Self‐Assembled Monolayers on Gold Nanoparticles

Badia, Antonella; Singh, Shanti; Demers, Linette M.; Cuccia, Louis A.; Brown, G. R.; Lennox, R. Bruce

doi:10.1002/chem.19960020318

Cited by 312 publications

(412 citation statements)

References 16 publications

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“…First, most of the solid-state free energy is due to the enthalpic gain in the interdigitation of the ligand molecules, but in the nanoparticles chosen, because of the charges present in the NPs ligand shell, we can assume that the amount of interdigitation is negligible. We confirmed this using differential scanning calorimetry according to methods in the literature (23,29,30). More importantly, the same nanoparticles (powders from the same batch) were used to perform the solvation studies in all of the solvents presented in Fig.…”

Section: Discussionmentioning

confidence: 67%

The role of nanostructure in the wetting behavior of mixed-monolayer-protected metal nanoparticles

Centrone

Penzo

Sharma

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

108

103

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Self-assembled monolayer-protected nanoparticles are promising candidates for applications, such as sensing and drug delivery, in which the molecular ligands' interactions with the surrounding environment play a crucial role. We recently showed that, when gold nanoparticles are coated with a binary mixture of immiscible ligands, ordered ribbon-like domains of alternating composition spontaneously form and that their width is comparable with the size of a single solvent molecule. It is usually assumed that nanoparticles' solubility depends solely on the core size and on the molecular composition of the ligand shell. Here, we show that this is not always the case. We find that the ligand shell morphology affects the solubility of these nanoparticles almost as much as the molecular composition. A possible explanation is offered through a molecular dynamics analysis of the surface energy of monolayers differing only in their domain structure. We find that the surface free energy of such model systems can vary significantly as a function of ordering, even at fixed composition. This combined experimental and theoretical study provides a unique insight into wetting phenomena at the nano- and subnanometer scale.

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Section: Discussionmentioning

confidence: 67%

The role of nanostructure in the wetting behavior of mixed-monolayer-protected metal nanoparticles

Centrone

Penzo

Sharma

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

108

103

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“…[43][44][45][46] In a similar manner it is expected that only one set of resonances should be observed in the 1 H NMR spectrum of the DMAP stabilized palladium nanoparticle dispersion that can be attributed to DMAP physisorbed on the nanoparticles and free in solution. Griffin has previously observed the presence of additional resonances similar to those observed here in the 1 H NMR spectrum of a deliberately under-reduced preparation of DMAP stabilized gold nanoparticles.…”

Section: H Nmr Characterisation Of the Dmap Stabilized Palladium Nanomentioning

confidence: 74%

Preparation and Characterization of 4-Dimethylaminopyridine-Stabilized Palladium Nanoparticles

2007

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Abstract.DMAP stabilized palladium nanoparticles with a mean diameter of 3.4 0.5 nm are prepared from the aqueous phase reduction of Na 2 PdCl 4 using NaBH 4 in the presence of DMAP. TEM and UV-Vis spectroscopy characterization of the nanoparticle dispersion shows no obvious change in the nanoparticles several months after preparation.1 H NMR spectroscopy of the nanoparticles shows that the nanoparticle dispersion also contains a boron/DMAP complex and two palladium/DMAP complexes. One of the palladium complexes crystallizes out of the dispersion and is identified as Pd(DMAP) 4 (OH) 2 by X-Ray Crystallography. Following extensive analysis it is believed that the palladium/DMAP complexes are formed following the oxidation of the palladium nanoparticles. The prepared nanoparticle dispersion promotes selective hydrogen/deuterium (H/D) exchange on the carbon atoms to the endocyclic nitrogen atom on the DMAP stabilizing ligands through reaction with D 2 O. This activity is attributed to the presence of the nanoparticles rather than to the presence of the oxidized palladium/DMAP complexes.

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“…At high temperature, these defects progress toward the interior, and after the melting point, both the outer and interior chains appear the same. 31 This is clear from differential scanning calorimetry (DSC) 43 and variabletemperature IR and NMR 44 measurements.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Alkyl Chains in Monolayer-Protected Au and Ag Clusters and Silver Thiolates: A Comprehensive Quasielastic Neutron Scattering Investigation

et al. 2004

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Temperature-dependent dynamics of monolayer-protected Au and Ag nanoclusters and silver thiolates have been investigated with quasielastic neutron scattering. The simplest motion in these systems is the uniaxial rotation of the chain, which evolves slowly with temperature. While longer chain monolayers (above C 8 ) on Au clusters are rotationally frozen at room temperature, dynamic freedom exists in lower chain lengths. In the superlattice solids of Ag clusters, the dynamics evolve slowly, and at superlattice melting, all the chains are dynamic. The data are consistent with a structure in which the monolayers form bundles on the planes of metal clusters and such bundles interdigitate, forming the cluster assemblies. In thiolates, the dynamics is distinctly different in long-and short-chain systems. It arises abruptly at the melting temperature in C 12 but a bit sluggishly in C 18 , whereas in C 6 and C 8 , it evolves with temperature. The data are correlated with temperature-dependent infrared spectroscopy, which preserves some of the progression bands even after the bulk melting temperature, but loses them completely above 498 K, suggesting a possible partially ordered phase in this temperature window. Our studies have established the fact that (a) no rotational freedom exists in several of the alkyl chain monolayers on metal cluster solids at room temperature, (b) simple uniaxial rotation explains the dynamics of these systems, (c) the dynamics evolves slowly, and (d) such motions arise abruptly in long-chain layered thiolates which are similar to planar thiolates. We find that longer chains can possess conformational defects at higher temperatures, which slow the rotational dynamics.

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Self‐Assembled Monolayers on Gold Nanoparticles

Cited by 312 publications

References 16 publications

The role of nanostructure in the wetting behavior of mixed-monolayer-protected metal nanoparticles

The role of nanostructure in the wetting behavior of mixed-monolayer-protected metal nanoparticles

Preparation and Characterization of 4-Dimethylaminopyridine-Stabilized Palladium Nanoparticles

Dynamics of Alkyl Chains in Monolayer-Protected Au and Ag Clusters and Silver Thiolates: A Comprehensive Quasielastic Neutron Scattering Investigation

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