This dissertation, "Syntheses, Characterization and Photophysical Properties of Platinum(II) and Gold(I) Complexes Containing Ortho- and Meta-oligo(phenyleneethynylene) Ligands" by 朱明新, Mingxin, Zhu, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled SYNTHESES, CHARACTERIZATION AND PHOTOPHYSICAL PROPERTIES OF PLATINUM(II) AND GOLD(I) COMPLEXES CONTAINING ORTHO- AND META- OLIGO(PHENYLENEETHYNYLENE) LIGANDS Submitted by Zhu Mingxin for the degree of Doctor of Philosophy at The University of Hong Kong in March 2008 Metal complexes containing oligo(phenyleneethynylene) (PE) are of great importance in photophysics and material science. The syntheses, characterizations and photophysical properties of the light-emitting platinum(II) and gold(I) complexes with flexible ortho- and meta-PE and 2,5-diphenyl-1,3,4-oxadiazole ligands were described. Several novel dinuclear terpyridyl platinum(II) complexes with ortho-PE ligands were synthesized and their crystal structures were determined. The t t 2+ t platinum(II) complexes [( Bu tpy)Pt-(ortho-PE)-Pt( Bu tpy)] ( Bu tpy = 4,4′,4″-tri- 3 3 3 tert-butyl-2,2′ 6′,2″-terpyridine) adopted a helical conformation in their crystal structures, and their phosphorescence recorded in acetonitrile/water mixtures shifted to lower energy with enhanced intensity when the water content increased. A hydrophobic folding process was suggested for the complexes with long ortho-PE(n) (n >= 3), and the red-shifted and enhanced phosphorescence was attributed to inter- and intra-molecular π-π interactions. The mononuclear terpyridine and C DEGREESN DEGREESN capped t + platinum(II) complexes [( Bu tpy)Pt-(ortho-PE)] and [(C DEGREESN DEGREESN)Pt-(ortho-PE)] (HC DEGREESN DEGREESN = 6-phenyl-2,2′-bipyridine) were studied for comparison. A series of mononuclear and dinuclear ortho- and meta-PE gold(I) complexes, [(PCy )Au-(ortho-PE)] (PCy = tricyclohexylphosphine), [(PCy )Au-(ortho-PE)- 3 3 3 Au(PCy)], [(PCy )Au-(meta-PE)] and [(PCy )Au-(meta-PE)-Au(PCy)] were 3 3 3 3 synthesized to examine the effect of ortho- and meta-conjugation. A ππ* emission of the PE ligands was switched on at room temperature by the attachment of [Au(PCy )] fragment due to the heavy atom effect. The delayed fluorescence from the ππ* excited states of the PE ligands was observed, and a triplet-triplet annihilation pathway was proposed. The difference in conjugation of para-, ortho- and meta-PE ligation was examined by comparison of the singlet and triplet emission energies of the gold(I) complexes. By extrapolating the plot of the emission energy against the PE chain length in the complex, the triplet emission energies of poly(ortho-PE) and poly(meta-PE) were estimated to be 530 and 470 nm respectively. These complexes together with the reported [Au(PCy )] complexes containing para-PE ligands, constitute a complete class of [Au(PCy )] supported phenyleneethynylene complexes. 2+ New ortho-PE ligands were used as flexible linkers for [Pt(PEt ) ] moieties 3 2 (PEt = triethylphosphine). Three neutral platinum(II) macrocycles with the maximum ring size of 60 atoms were synthesized and their crystal structures were determined, 31 revealing decreased nuclearity when the ortho-PE length increases. The P NMR spectra of [Pt(PEt ) {ortho-PE(5)}] with a rigid conformation at various temperatures 3 2 are consistent with the calculated spectrum of ABX spin system. A series of platinum(II)-bis(triethylphosphine) complexes containing 2,5- diphenyl-1,3,4-oxadiazole moiety were synthesized, and