The conformational, electronic and spectral properties of chalcones: A density functional theory study

The ground-state geometries and electronic spectra of trans-chalcone and its derivatives have been studied with the density functional theory (DFT) and time-dependent density functional theory (TD-DFT). A wide panel of theoretical methods has been used, with various basis sets and DFT functionals, to assess a level of theory that would lead to converged excitation energies. Solvent effects on the excitation energies were computed through the integral equation formalism of the polarizable continuum model (IEFPCM). It turns out that PCM-TD-PBE1PBE/6-31G//PBE1PBE /6-31G(d) approach provides reliable λmax. The calculated absorption spectral properties are in good agreement with the experimental results. The results suggest the assignments for the lowest five electronic transitions observed experimentally for trans-(s-cis)-chalcone in solution. Calculated substitution shifts for trans-(s-cis)-chalcone derivatives are in qualitatively agreement with experimental data.