Hydroxo Iron(III) Sites in a Metal–Organic Framework: Proton-Coupled Electron Transfer and Catalytic Oxidation of Alcohol with Molecular Oxygen

Metalloenzymes are powerful biocatalysts that can catalyze
particular chemical reactions with high activity, selectivity, and
specificity under mild conditions. Metal–organic frameworks
(MOFs) composed of metal ions or metal clusters and organic ligands
with defined cavities have the potential to impart enzyme-like catalytic
activity and mimic metalloenzymes. Here, a new metal–organic
framework implanted with hydroxo iron­(III) sites with the structural
and reactivity characteristics of iron-containing lipoxygenases is
reported. Similar to lipoxygenases, the hydrogen atoms and electrons
of the substrate can transfer to the hydroxo iron­(III) sites, showing
typical proton-coupled electron transfer behavior. In the reactivity
mimicking biology system, similar to alcohol oxidase, the material
also catalyses the oxidation of alcohol into aldehyde by using O2 with a high yield and 100% selectivity under mild conditions,
without the use of a radical cocatalyst or photoexcitation. These
results provide strong evidence for the high structural fidelity of
enzymatically active sites in MOF materials, verifying that MOFs provide
an ideal platform for designing biomimetic heterogeneous catalysts
with high conversion efficiency and product selectivity.