Photoinduced coupled twisted intramolecular charge transfer and excited-state proton transfer via intermolecular hydrogen bonding: a DFT/TD-DFT study

Abstract We discuss theoretically the geometric and electronic structure properties of the thiazolidinedione derivative A and its hydrogen-bonded complex in dimethylformamide (DMF) solution in the S 0 and S 1 states. To gain insight into the photoinduced coupled excited-state proton transfer (ESPT) and twisted intramolecular charge transfer (TICT) associated with intermolecular hydrogen bonding, the potential energy profiles are provided along the O H bond and the twisted angle. It is predicted that TICT in S 1 can facilitate ESPT initiated by intermolecular hydrogen-bond strengthening in the S 1 state. The coupling of ESPT and TICT is energetically preferable.