Thiophene-S,S-dioxidized diarylethenes for light-starting irreversible thermosensors that can detect a rise in heat at low temperature

Abstract

Diarylethenes having trimethylsilyl and triethylsilyl groups at the reactive positions and their S,S-dioxidized diarylethenes were synthesized and their optical and thermal properties were investigated. Upon irradiation with ultraviolet light, the diarylethenes and thiophene-S,S-dioxidized diarylethenes underwent photochromic reactions from the colourless open-ring isomer to the coloured closed-ring isomer. The photogenerated closed-ring isomers were found to undergo thermal bleaching reactions to produce colourless byproducts. In particular, the thiophene-S,S-dioxidized diarylethene having a triethylsilyl group at the reactive positions underwent the thermal bleaching reaction even at −40 °C. Such materials could be used as light-starting irreversible thermosensors that can detect a rise in heat at low temperature.