Emission properties of gossypol in solution

Abstract

Steady-state emission properties of gossypol in acetonitrile at room temperature have been studied using a HPLC system equipped with a specially improved highly sensitive fluorescence detector ( Φ F⩾10 −7). The fluorescence lifetimes ( τ) have been determined using a time-correlated single photon counting system. At room temperature gossypol shows weak fluorescence with the overall quantum yield of Φ F=5×10 −5. On the basis of a comparison of the excitation emission spectra with the absorption spectrum and the radiative properties of gossypol, the origin of gossypol fluorescence from two tautomeric forms: aldehyde in S 1 (n, π ∗) (τ=300 ps) and S 2 ( π, π ∗) (τ=10 ps) and lactol in S 1 (n, π ∗) (τ=18 ps) state was suggested.