Five diarylethene photochromic derivatives, the structures of which incorporate a central benzothiophene unit, a left-hand thiazole group, and a right-hand benzothiophene group, have been prepared. The compound with a thiazole unit with no substituent on the reaction-center carbon atom reveals an unprecedented transformation upon light irradiation. When the 4-position of thiazole is protected by a methyl group, the compounds show high photosensitivity and photochromic properties. In this case, light irradiation affords new compounds with [5]helicene structures featuring the highest redshifted absorption maxima reported to date.
Keywords: arylation; helical structures; isomerization; photochromism; substituent effects.
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