Mixed Valance Cu(I)/Cu(II)-MWCNT as Heterogeneous Catalyst for [Click-Carbene Insertion]-Cascade Reaction

Abstract

A novel heterogeneous nano-catalyst, Cu@Adenine-CO@MWCNT, has been designed and synthesized for the efficient construction of N-substituted 1,2,3-triazoles via [click–carbene insertion]-cascade reaction. The catalyst was prepared by immobilizing Cu(II) species onto adenine-functionalized multi-walled carbon nanotubes (MWCNTs), employing Cu(OAc)2 as the copper precursor. Notably, the reaction conditions promote partial in situ reduction of Cu(II) to Cu(I), leading to the formation of catalytically active mixed-valence Cu(I)/Cu(II) sites that enable efficient redox cycling throughout the cascade transformation. Comprehensive characterization of the nano-catalyst by FT-IR, P-XRD, FE-SEM, EDX, FE-TEM, XPS,BET, ICP-OES and TGA analyses confirmed its successful fabrication, structural integrity, and thermal stability. The developed catalyst exhibited high efficiency in promoting the synthesis of triazoles, affording the products in high yields, and demonstrated excellent recyclability over multiple reaction cycles with minimal loss of activity.