Application of polar solvent effects in absorption spectra for determination of lowest electron-excited states of phthalide

摘要： The optical absorption spectra of phthalide in polar (methanol) and nonpolar (n-hexane) solvents are recorded. The electronic phthalide spectrum was calculated by TDDFT B3LYP/6-311+G(d, p) using the polarisable continuum model. Based on an analysis of calculation data and the displacement of absorption bands in a polar solvent, it was established that the absorption bands of phthalide at energies of 3.51 and 3.96 eV correspond to singlet-triplet transitions to the T1 and T2 states, respectively.