Fabrication of novel and promising heterogeneous nanocatalyst Fe₂O₃-g-C₃N₄/Cu(II) derived from MIL-53(Fe) and decorated with copper as an efficient and reusable catalyst for Hantzsch reaction

Copper-containing Fe₂O₃ with g-C₃N₄ framework (Fe₂O₃-g-C₃N₄/Cu(II)) composite is fabricated and its characterization was followed by various analyses. Firstly, the compound MIL-53(Fe) was constructed and utilized as a precursor to generate Fe₂O₃. Fe₂O₃-g-C₃N₄ was prepared by pyrolysis of MIL-53(Fe) material in the presence of urea and KBr at 550 °C and then treated with Cu(NO₃)₂.3H₂O to produce Fe₂O₃-g-C₃N₄/Cu(II) composite. The constructed hybrid nanomaterial was applied as a nanocatalyst in the formation of polyhydroquinoline derivatives via Hantzsch reaction with excellent yields between 91 and 97% in the absence of solvent at 75 °C (10 mg catalyst loading within 20–35 min). Owing to the synergistic effect of basic sites (C₃N₄) and acidic sites (Cu), Fe₂O₃-g-C₃N₄/Cu(II) displayed exceptional catalytic activity. Moreover, Fe₂O₃-g-C₃N₄/Cu(II) has exhibited recyclability for six runs.