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 site in copper-based catalysts can effectively tune the material performance for the 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 structural, compositional, and textural properties in the samples. Catalyst testing in the one-pot three-component reaction of organic halides, terminal alkynes, and sodium azide in water shows that the presence of an organic layer on the catalyst surface favours the reaction. Leaching experiments after eight successive cycles have been finally conducted to prove the stability of the materials reported herein.