Surface engineering of a Cu-based heterogeneous catalyst for efficient azide–alkyne click cycloaddition

In this work, we disclose that atomic-scale engineering of the active sites in copper-based catalysts can effectively tune the material performance for regioselective synthesis of triazoles, important building blocks for fine chemicals and pharmaceuticals. The copper catalysts have been prepared via impregnation of β zeolites with a Cu precursor, followed by post-synthetic modification with an organic ligand. The ligand is expected to partially cover the active sites, reducing the ensemble where the reaction takes place. The materials have been characterized by nitrogen adsorption, TEM, XRD, SEM-EDX, and FTIR spectroscopy to determine the structural, compositional, and textural properties of the samples. Catalyst testing in a one-pot three-component reaction of organic halides, terminal alkynes, and sodium azides in water shows that the presence of an organic layer on the catalyst surface favours the reaction. Leaching experiments in eight successive cycles have been conducted to prove the stability of the materials.