Details of a Researcher - Einaga, Yasuaki

Papers - Einaga, Yasuaki

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Trans-Bis(2,2-diphenylethylamine-κN)bis(5,5-diphenylhydantoinato- κN³)copper(II) and its chloroform disolvate

Akitsu Takashiro, Einaga Yasuaki

Acta Crystallographica Section C: Crystal Structure Communications 61 ( 4 ) 2005.04

ISSN 0108-2701

The crystal structures of the title compounds, [Cu(C₁₅H ₁₁N₂-O₂)₂(C₁₄H ₁₅N)₂] and [Cu(C₁₅H₁₁N ₂O₂)₂(C₁₄H₁₅N) ₂]·2CHCl₃, respectively, have been determined. The red disolvate complex affords a square-planar CuN₄ coordination environment in which the Cu" atom lies on a centre of symmetry. The blue solvent-free complex affords a distorted square-pyramidal CuN₄O coordination environment and adjacent molecules form centrosymmetric dimers. A comparison of the different crystal structures focuses on the role of the solvent molecules in supramolecular assemblies of the copper(II) complexes. © 2005 International Union of Crystallography.

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Diaqua[(1R,2R)-N,N′-bis(3,5-dibromosalicylidene)-cyclohexane-1, 2-diamine-κ⁴O,N,N′,O′]manganese(III) perchlorate dihydrate

Akitsu Takashiro, Takeuchi Yuiri, Einaga Yasuaki

Acta Crystallographica Section E: Structure Reports Online 61 ( 4 ) 2005.04

ISSN 1600-5368

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(SP-4-1 )-Bis{aqua(1R,2R)-N,N′-bis(salicylidene)-cyclohexane-1, 2-diy[diamine-κ ⁴O,N,N′,O′]man-ganese(III)}-di-μ-cyano-κ ⁴N

Akitsu Takashiro, Takeuchi Yuiri, Einaga Yasuaki

Acta Crystallographica Section E: Structure Reports Online 61 ( 3 ) 2005.03

ISSN 1600-5368

The title compound. [Mn₂Ni(C₂₀H₂₀N ₂O₂)₂(CN)₄(H₂O) ₂], is the first chiral trinuclear complex having an Mn _III-NC-Ni_II-CN-Mn_III unit. A pair of the trans sites of [Ni(CN)₄]_2- links two Mn_III units. The Mn_III ion has a pseudo-octahedral coordination geometry with the four donor atoms of the tetradentate chiral Schiff base forming the equatorial plane, and with a bridging cyanide and an aqua ligand at the axial positions. © 2005 International Union of Crystallography Printed in Great Britain - all rights reserved.

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Self-cleaning particle coating with antireflection properties

Zhang Xin Tong, Sato Osamu, Taguchi Minori, Einaga Yasuaki, Murakami Taketoshi, Fujishima Akira

Chemistry of Materials 17 ( 3 ) 696 - 700 2005.02

ISSN 0897-4756

We report here a self-cleaning particle coating with antireflection (AR) properties. The coatings were prepared by (1) depositing SiO₂ single-layered particle coatings on polyelectrolyte-modified glass substrates through electrostatic attraction, (2) subsequently depositing another layer of TiO₂ nanoparticles through electrostatic attraction, and (3) removing the polymer by calcination at 500 °C. The AR effect of the coatings was studied with transmission spectra collected at normal incidence. The self-cleaning properties of the coatings were studied by the change of the water contact angle on octadodecyldimethylchlorosilane-modified coatings under 1.0 mW cm^-2 ultraviolet light. Both the AR and self-cleaning properties of the coatings were dependent on the concentration of colloidal TiO₂ solution used in the preparation. However, excellent surface wettability of the coatings for water was obtained, independent of the preparation conditions. The experimental findings are discussed in terms of the special structure of the particle coatings.

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The structure, photo-induced magnetization and correlation of the cyano-bridged two-dimensional hetero-bimetallic compounds

Li Guangming, Yan Pengfei, Sato Osamu, Einaga Yasuaki

Journal of Solid State Chemistry 178 ( 1 ) 36 - 40 2005.01

ISSN 0022-4596

Two new 3d-4f cyano-bridged hetero-bimetallic compounds with distinguished two-dimensional honeycomb network structure, {Ln(HP)₂(H ₂O)₃(μ-NC)₃Fe(CN)₃}_n, (Ln=Ce, Nd; HP=4-Hydroxypyridine) were synthesized and crystallographically characterized. A novel photo-induced magnetization phenomenon for {Nd(HP) ₂(H₂O)₃(μ-NC)₃Fe(CN) ₃}_n, was revealed and studied. Furthermore, the correlation between photo-induced magnetization and structure was proposed. © 2004 Elsevier Inc. All rights reserved.

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Use of boron-doped diamond electrode in ozone generation

Park Soo Gil, Kim Gyu Sik, Park Jong Eun, Einaga Yasuaki, Fujishima Akira

Journal of New Materials for Electrochemical Systems 8 ( 1 ) 65 - 68 2005.01

ISSN 1480-2422

Highly boron-doped diamond (BDD) electrode was used as anode for ozone generation system by electrolysis of acidic solution. We have succeeded to generate ozone by using this BDD electrode with high efficiency compared to traditional lead oxide (PbO₂) electrode. Ozone generation by using PbO₂ electrode was gradually decreased due to its structural degradation at continous operating. However, electrochemical and physical properties of the BDD electrode were kept its high stability even after long operation time (>3000 hours) in comparison with PbO₂ electrode. The stability of BDD electrode for long time operation was due to physical and chemical properties of diamond electrode. It was expected that the use of BDD electrode as an anode would make a positive contribution to the electrochemical ozone generation. © New. Mat. Electrochem. Systems.

Bis[(R)-3,5-dichloro-N-(1-phenylethyl)salicylideneaminato-k ²N,O]-copper(ll) and bis[(R)-3-ethoxy-N-(1-phenylethyl) salicylideneaminato-K²N,O]copper(ll)

Akitsu Takashiro, Einaga Yasuaki

Acta Crystallographica Section C: Crystal Structure Communications 60 ( 12 ) 2004.12

ISSN 0108-2701

The crystal structure of bis[(R)-3,5-dichloro-N-(1-phenyl-ethyl) salicylideneaminato- κ²N, O]-copper(II) and bis[(R)-3-ethoxy-N-(1-phenylethyl)salicylideneaminato-κ²N, O] copper(II) was investigated. The complexes adopt a compressed tetrahedral trans-[CuN₂O₂] coordination geometry. The complexes also differ from one another with respect to the 1-phenylethylamine moieties and the direction of the benzene rings. The structural change was found to be irreversible for both the complexes, though there are no intermolecular hydrogen bonds in the crystals.

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Electronic structures of B 2p and C 2p levels in boron-doped diamond films studied using soft x-ray absorption and emission spectroscopy

Nakamura Jin, Kabasawa Eiki, Yamada Nobuyoshi, Einaga Yasuaki, Saito Daisuke, Isshiki Hideo, Yugo Shigemi, Perera Rupert C C

Physical Review B - Condensed Matter and Materials Physics 70 ( 24 ) 1 - 6 2004.12

ISSN 1098-0121

X-ray absorption (XAS) and emission (XES) spectroscopy near B K and C K edges have been performed on metallic (∼0.1 at. % B, B-diamond) and semiconducting (∼0.03 at. % B and N, BN-diamond) doped diamond films. Both B K XAS and XES spectra show a metallic partial density of states (PDOS) with the Fermi energy of 185.3 eV, and there is no apparent boron-concentration dependence in contrast to the different electric property. In C K XAS spectrum of B-diamond, the impurity state ascribed to boron is clearly observed near the Fermi level. The Fermi energy is found to be almost same with the top of the valence band of nondoped diamond: E_V=283.9 eV. C K XAS of BN-diamond shows both the B-induced shallow level and N-induced deep and broad levels as the in-gap states, in which the shallow level is in good agreement with the activation energy (E_a=0.37 eV) estimated from the temperature dependence of the conductivity; namely, the change in C 2p PDOS of impurity-induced metallization is directly observed. The electric property of this diamond is ascribed mainly to the electronic structure of C 2p near the Fermi level. The observed XES spectra are compared with the discrete variational Xα (DVXα) cluster calculation. The DVXα result supports the strong hybridization between B 2p and C 2p observed in XAS and XES spectra, and suggests that the small amount of boron (≤0.1 at. %) in diamond occupies the substitutional site rather than interstitial site. © 2004 The American Physical Society.

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Reversible photo-switching of the magnetization of iron oxide nanoparticles at room temperature

Mikami Rie, Taguchi Minori, Yamada Koji, Suzuki Koji, Sato Osamu, Einaga Yasuaki

Angewandte Chemie - International Edition 43 ( 45 ) 6135 - 6139 2004.11

ISSN 1433-7851

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Racemic 3,5-dichloro-2-{[(1-phenylethyl)imino]methyl}phenol

Akitsu Takashiro, Takeuchi Yuiri, Einaga Yasuaki

Acta Crystallographica Section C: Crystal Structure Communications 60 ( 11 ) 2004.11

ISSN 0108-2701

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Bis[2-(quinolin-3-yliminomethyl)phenolato-κ ²N,O]-copper(II)

Akitsu Takashiro, Einaga Yasuaki

Acta Crystallographica Section E: Structure Reports Online 60 ( 11 ) 2004.11

ISSN 1600-5368

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Electroanalytical application of modified diamond electrodes

Ivandini Tribidasari A., Sato Rika, Makide Yoshihiro, Fujishima Akira, Einaga Yasuaki

Diamond and Related Materials 13 ( 11-12 ) 2003 - 2008 2004.11

ISSN 0925-9635

Metal-modified diamond electrodes were fabricated by using ion implantation method for electroanalytical applications. Nickel and copper ion were implanted at a different film of boron-doped diamond (BDD) with a dose of 5×10¹⁴ cm^-2 for each type of ion. The electrochemical behavior has been studied for glucose oxidation in alkaline media by using cyclic voltammetry and flow injection analysis. Those electrodes exhibited high catalytic activity and excellent electrochemical stability with low background current even after strong ultrasonication in the cleaning process. The results indicate that metal-implanted method could be a promising method for controlling the electrochemical properties of diamond electrodes. © 2004 Elsevier B.V. All rights reserved.

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Bis[(S)-N-(2-butyl)-3,5-dichlorosalicylideneaminato-k ²N,O]copper(II)

Akitsu Takashiro, Einaga Yasuaki

Acta Crystallographica Section E: Structure Reports Online 60 ( 11 ) 2004.11

ISSN 1600-5368

The title compound, [Cu(C₁₁H₁₂Cl₂NO) ₂], has a compressed tetrahedral trans-[CuN₂O ₂] coordination environment. The absolute configuration is found to be Δ(S,S) for the crystal examined. The Cu-N bond distances are 1.969 (4) and 1.971 (4) Å, while the Cu-O bond distances are 1.886 (3) and 1.892 (3) Å. The ligands, containing optically active (S)-2-butylamine moieties and electron-withdrawing Cl substituents, lead to an umbrella conformation of the overall molecule. On heating to 387 K, a structural phase transition is observed, probably involving a change in coordination geometry. © 2004 International Union of Crystallography Printed in Great Britain - all rights reserved.

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Bis[2-(phenethyliminomethyl)phenolato-κ²N,O]-copper(II)

Akitsu Takashiro, Einaga Yasuaki

Acta Crystallographica Section E: Structure Reports Online 60 ( 11 ) 2004.11

ISSN 1600-5368

The title compound, [Cu(C₁₅H₁₄NO)₂], adopts a stepped conformation and displays a square-planar trans-[CuN ₂O₂] coordination geometry. The asymmetric unit contains two independent half molecules and each Cu atom is located on a center of symmetry. For one molecule, the Cu-N and Cu-O bond distances are 2.013 (2) and 1.893 (2) Å, respectively, while for the other molecule, these distances are 2.008 (2) and 1.896 (2) A. The extended conformation of the phenethylimine pendant groups results in crystal packing formed by weakly aggregated planar molecules. © 2004 International Union of Crystallography Printed in Great Britain -all rights reserved.

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Electric-field-induced conductance switching in FeCo Prussian blue analogues

Sato Osamu, Kawakami Tomoko, Kimura Masanobu, Hishiya Shoko, Kubo Shoichi, Einaga Yasuaki

Journal of the American Chemical Society 126 ( 41 ) 13176 - 13177 2004.10

ISSN 0002-7863

FeCo Prussian blue analogues, which are known as typical molecule-based magnets, exhibited abrupt conductance switching by applying a high electric field as well as by varying the temperature. The current density versus electric field (J-E) curves of FeCo Prussian blue with Rb cations in interstitial sites shows so-called negative resistance effects at electric fields higher than the threshold voltage. This means that the FeCo Prussian blue analogues are multiproperty materials in the sense that their conducting, magnetic, and optical properties can be reversibly controlled by certain external stimuli. Copyright © 2004 American Chemical Society.

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Pt-implanted boron-doped diamond electrodes for electrochemical oxidation of hydrogen peroxide

Ivandini Tribidasari A., Sato Rika, Makide Yoshihiro, Fujishima Akira, Einaga Yasuaki

Chemistry Letters 33 ( 10 ) 1330 - 1331 2004.10

ISSN 0366-7022

Pt-modified diamond electrodes were fabricated for electroanalytical applications by implantation method with a dose of 5 × 10¹⁴ cm^-2. The electrochemical behavior has been studied for oxidation of hydrogen peroxide by using cyclic voltammetry in phosphate buffer solution. With very low background current in comparison to that of Pt metal electrode, the electrode exhibited higher signal to background ratio (≈3.8 times) as well as better electrochemical and physical stability.

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Visible light-induced magnetization change of the cyano-bridged 3d-4f heterobimetallic

Li Guangming, Sato Osamu, Akitsu Takashiro, Einaga Yasuaki

Journal of Solid State Chemistry 177 ( 10 ) 3835 - 3838 2004.10

ISSN 0022-4596

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Modified diamond electrodes for electrolysis and electroanalysis applications

Einaga Yasuaki, Sato Rika, Olivia Herlambang, Shin Dongchan, Ivandini T. A., Fujishima Akira

Electrochimica Acta 49 ( 22-23 SPEC. ISS. ) 3989 - 3995 2004.09

ISSN 0013-4686

The outstanding properties of diamond make it a very attractive material for use in many potential applications. In particular, the superior electrochemical properties of highly boron-doped conductive diamond films, prepared by the chemical vapor deposition (CVD) process, have received attention from electrochemists. This paper reports several diversified applications of boron-doped diamond electrodes; highly sensitive and interference-free microfiber electrodes with over-oxidized polypyrrole modification, integrated electrochemical detector for microchip capillary electrophoresis (CE), and smoothing treatments of micro-polycrystalline surface. Studies have been made of the electrochemical properties of each system and their application in electroanalysis is discussed. © 2004 Elsevier Ltd. All rights reserved.

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Formation of a stable thin sheet of Prussian blue in a clay-organic hybrid film

Umemura Yasushi, Einaga Yasuaki, Yamagishi Akihiko

Materials Letters 58 ( 20 ) 2472 - 2475 2004.08

ISSN 0167-577X

Hybrid films of Prussian blue (PB), clay nanosheets, and alkylammonium cations were prepared by a combined method of Langmuir-Blodgett and self-assembly techniques. The absorbance at 700 nm for the hybrid film increased quadratically up to the 20th layer, and over the 20th layer it increased linearly. This indicated that the hybrid layers were built up in a layer-by-layer way over the 20th layer. X-ray diffraction (XRD) patterns of the film showed that stable thin sheets of PB were formed in the film, and that the in-plane structure of the PB sheet was identical to that of polycrystalline PB. © 2002 Elsevier B.V. All rights reserved.

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Three-dimensional 3d-4f hetero-bimetallic coordination polymers through hydrogen bonds

Li Guangming, Akitsu Takashiro, Sato Osamu, Einaga Yasuaki

Journal of Coordination Chemistry 57 ( 10 ) 855 - 864 2004.07

ISSN 0095-8972

Four cyano-bridged 3d-4f hetero-bimetallic Ln(III)-Fe(III) assemblies, {[Ln(DMF)₄(H₂O)₃(μ-CN)Fe(CN)₅] · H₂O)_n (Ln = Ce (1), Nd (2), Sm (3) and Gd (4); DMF = N,N-dimethylformamide), have been synthesized. X-ray crystallographic analysis of both 3 and 4 reveals three-dimensional network structures resulting from hydrogen bonds in the crystals. With respect to the coordination number on Sm(III) atoms, 3 is different from previously reported structures. Structural comparison indicates that the differences in magnetic properties between 3 and 4 do not derive from structural factors. Mössbauer spectra at both 298 and 10 K reveal that the characteristic quadrupole splitting for low-spin Fe(III) ions (S = 1/2) remains unchanged, indicating that the spin state of Fe(III) ions in 1-4 is not affected by temperature. The magnetic anisotropy derived from the ground states of Ln(III) ions with odd 4fⁿ electrons (n = 1, 3, 5 and 7), ²F_5/2, ⁴I_9/2, ⁶H_5/2 and ⁸S_7/2 for Ce(III), Nd(III), Sm(III) and Gd(III), respectively, dominates the exchange interaction in the Ln(III)-NC-Fe(III) systems.

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