T5)(tpy)][PF6]2 both had oligothiophene oxidation waves at a lower potential than Ru(P2T3)Cl2(DMSO) and [Ru(P2T3)(tpy)][PF6]2 respectively (Table 5-5), but increasing the number of scans did not yield increased conductivity.  Therefore, no conducting material was deposited on the electrode.  The lack of polymerization could be a result of the spin density not being localized on the terminal α-position of the oligothiophene upon oxidation.    153 Section 5.4 – Conclusions   Several neutral halogenated Ru(II) complexes were synthesized: Ru(P2T3)Cl2(DMSO), Ru(P2T3)Cl2(CH3CN), Ru(P2T3)Cl2(4,4'-bpy), [Ru(P2T3)Cl2(N-Me-4,4'-bpy)][I] and Ru(P2T5)Cl2(DMSO).  For comparison, several cationic dehalogenated Ru(II) complexes were also synthesized: [Ru(P2T3)Cl(CH3CN)][PF6], [Ru(P2T3)(2,2'-bpy)Cl][PF6], [Ru(P2T3)(tpy)][PF6]2, and [Ru(P2T5)(tpy)][PF6]2.    The crystal structures obtained show that P2T3 bonds as a tridentate ligand to Ru(II).  For both the halogenated and dehalogenated complexes, the electronic spectra were dominated by ππ* transitions.  [Ru(P2T3)(2,2'- bpy)Cl][PF6] and [Ru(P2T3)(tpy)][PF6] had charge transfer bands in their spectra in addition to the ππ* transitions.  At low temperature, the electronic spectra of the neutral complexes and [Ru(P2T3)(CH3CN)2Cl][PF6] separated into two bands as a result of vibronic coupling or resolution of isomer bands.  Similarly, [(Ru(P2T3)(2,2'-bpy)Cl][PF6], [Ru(P2T3)(tpy)][PF6]2 and [Ru(P2T5)(tpy)][PF6]2 had shoulders resolve at 85 K typical of vibronic coupling with oligothiophenes or polypyridines.  All of the Ru(II) complexes were non-emissive at room temperature and low temperature.  The transient absorption spectrum of [Ru(P2T3)(2,2'- bpy)Cl][PF6] was taken as a representation of the other complexes and its excited state has a lifetime of ~100 ns.  This lifetime is comparable to that of dyes used in DSSCs.  Interestingly, Ru(P2T3)Cl2(DMSO), Ru(P2T3)Cl2(CH3CN) and Ru(P2T5)Cl2(DMSO) all show a band at 729 nm when left dissolved in non-coordinating solvents.  This green colour is possibly a result of a five- coordinate Ru(II) complex forming in solution.  The cationic species, by contrast, were stable for at least two days in non-coordinating solvents.  The cyclic voltammograms of all the complexes were obtained.  For the P2T3 complexes, the EP2T3 was determined and found to depend on the Ru-S bond length.  The increased conjugation in Ru(P2T5)Cl2(DMSO) and [Ru(P2T5)(tpy)][PF6]2 resulted in a lowering of the oxidation potential of the oligothiophene, but this did not enable electropolymerization of a Ru(II) complex.   154 CHAPTER 6 CONCLUSIONS AND FUTURE WORK  Section 6.1 – Conclusions   As set out in the goals, this thesis investigated the effect of β-substituents on oligothiophenes and the compounds’ resulting properties.  Terthiophene was derivatized with aryl-phosphines (P2T3) and acetylenes (A2T3), while pentathiophene was derivatized with aryl phosphines (P2T3).  P2T3 was used to coordinate two Au(I) atoms or one Ru(II) atom to result in Type II metal-thienyl complexes. The ability of the bis-phosphine ligand to be an effective bridge with Au(I) or chelate with Ru(II) demonstrated the versatility of this motif.  The effect of increasing the conjugation and decreasing the steric bulk around the metal centre was probed by using A2T3 rather than P2T3 to bridge two Au(I) atoms.  In the Ru(II) complexes, the conjugation was increased using P2T5.  Differences in the π-conjugation were probed by absorption, emission and electrochemical measurements for P2T3 (57), P2T5 (58) and A2T3 (59) in Chapter 2.  P2T3 has reduced conjugation when compared to unsubstituted terthiophene, A2T3 or P2T5.  A2T3 was more planar in the solid-state, and its absorption and emission bands lower in energy than the corresponding bands in P2T3.  Similarly, the absorption and emission bands of P2T5 were red- shifted relative to both derivatized terthiophenes. The mechanical influence on conjugation was probed by grinding P2T3 in the solid-state.  Grinding P2T3 caused a temporary hypsochromic shift in the absorption and emission bands, attributed to a decrease in the planarity of the terthiophene.  P2T3 and P2T5 both showed an oligothiophene-based oxidation wave, but neither electrochemically polymerized. In contrast, A2T3 electrochemically polymerized into an electrochromic film.  Together, these results show that both the substituents and the conjugation length influences the properties of the oligothiophenes.  In Chapter 3, P2T3 bridged two Au(I) centres and this complex was compared with PT3- Au(I) complexes.  Despite the lack of aurophilic interactions in the solid-state, coordination of Au(I) influenced the backbone conjugation by causing twisting along the terthiophene backbone of all the complexes.  For (AuCl)2P2T3 (80), unlike the PT3 complexes, this effect was persistent in solution as evident from the absorption spectrum that was significantly blue-shifted from the  155 free ligand.  Mechanical influences on the conjugation of (AuCl)2P2T3 were probed with grinding.  Grinding (AuCl)2P2T3 caused a red-shift in the absorption band, which concurrently caused the non-emissive microcrystalline powder to emit from a ligand-based state when irradiated.  The red-shift in the absorption band is likely a result of an increase in planarity elicited by grinding that coincides with a reduction in radiationless decay pathways in the powder, opposite of the behaviour of uncoordinated bis-phosphino-terthiophene.  Chapter 4 investigated A2T3 as a bridge for two Au(I) ions.  Three bis-Au(I)-A2T3 complexes were synthesized with a triphenylphosphine, cyanide and a bridging bis(diphenylphosphino)methane as other ligands.  As with the Au(I)-phosphine complexes, conjugation of the terthiophene backbone in (AuPPh3)2A2T3 (93) and [n-Bu4N]2[(AuCN)2A2T3] (94) was decreased and no aurophilic interactions were present.  Using dppm as a bridging ligand in conjunction with the A2T3 bridge caused an aurophilic interaction and also resulted in an increase in the planarity of the terthiophene backbone.  Coordination of Au(I) red-shifted the ππ* bands of the absorption spectra for all the acetylide complexes, unlike the hypsochromic shift observed in the Au(I)-phosphino-terthiophene complexes’ ππ* bands in Chapter 3.  The red-shift of the acetylide complexes was sensitive to the other ligands on the Au(I) ions, which showed the coordinated Au(I) has an electronic and structural effect on the oligothiophene.  Only the complex with an aurophilic interaction was non-emissive at room temperature.  In EtOH/MeOH glasses the Au(I)-acetylide complexes all have vibronic coupling in the absorption and emission spectra, similar to A2T3.  All of the acetylide complexes are capable of photo- reducing MV2+, but only (AuPPh3)A2T3 (93) and Au2(dppm)A2T3 (95) showed excited-state electron transfer.  The acetylide complexes also electropolymerized.  The Au-Au interaction in the dppm complex was persistent in solution as evident by a Au(I/II) oxidation wave and the polymerized material had a similar oxidation wave.  Overall, the complexes in Chapter 3 and Chapter 4 show that the donor group used to tether the metal ion to terthiophene influences the resulting properties of the complexes that is related to the conjugation and metal-metal interactions.  Lastly, in Chapter 5, P2T3 and P2T5 were used as tridentate ligands for a series of neutral (104 – 107, 111) and cationic (108 – 110, 112) Ru(II) centres.  The tridentate coordination was confirmed via solid-state molecular structures for three of the Ru(II) complexes (105, 109, and 110).  The absorption spectra of all the complexes were dominated by ππ* transitions.  These transitions are red-shifted from the comparable transitions in P2T3 because the Ru(II) centre  156 donates electron density to the terthiophene backbone and/or increased rigidity of the oligothiophene backbone.  With P2T5, a red-shift in the lowest energy absorption bands were observed when compared to the P2T3-Ru(II) complexes, consistent with the increased conjugation from additional thienyl groups observed from the absorption spectra in Chapter 2. For the [Ru(P2T3)(2,2'-bpy)Cl][PF6], a transient absorption was observed with a lifetime of ~100 ns, long enough to be useful in DSSCs.  Ru(P2T3)Cl2(DMSO) (104), Ru(P2T3)Cl2(CH3CN) (105), Ru(P2T5)Cl2(DMSO) (112) were unstable in non-coordinating solvent and formed five- coordinate species when left in solution.  The electrochemistry of all the complexes had Ru(II/III) oxidation waves, which for 104 – 106 and 108 – 110  was used to determine EP2T3. The value of EP2T3 depended on the Ru(II)-thiophene distance.  The cationic complexes (108 – 110, 112) and Ru(P2T5)Cl2(DMSO) (111) all had an oligothiophene oxidation wave, but none of these complexes could be electrochemically polymerized.  The contrast of the properties of the Au(I)-phosphine complexes in Chapter 3 and Ru(II)-phosphine complexes in Chapter 5 show that the type of metal coordinated to a phosphino-oligothiophene can alter the photophysical properties.  Overall, new β-substituted phosphino- and ethynyl- oligothiophenes were synthesized and characterized.  These were coordinated to Au(I) and Ru(II) to result in Type II materials. The resulting properties of the compounds depended on the electronic and steric effects modulated with the chosen donating group on the oligothiophene, the conjugation length and the metal ion coordinated to the oligothiophene.  Section 6.2 – Future Work   The investigations in this thesis could be extended in various directions.  Using alternate donating groups such as thiols or amines, rather than aryl phosphines and ethynyl groups, on the oligothiophene could significantly alter the properties since these donating groups have different electronic and steric effects.  Coordination of these ligands to metal ions could result in complexes with different metal-thiophene interactions and photophysical properties.  Additionally, other metals could coordinate with the bis-ethynyl and bis-phosphino- oligothiophenes.  For example, Ag(I) complexes can be analogous to Au(I) complexes with  157 argentophilic interactions and sometimes a linear coordination geometry.253,254 Whether Ag(I) would coordinate to P2T3 in an analogous manner to the Au(I) complex and cause changes in the structure of the terthiophene backbone would be worth investigating.  It would also be interesting to see whether P2T3 and P2T5 are also effective tridentate ligands for d 8 metal ions such as Pt(II).  Pt(II), Cu(I) and Ag(I)  have potentially interesting photophysical properties and unique structures when coordinated to ethynyl groups,255 and hence their coordination to the bis-ethynyl terthiophene system could be interesting.  Mixed metal complexes could also potentially be useful, such as a Au(I)-Pt(II) complex.  Previous bridged Au(I)-Pt(II)-phosphine systems can be chemically oxidized to Au(II)-Pt(III) then photoreduced back to a Au(I)-Pt(II) system256 which is useful for hydrogen generation.  Since the ethynyl complexes with the Au(I)-Au(I) interaction had a Au(II/I) oxidation wave in the CV, mixed metal centres may also be oxidizable.  Finally, the ethynyl-Au(I) project could be extended by using the Au2A2T3 framework as an antenna for an emissive compound.  There are also additional possibilities for the Ru(II)-phosphino-oligothiophene project. Since the Ru(II)-2,2'-bpy  complex had a charge separated lifetime comparable to dyes in photovoltaic cells, it would be worth changing the 2,2'-bpy to a 4,4'-dicarboxyl-2,2'-bpy. These carboxyl-substituted molecules could be adsorbed to a metal-oxide anode, such as TiO2 on ITO coated glass.  Immersing the dye coated metal oxide into a solution with an appropriate reducing agent (e.g. I- or [Co(2,2´-bpy)3] 2+)  and addition of a cathode (e.g. Au of Pt) would result in a DSSC that could be tested.  Exchanging the chloride for other ligands, such as -SCN-, -CN- or pyridine could also be interesting since these substituents effect the excited state lifetime, performance in DSSCs, and emission.84 Altering the chelating polypyridines to include phenanthroline or substituted terpyridines could also influence the excited state.  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P2T3 A2T3 formula C36H26P2S3 C16H8S3 habit plate orange, blade dimensions/ mm 0.03 × 0.18 × 0.25 0.05 × 0.15 × 0.55 temperature/ K 173.2(1) 296.0(1) cryst syst triclinic monoclinic space group P –1  P 21/n a/ Å 9.3829(7) 10.976(3) b/ Å 11.5838(9) 5.5313(16) c/ Å 14.4954(12) 23.015(7) α/ ° 89.673(4) 90 β/ ° 72.855(4) 98.154(8) γ/ ° 80.512(4) 90 V/ Å3 1483.4(2) 3178.6(2) Z 2 4 ρcalc/ g cm -1 1.381 1.423 µ (Mo Κα)/ cm-1 3.84 5.16 Ra (I > 2.0σ(I)) 0.0462 0.0364 Rw a (I > 2.0σ(I)) 0.0920 0.0833 goodness of fit 1.00 1.059 aFunction minimized Σw(|Fo| - |Fc|) 2 R = Σ||Fo| - |Fc|| / Σ|Fo|, Rw = [Σw(|Fo| - |Fc|) 2 / Σw|Fo| 2]1/2.   173   Table A1-2.  Selected crystal structure data for AuClPT3 (76), AuSPhPT3 (77) and AuSC6F5PT3 (78).  AuClPT3 AuSPhPT3 AuSC6F5PT3 formula C24H17AuClPS3 C30H22AuPS4 C30H17AuF5PS4 habit - - colourless, irregular dimensions/ mm 0.33 × 0.22 × 0.04 0.35 × 0.29 × 0.14 0.25 × 0.25 × 0.20 temperature/ K 293 293 173(2) cryst syst triclinic triclinic triclinic space group P –1 P –1 P –1 a/ Å 9.0528(15) 10.392(4) 9.0923(13) b/ Å 11.0740(22) 11.197(4) 12.0861(17) c/ Å 12.0991(22) 14.252(4) 13.2603(17) α/ ° 77.376(15) 74.51(3) 96.624(7) β/ ° 86.044(14) 73.81(3) 93.529(7) γ/ ° 87.787(14) 66.44(3) 100.958(8) V/ Å3 1180.5(4) 1436.8(9) 1415.8(3) Z 2 2 2 ρcalc/ g cm -1 1.871 1.707 1.944 µ (Mo Κα)/ cm-1 66.6 54.6 56.01 Ra,b  0.032 0.035 0.0248 Rw a,b  0.040 0.041 0.0576 goodness of fit 0.94 1.20 1.027 aFunction minimized Σw(|Fo| - |Fc|) 2 R = Σ||Fo| - |Fc|| / Σ|Fo|, Rw = [Σw(|Fo| - |Fc|) 2 / Σw|Fo| 2]1/2. b I > 2.5σ(I) for AuClPT3 and AuSPhPT3 and I > 2.0σ(I) for AuSC6F5PT3.   174  Table A1-3.  Selected crystal structure data for (AuCl)2P2T3 (80) and (AuCN)2P2T3 (82).  (AuCl)2P2T3·CH2Cl2 (AuCN)2P2T3·2CH2Cl2 formula C37H28Au2Cl4P2S3 C40H30Au2Cl4N2P2S3 habit plate colourless, irregular dimensions/ mm 0.015 × 0.20 × 0.30 0.20 × 0.18 × 0.12 temperature/ K 113(2) 173(2) cryst syst monoclinic triclinic space group P 21/c P –1 a/ Å 9.6976(2) 10.5862(7) b/ Å 28.8439(6) 13.5751(11) c/ Å 27.6767(6) 15.8078(13) α/ ° 90 103.897(3) β/ ° 97.3710(10) 100.820(3) γ/ ° 90 96.212(3) V/ Å3 7677.7(3) 2137.8(3) Z 8 2 ρcalc/ g cm -1 2.018 1.915 µ (Mo Κα)/ cm-1 81.87 73.58 Ra (I > 2.0σ(I)) 0.0715 0.0311 Rw a (I > 2.0σ(I)) 0.0669 0.0713 goodness of fit 1.15 1.031 a Function minimized Σw(|Fo| - |Fc|) 2  R = Σ||Fo| - |Fc|| / Σ|Fo|, Rw = [Σw(|Fo| - |Fc|) 2  / Σw|Fo| 2 ] 1/2 .    175  Figure A1-1.  Solid-state molecular structure of the second (AuCl)2P2T3·CH2Cl2 (80) molecule in the unit cell.  Hydrogen atoms and occluded CH2Cl2 are omitted for clarity and thermal ellipsoids are drawn at 50% probability. Table A1-4.  Selected bond lengths and angles for the second molecule of (AuCl)2P2T3·CH2Cl2 (80) in the unit cell. Bond Lengths (Å) Au3-Cl3  2.289(3) Au4-Cl4 2.287(3) Au3-P3 2.220(3) Au4-P4 2.229(3) P3-C15  1.800(11) P3-C49 1.801(11) P3-C55 1.814(11) P4-C22 1.795(12) P4-C61 1.797(12) P4-C67 1.808(11) S6-C21 1.719(11) S6-C24 1.703(15) C21-C22 1.378(15) C22-C23 1.443(16) C23-C24 1.367(17) C20-C21 1.494(12) Angles (º) Cl3-Au3-P3 177.22(13) Cl4-Au4-P4 178.85(12) Au4-P4-C22 111.3(4) Au4-P4-C61 114.9(4) C22-P4-C61 104.4(5) Au4-P4-C67 114.1(4) C22-P4-C67 106.2(5) C61-P4-C67 105.0(5) C21-S6-C24 91.5(6) C23-C24-S6 112.5(9) C22-C23-C24 112.7(11) C21-C22-C23 110.4(10) S6-C21-C22 112.8(8) P4-C22-C23 125.5(9) P4-C22-C21 123.7(8) Torsion Angles (º) S4-C16-C17-S5 51(1) S5-C20-C21-S6 50.3(9)  176 Table A1-5.  Selected crystal structure data for (AuPPh3)A2T3 (93), [n-Bu4N][(AuCN)2A2T3] (94) and Au2dppmA2T3 (95).  (AuPPh3)2A2T3 [n-Bu4N]2[(AuCN)2A2T3] Au2(dppm)(A2T3)·(CH3)2CO formula C52H36Au2P2S3 C50H78N4S3Au2 C44H28OP2S3Au habit yellow, plate yellow, plate orange, plate dimensions/ mm 0.05 × 0.10 × 0.18 0.12 × 0.50 × 0.60 0.08 × 0.33 × 0.45 temperature/ K 173(2) 173(2) 103.0(1) cryst syst monoclinic monoclinic monoclinic space group C 2/c  P 21/n  P 21/c a/ Å 14.6679(15) 19.4758(14) 12.3125(4) b/ Å 22.881(2) 13.1860(9) 12.9082(4) c/ Å 14.2426(15) 20.7761(13) 24.6631(9) α/ ° 90 90 90 β/ ° 96.333(5) 101.691(3) 93.101(2) γ/ ° 90 90 90 V/ Å3 4750.9(8) 5224.8(6) 3914.02(5) Z 4 4 4 ρcalc/ g cm -1 1.696 1.558 1.909 µ (Mo Κα)/ cm-1 64.02 57.65 77.64 Ra (I > 2.0σ(I)) 0.0218 0.0315 0.0258 Rw a (I > 2.0σ(I)) 0.0493 0.0621 0.0574 goodness of fit 1.026 1.018 1.035 aFunction minimized Σw(|Fo| - |Fc|) 2 R = Σ||Fo| - |Fc|| / Σ|Fo|, Rw = [Σw(|Fo| - |Fc|) 2 / Σw|Fo| 2]1/2.   177 Table A1-6.  Selected crystal structure data for Ru(P2T3)Cl2(CH3CN) (105), [Ru(P2T3)(2,2´- bpy)Cl][PF6] (109) and [Ru(P2T3)(tpy)][PF6] (110).  Ru(P2T3)Cl2(CH3CN) ·DMF [Ru(P2T3)(2,2´- bpy)Cl][PF6] [Ru(P2T3)(tpy)][PF6]·0.63 H2O formula C41H36Cl2N2OP2RuS3 C46H34ClF6N2P3RuS3 C51H38.25F12N3O0.63P4RuS3 habit orange, plate orange, irregular orange, needle dimensions/ mm  0.30 × 0.25 × 0.06 0.30 × 0.18 × 0.07 0.40 × 0.14 × 0.10 temperature/ K 173(2) 173(2) 173(2) cryst syst triclinic triclinic orthorhombic space group P 1 P –1 P b c a a/ Å 11.4316(11) 9.9549(13) 23.1585(18) b/ Å 12.3814(11) 14.7616(19) 17.9103(13) c/ Å 14.7724(14) 30.146(3) 24.1797(18) α/ ° 79.927(4) 97.643(5) 90.00 β/ ° 71.311(4) 92.318(5) 90.00 γ/ ° 79.022(4) 95.276(5) 90.00 V/ Å3 1929.7(3) 4365.8(9) 10029.2(13) Z 2 4 8 ρcalc/ g cm -1 1.554 1.604 1.659 µ (Mo Κα)/ cm-1 8.27 7.37 6.53 Ra (I > 2.0σ(I)) 0.0316 0.0463 0.0580 Rw a (I > 2.0σ(I)) 0.0735 0.0809 0.1149 goodness of fit 1.066 1.022 1.152 aFunction minimized Σw(|Fo| - |Fc|) 2 R = Σ||Fo| - |Fc|| / Σ|Fo|, Rw = [Σw(|Fo| - |Fc|) 2 / Σw|Fo| 2]1/2.   178  Figure A1-2.  Solid-state molecular structure of the second Ru(P2T3)Cl2(CH3CN)·DMF (105) molecule in the unit cell.  Hydrogen atoms and occluded CH2Cl2 are omitted for clarity and thermal ellipsoids are drawn at 50% probability. Table A1-7.  Selected bond lengths and angles for the second molecule of Ru(P2T3)Cl2(CH3CN)·DMF (105) in the unit cell. Bond Lengths (Å) P3-Ru2 2.3782(13) P4-Ru2 2.3686(13) S5-Ru2 2.2500(12) Cl3-Ru2 2.4003(12) Cl4-Ru2 2.4322(13) Ru2-N2 2.003(5) C43-S5 1.755(5) C46-S5 1.755(5) C43-C44 1.348(7) C44-C45 1.410(8) C45-C46 1.355(8) C46-C47 1.421(7) C41-P3 1.832(5) C48-P4 1.834(5) C75-N2 1.126(7) C75-C76 1.464(8) Angles (º) C43-S5-C46 92.5(3) C45-C46-S5 109.0(4) C46-C45-C44 114.2(5) C43-C44-C45 114.9(5) C44-C43-S5 108.8(4) C41-P3-Ru2 117.17(17) C51-P3-Ru2 112.00(16) C57-P3-Ru2 119.11(15) C48-P4-Ru2 116.98(17) C69-P4-Ru2 110.76(15) C63-P4-Ru2 119.67(16) P4-Ru2-P3 176.13(5) S5-Ru2-Cl3 178.71(5) N2-Ru2-Cl4 177.93(12) Torsion Angles (º) S5-C46-C47-S4 153.8(3) S6-C42-C43-S5 151.1(3)   179   Figure A1-3.  Solid-state molecular structure of the second [Ru(P2T3)(2,2´-bpy)Cl][PF6] (109) molecule in the unit cell.  Hydrogen atoms and [PF6] - counterion are omitted for clarity and thermal ellipsoids are drawn at 50% probability.  Table A1-8.  Selected bond lengths and angles for the second molecule of [Ru(P2T3)(2,2´- bpy)Cl][PF6] (109) in the unit cell.         Bond Lengths (Å) Ru2-P4 2.3720(10) Ru2-P3 2.4005(10) S5-Ru2 2.2915(12) N3-Ru2 2.071(3) N4-Ru2 2.063(3) Ru2-Cl2 2.4279(13) C54-S5 1.748(4) C51-S5 1.753(4) C51-C52 1.364(6) C52-C53 1.416(6) C53-C54 1.360(5) C54-C55 1.447(5) Angles (o) C54-S5-C51 92.48(19) C52-C51-S5 109.3(3) C51-C52-C53 113.6(4) C54-C53-C52 114.6(4) C53-C54-S5 109.1(3) C49-P3-Ru2 112.10(15) C75-P3-Ru2 110.96(11) C69-P3-Ru2 121.35(12) P4-Ru2-P3 174.41(3) N4-Ru2-Cl2 173.03(8) N3-Ru2-S5 175.22(8) Torsion Angles (o) S4-C50-C51-S5 133.5(3) S5-C54-C55-S6 171.7(2)

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