Zinc(II)‐poly(urea‐formaldehyde) supported on magnetic nanoparticles: A hybrid nanocatalyst for green synthesis of spiropyrans, spiroxanthenes, and spiropyrimidines
Mohammad Ali Bodaghifard, Zahra Mousavi
Abstract
Immobilization of metal ions onto inorganic supports has very interesting biological, industrial, and catalysis applications. In this study, CoFe 2 O 4 @SiO 2 @PUF@Zn(OAc) 2 nanostructure was successfully fabricated by immobilization of zinc acetate on the surface of poly(urea‐formaldehyde) supported on magnetic CoFe 2 O 4 @SiO 2 nanoparticles through a layer‐by‐layer assembly. The structure of hybrid nanoparticles was characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, energy‐dispersive X‐ray spectroscopy, inductively coupled plasma atomic emission spectroscopy, vibrating sample magnetometry, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy, and transmission electron microscopy. Zinc‐poly(urea‐formaldehyde) supported on magnetic nanoparticles (MNPs@SiO 2 @PUF@Zn) was successfully used for the synthesis of spirooxindolopyran and spirooxindoloxanthene derivatives in aqueous medium as an environmentally benign condition. High yields, short reaction times, green solvent, reusability without significant reduction in catalytic activity, and simple separation of the catalyst using an external magnet along with environmental compatibility are some benefits of this procedure.