Calculations of the Absorption Spectrum of Chromone

Abstract

We have performed a theoretical investigation of the optical properties of the molecule chromone, using multireference perturbation theory (CASPT2) and time-dependent density functional theory (DFT) methods. The structure of the molecule was optimized at the DFT level and at the level of complete active space self-consistent field (CASSCF). In addition to vertical excitation energies, we have computed the lowest adiabatic 1A‘ transition energy, as well as transition probabilities for all singlet transitions to low-lying states. Using this data, we can assign the four observed ultraviolet absorption peaks of chromone. Finally, we address the question of the aromaticity of the heterocyclic ring in chromone, an issue which has recently received some attention.