The synthesis and photophysical properties of novel phthalocyanines for potential application in photodynamic therapy.
Phthalocyanines are a group of molecules, which have been studied extensively due
partly to their use and potential in a wide variety of applications, but also on account
of the seemingly endless list of differently substituted moieties, which in principle
may be prepared. The history of the compounds in general are discussed briefly in
Chapter 1 of this thesis, while Chapter 2 focuses on Photodynamic Therapy, an area in
which they have more recently been found to exhibit excellent potential.
The synthesiso of novel phthalocyanines for potential application in PDT is reported in
Chapter 3. The current research investigated the synthesis of binuclear Pcs from the
linking of two preformed phthalocyanine rings by means of an oxalyl bridge
functionality and also from the mixed cyclisation of phthalonitriles with bisphthalonitriles,
which proved to be extremely problematic.
The synthesis of water-soluble phthalocyanine derivatives was investigated as a
sideline, which resulted in the synthesis of a novel phthalocyanine monomer
substituted with eight triethylene glycol chains. Efforts to synthesise a phthalocyanine
linked to a glucose unit were unsuccessful.
Chapter 4 describes research into the photophysical properties of a number of
mononuclear and binuclear phthalocyanines synthesised both in the current work and
also compounds synthesised by co-workers. The electronic absorption and
fluorescence spectra of the compounds are investigated, and the absorption spectrum
of a purely cofacial dimeric structure is obtained by calculation from the spectrum of
one of the binuclear derivatives. Laser Flash Photolysis was performed on a number
of the samples, determining triplet lifetimes, triplet quantum yields and singlet oxygen
The effect of aggregation on the photoproperties of phthalocyaninesis investigated in
Chapter 5. The current work involved low temperature absorption and fluorescence
spectroscopy on a number of mononuclear and binuclear phthalocyanine derivatives.
The nature of the aggregated structures, which were observed to form at 77K, are then
rationalised with reference to previous research into phthalocyanine aggregates and