Influence of solvent on the electronic absorption and fluorescence spectra of trans-1-(4-NN-dimethylaminophenyl)-2-nitroethylene

Abstract

The electronic absorption and fluorescence spectra of the title compound (I) are reported for a wide range of solvents. Spectral assignments are made with the aid of PPP–SCF–MO (with Cl) calculations and the nature of the lowest energy, intramolecular, charge-transfer transition is discussed. Temperature- and solvent-induced shifts of the fluorescence band of (I) are interpreted. The induction of fluorescence emission and subsequent quenching on addition of polar solvents to cyclohexane solutions of (I) are discussed in terms of solvent effects on the juxtaposition of the n–π* and π–π* singlet and triplet energy levels.