by Fuquan Song. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 204-205). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

A series of alkynylplatinum(II) polypyridine complexes with 4,4′,4′′-tricarboxy-2,2′:6′,2′′-terpyridine and 4,4′-dicarboxy-2,2′-bipyridine as TiO2 anchoring functionalities, has been successfully synthesized. Their photophysical, electrochemical and luminescence properties have been extensively studied. The excited state properties were probed using nanosecond transient absorption spectroscopy. [Pt(tctpy)(C≡C-Th-BTD-Th)][NnBu4]2 displayed a long-lived transient signal which was tentatively assigned to result from the formation of a charge-separated state, which could be alternatively described as a [Pt(tctpy)???(C≡C-Th-BTD-Th)+?] state, with the charge recombination rate constant determined to be 2.9 × 105 s?1. The excited state redox potentials for the oxidation process were determined and the data confirmed the ability of the complexes to inject an electron into the conduction band of TiO2. The majority of the complexes were found to sensitize the nanocrystalline TiO2 and exhibit photovoltaic properties, which have been characterized by current-voltage measurements under illumination of air mass (AM) 1.5G sunlight (100 mW cm–2). A new class of molecular dyads comprising metalloporphyrin-linked alkynylplatinum(II) polypyridine complexes was synthesized and characterized. Their photophysical, electrochemical and luminescence properties have been studied in detail. The excited state properties were probed using nanosecond transient absorption spectroscopy which indicated the formation of a charge-separated state involving the porphyrin radical anion, [Por??－(C≡C)Pt+?]. The excited state redox potentials for the oxidation process were also determined with the data supporting the capability of the complexes to inject an electron into the conduction band of TiO2. The majority of the complexes were found to sensitize the nanocrystalline TiO2 and exhibit photovoltaic properties, as characterized by current-voltage measurements under illumination of air mass (AM) 1.5G sunlight (100 mW cm–2). A series of organic materials consisting of a triphenylamine-based donor with oligothiophene or oligothienylenevinylene based-conjugated linker and dicyanovinyl, tricyanovinyl or cyanacrylic acid groups as acceptor, was synthesized and characterized. Their photophysical, electrochemical, thermal and luminescence properties were studied. Transient absorption spectra of TPA-OTV-DCN in dichloromethane solution on the pico- to nanosecond timescale were recorded after femtosecond laser excitation at 400 nm. A transient signal at ca. 700 nm was tentatively assigned to result from the formation of a charge-separated [(TPA-OTV)+??DCN??] state with the charge recombination rate constant determined to be 5.3 × 109 s?1. The energy levels of the LUMOs of TPA-OTV1-DCN, TPA-OTV2-DCN, TPA-OTV3-DCN TPA-TAZ1-DCN, TPA-TAZ2-DCN and TPA-o-4Th-DCN were calculated to be of ca. ?3.9 eV, establishing the formation of a downhill driving force for the energetically favorable electron transfer process involving the injection of an electron into the LUMO of the C60 acceptor. The majority of the compounds were found to exhibit photovoltaic properties. The photovoltaic responses were characterized by current-voltage measurements under illumination of air mass (AM) 1.5G sunlight (100 mW cm–2). / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

In this dissertation novel non-leaving groups were employed to synthesize platinum complexes which can contribute to the understanding or improvement of anticancer action. These complexes basically consist of (NS)-chelate and amineplatinum complexes. Bidentate (NS)-donor ligands were used as non-leaving ligands in the syntheses of platinum(II) complexes with iodide, chloride, bromide and oxalate anions as leaving groups. These complexes were synthesized and studied since many questions regarding the interaction of sulfur donors and platinum still exists. These relate to thermodynamic and kinetic factors and their influence on anticancer action. In this dissertation the properties of novel platinum(II) complexes of a bidentate ligand having an aromatic nitrogen-donor atom in combination with a thioethereal sulfur atom capable of forming a five membered ring with platinum(II) were studied. The general structure of the (NS) -ligands used were N-alkyl-2-methylthioalkyl imidazole. Alkyl groups used were methyl, ethyl and propyl. Although amine complexes of platinum have been extensively studied there are some new aspects of these that are worthwhile investigating. In this dissertation amines having planar attachments which will be at an angle with the coordination plane viz. benzylamine and amines having cyclic aliphatic groups namely cyclopropyl and cyclohexyl were investigated. Some of the (NS) - and amineplatinum(II) complexes were oxidised to their mononitroplatinum(IV) analogues . The motivation for the synthesis of these complexes was the greater kinetic stability of platinum(IV) and recent research has shown that a specific type of platinum(IV) compound shows suitable properties as an anticancer agent. These complexes were characterised by a variety of spectral means (IR, NMR, mass spectroscopy) as well as elemental analysis, solubility determinations, thermal analysis (TGA), ionization studies and finally their anticancer behaviour towards three different cell lines(Hela, MCF 7, Ht29) and in this process they were compared to the behaviour of cisplatin as a reference. A few have shown promising anticancer behaviour.

Novel non-leaving groups were employed in this dissertation to synthesize platinum complexes which can assist in the understanding or improvement of anticancer action. Emphasis was placed on (NS)-chelate and (NN)-chelate platinum complexes. Bidentate (NS)-donor ligands were used as non-leaving ligands in the synthesis of platinum(II) complexes with iodo, chloro, bromo and oxalato groups as leaving groups. These complexes were synthesized and studied since many questions regarding the interaction of sulfur-donors and platinum still exist. These relate to thermodynamic and kinetic factors and their influence on anticancer action. In this dissertation the properties of novel platinum(II) complexes of a bidentate ligand having an aromatic nitrogen-donor atom in combination with a thioethereal sulfur atom capable of forming a five-membered ring with platinum(II) were studied. The general structure of the (NS)-ligands used was 2-((alkylthio)methyl)pyridine. Alkyl groups used were methyl, ethyl, propyl, benzyl and phenyl. Amine complexes of platinum have been studied extensively in the past. However, attention was given to novel aspects of substituted pyridine and imidazole ligands and their corresponding complexes. Amongst these are 2-(2-methylaminoethyl)pyridine, 1-methyl-2-methylaminoethylimidazole and 1-methyl-2-methylaminobenzylimidazole. The leaving groups included chloro, bromo and oxalato. Mononitroplatinum(IV) complexes were prepared using novel synthetic methods. Selected platinum(II) amine complexes were used as starting materials for this synthesis. Some of these compounds exhibit promising anticancer behaviour. (Trans-(R,R)-1,2-diaminocyclohexane)(oxalato)(mononitrochloro)platinum(IV) is a particularly good anticancer agent and has been patented internationally. All these complexes were characterized using mass spectrometry, chromatography, thermogravimetric analysis, kinetic aspects such as ligand exchange rates and finally their anticancer action against three different cancer cell lines was evaluated via cytotoxicity assays. Some of the compounds exhibited particularly good anticancer potential.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Master / Master of Philosophy