Photocyclization of trans-1-(1'-naphthyl)-2-(3-hydroxyphenyl)ethene: evidence for adiabatic 1trans-->1cis photoisomerization

The photochemistry of trans- and cis-1-(1'-naphthyl)-2-(3-hydroxyphenyl)ethene in cyclohexane and acetonitrile was examined. In cyclohexane fluorescence is the main deactivation channel for the 1trans* isomer while photocyclization is the main reaction of the 1cis* isomer. The weighty formation of hydroxychrysene following one photon absorption by the trans isomer furnished evidence of an adiabatic 1trans*-->1cis* isomerization. The photoreactivity data in acetonitrile indicated the influence of solvent polarity on the shape of the excited state surface.