Preparation of Functionalized Superparamagnetic Fe3O4@Dopamine@Metal Ions (Cu+,Ru2+) Nanocomposites and its Catalytic Applications

In this work, we present a simple method for the synthesis of metal ions stabilized on dopamine modified iron oxide nanoparticles (Fe₃O₄@DA@M^x+) and their catalytic applications in important organic transformation reactions. Two different metal ions (Cu⁺¹ and Ru²⁺) are studied in this work. It is observed that both synthesized Fe₃O₄@DA@Cu⁺ and Fe₃O₄@DA@Ru²⁺ can effortlessly be separated from the reaction medium by positioning an external magnetic field. Dopamine, which is used as an anchor between Fe₃O₄ and metal ions, increases the solubility of catalyst in reaction medium and prevents leaching of metal ions from the catalyst surface. Here Fe₃O₄@DA@Cu⁺ is used in the synthesis of 1,2,3-triazole derivatives via azide-alkyne cycloaddition reactions and Fe₃O₄@DA@Ru²⁺ is used for transfer hydrogenation reaction of various aryl ketones. The Fe₃O₄@DA@M^x+ nanocomposite is characterized via powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), atomic absorption spectroscopy (AAS), thermogravimetric analysis (TGA) and vibrating-sample magnetometer (VSM). The Fe₃O₄@DA@M^x+ catalytic systems can be reused in the reaction mixture up to five times without significant loss in their catalytic activity.