The phthalocyanines are a family of intensely coloured compounds (usually blue or green) which are structurally similar to the porphyrins. A brief summary of different phthalocyanines reported in the literature so far, their preparations and applications are detailed in the introductory chapter. A number of substituted phthalocyanines are already known as effective photosensitisers for photodynamic therapy (PDT). Therefore the design and synthesis of a series of new unsymmetrically substituted phthalocyanine derivatives has been described. Also the preparation of a series of phthalocyanines bearing one or more 4- tert-butylphenyl substituents was investigated. Reports in the literature suggested such derivatives should be able to bind to cyclodextrins to afford water soluble formulations. The synthesis of highly soluble axially substituted phthalocyanine derivatives containing indium within the macrocycle cavity is described. These materials have been found to have useful optical and electrical properties. One compound of this series is chiral and its solid state structure has been determined by X-ray diffraction analysis. The synthesis of metallated and non-metallated porphyrazines has been explored. The metal-free derivative generates conventional "face-to-face" assemblies in solution, whereas the zinc analogue forms alternative "edge-to-face" complexes via axial ligation. Finally, the research described in the fourth chapter involves the synthesis of new alkylsulfanyl and arylsulfanyl phthalocyanine derivatives. The complexation of such materials with silver(I) ion has been investigated and monitored by UV/vis spectroscopy.