Absorption spectra and photoreactivity of p-aminobenzophenone by time-dependent density functional theory

The absorption spectral properties of para-aminobenzophenone (p-ABP) were investigated in gas phase and in solution by time-dependent density functional theory. Calculations suggest that the singlet states vary greatly with the solvent polarities. In various polar solvents, including acetonitrile, methanol, ethanol, dimethyl sulfoxide, and dimethyl formamide, the excited S-1 states with charge transfer character result from pi ->pi* transitions. However, in nonpolar solvents, cyclohexane, and benzene, the S-1 states are the result of n ->pi* transitions related to local excitation in the carbonyl group. The excited T-1 states were calculated to have pi pi* character in various solvents. From the variation of the calculated excited states, the band due to pi ->pi* transition undergoes a redshift with an increase in solvent polarity, while the band due to n ->pi* transition undergoes a blueshift with an increase in solvent polarity. In addition, the triplet yields and the photoreactivities of p-ABP in various solvents are discussed.