A green synthesis of biaryls in water catalyzed by palladium nanoparticles immobilized on N-amidinoglycine-functionalized iron oxide nanoparticles

Fe₃O₄ nanoparticles were prepared by co-precipitation and coated with SiO₂ following the Stöber process. N-Amidinoglycine amino acid was then covalently connected to provide an excellent ligand for the immobilization of Pd nanoparticles. The resulting material was characterized by FE-SEM, TEM, EDX, XRD, VSM and ICP-AES analysis. The Fe₃O₄@SiO₂@N-amidinoglycine@Pd⁰ proved to be a highly active catalyst for the Suzuki coupling reactions of various aryl halides with substituted phenylboronic acids in water, giving the desired products in excellent yields for short reaction times. Moreover, this catalyst can be easily recovered by using an external magnet and directly reused for several times without significant loss of activity.