Synthesis and photochromic properties of a dithia-dithienylethenophane

The thermally irreversible photochromic compound dithia-dithienylethenophane was synthesized, which is the first example of a dithienylethene bridged with benzene ring and due to the fixation to the photoactive anti-conformation the quantum yield for the photocyclization reaction became higher than that of the corresponding nonbridged type dithienylethene.