Spectroscopy and photophysics of flavin-related compounds: 5-deaza-riboflavin

The properties of 5-deaza-riboflavin were characterized in solutions and in the solid state. Spectroscopic and photophysical data for the singlet state of the title compound in methanol are presented. Comparison of the emission spectrum in the solid state with the respective spectrum obtained in solution reflects the solvent influence. Theoretical studies concerning singlet–singlet and triplet–triplet excitation energies were carried out using TD-DFT calculations. All the observable singlet–singlet transitions were characterized as π,π* type. The title compound was shown to be an efficient sensitizer of the production of singlet oxygen (ϕΔ=0.33). We also present 1H and 13C NMR spectra.