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

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 S0 and S1 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 Osingle bondH bond and the twisted angle. It is predicted that TICT in S1 can facilitate ESPT initiated by intermolecular hydrogen-bond strengthening in the S1 state. The coupling of ESPT and TICT is energetically preferable