Synthesis and Characterization of Sulfonate and Phosphonate Functionalized Monolayer Protected Gold Clusters

Synthesis and Characterization of Sulfonate and Phosphonate Functionalized Monolayer Protected Gold Clusters
Author: Fiurasek Petr
Publisher:
Total Pages: 218
Release: 2003
Genre:
ISBN:

"Gold clusters protected with self-assembled monolayers of sodium, 10-mercaptodecanesulfonate, HS(CH2)10SO 3Na, and 11-mercaptoundecanylphosphonic acid, HS(CH2) 11PO3H2, were synthesized to provide negatively charged nanoparticles. The negatively charged end groups of the sulfonate- and phosphonate-monolayers protected clusters, SO3-MPCs and PO 3-MPCs, allowed the particles to be water soluble in addition to be stable in air, and can be dried and redissolved without change. Modifications of experimental conditions, namely the thiol:gold ratio, gold concentration and the type of surfactant, yielded MPCs of 1.8--5.7 nm core diameters with a broad range of size dispersity, and solubilities. Transmission electron microscopy, proton nuclear magnetic resonance (1H NMR), UV-Visible and infrared spectroscopies, thermogravimetric and zeta-potential analyses were consistent with nanoparticle formation. The chain conformation, dynamic behavior and ordering of SO3-MPCs and PO3-MPCs were further investigated by solid-state NMR. Despite the high surface curvature of the nanoparticles and the bulky end groups, medium length chains of SO 3-MPCs (C10) and PO3-MPCs (C11) showed a high degree of organization and restricted mobility when compare to long chains of alkanethiolate MPCs (C18). The more extensive hydrogen bonding interactions between the phosphonic acid groups led to a reduced chain mobility and a higher thermal stability. The PO3-MPCs exhibit a high order-disorder transition, partial decomposition and a very marked hysteresis in the chain recrystallization similar to MPCs stabilized by HS(CH2)nCO2H. Solid-state 31P-NMR allowed studies of the hydrogen-bonded self-assembled structure in the PO3-MPCs as well as in the bulk phosphonic acid. The 1.8 nm-diameter SO3-MPCs produced large aggregates in presence of poly(diallyldimethyl-ammonium chloride) (PDADMAC). However, the encapsulation of individual particles was favored when the same polyelectrolyte" --

Gold Clusters, Colloids and Nanoparticles I

Gold Clusters, Colloids and Nanoparticles I
Author: D. Michael P. Mingos
Publisher: Springer
Total Pages: 287
Release: 2014-09-27
Genre: Science
ISBN: 3319078488

The series Structure and Bonding publishes critical reviews on topics of research concerned with chemical structure and bonding. The scope of the series spans the entire Periodic Table and addresses structure and bonding issues associated with all of the elements. It also focuses attention on new and developing areas of modern structural and theoretical chemistry such as nanostructures, molecular electronics, designed molecular solids, surfaces, metal clusters and supramolecular structures. Physical and spectroscopic techniques used to determine, examine and model structures fall within the purview of Structure and Bonding to the extent that the focus is on the scientific results obtained and not on specialist information concerning the techniques themselves. Issues associated with the development of bonding models and generalizations that illuminate the reactivity pathways and rates of chemical processes are also relevant. The individual volumes in the series are thematic. The goal of each volume is to give the reader, whether at a university or in industry, a comprehensive overview of an area where new insights are emerging that are of interest to a larger scientific audience. Thus each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years should be presented using selected examples to illustrate the principles discussed. A description of the physical basis of the experimental techniques that have been used to provide the primary data may also be appropriate, if it has not been covered in detail elsewhere. The coverage need not be exhaustive in data, but should rather be conceptual, concentrating on the new principles being developed that will allow the reader, who is not a specialist in the area covered, to understand the data presented. Discussion of possible future research directions in the area is welcomed. Review articles for the individual volumes are invited by the volume editors. Readership: research scientists at universities or in industry, graduate students Special offer For all customers who have a standing order to the print version of Structure and Bonding, we offer free access to the electronic volumes of the Series published in the current year via SpringerLink.

Synthesis and Characterization of Monolayer Protected Gold Nanoparticles and a Gold-titanium Dioxide Nanocomposite Intended for Photocatalytic Degradation of Environmental Pollutants

Synthesis and Characterization of Monolayer Protected Gold Nanoparticles and a Gold-titanium Dioxide Nanocomposite Intended for Photocatalytic Degradation of Environmental Pollutants
Author: Piyadarsha Amartunga
Publisher:
Total Pages: 278
Release: 2010
Genre: Photocatalysis
ISBN:

Semiconductor and metal clusters in the nanometer size regime display interesting optical, electronic and chemical properties that are size dependant. Highly monodisperse gold nanoparticles of different sizes have been synthesized and isolated by newly developed methodologies, using tiopronin as the capping ligand. Titanium dioxide nanoparticles (TiO2) have been used as the photocatalytic center and gold nanoparticles have been attached on TiO2 to make a nanocomposite. According to the findings, gold nanoparticles play a vital role in enhancing the photocatalytic activity of TiO2, by facilitating the charge separation. Further, the photocatalytic activity also can be tuned by changing the gold loading on TiO2. The applicability of the nanocomposite has been evaluated towards the degradation of environmental pollutants.

Covalently Functionalized Gold Nanoparticles

Covalently Functionalized Gold Nanoparticles
Author: Michael Robert Ivanov
Publisher:
Total Pages: 177
Release: 2011
Genre: Capillary electrophoresis
ISBN:

The gold nanoparticle core composition, shape, size, self assembled monolayer (SAM) formation kinetics, and SAM ligand packing density are all evaluated for thioctic acid, 6-mercaptohexanoic acid, or 11-mercaptoundecanoic acid monolayers. Transmission electron microscopy (TEM), 1 H NMR, extinction spectroscopy, zeta potential, X-ray photoelectron spectroscopy (XPS), and flocculation studies are used to assess the morphology, surface chemistry, optical properties, surface charge, SAM packing density, and effective stability of carboxylated nanoparticles, respectively. Using these well-characterized nanostructures, applications of gold nanoparticle pseudostationary phases in capillary electrophoresis is studied.

Synthesis, Characterization and Assembly of the Binary Ligand Protected Gold Nanoparticles

Synthesis, Characterization and Assembly of the Binary Ligand Protected Gold Nanoparticles
Author: Hyewon Kim (Ph. D.)
Publisher:
Total Pages: 100
Release: 2013
Genre:
ISBN:

When a gold nanoparticle is coated with two dislike ligands, the ligands selfassemble on the nanoparticle surface and the phase separation occurs based on the miscibility and the size mismatch of two ligands, and the sizes of nanoparticles. When the size of the gold core is approximately between 3-8 nm, the stripe-like ordered domains of two ligands are formed. The stripe-like structure is not favored when you consider only the enthalpy. However, the long ligands obtain extra free-volumes when they are surrounded by the short ligands due to the curvature of a nanoparticle, hence, the entropy increases when two ligands are mixed on the nanoparticle surface. The balance between enthalpy and entropy leads to the state where the stripe-like arrangement of two ligands is thermodynamically the most stable. When the size of the gold core becomes smaller, the entropy contribution becomes less and less relevant, since the gain of free-volume when two different ligands are closely placed is smaller due to the larger curvature of smaller nanoparticles. Under this condition, the final morphology is primarily determined by the enthalpy of separation. Therefore, for small particles, two ligands phase separate into two bulk phases, resulting the Janus nanoparticles. In the first part of this thesis, we demonstrate that gold nanoparticles with a core diameter smaller than 1.5 nm form Janus nanoparticles in many ligand combinations. We used four different nanoparticles and different techniques to confirm the presence of a majority of Janus particles. All of them show similar cut-off sizes for the Janus-to-stripe transition. In the second part of this thesis, we show nanoparticle hydrogels using the selfassembly of the stripe nanoparticles. One of unique surface properties of the stripe nanoparticle is divalency. A particle coated with stripe-like domains implies two defect points at the poles of NPs. These two polar defects can be selectively functionalized with molecules that in turn can act as handles for further assemblies. The network structure is formed only using ionic interaction between NPs, and it requires both divalent anionic nanoparticles and divalent cations. Gels are investigated to determine their properties using rheological characterization.

Optical and Electrochemical Properties of Monolayer Protected Gold Clusters Modified with Fluorophores

Optical and Electrochemical Properties of Monolayer Protected Gold Clusters Modified with Fluorophores
Author: Mary Sajini Devadas
Publisher:
Total Pages: 254
Release: 2012
Genre:
ISBN:

Highly monodisperse Au clusters with different types of ligands were successfully synthesized with sizes varying from 1 nm to 13 nm. These preformed gold clusters were modified with fluorophores and pseudo-rotaxanes for developing better nonlinear optical materials for sensing and biological imaging purposes.