Copper Nanoparticles (copper + nanoparticle)

Distribution by Scientific Domains


Selected Abstracts


Unsupported Copper Nanoparticles in the 1,3-Dipolar Cycloaddition of Terminal Alkynes and Azides,

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2010
Francisco Alonso
Abstract Readily prepared copper nanoparticles were found to catalyse the 1,3-dipolar cycloaddition of azides and alkynes up to rates comparable to those of microwave chemistry. Both the preparation of the nanoparticles and the click reaction are carried out under mild conditions, in short reaction times and in the absence of any stabilising additive or ligand. A variety of 1,2,3-triazoles were prepared in excellent yields. A reaction mechanism was postulated on the basis of different reactivity studies and deuteration experiments. Copper(I) acetylides were demonstrated to be the real intermediate species. [source]


Three-Dimensional Fabrication by Reaction-Diffusion: "Remote" Fabrication via Three-Dimensional Reaction-Diffusion: Making Complex Core-and-Shell Particles and Assembling Them into Open-Lattice Crystals (Adv. Mater.

ADVANCED MATERIALS, Issue 19 2009
19/2009)
Reaction-diffusion processes initiated from the surfaces of small gel or polymer particles can fabricate complex three-dimensional structures inside these particles. Bartosz Grzybowski and co-workers show on page 1911 that the core/shell particles thus prepared can be further modified "remotely" by electrochemical exchange reactions. The image shows four cubical particles, each having a spherical core fabricated by reaction-diffusion and comprising copper nanoparticles. [source]


Synthesis of 2,5-Diaminoquinones by One-Pot Copper-Catalyzed Aerobic Oxidation of Hydroquinones and Addition Reaction of Amines

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009
Sungjin Kim
Abstract The aerobic oxidation of various hydroquinones was achieved by using copper nanoparticles entrapped in aluminum oxyhydroxide [Cu/AlO(OH)] at room temperature. Furthermore, 2,5-diamino-1,4-benzoquinones were synthesized directly from hydroquinone and amines by a one-pot procedure consisting of the copper-catalyzed aerobic oxidation of hydroquinones and the double addition of amines to the resulting quinones. [source]


Vesicles as reactors of nanoparticles: an anomalous small-angle X-ray scattering study of the domains rich in copper ions

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007
Attila Bóta
The formation of copper hydroxide and copper oxide particles in the gaps among the stacks of multilamellar vesicles is described, illustrating a new pathway in the preparation of nanometre-scale particles. The in situ structural characterization of both the solid particles and the vesicles as a reaction medium was performed in the initial and final states of the process by using anomalous small-angle X-ray scattering (ASAXS) and freeze-fracture methods. The ASAXS method provides a description of the particle-size distribution of the copper nanoparticles, in spite of the fact that they are present in low concentration. This method allows the particle formation and growth to be monitored throughout the whole time range of the synthesis. [source]


Toward Tailor-Made Biocide Materials Based on Poly(propylene)/Copper Nanoparticles

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 6 2010
Humberto Palza
Abstract A set of poly(propylene) composites containing different amounts of copper nanoparticles (CNP) were prepared by the melt mixed method and their antimicrobial behavior was quantitatively studied. The time needed to reduce the bacteria to 50% dropped to half with only 1,v/v % of CNP, compared to the polymer without CNP. After 4,h, this composite killed more than 99.9% of the bacteria. The biocide kinetics can be controlled by the nanofiller content; composites with CNP concentrations higher than 10,v/v % eliminated 99% of the bacteria in less than 2,h. X-ray photoelectron spectroscopy did not detect CNP at the surface, therefore the biocide behavior was attributed to copper in the bulk of the composite. [source]


Loss characteristics of coplanar waveguide transmission lines fabricated with copper nanoparticles

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2010
Hee-Jo Lee
Abstract This article investigates the high frequency characteristics of coplanar waveguide (CPW) lines fabricated with inkjet-printing technology on BT substrates. The optimal metallic thickness of a printed CPW line is approximately estimated to be 3 ,m. When printed lines with higher electrical conductivity are realized through additional surface preparation steps, the findings of this study suggest that the RF performance level of these printed lines will be comparable to that of the copper clad laminate lines in the microwave frequency region. Finally, aspects of such improvements as well as applications of these types of printed lines are discussed. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 780,782, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24987 [source]


Controlled Synthesis of Water-Dispersible Faceted Crystalline Copper Nanoparticles and Their Catalytic Properties

CHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2010
Dr. Yanfei Wang
Abstract We report a solution-phase synthetic route to copper nanoparticles with controllable size and shape. The synthesis of the nanoparticles is achieved by the reduction of copper(II) salt in aqueous solution with hydrazine under air atmosphere in the presence of poly(acrylic acid) (PAA) as capping agent. The results suggest that the pH plays a key role for the formation of pure copper nanoparticles, whereas the concentration of PAA is important for controlling the size and geometric shape of the nanoparticles. The average size of the copper nanoparticles can be varied from 30 to 80,nm, depending on the concentration of PAA. With a moderate amount of PAA, faceted crystalline copper nanoparticles are obtained. The as-synthesized copper nanoparticles appear red in color and are stable for weeks, as confirmed by UV/Vis and X-ray photoemission (XPS) spectroscopy. The faceted crystalline copper nanoparticles serve as an effective catalyst for N-arylation of heterocycles, such as the CN coupling reaction between p -nitrobenzyl chloride and morpholine producing 4-(4-nitrophenyl)morpholine in an excellent yield under mild reaction conditions. Furthermore, the nanoparticles are proven to be versatile as they also effectively catalyze the three-component, one-pot Mannich reaction between p -substituted benzaldehyde, aniline, and acetophenone affording a 100,% conversion of the limiting reactant (aniline). [source]