Immobilization and application of catalysts on magnetic carbon coated metal nanoparticles

The aim of this work was to develop a new noncovalent immobilization method on magnetic carbon coated metal nanoparticles. The noncovalent immobilization of catalysts offers promising features that the covalent linkage is lacking. For example, it is possible to perform reactions in a homogeneous way by desorbing the catalyst during the reaction at elevated temperature or to renew the catalyst loading after a few runs. pp-interactions between the aromatic surfaces of magnetic carbon coated metal nanoparticles and pyrene moieties create sufficiently strong forces to bind the catalysts in aqueous media to the surface of the particles and to recover them by magnetic decantation. In comparison to covalent linkage on the nanobeads almost twice as much loading could be achieved. The in this way immobilized catalysts were tested in the hydroxycarbonylation of aryl halides with carbon monoxide in water at elevated temperatures and the proline catalyzed aldol reaction in aqueous environment