Photochemical Properties of 1-(9-Phehanthryl)-2-(2-Quinolyl)ethylene

Abstract

Spectral and photochemical properties of 1-(9-phehanthryl)-2-(2-quinolyl)ethylene (9Ph2QE) in neutral and protonated forms have been investigated. It has been found that both isomers of 9Ph2QE are photoactive. The quantum yield of trans–cis photoisomerization (ϕ_tc = 0.47) in the neutral form is typical of the diabatic photoisomerization; on passing to the protonated form, ϕ_tc increases up to 0.70. Thus, the double annelation of the 2-styrylquinoline phenyl group to form 9Ph2QE makes it possible to conserve the α-effect, which consists in an increase in the quantum yield to ϕ_tc > 0.5 on passing from the neutral to protonated form, whereas the effect disappears for other types of annelation (naphthylquinolylethylenes, 1-(9-anthryl)-2-(2-quinolyl)ethylene).