Bioinspired Ion Recognition in Hexanuclear Copper Pyrazolate Metallacycles

The chemistry of anion‐encapsulation assemblies in copper pyrazolates is reminiscent of the work on the halide‐ and chalcogenide‐centered cubic copper(I) dithiolates. Great efforts have been made to determine the relationship between the design of the ligands, reaction conditions, and the structure of the metallacycles. Fine‐tuning the substituent on the pyrazole ligand and controlling the reaction stoichiometry has led to the synthesis of cages, crowns, and anticrowns. These metallacycles are composed of six copper atoms interlinked by the same number of pyrazolate ligands and encapsulate an anion in the cavity. The synthesis of copper metallacycles provides artificial systems for the bioinspired mimicry of the functions performed by the natural enzymes. Halide‐centered hexanuclear copper metallacycles mimic the artificial anion‐recognition agents.