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267 results on '"Amsharov, Konstantin"'

6. Rational Synthesis of Fullerenes, Buckybowls, and Single-Walled Carbon Nanotubes by a Surface-Assisted Approach

Author

Amsharov, Konstantin, Abe, Akihiro, Series editor, Albertsson, Ann-Christine, Series editor, Coates, Geoffrey W, Series editor, Genzer, Jan, Series editor, Kobayashi, Shiro, Series editor, Lee, Kwang-Sup, Series editor, Leibler, Ludwik, Series editor, Long, Timothy E., Series editor, Möller, Martin, Series editor, Okay, Oguz, Series editor, Percec, Virgil, Series editor, Tang, Ben Zhong, Series editor, Terentjev, Eugene M., Series editor, Theato, Patrick, Series editor, Vicent, Maria J., Series editor, Voit, Brigitte, Series editor, Wiesner, Ulrich, Series editor, Zhang, Xi, Series editor, Müllen, Klaus, editor, and Feng, Xinliang, editor

Published
2017
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12. Two Rings Around One Ball: Stability and Charge Localization of [1 : 1] and [2 : 1] Complex Ions of [10]CPP and C 60/70 [ * ]

Author

Freiberger, Markus, primary, Minameyer, Martin B., additional, Solymosi, Iris, additional, Frühwald, Stefan, additional, Krug, Marcel, additional, Xu, Youzhi, additional, Hirsch, Andreas, additional, Clark, Timothy, additional, Guldi, Dirk M., additional, von Delius, Max, additional, Amsharov, Konstantin, additional, Görling, Andreas, additional, Pérez‐Ojeda, M. Eugenia, additional, and Drewello, Thomas, additional

Published
2023
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14. Synthesis and Characterization of 15N‐Labeled Poly(sulfur nitride) in Bulk and in Superconductor Composites.

Author

Kressler, Jörg, Radicke, Julian, Busse, Karsten, Amsharov, Konstantin, Golitsyn, Yury, Reichert, Detlef, Syrowatka, Frank, and Hasan, Nazmul

Subjects
YTTRIUM barium copper oxide, SUPERCONDUCTORS, NITRIDES, SULFUR, TIME-of-flight spectroscopy, NUCLEAR magnetic resonance
Abstract

15N‐labeled tetrasulfur tetranitride (S415N4) was synthesized by reacting S2Cl2 with 15NH3. The reaction was finalized with 14NH3. The successful labeling was confirmed by solution 15N nuclear magnetic resonance (NMR) spectroscopy. S415N4 was used for the synthesis of poly(sulfur nitride) S15Nx via the intermediate species of S2N2. It was a topochemical polymerization in the solid state. The isotope ratio in the labeled polymer was obtained by laser deposition ionization time‐of‐flight mass spectroscopy. Solid‐state 15N NMR spectroscopy of S15Nx indicates that at least three different chemical environments for 15N atoms are present in the crystals. Finally, SNx was polymerized in the presence of two other superconductors, MgB2 and yttrium barium copper oxide (YBCO), which demonstrates the capability of SNx for grain boundary engineering. [ABSTRACT FROM AUTHOR]

Published
2023
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18. Selecting the Reaction Path in On-Surface Synthesis through the Electron Chemical Potential in Graphene

Author

Kraus, Stefan, Herman, Alexander, Huttmann, Felix, Kramer, Christian, Amsharov, Konstantin, Tsukamoto, Shigeru, Wende, Heiko, Atodiresei, Nicolae, Michely, Thomas, Kraus, Stefan, Herman, Alexander, Huttmann, Felix, Kramer, Christian, Amsharov, Konstantin, Tsukamoto, Shigeru, Wende, Heiko, Atodiresei, Nicolae, and Michely, Thomas

Abstract

The organometallic on-surface synthesis of the eight-membered sp(2) carbon-based ring cyclooctatetraene (C8H8, Cot) with the neighboring rare-earth elements ytterbium and thulium yields fundamentally different products for the two lanthanides, when conducted on graphene (Gr) close to the charge neutrality point. Sandwich-molecular YbCot wires of more than 500 angstrom length being composed of an alternating sequence of Yb atoms and upright-standing Cot molecules result from the on-surface synthesis with Yb. In contrast, repulsively interacting TmCot dots consisting of a single Cot molecule and a single Tm atom result from the on-surface synthesis with Tm. While the YbCot wires are bound through van der Waals interactions to the substrate, the dots are chemisorbed to Gr via the Tm atoms being more electropositive compared to Yb atoms. When the electron chemical potential in Gr is substantially raised (n-doping) through backside doping from an intercalation layer, the reaction product in the synthesis with Tm can be tuned to TmCot sandwich-molecular wires rather than TmCot dots. By use of density functional theory, it is found that the reduced electronegativity of Gr upon n-doping weakens the binding as well as the charge transfer between the reaction intermediate TmCot dot and Gr. Thus, the assembly of the TmCot dots to long TmCot sandwich-molecular wires becomes energetically favorable. It is thereby demonstrated that the electron chemical potential in Gr can be used as a control parameter in an organometallic on-surface synthesis to tune the outcome of a reaction.

Published
2022

20. Two Rings Around One Ball: Stability and Charge Localization of [1: 1] and [2: 1] Complex Ions of [10]CPP and C60/70.

Author

Freiberger, Markus, Minameyer, Martin B., Solymosi, Iris, Frühwald, Stefan, Krug, Marcel, Youzhi Xu, Hirsch, Andreas, Clark, Timothy, Guldi, Dirk M., von Delius, Max, Amsharov, Konstantin, Görling, Andreas, Pérez-Ojeda, M. Eugenia, and Drewello, Thomas

Subjects
ELECTROSPRAY ionization mass spectrometry, COLLISION induced dissociation, COMPLEX ions, RADICAL cations, ISOTHERMAL titration calorimetry, RADICAL anions, MOLECULAR shapes
Abstract

We investigate the gas-phase chemistry of noncovalent complexes of [10]cycloparaphenylene ([10]CPP) with C60 and C70 by means of atmospheric pressure photoionization and electrospray ionization mass spectrometry. The literature-known [1: 1] complexes, namely [10]CPP⊃C60 and [10]CPP⊃C70, are observed as radical cations and anions. Their stability and charge distribution are studied using energy-resolved collision-induced dissociation (ER-CID). These measurements reveal that complexes with a C70 core exhibit a greater stability and, on the other hand, that the radical cations are more stable than the respective radical anions. Regarding the charge distribution, in anionic complexes charges are exclusively located on C60 or C70, while the charges reside on [10]CPP in the case of cationic complexes. [2: 1] complexes of the ([10]CPP2 ⊃C60/70)+ ⋅/- ⋅ type are observed for the first time as isolated solitary gas-phase species. Here, C60 -based [2: 1] complexes are less stable than the respective C70 analogues. By virtue of the high stability of cationic [1: 1] complexes, [2: 1] complexes show a strongly reduced stability of the radical cations. DFT analyses of the minimum geometries as well as molecular dynamics calculations support the experimental data. Furthermore, our novel gas-phase [2: 1] complexes are also found in 1,2-dichlorobenzene. Insights into the thermodynamic parameters of the binding process as well as the species distribution are derived from isothermal titration calorimetry (ITC) measurements. [ABSTRACT FROM AUTHOR]

Published
2023
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26. Comparative study of direct and graphite-mediated oxidation of large PAHs

Author

Weippert, Jürgen, Huber, Philipp, Hauns, Jakob, Narita, Akimitsu, Müllen, Klaus, Amsharov, Konstantin Y., Böttcher, Artur, Kappes, Manfred M., and Publica

Abstract

We have used a surface-science-based, ion-beam-soft-landing approach to study the heterogeneous oxidation of a series of large polycyclic aromatic hydrocarbons (PAHs)deposited onto highly oriented pyrolytic graphite (HOPG). The reactivities of well-defined thin films of hexabenzocoronene (C42H18), pentacene (C22H14), fullerene precursor (C60H30), and rubrene (C42H28) with effusive beams of oxygen atoms were compared to the reaction outcome upon depositing a monolayer of the same PAHs onto a preoxidized graphite surface. In both cases, sublimable oxidized derivatives of PAHs were observed using mass-resolved temperature programmed desorption (with compositions assigned using oxygen isotope labeling where necessary). For all PAHs investigated, the on-top oxidation of multilayers leads to epoxides. By contrast, the products of the oxidation of (sub)monolayers are seen to depend on the molecular structure of the PAH. While the flatly adsorbing planar PAHs react to form lactones and quinones, the highly nonplanar rubrene does not show analogous surface-mediated chemistry, instead forming epoxides exclusively. These observations when taken together with our previous study of coronene oxidation are of potential interest for sp2-nanocarbon-based oxidation catalysis. Furthermore, we have demonstrated a ultra high vacuum (UHV)-based route to sublimable oxides ranging in size up to C60H30O5, which may be useful for nanotechnological applications.

Published
2021

27. Domino dehydrative ��-extension : a facile path to extended perylenes and terrylenes

Author

Feofanov, Mikhail, Akhmetov, Vladimir, and Amsharov, Konstantin

Abstract

Towards nanographenes: Domino-DPEX (dehydrative ��-extension) is a new synthetic approach to extended nanographenes containing a perylene or terrylene core. The pronounced regioselctivity towards aldehyde groups in different positions makes DPEX an excellent tool for implementing pre-programmed multiple annulation of simple precursors of elusive nanographenes. This approach enables the formation of up to five C���C bonds in one-step in up to 94 % per C���C bond. Herein, we report a new method for synthesis of extended perylenes and terrylenes. The technique is based on the cascade dehydrative ��-extensions (DPEX) of aryl aldehydes, in which stepwise annulations activate previously ���dormant��� substituents. Two- and fourfold cyclizations of 3-aryl-biphenyl-2,2���-dicarbaldehydes offer a rapid path to unsymmetrical perylenes and elusive terrylene derivatives, respectively. DPEX of 3,3������-(phenanthrene-1,8-diyl)bis (([1,1���-biphenyl]-2,2���-dicarbaldehyde)) leads to the biradical structure, which proceeds in situ into oxidative electrocyclization at room temperature. The described domino process complements and expands DPEX approach to a large family of fused acenes and related PAHs.

Published
2021
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28. A Family of Superhelicenes: Easily Tunable, Chiral Nanographenes by Merging Helicity with Planar π Systems

Author

Reger, David, primary, Haines, Philipp, additional, Amsharov, Konstantin Y., additional, Schmidt, Julia A., additional, Ullrich, Tobias, additional, Bönisch, Simon, additional, Hampel, Frank, additional, Görling, Andreas, additional, Nelson, Jenny, additional, Jelfs, Kim E., additional, Guldi, Dirk M., additional, and Jux, Norbert, additional

Published
2021
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43. Carbon Origami via an Alumina-Assisted Cyclodehydrofluorination Strategy

Author

Steiner, Ann‐Kristin, Sharapa, Dmitry I., Troyanov, Sergey I., Nuss, Jürgen, and Amsharov, Konstantin

Subjects
aryl–aryl coupling, Technology, C−F bond activation, carbon origami, cyclodehydrofluorination, ddc:600, multihelical nanographenes
Abstract

The synthesis of pristine non‐planar nanographenes (NGs) via a cyclodehydrofluorination strategy is reported and the creation of highly strained systems via alumina‐assisted C−F bond activation is shown. Steric hindrance could execute an alternative coupling program leading to rare octagon formation offering access to elusive non‐classical NGs. The combination of two alternative ways of folding could lead to the formation of various 3D NG objects, resembling the Japanese art of origami. The power of the presented “origami” approach is proved by the assembly of 12 challenging nanographenes that are π‐isoelectronic to planar hexabenzocoronene but forced out of planarity.

Published
2020

44. Solid-state construction of zigzag periphery via intramolecular C–H insertion induced by alumina-mediated C–F activation.

Author

Feofanov, Mikhail, Förtsch, Andreas, Amsharov, Konstantin, and Akhmetov, Vladimir

Subjects
CARBON-based materials, ALUMINUM oxide
Abstract

Caryl–F bond activation has become an important and quickly developing method for construction of carbon-based materials. We report that alumina-mediated C–F bond activation (AmCFA) enables construction of PAHs with zigzag periphery. This method includes formal Csp3–H activation and opens an avenue for generation of carbon-based nanomagnets directly on technologically relevant surfaces. [ABSTRACT FROM AUTHOR]

Published
2021
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