This dissertation, "Novel Luminescent Cyclometalated Gold (III) Alkynyls: Design, Synthesis, Photophysics and Their Multinuclear Assemblies" by Ling-ling, Hung, 熊靈玲, 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 NOVEL LUMINESCENT CYCLOMETALATED GOLD(III) ALKYNYLS - DESIGN, SYNTHESIS, PHOTOPHYSICS AND THEIR MULTINUCLEAR ASSEMBLIES Submitted by HUNG Ling Ling for the Degree of Doctor of Philosophy at The University of Hong Kong in November 2007 A new class of luminescent mononuclear cyclometalated gold(III) complexes containing various monoynyl ligands, [Au(RC DEGREESN(R′) DEGREESCR)(C≡CR′′)], i.e. [Au(C DEGREESN DEGREESC)(C≡CR′′)] (HC DEGREESN DEGREESCH = 2,6-diphenylpyridine; R′′ = C H, C H-Cl-p, 6 5 6 4 C H-C H -p, C H-OCH -p, C H-NO -p, C H-NH -p, C H-N(CH ) -p, 6 4 6 13 6 4 3 6 4 2 6 4 2 6 4 3 2 t t t t C H-N(C H ) -p, C H ), [Au( BuC DEGREESN DEGREESC Bu)(C≡CR′′)] (H BuC DEGREESN DEGREESCBuH = 2,6- 6 4 6 5 2 6 13 bis(4-tert-butylphenyl)pyridine; R′′ = C H, C H-NH -p, Si(CH ), H), 6 5 6 4 2 3 3 [Au(FC DEGREESN DEGREESCF)(C≡CR′′)] (HFC DEGREESN DEGREESCFH = 2,6-bis(4-fluorophenyl)pyridine; R′′ = C H, 6 5 C H-NH -p) and [Au(C DEGREESNTol DEGREESC)(C≡CC H-C H -p)] (HC DEGREESNTol DEGREESCH = 2,6- 6 4 2 6 4 6 13 diphenyl-4-p-tolylpyridine) have been synthesized. Most of the complexes have been structurally determined by X-ray crystallography which revealed the presence of intermolecular π-π stacking interaction with interplanar separations between [Au(RC DEGREESN(R′) DEGREESCR)] units of ca. 3.343-3.570 A. The lowest-lying excited states of 3 these complexes in dichloromethane were assigned as the metal-perturbed IL [π → π*(RC DEGREESN(R′) DEGREESCR)] origin, with substantial charge transfer character from the aryl ring to the pyridyl unit, whereas a switch in the lowest-lying excited states origin to LLCT [π(C≡CC H NR′′′ ) → π*(RC DEGREESN(R′) DEGREESCR)] was observed in complexes 6 4 2 containing aminophenyl alkynyl ligands. The low-energy emissions in the solid state were attributed to the π-π excimeric intraligand phosphorescence, arising from the intermolecular π-π stacking interactions of the RC DEGREESN(R′) DEGREESCR ligands in the solid state as revealed from the crystal packing diagrams. A series of luminescent mononuclear cyclometalated gold(III) complexes with various oligoynyl ligands, [Au(RC DEGREESN DEGREESCR)(C≡CR′)] (R = H, R′ = C≡CH, C H-C≡CH, C≡CC H, C≡CC H-CH -p, C≡CC H-CF -p, C≡CC H-NH -p, 6 4 6 5 6 4 3 6 4 3 6 4 2 C≡C-C≡CC H; R = Bu, R′ = C≡CH, C H-C≡CH) have also been synthesized. 6 5 6 4 The di- and trinuclear cyclometalated gold(III) alkynyl complexes, [1,4- t t t t {Au( BuC DEGREESN DEGREESC Bu)C≡C} C H ] and [1,3,5-{Au( BuC DEGREESN DEGREESC Bu)C≡C} C H ], have also 2 6 4 3 6 3 been prepared. The X-ray crystal structures of [Au(RC DEGREESN DEGREESCR)(C≡CR′)] (R = H, R′ = C≡CH, C H-C≡CH, C≡CC H-CH -p, C≡CC H-CF -p; R = Bu, R′ = 6 4 6 4 3 6 4 3 t t C H-C≡CH) and [1,3,5-{Au( BuC DEGREESN DEGREESC Bu)C≡C} C H ] have been determined. The 6 4 3 6 3 t t molecular structure of [1,3,5-{Au( BuC DEGREESN DEGREESC Bu)C≡C} C H ] showed the twisting of 3 6 3 t t the three coordination planes, [Au( BuC DEGREESN DEGREESCBu)], relative to the central phenyl ring with dihedral angles of 6.1, 48.4 and 60.7. Similarly, the emissions of most of the complexes in fluid solution were attributed to the metal-perturbed IL [π → π*(RC DEGREESN DEGREESCR)] phosphorescence with substantial charge transfer character from the aryl group to the pyridyl unit, while the emission origin was assigned as derived 3 f