Computational design of photoswitchable anion receptors: Red-shifted and bistable di-ortho-fluoro di-ortho-chloro azobenzene derivatives

Photo-therapeutic applications require efficient photo-switchable anion receptor materials with high photoisomerization ratio, thermal stabilities, and anion binding affinities. Based on di-ortho-fluoro di-ortho-chloro azobenzene (dfdc-AB), a recently proposed photoswitch whose E -* Z isomerization can be triggered using irradiations in the bio-optical window, we designed a series of photoswitchable anion receptors with firstprinciples calculations. We demonstrated that, by modifying the 3- and 5-site of the azobenzene backbone of dfdc-AB using methoxyamide groups, the resulted dfdc-AB-OCH3 has nearly bistability, high E -* Z conversion in the visible region, and apparent difference in binding affinities for CH3CO2 at different isomers, indicating a promising photoswitchable anion receptor in photopharmacology.