The in situ fabrication of ZIF-67 on titania-coated magnetic nanoparticles: a new platform for the immobilization of Pd(ii) with enhanced catalytic activity for organic transformations

Abstract

Considering the outstanding characteristics of metal organic frameworks (MOFs) and magnetic nanoparticles, herein we report a facile approach for the synthesis of a magnetic zeolitic-imidazolate-framework-supported palladium(II) catalyst. In brief, zeolitic imidazolate framework-67 (ZIF-67) was successfully incorporated onto the surface of titania-coated magnetic nanoparticles using ethane-1,2-diamine as a linker, and then Pd(II) was immobilized onto this. The resulting Pd@ZIF-67–Fe₃O₄–TiO₂ catalyst possesses a high surface area (205 m² g⁻¹), a large pore volume (0.10 cm³ g⁻¹), good magnetic responsivity (10.71 emu g⁻¹), and high stability. A comparative analysis of Pd@ZIF-67–Fe₃O₄–TiO₂ and Pd@Fe₃O₄–TiO₂ catalysts for the oxidation, reduction, and oxidative deprotection of oximes was done to investigate the effects of ZIF-67 on the catalytic performance of Pd species. Substantial differences in activity and stability were observed in the presence of ZIF-67, suggesting that ZIF-67 plays an important role in enhancing the activity of Pd(II). This superior catalytic activity and stability arises due to a synergistic effect between well-dispersed palladium species and highly porous ZIF-67, which was confirmed via XPS analysis. Moreover, the catalyst retains its structure, chemical environment, and good magnetic response even after five catalytic runs, as confirmed via FTIR, XRD, XPS, and VSM studies of reused catalyst samples.