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411.
412.
Shihomi Nakao Yuuki Muraoka Mitsuhiro Higashihata Daisuke Nakamura Yoshiki Nakata Tatsuo Okada 《Applied Physics A: Materials Science & Processing》2014,117(1):63-67
We have synthesized ZnO nanocrystals, such as nanowires, nanorods, and nanosheets, using a nanoparticle-assisted pulsed laser deposition (NAPLD) method. Recently, we achieved position-controlled growth of the ZnO nanocrystals by means of a ZnO buffer layer and laser irradiation without any catalyst. The periodic structure was formed on the ZnO buffer layer by multi-beam interference patterning, and then vertically aligned ZnO nanowalls, corresponding to the patterning, were grown on the buffer layer. It was found that the periodic ZnO nanowalls grew along the c-axis direction by X-ray diffraction measurement. The well-aligned ZnO nanowalls are expected to be utilized as building blocks for field emitters and UV LEDs. The proposed technique can be used as one of the effective methods to control the growth position of the ZnO nanocrystals because various structures can be easily fabricated by a laser writing and a spatial light modulator. 相似文献
413.
Shintaro Takahashi Kazuki Nakaya Dr. María Frutos Dr. Antoine Baceiredo Dr. Nathalie Saffon-Merceron Dr. Stéphane Massou Dr. Norio Nakata Dr. Daisuke Hashizume Prof. Vicenç Branchadell Dr. Tsuyoshi Kato 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):16071-16075
A novel N-hetero-RhI-metallacyclic silanone 2 has been synthesized. The silanone 2 , showing an extremely large dimerization energy (ΔG=+86.2 kcal mol−1), displays considerable stability and persists in solution up to 60 °C. Above 120 °C, an intramolecular Csp3−H insertion occurs slowly over a period of two weeks leading to the bicyclic silanol 5 . The exceptional stability of 2 , related to the unusual electronic and steric effects of RhI-substituent, should allow for a more profound study and understanding of these new species. Furthermore, the metallacyclic silanone 2 presents two reactive centers (Si=O and Rh), which can be involved depending upon the nature of reagents. Of particular interest, the reaction with H2 starts with the hydrogenation of RhI center leading to the corresponding RhIII-dihydride complex 7 and it undergoes a cis/trans-isomerization via a particular mechanism, demonstrating that addition-elimination processes can also happen for silanones just like for their carbon analogues! 相似文献
414.
Yoshiki Nakata Keiichi Murakawa Kenji Sonoda Kazuma Momoo Noriaki Miyanaga Takuya Hiromoto 《Applied Physics A: Materials Science & Processing》2013,112(1):191-196
We have studied material processing by using an interfering ultra-short pulse laser. In this process, an interference pattern is transferred to material surface, and a periodic structure can be generated in a single shot of laser irradiation. Here, it is well known that the period of the interference pattern can be controlled by correlation angle and wavelength. In addition, a composite, doubled in density or designed interference pattern can be formed by controlling the phase shift and variation of amplitude between the interfering laser beams. In this paper, basic patterns of interference are summarized in the case of four-beam correlation. 相似文献
415.
S. Nishihara S. Yamanaka K. Nakata Y. Kitagawa Y. Yonezawa M. Okumura H. Nakamura T. Takada K. Yamaguchi 《Polyhedron》2009,28(9-10):1628-1633
We investigated several phenalenyl cationic dimer systems using ab initio methods. First, we examine the through-space cation dimer. The B3LYP method fails to describe the correct dissociation as in the case of usual cation dimers. On the other hand, the resonating broken symmetry configuration interaction (Res-BS CI) method based on unrestricted Hartree–Fock solutions yields the correct potential surface and correct charge distributions. Furthermore, we investigated though-bond interactions of the phenalenyl cationic dimer via acetylene and ethylene bridges. The results are considerably different from those of the though-space case, implying that these bridging units play important roles to determine charge and spin distributions. Judging from these results, different bridges-or-stacks lead to different hole behaviors, indicating the possibility of various electronic functionalities of hole-doped phenalenyl compounds. In particular, the acetylene bridge is expected to enhance the conductivity of the hole-doped phenalenyl compounds. 相似文献
416.
Satoshi Ninomiya Kazuya Ichiki Hideaki Yamada Yoshihiko Nakata Toshio Seki Takaaki Aoki Jiro Matsuo 《Rapid communications in mass spectrometry : RCM》2009,23(20):3264-3268
In this study, we present molecular depth profiling of multilayer structures composed of organic semiconductor materials such as tris(8‐hydroxyquinoline)aluminum (Alq3) and 4,4′‐bis[N‐(1‐naphthyl)‐N‐phenylamino]biphenyl (NPD). Molecular ions produced from Alq3 and NPD were measured by linear‐type time‐of‐flight (TOF) mass spectrometry under 5.5 keV Ar700 ion bombardment. The organic multilayer films were analyzed and etched with large Ar cluster ion beams, and the interfaces between the organic layers were clearly distinguished. The effect of temperature on the diffusion of these materials was also investigated by the depth profiling analysis with Ar cluster ion beams. The thermal diffusion behavior was found to depend on the specific materials, and the diffusion of Alq3 molecules was observed to start at a lower temperature than that of NPD molecules. These results prove the great potential of large gas cluster ion beams for molecular depth profiling of organic multilayer samples. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
417.
An antitumor acetogenin, muconin, was synthesized through a coupling reaction of a THF-THP segment and a terminal butenolide. The key reactions include successive ether-ring formation reaction under acidic and basic conditions or one-pot double cyclization promoted by TBAF and stereoselective reduction of acyclic ketones adjacent to the 2,6-cis THP with Zn(BH4)2. 相似文献
418.
The dihydroxyisoleucine-, thiazoline- and dehydroamino acid-containing pentapeptide of the thiostrepton family of peptide antibiotics was synthesized, which featured the β-lactone opening by phenylselenylation, the vinylzinc addition to the chiral sulfinimine, the Wipf oxazoline-thiazoline conversion method and the oxidative syn-elimination of the phenylseleno group. 相似文献
419.
Development of massive multilevel molecular dynamics simulation program,platypus (PLATform for dYnamic protein unified simulation), for the elucidation of protein functions
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Yu Takano Kazuto Nakata Yasushige Yonezawa Haruki Nakamura 《Journal of computational chemistry》2016,37(12):1125-1132
A massively parallel program for quantum mechanical‐molecular mechanical (QM/MM) molecular dynamics simulation, called Platypus (PLATform for dYnamic Protein Unified Simulation), was developed to elucidate protein functions. The speedup and the parallelization ratio of Platypus in the QM and QM/MM calculations were assessed for a bacteriochlorophyll dimer in the photosynthetic reaction center (DIMER) on the K computer, a massively parallel computer achieving 10 PetaFLOPs with 705,024 cores. Platypus exhibited the increase in speedup up to 20,000 core processors at the HF/cc‐pVDZ and B3LYP/cc‐pVDZ, and up to 10,000 core processors by the CASCI(16,16)/6‐31G** calculations. We also performed excited QM/MM‐MD simulations on the chromophore of Sirius (SIRIUS) in water. Sirius is a pH‐insensitive and photo‐stable ultramarine fluorescent protein. Platypus accelerated on‐the‐fly excited‐state QM/MM‐MD simulations for SIRIUS in water, using over 4000 core processors. In addition, it also succeeded in 50‐ps (200,000‐step) on‐the‐fly excited‐state QM/MM‐MD simulations for the SIRIUS in water. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. 相似文献
420.
Dr. Thibault Troadec Dr. Tatsuya Wasano Romaric Lenk Dr. Antoine Baceiredo Dr. Nathalie Saffon-Merceron Dr. Daisuke Hashizume Dr. Yosuke Saito Dr. Norio Nakata Prof. Vicenç Branchadell Dr. Tsuyoshi Kato 《Angewandte Chemie (International ed. in English)》2017,56(24):6891-6895
An isolable donor-stabilized silavinylidene phosphorane was synthesized. This molecule, which can also be regarded as a new carbon(0) complex featuring a phosphine and a donor-stabilized silylene ligand, presents a central carbon atom with a remarkably high electron density (−1.82). Furthermore, the experimental electron-density study of this compound demonstrates the delocalization of the σ-lone pair at the central carbon atom toward the silicon center, a feature which is remarkably different from electronic situation of other bent-allene-type molecules. This result clearly demonstrates the powerful electron-donating ability of donor-stabilized silylene ligands, as well as their excellent electron-acceptor properties. 相似文献