Behavior of water molecules near monolayer-protected clusters with different terminal segments of ligand

Yang, An Cheng; Weng, Cheng‐I; Chen, Tei Chen

doi:10.1063/1.3602721

Cited by 16 publications

(19 citation statements)

References 29 publications

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“…In recent years, there have been a few simulation studies on the interfacial properties of water molecules around the MPANs with different SAMs. [27][28][29][30][31][32] For example, earlier MD simulations proposed by Tay and Bresme 27,28 have been used to investigate the HBs, structure, and orientational ordering of water molecules around the MPAN with different alkylthiol SAMs. They found that the hydrophobic alkylthiols lead to about 2 to 3 HBs per interfacial water molecule so that the existence of dangling OH bonds can be observed at the nanoparticle surface.…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, the strong orientational ordering of water molecules results in a significant electrostatic potential around the surface of MPAN. 27 Weng and co-workers 29,30 showed that both terminal groups and side chains of SAMs have a considerable influence on the interfacial HB network and the residence time of water molecules near the nanoparticle surface. The terminal carboxyl, hydroxyl, and amine groups can form interfacial HBs with the neighboring water molecules, which results in a weakening HB strength between water molecules.…”

Section: Introductionmentioning

confidence: 99%

“…29 Moreover, they found stronger interfacial HB networks can lead to an increase of the residence time of interfacial water molecules. 29,30 More recently, Akola and co-workers 32 focused on the effect of electrostatic potential on the interfacial properties of charged MPAN with amine (NH + 3 ) and carboxyl (COO − ) terminal groups and Na + /Cl − counterions in aqueous environment. The radial electrostatic potential distribution of anionic MPAN was found to significantly differ from that of cationic MPAN, resulting in a noticeable difference in the average number, structure, and lifetime of interfacial HBs between the two MPANs.…”

Section: Introductionmentioning

confidence: 99%

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Insights into hydrogen bond dynamics at the interface of the charged monolayer-protected Au nanoparticle from molecular dynamics simulation

Li¹,

Yang²,

Hu³

et al. 2013

The Journal of Chemical Physics

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The structure and dynamics properties of water molecules at the interface of the charged monolayer-protected Au nanoparticle (MPAN) have been investigated in detail by using classical molecular dynamics simulation. The simulation results demonstrated clearly that a well-defined hydration layer is formed at the interface of MPAN and a stable "ion wall" consisting of terminal NH3 (+) groups and Cl(-) counterions exists at the outmost region of self-assembled monolayer (SAM) where the translational and rotational motions of water molecules slow considerably down compared to those in the bulk owing to the presence of SAM and ion wall. Furthermore, we found that the translational motions of interfacial water molecules display a subdiffusive behavior while their rotational motions exhibit a nonexponential feature. The unique behavior of interfacial water molecules around the MPAN can be attributed to the interfacial hydrogen bond (HB) dynamics. By comparison, the lifetime of NH3 (+)-Cl(-) HBs was found to be the longest, favoring the stability of ion wall. Meanwhile, the lifetime of H2O-H2O HBs shows an obvious increase when the water molecules approach the Au core, suggesting the enhanced H2O-H2O HBs around the charged MPAN, which is contrary to the weaken H2O-H2O HBs around the neutral MPAN. Moreover, the HB lifetimes between water molecules and the ion wall (i.e., the Cl(-)-H2O and NH3 (+)-H2O HBs) are much longer than that of interfacial H2O-H2O HBs, which leads to the increasing rotational relaxation time and residence time of water molecules surrounding the ion wall. In addition, the corresponding binding energies for different HB types obtained from the precise density functional theory are in excellent accordance with above simulation results. The detailed HB dynamics studied in this work provides insights into the unique behavior of water molecules at the interface of charged self-assemblies of nanoparticles as well as proteins.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Insights into hydrogen bond dynamics at the interface of the charged monolayer-protected Au nanoparticle from molecular dynamics simulation

Li¹,

Yang²,

Hu³

et al. 2013

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…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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Solvent‐driven symmetry of self‐assembled nanocrystal superlattices—A computational study

Kaushik

Clancy

2012

J Comput Chem

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The preference of experimentally realistic sized 4-nm facetted nanocrystals (NCs), emulating Pb chalcogenide quantum dots, to spontaneously choose a crystal habit for NC superlattices (Face Centered Cubic (FCC) vs. Body Centered Cubic (BCC)) is investigated using molecular simulation approaches. Molecular dynamics simulations, using united atom force fields, are conducted to simulate systems comprised of cube-octahedral-shaped NCs covered by alkyl ligands, in the absence and presence of experimentally used solvents, toluene and hexane. System sizes in the 400,000-500,000-atom scale followed for nanoseconds are required for this computationally intensive study. The key questions addressed here concern the thermodynamic stability of the superlattice and its preference of symmetry, as we vary the ligand length of the chains, from 9 to 24 -CH(2) groups, and the choice of solvent. We find that hexane and toluene are "good" solvents for the NCs, which penetrate the ligand corona all the way to the NC surfaces. We determine the free energy difference between FCC and BCC NC superlattice symmetries to determine the system's preference for either geometry, as the ratio of the length of the ligand to the diameter of the NC is varied. We explain these preferences in terms of different mechanisms in play, whose relative strength determines the overall choice of geometry.

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Behavior of water molecules near monolayer-protected clusters with different terminal segments of ligand

Cited by 16 publications

References 29 publications

Insights into hydrogen bond dynamics at the interface of the charged monolayer-protected Au nanoparticle from molecular dynamics simulation

Insights into hydrogen bond dynamics at the interface of the charged monolayer-protected Au nanoparticle from molecular dynamics simulation

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

Solvent‐driven symmetry of self‐assembled nanocrystal superlattices—A computational study

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