Fluorescence spectra of asymmetric diamines having primary and tertiary amino groups

Broad and asymmetric emission spectra were obtained with some saturated diamines which have a primary and a tertiary amino group in cyclohexane, diethyl ether and tetrahydrofuran. These spectra were resolved into three component bands. The shortest- and longest-wavelength bands were assigned to an excited tertiary amino group moiety and an exciplex formed between the excited tertiary amino group and the ground-state primary amino group. The middle-wavelength band was assigned to an excited primary amino group moiety formed through the exciplex. The enthalpy changes among three emitters were estimated from the temperature dependences of the intensity ratios of the emission bands. The solvent effect on the emission bands and the enthalpy changes are discussed.