Synthesis, photophysical and photochemical properties of poly(oxyethylene)-substituted phthalocyaninato oxotitanium(IV) complexes

Abstract

The synthesis, photophysical and photochemical properties of tetra- and chlorotetrapoly(oxyethylene) -substituted oxotitanium(IV) plithalocyanines are reported for the first time. The new compounds were characterized by elemental analysis, IR, H-1 and C-13 NMR spectroscopy, electronic spectroscopy and mass spectra. These complexes showed monomeric behaviour in solution. General trends are described for photo de gre dation, singlet oxygen, triplet state and fluorescence quantum yields, and triplet and fluorescence lifetimes of these compounds in dimethyl sulfoxide (DIVISO). Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The complexes showed high triplet quantum yields and triplet lifetimes in DMSO. The singlet oxygen quantum yields (0,,J, which give an indication of the potential of the complexes as photo sensitizers in applications where singlet oxygen is required (Type 11 mechanism), were 0.72 and 0.78 for 3a and 5a, respectively. Thus, these complexes show potential as Type 11 photos ensitizers. These complexes were also quenched by benzoquinone for fluorescence quenching studies. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).