Multi-step regulation of anion recognition by redox-active pseudocryptand

We synthesized an artificial redox-active Fe-pseudocryptand as an anion receptor to respond to electrochemical oxidation and reduction. Spectroscopic study and X-ray crystallography showed that the assembled urea chains and the isocyanuric platform generate an anion-binding cavity through favorable multiple hydrogen bonds and anion-π interactions. As the positive charge of the Fe center increases, the anion affinity is effectively increased due to an enhanced electrostatic interaction between the Fe atom and the anionic guest. This is the first efficient multi-step regulation of Cl⁻ selective anion recognition by the redox-active pseudocryptand.