Effects of Amino Substitution on the Excited State Hydrogen Transfer in Phenol: A TDDFT Study

When isolated phenol or a small phenol-solvent cluster is excited to the S1 state of ππ* character, the hydrogen atom of the hydroxyl group dissociates via a πσ* state that is repulsive along the O-H bond. We computationally investigated the substitution effects of an amino group on the excited state hydrogen transfer reaction of phenol. The time-dependent density functional theory (TDDFT) with B3LYP functional was employed to calculate the potential energy profiles of the ππ* and the πσ* excited states along the O-H coordinate, together with the orbital shape at each point, as the position of the substituent was varied. It was found that the amino substitution has an effect of lowering the πσ* state and enhancing the excited state hydrogen transfer reaction. KCI Citation Count: 3