Photophysics of pseudoazulenes: 7-azaindole derivatives

Abstract

Three pseudoazulenes derived from 7-azaindole reveal photophysical properties characteristic of this class of compounds: strongly temperature-dependent S₁ → S₀ fluorescence, weak phosphorescence, very small S₁—T₁ splitting, decrease in dipole moment on excitation to S₁ (ππ*) and S₂(ππ*) states and dimerization at low temperatures in non-polar solvents. Photoacoustic studies show that internal conversion is the dominant channel for the deactivation of the lowest excited singlet state.