Fluorescence and picosecond induced absorption from the lowest singlet excited states of quercetin in solutions and polymer films

摘要: The spectroscopic and photophysical properties of the biologically important plant antioxidant quercetin in organic solvents, polymer films polyvinyl alcohol, a buffer solution at pH 7.0 are studied by stationary luminescence femtosecond laser spectroscopy room temperature 77 K. large magnitude dipole moment molecule excited Franck–Condon state μ e FC = 52.8 C m indicates dipolar nature this state. transient induced absorption spectra S 1→S n all solvents characterized short-wave band λ abs max 460 nm with exponential decay times range 10.0–20.0 ps. In entire spectral >100 ps, no residual was observed that could be attributed to triplet–triplet transitions Т 1 → k quercetin. polar two-band fluorescence also recorded temperature, which is due initial enol form (~415 nm) its keto transferred proton (550 nm). absent nonpolar 2-methyltetrahydrofuran (2-MTHF). excitation exhibit low dependence on wavelength detection, may related solvation conformational changes molecule. Decreasing glassy-like freezing ethanol 2-MTHF K leads strong increase intensity (by factor ~100) both bands. energy circuits for transfer process proposed depending polarity medium. main channel exchange electronic internal conversion ⇝ 0, transfer.