Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Chemistry and properties of nanocrystals of different shapes.

This tutorial review presents an introduction to the field of noble metal nanoparticles and their current applications. The origin of the surface plasmon resonance and synthesis procedures are described. A number of applications are presented that take advantage of the electromagnetic field enhancement of the radiative properties of noble metal nanoparticles resulting from the surface plasmon oscillations.

Why gold nanoparticles are more precious than pretty gold: noble metal surface plasmon resonance and its enhancement of the radiative and nonradiative properties of nanocrystals of different shapes.

Interest in catalysis by metal nanoparticles (NPs) is increasing dramatically, as reflected by the large number of publications in the last five years. This field, "semi-heterogeneous catalysis", is at the frontier between homogeneous and heterogeneous catalysis, and progress has been made in the efficiency and selectivity of reactions and recovery and recyclability of the catalytic materials. Usually NP catalysts are prepared from a metal salt, a reducing agent, and a stabilizer and are supported on an oxide, charcoal, or a zeolite. Besides the polymers and oxides that used to be employed as standard, innovative stabilizers, media, and supports have appeared, such as dendrimers, specific ligands, ionic liquids, surfactants, membranes, carbon nanotubes, and a variety of oxides. Ligand-free procedures have provided remarkable results with extremely low metal loading. The Review presents the recent developments and the use of NP catalysis in organic synthesis, for example, in hydrogenation and C--C coupling reactions, and the heterogeneous oxidation of CO on gold NPs.

Nanoparticles as Recyclable Catalysts: The Frontier between Homogeneous and Heterogeneous Catalysis

The development of novel materials is a fundamental focal point of chemical research; and this interest is mandated by advancements in all areas of industry and technology. A good example of the synergism between scientific discovery and technological development is the electronics industry, where discoveries of new semiconducting materials resulted in the evolution from vacuum tubes to diodes and transistors, and eventually to miniature chips. The progression of this technology led to the development * To whom correspondence should be addressed. B.L.C.: (504) 2801385 (phone); (504) 280-3185 (fax); bcushing@uno.edu (e-mail). C.J.O.: (504)280-6846(phone);(504)280-3185(fax);coconnor@uno.edu (e-mail). 3893 Chem. Rev. 2004, 104, 3893−3946

http://depa.fquim.unam.mx/amyd//archivero/FidelmarLechugaSanabria_4940.pdf

Recent advances in the liquid-phase syntheses of inorganic nanoparticles.

This Account reports the synthesis and characterization of dendrimer-encapsulated metal nanoparticles and their applications to catalysis. These materials are prepared by sequestering metal ions within dendrimers followed by chemical reduction to yield the corresponding zerovalent metal nanoparticle. The size of such particles depends on the number of metal ions initially loaded into the dendrimer. Intradendrimer hydrogenation and carbon−carbon coupling reactions in water, organic solvents, biphasic fluorous/organic solvents, and supercritical CO2 are also described.

http://rcrooks.cm.utexas.edu/research/resources/Publications/rmc113.pdf

Dendrimer-Encapsulated Metal Nanoparticles: Synthesis, Characterization, and Applications to Catalysis

: A new template synthesis strategy for preparing Cu nanoclusters within dendrimer 'nanoreactors' is demonstrated. Hydroxyl-terminated polyamidoamine (PAMAM) dendrimers of generation higher than 2 act as monodispersed templates as well as stabilizers for nanocluster synthesis. Cu(2+) ions are first quantitatively sorbed into the dendrimer via a strong coordinative interaction with interior amines and then chemically reduced to yield Cu nanoclusters. The nanoclusters are composed of a well-defined number of atoms. Importantly, cluster size can be controlled by varying the size of the host dendrimer nanoreactor (16-atom Cu cluster in G4 and 64-atom Cu cluster in G6 dendrimers). The clusters remain trapped within the dendrimers for extended periods of time, do not agglomerate, and do not precipitate. The clusters can also be oxidized to yield dendrimer-encapsulated Cu(2+).

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Preparation of Cu Nanoclusters within Dendrimer Templates

Extraordinarily stable, monodisperse noble metal nanoparticles can be prepared by using dendrimers as both templates and stabilizers. Dendrimer-encapsulated Pd nanoparticles (see the schematic representation) exhibit high catalytic activity for the hydrogenation of alkenes in water. The catalytic activity and selectivity of these materials can be controlled by adjusting the dendrimer generation.

Homogeneous Hydrogenation Catalysis with Monodisperse, Dendrimer-Encapsulated Pd and Pt Nanoparticles.

/pdf/dendrimer-encapsulated-pt-nanoparticles-synthesis-21ymuk28dl.pdf

Dendrimer‐Encapsulated Pt Nanoparticles: Synthesis, Characterization, and Applications to Catalysis

A microfluidic device having integrated components for conducting chemical operations. Depending upon the desired application, the components include electrodes for manipulating charged entities, heaters, electrochemical detectors, sensors for temperature, pH, fluid flow, and other useful components. The device may be fabricated from a plastic substrate such as, for example, a substantially saturated norbornene based polymer. The components are integrated into the device by adhering an electrically conductive film to the substrate. The film may be made of metal or an electrically conducting ink and is applied to the device through metal deposition, printing, or other methods for applying films. Methods for reducing bubble formation during electrokinetic separation and methods for heating material in a microfluidic device are also disclosed.

Mingqi Zhao

Papers

Dendrimer-Encapsulated Metal Nanoparticles: Synthesis, Characterization, and Applications to Catalysis

Preparation of Cu Nanoclusters within Dendrimer Templates

Homogeneous Hydrogenation Catalysis with Monodisperse, Dendrimer-Encapsulated Pd and Pt Nanoparticles.

Dendrimer‐Encapsulated Pt Nanoparticles: Synthesis, Characterization, and Applications to Catalysis

Microfluidic chip having integrated electrodes