Synthesis, photophysical and photochemical properties of substituted zinc phthalocyanines

Abstract

The synthesis, photophysical and photochemical properties of the 4-({3,4,5- tris-[2-(2- ethoxyethoxy)ethyloxy] benzyl} oxy) and 4-({3,4,5- tris-[ 2-( 2- ethoxyethoxy) ethyloxy] benzyl} thio) zinc( II) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, H-1 and C-13 NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen, fluorescence and triplet excited state quantum yields, and triplet state and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). The fluorescence of the complexes was quenched by benzoquinone (BQ). The effects of the substitution on the photophysical and photochemical parameters of the zinc( II) phthalocyanines ( 6, 7 and 8) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The substituted Zn( II) phthalocyanines showed high triplet and singlet oxygen quantum yields. High singlet oxygen quantum yields are very important for Type II mechanism. Thus, these complexes show potential as Type II photosensitizers.