Design and development of a copper–manganese oxide nanocatalyst for the sustainable synthesis of 1,4-disubstituted 1,2,3-triazoles†‡

Designing heterogeneous nanocatalysts comprising abundantly available transition metals for various organic transformations has captured significant interest in recent years owing to their convenient separation, reusability and low metal contamination after the reaction. Herein, we report the design and synthesis of CuO@MnO₂ nanocomposites using malachite, which is a renewable copper precursor with an E-factor of 1.64. The as-prepared CuO@MnO₂ nanocomposites were well characterized through field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM), powder X-ray diffraction (pXRD), energy-dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller techniques (BET). The catalytic efficiency of CuO@MnO₂ nanocomposites was explored for the synthesis of 1,4-disubstituted 1,2,3-triazoles from phenylacetylene, benzyl bromide and sodium azide under neat conditions. The sustainability of the present methodology was explored by evaluating green chemistry metrics such as the E-factor (0.84), reaction mass efficiency (54.45%), process mass intensity (1.84) and turnover number (901).