SOLVATOFLUOROCHROMIN AND QUENCHING OF 3-(2'-AMINOTHIAZOLYL-4')-COUMARIN FLUORESCENCE IN POLAR MEDIA

Spectral luminescence characteristics of 3-(2'-aminothiazolyl-4')-coum arin (I) in 13 aprotic solvents of different polarity are studied, the dipole moment of the molecule studied in an excited state is determin ed. The matrix elements of the spin-orbital coupling tensor are calcul ated by quantum-chemical methods in the pi-approximation, the calculat ion results are used to assess the rate constants for intersystem cros sing and to predict the efficiency of this crossing at various relativ e positions of individual singlet and triplet energy levels of I in po lar solvents. An important contribution of the intersystem crossing be tween the pi pi-type levels to fluorescence quenching in organic lumin ophores in polar liquids is revealed.