Controlling binding affinities for anions by a photoswitchable foldamer.

A photoswitchable foldamer containing an azobenzene and phenyl-1,2,3-triazole motif was found to show photochemical/dark isomerization in a controllable and reversible manner in both the absence and presence of anions. The transformation in conformation of the foldamer leads to changes in binding affinities for anions to a certain extent that depends on the size and the geometrical shape of the anions.