Photophysical properties of some derivatives of 3-arylmethylene-1(3H)-isobenzofuranone: Indication of intermolecular hydrogen-bond formation in the singlet excited state

Abstract

The fluorescence behavior of some derivatives of 3-phenylmethylene-1(3H)-isobenzofuranone and 5-amino-3-phenylmethylene-1(3H)-isobenzofuranone in different media at room temperature and in frozen matrix at 77 K are reported. It is found, that in the cases of the amino substituted compounds at 293 K the dependencies of the fluorescence Franck–Condon transition energy and the fluorescence quantum yield on the ET(30) constant of the solvent, as well as the fluorescence decay curves, are strongly influenced by the proton donating ability of the solvent. These experimental results indicate formation of intermolecular hydrogen bonded solute–solvent complexes in the fluorescent excited state at room temperature in protic solvents. The effect of the substituents in the p-position of the phenyl ring in the investigated isobenzofuranones on the deactivation processes of their singlet excited state is discussed.