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8 results on '"Perepichka, D.F."'

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

Author

Lipton-Duffin, J.A., Miwa, J.A., Kondratenko, M., Cicoira, F., Sumpter, B.G., Meunier, V., Perepichka, D.F., and Rosei, F.

Subjects
Epitaxy -- Observations, Oligomers -- Properties, Polymerization -- Observations, Anisotropy -- Measurement, Copper -- Properties, Thiophene -- Properties, Scanning microscopy -- Methods, Science and technology
Abstract

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 Ullman 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 doi/ 10.1073/pnas.1000726107

Published
2010

4. A combined study of mesomorphism, optical, and electronic properties of donor-acceptor columnar liquid crystals

Author

Eichhorn, S.H. (author), Shuai, C. (author), Ahmida, M. (author), Demenev, A. (author), Kayal, H. (author), Raad, F.S. (author), Kaafarani, B.R. (author), Patwardhan, S. (author), Grozema, F.C. (author), Siebbeles, L.D.A. (author), Taerum, T. (author), Perepichka, D.F. (author), Klenkler, R. (author), Eichhorn, S.H. (author), Shuai, C. (author), Ahmida, M. (author), Demenev, A. (author), Kayal, H. (author), Raad, F.S. (author), Kaafarani, B.R. (author), Patwardhan, S. (author), Grozema, F.C. (author), Siebbeles, L.D.A. (author), Taerum, T. (author), Perepichka, D.F. (author), and Klenkler, R. (author)

Abstract

Donor-acceptor structures have recently gained great popularity for the design of low band gap polymeric organic semiconductors. Presented here is a first systematic study of organic semiconductors based on columnar liquid crystals that consist of discotic and board-shaped donor-acceptor structures. The discotic benzotristhiophenetricarboxamide and hexaphenyldiquinoxalinophenazine derivatives form hexagonal columnar mesophases over wide temperature ranges while the board-shaped tetraphenylquinoxalinophenanthrophenazine derivative displays rectangular and hexagonal columnar mesophases. All compounds are designed to preferentially conduct electrons and not holes because the central acceptor parts, which are the sole contributors to the unoccupied frontier orbitals, show strong intermolecular electronic interactions within columnar stacks whereas the donor parts at the periphery of the cores, the sole contributors to the occupied frontier orbitals, are too far apart to provide sufficient electronic interactions. The absence of hole conduction is confirmed by charge carrier mobility measurements based on time-resolved microwave conductivity and time-of-flight methods that reveal intrinsic electron mobility values of about 10-2 cm2 V–1 s–1. The board-shaped compound is also highly fluorescent not only in solution but also in its mesophases. Interstingly, the fluorescence quantum yield of its mesophases reversibly increases with decreasing temperature, which is reasoned with changes in molecular mobility and intracolumnar packing within columnar stacks., DelftChemTech, Applied Sciences

Published
2011
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8. Surface-Confined Macrocyclization via Dynamic Covalent Chemistry

Author

Emanuele Orgiu, Martin Kalbac, Boping Zhou, Chaoying Fu, Silvia Orlandi, Lea Assies, Jiří Mikšátko, Luca Muccioli, Dmitrii F. Perepichka, Xiaobin Zeng, Vladimír Vrkoslav, Petr Kovaříček, Fu C., Miksatko J., Assies L., Vrkoslav V., Orlandi S., Kalbac M., Kovaricek P., Zeng X., Zhou B., Muccioli L., Perepichka D.F., and Orgiu E.

Subjects
Surface (mathematics), Nanostructure, Materials science, General Engineering, General Physics and Astronomy, Dynamic covalent chemistry, Nanotechnology, 02 engineering and technology, on-surface synthesi, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, law.invention, Molecular dynamics, molecular dynamics simulation, law, scanning tunneling microscopy, General Materials Science, Density functional theory, dynamic covalent chemistry, Scanning tunneling microscope, 0210 nano-technology, macrocycle, density functional theory
Abstract

Surface-confined synthesis is a promising approach to build complex molecular nanostructures including macrocycles. However, despite the recent advances in on-surface macrocyclization under ultrahigh vacuum, selective synthesis of monodisperse and multicomponent macrocycles remains a challenge. Here, we report on an on-surface formation of [6 + 6] Schiff-base macrocycles via dynamic covalent chemistry. The macrocycles form two-dimensional crystalline domains on the micrometer scale, enabled by dynamic conversion of open-chain oligomers into well-defined ∼3.0 nm hexagonal macrocycles. We further show that by tailoring the length of the alkyl substituents, it is possible to control which of three possible products - oligomers, macrocycles, or polymers - will form at the surface. In situ scanning tunneling microscopy imaging combined with density functional theory calculations and molecular dynamics simulations unravel the synergistic effect of surface confinement and solvent in leading to preferential on-surface macrocyclization.

Published
2020

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