Electronic structure and spectral properties of selected trimethyl-alloxazines: Combined experimental and DFT study

Electronic structure and S0-Si, T1-Ti, and S0-Ti transition energies and oscillator strengths were calculated using the TD-DFT method for a series of trimethyl substituted alloxazines. The general energy diagram of the excited states predicted by the calculations is generally the same in these and in other alloxazines, with the two lowest close-lying n, π∗ and π, π∗ singlet excited states, determining the photophysical properties, being isoenergetic in most cases. The theoretical predictions are compared to the experimentally determined spectral and photophysical properties.