Picosecond Fluorescence Lifetimes of Anthraquinone Derivatives. Radiationless Deactivation via Intra- and Intermolecular Hydrogen Bonds

Article abstract of DOI:10.1021/j100213a024

Radiationless deactivations from the S₁(¹CT) states of seven 1- and 2-substituted aminoanthraquinones were investigated by measuring picosecond fluorescence lifetimes and fluorescence quantum yields in benzene, acetonitrile, and ethanol.The S₁(¹CT) states of all derivatives were largely deactivated in ethanol.Deuterium isotope effects of the solvents on the nonradiative rate constants k_nr(in EtOH)/k_nr(in EtOD) = 9.0 (1-NH2 (2)), 2.1 (2-NH2 (5)), and 1.7 (2-piperidino (7)) were observed.The fluorescence quantum yield in ethanol was not affected by temperature (278-343 K).In benzene the excited 1-aminoanthraquinones were deacvated faster than 2-aminoanthraquinones.These observations were interpreted in terms of the radiationless deactivations od S₁(¹CT) through the intra- and intermolecular hydrogen bonds.