Cu (II)-β-cyclodextrin complex stabilized on magnetic nanoparticles: A retrievable hybrid promoter for green synthesis of spiropyrans

The magnetic core of manganese ferrite (MnFe2O4) nanoparticles has a significant stability in comparison with ferrite (Fe3O4) nanoparticles. The unique supramolecular properties of beta-cyclodextrin (beta-CD), such as hydrophobic cavity, hydrophilic exterior and -OH functional groups, make it a good candidate for functionalization and catalytic application. So, a surface-modified magnetic solid support with the Cu (II)-beta-CD complex was prepared. The structure of nanoparticles was characterized by Fourier transform-infrared spectroscopy, X-ray powder diffraction, thermogravimetric analysis, vibrating-sample magnetometry, inductively coupled plasma-optical emission spectrometry and scanning electron microscope analyses. The catalytic activity of these nanoparticles was investigated in the synthesis of spiropyrans and high yields of desired products obtained under green media. Some advantages of this novel catalyst for this reaction are high yields, short reaction times, green solvent and conditions, easy workup procedure, negligible copper leaching, reusability without a significant diminish in catalytic efficiency, and simple separation of nanocatalyst by using an external magnet alongside the environmental compatibility and sustainability.