Substituent effect on the photochromic reactivity of bis(2-thienyl)perfluorocyclopentenes

Substituent effect on the photochromic reactivity of bis(2-thienyl)perfluorocyclopentenes was examined. Introduction of phenyl groups having electron-donating substituents on the para-position of the phenyl ring to the 5-position of the thiophene rings shifted the absorption bands of the open-ring isomers to longer wavelengths and reduced the quantum yield of the cyclization reactions. The substitution with p-(N,N-diethylamino)phenyl groups prohibited the cyclization reaction. The absorption spectra of the closed-ring isomers were not influenced by the substitution.