Molecular structure and chiral separation in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math>-sexithiophene ultrathin films on Au(111): Low-energy electron diffraction and scanning tunneling microscopy

Kiel, Mario; Duncker, Klaus; Hagendorf, Christian; Widdra, W.

doi:10.1103/physrevb.75.195439

Cited by 57 publications

(71 citation statements)

References 36 publications

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“…The mostly upright orientation is somewhat surprising for thiophene-derived units. Flat or slightly tilted orientations, enabling aromatic-metal interactions, have been consistently observed for oligothiophenes on Ag (23), Au (24,25), and Cu(110) (26,27). The upright orientation for dehalogenated EDOT is stabilized by two C-Cu bonds, as well as by strong Cu-S interactions and weak van der Waals contacts with the adjacent molecules in the stack.…”

Section: Resultsmentioning

confidence: 84%

Step-by-step growth of epitaxially aligned polythiophene by surface-confined reaction

Lipton‐Duffin

Miwa

Kondratenko

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

117

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One of the great challenges in surface chemistry is to assemble aromatic building blocks into ordered structures that are mechanically robust and electronically interlinked-i.e., are held together by covalent bonds. We demonstrate the surface-confined growth of ordered arrays of poly(3,4-ethylenedioxythiophene) (PEDOT) chains, by using the substrate (the 110 facet of copper) simultaneously as template and catalyst for polymerization. Copper acts as promoter for the Ullmann coupling reaction, whereas the inherent anisotropy of the fcc 110 facet confines growth to a single dimension. High resolution scanning tunneling microscopy performed under ultrahigh vacuum conditions allows us to simultaneously image PEDOT oligomers and the copper lattice with atomic resolution. Density functional theory calculations confirm an unexpected adsorption geometry of the PEDOToligomers, which stand on the sulfur atom of the thiophene ring rather than lying flat. This polymerization approach can be extended to many other halogen-terminated molecules to produce epitaxially aligned conjugated polymers. Such systems might be of central importance to develop future electronic and optoelectronic devices with high quality active materials, besides representing model systems for basic science investigations.metal-catalyzed coupling reaction | molecular wires | cis-polythiophene | scanning probe microscopy | polymerization mechanism T he tunability and diversity of the structural and electronic properties of π-conjugated organic polymers have spurred a wide interest in these materials as wires and semiconductors for future electronic devices (1, 2), although significant optimization is required for real breakthrough performance. Conventional organic synthesis can create conjugated polymers of practically any length and structure (3), yet their controlled positioning and ordering on a surface remains nontrivial. This supramolecular ordering ultimately controls properties such as the charge mobility and recombination, which are critical for any application, including nanoelectronics and light harvesting. The approach presented here proposes a way to precisely control the long-range order in conducting polymers by performing synthesis of these materials, in an epitaxial way, directly on crystalline substrates. Although electrochemical polymerization on conducting surfaces has long been used to prepare films of conjugated polymers such as polythiophene (4), the techniques for preparation and characterization of aligned arrays of polymers have only recently been developed. Promising results were obtained by using UV irradiation (5) or scanning probe microscope tip pulsing (6) to form polydiacetylenes and surface-catalyzed coupling to form polyphenylene (7). However, these polymers are not good conductors due to a very large bond length alternation in their conjugated acetylene structures. (8). Conductive ordered polythiophene wires have been prepared by pulsed electrooxidative polymerization of substituted thiophenes (9, 10). The symmetry of the...

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Section: Resultsmentioning

confidence: 84%

Step-by-step growth of epitaxially aligned polythiophene by surface-confined reaction

Lipton‐Duffin

Miwa

Kondratenko

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

117

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“…Heating the sample to 430 K has the same effect [10]. Whereas helium diffraction experiments on several alkanethiol striped phases [11] and STM investigations of azobenzene molecules on Au(1 1 1) [12] revealed an unperturbed reconstructed surface underneath the self-assembled monolayer, some adsorbed species, e.g., C 60 molecules [13], oxygen [14], hexa-peri-hexabenzocoronene [15] and a-sexithiophene [16] influence the reconstruction. Deposition of atomic sulfur completely lifts the reconstruction, with the 4.5% Au atoms released during deconstruction agglomerating at step edges [17,18].…”

Section: Introductionmentioning

confidence: 91%

Modified herringbone reconstruction on Au(111) induced by self-assembled Azure A islands

et al. 2008

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“…The first two will be of particular interest here, as they show opposed properties in some important characteristics. The n-thiophene molecules are chiral and exhibit interesting chiral phenomena in thin layers but not in the bulk [51].…”

Section: Rod-like Conjugated Moleculesmentioning

confidence: 99%

Nucleation and growth of thin films of rod-like conjugated molecules

Hlawacek

Teichert

2013

J. Phys.: Condens. Matter

107

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Abstract. Thin films formed from small molecules rapidly gain importance in different technological fields. To explain their growth, methods developed for zero-dimensional atoms as the film forming particles are applied. However, in organic thin film growth the dimensionality of the building blocks comes into play. Using the special case of the model molecule para-Sexiphenyl, we will emphasize the challenges that arise from the anisotropic and one-dimensional nature of building blocks. Differences or common features with other rodlike molecules will be discussed. The typical morphologies encountered for this group of molecules and the relevant growth modes will be investigated. Special attention is given to the transition between flat lying and upright orientation of the building blocks during nucleation. We will further discuss methods to control the molecular orientation and describe the involved diffusion processes qualitatively and quantitatively.

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Molecular structure and chiral separation inα-sexithiophene ultrathin films on Au(111): Low-energy electron diffraction and scanning tunneling microscopy

Cited by 57 publications

References 36 publications

Step-by-step growth of epitaxially aligned polythiophene by surface-confined reaction

Step-by-step growth of epitaxially aligned polythiophene by surface-confined reaction

Modified herringbone reconstruction on Au(111) induced by self-assembled Azure A islands

Nucleation and growth of thin films of rod-like conjugated molecules

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