Core-shell magnetic microspheres as heterogeneous catalyst for synthesis of benzimidazole

Abstract

γ-Fe2O3 was used to prepare γ-Fe2O3@SiO2, γ-Fe2O3@SiO2-NH2 and γ-Fe2O3@SiO2-NH2-COOH nanoparticles. Core-shell modification of IRMOF3 was used to obtain γ-Fe2O3@SiO2-NH2-COOH/IRMOF3 nanoparticles. γ-Fe2O3@SiO2-NH2-COOH/IRMOF3 nanoparticles were modified by activated arginine (Arg), glycine (Gly) and lysine (Lys) to synthesize γ-Fe2O3@SiO2-NH2-COOH/IRMOF3-Arg, γ-Fe2O3@SiO2-NH2-COOH/IRMOF3-Gly and γ-Fe2O3@SiO2-NH2-COOH/IRMOF3-Lys nanoparticles. The products were used as catalysts for condensation reactions of benzaldehyde and o-phenylenediamine. Infrared spectroscopy (IR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) spectra were used for the characterization. γ-Fe2O3@SiO2-NH2-COOH/IRMOF3-Gly nanoparticles showed outstanding catalytic effects as determined by a fluorescence spectrophotometer. In RP-HPLC spectra, the retention time of the reaction products was 2.458 min and 3.392 min. The results of the 1H NMR (400 MHz, MeOH-d 6) spectra showed γ-Fe2O3@SiO2-NH2-COOH/IRMOF3-Gly nanoparticles to be more active.