prepared a new 1,2-bis(3-cyanothiophen-2-yl)perfluorocyclopentene with electro-withdrawing cyano groups at both reactive carbon atoms. Furthermore, we studied the substituent effects of the reactive carbon atoms on the photochromic properties of 1,2-bis(3-R-substituted thiophen-2-yl)perfluorocyclopentenederivatives by comparing the absorption wavelengths and quantum yields of the derivatives having R =
A bis(2-thienyl)perfluorocyclopentene having methoxy groups at both reactive carbon atoms was synthesized and the quantum yields of cyclization and cycloreversion reactions were found to be 0.29 and 0.27, respectively. Usual bis(3-thienyl)perfluorocyclopentenes with methoxy groups at both reactive carbon atoms show much lower cycloreversion quantum yields. The unusual large yield was explained by theoretical methods. Additionally the compound did not show any coloration in crystalline state upon UV irradiation, even though the distance between both reactive carbon atoms is less than 4 Å. The reason was discussed by using the crystallographic data.