Fast T‑Type Photochromic Crystals of Diarylbenzene

Photochromic molecules are of great interest as light-driven molecular switches in research fields of material and life sciences. In particular, fast T-type photochromic molecules with half-life times of the thermal back reaction (t1/2) on the order of milliseconds can change not only their color but also their physicochemical properties only under photoirradiation. Herein, we report fast T-type photochromic crystals with the t1/2 on the order of milliseconds composed of a diarylbenzene by utilizing intramolecular CH–N hydrogen bonding interactions. Our results would lead to novel photoresponsive crystalline materials whose color and physicochemical properties can be modulated only under photoirradiation.