A TD-DFT study on triplet excited-state properties of curcumin and its implications in elucidating the photosensitizing mechanisms of the pigment

In this Letter, we present time-dependent density functional theory (TD-DFT)-derived triplet state properties of curcumin in vacuum, benzene and DMSO. Accordingly, the photosensitizing mechanisms of curcumin are explained. It is revealed that in benzene and DMSO, excited curcumin can react with O2 to generate 1O2 and O2- through energy transfer and electron transfer, however, the O2--generating pathways are different in both solvents. This indicates the potential of TD-DFT in determining the excited-state properties of pigments, which is of significance in getting a deeper insight into the photodynamic mechanisms of photosensitizers.