Copper immobilized on biomimetic assembled calcium carbonate/carboxymethylcellulose hybrid: a highly active recoverable catalyst for CuAAC reactions

Abstract

A novel copper immobilized on biomimetic assembled carboxymethylcellulose/calcium carbonate hybrid (CuII@CMC/CaCO3) as an efficient heterogeneous catalyst for the synthesis of 1,2,3-triazoles has been described herein. The fabrication of CuII@CMC/CaCO3 is accomplished through a bioinspired mineralization process using sodium carboxymethylcellulose (CMC-Na) as the template and ion exchange agent, while the metathesis, nucleation, assemble, hybridization, and immobilization of Cu(II) occurred by successful treatment with CaCl2, Na2CO3, and CuSO4 in water at room temperature. The resultant CuII@CMC/CaCO3 hybrid was well characterized by various analyses such as FT-IR, XRD, SEM, EDX, EDX-mapping, TEM, and TGA techniques. In the presence of low copper loading of CuII@CMC/CaCO3 hybrid, benzylic halides, azide, and alkynes proceeded smoothly to afford 1,4-disubstituted 1,2,3-triazoles in high yields. The catalyst can be conveniently recovered from the reaction mixture by filter and reused for at least 5 consecutive runs with a slight drop in its catalytic activity. The remarkable activity and stability of the catalyst may be attributed to the coordination of both carboxyl and hydroxyl groups of the hybrid of CMC/CaCO3.