At the end of this thesis, 1H and 13C{ 1H} NMR spectra for all the new compounds and the crystallographic details for the X-ray structure are given as Appendices. / Chapter 1 presents an overview of photodynamic therapy, including its historical development, photophysial and biological mechanisms, and current clinical situation. A brief review of second-generation photosensitizers and the different approaches for targeted photodynamic therapy are also given. / Chapter 2 reports the synthesis and characterization of a silicon(IV) phthalocyanine which is substituted axially with two diamino moieties, together with its di- and tetramethylated derivatives. The non-methylated analogue shows a high photocytotoxicity toward HT29 human colorectal adenocarcinoma and HepG2 human hepatocarcinoma cells with IC50 values down to 0.01 muM. Interestingly, this compound also exhibits a pH-dependent behavior. The fluorescence quantum yield increases by four folds and the singlet oxygen quantum yield increases by three folds in water when the pH decreases from 7.0 to 5.0. The preliminary results suggest that this compound is a promising photosensitizer of which the photodynamic activity can be modulated by changing the pH of the environment. Furthermore, this compound can be used as a near-infrared fluorescence probe for optical imaging of intracellular acidic level. / Chapter 3 reports a novel series of aminophenyl-substituted silicon(IV) phthalocyanines. The aminophenyl moieties in these conjugates can also modulate the photophysical and photosensitizing properties of the phthalocyanine core through changing the pH of the environment. These phthalocyanines exhibit a low photocytotoxicity under physiological conditions (pH 7.4). It is likely that the amino groups, in the free amine form, can quench the singlet excited state of phthalocyanine by a photoinduced electron transfer (PET) mechanism, and reduce the chance of intersystem crossing and the efficiency in generating singlet oxygen. The strong aggregation tendency of these compounds in this pH environment is another major reason for the low photocytotoxicity. When the pH is lower to 6.4-6.9, the amino groups are protonated so that they are no longer electron donors, and the compounds become less aggregated. These changes lead to an increase in photocytotoxicity. The results of this study are reported in this Chapter. / Chapter 4 describes a new series of silicon(IV) phthalocyanines conjugated axially with various polyamine derivatives. Polyamines are naturally occurring compounds which are involved in a number of cell processes including cell proliferation and differentiation. Their biosynthetic activity and polyamine levels in some tumor cells are significantly higher than those in normal cells. Conjugation of polyamine analogues is therefore one of the promising approaches to improve the tumor-targeting property of photosensitizers. This Chapter describes the synthesis, spectroscopic characterization, and photophysical properties of these compounds. Their photodynamic activities toward HT29 and Chinese hamster ovary (CHO) cells have also been studied in detail. Their cellular uptake, subcellular localization, cell death mechanism, and in vivo photocytotoxicity have also been studied. / In Chapter 5, we report a series of silicon(IV) phthalocyanines containing one or two cholesterol unit(s) at the axial position(s), including their synthesis, spectroscopic characterization, photophysical properties, and in vitro photodynamic activities. These cholesterol-containing photosensitizers can form stable conjugates with low-density lipoprotein (LDL), which is the major lipoprotein carrier for cholesterol in human plasma. On the basis that cancer cells generally express significantly more LDL receptors than normal cells, these cholesterol-conjugated phthalocyanines are designed with a view to enhancing their selectivity toward tumor. Unfortunately, conjugation of cholesterol reduces the photodynamic activity of the silicon(IV) phthalocyanines as a result of their higher aggregation tendency. / This thesis reports the synthesis, spectroscopic characterization, and photophysical and biological properties of several series of novel silicon(IV) phthalocyanines which are specially designed as efficient and selective photosensitizers for photodynamic therapy. / Jiang, Xiongjie. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references and index. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

The lability of cobalt(III) in vitamin B12 is thought to come about as a function of its coordination environment. The thermodynamics and kinetics of ligand substitution reactions of vitamin B12a were compared to those of a synthetic, more electron rich, corrole-based biomimetic model. The feasibility of corrole synthesis was established with the synthesis of several corroles with different meso substituents. The biomimetic model was designed such that the central meso position bore a substituent with a terminal imidazole (referred to as the ‘tail’) which might act as an axial ligand for a coordinated cobalt ion while the remaining two meso positions bore water-solubilising glucose substituents. Unfortunately, the biomimetic model was water soluble below pH 4 only. This rendered the model unsuitable for the present study and these water solubilising groups were not incorporated into the final model. The model system used in this work is [10-(2-{[4-(1Himidazol-1-ylmethyl)benzoyl]amino}phenyl)-5,15-diphenylcorrolato]cobalt(III), referred to as DPTC-Co Intermediates of the ‘tail’ meso substituent were found to be polymorphic and five pairs of polymorphs were identified. Polymorphism arose from differences in weak termolecular forces and these differences were evaluated. The stability constants for the binding of various neutral N-, P- and S-donor ligands and anionic N-, S-, I- and C-donor ligands to both vitamin B12a and DPTC-Co were determined in a buffered 80:20 methanol:water solvent system. The more stable binding of neutral ligands to DPTC-Co and anionic ligands to vitamin B12a indicates that the interaction between the metal and an incoming ligand is indeed affected by the metal’s coordination environment. Cobalt(III) in DPTC-Co appeared to favour softer ligands while harder ligands were favoured by vitamin B12a. Kinetic studies showed that the coordination of cyanide to cobalt in vitamin B12a was faster than in DPTC-Co. The reaction between cyanide and vitamin B12a was found to be entropically driven while the reaction with DPTC-Co was enthalpically driven. This suggests that while the reaction between cyanide and vitamin B12a is faster, the reaction between cyanide and DPTC-Co is electronically more labile. The coordination environment of cobalt has been seen to significantly affect its chemistry. Coordination by the more electron rich corrole macrocycle led to a softer and more electronically labile metal then when coordinated by the corrin macrocycle of vitamin B12a.

One microfiche--`Data from crystal structures solved by the author`--in pocket / Bibliography: leaves 214-225 / 225 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1987

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

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

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

The epoxide deoxygenation reaction is formally the reverse of the epoxidation reaction. Compared to epoxidation, which has reached its full maturity, epoxide deoxygenation has not been as intensively developed. Among the few deoxygenation reagents, a handful are catalytic in a metal complex, show high stereospecificity and operate under mild conditions. A common feature of all present deoxygenation reagents is that they do not perform asymmetric deoxygenation of racemic epoxides. Rhenium (VII) trioxo complexes are emerging as pliable catalysts for epoxide deoxygenation. Designing a chiral rhenium (VII) trioxo complex was our goal. Guided by the mechanism of rhenium (VII) trioxo catalyzed epoxide deoxygenation and the mechanism of the stereogenic information transfer, we have designed and prepared a chiral rhenium(VII) trioxo complex. This complex is void of stereogenic centers and the source of asymmetry is the restricted rotation around a carbon-carbon bond. Detailed conformational analysis of the new chiral complex was done by extensive NMR measurements and molecular modeling. The rotation barrier for the diolate was experimentally and computationally estimated to be 9.72 kcal/mol and 8.06 kcal/mol, respectively. Unsuccessful attempts were made to prepare a camphor based scorpionate because of the extreme steric congestion. A menthone based scorpionate was successfully prepared. The related rhenium (TII) trioxo complex with this scorpionate revealed contradicting chemical and spectroscopic features. / Graduation date: 2005

Graduation date: 2003

Graduation date: 2002

A three part study involving aspects of radical properties of various aromatic species was accomplished. Experiments to ascertain the importance of geometric and electronic effects on the intramolecular transfer of a pi-complexed radical to a terminal double bond was performed. Several 4-aryl-1-butenes were reacted in competition with 1-undecene with a variety of radical precursors at 70��C. The reactions were studied in both complexing and noncomplexing solvents. Most of the relative rates varied little from unity and no dependence on solvent was observed. A series of 21 phenacylarenes was subjected to mass spectrometry. The fragmentation process leading to arylmethyl radicals and benzoyl cations was measured by calculating the ratios of parent ion to benzoyl cation signal strength. In the case of the eleven homoaromatic compounds little overall correlation of these values to traditionally accepted arylmethyl radical stabilities was found. The degree of fragmentation for isomers of the same compound were found to be explicable in term of arylmethyl radical stabilities. Degrees of fragmentation of some compounds could be rationalized in terms of the bond order of the bond being broken, as calculated by AM1 methods. The ten heteroaromatic compounds showed little correlation of fragmentation with bond order. The degree of fragmentation was found to be dependent on many different variables of the individual molecules. No correlation with any one factor could be found. The relative rates of benzylic hydrogen atom abstraction from a series of substituted toluenes and cumenes under conditions of bromination by diethyl bromomalonate were determined at 70��C. A range of reactivity of 21.7 and 10.5 was found for the toluenes and cumenes respectively. The relative rates were found to correlate best with Hammett sigma plus constants. Hammett values of -0.89 and -0.73 were calculated for the substituted toluenes and cumenes. Reactivities for several alkyl benzenes having different steric requirements at the reaction site were also studied. The relative rates for these compounds indicate a relatively large radical to be the atom abstracting agent. The results of the Hammett correlations combined with the studies involving the steric properties of the abstracting radical suggest that diethyl malonyl radical is the hydrogen atom abstracting species. / Graduation date: 1997