Nitrogen-Doped Mesoporous Carbon Loaded With Zn Single Atoms as a Catalyst for the Synthesis of 2,4(5)-Diarylimidazoles.

Single-atom catalysts have emerged as highly effective alternatives to conventional metal catalysts due to their uniform active sites and superior catalytic performance. Stabilizing single zinc atoms on nitrogen-doped mesoporous carbon (NMC) enhances their stability, selectivity, electrical conductivity, and compatibility with green chemistry principles. In this study, a Zn@NMC catalyst was synthesized via solvent evaporation-induced self-assembly, followed by thermal polymerization and pyrolysis, and characterized by 1H nuclear magnetic resonance (NMR), Brunauer-Emmett-Teller, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray mapping analyses. The catalyst was successfully applied in the one-pot Radziszewski synthesis of 12 2,4(5)-diarylimidazole derivatives from phenylglyoxal, various substituted benzaldehydes, and ammonium acetate. 1H NMR, 13C NMR, and Fourier transform infrared spectroscopy were used to characterize the products. Optimal results were obtained in methanol at room temperature (25 °C) for 12 h, affording the desired products in yields of up to 97%. The incorporation of isolated zinc atoms into the nitrogen-rich carbon matrix significantly improved selectivity toward the target diarylimidazoles by suppressing side reactions and preventing catalyst deactivation.