Catalytic electron drives host-guest recognition

Electron injection is demonstrated to trigger electrocatalytic chain reactions capable of releasing a solvent molecule and forming a redox active guest molecule. One-electron reduction of a hydroxy anthrone derivative (AQH-CH2CN) results in the formation of an anthraquinone radical anion (AQ(-)) and acetonitrile (CH3CN). The resulting fragment of AQ(-) exhibits high stability under mild reducing conditions, and it has enough reducing power to reduce the reactant of AQH-CH2CN. Hence, subsequent electron transfer from AQ(-) to AQH-CH2CN yields the secondary AQ(-) and CH3CN, while the initial AQ(-) is subsequently oxidized to AQ. Overall, the reactants of AQH-CH2CN are completely converted into AQ and CH3CN in sustainable electrocatalytic chain reactions. These electrocatalytic chain reactions are mild and sustainable, successfully achieving catalytic electron-triggered charge-transfer (CT) complex formation. Reactant AQH-CH2CN is non-planar, making it unsuitable for CT interaction with an electron donor host compound (U(H)Ant(2)) bearing parallel anthracene tweezers. However, conversion of AQH-CH2CN to planar electron acceptor AQ by the electrocatalytic chain reactions turns on CT interaction, generating a host CT complex with U(H)Ant(2) (AQ subset of U(H)Ant(2)). Therefore, sustainable electrocatalytic chain reactions can control CT interactions using only a catalytic amount of electrons, ultimately affording a one-electron switch associated with catalytic electron-triggered turn-on molecular recognition.

Automated summary

Electron injection triggers sustainable electrocatalytic chain reactions, releasing solvent molecules and forming redox active guest molecules. One-electron reduction produces AQ(-), which is stable and powerful enough to reduce AQH-CH2CN, resulting in the formation of AQ and CH3CN. These mild and sustainable electrocatalytic chain reactions control charge-transfer complex formation, achieving molecular recognition with a catalytic electron-triggered switch.