Flash photolysis study of diaminopyridines

Abstract

The triplet—triplet absorption spectra of three diaminopyridines have been assigned from variable-temperature flash photolysis studies. In all cases the lowest triplet state is ππ* with a phosphorescence lifetime of about 2 s at 77 K in ethyl ether—pentane—ethyl alcohol. Complete neglect of differential overlap—configuration interaction calculations were performed to supplement the interpretation of the fluorescence and phosphorescence data and to provide a satisfactory correlation of the observed and predicted behavior of these molecules.