A study on the spectroscopy and photophysics of 4′-N,N-dimethylaminoflavone derivatives

Abstract The luminescence behavior of 4′-N,N-dimethylaminoflavone derivatives with different structures has been studied in different solvent conditions. Results show that the luminescence depends dramatically on the solvent polarity due to the solvent dependence of the compound conformation. The planar conformation is proved to be favourable for fluorescence emission. In addition, results of viscosity-dependent luminescence show that for compound 3 with the rigidized planar structure the luminescence behavior does not depend on the medium viscosity. In contrast, for compounds 1 and 2 the fluorescence quantum yields increase with increasing medium viscosity, indicating that the rotation relaxation process of the B benzene ring in the molecule is very important in the nonradiative decay process of excited molecules of these compounds.