Fe3O4@SiO2nanoparticlesFacile synthesis of 1- and 5-substituted 1H-tetrazoles catalyzed byrecyclable ligand complex of copper(II) supported onsuperparamagnetic

tWe report a new method for preparing functionalized superparamagnetic Fe3O4@SiO2possessing highsaturation magnetization. Magnetite particles were prepared by simple co-precipitation method inaqueous medium, and then Fe3O4@SiO2nanosphere was synthesized by using nano Fe3O4as the core,TEOS as the silica source and polyethylene glycol (PEG 1000) as the surfactant. Then, the silica-coatedFe3O4nanoparticles were covered with ligand complex of Cu(II). The functionalized magnetic core–shellnanoparticles (MNPs) were investigated by Fourier transform infrared spectroscopy, transmission elec-tron microscopy, scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, dynamiclight scattering and N2adsorption/desorption. Also, its Cu content was determined by inductively cou-pled plasma (ICP) analyzer. Then, the immobilized copper complex was used as an efficient catalyst forsynthesis of 1- and 5-substituted 1H-tetrazoles from nitriles and amines in good to excellent yields. Theresults show that the supported catalyst could be conveniently recovered through the use of an externalmagnetic field and reused for subsequent reactions for at least 6 times with less deterioration in catalyticactivity.

1- and 5-substituted 1H-tetrazolesCore–shellSupported catalystMagnetic separationa