The temperature dependent photoswitching of a classic diarylethene monitored by in situ X-ray diffraction.

Organic photochromic molecules including diarylethenes are of particular interest for their numerous potential applications including high-density optical data storage and light-activated switches. In this report, we examined the temperature dependence of the light-drive photocyclization reaction in a classic diarylethene. The steady-state populations were monitored spectroscopically and by temperature dependent in situ photocrystallography, the latter being the first reported example of this technique. The observed decrease in the steady-state population with decreasing temperature suggests this classic diarylethene possesses an excited-state potential energy surface topology similar to previously reported "inverted" diarylethenes.