At the end of this thesis, the 1H and 13C{ 1H} NMR spectra for all the new compounds and the crystallographic data are given as an Appendix. / Chapter 1 presents an overview of phthalocyanines and subphthalocyanines, including their general synthesis, properties, photosensitizing applications, and supramolecular chemistry. / Chapter 2 describes the synthesis and spectroscopic characterization of a series of subphthalocyanines axially substituted with an oligoethylene glycol chain [SPcB(OCH2CH2)nOH] (n = 3, 4) or a p-phenoxy oligoethylene glycol methyl ether chain [SPcBOC 6H4(OCH2CH2)nOCH3] (n = 2, 3). Their in vitro photodynamic activities toward HT29 human colorectal adenocarcinoma and HepG2 human hepatocarcinoma cells have also been investigated. In general, these compounds are essentially non-aggregated, resulting in a strong fluorescence emission and high efficiency to generate singlet oxygen. Being formulated with Cremophor EL, these subphthalocyanines function as efficient photosensitizers and exhibit a high photocytotoxicity. The phenoxy analogues show a relatively high photostability and are particularly potent toward these cell lines. / Chapter 3 reports the synthesis, spectroscopic characterization, and in vitro photodynamic activities of a new series of water-soluble subphthalocyanines. The photodynamic activities of these compounds against HepG2 and HT29 cells have also been evaluated. They exhibit high singlet oxygen quantum yields, but different degree of photostability, which greatly affects their photocytotoxicity. The relatively high photostability of the carboxy subphthalocyanine and its salts renders them highly photocytotoxic. / Chapter 4 describes the axial coordination of two subphthalocyanines having an axial pyridyl group with several tetrapyrrole derivatives, including zinc(II) and ruthenium(II) porphyrins and phthalocyanines. By using various spectroscopic methods and X-ray diffraction analyses, the formation of 1:1 hetero-dyads has been confirmed. The binding constants between the pyridyl subphthalocyanines and these metallotetrapyrrole derivatives have also been determined by a fluorescence titration method. / Chapter 5 presents the synthesis and spectroscopic characterization of a covalently linked subphthalocyanine-cyclodextrin conjugate. The host-guest interactions between this compound and a tetra-sulfonated porphyrin in aqueous medium have been investigated by various spectroscopic methods. This supramolecular system exhibits an efficient photo-induced energy transfer process from the excited subphthalocyanine core to the porphyrin moiety. This host-guest approach provides a new strategy to construct mixed subphthalocyanine and porphyrin systems, which have not been explored so far. / Chapter 6 reports the use of a series of zinc(II) and silicon(IV) phthalocyanines as photocatalysts for the photooxidation of olefins and 1-naphthol. These compounds are efficient photosensitizers producing singlet oxygen to form the oxidized products in high yields. The only exceptions are two dendritic silicon(IV) phthalocyanines which have a relatively low efficiency to generate singlet oxygen. Three photosensitizers have also been examined for their recyclability in the photooxidation of alpha-terpinene and furan-2-carboxylic acid. All of them can be recycled at least four times without a significant loss of catalytic activity. / This thesis reports our investigation of two versatile classes of functional dyes, namely phthalocyanines and subphthalocyanines, focusing on their photosensitizing applications and supramolecular chemistry. / Xu, Hu. / Adviser: Dennis K. P. Ng. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3506. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.