Novel Schiff base Mn(III) and Co(II) complexes supported on Co nanoparticles: efficient and recyclable magnetic nanocatalysts for alcohol oxidation

摘要

In this study, efficient and highly selective heterogeneous catalysts were developed by immobilization of manganese and cobalt Schiff base complexes on Co magnetite nanoparticles (MNPs). Firstly, Co@SiO2 core-shell nanoparticles were synthesized through a one-pot reaction. Secondly, the Co@SiO2 was amino-functionalized using 3-aminopropyl triethoxysilane and then Schiff base ligand Co@SiO2[(EtO)(3)Si-L-2] was obtained by the reaction of the amino-functionalized nanoparticles with the dialdehyde of 1,2-bis(2-formyl naphthoxy methyl) benzene. Finally, Co@SiO2[(EtO)(3)Si-L-2]/M (M = Mn(III) and Co(II)) were successfully synthesized. These surface-modified nanoparticles were characterized using various techniques such as TEM, XRD, TGA, SEM, VSM, XPS, EDX and FT-IR. The catalytic activities of the prepared catalysts were investigated by employing them in the oxidation of various aromatic alcohols with an environmentally friendly oxidant under mild conditions. The catalysts can be readily recovered and reused in at least 5 consecutive cycles without significant leaching and loss their catalytic activity.