Complexing and photoprocesses in a PRODAN molecule

The effect of hydrogen bond on the spectral-luminescent properties of the PRODAN molecule — water complexes is studied. Quantum chemical calculations are performed for the ground and fluorescent equilibrium states of a free PRODAN molecule and its complexes with H₃O⁺. It is shown that significant changes occur in the geometry of the molecule in the fluorescent state. To describe the fluorescent state, account was taken of the changes in the electron density (population) on the bonds and atoms in transition of the molecule to an excited state. The rate constants of radiative and nonradiative processes and quantum yields of fluorescence are calculated for the PRODAN molecule and its complexes in water. A significant shift of the fluorescent bands (sensitivity to a solvent) in transition of the molecule from cyclohexane to water is accounted for.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 71–75, November, 2004