Green and Sustainable Synthesis of Benzimidazoles Using a Novel Cu (II)-Schiff Base Complex Anchored to Silica-Coated Magnetite Nanoparticles

Abstract

A new nanocatalyst, MNPs@AA:Cu, has been developed by immobilizing a Cu (II)-aminoacetophenone-Schiff base complex onto the surface of silica-coated magnetite nanoparticles. The nanocatalyst was prepared using readily available reagents and thoroughly investigated using FT-IR, XRD, TGA, FE-SEM, EDS, VSM, and N₂ adsorption–desorption (BET) techniques. The results confirm that the MNPs@AA:Cu nanoparticles exhibit a uniform size distribution with minimal aggregation and demonstrate remarkable stability up to 250°C. Additionally, the integrity of the Fe₃O₄ core remains intact, and the surface coating shows no phase changes. The catalytic activity of a sustainable heterogeneous catalyst was evaluated in the synthesis of various biologically important benzimidazole derivatives from different benzaldehydes and o-phenylenediamine under conventional heating solvent-free conditions, resulting in good to excellent yields of the desired products. More importantly, the catalyst’s magnetic properties enable it to be easily recovered using an external magnet and reused six times without any significant decrease in its catalytic activity or leaching of copper.