Copper(I)-Schiff Base Catalyzed Green Synthesis of Azides and Triazoles

Introduction: Developing efficient and environmentally friendly catalytic systems remains a key goal in modern synthetic chemistry. This study reports the synthesis and characterization of a copper(I) complex, [CuI(L4Br)I], incorporating the bidentate Schiff base ligand L4Br (N,N′-bis(4-bromobenzylidene)-2,2-dimethylpropane-1,3-diamine), and its evaluation as a catalyst in click-type transformations. Methods: The complex was prepared by reacting CuI with L4Br under mild conditions. Its structure was confirmed by elemental analysis, FT-IR spectroscopy, and 1H NMR spectroscopy. The redox behavior of Cu(II)/Cu(I) was studied using cyclic voltammetry in a pH 7.0 buffer. Catalytic activity was tested in the azidation of benzyl bromides and the one-pot synthesis of 1,2,3-triazoles via three-component reactions in water. Results: Spectroanalytical techniques confirmed the synthesis of the required products. Electrochemical study revealed a quasi-reversible Cu(II)/Cu(I) couple. The catalyst efficiently converted various benzyl bromides to benzyl azides and promoted the one-pot cycloaddition of phenylacetylene with sodium azide and benzyl bromides, affording 1,2,3-triazoles in excellent yields within short reaction times. Discussion: Catalytic performance arises from the redox flexibility and structural stability of the Cu(I) center, enabling effective substrate activation and product formation in aqueous medium. Conclusion: [CuI(L4Br)I] functions as an efficient, stable, and environmentally benign catalyst for click-type transformations, offering simplicity, high yields, and sustainable reaction conditions.