Triplet excited state characters and photosensitization mechanisms of α-terthienyl: A theoretical study

The triplet excited (T1) state characters of α-terthienyl (α-T) have been investigated using density functional theory calculations, based on which, its photosensitization mechanisms were explored. Primarily, the direct oxidation to the DNA bases by the T1 state α-T through the electron transfer is not thermodynamically feasible. Secondly, 1O2 can be photogenerated both in benzene and water through the direct energy transfer from the T1 state α-T to 3O2, while O 2 - can only be formed in water through the electron transfer from the T1 state α-T or α-T− to 3O2.