Hydrothermally Developed ZnC₂O₄.2H₂O Nanocrystals as Efficient Copper-free Catalyst for the Synthesis of 1,4-Disubstituted 1,2,3-Triazoles in Water

In this work, we report the synthesis of nanostructured ZnC2O4.2H(2)O with irregular sheet-like morphology using a simple hydrothermal procedure. The as-synthesized ZnC2O4.2H(2)O nanocrystal (ZnC2O4 NC) is very stable and therefore, explored for the first time as highly efficient recyclable catalyst for the azide-alkyne cycloaddition (AAC) reaction. Our catalytic protocol is highly efficient and amenable to a variety of aromatic/aliphatic azide and alkyne substrates under mild reaction condition to afford regioselective 1,4-disubstituted 1,2,3-triazoles with good to excellent yields. Also, for the one pot synthesis of desired products, the developed method is exceedingly sustainable where azides are formed in-situ from their respective precursors. Our catalytic results outperformed most of the reported state-of-the-art works involving copper free nanoparticulate and zinc-based catalysts. All the original features of the recovered catalyst remained intact after 5(th) catalytic cycle which clearly suggests the efficiency of the Zn-based stable nanostructured material as alternative copper free catalysts for AAC reactions. The developed methodology could be extended for gram-scale synthesis of 1,2,3-triazoles.