Orientation of chiral heptahelicene C30H18 on copper surfaces: An x-ray photoelectron diffraction study

Fasel, Román; Cossy, A.; Ernst, Karl‐Heinz; Baumberger, F.; Greber, Thomas; Osterwalder, Jürg

doi:10.1063/1.1377886

Cited by 85 publications

(88 citation statements)

References 33 publications

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“…The Menantiomer shows the corresponding mirror structures, i.e., with opposite handedness (not shown) [122]. XPD revealed that three rings on the proximal end are aligned parallel to the surface plane [35], and force-field calculations for the saturation structure provided a model in good agreement with the observations (Fig. 20c and d).…”

Section: Racemic Mixturessupporting

confidence: 74%

“…5) [34]. The same method delivered the absolute helicity of heptahelicene after uniform alignment on the terraces of a Cu(332) surface [35] and was later confirmed by comparing calculated and measured vibrational circular dichroism spectra [36], i.e., the differential absorption of circular polarized IR light.…”

Section: Absolute Configuration and Stereodescriptorsmentioning

confidence: 90%

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Molecular chirality at surfaces

Ernst

2012

Physica Status Solidi (b)

223

264

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With the adsorption of larger molecules being increasingly tackled by surface scientists, the aspect of chirality often plays a role. This paper gives a topical review of molecular chirality at surfaces and gives a phenomenological overview of different aspects of adsorption and self‐assembly of chiral and prochiral molecules and the principles of mirror‐symmetry breaking at a surface. After a brief introduction into the history of molecular chirality and the important role it played for understanding the spatial structure of molecules, definitions of chirality are presented. Topics treated here are principle ways to create single chiral adsorbates, chiral ensembles, and monolayers by achiral molecules, adsorption of intrinsically chiral molecules at achiral and chiral surfaces, long‐range symmetry breaking in two‐dimensional (2D) crystals due to additional chiral bias, chiral restructuring of solid surfaces under the influence of chiral molecules, switching the handedness of adsorbates, and chirality at the liquid/air interface. An outlook onto further potential research directions and recommendations for further reading, including nonsurface‐related sources of chiral topics completes this paper.

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Section: Racemic Mixturessupporting

confidence: 74%

Section: Absolute Configuration and Stereodescriptorsmentioning

confidence: 90%

Molecular chirality at surfaces

Ernst

2012

Physica Status Solidi (b)

223

264

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“…[1][2][3][4][5][6][7][8][9] Recent investigations employing the scanning tunneling microscope revealed that this issue can be addressed successfully at the single molecule level with adsorbed species at solid surfaces. There are several aspects to chirality at surfaces.…”

Section: Introductionmentioning

confidence: 99%

Stereochemical Effects in Supramolecular Self-Assembly at Surfaces: 1-D versus 2-D Enantiomorphic Ordering for PVBA and PEBA on Ag(111)

et al. 2002

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Abstract:We present investigations on noncovalent bonding and supramolecular self-assembly of two related molecular building blocks at a noble metal surface: 4-[trans-2-(pyrid-4-yl-vinyl)]benzoic acid (PVBA) and 4-[(pyrid-4-yl-ethynyl)]benzoic acid (PEBA). These rigid, rodlike molecules comprising the same complementary moieties for hydrogen bond formation are comparable in shape and size. For PVBA, the ethenylene moiety accounts for two-dimensional (2-D) chirality upon confinement to a surface; PEBA is linear and thus 2-D achiral. Molecular films were deposited on a Ag(111) surface by organic molecular beam epitaxy and characterized by scanning tunneling microscopy. At low temperatures (around 150 K), both species form irregular networks of flat lying molecules linked via their endgroups in a diffusion-limited aggregation process. In the absence of kinetic limitations (adsorption or annealing at room temperature), hydrogen-bonded supramolecular assemblies form which are markedly different. With PVBA, enantiomorphic twin chains in two mirror-symmetric species running along a high-symmetry direction of the substrate lattice form by diastereoselective self-assembly of one enantiomer. The chirality signature is strictly correlated between neighboring twin chains. Enantiopure one-dimensional (1-D) supramolecular nanogratings with tunable periodicity evolve at intermediate coverages, reflecting chiral resolution in micrometer domains. In contrast, PEBA assembles in 2-D hydrogen-bonded islands, which are enantiomorphic because of the orientation of the supramolecular arrangements along low-symmetry directions of the substrate. Thus, for PVBA, chiral molecules form 1-D enantiomorphic supramolecular structures because of mesoscopic resolution of a 2-D chiral species, whereas with PEBA, the packing of an achiral species causes 2-D enantiomorphic arrangements. Model simulations of supramolecular ordering provide a deeper understanding of the stability of these systems.

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“…[7] X-ray photoelectron diffraction studies (XPD) of ( M )- [7]H on the stepped Cu(332) surface also confirmed this assignment. [8] Tartaric acid ( R , S -, R , R -, S , S -& racemate) and succinic acid were purchased from Aldrich and Merck with purities better than 99%. STM images were acquired in constant-current mode with the sample slowly cooled to 50 K. Molecular modeling calculations (MMC) were performed using …”

Section: Methodsmentioning

confidence: 99%

Expression and Amplification of Chirality in Two-Dimensional Molecular Crystals

Ernst¹

2008

Chimia

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Expression and amplification of chirality in two-dimensional molecular crystals Expression and amplification of chirality in two-dimensional molecular crystals Abstract Chirality can be bestowed onto achiral surfaces by adsorption of chiral molecules. This offers a good opportunity to study two-dimensional chiral crystallization phenomena, like lateral resolution of enantiomers or the transfer of handedness from single molecules into mesoscopic ensembles with high resolution by scanning probe microscopy. Induction of homochirality on surfaces via cooperatively amplified interactions in molecular monolayers is a new phenomenon of supramolecular surface chirality. Prochiral molecules will turn into either handedness upon adsorption, but doping with intrinsically chiral molecules breaks this symmetry and induces homochirality. A similar effect is induced by a small enantiomeric excess. The excess molecules provide the chiral bias that becomes amplified into single lattice chirality. Expression and Amplification of Chirality in Tw o-Dimensional Molecular CrystalsKarl-Heinz Ernst * Dedicated to Professor Jack D. Dunitz on the occasion of his 85 th birthdayAbstract: Chirality can be bestowed onto achiral surfaces by adsorption of chiral molecules. This offers a good opportunity to study two-dimensional chiral crystallization phenomena, like lateral resolution of enantiomers or the transfer of handedness from single molecules into mesoscopic ensembles with high resolution by scanning probe microscopy. Induction of homochirality on surfaces via cooperatively amplified interactions in molecular monolayers is a new phenomenon of supramolecular surface chirality. Prochiral molecules will turn into either handedness upon adsorption, but doping with intrinsically chiral molecules breaks this symmetry and induces homochirality. A similar effect is induced by a small enantiomeric excess. The excess molecules provide the chiral bias that becomes amplified into single lattice chirality.

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Orientation of chiral heptahelicene C30H18 on copper surfaces: An x-ray photoelectron diffraction study

Cited by 85 publications

References 33 publications

Molecular chirality at surfaces

Molecular chirality at surfaces

Stereochemical Effects in Supramolecular Self-Assembly at Surfaces: 1-D versus 2-D Enantiomorphic Ordering for PVBA and PEBA on Ag(111)

Expression and Amplification of Chirality in Two-Dimensional Molecular Crystals

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