Laser-flash photolysis of dialkylbenzodipyridoporphyrazines

In the course of a fundamental study of photosensitizers for photodynamic therapy of cancer, a non-peripheral substituted phthalocyanine analogue, zinc bis(1,4-didecylbenzo)bis(3,4-pyrido)porphyrazine and its position isomers were examined to measure their photoexcited triplet state lifetimes in poly(methyl methacrylate) film using laser-flash photolysis. The isomer mixture of zinc bis(1,4-didecylbenzo)bis(3,4-pyrido)porphyrazine showed the most intense absorption in the 660-710 nm region, and the longer triplet state lifetime. The lowest symmetry isomer of zinc bis(1,4-didecylbenzo)bis(3,4-pyrido)porphyrazine was found to have the longest triplet state lifetime when all isomers were separated. The compound is proposed to be suitable for use as a photosensitizer for photodynamic therapy of cancer.