Synergized Molecular Oxygen Activation in an Enzyme-Mimicking Metal-Organic Framework for Boosted C-H Bond Oxidation

Metal-organic frameworks (MOFs) have experienced significant progress and advancement in recent decades due to the multifarious modifications and functionalization of their inherent structures. However, the development of synergistic all-in-one MOF catalysts with functionalized organic linkers and metal nodes has posed formidable challenges. Here we construct an isostructural MOF, TJU-101-NHPI, using traditional Cu(II) paddle-wheel nodes as catalytic open metal sites (OMSs) and N-hydroxyphthalimide (NHPI) covalently embedded ligands as organocatalytic sites (OCSs) in spatial proximity. The TJU-101-NHPI catalyst, in combination with the cocatalyst t-butyl nitrite, can overcome the longstanding paradox to selectively oxidize primary alcohols to aldehydes or acids in a specific time-dependent manner. Moreover, the single TJU-101-NHPI MOF can directly activate O₂ to oxidize alkylarenes, resembling biomimetic enzymatic oxidation. The established catalytic systems use O₂ as the exclusive oxidant and yield H₂O as the sole byproduct, achieving nearly complete conversion and 100% selectivity in the majority of the oxidations (62 examples). Control experiments and computational studies reveal that the synergistic activation of molecular oxygen and facilitated hydrogen atom transfer (HAT) between the OMSs and the OCSs lead to the generation of critical phthalimido N-oxyl radicals on the pore surface, thereby boosting the oxidation under mild conditions. This research offers a new concept of leveraging MOF organic linkers as cofactors and inorganic nodes as metal sites to mimic enzymes for superior catalysis. © 2024 American Chemical Society.