Polyvinylpolypyrrolidone‐Stabilized Copper Nanoparticles as an Efficient and Recyclable Heterogeneous Catalyst for the Click of 1,2,3‐Triazoles in Water

Abstract

A simple, efficient, inexpensive, and friendly benign route for the preparation of highly stable monodisperse copper nanoparticles with an average of 4–5 nm is developed by using polyvinylpolypyrrolidone (PVPP) as a stabilizer. Chemical reaction of PVPP and copper(II) sulfate followed by the thermal chemical reduction of embedded copper(II) ions with ascorbic acid afford copper nanoparticles‐polyvinylpolypyrrolidone (CuNPs‐PVPP) nanocatalyst, which is systematically characterized by FT‐IR, Raman, transmission electron microscopy, X‐ray powder diffraction, scanning electron microscopy, dispersive X‐ray spectroscopy, and atomic absorption spectroscopy. The CuNPs‐PVPP system efficiently catalyzes the click chemistry reaction of azides–alkynes as well as one‐pot three‐component reactions to regioselectively produce the 1,4‐disubstituted‐1,2,3‐triazole isomer in excellent yields in water under mild reaction conditions. CuNPs‐PVPP is successfully recycled up to five times without significant loss of its catalytic efficiency and selectivity. Moreover, a mechanistic study is performed through density functional theory type calculations in order to explain the observed selectivity of CuNPs catalyst in copper(I)‐catalyzed azide–alkyne cycloaddition reactions. The cheap, simple work‐up, recoverability/reusability, and negligible residual traces in the final product (0.5 ppm) of this novel nanocatalyst are the significant features of this eco‐friendly green protocol.

N‐Heterocyclic Imine‐Supported Bimetallic Cu(II) Catalyst for Azide‐Alkyne Cycloaddition: Solvent‐free, Reductant‐free, ppm‐level Catalysis to Access 1,4‐Disubstituted Triazoles

“…All four Cu1-O acetate bond lengths lying between 1.9557( 17) Å and 1.9898( 16) Å, which are comparable and fall within the range of 1.9460(4) Å to 1.9983( 16) Å as described in the literature for analogous complexes. [26] Each perimidin-2-imine unit is axially coordinated to a copper atom through the nitrogen atom of imine moiety (C=NH) with a Cu-N (Cu1-N(3)) bond distance 2.2056( 17) Å, which is in good agreement with previously reported bond lengths of 2.1755 (19) Å. [27] The O1-Cu1-O2 bond angles and other O-Cu-O bond angles range from 88.69(9)°to 89.97(9)°, while O(1)-Cu(1)-N(3) and N(3)-Cu(1)-Cu1#1 bond angles are 100.02(7)°and 167.38(5)°, respectively.…”

“…The intricacy of mixing a biological system with organic components is a major limitation recognized by catalytic systems operating in an aqueous medium. [19] For this reason, it is of utmost significance to develop a straightforward and practical approach for the CuAAC reaction that does not need the use of any solvent and can be utilized even with a very low copper loading. [20] As a result, we made the strategic decision to investigate whether Cu(II) complexes with reductant-free could be used for the CuAAC reaction under neat conditions.…”

“…Despite the critical relevance of all aforementioned systems entailing low Cu loading, however, their widespread implementation is impeded by challenges such as complicated and lengthy synthetic processes, and the requirement of an inert reaction medium. The intricacy of mixing a biological system with organic components is a major limitation recognized by catalytic systems operating in an aqueous medium [19] . For this reason, it is of utmost significance to develop a straightforward and practical approach for the CuAAC reaction that does not need the use of any solvent and can be utilized even with a very low copper loading [20] .…”

Water-Soluble Nanocomposites Containing Co3O4 Nanoparticles Incorporated in Poly-1-vinyl-1,2,4-triazole

“…Magnetic nanocomposite polymeric materials are interesting for study from the point of view of applied and fundamental science [9]. Polymer matrices used as stabilizers improve the properties of nanocomposites: they make it possible to obtain particles with a higher degree of uniformity and a narrow range of particle size distribution, which makes them possible to use in medicine [10][11][12][13].…”

Copper(I)‐chitin biopolymer based: An efficient and recyclable catalyst for click azide–alkyne cycloaddition reactions in water

“…[5,6] A variety of homogeneous and heterogeneous catalytic systems for CuAAC reactions has been used for the click of 1,4-disubstitued-1,2,3-triazole derivatives. [7][8][9][10][11][12][13] In recent years, increasing efforts have been devoted to the use of eco-friendly polymer supports for the metal catalysts in view of obtaining heterogeneous catalysts that can be recovered and recycled. [14][15][16] In this context, naturally occurring polysaccharides such as cellulose, chitosan and alginate biopolymers have been employed as biosupports for the stabilisation of copper ions followed by their application for the regioselective synthesis of 1,4-disubstituted-1,2,3-triazoles under the click chemistry approach (Chart 1).…”