/pdf/self-assembled-monolayers-of-thiolates-on-metals-as-a-form-1neb0hj3k4.pdf

Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

1. Introduction 20642. Synthesis of Magnetic Nanoparticles 20662.1. Classical Synthesis by Coprecipitation 20662.2. Reactions in Constrained Environments 20682.3. Hydrothermal and High-TemperatureReactions20692.4. Sol-Gel Reactions 20702.5. Polyol Methods 20712.6. Flow Injection Syntheses 20712.7. Electrochemical Methods 20712.8. Aerosol/Vapor Methods 20712.9. Sonolysis 20723. Stabilization of Magnetic Particles 20723.1. Monomeric Stabilizers 20723.1.1. Carboxylates 20733.1.2. Phosphates 20733.2. Inorganic Materials 20733.2.1. Silica 20733.2.2. Gold 20743.3. Polymer Stabilizers 20743.3.1. Dextran 20743.3.2. Polyethylene Glycol (PEG) 20753.3.3. Polyvinyl Alcohol (PVA) 20753.3.4. Alginate 20753.3.5. Chitosan 20753.3.6. Other Polymers 20753.4. Other Strategies for Stabilization 20764. Methods of Vectorization of the Particles 20765. Structural and Physicochemical Characterization 20785.1. Size, Polydispersity, Shape, and SurfaceCharacterization20795.2. Structure of Ferro- or FerrimagneticNanoparticles20805.2.1. Ferro- and Ferrimagnetic Nanoparticles 20805.3. Use of Nanoparticles as Contrast Agents forMRI20825.3.1. High Anisotropy Model 20845.3.2. Small Crystal and Low Anisotropy EnergyLimit20855.3.3. Practical Interests of Magnetic NuclearRelaxation for the Characterization ofSuperparamagnetic Colloid20855.3.4. Relaxation of Agglomerated Systems 20856. Applications 20866.1. MRI: Cellular Labeling, Molecular Imaging(Inﬂammation, Apoptose, etc.)20866.2.

Magnetic Iron Oxide Nanoparticles: Synthesis, Stabilization, Vectorization, Physicochemical Characterizations, and Biological Applications

Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

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.

A simple one-step NaCl-assisted microwave-solvothermal method has been developed for the preparation of monodisperse α-Fe2O3 mesoporous microspheres. In this approach, Fe(NO3)3 · 9H2O is used as the iron source, and polyvinylpyrrolidone (PVP) acts as a surfactant in the presence of NaCl in mixed solvents of H2O and ethanol. Under the present experimental conditions, monodisperse α-Fe2O3 mesoporous microspheres can form via oriented attachment of α-Fe2O3 nanocrystals. One of the advantages of this method is that the size of α-Fe2O3 mesoporous microspheres can be adjusted in the range from ca. 170 to ca. 260 nm by changing the experimental parameters. High photocatalytic activities in the degradation of salicylic acid are observed for α-Fe2O3 mesoporous microspheres with different specific surface areas.

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Monodisperse α-Fe2O3 Mesoporous Microspheres: One-Step NaCl-Assisted Microwave-Solvothermal Preparation, Size Control and Photocatalytic Property

Layered hydroxide metal acetates (metal = zinc, cobalt, and nickel) have been prepared by a new route belonging to the chimie douce method. This novel method involves the hydrolysis, in polyol medium, of in situ-formed complexes supposed to be alkoxyacetates. These layered hydroxide metal acetates present poorly ordered character, and their X-ray patterns have features typical of lamellar compounds with turbostratic disorder. Their chemical formula was established to be M(OH)2-x(CH3COO)x·nH2O with (x, n) = (0.42, 0.31), (0.38, 0.53), and (0.40, 0.63) for Zn, Co, and Ni, respectively. The layered hydroxide nickel acetate has a classical brucite structure with a random substitution of some hydroxyl groups by acetate groups. The layered hydroxide zinc and cobalt acetates are isomorphous with the hydrozincite structure, in which cations are located in both octahedral and tetrahedral sites. The acetate anion behaves as a unidentate ligand in LHS−Ni and LHS−Co, where LHS indicates layered hydroxide salt, and is...

Layered Hydroxide Metal Acetates (Metal = Zinc, Cobalt, and Nickel): Elaboration via Hydrolysis in Polyol Medium and Comparative Study

Ruthenium nanoparticles were prepared by reduction of RuCl3 in a liquid polyol. The mean particle size was restricted to the 1−6 nm range by appropriate choice of the reduction temperature and the acetate ion concentration in the solution. Very narrow particle diameter distributions were obtained. In some samples, among nearly isotropic particles, platelets with aspect ratios as low as 1/4 were detected. Colloidal solutions in toluene were obtained by coating the metal particles with dodecane thiol. Self-assemblies of 4-nm-sized coated particles were studied on a transmission electron microscope grid. The dodecane thiol concentration in the colloidal solution was found to determine, within the particle monolayer, the formation of either columnar units made up of edgewise stacked platelets, or a hexagonal network with a mean distance between the particles of 2 nm. The stacking of hexagonal arrays of particles was also studied, and both closed-packed and noncompact stackings were found. In the noncompact st...

Ruthenium Nanoparticles: Size, Shape, and Self-Assemblies

A new route for the preparation of powdery metal, oxide and hydroxide materials is presented as a chimie douce alternative to the sol-gel method. It consists in the reduction or the hydrolysis of a metal salt dissolved and heated in a polyol medium. It appears through zinc and cobalt examples that the use of acetate precursors contrarily to chloride or sulfate ones leads to the precipitation of a solid (metal, oxide, hydroxide) whose nature depends on two main factors: the hydrolysis ratio, defined by the water to metal molar ratio, and the reaction temperature. As in the sol-gel method, acetate leads to the formation of intermediate alkoxyacetate complex. The absence of water favors metal formation while its presence favors oxide or hydroxyacetate formation.

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Synthesis of inorganic compounds (metal, oxide and hydroxide) in polyol medium: A versatile route related to the sol-gel process

Metastable solid solutions in the system ZnOCoO: synthesis by hydrolysis in polyol medium and study of the morphological characteristics

The title compound crystallizes in the monoclinic system with the space group P2 1 /n (No. 14). Crystal data: a = 9.794(3) A, b = 8.765(2) A, c = 15.280(3) A, β = 98.38(2)°, V = 1298(4) A 3 , Z = 4, d calc = 1.89 g cm -3 . The structure was solved from 1689 reflections with (F o ) 2 > 2σ(F o ) 2 . The refinement converged to final indexes R and R w , respectively equal to 0.0289 and 0.0309. The compound has a layered structure. The asymmetric unit contains a binuclear complex built up from two zinc atoms linked together through one acetate and one ethane-1,2-olato(-1) ions. The bidimensional character results from the linking of the dimeric complexes through acetate groups. Each complex is bonded to four other ones in a plane parallel to (001). Cohesion between nets is week since it is allowed by van der Waals forces only.

L. Poul

Papers

Layered Hydroxide Metal Acetates (Metal = Zinc, Cobalt, and Nickel): Elaboration via Hydrolysis in Polyol Medium and Comparative Study

Ruthenium Nanoparticles: Size, Shape, and Self-Assemblies

Synthesis of inorganic compounds (metal, oxide and hydroxide) in polyol medium: A versatile route related to the sol-gel process

Metastable solid solutions in the system ZnOCoO: synthesis by hydrolysis in polyol medium and study of the morphological characteristics

A new two-dimensional alkoxyacetate of zinc : structure of μ-acetato-μ-[ethane -1.2-olato(-1)]-diacetatodizinc