A Stable Polyoxometalate-Based Metal–Organic Framework as Highly Efficient Heterogeneous Catalyst for Oxidation of Alcohols

Abstract

A novel copper-containing 3D polyoxometalate-based metal-organic framework (POMOF), H[Cu₅^ΙCu^ΙΙ(pzc)₂(pz)_4.5{P₂W₁₈O₆₂}]·6H₂O (HENU-1, HENU = Henan University; Hpzc = pyrazine-2-carboxylic acid, pz = pyrazine), was successfully isolated by a one-step hydrothermal method. In this compound, the {P₂W₁₈} polyanion acts as a seven-connected linker bridging adjacent 2D double-layer networks, as well as a template to induce the formation of the desired 3D framework. Particularly, the pz ligands are generated from pzc ligands in situ during the reaction process. HENU-1 exhibits not only good stability in air but also tolerance to acidic and basic media. It was first employed as a highly efficient heterogeneous catalyst for the oxidation of 1-phenylethanol into acetophenone, which shows 97% yield using tert-butyl hydroperoxide as oxidant with a turnover frequency of up to 9690·h^-1, and was reused for at least five cycles without significant catalytic activity loss. No POM leaching or framework decomposition was observed in our study.