Azophotoswitches containing thiazole, isothiazole, thiadiazole, and isothiadiazole.

We report a novel class of azophotoswitches incorporating various five-membered heteroaryl units such as thiazole, isothiazole, thiadiazole, and isothiadiazole. These azophotoswitches were developed through an initial screening of 24 compounds using DFT calculations to identify those with the wavelength of maximum absorption () at a long wavelength. Subsequently, eight selected azophotoswitches were synthesized. Compounds containing both thiazole and isothiazole moieties showed relatively long compared to the other synthesized compounds. These azophotoswitches exhibited reversible isomerization under visible light irradiation at 430 nm, 450 nm, 470 nm ( to ) and 525 nm ( to ). Analysis of the X-ray crystal structures of the isomer of phenylazo[1,3,4-thiadiazole] exhibited a unique orthogonal geometry.