Photochemistry and photophysics of donor-acceptor-polyenes.: I:: all-trans-4-dimethylamino-4′-cyano-1,4-diphenylbutadiene (DCB)

Dimethylamino-cyano-diphenylbutadiene (DCB) has been investigated using photochemical and photophysical techniques. HPLC analysis enabled the separation of two photoisomers. Their absorption spectra and extinction coefficients were determined by combining the diode array spectra with the isosbestic points observed in photolysis. The forward and backward quantum yields of photoisomerization were determined. The quantum-chemical modelling of these spectra allowed for a tentative assignment of the photoisomers to the mono-cis isomers ct and tc. Fluorescence lifetimes and quantum yields allowed the conclusion of a negative solvatokinetic behaviour of the nonradiative decay. Catalyzed thermal isomerization of DCB was observed on reversed-phase chromatographic material. (C) 1999 Elsevier Science S.A. All rights reserved.