Electronic spectroscopy and photochromic mechanism of bis-Schiff bases, N, N'-bis(2-hydroxy-1-naphthylidene)-1,4-phenyldiamine

Abstract

The steady state and transient state absorption spectra and fluorescence spectra of N, Ń-bis(2-hydroxy-1-naphthylidene)-1, 4-phenyldiamine (BNP) in cyclohexane and acetonitrile were determined. The photochromic mechanism was discussed. In nonpolar solvents, BNP exists mainly in the enol form and has the absorption maximum in the UV region. In polar solvents, however, both the enol and proton transfer tautomer are formed, but the former is the main one. Fluorescence emissions result from the excited state of proton transfer product.