Thermal bleaching reactions of photochromic diarylethenes with thiophene-S,S-dioxide for a light-starting irreversible thermosensor.

Thiophene-S,S-dioxidized diarylethenes introducing bulky substituents at the reactive positions were newly synthesized. The diarylethenes showed reversible photochromism, whereas the photocycloreversion reaction was suppressed by thiophene-oxidation. The diarylethene closed-ring isomers having secondary alkyl groups at the reactive positions were found to undergo thermal bleaching reactions which produce at least three types of byproducts. Such materials could find application as light-starting irreversible thermosensors.