Highly Efficient and Reusable Microporous Schiff Base Network Polymer as a Heterogeneous Catalyst for CuAAC Click Reaction

Abstract

A microporous Schiff base network (SNW) polymer containing melamine groups is synthesized as a specific metal template material and employed as a solid support to stabilize copper(I) ions. The Cu(I) ions are incorporated into the SNW structure through coordination with the nitrogen atoms present in the melamine groups. The Cu(I)‐incorporated material shows a highly effective catalytic activity for the copper(I)‐catalyzed azide–alkyne cycloaddition (CuAAC) reaction. Several azide and alkyne compounds are used to conduct the click reaction by using a little amount of catalyst and almost quantitative yields are attained. Leaching tests verify the heterogeneity of the catalyst and more importantly, the material shows reusability under the same experimental conditions without any substantial variation in its activity. All results display that the catalyst system is highly competent in view of preparation, stability, selectivity, recovery, and reusability for CuAAC reactions exhibiting potential use in the other copper‐based organic reactions and polymerization processes.

Metal-catalyzed azide-alkyne “click” reactions: Mechanistic overview and recent trends

“…A key advantage of this catalyst [35] compared to Sharpless catalyst is the tremendeous ligand acceleration of the reaction. Other recent well-defined supramolecular catalytic approaches for the CuAAC reactions such as polymer-supported catalysts of Cu(I)-poly(styrene-co-maleimide) (CuI-SMI) for the one-pot three-component click synthesis of 1,4-disubstituted-1H-1,2,3-triazoles [138], polymer-anchored PS-C22-CuI for three-component synthesis of 1,4-disubstituted 1,2,3-triazoles under aerobic conditions in water [173], polymersupported catalyst Amberlyst A-21-CuI for the synthesis of 1,4-disubstituted-1H-1,2,3-triazoles in CH 2 Cl 2 at r.t. [174], Cu(I)-incorporated microporous Schiff base network polymer for CuAAC in MeCN at r.t. [175], supramolecular material of polymer supported Cu(I) catalyst, (Cu(I)-poly(2-aminobenzoic acid), Cu(I)-pABA), showed excellent yield toward AAC reactions at r.t. in aqueous media [176]. The combined use of two polymer supported reagents (polystyrene-1,5,7-triazabicyclo[4,4,0]dec-5-ene/Cu and polystyrene-2-iodoxybenzamide) enabled the reliable CuAAC in the presence of an oxidant agent [177], CuI onto dimethylaminografted cross-linked polystyrene (CuI@A-21) for azide-alkyne click polymerization [178], and metal-organic framework (Cu-MOF, Cu(PTZ)(NSA) 0.5 ·H 2 O) for the solvent-free CuAAC [179], were also successfully achieved.…”

Melamine-based microporous polymer for highly efficient removal of copper(II) from aqueous solution

“…(a) CO 2 adsorption/desorption isotherms of SNW before and after treatment with Cu(II), and (b) the structure of Cu(II) coordinated SNW …”

“…SNW polymer was prepared according to the previously described procedure (elemental analysis for SNW: C 64.36%, N 27.22%, H 8.42%).…”

Photoinduced Cu(0)‐Mediated Atom Transfer Radical Polymerization

“…The second route is electron transfer between Cu(II) complexes and photochemically generated electron‐donor radicals from either additional photoinitiators, or directly from the alkyl halide, ligand, or via interaction of ligand with either monomer or with alkyl halides. The use of UV and visible light photoinitiators for the reduction of Cu(II) species in the ATRP and copper‐catalyzed azide–alkyne cycloaddition click chemistry processes has been investigated extensively. Recent studies from our laboratory presented that the spectral sensitivity of the photoinduced ATRP can be extended into the visible light region by using commercially available photoinitiators, dyes, dimanganese decacarbonyl, and semiconducting photocatalysts …”