Immobilized Cu(II) Schiff-base complex supported on Fe3O4 magnetic nanoparticles: A highly efficient and reusable new catalyst for the synthesis of pyranopyridine derivatives

A new heterogeneous cupper (II) Schiff-base complex immobilized on silica-coated nanomagnetic Fe3O4 was synthesized from acetylacetonate (acac) and 2- aminothiophenol (ATP). The newly composed nanocatalyst Fe3O4@SiO2-acac-2ATPCu( II) was structurally characterized by several analytical techniques such as Fouriertransform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The catalytic activity of Fe3O4@SiO2-acac-2ATP-Cu(II) nanoparticles was investigated for the synthesis of pyrano[2,3-b]pyridine derivatives from one-pot three-component reaction of aldehydes, malononitrile, and 3-cyano-6-hydroxy-4-methyl-pyridin-2(1H)- one. A high catalytic performance was exhibited by this nanocatalyst under solventfree conditions and excellent yields of the products were achieved from this reaction in reasonably short reaction times. The nanoparticles can be easily separated from the reaction mixture simply by magnetic decantation and reused for several fresh consecutive runs without significant loss of catalytic activity