Abstract

The investigation of the effects of presence of central metal on the excited triplet state energy of octakis(pentylthio)-derivatisedphthalocyanines (-H2Pc, -H2Pc, -PdPc and -PdPc) is presented. Though all the molecules show high triplet quantum yield, the lack of correlation between triplet quantum yield and singlet oxygen quantum yield for the metal-free phthalocyanines (Pcs) is found to be a result of low triplet state energy of the phthalocyanines (< 94.00 KJ/mol). The palladated Pcs show high triplet state energy (> 94.00 KJ/mol) resulting in high singlet oxygen quantum yield.