Chiral Monolayers at the Air‐Water Interface

Stewart, M.; Arnett, Edward M.

doi:10.1002/9780470147221.ch3

Cited by 42 publications

(3 citation statements)

References 192 publications

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“…12 Moreover, it has been predicted that 2D enantioseparation on a surface should occur more easily than in three-dimensional (3D) crystals. 13 Because of confinement in the plane certain symmetry elements, like center of inversion or the glide plane parallel to the surface, are precluded, 14 and a higher probability for spontaneous resolution is therefore expected. 15 Here we present a STM study on the 2D crystallization of the chiral aromatic hydrocarbon heptahelicene (Figure 1, C 30 H 18 , [7]H) on a Cu(111) surface.…”

Section: Introductionmentioning

confidence: 99%

Coverage and Enantiomeric Excess Dependent Enantiomorphism in Two-Dimensional Molecular Crystals

Parschau

Fasel

Ernst

2008

Crystal Growth & Design

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The question of racemate versus conglomerate stability is tremendously important for chiral resolution via crystallization methods. Scanning tunneling microscopic studies with molecular resolution on two-dimensional (2D) model systems contribute at large to solve problems on complex crystallization phenomena. The dependence of lattice polymorphism and enantiomorphism on coverage and enantiomeric excess has been investigated for monolayers of enantiopure and racemic heptahelicene on a Cu(111) surface in ultrahigh vacuum. The densest packing is achieved in a homochiral lattice structure. This should favor 2D conglomerate formation for the racemate, since a higher coverage leads to an overall lower energy. However, only heterochiral structures are observed. Small enantiomeric excess (ee) induces lattice homochirality by suppressing one enantiomorph. At larger ee, we observe crystals disordered at the molecular level. Long-range ordered homochiral structures are suppressed due to small chiral impurities. The preference of a 2D racemic compound formation, the induction of lattice homochirality at small ee, and the solid solution formation at larger ee are discussed in the light of energetic, entropic, and kinetics effects.

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Section: Introductionmentioning

confidence: 99%

Coverage and Enantiomeric Excess Dependent Enantiomorphism in Two-Dimensional Molecular Crystals

Parschau

Fasel

Ernst

2008

Crystal Growth & Design

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“…The proportion of twodimensional chiral space groups (five chiral space groups of the 17 available, 29.4%) is very similar to that in three-dimensional (3D) systems (65 space groups of the 230 available, 28.3%), but the spontaneous separation of enantiomers of both chiral and achiral molecules at ordered surfaces is frequent [26,27]. This situation can be rationalized by taking into account the mutual symmetry relations that adsorbate and surface must satisfy [28,29]. A molecule confined in a monolayer on a surface cannot be related to another by inversion symmetry, and the glide plane parallel to the surface is similarly excluded.…”

Section: Chiral Monolayersmentioning

confidence: 99%

Monolayer self-assembly at liquid–solid interfaces: chirality and electronic properties of molecules at surfaces

Amabilino

Feyter

Lazzaroni

et al. 2008

J. Phys.: Condens. Matter

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The spontaneous formation of supramolecular assemblies at the boundary between solids and liquids is a process which encompasses a variety of systems with diverse characteristics: chemisorbed systems in which very strong and weakly reversible bonds govern the assembly and physisorbed aggregates which are dynamic thanks to the weaker interactions between adsorbate and surface. Here we review the interest and advances in the study of chiral systems at the liquid-solid interface, and also the application of this configuration for the study of systems of interest in molecular electronics, self-assembled from the bottom up.

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“…Analogous alternatives arise when molecules that are chiral in 2D are adsorbed on surfaces. Earlier studies of this phenomenon have suggested that racemic crystals are less predominant in 2D than in 3D, − ,− but no clear consensus about the generality of these data has emerged, and the reasons for significantly different behavior in 2D and 3D have not been fully delineated. Molecular chirality has widespread consequences in nature, and adsorption on surfaces to create chiral patterns may have been a critical step in the origin of life.…”

Section: Introductionmentioning

confidence: 99%

Crankshafts: Using Simple, FlatC_2h-Symmetric Molecules to Direct the Assembly of Chiral 2D Nanopatterns

Zhou

Wuest

2012

Langmuir

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Linear D2h-symmetric bisisophthalic acids 1 and 2 and related substances have well-defined flattened structures, high affinities for graphite, and strong abilities to engage in specific intermolecular interactions. Their adsorption produces characteristic nanopatterns that reveal how 2D molecular organization can be controlled by reliable interadsorbate interactions such as hydrogen bonds when properly oriented by molecular geometry. In addition, the behavior of these compounds shows how large-scale organization can be obstructed by programming molecules to associate strongly according to competing motifs that have similar stability and can coexist smoothly without creating significant defects. Analogous new bisisophthalic acids 3a and 4a have similar associative properties, and their unique C2h-symmetric crankshaft geometry gives them the added ability to probe the poorly understood effect of chirality on molecular organization. Their adsorption shows how nanopatterns composed predictably of a single enantiomer can be obtained by depositing molecules that can respect established rules of association only by accepting neighbors of the same configuration. In addition, an analysis of the adsorption of crankshaft compounds 3a and 4a and their derivatives by STM reveals directly on the molecular level how kinetics and thermodynamics compete to control the crystallization of chiral compounds. In such ways, detailed studies of the adsorption of properly designed compounds on surfaces are proving to be a powerful way to discover and test rules that broadly govern molecular organization in both 2D and 3D.

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Chiral Monolayers at the Air‐Water Interface

Cited by 42 publications

References 192 publications

Coverage and Enantiomeric Excess Dependent Enantiomorphism in Two-Dimensional Molecular Crystals

Coverage and Enantiomeric Excess Dependent Enantiomorphism in Two-Dimensional Molecular Crystals

Monolayer self-assembly at liquid–solid interfaces: chirality and electronic properties of molecules at surfaces

Crankshafts: Using Simple, FlatC_2h-Symmetric Molecules to Direct the Assembly of Chiral 2D Nanopatterns

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Chiral Monolayers at the Air‐Water Interface

Cited by 42 publications

References 192 publications

Coverage and Enantiomeric Excess Dependent Enantiomorphism in Two-Dimensional Molecular Crystals

Coverage and Enantiomeric Excess Dependent Enantiomorphism in Two-Dimensional Molecular Crystals

Monolayer self-assembly at liquid–solid interfaces: chirality and electronic properties of molecules at surfaces

Crankshafts: Using Simple, FlatC2h-Symmetric Molecules to Direct the Assembly of Chiral 2D Nanopatterns

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Crankshafts: Using Simple, FlatC_2h-Symmetric Molecules to Direct the Assembly of Chiral 2D Nanopatterns