The merger of a metal-organic framework and an electron-proton transfer mediator for photocatalytic selective aerobic oxidation of amines

Metal-organic frameworks (MOFs) present a multifaceted avenue for visible light photocatalysis and are candidates for environmental applications, in which electron and proton transfers are crucial. To date, the photocatalytic activity of MOFs has been attempted, but with inherent limitations against formidable redox conditions. This can be addressed by adopting an electron-proton transfer mediator to mediate the redox processes over a MOF photocatalyst. To achieve this goal, an electron-proton transfer mediator, HOOC-TEMPO (4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl), is envisioned to steer the selective oxidation of amines over a pyrene-based MOF NU-1000. There are abundant terminal hydroxyl groups of Zr-oxo cluster within the mesoporous channels of NU-1000. Supported by density functional theory calculations, the bidentate chelation of HOOC-TEMPO onto NU-1000 by reacting with the hydroxyl groups is the most feasible mode of adsorption. The optoelectronic properties of NU-1000 can be notably improved by the facile and dynamic adsorption of HOOC-TEMPO. Distinctly, 1 mol