MnFe2O4@NH2@2AB-Ni: a novel, highly active, stable and magnetically recoverable nanocatalyst and use of this heterogeneous catalyst in green synthesis of spirooxindoles in water

In this research, superparamagnetic manganese ferrite nanoparticles were synthesized following a co-precipitation method, and subsequently coated with 3-aminopropyltriethoxysilane (APTES) through a silanization reaction. Manganese ferrite nanoparticles afforded bidentate ligands as a result of the reaction between isatoic anhydride and amino-functionalized MnFe2O4. The amino-functionalized nanoparticles were treated with nickel acetate, giving the immobilized nickel complex. Finally, catalytic properties of the prepared nanoparticles were examined by a green synthesis of spirooxindoles in water and they showed excellent catalytic activity. Recovery of the catalyst was simply achieved by applying an external permanent magnet. The isolated catalyst was reused for new reaction runs without significant loss of catalytic activity.