Magnetically recoverable graphene oxide supported Co@Fe 3 O 4 /L-dopa for C-C cross-coupling and oxidation reactions in aqueous medium

We report the synthesis of inexpensive and environmentally benign cobalt(0) nanoparticles on L-3,4-dihydroxyphenylalanine (L-dopa) functionalized and magnetite (Fe 3 O 4 ) grafted graphene oxide (Co@GO/Fe 3 O 4 /L-dopa) which was fully characterized with different techniques such as Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HR-TEM), X-Ray Photoelectron Spectroscopy (XPS), X-ray Powder Diffraction (XRD), Thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Vibrating Sample Magnetometer (VSM), Carbon Hydrogen Nitrogen (CHN) analysis, Energy Dispersive X-ray (EDX) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). Graphene oxide was used as the core material due to its mechanical, electrical and thermal properties. In order to avoid the cumbersome process of separation, magnetite nanoparticles were coated over the graphene oxide. After the successful preparation of graphene oxide based magnetic nanoparticles, L-dopa was grafted over Fe 3 O 4 nanoparticles so as to provide firm anchoring agent for cobalt nanoparticles. Finally, cobalt(0) nanoparticles were immobilized on the developed magnetic support. The catalytic efficiency of the synthesized catalyst was tested for Suzuki cross-coupling and oxidation reactions, usually carried out by precious and expensive second and third row transition metals; products were obtained in good to excellent yields. The synthesized catalyst represents an attractive alternative to conventional catalysts for Suzuki cross-coupling and oxidation reactions, and is recyclable up to five runs.