Dynamic mechanostereochemical switching of a co-conformationally flexible [2]catenane controlled by specific ionic guests

Responsive synthetic receptors for adaptive recognition of different ionic guests in a competitive environment are valuable molecular tools for not only ion sensing and transport, but also the development of ion-responsive smart materials and related technologies. By virtue of the mechanical chelation and ability to undergo large-amplitude co-conformational changes, described herein is the discovery of a chameleon-like [2]catenane that selectively binds copper(I) or sulfate ions and its associated co-conformational mechanostereochemical switching. This work highlights not only the advantages and versatility of catenane as a molecular skeleton in receptor design, but also its potential in constructing complex responsive systems with multiple inputs and outputs. By virtue of the rotational motions of interlocked macrocycles, the authors describe a chameleon-like catenane host that can adjust its co-conformation for selective binding to copper(I) or sulfate ion. While the cationic copper(I) complex is achiral, the interlocked rings in the catenane host rotate and re-orient into a chiral co-conformation upon forming the anionic sulfate complex.