Electrostatically-enriched Lithium Cations Catalyze Biomimetic Aerobic Oxygenation

Enzymes often involve short-range electrostatic interactions in the deliberate microenvironment for accelerating the catalysis. Comparatively, electrostatic interactions from ions in solutions are mostly shielded by solvent or counter-ion shells, creating negligible catalytic effects. Herein, we discovered that the Li+ cations electrostatically accumulated on negatively-charged carboxylated carbon nanotubes could create strong interactions with in-situ formed peroxide anion (OOH-) intermediates from O2 reduction, forming an active side-on Li+-OOH- complex. This complex reduces the O2-reduction energy barrier and increases the nucleophilicity, expediting the aerobic oxygenation of ketones. Aside from trapping active intermediates, excessive Li+ cations also attract the surrounding water dipoles to prevent from quenching the active Li+-OOH- complex, highly mimicking the Baeyer Villiger monooxygenase (BVMO). By using probe-assisted quantitative methods, we demonstrated the unique under-coordinative characteristics of interfacial Li+ with an order of magnitude higher concentration than the bulk solution, providing essential clues about the intrinsic discrepancy between electrocatalytic and thermocatalytic reactivities.