Molecular recognition and assembly are ubiquitous in both chemistry and biology, leading to broad applications in a variety of research areas. In analogy with the success that catalysis has experienced in promoting chemical reactions, the advent of appropriate catalysts to control molecular recognition will undoubtedly enrich the repertoire of noncovalent syntheses. The examples of catalytic assembly, however, are scarce and rely heavily on sophisticated catalyst design. Here, we establish a simple and versatile strategy to facilitate molecular recognition by extending <i>electron catalysis</i>—widely applied in synthetic covalent chemistry—into the realm of supramolecular noncovalent chemistry. The formation of a host–guest trisradical complex, a molecular recognition process that is kinetically forbidden under ambient conditions, is accelerated dramatically by introducing a small number of electrons. Mechanistic studies, involving the identification of a key intermediate complex, reveal that the electron, rather than any elaborately designed molecule, serves as the actual catalyst. Different chemical electron sources with sufficient reducing ability, regardless of their structures, prove to be effective in initiating molecular recognition. Additionally, electrochemically controlled molecular recognition is also achieved by electrolysis in an undivided cell. This protocol, featuring the temporal control of supramolecular events, has enabled the production of an almost arbitrary distribution between substrates and complexes that is kinetically stable and cannot readily be obtained by other means.

Electron-catalyzed molecular recognition

ACS Spring 2022

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