In this paper, an effective and selective heterogeneous catalyst was produced by immobilization of manganese and cobalt Schiff base-complexes on Co magnetite nanoparticles (MNP). The catalysts Co@SiO2[(EtO)3Si–L3]/M (M ¼ Mn(III) and Co(II)) were synthesized using Co@SiO2 core–shell nanoparticles and amino-functionalized Co@SiO2. The Schiff base ligand Co@SiO2[(EtO)3Si–L3] was synthesized by reacting Co@SiO2 core–shell nanoparticles with 2-hydroxy 1-naphthaldehyde for the synthesis of Co@SiO2[(EtO)3Si–L3]/M. The catalysts were characterized by several techniques, such as FT-IR, TEM, XRD, TGA and VSM. The catalytic activities of the prepared catalysts were studied by oxidation of sulfides to the sulfoxides under different conditions. These catalysts can be easily recovered and reused in at least seven sequential cycles without considerable leaching and loss of reactivity.
