Green synthesis and characterization of NiFe2O4@ZnMn2O4 magnetic nanocomposites: An efficient and reusable spinel nanocatalyst for the synthesis of tetrahydropyrimidine and polyhydroquinoline derivatives under microwave irradiation

In this study, for the first time, NiFe 2 O 4 @ZnMn 2 O 4 magnetic nanocomposites (MNCs) were synthesized using a simple green sol–gel method. The synthesized nanocomposites comprehensive characterized using various analytical techniques including X‐ray Photoelectron Spectroscopy, powder X‐ray diffraction (XRD), transmission electron microscope, field emission scanning electron microscopy, energy dispersive X‐ray analysis, vibrating sample magnetometer, Brunauer Emmett Teller, and elemental mapping. XRD confirmed the spinel crystal structure of NiFe 2 O 4 @ZnMn 2 O 4 MNCs. ZnMn 2 O 4 has tetragonal spinel structure while NiFe 2 O 4 cubic. In microwave‐assisted tetrahydropyrimidine and polyhydroquinoline derivative production, NiFe 2 O 4 @ZnMn 2 O 4 MNCs showed good catalytic activity. An external magnet can remove catalyst from reactions, and their efficacy stays stable after four cycles.