The vibronic absorption spectra and electronic states of proflavine in aqueous solution

Abstract

The time-dependent density functional theory (TD-DFT) was used to calculate vibronic absorption spectra of proflavine (PF) in an aqueous solution, which are in good agreement with the experiment. The protonated and neutral forms of the dye have been investigated. The results of calculations using various functionals and basis sets have been analyzed. The best agreement with experiment was given by the X3LYP/6-31G(d,p) theory level. An insignificant photoinduced electron transfer was found in the central ring of the chromophore. According to our calculations, the vibronic coupling and the Boltzmann distribution play a significant role in the absorption spectra of the PF.