Forming Aromatic Hemispheres on Transition‐Metal Surfaces

Rim, Kwang Taeg; Siaj, Mohamed; Xiao, Shengxiong; Myers, Matthew; Carpentier, Vincent D.; Liu, Li; Su, Chun; Steigerwald, Michael L.; Hybertsen, Mark S.; McBreen, Peter H.; Flynn, George W.; Nuckolls, Colin

doi:10.1002/anie.200701117

Cited by 79 publications

(42 citation statements)

References 36 publications

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“…Aside from graphene growth using different aromatic source molecules discussed above222324, here we also briefly discuss the potential broader applicability of the main findings in the fabrication of other nanostructures catalyzed on transition metal substrates as reported recently373839. A closer comparison between these seemingly very different systems leads to the recognition of several essential conceptual similarities.…”

Section: Discussionmentioning

confidence: 80%

Drastic reduction in the growth temperature of graphene on copper via enhanced London dispersion force

Choi

Cui

et al. 2013

Sci Rep

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London dispersion force is ubiquitous in nature, and is increasingly recognized to be an important factor in a variety of surface processes. Here we demonstrate unambiguously the decisive role of London dispersion force in non-equilibrium growth of ordered nanostructures on metal substrates using aromatic source molecules. Our first-principles based multi-scale modeling shows that a drastic reduction in the growth temperature, from ,10006C to ,3006C, can be achieved in graphene growth on Cu(111) when the typical carbon source of methane is replaced by benzene or p-Terphenyl. The London dispersion force enhances their adsorption energies by about (0.5-1.8) eV, thereby preventing their easy desorption, facilitating dehydrogenation, and promoting graphene growth at much lower temperatures. These quantitative predictions are validated in our experimental tests, showing convincing demonstration of monolayer graphene growth using the p-Terphenyl source. The general trends established are also more broadly applicable in molecular synthesis of surface-based nanostructures. , and molecular assembly at surfaces 6,7 . To a large extent, such advances through quantitative definitive studies were enabled by the availability of more accurate descriptions of the weak interactions associated with long-range electron correlation effects within first-principles approaches [8][9][10] . In this study, we exploit the power of predictive modeling using state-of-the-art first-principles calculations within density functional theory (DFT), coupled with kinetic rate equation analysis and definitive experimental tests, to establish unambiguously the decisive role of London dispersion force in molecular self-assembly of aromatic source molecules. We choose graphene growth on Cu substrates as an important class of prototypical model systems, and the microscopic mechanisms revealed are broadly applicable in other nanofabrication processes via molecular assembly.Because of its exotic electronic properties [11][12][13][14][15]

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Section: Discussionmentioning

confidence: 80%

Drastic reduction in the growth temperature of graphene on copper via enhanced London dispersion force

Choi

Cui

et al. 2013

Sci Rep

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“…41 When 1 is formed as a submonolayer on ruthenium, we observe the molecule flattening to make contact with the metal, but it is unable to become completely planar and has one arm that remains out the plane of the core (Figure 12). 42 We observe hemispheric HBCs, resulting from the formation of six 5-membered rings, by applying heat to a submonolayer of cHBCs on ruthenium ( Figure 12). This hemispheric form for 1 is significant because of its potential to act as a seed for carbon nanotube growth with a specific chirality and diameter.…”

Section: Accounts Of Chemical Researchmentioning

confidence: 95%

Contorted Polycyclic Aromatics

et al. 2014

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CONSPECTUS: This Account describes a body of research in the design, synthesis, and assembly of molecular materials made from strained polycyclic aromatic molecules. The strain in the molecular subunits severely distorts the aromatic molecules away from planarity. We coined the term "contorted aromatics" to describe this class of molecules. Using these molecules, we demonstrate that the curved pi-surfaces are useful as subunits to make self-assembled electronic materials. We have created and continue to study two broad classes of these "contorted aromatics": discs and ribbons. The figure that accompanies this conspectus displays the three-dimensional surfaces of a selection of these "contorted aromatics". The disc-shaped contorted molecules have well-defined conformations that create concave pi-surfaces. When these disc-shaped molecules are substituted with hydrocarbon side chains, they self-assemble into columnar superstructures. Depending on the hydrocarbon substitution, they form either liquid crystalline films or macroscopic cables. In both cases, the columnar structures are photoconductive and form p-type, hole- transporting materials in field effect transistor devices. This columnar motif is robust, allowing us to form monolayers of these columns attached to the surface of dielectrics such as silicon oxide. We use ultrathin point contacts made from individual single-walled carbon nanotubes that are separated by a few nanometers to probe the electronic properties of short stacks of a few contorted discs. We find that these materials have high mobility and can sense electron-deficient aromatic molecules. The concave surfaces of these disc-shaped contorted molecules form ideal receptors for the molecular recognition and assembly with spherical molecules such as fullerenes. These interfaces resemble ball-and-socket joints, where the fullerene nests itself in the concave surface of the contorted disc. The tightness of the binding between the two partners can be increased by creating more hemispherically shaped contorted molecules. Given the electronic structure of these contorted discs and the fullerenes, this junction is a molecular version of a p-n junction. These ball-and-socket interfaces are ideal for photoinduced charge separation. Photovoltaic devices containing these molecular recognition elements demonstrate approximately two orders of magnitude increase in charge separation. The ribbon-shaped, contorted molecules can be conceptualized as ultranarrow pieces of graphene. The contortion causes them to wind into helical ribbons. These ribbons can be formed into the active layer of field effect transistors. We substitute the ribbons with di-imides and therefore are able to transport electrons. Furthermore, these materials absorb light strongly and have ideal energetic alignment of their orbitals with conventional p-type electronic polymers. In solar cells, these contorted ribbons with commercial donor polymers have record efficiencies for non-fullerene-based solar cells. An area of interest for future explo...

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“…Therefore, the synthesis of fullerenes requires harder conditions, including using more reactive Pt-group metal surfaces and applying higher temperatures of 450-600°C [33]. The first surface-assisted synthesis of the bowl-shaped PAH was reported by Rim et al on the example of the hemispherical PAH C 48 , which was generated on the Ru(0001) surface via exhaustive cyclodehydrogenation of hexabenzocoronene precursor ( Figure 5) [34]. The six-fold cyclodehydrogenation on the periphery of precursor was achieved by annealing of the precursor molecule at 600°C.…”

Section: Surface-assisted Synthesismentioning

confidence: 99%

“…However, due to high reactivity of the Ru surface and high temperature applied, the dehydrogenation process does not stop on the formation of the C 48 H 12 bowl. The bowl-shaped PAH undergoes further dehydrogenation resulting in allcarbon C 48 bowl covalently bonded to the Ru surface by 12 C─Ru bonds ( Figure 5) [34].…”

Section: Surface-assisted Synthesismentioning

confidence: 99%

Rational Synthesis of Fullerenes

Amsharov¹

2018

Fullerenes and Relative Materials - Properties and Applications

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Fullerenes are a unique family of carbon-based cage molecules, which attract interest because of their remarkable properties and potential applications. Most effort so far has been focused on the study of C 60 and C 70 , whereas other members of the huge fullerene family remain poorly explored. One of the main challenges in this field is the developing of the synthetic methods, which are suitable for the production of these unique materials in isomer-pure form in macroscopic amounts. Here, we review studies toward the rational synthesis of fullerenes from molecular precursors that have been published to date. The scope and limitation of the zipping strategy are discussed. The relevance and prospects for construction of the fullerene cages and related carbon-based nanostructures via cyclodehydrofluorination (C─F bond activation) are highlighted.

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Forming Aromatic Hemispheres on Transition‐Metal Surfaces

Cited by 79 publications

References 36 publications

Drastic reduction in the growth temperature of graphene on copper via enhanced London dispersion force

Drastic reduction in the growth temperature of graphene on copper via enhanced London dispersion force

Contorted Polycyclic Aromatics

Rational Synthesis of Fullerenes

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