Asato Eiji

写真a

Title

Professor

Researcher Number(JSPS Kakenhi)

10222580

Current Affiliation Organization 【 display / non-display

  • Duty   University of the Ryukyus   Faculty of Science   Chemistry, Biology and Marine Science   Professor  

Academic degree 【 display / non-display

  • Kyushu University -  Doctor of Science

External Career 【 display / non-display

  • 2010.06
     
     

    University of the Ryukyus, Faculty of Science, Department of Chemistry, Biology, and Marine Science, Analytical and Inorganic Chemistry, Professor  

Research Interests 【 display / non-display

  • Coordination Chemistry

Research Areas 【 display / non-display

  • Nanotechnology/Materials / Inorganic/coordination chemistry

Research Theme 【 display / non-display

  • Pharmaceutical and Material Chemistry of Group 15 Elements

  • Synthesis of Metal-Assembled Complexes with Redox-Active Ligands

  • Synthesis of Metal-Assembled Complexes with Large Macrocyclic Ligands

Published Papers 【 display / non-display

  • Crystal Structure of S<sub>8</sub> Molecule from Thiourea

    MIKURIYA Masahiro, TANIGUCHI Kazuki, KOYAMA Yoshiki, WATANABE Hiroaki, YOSHIOKA Daisuke, MITSUHASHI Ryoji, ASATO Eiji

    X-ray Structure Analysis Online ( 社団法人 日本分析化学会 )  36 ( 0 ) 1 - 2   2020 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    <p>Sulfur S<sub>8</sub> was isolated from a reaction solution of thiourea and bismuth nitrate in <i>N,N</i>-dimethylformamide. The crystal structure was determined by the single-crystal X-ray diffraction method at 90 K. It crystallizes in the orthorhombic space group <i>Fddd</i> with <i>a</i> = 10.3310(8)Å, <i>b</i> = 12.6786(10)Å, <i>c</i> = 24.3519(19)Å, <i>V</i> = 3189.7(4)Å<sup>3</sup>, <i>D</i><sub>x</sub> = 2.136 g/cm<sup>3</sup>, and <i>Z</i> = 6. The <i>R</i>1 [<i>I</i> > 2σ(<i>I</i>)] and <i>wR</i>2 (all data) values are 0.0220 and 0.0570, respectively, for all 1864 independent reflections. The S<sub>8</sub> molecule has a crown-shaped ring structure with the α-form.</p>

  • Synthesis and magnetic properties of a dinuclear manganese(II) complex with two manganese(II) ions of C-2-twisted octahedral geometry

    Hiroshi Sakiyama, Masatoshi Kato, Satoshi Sasaki, Moriya Tasaki, Eiji Asato, Masayuki Koikawa

    POLYHEDRON ( PERGAMON-ELSEVIER SCIENCE LTD )  111   32 - 37   2016.06 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    A dinuclar manganese(II) complex [Mn-2(sym-hcp)(2)](BPh4)(2).2acetone.2H(2)O (1) was synthesized with a new dinucleating ligand, 4-chloro-2,6-bis1(2-hydroxyethyl)methylaminomethyllphenol [H(sym-hcp)I, for the purpose of studying the magnetic properties. The single-crystal X-ray analysis revealed a bis-mu-phenolato-dimanganese(II) core structure containing two distorted octahedral manganese(II) ions of C-2 symmetry. The order of the coordination bond lengths is Mn-O(phenolato) &lt; Mn-O(hydroxy) &lt; Mn-N. Magnetic susceptibility data for 1 was fitted well with the parameters 2J = -0.93 cm(-1) and g = 2.03, indicating weak antiferromagnetic interaction. (C) 2016 Elsevier Ltd. All rights reserved.

  • Effects of La doping on structural, optical, electronic properties of Sr2Bi2O5 photocatalyst

    Yuki Obukuro, Shigenori Matsushima, Kenji Obata, Takuya Suzuki, Masao Arai, Eiji Asato, Yuji Okuyama, Naoki Matsunaga, Go Sakai

    JOURNAL OF ALLOYS AND COMPOUNDS ( ELSEVIER SCIENCE SA )  658   139 - 146   2016.02 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    Single-phase Sr2Bi2O5 was obtained by calcination of the heterobimetallic complex precursor Sr [Bi(DTPA)]center dot 9H(2)O (DTPA is diethylenetriaminepentaacetic acid) at 700 degrees C for 6 h. The effect of La doping on the crystal structure, surface area, morphology, surface chemical state, and absorption properties of Sr2Bi2O5 samples prepared from Sr[Bi(DTPA)]center dot 9H(2)O were investigated. No traces of an impurity phase were detected in samples with a lower La content (3 and 5 mol%), while impurity phases such as Sr2Bi2O5 and SrCO3 were observed in Sr2Bi2O5 samples with larger La contents of 8 and 10 mol%. The Brunauer-Emmett-Teller surface area of Sr2Bi2O5 increased slightly with the content of La. High-resolution transmission electron microscopy revealed clear crystalline planes for both undoped and La-doped Sr2Bi2O5 samples without amorphous phases. Meanwhile, X-ray photoelectron spectroscopy indicated that the valence states of constituent metals were Sr2+, Bi3+, and La3+. The solubility limit of La in the Sr2Bi2O5 crystal phase was determined from Raman scattering measurements. La atoms substituted Bi sites when the doping content was low, while both Bi and Sr sites were substituted with La when the content of La was high. The electronic structure of Sr2Bi2O5 could be modified by La doping, resulting in a red shift of the absorption edge with increasing La content. The band-gap narrowing of Sr2Bi2O5 with La-doping was reproduced in energy-band calculations. The photocatalytic activity of Sr2Bi2O5 under visible-light irradiation for the oxidation of isopropanol was enhanced by doping with La. (C) 2015 Elsevier B.V. All rights reserved.

  • Synthesis and Characterization of a Di-µ-oxalato Tetracopper(Ⅱ) Complex with Tetranucleating Macrocyclic Ligand

    Miyazato Yuji, Asato Eiji, Ohba Masaaki, Wada Tohru

    Bulletin of the Chemical Society of Japan ( 公益社団法人 日本化学会 )  89 ( 4 ) 430 - 436   2016 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    A tetracopper(II) complex containing two oxalate anions in the metal-based host cavity, [Cu<sub>4</sub>(L<sub>py</sub>)(&micro;-ox)<sub>2</sub>](PF<sub>6</sub>)<sub>2</sub>&middot;2(2-PrOH), where ox<sup>2&minus;</sup>: oxalato (C<sub>2</sub>O<sub>4</sub><sup>2&minus;</sup>), was prepared by reacting <b>H<sub>2</sub>L<sub>py</sub></b>, a phenol-based tetranucleating macrocyclic ligand with four pyridylmethyl pendant arms, Cu(ClO<sub>4</sub>)<sub>2</sub>&middot;6H<sub>2</sub>O, and sodium oxalate (1:4:2 stoichiometry, respectively) in methanol, followed by exchange of the counteranion with excess of NH<sub>4</sub>PF<sub>6</sub>. Single-crystal X-ray diffraction of <b>1</b> revealed that two {Cu(II)Cu(II)} units, bridged by a phenolato group of <b>L<sub>py</sub></b><sup>2&minus;</sup>, were connected by two oxalato anions, to construct a rectangular &ldquo;{CuCu}(&micro;-ox)<sub>2</sub>{CuCu}&rdquo; tetranuclear framework. This rectangular framework was maintained in DMF solution. The magnetic measurement of <b>1</b> in the 2&ndash;300 K range revealed antiferromagnetic behavior. The antiferromagnetic interaction in this complex occurs between the Cu(II) centers bridged by an oxalate (<i>J</i> = &minus;140 cm<sup>&minus;1</sup>).

  • Structural investigation of nickel(II) complexes with bidentate aminoether ligands in solution based on the electronic spectra

    Ryo Yamaguchi, Takashi Tokue, Yoshio Watanabe, Katsuya Tone, Yusuke Tamashiro, Eiji Asato, Hiroshi Sakiyama

    POLYHEDRON ( PERGAMON-ELSEVIER SCIENCE LTD )  96   44 - 50   2015.08 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    For the purpose of investigating molecular structures in solution based on electronic spectra, two mononuclear nickel(II) complexes, [Ni(moen)(2)(DMF)(2)](BPh4)(2) (1) and [Ni(thfn)(2)(DMF)(2)](BPh4)(2) (2), were newly prepared using bidentate aminoether ligands [moen = 2-methoxyethylamine; thfn = 2-tetrahydro-furfurylamine; DMF=N,N-dimethylformamide]. Judging from the molar conductance, the complexes are considered to exist as monomeric cations in DMF solution. The electronic spectra of the complexes were measured in DMF and the spectra were typical for an octahedral geometry for both complexes, showing three spin-allowed d-d transition bands. Using the Gaussian curve fitting method, the spin-allowed bands were found to show a 2:1, 1:2 and 1:2 splitting pattern from lower to higher energy, which corresponds to a tetragonally elongated geometry. That is, the axial ligand field is weaker than the equatorial ligand field, and the ether oxygen atoms are considered to be in trans-positions. In order to ascertain the structures in solution, conformational analysis was conducted based on density functional theory (DFT) computations. The DFT results provided detailed structures which are consistent with the spectroscopic results. (C) 2015 Elsevier Ltd. All rights reserved.

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