Copper nanoclusters

The microscopy results characterizing the Cu/ZnO catalyst are in accord with EXAFS data representing the dynamic morphology changes (39—41), and they also provide an important additional insight On the basis of the lattice-resolved images, the nature of the exposed facets of the projected copper nanoclusters and the epitaxial relationship between the copper and ZnO can be identified. The majority of the copper nanocrystals appear to be in contact with the ZnO support with their (111) facets, as was also observed for copper particles prepared by vapor... 

Novel copper nanoclusters were also synthesized using histidine as the surface ligand. As described for Cu°-(Cys), these clusters were highly air sensitive, therefore an anaerobic environment was necessary to prevent nanocluster degradation to copper oxides during characterization. UV studies revealed a plasmon resonance at 571 nm with TEM analysis confirming a size distribution of 6.9 2.4nm. ... 

An example of a polyamine dendrimer functionalised by 2-pyridylethyl- substituents is (167).269 The interaction of (167) with copper(II) acceptors gives metal derivatives containing one metal for each bis[2-(2-pyridyl)ethyl]amine moiety. (167) is found to bind approximately 32 Cu ions. Polyamidoamine species containing Cu ions can be reduced in solution to zerovalent copper nanoclusters, providing a metal nanocomposite.270 Such copper(O) solutions are stable for several months, owing to the surface properties of the host dendrimer molecules. 

First report on nanofabrication of metal nanoclusters, silver and copper nanoclusters. 

Electrochemical STM nanofabrication techniques usually involve either localized etching (dissolution), or plating (deposition) on the surface via a sharp STM tip. The first demonstration of nanostructuring was reported by Penner s group. They fabricated silver and copper nanoclusters of 20-50 nm wide and 1-7 nm high at predetennined position in the deposition process. In addition to metal clusters the deposition method was used to fabricate nano-sized polyaniline. The authors used a pulse voltage technique and fabricated polyaniline spots 10-60 run in diameter and 1-20 run in height. 

The Wacker reaction was chosen as a representative reaction since in this case the conversion of an alkene to a ketone or an aldehyde can be achieved in one step, which is of industrial relevance. The reaction was carried out in a biphasic water/ acetonitrile system at 50-60 °C in an oxygen atmosphere, using the copper/ polyaniline nanocomposite, as well as a bare copper nanocluster. In the system, copper is present in the zero-valent state supported by polyaniline. Although 2-decanone is the only product formed, the yield obtained is still relatively low. It has to be mentioned in this context that the reaction carried out in the presence of bare copper nanoclusters showed no evidence for the presence of 2-decanone, indicating that those copper nanoclusters alone do not bring about the oxidation of 1-decene. 

Copper nanoclusters are active in Sonogashira reactions involving aryl iodides and some bromides when TBAA is used as base [90],... 

The dendrimer-mediated synthesis of metal nanoparticles was initiated by the pioneering work of Tomalia [48] and Crooks [49] on synthesizing copper nanoclusters in 1998. In 1999, Crooks and Zhao reported two studies on the synthesis of Pt [50] and Pd [51] nanoparticles with PAMAM Starburst dendrimers. In these two studies, the synthesized Pt and Pd nanoparticles were used in electrocatalytic oxygen reduction and homogeneous hydrogenation reactions, respectively. 

Balogh L, Tomaha DA (1998) Poly(amidoamine) dendrimer-templated nanocomposites. 1. Synthesis of zerovalent copper nanoclusters. J Am Chem Soc 120 7355... 

He L, Liu H, Xiao C-X, Kou Y. Liquid-phase synthesis of methyl formate via heterogeneous carbonylation of methanol over a soluble copper nanocluster catalyst. Green Chem 2008 10 619-22. 

W.S. (2004) Three-dimensional self-assembled monolayer (3D SAM) of n-alkanethiols on copper nanoclusters. The Journal of Physical Chemistry B, 108, 11001-10. 

Stable nanometric copper clusters are efficient ligand-free catalysts, probably due to their great surface area [55]. In the reaction between benzyl azide and prop-2-yn-l-ol, copper nanocluster catalysis affords 100% conversion after 18 h [9]. 

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