Copper Nanoclusters for Catalytic Carbon–Carbon and Carbon–Nitrogen Bond Formations

Abstract

Newly synthesized blue-emitting few-atom copper nanoclusters (CuNCs) have been successfully utilized for catalyzing C­(sp2)–C­(sp2) and C­(sp2)–N­(sp3) bond formations. Various substituted biphenyls and 2° aromatic amines have been synthesized in good yield using this copper catalyst at facile reaction conditions in dimethyl sulfoxide. The amount of required nanocatalysts is as low as merely 2 mol % for carrying out these reactions. These types of copper nanoclusters are promising as potential and cheap catalysts for replacing conventional metal nanoparticles and heavy-metal-ion-based organic catalysts. The optimized structure of Cu6(GS)2 [GS = C10H16N3O6S] from computational studies revealed the perfect arrangements of Cu atoms in CuNCs and their interactions with stabilizing ligands. It is evident from the structure that some free Cu sites are available in the nanocluster species. These kinds of coordinatively unsaturated sites are highly active toward the catalytic reactions. Matrix-assisted laser desorption ionization–time-of-flight (MALDI–TOF) analysis also supports the computational hypothesis. Interestingly, matrix-assisted laser desorption ionization–time-of-flight mass spectrometry (MALDI–TOF MS) and computational studies revealed the formation of several reaction key intermediates in catalyzing C­(sp2)–C­(sp2) bond formation.

Templated Synthesis of Copper Nanoclusters with a Hybrid Lysozyme-Polymer Material for Enhanced Fluorescence

“…Metal nanoclusters are atomically precise particles composed of ∼200 atoms or less and have emerged as an important class of material due to their diverse applications as catalysts, − fluorescent probes, − sensors, − and therapeutic agents, among others. ,− Because metal nanocluster properties are heavily dependent on their morphology, size, and surface chemistry, diverse and well-controlled synthetic methods are required for their production. ,, Copper nanoclusters (CuNCs) in particular have attracted significant attention compared to other noble metals (e.g. platinum, gold, silver) due to their low cost, , making them ideal for large-scale applications .…”

Multiple neighboring active sites of an atomically precise copper nanocluster catalyst for efficient bond-forming reactions

“…[29][30][31] Owing to their higher surface area, multiple active sites, and heterogenous nature, nanostructured materials (e.g., metal nanoparticles, MNPs) have shown great potential for catalytic performance as compared to traditional homogenous catalysts. [32][33][34][35][36][37][38] However, due to their ill-defined structure it is difficult to delineate the role of active sites in the reaction mechanism and, hence, a catalysis-by-design approach cannot be practically implemented in such systems. 39 On the other hand, atomically precise nanoclusters (NCs, o3 nm), featuring well-defined positions of metal and ligands while possessing diverse polyhedral structures, [39][40][41] could serve as an ideal catalytic platform to enable the bond-forming reactions with mechanistic understanding owing to their structurally defined multiple active sites and tolerability for recycling.…”

“…39,40,43,46 Due to their earth abundance, cost-effectiveness, and versatile ligand architecture, copper nanoclusters have recently emerged for sustainable catalysis of chemical reactions. 37,[47][48][49][50][51][52][53] The challenge in the development of new core-shell copper nanoclusters (CuNCs) that facilitate unique bond-forming reactions lies not only in their synthesis, but also in the unravelling of the reaction mechanism through atomically precise structure-property relationships of the CuNCs.…”

Planar Core and Macrocyclic Shell Stabilized Atomically Precise Copper Nanocluster Catalyst for Efficient Hydroboration of C–C Multiple Bond

“…The nanocluster family has grown in diversity, with most research focusing on coinage metals, i.e., gold, silver, and, more recently, copper. ,,− The inclusion of copper within the nanocluster family offers cost-reduction advantages and opens new opportunities for applications in sustainable synthesis and catalysis ,,− due to its easily accessible oxidation states and flexible ligand architectures. , However, developing new core–shell Cu NCs and understanding their catalytic bond-forming reactions remain in their infancy. To date, only a handful of high-nuclearity Cu NCs have been used as catalysts for a few sets of organic transformations such as click chemistry, hydrogenations of ketones, and photocatalytic C–C/C–N cross-couplings. , This may be attributed to the significant challenges associated with synthesizing large core–shell copper nanoclusters, including their flexible coordination modes, complex cuprophilic interactions, and susceptibility to aerial oxidation …”