Structural and Dynamic Properties of Water near Monolayer-Protected Gold Clusters with Various Alkanethiol Tail Groups

Yang, An-Cheng; Weng, Cheng‐I

doi:10.1021/jp910101t

Cited by 43 publications

(67 citation statements)

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“…This indicates the biased orientation of water molecules towards hydrophilic terminal groups and their hydrogen bond interactions with them. Similar results have been reported from the simulation studies in earlier studies [43,44]. Thus both the hydrophobic and hydrophilic gold SAM surfaces have induced a large reorientation of water molecules at the interface.…”

Section: Hydrationsupporting

confidence: 89%

A simulation study on the thermal and wetting behavior of alkane thiol SAM on gold (111) surface

Devi

2014

Progress in Natural Science: Materials International

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Molecular dynamics simulations have been performed to investigate the structural, thermal and wetting properties of self-assembled monolayer (SAM) of alkane thiol on gold surface. The specific heat capacity of the gold SAM surface was found to linearly increase with the temperature in the range 100-300 K. It was found to drop down at 400 K and this decrease might be attributed to the disorder of the SAM chains. Hydration of gold SAM surface for two different terminal groups, namely methyl (hydrophobic), and hydroxy (hydrophilic) was studied at room temperature. The difference in their wetting behavior and the structure of their interfacial water were examined from the estimation of the z density profile, radial distribution function, hydrogen bonds and orientation of water dipoles in the interfacial region. The present simulation results suggest that the wetting behavior of the gold SAM surface can be modified by altering the terminal functional group of the SAM chains.

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Section: Hydrationsupporting

confidence: 89%

A simulation study on the thermal and wetting behavior of alkane thiol SAM on gold (111) surface

Devi

2014

Progress in Natural Science: Materials International

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“…This feature of the Au−S interface, which exists also for self-assembled monolayers on bulk Au, has not been incorporated previously for AuNP simulations with classical force fields. 28,29,31,41 with the water density at the given temperature. The overall number of atoms in the simulated systems was around 33 000.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment

et al. 2012

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Charged monolayer-protected gold nanoparticles (AuNPs) have been studied in aqueous solution by performing atomistic molecular dynamics simulations at physiological temperature (310 K). Particular attention has been paid to electrostatic properties that modulate the formation of a complex comprised of the nanoparticle together with surrounding ions and water. We focus on Au 144 nanoparticles that comprise a nearly spherical Au core (diameter ∼2 nm), a passivating Au−S interface, and functionalized alkanethiol chains. Cationic and anionic AuNPs have been modeled with amine and carboxyl terminal groups and Cl − /Na + counterions, respectively. The radial distribution functions show that the side chains and terminal groups show significant flexibility. The orientation of water is distinct in the first solvation shell, and AuNPs cause a long-range effect in the solvent structure. The radial electrostatic potential displays a minimum for AuNP − at 1.9 nm from the center of the nanoparticle, marking a preferable location for Na + , while the AuNP + potential (affecting the distribution of Cl − ) rises almost monotonically with a local maximum. Comparison to Debye−Huckel theory shows very good agreement for radial ion distribution, as expected, with a Debye screening length of about 0.2−0.3 nm. Considerations of zeta potential predict that both anionic and cationic AuNPs avoid coagulation. The results highlight the importance of long-range electrostatic interactions in determining nanoparticle properties in aqueous solutions. They suggest that electrostatics is one of the central factors in complexation of AuNPs with other nanomaterials and biological systems, and that effects of electrostatics as water-mediated interactions are relatively long-ranged, which likely plays a role in, e.g., the interplay between nanoparticles and lipid membranes that surround cells. ■ INTRODUCTIONNanoparticles (NPs, size range 1−100 nm) have many interesting properties, as they bridge the gap between bulk materials and atomic or molecular structures.1,2 Typically, the physical properties of bulk materials do not depend on the size of the sample, while at the nanoscale size-dependent properties are frequently encountered. Two contributing factors for the size dependence are (a) number of surface atoms whose percentage reduces as the NP size increases toward the bulk limit and (b) quantum confinement effects at the smallest length scales (<10 nm) where the electronic structure plays a significant role in determining the composition, stability, structure, and function of NPs. 3,4 Nanoparticles often display fascinating optical properties because of quantum effects, and, e.g., gold nanoparticles (AuNPs) appear from yellow to deep red and black in solution depending on their size. 5 In photovoltaic cells, absorption of solar radiation is much higher for semiconductor materials comprised of NPs than for continuous sheets of thin films (e.g., CdTe, ZnO).6 For phase-change materials used in optical data storage and nonvolatile computer ...

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“…Hence, it is important that the system behaves in a reasonably consistent manner irrespective of the degree of coarse-graining or the choice of the potential model used. There exist few studies in literature that have been performed on nanocrystal systems with explicit all atom models [16][17][18] and most studies have employed coarse-grained models. Thus, there is a lack of a "gold standard" from an explicit all atom simulation reference point to test the effectiveness of coarse-grained models.…”

Section: Intermolecular Potential Modelsmentioning

confidence: 99%

“…More recent work by Schapotschnikow and Vlugt, 11 also on sub-3-nm gold nanoparticles, was the first to include the effect of the role of the solvent to influence the adsorption of ligands during the assembly process, and the effect of the curvature of the gold surface on phase behavior. Lane et al 16 and Yang et al 17,18 have also studied solvent effects on alkane ligands attached to nanoparticles in different solvents, such as water and decane. We shall address solvent effects in a subsequent paper.…”

Section: Introductionmentioning

confidence: 99%

Explicit all-atom modeling of realistically sized ligand-capped nanocrystals

Kaushik

Clancy

2012

The Journal of Chemical Physics

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We present a study of an explicit all-atom representation of nanocrystals of experimentally relevant sizes (up to 6 nm), "capped" with alkyl chain ligands, in vacuum. We employ all-atom molecular dynamics simulation methods in concert with a well-tested intermolecular potential model, MM3 (molecular mechanics 3), for the studies presented here. These studies include determining the preferred conformation of an isolated single nanocrystal (NC), pairs of isolated NCs, and (presaging studies of superlattice arrays) unit cells of NC superlattices. We observe that very small NCs (3 nm) behave differently in a superlattice as compared to larger NCs (6 nm and above) due to the conformations adopted by the capping ligands on the NC surface. Short ligands adopt a uniform distribution of orientational preferences, including some that lie against the face of the nanocrystal. In contrast, longer ligands prefer to interdigitate. We also study the effect of changing ligand length and ligand coverage on the NCs on the preferred ligand configurations. Since explicit allatom modeling constrains the maximum system size that can be studied, we discuss issues related to coarse-graining the representation of the ligands, including a comparison of two commonly used coarse-grained models. We find that care has to be exercised in the choice of coarse-grained model. The data provided by these realistically sized ligand-capped NCs, determined using explicit all-atom models, should serve as a reference standard for future models of coarse-graining ligands using united atom models, especially for self-assembly processes.

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Structural and Dynamic Properties of Water near Monolayer-Protected Gold Clusters with Various Alkanethiol Tail Groups

Cited by 43 publications

References 50 publications

A simulation study on the thermal and wetting behavior of alkane thiol SAM on gold (111) surface

A simulation study on the thermal and wetting behavior of alkane thiol SAM on gold (111) surface

Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment

Explicit all-atom modeling of realistically sized ligand-capped nanocrystals

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Structural and Dynamic Properties of Water near Monolayer-Protected Gold Clusters with Various Alkanethiol Tail Groups

Cited by 43 publications

References 50 publications

A simulation study on the thermal and wetting behavior of alkane thiol SAM on gold (111) surface

A simulation study on the thermal and wetting behavior of alkane thiol SAM on gold (111) surface

Atomistic Simulations of Functional Au144(SR)60 Gold Nanoparticles in Aqueous Environment

Explicit all-atom modeling of realistically sized ligand-capped nanocrystals

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Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment