Cu(I)–Amidine Complex–Functionalized Lightly Cross-Linked Polyacrylamide: A Novel, Efficient Nano-Sized Heterogeneous Catalyst for Huisgen 1,3-Dipolar Cycloaddition (Click Reaction)

Abstract

A Cu(I)–amidine complex–functionalized lightly cross-linked polyacrylamide was successfully synthesized using Cu(I) iodide as copper source CPAM_Amd–CuI and comprehensively characterized using ICP, CHN, DR-UV/vis, FTIR, XRD, FE-SEM, EDAX, TG/DTG, TEM, and elemental analysis. As shown by TEM, Cu(I) particles are well dispersed and average 23.36 nm in diameter. An evaluation of the catalytic performance of CPAM_Amd–Cu(I) as a nano-sized heterogeneous catalyst was conducted in one-pot, three-component 1,3-dipolar cyclization (click) reactions. In the title reaction of sodium azide, alkyl halide, and a terminal alkyne in water, the polymeric Cu(I) catalyst displayed excellent activity and stability, yielding a high yield of up to 98% of 1,4-disubstituted 1,2,3-triazoles. Furthermore, the newly developed polymeric Cu(I) catalyst revealed excellent stability and recyclability in the heterogeneous title reactions over six cycles, losing only a minor amount of catalytic activity. Moreover, the designed support did not leach Cu(I) very readily.