Photodegradation Mechanism of Photochromic Diarylethene Derivatives

Abstract

Degradation mechanism of 1, 2-bis(2, 4, 5-trimethyl-3 -thienyl)-1, 2-dicyanoethene (TECN)was studied by product analysis. When TECN was irradiated in dichloromethane with 420nm light, the closed-ring isomer with absorption maximum at 520 nm was the sole product. O n the other hand, when irradiated with 370 nm light, oxygenated products were detected. Photogeneration of such products, possibly endo-peroxide moieties on thiophene rings, caused the degradation of TECN.