lonic-Liquid-Functionalized Polyoxometalates for Heterogeneously Catalyzing the Aerobic Oxidation of Benzene to Phenol: Raising Efficacy through Specific Design

By combining nitrile-tethered pyridinium-based ionic liquid dication with the polyoxometalate anion of Keggin H5PMo10V2O40 (PMoV2) through precipitation in aqueous solution, an organicinorganic hybrid catalyst 1,1'-(butane-1,4-diyl)-bis(3-cyanopyridine)PMoV2 was prepared for heterogeneous hydroxylation of benzene to phenol with O-2 and ascorbic acid as the oxidant and reductant, respectively. The hybrid catalyst not only gave the high phenol yield of 13.0?% under the optimized reaction conditions, but also exhibited high potential for reusability. The catalyst and its analogue samples were characterized by elemental analysis, Fourier transform infrared spectroscopy, electron spin resonance spectroscopy, X-ray diffraction, scanning electron microscopy, and nitrogen adsorptiondesorption analysis. The structureactivity relationship is discussed according to the characterization and density functional theory calculation results.