RADIATIONLESS DEACTIVATION OF 5-AMINO-2-ARYLINDAN-1,3-DIONES VIA INTERMOLECULAR HYDROGEN-BONDS

Steady-state and dynamic photophysical characteristics of a number of 4- and 5-amino-2-phenylindan-1,3-dione derivatives have been studied a t 293 and 77 K in solvents of widely different polarity and hydrogen-b onding ability. The observed changes of the fluorescence Franck-Condon transition energy, and of the fluorescence quantum yields and the sin glet lifetimes, as well as the solvent deuterium-isotope effect, indic ate the formation of intermolecular hydrogen bonds in the excited stat e with protic solvents for the 5-amino compounds at room temperature.