The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Yukihiro Yoshida - One of the best experts on this subject based on the ideXlab platform.
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conducting Coronene cation radical salt containing magnetic metal ions
Inorganic Chemistry, 2019Co-Authors: Yukihiro Yoshida, Gunzi Saito, Mitsuhiko Maesato, Hiroshi KitagawaAbstract:Coronene is the smallest homologue of benzene and is the smallest fragment of graphene among 6-fold symmetric polycyclic aromatic hydrocarbons. In this study, we obtained the first Coronene cation ...
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Coronene-based charge-transfer complexes
Journal of Physics: Condensed Matter, 2016Co-Authors: Yukihiro Yoshida, Yoshihide Kumagai, Motohiro Mizuno, Mitsuhiko Maesato, Kazuhide Isomura, Hideo Kishida, Gunzi SaitoAbstract:: Recent developments in the arena of charge-transfer complexes composed of the D 6h-symmetric polycyclic aromatic hydrocarbon, Coronene, are highlighted with emphasis on the structural and physical properties of these complexes. Because of the dual electron-donating and -accepting abilities of Coronene, this group involves structurally-defined four cation salts and three anion salts. The Jahn-Teller distortions and in-plane motion of Coronene molecules in the solids, both of which are closely associated with the high symmetry of Coronene molecules, and syntheses of clathrate-type complexes are also presented.
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conducting π columns of highly symmetric Coronene the smallest fragment of graphene
Chemistry: A European Journal, 2016Co-Authors: Yukihiro Yoshida, Yoshihide Kumagai, Motohiro Mizuno, Kazuhide Isomura, Hideo Kishida, Hideki Yamochi, Yoshiaki Nakano, Masafumi Sakata, Takashi Koretsune, Mitsuhiko MaesatoAbstract:Coronene, which is the smallest D6h-symmetric polycyclic aromatic hydrocarbon, attracts particular attention as a basic component of electronic materials because it is the smallest fragment of graphene. However, carrier generation by physical methods, such as photo- or electric field-effect, has barely been studied, primarily because of the poor π-conduction pathway in pristine Coronene solid. In this work we have developed unprecedented π-stacking columns of cationic Coronene molecules by electrochemical hole-doping with polyoxometallate dianions. The face-to-face π–π interactions as well as the partially charged state lead to electrical conductivity at room temperature of up to 3 S cm−1, which is more than 10 orders of magnitude higher than that of pristine Coronene solid. Additionally, the robust π–π interactions strongly suppress the in-plane rotation of the Coronene molecules, which has allowed the first direct observation of the static Jahn–Teller distortion of cationic Coronene molecules.
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structure property relationship of supramolecular rotators of Coronene in charge transfer solids
Crystal Growth & Design, 2015Co-Authors: Yukihiro Yoshida, Yoshihide Kumagai, Motohiro Mizuno, Gunzi SaitoAbstract:Single crystals of charge-transfer (CT) complexes composed of the polyaromatic hydrocarbon, Coronene, as an electron donor (D) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) analogues as electron acceptor (A) were obtained. Elucidation of crystal structures of CT complexes enables a systematic investigation of dynamic properties of Coronene molecules lying in different types of crystalline environments. Solid-state 2H NMR spectra of CT complexes formed with deuterated Coronene confirmed the in-plane 6-fold flipping motion of the Coronene molecules. The dihedral angle between adjacent Coronene and TCNQ analogue within the DA-type alternating π-column is closely correlated with the dynamic properties, such as rotational rate and activation energy. Side-by-side intermolecular hydrogen-bonding also seems to have an effect in ways that lead to the suppressed rotation. These findings would provide an initial step toward the selection, design, and engineering of counter components of supramolecular rotators in the ...
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isotropic three dimensional molecular conductor based on the Coronene radical cation
European Journal of Inorganic Chemistry, 2014Co-Authors: Yukihiro Yoshida, Yoshihide Kumagai, Motohiro Mizuno, Mitsuhiko Maesato, Kazuhide Isomura, Hideo Kishida, Masanari Izumi, Yoshihiro Kubozono, Akihiro Otsuka, Hideki YamochiAbstract:In this study, we obtained the first cation radical solid of a highly symmetric (D6h) polyaromatic hydrocarbon, Coronene, by electrooxidation. The (Coronene)3Mo6Cl14 salt, which is formed with an Oh-symmetric molybdenum cluster unit Mo6Cl142–, has an isotropic cubic structure with Pmm symmetry. The presence of two orientations for the Coronene molecules related by an in-plane 90° rotation (merohedral disorder) allows for fourfold symmetry along the direction. The disorder has dynamic features because 2H NMR spectroscopic studies revealed that the Coronene molecules undergo an in-plane flipping motion. The observation of two motional sites with significantly different rotational rates (300 Hz and 5 MHz at 103 K) in an approximate 2:1 ratio appears to be consistent with the splitting of a Raman-active A1g mode, confirming a random charge-disproportionated state instead of a uniform partially-charged state. The slower- and faster-rotating species are assigned to charge-rich and charge-poor Coronenes, respectively, with respect to C–H···Cl hydrogen bonds with neighboring Mo6Cl142– cluster units. The electrical conductivity of the salt is rather high but is well-described by a three-dimensional (3D) variable-range hopping mechanism, which is possibly associated with the random charge disproportionation. These results provide a significant step forward in developing an isotropic 3D π-conducting system composed of planar π-conjugated molecules.
Max P Bernstein - One of the best experts on this subject based on the ideXlab platform.
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side group addition to the polycyclic aromatic hydrocarbon Coronene by proton irradiation in cosmic ice analogs
The Astrophysical Journal, 2003Co-Authors: Max P Bernstein, M H Moore, Jamie E Elsila, Scott A Sandford, L J Allamandola, Richard N ZareAbstract:Ices at ∼15 K consisting of the polycyclic aromatic hydrocarbon Coronene (C24H12) condensed either with H2O, CO2, or CO in the ratio of 1 : 100 or greater have been subjected to MeV proton bombardment from a Van de Graaff generator. The resulting reaction products have been examined by infrared transmissionreflection-transmission spectroscopy and by microprobe laser-desorption laser-ionization mass spectrometry. Just as in the case of UV photolysis, oxygen atoms are added to Coronene, yielding, in the case of H2O ices, the addition of one or more alcohol ( i OH) and ketone (1CuO) side chains to the Coronene scaffolding. There are, however, significant differences between the products formed by proton irradiation and the products formed by UV photolysis of Coronene containing CO and CO2 ices. The formation of a Coronene carboxylic acid ( i COOH) by proton irradiation is facile in solid CO but not in CO2, the reverse of what was previously observed for UV photolysis under otherwise identical conditions. This work presents evidence that cosmicray irradiation of interstellar or cometary ices should have contributed to the formation of aromatics bearing ketone and carboxylic acid functional groups in primitive meteorites and interplanetary dust particles. Subject headings: astrobiology — astrochemistry — comets: general — cosmic rays — ISM: molecules — molecular processes
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side group addition to the polycyclic aromatic hydrocarbon Coronene by ultraviolet photolysis in cosmic ice analogs
The Astrophysical Journal, 2002Co-Authors: Max P Bernstein, Jamie E Elsila, Scott A Sandford, L J Allamandola, Jason P Dworkin, Richard N ZareAbstract:Ultraviolet photolysis of various Coronene-ice mixtures at low temperature and pressure caused the addition of amino (”NH2), methyl (”CH3), methoxy (”OCH3), cyano/isocyano (”CN, ”NC), and acid (”COOH) functional groups to the polycyclic aromatic hydrocarbon (PAH) Coronene (C24H12), in addition to previously reported alcohol (”OH) and ketone (>C»O) formation. This work represents the first experimental evidence that ice photochemistry may have contributed to the aromatics bearing carbon and nitrogen containing side groups that are detected in primitive meteorites and interplanetary dust particles. Furthermore, these results suggest that a wide range of modified PAHs should be expected in interstellar ices and materials that predated solar system formation. The implications of these results for interstellar and meteoritic chemistry are discussed. Subject headings: astrobiology — astrochemistry — ISM: molecules — meteors, meteoroids — molecular processes — ultraviolet: ISM
L J Allamandola - One of the best experts on this subject based on the ideXlab platform.
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side group addition to the polycyclic aromatic hydrocarbon Coronene by proton irradiation in cosmic ice analogs
The Astrophysical Journal, 2003Co-Authors: Max P Bernstein, M H Moore, Jamie E Elsila, Scott A Sandford, L J Allamandola, Richard N ZareAbstract:Ices at ∼15 K consisting of the polycyclic aromatic hydrocarbon Coronene (C24H12) condensed either with H2O, CO2, or CO in the ratio of 1 : 100 or greater have been subjected to MeV proton bombardment from a Van de Graaff generator. The resulting reaction products have been examined by infrared transmissionreflection-transmission spectroscopy and by microprobe laser-desorption laser-ionization mass spectrometry. Just as in the case of UV photolysis, oxygen atoms are added to Coronene, yielding, in the case of H2O ices, the addition of one or more alcohol ( i OH) and ketone (1CuO) side chains to the Coronene scaffolding. There are, however, significant differences between the products formed by proton irradiation and the products formed by UV photolysis of Coronene containing CO and CO2 ices. The formation of a Coronene carboxylic acid ( i COOH) by proton irradiation is facile in solid CO but not in CO2, the reverse of what was previously observed for UV photolysis under otherwise identical conditions. This work presents evidence that cosmicray irradiation of interstellar or cometary ices should have contributed to the formation of aromatics bearing ketone and carboxylic acid functional groups in primitive meteorites and interplanetary dust particles. Subject headings: astrobiology — astrochemistry — comets: general — cosmic rays — ISM: molecules — molecular processes
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side group addition to the polycyclic aromatic hydrocarbon Coronene by ultraviolet photolysis in cosmic ice analogs
The Astrophysical Journal, 2002Co-Authors: Max P Bernstein, Jamie E Elsila, Scott A Sandford, L J Allamandola, Jason P Dworkin, Richard N ZareAbstract:Ultraviolet photolysis of various Coronene-ice mixtures at low temperature and pressure caused the addition of amino (”NH2), methyl (”CH3), methoxy (”OCH3), cyano/isocyano (”CN, ”NC), and acid (”COOH) functional groups to the polycyclic aromatic hydrocarbon (PAH) Coronene (C24H12), in addition to previously reported alcohol (”OH) and ketone (>C»O) formation. This work represents the first experimental evidence that ice photochemistry may have contributed to the aromatics bearing carbon and nitrogen containing side groups that are detected in primitive meteorites and interplanetary dust particles. Furthermore, these results suggest that a wide range of modified PAHs should be expected in interstellar ices and materials that predated solar system formation. The implications of these results for interstellar and meteoritic chemistry are discussed. Subject headings: astrobiology — astrochemistry — ISM: molecules — meteors, meteoroids — molecular processes — ultraviolet: ISM
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infrared spectroscopy of matrix isolated polycyclic aromatic hydrocarbon cations 2 the members of the thermodynamically most favorable series through Coronene
The Journal of Physical Chemistry, 1995Co-Authors: D M Hudgins, L J AllamandolaAbstract:Gaseous, ionized polycyclic aromatic hydrocarbons (PAHs) are thought to be responsible for a very common family of interstellar infrared emission bands. Here the near- and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to Coronene:phenanthrene, pyrene, benzo[e]pyrene, benzo[ghi]perylene, and Coronene, are presented to test this hypothesis. For those molecules that have been studied previously (pyrene, pyrene-d10, and Coronene), band positions and relative intensities are in agreement. In all of these cases we report additional features. Absolute integrated absorbance values are given for the phenanthrene, perdeuteriophenanthrene, pyrene, benzo[ghi]perylene, and Coronene cations. With the exception of Coronene, the cation bands corresponding to the CC modes are typically 2-5 times more intense than those of the CH out-of-plane bending vibrations. For the cations, the CC stretching and CH in-plane bending modes give rise to bands that are an order of magnitude stronger than those of the neutral species, and the CH out-of-plane bends produce bands that are 5-20 times weaker than those of the neutral species. This behavior is similar to that found in most other PAH cations studied to date. The astronomical implications of these PAH cation spectra are also discussed.
Hisanori Shinohara - One of the best experts on this subject based on the ideXlab platform.
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ultrafast charge transfer and relaxation dynamics in polymer encapsulating single walled carbon nanotubes polythiophene and Coronene polymer
Journal of Physical Chemistry C, 2018Co-Authors: Arao Nakamura, Yasumitsu Miyata, Kenichi Yamanaka, Kenshi Miyaura, Hong En Lim, Kazunari Matsuda, Boanerges Thendie, Taketo Kochi, Susumu Okada, Hisanori ShinoharaAbstract:We investigate the photophysical properties of polymer-encapsulating single-walled carbon nanotubes (SWNTs) using absorption spectroscopy, photoconductivity spectroscopy, and femtosecond pump–probe spectroscopy. In a polythiophene (PT)-encapsulating SWNT film, one or two PT layers are encapsulated within SWNTs, depending on the tube diameter. For single encapsulated PT layers, the photoconductivity action spectrum shows a large photocurrent signal corresponding to absorption bands associated with PT exciton and continuum states, indicating charge transfer between the PT and the small-diameter SWNT. Pump–probe measurements show that electron transfer to the SWNT occurs in 0.53 ps and electrons then recombine with holes remaining in the PT in 11 ps. In a Coronene-polymer-encapsulating SWNT film, weak absorption bands at 1.7 and 3.4 eV are observed in addition to the SWNT spectrum. Band calculations allow these to be assigned to optical transitions between the electronic states originating from the Coronene ...
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dimerization initiated preferential formation of Coronene based graphene nanoribbons in carbon nanotubes
Journal of Physical Chemistry C, 2012Co-Authors: Miho Fujihara, Yasumitsu Miyata, Ryo Kitaura, Yoshifumi Nishimura, Cristopher Camacho, Stephan Irle, Yoko Iizumi, Toshiya Okazaki, Hisanori ShinoharaAbstract:We have investigated the growth mechanism of Coronene-derived graphene nanoribbons (GNRs) using two different precursors: Coronene and a dimer form of Coronene, so-called dicoronylene (C48H20). For both of the precursors, the formation of nanoribbon-like materials inside carbon nanotubes (CNTs) was confirmed by transmission electron microscope observations. Experimental and theoretical Raman analysis reveals that the samples also encapsulated dicoronylene and linearly condensed other Coronene oligomers, which can be regarded as analogues to GNRs. Interestingly, it was found that the present doping condition of Coronene yields dicoronylene prior to encapsulation due to the thermal dimerization of Coronene. These results indicate that the dimerization before the encapsulation drives the preferential formation of the Coronene-based GNRs within CNTs.
Richard N Zare - One of the best experts on this subject based on the ideXlab platform.
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side group addition to the polycyclic aromatic hydrocarbon Coronene by proton irradiation in cosmic ice analogs
The Astrophysical Journal, 2003Co-Authors: Max P Bernstein, M H Moore, Jamie E Elsila, Scott A Sandford, L J Allamandola, Richard N ZareAbstract:Ices at ∼15 K consisting of the polycyclic aromatic hydrocarbon Coronene (C24H12) condensed either with H2O, CO2, or CO in the ratio of 1 : 100 or greater have been subjected to MeV proton bombardment from a Van de Graaff generator. The resulting reaction products have been examined by infrared transmissionreflection-transmission spectroscopy and by microprobe laser-desorption laser-ionization mass spectrometry. Just as in the case of UV photolysis, oxygen atoms are added to Coronene, yielding, in the case of H2O ices, the addition of one or more alcohol ( i OH) and ketone (1CuO) side chains to the Coronene scaffolding. There are, however, significant differences between the products formed by proton irradiation and the products formed by UV photolysis of Coronene containing CO and CO2 ices. The formation of a Coronene carboxylic acid ( i COOH) by proton irradiation is facile in solid CO but not in CO2, the reverse of what was previously observed for UV photolysis under otherwise identical conditions. This work presents evidence that cosmicray irradiation of interstellar or cometary ices should have contributed to the formation of aromatics bearing ketone and carboxylic acid functional groups in primitive meteorites and interplanetary dust particles. Subject headings: astrobiology — astrochemistry — comets: general — cosmic rays — ISM: molecules — molecular processes
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side group addition to the polycyclic aromatic hydrocarbon Coronene by ultraviolet photolysis in cosmic ice analogs
The Astrophysical Journal, 2002Co-Authors: Max P Bernstein, Jamie E Elsila, Scott A Sandford, L J Allamandola, Jason P Dworkin, Richard N ZareAbstract:Ultraviolet photolysis of various Coronene-ice mixtures at low temperature and pressure caused the addition of amino (”NH2), methyl (”CH3), methoxy (”OCH3), cyano/isocyano (”CN, ”NC), and acid (”COOH) functional groups to the polycyclic aromatic hydrocarbon (PAH) Coronene (C24H12), in addition to previously reported alcohol (”OH) and ketone (>C»O) formation. This work represents the first experimental evidence that ice photochemistry may have contributed to the aromatics bearing carbon and nitrogen containing side groups that are detected in primitive meteorites and interplanetary dust particles. Furthermore, these results suggest that a wide range of modified PAHs should be expected in interstellar ices and materials that predated solar system formation. The implications of these results for interstellar and meteoritic chemistry are discussed. Subject headings: astrobiology — astrochemistry — ISM: molecules — meteors, meteoroids — molecular processes — ultraviolet: ISM
