published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

M.Sc. / [AuCl(PPh3)] was reacted with mixed thiols in the presence of silver(I) oxide, resulting in complexes of the type [Au(SC6H4X)(PPh3)] X= Cl, NH2,CH2, forming silver chloride as a by-product. In addition to the above series [Au(SCH2(C6H4)3(2-C6H5(C6H4N)] was prepared via a different route, where [AuCl3(2-C6H5(C6H4N)] was reacted with benzyl mercaptan under reflux in the presence of silver(I) oxide for 3 h, forming silver chloride as a by-product. Palladium complex [PdCl2(2-C6H5(C6H4N)] was prepared by reacting [PdCl2(MeCN)] with 2-phenylpyridine at room temperature for 2 h. All complexes were characterized by 1H, 13C, 31P{H} NMR, IR, mass spectrometry and elemental analysis. Characterization of the starting materials [AuCl3(2-C6H5(C6H4N)] and [PdCl2(2- C6H5(6H4N)] by single crystal X-ray diffraction confirmed their chemical formula. All complexes were reacted with sulfur dioxide (SO2) and the reactions were monitored by electrochemistry and UV-vis spectroscopy. The electrochemical study of the complexes, using cyclic voltammetry (CV) and Osteryoung square wave voltammetry (OSWV), showed one anodic peak, which is due to gold(I/III) and an unresolved peak due to thiolate ligand. Upon bubbling of SO2 to the complexes, there was an immediate change of colour from clear to yellow, the CV results showing an increase in current of the gold(I/III) peak. UV-vis spectroscopy studies showed a shift of peak form 250-286 nm, upon bubbling of SO2 to complexes.

Doctor of Philosophy(PhD) / The present study deals with the synthesis and characterization of six tri-palladium complexes code named MH3, MH4, MH5, MH6, MH7 and MH8 that contained two planaramine ligands bound to the central or each of the terminal metal ions. The activity of the compounds against human cancer cell lines: A2780, A2780cisR and A2780ZD0473R, cell uptake, levels of DNA-binding and nature of interaction with salmon sperm and pBR322 plasmid DNA have also been determined. Whereas cisplatin binds with DNA forming mainly intrastrand GG adduct that causes local bending of a DNA strand, the tri-palladium complexes are expected to bind with DNA forming a number of long-range interstrand GG adducts that would cause a global change in DNA conformation. Among the designed complexes, MH6 that has two 2-hydroxypyridine ligands bound to each of the two terminal palladium ions is found to be most active. The compound also has the highest cell uptake and Pd-DNA binding levels. In contrast, MH8 which has two 4-hydroxypyridine ligands bound to each of the two terminal palladium ions is found to be least active. The results indicate that, as applied to the terminal metal centres, 2-hydroxypyridine would be more activating than 4-hydroxypyridine perhaps because of greater protection provided to the terminal centres from coming in contact with the solvent molecules. In contrast, when bound to the central metal centre, 4-hydroxypyridine appears to play a slightly greater activating role than 2-hydroxypyridine or 3-hydroxypyridine, suggesting that non-covalent interactions such as hydrogen bonding associated with the ligand rather than its steric effect may be a more important determinant of antitumour property. The results illustrate structure-activity relationships and suggest that the tri-palladium complex containing two 2-hydroxypyridine ligands bound to each of the three metal centres or the compound that contains two 2-hydroxypyridine ligands bound to each of the two terminal metal centres and two 4-hydroxypyridine ligands bound to the central metal centre, may be much more active than any of the designed complexes.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Doctor of Philosophy(PhD) / The present study deals with the synthesis and characterization of six tri-palladium complexes code named MH3, MH4, MH5, MH6, MH7 and MH8 that contained two planaramine ligands bound to the central or each of the terminal metal ions. The activity of the compounds against human cancer cell lines: A2780, A2780cisR and A2780ZD0473R, cell uptake, levels of DNA-binding and nature of interaction with salmon sperm and pBR322 plasmid DNA have also been determined. Whereas cisplatin binds with DNA forming mainly intrastrand GG adduct that causes local bending of a DNA strand, the tri-palladium complexes are expected to bind with DNA forming a number of long-range interstrand GG adducts that would cause a global change in DNA conformation. Among the designed complexes, MH6 that has two 2-hydroxypyridine ligands bound to each of the two terminal palladium ions is found to be most active. The compound also has the highest cell uptake and Pd-DNA binding levels. In contrast, MH8 which has two 4-hydroxypyridine ligands bound to each of the two terminal palladium ions is found to be least active. The results indicate that, as applied to the terminal metal centres, 2-hydroxypyridine would be more activating than 4-hydroxypyridine perhaps because of greater protection provided to the terminal centres from coming in contact with the solvent molecules. In contrast, when bound to the central metal centre, 4-hydroxypyridine appears to play a slightly greater activating role than 2-hydroxypyridine or 3-hydroxypyridine, suggesting that non-covalent interactions such as hydrogen bonding associated with the ligand rather than its steric effect may be a more important determinant of antitumour property. The results illustrate structure-activity relationships and suggest that the tri-palladium complex containing two 2-hydroxypyridine ligands bound to each of the three metal centres or the compound that contains two 2-hydroxypyridine ligands bound to each of the two terminal metal centres and two 4-hydroxypyridine ligands bound to the central metal centre, may be much more active than any of the designed complexes.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 118-126).

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

D.Phil. / Porphyrazines like porphyrins and phthalocyanines have unique physical, chemical and spectral properties. This allows them to have many impressive applications. They are less studied than phthalocyanines because of the absence of convenient methods for their synthesis. However, recent studies, including this one, have made these compounds more accessible. The palladium-imidazolium salt systems have proved to be one of the most successful catalysts for the Heck and Suzuki coupling reactions. Substituents on nitrogen atoms of imidazolium significantly influence the catalytic activities of the corresponding palladiumimidazolium salt systems in the Heck and Suzuki coupling. The synthesis of the imidazolium salts is discussed in this study. The synthesis of the imidazoles started from diamines. A new route for the synthesis of 4,5-diaminophthalonitrile is discussed here and so far it is the most convenient and less tedious route with higher yields. The catalytic activities on different substrates have also been extensively investigated and gave impressive results, on the Heck and Suzuki reaction. The catalysis study was first performed using the dicyanoimidazolium salts and then with the imidazolium salts of the porphyrazines. The results indicate that both these systems are active ligands for Suzuki and Heck reactions. Two complexes, [1’,1’’-dibutyl-3’,3’’-(4,5-(1,2-dicyanobenzene))diimidazolium dibromide] and [2,3-benzo(2’,3’-(3’’,3’’’-dibutyldiimidazolium-2’,2’’-diylidene)palladium(II)- dibromide)-7,8,12,13,17,18-hexapropyl,porphyrazine] were synthesised successfully in good yields and used for Suzuki and Heck catalysis reactions. Catalyst recovery in homogeneous catalysis is always a major problem; this led this study to make use of porphyrazines in biphasic catalysis because of their high extinction coefficient which comes from their very intense colour. The reactions were performed in a combination of water with toluene and also water with ionic liquid. Both this systems gave results which proved that it is possible to separate the catalyst and the products once the reaction is complete. Two aminoporphyrazines and phthalonitriles were also synthesised in multistep synthesis. The synthesis involved a lot of protection and deprotection steps. These compounds are starting materials to aminophosphine ligands which have a wide variety of catalysis applications.

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

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