Crystal Structures of Molecular Gold Nanocrystal Arrays

Whetten, Robert L.; Shafigullin, Marat N.; Khoury, Joseph T.; Schaaff, T. Gregory; Vezmar, Igor; Alvarez, and Marcos M.; Wilkinson, Angus P.

doi:10.1021/ar970239t

Cited by 583 publications

(647 citation statements)

References 38 publications

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“…In 3D structures on the other hand, the typical distance between adjacent NCs depends on the ligand length due to the limited available volume, and our golden rule does not apply. 5,62 The universal equilibrium distance of 1.25d c only makes sense if the ligand is sufficiently long; if L Ͻ 1.25d c − d c / 2, then the capping layers are not in contact when the NCs are at distance r = 1.25d c . We computed the PMFs for a larger NC Au 1415 ͑d c = 3.7 nm͒ capped by very short ligands SC 2 and SC 3 and compared them to the ones for longer SC 6 and SC 12 capping molecules, see Fig.…”

Section: Pair Interactionsmentioning

confidence: 99%

“…1 These NCs can self-assemble in a range of different two-dimensional ͑2D͒ and three-dimensional ͑3D͒ superstructures. [2][3][4][5] NCs are usually protected by an organic capping layer that prevents aggregation, e.g., gold NCs are often capped with alkyl thiol molecules. 6 These capping molecules ͑also referred to as surfactants or ligands͒ play an important role in the selfassembly of NCs.…”

Section: Introductionmentioning

confidence: 99%

“…The ratio between the core diameter ͑d c ͒ and surfactant chain length ͑L͒ determines the crystal structure of a Au NC superlattice. 5,7 Capping exchange can alter the crystal structure of a binary superlattice. 8 Moreover, due to the attractive interactions between capping molecules, in binary NC systems, crystal structures with high coordination form rather than the ones with a higher packing fraction.…”

Section: Introductionmentioning

confidence: 99%

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Understanding interactions between capped nanocrystals: Three-body and chain packing effects

Schapotschnikow

Vlugt

2009

The Journal of Chemical Physics

152

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Self-assembly of capped nanocrystals ͑NC͒ attracted a lot of attention over the past decade. Despite progress in manufacturing of NC superstructures, the current understanding of their mechanical and thermodynamic stability is still limited. For further applications, it is crucial to find the origin and the magnitude of the interactions that keep self-assembled NCs together, and it is desirable to find a way to rationally manipulate these interactions. We report on molecular simulations of interacting gold NCs protected by capping molecules. We computed the potential of mean force for pairs and triplets of NCs of different size ͑1.8-3.7 nm͒ with varying ligand length ͑ethanethiol-dodecanethiol͒ in vacuum. Pair interactions are strongly attractive due to attractive van der Waals interactions between ligand molecules. Three-body interaction results in an energy penalty when the capping layers overlap pairwise. This effect contributes up to 20% to the total energy for short ligands. For longer ligands, the three-body effects are so large that formation of NC chains becomes energetically more favorable than close packing of capped NCs at low concentrations, in line with experimental observations. To explain the equilibrium distance for two or more NCs, the overlap cone model is introduced. This model is based on relatively simple ligand packing arguments. In particular, it can correctly explain why the equilibrium distance for a pair of capped NCs is always Ϸ1.25 times the core diameter independently on the ligand length, as found in our previous work ͓Schapotschnikow, R. Pool, and T. J. H. Vlugt, Nano Lett. 8, 2930 ͑2008͔͒. We make predictions for which ligands capped NCs self-assemble into highly stable three-dimensional structures, and for which they form high-quality monolayers.

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Section: Pair Interactionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Understanding interactions between capped nanocrystals: Three-body and chain packing effects

Schapotschnikow

Vlugt

2009

The Journal of Chemical Physics

152

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“…As noted above, these include the BCC lattice with two peaks at short distances (Fig. 9) but also the anisotropic variants such as the BCT lattice 35 where the 6 BCC second-shell sites are split into a subshell of 4 sites and a subshell of 2 sites, and the BCO lattice 10 where the fourfold BCT next-to-nearest-neighbor subshell is further split in two subshells. (Curiously, the anisotropic version of the FCC lattice -the face-centered orthorombic (FCO) structure has not yet been observed in a colloidal or related system.)…”

Section: Short-range Potentials and Solid-solid Phase Transitionsmentioning

confidence: 99%

Maximizing Entropy by Minimizing Area: Towards a New Principle of Self-Organization

2001

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We propose a heuristic explanation for the numerous non-close-packed crystal structures observed in various colloidal systems. By developing an analogy between soap froths and the soft coronas of fuzzy colloids, we provide a geometrical interpretation of the free energy of soft spheres. Within this picture, we show that the close-packing rule associated with hard-core interaction and positional entropy of particles is frustrated by a minimum-area principle associated with the soft tail and internal entropy of the soft coronas. We also discuss these ideas in terms of crystal architecture and pair distribution functions and analyze the phase diagram of a model hard-sphere-square-shoulder system within the cellular theory. We find that the A15 lattice, known to be area minimizing, is favored for a reasonable range of model parameters and so it is among the possible equilibrium states for a variety of colloidal systems. We also show that in the case of short-range convex potentials the A15 and other non-close-packed lattices coexist over a broad ranges of densities, which could make their identification difficult.

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“…Metal thiolates are an important class of compounds because of their structural diversity in coordination chemistry, [1][2][3] relevance to cofactors of metalloproteins in biological systems, [4][5] and importance in cluster and surface science [6][7] and catalysis. 8 Thiolate-bridged polynuclear group 10 transition-metal complexes with chain structures, [M(-SR) 2 ] n (M = Ni, Pd), have been investigated in detail because they provide efficient catalysis of atom-economical organic reactions such as regioselective additions of thiols and disulfides across alkynes.…”

Section: Introductionmentioning

confidence: 99%

Tiara-like Octanuclear Palladium(II) and Platinum(II) Thiolates and Their Inclusion Complexes with Dihalo- or Iodoalkanes

2014

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A tiara-like octanuclear palladium thiolate complex, [Pd(-SCH 2 CO 2 Me) 2 ] 8 that has a toroidal structure, was synthesized via reactions of either PdCl 2 with methyl thioglycolate/N,N-diisopropylethylamine (DIEA) (conventional method) or [PdCl 2 (MeCN) 2 ] with m-C 6 H 4 (CMe 2 SCH 2 CO 2 Me) 2 (alternative method). In the latter method, the tiara-like complex formed via the corresponding SCS-pincer complex and/or 1:1 PdCl 2 and ligand complexes. With respect to the platinum analogs, the alternative method efficiently produced the tiara-like octanuclear complex, [Pt(-SCH 2 CO 2 Me) 2 ] 8 , in high purity. Small molecules, such as CH 2 Cl 2 , ClCH 2 CH 2 Cl, CH 2 Br 2 , and CH 3 I, were accommodated in the inner voids of the tiara rings to form 1:1 inclusion complexes. These complexes are stabilized by weak CH···X hydrogen bonds (X = Cl or Br) between the methylene protons of four or eight axially positioned methoxycarbonylmethyl groups on the tiara rings and the halogen atoms of the guest molecules, as well as weak coordination of the halogen atoms to the transition-metal atoms.2

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Crystal Structures of Molecular Gold Nanocrystal Arrays

Cited by 583 publications

References 38 publications

Understanding interactions between capped nanocrystals: Three-body and chain packing effects

Understanding interactions between capped nanocrystals: Three-body and chain packing effects

Maximizing Entropy by Minimizing Area: Towards a New Principle of Self-Organization

Tiara-like Octanuclear Palladium(II) and Platinum(II) Thiolates and Their Inclusion Complexes with Dihalo- or Iodoalkanes

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