Synthesis, Structure, and Photochromic Properties of Dithia‐(dithienylethena)phane Derivatives

Abstract

Abstract Dithia‐(dithienylethena)phane derivatives, composed of dithienylethene moieties and benzene bridges, were synthesized by a coupling reaction of the corresponding bis(chloromethyl)benzene with bis(mercaptomethyl)dithienylethene under high‐dilution conditions. The products exhibit photochromic properties upon irradiation with ultraviolet and visible light. The photocyclization and cycloreversion quantum yields were determined, and a relationship between the photocyclization quantum yield and distance between the reactive carbon atoms of the phane derivatives established. The ortho isomer has a high efficiency in photocyclization due to its fixation in the photo‐active anti conformation and short distance between the two reactive carbon atoms. The thermal stability of these photochromic compounds has been studied and the ortho isomer found to show thermal irreversibility. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)