Unusual behaviour in the excited state proton transfer of 1H-phenanthro[9,10-d]imidazole

Abstract

Absorption and fluorescence spectra of 1H-phenanthro[9,10-d]imidazole in different solvents and at different pH values have shown that the long wavelength bands are due to the transitions localised at the phenanthrene ring and the pyridine nitrogen atom is more acidic in S₁ than in S₀.