Oxovanadium(IV)-salophen covalently immobilized on silica-coated Fe₃O₄ nanoparticles: A magnetically recoverable nanocatalyst for the selective oxidation of sulfides

The current study introduces an approach toward the development of heterogeneous, magnetically recoverable oxovanadium(IV)-salophen complex to employ in the selective oxidation of sulfides using H2O2 as oxidant. A salophen ligand containing hydroxyl functional group was synthesized, which is conducive to successful, covalent immobilization of metal complex onto the silica-modified Fe3O4 magnetic nanoparticles (SMNPs). This type of metal anchoring is achieved through an intermolecular condensation reaction. The in-depth investigation on the catalyst (Fe3O4@SiO2@VO(salophen)) productivity and lifetime in the oxidation of a wide range of linear and aromatic sulfides is well represented and discussed. The use of the current catalyst in the selective oxidation of prototype substrate (methyl phenyl sulfide) resulted in an appreciable increase in the selectivity toward the desired sulfoxide (92%) and conversion rate (95%) compared with similar studies, reported to this day. Analytical techniques such as field emission scanning electron micrograph (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FT-IR), X-ray diffraction (XRD) analysis, and inductively coupled plasma optical emission spectrometer (ICP-OES) provided data on structural/compositional characterization of materials in catalyst preparation steps.