Synthesis, photophysical and photochemical properties of tetra- and octa-substituted gallium and indium phthalocyanines

Abstract

The synthesis, photophysical and photochemical properties of the tetra- and octa-[4-(benzyloxyphenoxy)] substituted gallium(Ill) and indium(III) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, H-1 NMR spectroscopy and electronic spectroscopy. General trends are described for quantum yields of photodegredation, fluorescence quantum yields and lifetimes, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulfoxide (DMSO). Substituted indium phthalocyanine complexes (7b-9b) showed much higher quantum yields of triplet state and shorter triplet lifetimes. compared to the substituted GaPc derivatives due to enhanced intersystem crossing (ISC) in the former. The gallium and indium phthalocyanine complexes showed phototransformation during laser irradiation due to ring reduction. The singlet oxygen quantum yields (Phi(Delta)), which give an indication of the potential of the complexes as photo sensitizers in applications where singlet oxygen is required (Type 11 mechanism) ranged from 0.51 to 0.94. Thus, these complexes show potential as photodynamic therapy of cancer. (c) 2007 Elsevier Ltd. All rights reserved.