Electron-catalysed molecular recognition

Molecular recognition(1-4) and supramolecular assembly(5-8) cover a broad spectrum(9-11) of non-covalently orchestrated phenomena between molecules. Catalysis(12) of such processes, however, unlike that for the formation of covalent bonds, is limited to approaches(13-16) that rely on sophisticated catalyst design. Here we establish a simple and versatile strategy to facilitate molecular recognition by extending electron catalysis(17), which is widely applied(18-21) in synthetic covalent chemistry, into the realm of supramolecular non-covalent chemistry. As a proof of principle, we show that the formation of a trisradical complex(22) between a macrocyclic host and a dumbbell-shaped guest-a molecular recognition process that is kinetically forbidden under ambient conditions-can be accelerated substantially on the addition of catalytic amounts of a chemical electron source. It is, therefore, electrochemically possible to control(23) the molecular recognition temporally and produce a nearly arbitrary molar ratio between the substrates and complexes ranging between zero and the equilibrium value. Such kinetically stable supramolecular systems(24) are difficult to obtain precisely by other means. The use of the electron as a catalyst in molecular recognition will inspire chemists and biologists to explore strategies that can be used to fine-tune non-covalent events, control assembly at different length scales(25-27) and ultimately create new forms of complex matter(28-30).

Automated summary

Molecular recognition and supramolecular assembly are important areas of non-covalent phenomena. This study introduces a simple and versatile strategy to extend electron catalysis, widely used in synthetic covalent chemistry, into the field of supramolecular non-covalent chemistry. It demonstrates that the formation of a specific molecular complex can be accelerated and controlled by the addition of catalytic amounts of a chemical electron source.