Photo-controllable binding and release of HP₂O₇^3- using an azobenzene based smart macrocycle

Herein, we describe the design and synthesis of an unusual azobenzene-bearing macrocycle 1, whose trans isomer was found able to 100% transform into its cis configuration under photoirradiation, for selectively recognizing HP2O73- with reversibly photo-controllable binding and release properties.