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61.
Photochromic performance of diarylethene single crystals was controlled by crystal engineering using non-covalent aromatic-aromatic interactions as the directional intermolecular force. A diarylethene derivative with two pentafluorophenyl groups, 1,2-bis(2-methyl-5-pentafluorophenyl-3-thienyl)perfluorocyclopentene (1a), formed stoichiometric co-crystals with benzene (Bz) and naphthalene (Np) by aryl-perfluoroaryl interactions. Face-to-face pi-stacking interactions between the pentafluorophenyl groups of 1a and the aromatic molecules are responsible for 2:1 and 1:1 stoichiometric compositions in 1a/Bz and 1a/Np co-crystals, respectively. The diarylethene underwent thermally stable and photoreversible photochromic reactions in a homo-crystal of 1a and co-crystals 1a/Bz and 1a/Np. The absorption spectra of the photogenerated closed-ring isomers varied depending on the conformation of the diarylethene molecules packed in the crystals. The diarylethene 1a also formed 1:1 stoichiometric co-crystals with different kinds of diarylethenes, 1,2-bis(2-ethyl-5-phenyl-3-thienyl)perfluorocyclopentene (2a) and 1,2-bis[2-methyl-5-(1-naphthyl)-3-thienyl]perfluorocyclopentene (3a). Both co-crystals 1a/2a and 1a/3a showed photochromism. Although 1a, 2a, and 3a underwent efficient photocyclization reactions in their homo-crystals, highly selective photocyclization reactions of 2a or 3a were observed in the co-crystals. The selective reactions were confirmed by HPLC and X-ray crystallography. Excited energy transfers from 1a to 2a and from 1a to 3a are considered to occur and cause the selective reactions. 相似文献
62.
63.
Yoshitaka Yoda Yasuhiko Imai Hisao Kobayashi Syunji Goto Kunikazu Takeshita Makoto Seto 《Hyperfine Interactions》2012,206(1-3):83-86
An Upgrade of the nuclear resonant scattering beamline, BL09XU in SPring-8 has been conducted. A liquid nitrogen cooled high-heat load monochromator was installed and a 2nd experimental hutch was constructed. The instruments installed in the hutch allow for a variety of sample conditions. Newly developed high-resolution monochromators with better stability including the back scattering geometry monochromator have opened up the easy access to more isotopes and more precise measurements. 相似文献
64.
65.
Dr. Yohei Hattori Tatsuya Maejima Yumi Sawae Jun-ichiro Kitai Prof. Masakazu Morimoto Dr. Ryojun Toyoda Prof. Hiroshi Nishihara Prof. Satoshi Yokojima Dr. Shinichiro Nakamura Prof. Kingo Uchida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11441-11450
The cyclization reaction of diarylethenes having an azulene ring occurs only via higher excited states. Novel diarylethenes having an azulene ring with a strong donor or acceptor were synthesized and examined in these reactions. A derivative having an electron-donating 1,3-benzodithiol-2-ylidenemethyl group at the 1-position of the azulene ring showed photochromism, whereas neither a derivative having a π-conjugated electron-donating group at the 3-position of the azulene ring nor derivatives having a π-conjugated electron-withdrawing group at the 1- or 3-position of the azulene ring showed any photochromism. The photoreactivities of these compounds were explained by calculating forces and bond orders on the excited states using density functional theory (DFT) and time-dependent (TD)-DFT. 相似文献
66.
67.
Goto J. Oshima M. Sugawara M. Yamaguchi Y. Bi C. Bamba S. Morimoto T. 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(3):1707-1714
Charged particle activation analysis (CPAA) is a rapid method with high accuracy which can analyze multi-elements simultaneously. Since multiple γ-ray detection method is expected to improve the detection efficiency and the signal-to-noise ratio, we study what design of the γ-ray detector array is the most suitable for CPAA. We take up four design candidates and investigated the responses by the radiation simulation code Geant 4. From the results, we have deduced the best design with 5 germanium detectors in close geometry. By inspecting the sensitivity in CPAA, the method is proved to be useful and applicable to 116 nuclides.
相似文献68.
69.
Takeshi Kodama Shingo AokiSeiho Kikuchi Tomoki MatsuoYoshimitsu Tachi Keisuke NishikawaYoshiki Morimoto 《Tetrahedron letters》2013
The first concise total synthesis of C2 symmetric (+)-ekeberin D4 (1) that exhibits antiplasmodial activity has been achieved in total nine steps and 27% yield from the known diol 4. The efficient synthetic method features the regio- and diastereoselective epoxidation of 4 and convergent coupling between half fragments 2 and 3 by taking into account the C2 symmetric property. 相似文献
70.
Dr. Jun‐ichi Ito Kohei Fujii Prof. Dr. Hisao Nishiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(2):601-605
NCN‐pincer Ru‐complexes containing bis(oxazolinyl)phenyl ligands serve as suitable catalysts in the direct conjugate additions of α,β‐unsaturated carbonyl compounds, including ketones, esters, and amides, as well as vinylphosphonates, giving various β‐alkynyl carbonyl and phosphonate compounds. A bis(oxazolinyl)phenyl (phebox)–Ru complex also catalyzes the asymmetric conjugate addition of an alkyne with a β‐substituted, α,β‐unsaturated ketone to produce a chiral β‐alkynyl ketone. 相似文献