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Membrane fouling, including organic, inorganic, and biological fouling, poses enormous challenges in membrane water treatment. Incorporation of copper-based nanomaterials in polymeric membranes is highly favored due to their exceptional antibacterial properties and capacity to improve membrane hydrophilicity. This review extensively explores the utilization of copper-based nanomaterials in membrane technology for water treatment, with a specific focus on enhancing anti-fouling performance. It elaborates on how copper-based nanomaterials improve the surface properties of membrane materials (such as porosity, hydrophilicity, surface charge, etc.) through physical and chemical processes. It summarizes the properties and potential antibacterial mechanisms of copper-based nanomaterials, primarily by disrupting microbial cell structures through the generation of reactive oxygen species (ROS). Furthermore, recent efforts to enhance the environmental sustainability, cost-effectiveness, and recyclability of copper-based nanomaterials are outlined. The attempts to offer insights for the advancement of anti-fouling practices in water treatment through the use of copper-modified polymer membranes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

A Cu-catalyzed three-component reaction of alkyne, azides (sulfonyl or phosphoryl azides), and N,N-dialkyloxyformamide dialkyl acetal via electrophilic addition of immonium ion to copper ketenimine is reported. This new protocol for the preparation of α,β-unsaturated amidine derivatives appears to offer high yield, mild conditions, and wide substrate scope. The reaction might involve the processes of copper ketenimine intermediate formation, electrophilic addition, and isomerization.

CuI-catalyzed aerobic oxidative synthesis of imidazoheterocycles has been achieved. Four hydrogen atoms were removed in one step. This protocol was compatible with a broad range of functional groups, and it has been also successfully extended to unsaturated ketones, bringing about the formation of alkenyl-substituted imidazoheterocycles, which were difficult to prepare by previous means. Preliminary mechanistic studies indicated that this reaction was most likely to proceed through a catalytic Ortoleva-King reaction. By using this method, the marketed drug Zolimidine could be prepared with 90% yield on a gram scale from commercially available materials.

A highly efficient protocol of copper catalysis for the one-pot synthesis of fused dibenzo[b,f][1,4]oxazepines is reported. The transformation involves a Smiles rearrangement, leading to the completely different regioselectivity from the classical cross-coupling. The easy reaction of aryl chlorides as substrates enhances the practical application of the methodology.

An efficient synthesis of indolo[1,2-c]quinazoline derivatives has been developed by copper-catalyzed sequential Ullmann N-arylation and aerobic oxidative C-H amination. The protocol uses readily available 2-(2-halophenyl)-1H-indoles and (aryl)methanamines as the starting materials to afford indolo[1,2-c]quinazolines, which are the core units of hinckdentine A.

A novel copper-catalyzed annulation of 2-alkylazaarenes with α,β-unsaturated carboxylic acids has been accomplished. This reaction featuring C-H olefination and decarboxylative amination processes provides a concise access to C-2 arylated indolizines from simple and readily available starting materials.

The cross coupling of the C-OMe bond adjacent to a nitrogen atom in dialkoxy-N,N-dialkylmethanamines with terminal alkynes was efficiently approached in the presence of copper catalyst under mild conditions to give 3-amino-1,4-diynes in good yields. The reaction is promoted by phosphine ligands and the chemistry provides a simple and efficient route to 3-amino-1,4-diynes. Importantly, the Michael addition occurred with as-prepared 3-amino-1,4-diynes to give the useful Michael-adducts containing tert-alkylamines in a very convenient way. Further studies revealed that (E)-1,5-diarylpent-1-en-4-yn-3-one was formed through the rearrangement by using the neutral alumina column, and the corresponding imine 2-(1,5-diphenylpent-2-en-4-ynylideneamino)ethanol was obtained in the presence of AgOTf.

A highly efficient protocol for the synthesis of pyrrolidones by the copper-catalyzed alkynylation/annulation of aliphatic amides with alkynyl carboxylic acids is discussed in this paper. A broad range of easily accessible alkynyl carboxylic acids were introduced at the β-methyl group of aliphatic amides with the assistance of an 8-aminoquinolyl auxiliary group via decarboxylation to achieve the subsequent cyclic CN bond formation within one hour. High selectivity of β-methyl groups over methylene groups was observed, and the extension of this catalytic system to the activation of methylene CH bonds failed. The substrates with two different groups at the α-position of the aliphatic amides lead to the formation of diastereoisomers which is determined by 1H NMR spectroscopy. The initially produced products with Z-configurations can be easily transformed to the corresponding products with E-configurations by the treatment with dilute p-toluenesulfonic acid after the reaction. This catalytic tandem decarboxylative cyclization provides a new opportunity for the direct functionalization of sp3 CH bonds. [ABSTRACT FROM AUTHOR]

An effective copper-mediated synthesis of 1,5-dialkyl-4-aryl-1,2,3-triazoles and 1,4-dialkyl-5-aryl-1,2,3-triazoles has been achieved by the use of different N-tosylhydrazones and alkyl amines. The scope of the substrates could be extended from anilines to aliphatic amines when 30 mol % amino acid is added into the reaction mixture. This methodology exhibits many notable features, such as broad substrates scope, high efficiency, and good regioselectivity. Preliminary mechanistic studies indicated that the reaction probably proceeded through a 1-tosyl-2-vinyldiazene intermediate and subsequent aza-Michael addition and NN bond formation process. [ABSTRACT FROM AUTHOR]

NNNifty targets: In a straightforward copper‐mediated synthesis of 1,4‐disubstituted and 1,4,5‐trisubstituted 1,2,3‐triazoles, readily available aniline and N‐tosylhydrazone substrates underwent cyclization through CN and NN bond formation (see scheme; Piv=pivaloyl, Ts=p‐toluenesulfonyl). This method enables the preparation of 1,2,3‐triazoles with high efficiency under mild conditions without the use of azides. [ABSTRACT FROM AUTHOR]

A series of unusual six-ring-fused heterocycles containing indole and quinoline skeletons was successfully synthesized by a copper-catalyzed reaction from 2-arylated indoles. Two new bonds were regioselectively formed from CH and CH coupling. 18O-Labelled experiments revealed that the dioxygen is not only the oxidant but also the reactant. [ABSTRACT FROM AUTHOR]

The cover picture, provided by Yuhong Zhang and co ‐ workers, illustrates a highly efficient synthesis of pyrrolidones by the copper ‐ catalyzed alkynylation/annulation of aliphatic amides with alkynyl carboxylic acids. A broad range of easily accessible alkynyl carboxylic acids was introduced at the β ‐ methyl group of aliphatic amides with the assistance of an 8 ‐ aminoquinolyl auxiliary group via decarboxylation to achieve the subsequent cyclic CN bond formation within one hour. This catalytic tandem decarboxylative cyclization provides a new opportunity for the direct functionalization of sp3 CH bonds. Details can be found in the full paper on pages 792 – 807 (J. Zhang, D. Li, H. Chen, B. Wang, Z. Liu, Y. Zhang, Adv. Synth. Catal.­ 2016, 358, 792 – 807; DOI: 10.1002/adsc.201500727). [ABSTRACT FROM AUTHOR]

A novel copper-mediated annulation of alkyl ketones with α,β-unsaturated carboxylic acids has been accomplished. This reaction provides a facile and regio-defined method for the synthesis of 2,3,5-trisubstituted furans from simple chemical reagents. [ABSTRACT FROM AUTHOR]

Depending on the metal complexes employed, regiodivergent C–H direct chlorination on 8-acylaminoquinolines could be realized. While the stoichiometric CuCl 2 /base persistently gave the C5-monochlorination, the Pd(II)-catalyzed chlorination by using N -chlorosuccinimide (NCS) as a chlorine source led to variable results mainly relying on the substitution pattern of the 8-acylaminoquinolines and the loading of NCS. This work demonstrated not only an unprecedented access to divergently halogenated quinolines, but also a less studied C(sp 2 )–H functionalization mode, namely the single-electron transfer (SET) mediated C(sp 2 )–H functionalization. [ABSTRACT FROM AUTHOR]

A novel copper-mediated annulation via an oxidative free-radical process is presented. [ABSTRACT FROM AUTHOR]

The new approach involves a sequential oxidation and arylation/vinylation process with assistance of an 8-aminoquinolyl auxiliary. [ABSTRACT FROM AUTHOR]