Atomistic Simulations of Self-Assembled Monolayers on Octahedral and Cubic Gold Nanocrystals

Abstract

International audienceThis paper reports on a molecular dynamics investigation of the molecular organization of alkanethiolates (from ethane to dodecanethiolate) on octahedral and cubic gold nanocrystals with diameters up to 10 nm. We show that the average surface per adsorbed thiolate only slightly depends on the nanocrystal shape and the alkane chain length. Two different organizations of thiolates are observed on the facet centers and edges of octahedral nanocrystals, while on cubic nanocrystals only one appears. This explains the closer distance between thiolates on the edges of octahedral nanocrystals, which is not observed for nanocubes. The enhanced surface coverage of thiolates on nanocrystals is explained by the new organization for octahedral nanocrystals and can be attributed to the occupation of adsorption sites on the edges for cubic nanocrystals. Small differences observed in the molecular organizations on icosahedral and octahedral nanocrystals can be mainly explained by the larger facets of the latter ones

Full Atomistic Simulation of Cross-Linked Gold Nanoparticle Assemblies

“…We also investigate the binding sites and find that the sulfur head groups mainly occupy the threefold hollow and bridge binding sites on Au(111) facets, while occupying the fourfold hollow binding sites on Au(100) facets. The results are similar to the previous simulation study [36].…”

Structural Characterization of Alkylsilane and Fluoroalkylsilane Self-Assembled Monolayers on SiO2 by Molecular Dynamics Simulations

“…The recent simulation literature on octadecyl SAMs on metal surfaces is quite abundant, in particular with many studies by Saha and coworkers describing the SAM stability and its dynamics at different partial coverages on gold substrates. [27][28][29][30][31] Turning to SiO 2 surfaces, alkoxysilane-coated SiO 2 nanoparticles have been simulated both in vacuum 32 and in alkane solvents; 26 Ewers and Batteas also studied functionalized silica interfaces, focusing on the modification of friction and attractive forces introduced by OTS coatings. 33 and forming, to mimic the SAM formation process, 36 but obtaining tilt angles quite far from experimental estimates.…”

Atomic Structure of Self-Assembled Monolayer of Thiolates on a Tetragonal Au92 Nanocrystal

“… These generalized structural models define a new category of faceted nanocrystals, as opposed to the staple-motif-based nonfaceted nanoclusters (e.g., spheres, spheroids, etc. ). ,,, The models are also important for understanding the facet development, shape control, and edge/corner effects in larger nanoparticles (e.g., >1000 gold atoms), − whose structures are by far still difficult to solve by X-ray crystallography …”