The syntheses of tetra- and octa-substituted phthalocyanine complexes of titanium (IV) oxide vanadium (IV) oxide and tantalum (V) hydroxide and their electrochemical characterisation are presented in this work. The structures and purity of these complexes were confirmed by NMR, infrared and mass spectroscopies and elemental analysis. They show good solubility in most common solvents especially non-viscous solvents such as dichloromethane and chloroform. The cyclic voltammograms (CV) showed reversible to quasi reversible behavior for all the reduction couples and the oxidation peaks were irreversible. Spectroelectrochemistry of the complexes confirmed metal and ring redox processes for TaPc and TiPc derivatives and ring based processes only for VPc complexes. The synthesis of gold nanoparticles and their conjugation with the new phthalocyanines was carried out. Similarly, single walled carbon nanotubes were conjugated to selected tantalum complexes and the characterization of all the nanomaterials and their conjugates using different techniques that include TEM, XRD and AFM is also presented in this work. The photophysical and photochemical properties and photocatalytic oxidation of cyclohexene properties of the newly synthesised in the presence of gold nanoparticles were investigated. The compounds were stable, well within the stability range for phthalocyanines. The singlet oxygen quantum yield values increased drastically in the presence of gold nanoparticles. The photocatalytic products obtained from the reaction were cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,4-cyclohexanediol. The percentage conversion values, yields and selectivity values improved significantly in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The electrocatalytic oxidation of bisphenol A and p-nitrophenol was carried out using nickel tetraamino phthalocyanine and all the newly synthesised metallophthalocyanine in the presence of gold nanoparticles and single walled carbon nanotubes. The charge transfer behaviour of AuNPs was enhanced in the presence of TaPc, TiPc and VPc complexes. The presence of single walled carbon nanotubes further improved electron transfer and minimised electrode passivation.

Synthesis of new thio derivatised Pcs with manganese, titanium and vanadium as a central metal is reported. The complexes synthesised were characterised using spectroscopic and electrochemical means. The complexes displayed interesting spectroscopic properties with absorption of the Q band being observed in the near infrared region. These complexes have unusual colours for MPc complexes, with purple or red colour being observed in solution. Interesting electrochemical properties were observed, with rare observation of the MnIV/MnIII redox couple. There was observation of oxidation peaks for the pentylthio derivatised Pc with titanium as the central metal; this is unusual since for reported thio derivatives based on TiPc, no oxidation was observed. The vanadium based Pc showed an interesting spectrum for the first ring based reduction. The absorption spectrum obtained for the 1st reduction of the vanadium complex using spectroelectrochemistry would normally indicate a metal based process but comparing with literature it was concluded that it is a ring based reduction process. Generally all the MPc complexes formed a well ordered stable monolayer on the gold electrode. Electrocatalytic studies using L-cysteine revealed that the SAM based on manganese (III) octapentylthio phthalocyanine (AcOMnOPTPc) was the most effective since it catalyses L-cysteine at much lower oxidation potentials and it is also much more stable.

1H and 13C{1H} NMR spectra of all the new compounds and crystallographic data are given in the Appendix. / Chapter 1 presents an overview of phthalocyanines including their general synthesis, properties, and applications. Special attention has been placed on the unsymmetrical analogues, and those which are efficient photosensitizers in photodynamic therapy. A brief account on BODIPYs as another versatile class of functional dyes is also given. / Chapter 2 describes the synthesis, spectroscopic characterization, photophysical properties, and in vitro photodynamic activities of three novel amphiphilic zinc(II) phthalocyanines substituted with one or two 3,4,5-tris(3,6,9-trioxadecoxy)benzoxy group(s). These compounds exhibit significantly higher photodynamic activities toward HepG2 and HT29 cell lines. The alpha-substituted analogue is particularly potent with IC50 values as low as 0.02 microM. The higher photodynamic activity of this compound can be attributed to its lower aggregation tendency in the culture media as shown by absorption spectroscopy and higher cellular uptake as suggested by the stronger intracellular fluorescence, resulting in a higher efficiency to generate reactive oxygen species inside the cells. / Chapter 4 focuses on a related series of 1,4-disubstituted zinc(II) phthalocyanines. These compounds possess two oligoethylene glycol methyl ether chains with various length at the 1,4-di-alpha-positions. The effects of the chain length on their aggregation, photophysical properties, cellular uptake, and in vitro photodynamic activities have been explored. / Chapter 5 presents the synthesis, characterization, and photophysical properties of another series of zinc(II) phthalocyanines conjugated with one, two or four isopropylidene protected glucofuranose unit(s) through a tetraethylene glycol linker. With these hydrophilic substituents, these macrocycles are highly soluble in common organic solvents and biological media. Their in vitro photodynamic activities toward HT29 and HepG2 cells have also been evaluated. Compared with the tetra-glucosylated phthalocyanines, which are almost nonphotocytotoxic, the mono- and di-glucosylated analogues exhibit a higher photodynamic activity. The di-alpha-substituted analogue is particularly potent with IC50 values as low as 0.03 microM. / Chapter 6 reports the synthesis, characterization, and photophysical properties of two novel conjugates of subphthalocyanine substituted axially with a BODIPY or distyryl-BODIPY moiety. Both systems absorb over a broad range in the visible region. They also exhibit a highly efficient photo-induced energy transfer process either from the excited BODIPY to the subphthalocyanine core or from the excited subphthalocyanine to the distyryl-BODIPY unit. The energy transfer quantum yields are close to unity for both of these conjugates. / Chapter 7 describes the preparation and photophysical properties of another two BODIPY and monostyryl-BODIPY conjugates which are linked to a silicon(IV) phthalocyanine core. These conjugates serve as excellent artificial photosynthetic models for the study of energy and electron transfer processes. Depending on the axial substituents, these conjugates exhibit predominantly a photo-induced energy or electron transfer process in toluene. / The related studies of a series of novel di-alpha-substituted zinc(II) phthalocyanines having two biocompatible triethylene glycol methyl ether chains or glycerol moieties are described in Chapter 3. Compared with the unsubstituted analogue, these compounds have a red-shifted Q band, and exhibit a relatively weaker fluorescence emission and higher efficiency to generate singlet oxygen. As a result, these compounds are promising candidates for photodynamic therapy. In vitro studies on HepG2 and HT29 cells have shown that they are highly photocytotoxic with IC50 values as low as 0.06 microM. / This thesis describes my synthetic studies on several series of functional zinc(II) phthalocyanines and boron dipyrromethenes (BODIPYs). Their applications as efficient photosensitizers in photodynamic therapy and light harvesting systems have also been explored. / Liu, Jianyong. / Adviser: Dennis Keepui Ng. / Source: Dissertation Abstracts International, Volume: 71-01, Section: B, page: 0326. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references. / 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. / Abstracts in English and Chinese.

At the end of this thesis, the 1H and 13C {1H} NMR spectra of all the new compounds are listed in the Appendix. / Chapter 1 presents an overview of BODIPYs, including their general synthesis, properties, reactivities, and applications. The use of these compounds as photosensitizers for photodynamic therapy and fluorescent sensors for metal ions is highlighted. / Chapter 2 reports the synthesis, spectroscopic characterization, photophysical propreties, and in vitro photodynamic activities of a series of symmetrical distyryl BODIPYs substituted with one to five hydrophilic oligoethylene glycol monomethyl ether chain(s). In general, these compounds are essentially non-aggregated in DMF, resulting in a strong fluorescence emission and relatively high efficiency in generating singlet oxygen. Being formulated with 0.05% Tween 80, these compounds act as efficient photosensitizers. The compound which contains five triethylene glycol monomethyl ether chains exhibits the highest photocytotoxicity with an IC50 value as low as 7 nM toward HT29 human colorectal carcinoma cells. The high photodynamic activity of this compound can be attributed to its high efficiency in generating singlet oxygen, low aggregation tendency, and high cellular uptake. In addition, this compound also has a strong and selective affinity to the endoplasmic reticulum of the cells, causing cell death mainly through apoptosis. / Chapter 3 reports a related study on a series of unsymmetrical distyryl BODIPYs. These compounds possess three triethylene glycol monomethyl ether chains and another substituent at the other styryl group. The effects of this substituent on the photophysical properties, aggregation behavior, cellular uptake, and subcellular localization have been explored. Furthermore, their in vitro photodynamic activities have also been evaluated and compared with those of symmetrical analogues reported in Chapter 2. / Chapter 4 describes a novel ratiometric near-infrared fluorescent dye based on distyryl BODIPY with a 4-dimethylaminophenylethynyl group at the 2- and 6-positions. This compound exhibits a remarkable blue-shift in its absorption and fluorescence emission positions upon protonation with trifluoroacetic acid in organic solvents or HC1 in water in the presence of 0.05% Tween 80. These changes can be made reversible upon addition of a base. / Chapter 5 describes two monostyryl BODIPYs which contain two or four water-soluble amide chains as the metal chelators. The photophysical properties of these compounds and their spectral response to various metal ions have been investigated. The results show that the compound with two amide chains can detect Zn2+ ion in MeCN. They bind in a 1:1 stoichiometry with a binding constant of 2.2 x 104 M-1 . The fluorescence emission increases remarkably in intensity and shifts substantially to the blue from 620 to 572 nm due to the inhibition of the intramolecular charge transfer. The compound which contains four amide chains can detect Cd2+ ion with a high selectivity in phosphate buffered saline. / Chapter 6 reports the synthesis and spectral properties of a silicon(IV) phthalocyanine with two axial bis(2-picolyl)amine moieties which act as the binding sites for metal ions. The effects of various metal ions on its absorption and fluorescence spectra have been examined. The results indicate that this compound shows a relatively high sensitivity to Zn 2+ ion. Moreover, the proposed binding mode and the sensing mechanism are also discussed. / This thesis describes the synthesis and characterization of several series of functional boron dipyrromethenes (BODIPYs) and a silicon(IV) phthalocyanine. Their applications as efficient photosensitizers in photodynamic therapy and selective fluorescent sensors for metal ions are also reported herein. / He, Hui. / Adviser: Dennis Kee Pui Ng. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references. / 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, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.