Photoisomerization of (E)-1-(2-naphthyl)-2-pyrazin-2-ylethylene

Abstract

The fluorescence quantum yield of (E)-1-(2-naphthyl)-2-pyrazin-2-ylethylene (2-NPyE) is very low compared with 2-styrylnaphthalene (2-StN) due to very rapid radiationless decay processes and is sensitive to solvent polarity. The E→Z photoisomerization proceeds through both the singlet and triplet manifolds with relatively low quantum yields at room temperature. The singlet mechanism is favoured in polar solvents due to the decrease in intersystem-crossing efficiency with increasing solvent polarity.