Preparation of Functionalized Carbon‐Coated Cobalt Nanoparticles with Sulfonated Arene Derivatives, a Study on Surface Functionalization and Stability

The functionalization of magnetic nanoparticles has been an important field in the last decade due to the versatile applications in catalysis and biomedicine. Generally, a high degree of functionalities on the surface of the nanoparticles is desired. In this study, covalent functionalization of various aromatic sulfonic acids on carbon‐coated cobalt nanoparticles are investigated on surface functionalization yield and stability. The nanoparticles are prepared via covalent linkage of an in situ generated diazonium on the graphene‐like surface. Adsorption and wash experiments were performed to confirm a covalent bonding of the naphthalene derivatives on the nanoparticle surface. With an increased number of sulfonic acid groups on the aromatic compound a significantly lower loading is observed on the corresponding functionalized nanoparticles. This can be counteracted by a change of nitrite species. With this method, nanoparticles with a high number of sulfonic acid groups can be produced. Sulfonated magnetic nanoparticles may be used as catalysts or potentially as anticoagulants in blood. To achieve high activities, a high loading of sulfonate groups is desired. In this article we investigated the maximization of covalent functionalized sulfonate groups on the surface of carbon‐coated cobalt nanoparticles, assessed their stability and investigated the activity towards ring opening polymerization of glycidol.