Theoretical investigation on the triplet excited state properties of the porphyrin-related photosensitizers and the implications in illustrating their photosensitization mechanisms

In this communication, time-dependent density functional theory (TD-DFT) calculations are employed to investigate the triplet excited state properties of porphyrin-related photosensitizers, including free base porphyrin (FBP), free base chlorine (FBC) and porphyrazine (PZ), based on which, the photosensitization mechanisms of the three molecules have been explored. It was revealed that the three photosensitizers can photogenerate O-1(2) through direct energy transfer between T-1 state photosensitizers and O-3(2) both in benzene and water, while the photosensitizers can give birth to O-2(center dot-) only in aqueous solution and the O-2(center dot-)-generating pathways are different among the three molecules. (C) 2008 Elsevier B.V. All rights reserved.