Hollow gold and platinum nanoparticles by a transmetallation reaction in an organic solution

Transmetallation reaction between hydrophobized silver nanoparticles with hydrophobized chloroaurate and chloroplatinate ions in chloroform results in the formation of hollow gold and platinum shell nanoparticles respectively

Synthesis of a stable gold hydrosol by the reduction of chloroaurate ions by the amino acid, aspartic acid

Development of reliable protocols for the synthesis of nanoparticles of well-defined sizes and good monodispersity is an important aspect of nanotechnology. In this paper, we present details of the synthesis of gold nanoparticles of good monodispersity by the reduction of aqueous chloroaurate ions by the amino acid, aspartic acid. The colloidal gold solution thus formed is extremely stable in time, indicating electrostatic stabilization via nanoparticle surface-bound amino acid molecules. This observation has been used to modulate the size of the gold nanoparticles in solution by varying the molar ratio of chloroaurate ions to aspartic acid in the reaction medium. Characterization of the aspartic acid-reduced gold nanoparticles was carried out by UV-visible spectroscopy, thermogravimetric analysis and transmission electron microscopy. The use of amino acids in the synthesis and stabilization of gold nanoparticle in water has important implications in the development of new protocols for generation of bioconjugate materials

One-step synthesis of hydrophobized gold nanoparticles of controllable size by the reduction of aqueous chloroaurate ions by hexadecylaniline at the liquid-liquid interface

Vigorous stirring of a biphasic mixture containing hexadecylaniline in chloroform and aqueous chloroauric acid results in the formation of gold nanoparticles of controllable size in the organic phase

A new method for the synthesis of hydrophobized, catalytically active Pt nanoparticles

A single step method for the synthesis of catalytically active, hydrophobic Pt nanoparticles by the spontaneous reduction of aqueous PtCl62− ions by hexadecylaniline molecules at a liquid-liquid interface is described

One-step synthesis of ordered two-dimensional assemblies of silver nanoparticles by the spontaneous reduction of silver ions by pentadecylphenol Langmuir monolayers

The single-step synthesis of silver nanoparticles by the reduction of silver ions present in the subphase under alkaline conditions by 3-pentadecylphenol (3-PDP) Langmuir monolayer and their assembly into ordered two-dimensional structures is described. The reduction of the silver ions occurs by electron transfer from ionized phenol groups of 3-PDP, which then stabilize the particles against aggregation. Similar reduction of aqueous silver ions was carried out at the interface with toluene bearing 3-PDP and yielded monodisperse silver nanoparticles that may be separated as a dry powder and redispersed in a range of organic solvents. The mechanism of reduction of silver ions by 3-PDP under alkaline conditions was studied by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, transmission electron microscopy (TEM), and chemical analysis by X-ray photoelectron spectroscopy (XPS), and is discussed in detail

Hydrophobic, organically dispersible gold nanoparticles of variable shape produced by the spontaneous reduction of aqueous chloroaurate ions by hexadecylaniline molecules

In addition to control over the size and monodispersity of nanoparticle, nanomaterial synthesis procedures are increasingly required to control their shape and assembly as well. We demonstrate in this paper synthesis of organically dispersible, hydrophobic gold nanoparticles of spherical shape and encased in triangular thin polyaniline shells by doing reaction under static conditions and assembly of these particles onto polymer nanorod/nanowire-like templates by varying the molar ratio of chloroaurate ions to hexadecylaniline and varying the solvent by the spontaneous reduction of aqueous chloroaurate ions by hexadecylaniline molecules in a biphasic reaction setup. Under stationary conditions (no stirring), a biphasic mixture of hexadecylaniline in toluene and chloroaurate ions in water leads to the electrostatic complexation of chloroaurate ions with hexadecylaniline at the liquid-liquid interface and their phase transfer into the organic phase, followed by their reduction by the hexadecylaniline molecules. By varying the conditions, the templating action of gold nanoparticles or the polyaniline nanodispersions can be tuned in the organic medium and resulting assembly

Langmuir-Blodgett films of laurylamine-modified hydrophobic gold nanoparticles organized at the air-water interface

The organization of hydrophobized colloidal gold nanoparticles at air-water interface and the formation thereafter of lamellar, multilayer films of the gold nanoparticles by the Langmuir-Blodgett technique is described in this paper. The hydrophobization of the colloidal particles was accomplished by the direct chemisorption of laurylamine molecules on aqueous colloidal gold nanoparticles during a phase-transfer process. While monolayers of the laurylamine-capped gold nanoparticles at the air-water interface were not amenable to layer-by-layer transfer onto solid supports, it was observed that addition of the water-insoluble amphiphile octadecanol to the gold nanoparticle solution improved the stability of the monolayer at the interface as well as the multilayer assembly protocol. The organization of the gold nanoparticles at the air-water interface was followed by surface pressure-area isotherm measurements while the formation of multilayer films of the nanoparticles by the Langmuir-Blodgett technique was monitored by quartz crystal microgravimetry, UV-vis spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy

Capping of gold nanoparticles by the amino acid lysine renders them water-dispersible

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