Structure and self-assembly of sequentially adsorbed coronene/octanethiol monolayers

Raigoza, Annette F.; Villalba, D. Andres; Kautz, Natalie A.; Kandel, S. Alex

doi:10.1016/j.susc.2010.05.029

Cited by 16 publications

(17 citation statements)

References 84 publications

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“…The metal‐coronene interactions, like coronene‐to‐coronene π–π stackings, were particularly dominating, depending on the electronic nature of different metal surfaces such as Ag(111), Au(111), Cu(110), [140] and even silica surface, as evidenced by DFT and MP2 methods [141] . At different metal surfaces, coronene could exist in the form of isolated molecules, clusters, or others, which were studied by the spectroscopic and other techniques [142–144] . Coronene monolayers have also been visualized and characterized [145–147] .…”

Section: Resultsmentioning

confidence: 99%

Coronenes, Benzocoronenes and Beyond: Modern Aspects of Their Syntheses, Properties, and Applications

Kumar

Tao

2021

Chemistry An Asian Journal

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In recent years, a variety of new designs of coronene‐based polycyclic aromatic hydrocarbons (PAHs) with diverse functions have emerged to serve as complementary materials in organic chemistry and materials chemistry. In the present review, we highlight the modern aspects of syntheses related to or different from the strategies used in the early era of coronene research. Systematic extension and expansion of coronene backbones to wide categories of angular PAHs are covered. The substitution and extension of coronene architectures, by incorporating functional groups and by fusing small and large conjugated units, advatangeously enrich their photophysical, electrochemical, self‐assembling, and other properties, of which are discussed to demostrate their impact in materials chemistry. While the highly symmetric coronenes, tribenzocoronenes and hexabenzocoronenes conceived wide potential in charge‐transporting, electroluminescent, sensing, and other applications, other related derivatives such as dibenzo, tetrabenzo and pentabenzocoronenes also displayed their potentials as exemplified by their use as charge‐conduction channel in transistor application.

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Section: Resultsmentioning

confidence: 99%

Coronenes, Benzocoronenes and Beyond: Modern Aspects of Their Syntheses, Properties, and Applications

Kumar

Tao

2021

Chemistry An Asian Journal

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“…In general, NCs were synthesized by chemical solution-phase colloidal routes to achieve controlled size distribution and chemical stability. This colloidal stabilization can be accomplished by a self-assembled monolayer (SAM) of organic ligand molecules, [6][7][8][9] that bind to the metal NC surfaces through a strong thiol-metal bond. The protecting monolayer can prevent coagulation and increase dispersion stability in solvent media.…”

Section: Introductionmentioning

confidence: 99%

Molecular simulation of interaction between passivated gold nanoparticles in supercritical CO2

Sun

Yang

et al. 2011

The Journal of Chemical Physics

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Molecular dynamics simulations have been performed to study the potential of mean force (PMF) between passivated gold nanoparticles (NPs) in supercritical CO(2) (scCO(2)). The nanoparticle model consists of a 140 atom gold nanocore and a surface self-assembled monolayer, in which two kinds of fluorinated alkanethiols were considered. The molecular origin of the thermodynamics interaction and the solvation effect has been comprehensively studied. The simulation results demonstrate that increasing the solvent density and ligand length can enhance the repulsive feature of the free energy between the passivated Au nanoparticles in scCO(2), which is in good agreement with previous experimental results. The interaction forces between the two passivated NPs have been decomposed to reveal various contributions to the free energy. It was revealed that the interaction between capping ligands and the interaction between the capping ligands and scCO(2) solvent molecules cooperatively determine the total PMF. A thermodynamic entropy-energy analysis for each PMF contribution was used to explain the density dependence of PMF in scCO(2) fluid. Our simulation study is expected to provide a novel microscopic understanding of the effect of scCO(2) solvent on the interaction between passivated Au nanoparticles, which is helpful to the dispersion and preparation of functional metal nanoparticles in supercritical fluids.

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“…3d); (3) junction formation avoids migration from isolated high-coordination terrace sites (for more on these types of putative highenergy structures, see Supporting Information section S2.2). The unusually high stability of alkanethiolate-Au at kinks on step edge sites indicates that these naturally-occurring and ubiquitous [28][29][30][31] step edge defects provide low-energy paths for migration with E b = + (0.4 -0.7) eV, Figure 3d. Note that bare Au has a relatively low E b of +0.7 eV on step edges but this rises to +0.8 eV and more sharply to +1.2 eV for migration bridging step edge and, respectively, ridge and terrace sites, emphasizing the stabilizing effect of the coordinating alkanethiolate.…”

Section: Resultsmentioning

confidence: 99%

“…Hence, the small Au 20 clusters allowed us to perform a large number of detailed calculations to track the migration path of gold atoms from a variety of surface binding sites (as described in section Crumbling, atomic migration and sculpting of gold clusters below). Since Au 20 is a molecular cluster with a HOMO-LUMO gap, a separate periodic slab model of Au(111) that maintains the metallicity of the surface was used to measure migration of Au atoms on the gold surface.These periodic simulation cells include a range of experimentally-observed, naturally-occurring surface features (see ref[28][29][30][31] and references cited therein) such as terraces, step edges and ridges, and provide a realistic extended surface model on which to compute gold atom migration barriers.A second set of periodic models were used to include the bound alkanethiolate molecule and allow a direct calculation of the effect of alkanethiolate binding on gold atom migration and the migration barrier for the alkanethiolate-Au moiety on the gold surface.Figure 2shows illustrative examples of the surface models used to calculate the energetics of Au atom and alkanethiolate-Au species migration paths on Au(111). We find barriers E b of 0.4-0.7 eV, consistent with the experimental E a , for the migration of alkanethiolate-Au species along step edges.…”

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confidence: 99%

Formation Mechanism of Metal–Molecule–Metal Junctions: Molecule-Assisted Migration on Metal Defects

et al. 2015

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Activation energies E a measured from molecular exchange experiments are combined with atomic-scale calculations to describe the migration of bare Au atoms and Au-alkanethiolate species on gold nanoparticle surfaces during ligand exchange for the creation of metal-molecule-metal junctions. It is well known that Au atoms and alkanethiol-Au species can diffuse on gold with sub-1 eV barriers, and surface restructuring is crucial for self-assembled monolayer (SAM) formation, for interlinking nanoparticles and in contacting nanoparticles to electrodes. In the present work, computer simulations reveal that naturally occurring ridges and adlayers on Au(111) are etched and resculpted by migration of alkanethiolate-Au species towards high coordination kink sites at surface step edges. The calculated energy barrier E b for diffusion via step edges is 0.4-0.7 eV, close to the experimentally-measured E a of 0.5-0.7 eV. By contrast, putative migration from isolated nine-coordinated terrace sites and complete Au unbinding from the surface incur significantly larger barriers of +1 and +3 eV, respectively. Molecular van der Waals's packing energies are calculated to have negligible effect on migration barriers for typically-used molecules (length < 2.5nm), indicating that migration inside SAMs does not change the size of the migration barrier. We use the computational methodology to propose a means of creating Au nanoparticle arrays via selective replacement of citrate protector molecules by thiocyanate linker molecules on surface step sites. This work also outlines the possibility of using Au/Pt alloys as possible candidates for creation of contacts that are well-formed and long-lived, due to the superior stability of Pt interfaces against atomic migration.

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Structure and self-assembly of sequentially adsorbed coronene/octanethiol monolayers

Cited by 16 publications

References 84 publications

Coronenes, Benzocoronenes and Beyond: Modern Aspects of Their Syntheses, Properties, and Applications

Coronenes, Benzocoronenes and Beyond: Modern Aspects of Their Syntheses, Properties, and Applications

Molecular simulation of interaction between passivated gold nanoparticles in supercritical CO2

Formation Mechanism of Metal–Molecule–Metal Junctions: Molecule-Assisted Migration on Metal Defects

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