Anion-Responsive Supramolecular Gels

Supramolecular gels that change their state or structure in response to anion stimuli have been highlighted. Only a few examples exist of such supramolecular gels, the structures and properties of which can be controlled and modulated by interactions with anions. To form anion‐responsive dimensionally‐controlled organized structures, the constituent low‐molecular‐weight gelator molecules must act as anion receptors by possessing one or more of van der Waals interaction units (aliphatic chains), stacking π planes, hydrogen‐bonding sites, and metal‐coordination units. This Concept focuses on the gelation and transition behaviors of amide‐ and urea‐based anion‐stimulated systems, metal‐coordinated systems, and novel acyclic π‐conjugated oligopyrroles that act as “molecular flippers.” Slick transformation: Supramolecular gels, as dimensionally controlled organized structures, consisting of anion receptors that can be tuned and modulated by the interactions between anions and binding sites or metal cations are discussed (see scheme).