Efficient one-pot synthesis of 1,4-disubstituted-1,2,3-triazoles catalysed by NiO/Cu2O/CuO nanocomposites under microwave irradiation

The Cu-catalysed azide-alkyne cycloaddition (CuAAC) reaction, also known as the "click" reaction, is a powerful tool in organic synthesis due to its high efficiency, regioselectivity, and mild reaction conditions. However, the use of homogeneous copper catalysts often leads to challenges like separation and disposal, limiting their applicability in industrial settings. This study aimed to develop a novel heterogeneous catalyst utilizing NiO/Cu2O/CuO nanocomposites (NCs) for the selective and efficient synthesis of 1,4-disubstituted-1,2,3-triazoles via the click reaction. NiO/Cu2O/CuO NCs were prepared by a simple co-precipitation method. The catalytic activity of the prepared NCs was evaluated for the one-pot, three-component click reaction between benzyl bromide analogues, sodium azide, and phenyl acetylene under various conditions: ambient temperature, thermal heating, and microwave irradiation. The reaction progress was monitored by TLC, and the products were isolated and characterized by SEM, FTIR, XRD, and XPS. The NiO/Cu2O/CuO NCs exhibited superior catalytic performance compared to Cu2O/CuO nanoparticles (NPs). They facilitated the exclusive formation of the desired 1,4-isomer under all tested conditions. Notably, under microwave irradiation, the NiO/Cu2O/CuO NCs delivered significantly higher yields (89-96%) compared to Cu2O/CuO NPs (76-82%) for diverse triazole compounds. Characterization confirmed the successful synthesis of the NCs and the purity of the triazole products. Utilizing water as the solvent under microwave irradiation offered several advantages, including faster reaction rates, higher yields, efficient product isolation, and excellent recyclability of the catalyst. This study demonstrates the effectiveness of NiO/Cu2O/CuO NCs as a novel heterogeneous catalyst for the selective and efficient synthesis of 1,4-disubstituted-1,2,3-triazoles. The simple and efficient method, coupled with the advantages of water as a solvent and microwave-assisted heating, presents significant potential for various applications in organic synthesis and beyond.