Highly Efficient and Reusable Microporous Schiff Base Network Polymer as a Heterogeneous Catalyst for CuAAC Click Reaction

A microporous Schiff base network (SNW) polymer containing melamine groups is synthesized as a specific metal template material and employed as a solid support to stabilize copper(I) ions. The Cu(I) ions are incorporated into the SNW structure through coordination with the nitrogen atoms present in the melamine groups. The Cu(I)-incorporated material shows a highly effective catalytic activity for the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Several azide and alkyne compounds are used to conduct the click reaction by using a little amount of catalyst and almost quantitative yields are attained. Leaching tests verify the heterogeneity of the catalyst and more importantly, the material shows reusability under the same experimental conditions without any substantial variation in its activity. All results display that the catalyst system is highly competent in view of preparation, stability, selectivity, recovery, and reusability for CuAAC reactions exhibiting potential use in the other copper-based organic reactions and polymerization processes. An efficient reusable microporous heterogeneous catalyst for copper(I)-catalyzed azide-alkyne cycloaddition reactions is reported. Copper(I) ions are coordinated to a nitrogen-rich polymeric network formed by Schiff base chemistry. The resulting copper-contained network catalyzes the click reaction in a ligand-free manner and is easily refined facilitating its reusability for further reactions, while preserving its activity after several cycles.