研究者データベース

加藤 優(カトウ マサル)
地球環境科学研究院 物質機能科学部門 分子材料化学分野
准教授

基本情報

所属

  • 地球環境科学研究院 物質機能科学部門 分子材料化学分野

職名

  • 准教授

学位

  • 博士(理学)(埼玉大学)

J-Global ID

研究活動情報

論文

  • Masaru Kato, Ai Araki, Yuki Hara, Satoshi Taguchi, Ichizo Yagi
    Electrochemistry 86 5 220 - 222 2018年08月 [査読有り][通常論文]
  • Masaru Kato, Shogo Nakagawa, Takehiko Tosha, Yoshitsugu Shiro, Yuya Masuda, Kou Nakata, Ichizo Yagi
    The Journal of Physical Chemistry Letters 9 5195 - 5200 American Chemical Society ({ACS}) 2018年08月 [査読有り][通常論文]
  • Masaru Kato, Kazuya Ogura, Shogo Nakagawa, Shoichi Tokuda, Kiyonori Takahashi, Takayoshi Nakamura, Ichizo Yagi
    ACS Omega 3 9052 - 9059 2018年08月 [査読有り][通常論文]
  • Masaru Kato, Marika Muto, Naohiro Matsubara, Yohei Uemura, Yuki Wakisaka, Tsubasa Yoneuchi, Daiju Matsumura, Tomoko Ishihara, Takashi Tokushima, Shin-ichiro Noro, Satoru Takakusagi, Kiyotaka Asakura, Ichizo Yagi
    ACS Applied Energy Materials 1 2358 - 2364 American Chemical Society ({ACS}) 2018年05月 [査読有り][通常論文]
  • 表面増強赤外吸収分光法による電極/溶液界面における反応計測
    八木一三, 加藤優, 中田耕, 中川省吾
    分光研究 67 2 41 - 56 2018年04月 [査読有り][通常論文]
  • Kato Masaru, Sato Hisako, Yagi Ichizo, Sugiura Miwa
    Electrochimica Acta 264 386 - 392 2018年 [査読有り][通常論文]
  • Tomoko Ishihara, Takashi Tokushima, Yuka Horikawa, Masaru Kato, Ichizo Yagi
    REVIEW OF SCIENTIFIC INSTRUMENTS 88 10 104101  2017年10月 [査読有り][通常論文]
     
    We developed a spectro-electrochemical cell for X-ray absorption and X-ray emission spectroscopy, which are element-specific methods to study local electronic structures in the soft X-ray region. In the usual electrochemical measurement setup, the electrode is placed in solution, and the surface/interface region of the electrode is not normally accessible by soft X-rays that have low penetration depth in liquids. To realize soft X-ray observation of electrochemical reactions, a 15-nm-thick Pt layer was deposited on a 150-nm-thick film window with an adhesive 3-nm-thick Ti layer for use as both the working electrode and the separator window between vacuum and a sample liquid under atmospheric pressure. The designed three-electrode electrochemical cell consists of a Pt film on a SiC window, a platinized Pt wire, and a commercial Ag vertical bar AgCl electrode as the working, counter, and reference electrodes, respectively. The functionality of the cell was tested by cyclic voltammetry and X-ray absorption and emission spectroscopy. As a demonstration, the electroplating of Pb on the Pt/SiC membrane window was measured by X-ray absorption and real-time monitoring of fluorescence intensity at the O 1s excitation. Published by AIP Publishing.
  • Masaru Kato, Manabu Okui, Satoshi Taguchi, Ichizo Yagi
    JOURNAL OF ELECTROANALYTICAL CHEMISTRY 800 46 - 53 2017年09月 [査読有り][通常論文]
     
    Nitrate anion is one of the main nitrogen-containing-pollutants in groundwater and can be removed" using denitrification systems including electrocatalytic systems. Herein we report on electrocatalytic nitrate reduction catalyzed on tin-modified single crystalline electrodes of palladium, platinum and palladium-platinum alloy in acidic and neutral media. We have prepared electrodes with the (111) surface or the (100) surface and modified their surface with tin. Cyclic voltammetry of the electrodes has revealed that the tin-modified alloy (trimetallic) electrodes show higher electrocatalytic activity than the tin-modified platinum or palladium (bimetallic) electrodes, and the catalytic reaction is more efficiently catalyzed on the (100) surface rather than the (111) surface. The tin-modified PdPt(100) electrode shows the highest catalytic activity in acidic media as well as in neutral media. X-ray photoelectron spectroscopy suggests that metallic tin forms on the (100) surface, but divalent tin species on the (111) surface, indicating that a surface alloy of tin may form on the (100) surface, resulting in enhancement of the electrocatalytic activity. Our findings suggest that design and preparation of ternary metallic electrodes with the (100) surface will pave the way to the development of practical systems on electrocatalytic denitrification. (C) 2017 Elsevier B.V. All rights reserved.
  • Masaru Kato, Takeshi Murotani, Ichizo Yagi
    CHEMISTRY LETTERS 45 10 1213 - 1215 2016年10月 [査読有り][通常論文]
     
    We report an Fe/Cu/N-doped carbon electrocatalyst for the oxygen reduction reaction to water. Pyrolysis of metal precursors supported on oxidized carbon black provides the electrocatalyst with high catalytic activity and selectivity. Detailed physical-chemical studies have revealed that the. copresence of iron and copper catalytic sites in carbon in a 1:1 mole ratio, which is the same as that of an enzyme of cytochrome c oxidase, might be the key to synthesize highly active and selective electrocatalysts.
  • Masaru Kato, Nobuhisa Oyaizu, Katsuaki Shimazu, Ichizo Yagi
    JOURNAL OF PHYSICAL CHEMISTRY C 120 29 15814 - 15822 2016年07月 [査読有り][通常論文]
     
    We report two-dimensional model systems to study the electrocatalytic activities of dinuclear copper complexes for various electrocatalytic reactions including the oxygen reduction reaction (ORR), where we can use electrochemical techniques as well as surface-sensitive techniques such as X-ray photoelectron spectroscopy and vibrational sum frequency generation spectroscopy. Heteroaromatic thiols, including four triazoles and a thiadiazole, are used as metal ligands as well as anchors to a polycrystalline gold electrode. The thiols are self-assembled on the polycrystalline gold electrode and then react with copper(II) ions to give monolayers of copper-based ORR catalysts on the surface. The dinuclear copper complexes of 1,2,4-triazole-3-thiol and 3-amino-1,2,4-triazole-5-thiol show ORR activity and pH-dependent catalytic behavior similar to that of counterparts supported on carbon black, suggesting that our two-dimensional systems can serve as model catalysts for carbon-supported molecular catalysts. We have also self-assembled dinuclear copper complexes with long alkyl or perfluoroalkyl chains on the surface and studied their orientation on the surface and oxygen transport.
  • Masaru Kato, Ken'ichi Kimijima, Mari Shibata, Hideo Notsu, Kazuya Ogino, Kiyoshi Inokuma, Narumi Ohta, Hiromitsu Uehara, Yohei Uemura, Nobuhisa Oyaizu, Tadashi Ohba, Satoru Takakusagi, Kiyotaka Asakura, Ichizo Yagi
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 17 14 8638 - 8641 2015年 [査読有り][通常論文]
     
    A dinuclear copper(II) complex of 3,5-diamino-1,2,4-triazole is one of the highly active copper-based catalysts for the oxygen reduction reaction (ORR) in basic solutions. Our in situ X-ray absorption near edge structure measurements revealed that deprotonation of the triazole ligand might cause coordination geometrical changes, resulting in the enhancement of the ORR activity.
  • Hisako Sato, Miwa Ochi, Masaru Kato, Kenji Tamura, Akihiko Yamagishi
    NEW JOURNAL OF CHEMISTRY 38 12 5715 - 5720 2014年12月 [査読有り][通常論文]
     
    Multi-layered hybrid films comprised of amphiphilic cationic iridium(III) complexes and the exfoliated layers of synthetic saponite were prepared by the modified Langmuir-Blodgett method. Two iridium(III) complexes, [Ir(dfppy)(2)(dc9bpy)](+) (dfppyH = 2-(4',6'-difluorophenyl)pyridine; dc9bpy = 4,4'-dinonyl-2,2'-bipyridine) and [Ir(dfppy)(2)(dc9bpy)(+) (piqH = 1-phenyisoquinoline), were used as blue (donor) and red emitters (acceptor), respectively. A non-luminescent hybrid layer of stearylammonium and synthetic saponite was deposited in a layer-by-layer manner to vary the distance between the donor and acceptor layers. Energy transfer was analysed according to the Forster-type mechanism with a focus on the dependence of its efficiency on the interlayer distance.
  • Masaru Kato, Jenny Z. Zhang, Nicholas Paul, Erwin Reisner
    CHEMICAL SOCIETY REVIEWS 43 18 6485 - 6497 2014年09月 [査読有り][通常論文]
     
    Photosynthesis is responsible for the sunlight-powered conversion of carbon dioxide and water into chemical energy in the form of carbohydrates and the release of O-2 as a by-product. Although many proteins are involved in photosynthesis, the fascinating machinery of Photosystem II (PSII) is at the heart of this process. This tutorial review describes an emerging technique named protein film photoelectrochemistry (PF-PEC), which allows for the light-dependent activity of PSII adsorbed onto an electrode surface to be studied. The technique is straightforward to use, does not require highly specialised and/or expensive equipment, is highly selective for the active fractions of the adsorbed enzyme, and requires a small amount of enzyme sample. The use of PF-PEC to study PSII can yield insights into its activity, stability, quantum yields, redox behaviour, and interfacial electron transfer pathways. It can also be used in PSII inhibition studies and chemical screening, which may prove useful in the development of biosensors. PSII PF-PEC cells also serve as proof-of-principle solar water oxidation systems; here, a comparison is made against PSII-inspired synthetic photocatalysts and materials for artificial photosynthesis.
  • Keiji Ohno, Tomoaki Sugaya, Masaru Kato, Noriko Matsumoto, Ryoko Fukano, Yasuyo Ogino, Sumio Kaizaki, Takashi Fujihara, Akira Nagasawa
    CRYSTAL GROWTH & DESIGN 14 8 3675 - 3679 2014年08月 [査読有り][通常論文]
     
    Hydrous crystals of [{Pd-II(bpy)}(2)(mu-x-tart)]. nH(2)O (bpy: 2,2'-bipyridine; tartH(2)(2-): tartrate; 1a: x = L, n = 6; 2a: x = D, n = 6; 3a: x = DL, n = 4; 4a: x = meso, n = 4) and anhydrous crystals of [{Pd-II(bpy)}(2)(mu-L-tart)] (1b) were isolated from aqueous and MeOH solutions, respectively. X-ray crystallography revealed the stacked structures of clamshell-like dinuclear units in 1a-3a and 1b, where intramolecular metal metal and pi-pi stacking interactions were observed. Right- and left-handed helically stacked columns were formed in the 1a and 2a crystals, respectively. The significant role of hydrogen bonding among lattice water molecules and tartrate is suggested because 1b exhibited a zigzag arrangement only through intermolecular metal-metal interactions. In 3a, L- and D-tart units stacked alternately in a zigzag arrangement with intermolecular pi-pi interactions. In 4a, dimeric aggregates of the twisted dinuclear units further formed a 2D sheet architecture.
  • Yi-Hsuan Lai, Masaru Kato, Dirk Mersch, Erwin Reisner
    FARADAY DISCUSSIONS 176 199 - 211 2014年 [査読有り][通常論文]
     
    This discussion describes a direct comparison of photoelectrochemical (PEC) water oxidation activity between a photosystem II (PSII)-functionalised photoanode and a synthetic nanocomposite photoanode. The semi-biological photoanode is composed of PSII from the thermophilic cyanobacterium Thermosynechococcus elongatus on a mesoporous indium tin oxide electrode (mesoITO| PSII). PSII embeds all of the required functionalities for light absorption, charge separation and water oxidation and ITO serves solely as the electron collector. The synthetic photoanode consists of a TiO2 and NiOx coated nanosheet-structured WO3 electrode (nanoWO(3)|TiO2|NiOx). The composite structure of the synthetic electrode allows mimicry of the functional key features in PSII: visible light is absorbed by WO3, TiO2 serves as a protection and charge separation layer and NiOx serves as the water oxidation electrocatalyst. MesoITO|PSII uses low energy red light, whereas nanoWO(3)|TiO2|NiOx requires high energy photons of blue-end visible and UV regions to oxidise water. The electrodes have a comparable onset potential at approximately 0.6 V vs. reversible hydrogen electrode (RHE). MesoITO|PSII reaches its saturation photocurrent at 0.84 V vs. RHE, whereas nanoWO(3)|TiO2|NiOx requires more than 1.34 V vs. RHE. This suggests that mesoITO|PSII suffers from fewer limitations from charge recombination and slow water oxidation catalysis than the synthetic electrode. MesoITO|PSII displays a higher 'per active' site activity, but is less photostable and displays a much lower photocurrent per geometrical surface area and incident photon to current conversion efficiency (IPCE) than nanoWO(3)|TiO2|NiOx.
  • Masaru Kato, Kei Unoura, Toshiyuki Takayanagi, Yasuhisa Ikeda, Takashi Fujihara, Akira Nagasawa
    INORGANIC CHEMISTRY 52 23 13375 - 13383 2013年12月 [査読有り][通常論文]
     
    Five metal complexes of 2-methylisothiazol-3(2H)-one (MIO), [Co-III(NH3)(5)(MIO)](3+), [Ru-II(NH3)(5)(MIO)](2+), [Ru-III(NH3)(5)(MIO)](3+), [(PtCl3)-Cl-II(MIO)](-), and trans-[(UO2)-O-VI(NO3)(2)(MIO)(2)], were synthesized, and their structures were determined by single-crystal X-ray crystallography. MIO is an ambidentate ligand and coordinates to metal centers through its oxygen atom in the cobalt(III), ruthenium(III), and uranium(VI) complexes and through its sulfur atom in the ruthenium(II) and platinum(III) complexes. This result suggests that MIO shows preferential behavior on its donating atoms. We also studied the electron-donor abilities of the oxygen and sulfur atoms of MIO. Various physical measurements on the conjugate acid of MIO and the MIO complexes allowed us to determine an acid dissociation constant (pK(a)) and donor number (DN) for the oxygen atom of MIO and Lever's electrochemical parameter (E-L) and a relative covalency parameter (k(L)) for the sulfur atom.
  • Masaru Kato, Tanai Cardona, A. William Rutherford, Erwin Reisner
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 135 29 10610 - 10613 2013年07月 [査読有り][通常論文]
     
    Photosystem II (PSII) offers a biological and sustainable route of photochemical water oxidation to O-2 and can provide protons and electrons for the generation of solar fuels, such as H-2. We present a rational strategy to electrostatically improve the orientation of PSII from a thermophilic cyanobacterium, Thermosynechococcus elongatus, on a nanostructured indium tin oxide (ITO) electrode and to covalently immobilize PSII on the electrode. The ITO electrode was modified with a self-assembled monolayer (SAM) of phosphonic acid ITO linkers with a dangling carboxylate moiety. The negatively charged carboxylate attracts the positive dipole on the electron acceptor side of PSII via Coulomb interactions. Covalent attachment of PSII in its electrostatically improved orientation to the SAM-modified ITO electrode was accomplished via an amide bond to further enhance red-light-driven, direct electron transfer and stability of the PSII hybrid photoelectrode.
  • Fezile Lakadamyali, Anna Reynal, Masaru Kato, James R. Durrant, Erwin Reisner
    CHEMISTRY-A EUROPEAN JOURNAL 18 48 15464 - 15475 2012年11月 [査読有り][通常論文]
     
    A visible-light driven H2 evolution system comprising of a RuII dye (RuP) and CoIII proton reduction catalysts (CoP) immobilised on TiO2 nanoparticles and mesoporous films is presented. The heterogeneous system evolves H2 efficiently during visible-light irradiation in a pH-neutral aqueous solution at 25 degrees C in the presence of a hole scavenger. Photodegradation of the self-assembled system occurs at the ligand framework of CoP, which can be readily repaired by addition of fresh ligand, resulting in turnover numbers above 300 molH2 (molCoP)-1 and above 200,000 molH2 (molTiO2 nanoparticles)-1 in water. Our studies support that a molecular Co species, rather than metallic Co or a Co-oxide precipitate, is responsible for H2 formation on TiO2. Electron transfer in this system was studied by transient absorption spectroscopy and time-correlated single photon counting techniques. Essentially quantitative electron injection takes place from RuP into TiO2 in approximately 180 ps. Thereby, upon dye regeneration by the sacrificial electron donor, a long-lived TiO2 conduction band electron is formed with a half-lifetime of approximately 0.8 s. Electron transfer from the TiO2 conduction band to the CoP catalysts occurs quantitatively on a 10 mu s timescale and is about a hundred times faster than charge-recombination with the oxidised RuP. This study provides a benchmark for future investigations in photocatalytic fuel generation with molecular catalysts integrated in semiconductors.
  • Masaru Kato, Tanai Cardona, A. William Rutherford, Erwin Reisner
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 134 20 8332 - 8335 2012年05月 [査読有り][通常論文]
     
    We report on a hybrid photoanode for water oxidation consisting of a cyanobacterial photosystem II (PSII) from Thermosynechococcus elongatus on a mesoporous indium-tin oxide (mesoITO) electrode. The three-dimensional metal oxide environment allows for high protein coverage (26 times an ideal monolayer coverage) and direct (mediator-free) electron transfer from PSII to mesoITO. The oxidation of water occurs with 1.6 +/- 0.3 mu A cm(-2) and a corresponding turnover frequency of approximately 0.18 +/- 0.04 (mol O-2) (mol PSII)(-1) s(-1) during red light irradiation. Mechanistic studies are consistent with interfacial electron transfer occurring not only from the terminal quinone Q(B), but also from the quinone Q(A) through an unnatural electron transfer pathway to the ITO surface.
  • Lakadamyali Fezile, Kato Masaru, Reisner Erwi
    Faraday Discussions 155 191 - 205 2012年 [査読有り][通常論文]
  • Fezile Lakadamyali, Masaru Kato, Nicoleta M. Muresan, Erwin Reisner
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 51 37 9381 - 9384 2012年 [査読有り][通常論文]
  • Masaru Kato, Shinjiro Izuka, Takashi Fujihara, Akira Nagasawa, Sigenao Kawai, Tomokazu Tanaka, Toshiyuki Takayanagi
    INORGANICA CHIMICA ACTA 370 1 304 - 310 2011年05月 [査読有り][通常論文]
     
    Structural and thermodynamic properties of biologically important metal-mugineic acid complexes have been studied from the theoretical side in order to understand the metal-chelating mechanism of phytosiderophore mugineic acid at an atomic level. Density-functional theory methods combined with the polarizable continuum model (PCM) have been employed to obtain free energies of complex formation and redox potentials for metal-mugineic acid complexes in solution. It has been found that the free energies of complex formation calculated at the B3LYP/PCM level of theory are in moderate agreement with available experimental results. The inclusion of explicit water molecules interacting with the carboxylic groups in deprotonated mugineic acid through strong hydrogen-bonds is found to further improve the calculated free energies of complex formation. (C) 2011 Elsevier B.V. All rights reserved.
  • Masaru Kato, Kazuo Hida, Takashi Fujihara, Akira Nagasawa
    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY 4 495 - 502 2011年02月 [査読有り][通常論文]
     
    A dinuclear copper(II) complex, [{Cu(II)Cl(O-mi)}(2)(mu-Cl)(2)] [mi = 2-methylisothiazol-3(2H)-one], has been synthesized and its molecular structure in the solid state determined by single-crystal X-ray analysis. The crystal consists of centrosymmetric dinuclear copper(II) units in which each copper(II) ion is doubly bridged by two chloride ions and has a slightly distorted square-planar geometry with a terminal chlorido ligand and a terminal mi ligand coordinated through the oxygen atom. The dinuclear units stack one on top of another to form a one-dimensional two-leg ladder structure. The magnetic susceptibility of the powder was measured in the temperature range 3.0-302 K. It was found that there are ferromagnetic interactions along the rung (in the same direction of the intramolecule; J(rung) = +5.03 +/- 0.03 cm(-1)) and the leg (in the same direction of the intermolecule; J(leg) = +1.96 +/- 0.02 cm(-1)) and an antiferromagnetic interaction along the diagonal (J(x) = -1.36 +/- 0.02 cm(-1)), the experimental data being fitted by the numerical calculation for a twelve-site ladder Hamiltonian. In addition, DFT calculations with the UB3LYP functional on the model complex [{Cu(II)Cl(O-mi)}(2)(mu-Cl)(2)] gave an intramolecular magnetic coupling constant J = +28.6 cm(-1) and indicated that the spin-density distribution on O in mi is less than that on the terminal Cl. We conclude that the O-donor ligand at the terminal position plays an essential role in the emerging intramolecular ferromagnetic interaction.
  • Koichiro Takao, Masaru Kato, Shinobu Takao, Akira Nagasawa, Gert Bernhard, Christoph Hennig, Yasuhisa Ikeda
    INORGANIC CHEMISTRY 49 5 2349 - 2359 2010年03月 [査読有り][通常論文]
     
    The U(VI) complex with a pentadentate Schiff base ligand (N,N'-disalicylidenediethylenetriaminate = saldien(2-)) was prepared as a starting material of a potentially stable U(V) complex without any possibility of U(V)O(2)(+)center dot center dot center dot U(V)O(2)(+) cation-cation interaction and was found in three different crystal phases. Two of them had the same composition of U(VI)O(2)(saldien)center dot DMSO in orthorhombic and monoclinic systems (DMSO = dimethyl sulfoxide, 1a and 1c, respectively). The DMSO molecule in both 1a and 1c does not show any coordination to U(VI)O(2)(saldien), but it is just present as a solvent in the crystal structures. The other isolated crystals consisted only of U(VI)O(2)(saldien) without incorporation of solvent molecules (1b, orthorhombic). A different conformation of the coordinated saldien(2-) in 1c from those in 1a and 1b was observed. The conformers exchange each other in a solution through a flipping motion of the phenyl rings. The pentagonal equatorial coordination of U(VI)O(2)(saldien) remains unchanged even in strongly Lewis-basic solvents, DMSO and N,N-dimethylformamide. Cyclic voltammetry of U(VI)O(2)(saldien) in DMSO showed a quasireversible redox reaction without any successive reactions. The electron stoichiometry determined by the UV-vis-NIR spectroelectrochemical technique is close to 1, indicating that the reduction product of U(VI)O(2)(saldien) is [U(V)O(2)(saldien)](-), which is stable in DMSO. The standard redox potential of [U(V)O(2)(saldien)](-)/U(VI)O(2)(saldien) in DMSO is -1.584 V vs Fc/Fc(+). This U(V) complex shows the characteristic absorption bands due to f-f transitions in its 5f(1) configuration and charge-transfer from the axial oxygen to U(5+).
  • Koichiro Takao, Masaru Kato, Shinobu Takao, Akira Nagasawa, Andreas C. Scheinost, Gert Bernhard, Christoph Hennig, Yasuhisa Ikeda
    ACTINIDES 2009 9 1 2010年 [査読有り][通常論文]
     
    A U(VI) complex with N,N'-disalicylidenediethylenetriaminate (saldien(2-)) was characterized by single crystal X-ray analysis and X-ray absorption fine structure (XAFS) spectroscopy, and its electrochemical behavior in a DMSO solution was studied. The obtained U(VI)-saldien(2-) complex recrystallized from DMSO was identified as orthorhombic (UO2)-O-VI(saldien)center dot DMSO. All coordination sites in the equatorial plane of UO22+ are occupied by coordinating O and N atoms of saldien(2-). Comparing a k(3)-weighted U L-III-edge EXAFS spectra of (UO2)-O-VI(saldien) in DMSO and DMF solutions with that in solid state, the molecular structure of (UO2)-O-VI(saldien) remains even in the solutions. Quasi-reversible redox waves of (UO2)-O-VI(saldien) were observed at E degrees = -1.582 +/- 0.005 V vs. Fc/Fc(+) (Delta E-p = 0.080-0.170 V at v = 0.010-0.500 V.s(-1)) in DMSO. UV-Vis-NIR absorption spectral change with the electrochemical reduction of (UO2)-O-VI(saldien) using the spectroelectrochemical technique shows isosbestic points clearly, indicating that the electrochemical reaction of (UO2)-O-VI(saldien) is only present. Using the absorbance change and the Nernstian equation, the electron stoichiometry in the reduction of (UO2)-O-VI(saldien) in DMSO was determined as 0.929. This quantity close to unity reveals a redox reaction, (UO2)-O-VI(saldien) + e(-) = [(UO2)-O-V(saldien)](-), i. e., (UO2)-O-VI(saldien) without unidentate ligands results in the stable U(V) complex, [(UO2)-O-V(saldien)](-), in DMSO. This U(V) species also shows the characteristic absorption bands of U(V) at 630, 700, 830, 1390, and 1890 nm as well as other U(V) complexes.
  • Masaru Kato, Toshiyuki Takayanagi, Takashi Fujihara, Akira Nagasawa
    INORGANICA CHIMICA ACTA 362 4 1199 - 1203 2009年03月 [査読有り][通常論文]
     
    Density functional theory (DFT) calculations have been performed for understanding the linkage isomerism of [Ru-II/III(NH3)(5)(dmso)](2+/3+) (dmso = dimethylsulfoxide) from a theoretical point of view. In particular, we focus on the interchange between O-bonded and S-bonded structures of the dmso ligand by oxidation/reduction. We have examined. five different exchange-correlation functionals (SVWN, BP86, mPWPW91, B3PW91, and B3LYP) in our DFT calculations and found that the relative stabilities of the O-bonded and S-bonded structures are largely dependent on the functional employed. From detailed analyses of atomic charge distributions, it has been found that the calculated atomic charges on the central metal ions are strongly correlated with the relative energies. We also studied the effect of solvation on the linkage isomerism using continuum solvation models. (C) 2008 Elsevier B. V. All rights reserved.
  • Masaru Kato, Miho Hayashi, Takashi Fujihara, Akira Nagasawa
    ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE 64 M684 - U621 2008年05月 [査読有り][通常論文]
     
    The absolute configuration of the octahedral fac-CoN3O3 title complex, [Co(C5H8NO2)(3)]center dot 3H(2)O, has been determined by single-crystal X- ray analysis. A three-dimensional network of hydrogen bonds is observed between the proline carboxylate groups and the three uncoordinated water molecules.
  • Masaru Kato, Takashi Fujihara, Daisaku Yano, Akira Nagasawa
    CRYSTENGCOMM 10 10 1460 - 1466 2008年 [査読有り][通常論文]
     
    Silver(I) coordination polymers formed by self-assembly of ambidentate ligands, 2-methylisothiazol-3(2H)-one (MI) and 5-chloro-2-methylisothiazol-3(2H)-one (CMI), have been characterized by single crystal X-ray analysis. The structure of the cation in [Ag-I(mu-O-mi)(2)] X (X = ClO4- (1); SbF6- (2)) is a one-dimensional chain while that in the nitrate salt, [Ag-2(I)(mu-O-mi)](NO3)(2) (3), is a three-dimensional network. A silver(I) complex with CMI, [Ag-I(mu-O-cmi)(2)] ClO4 (4), has also been synthesized and the cation has a one-dimensional chain structure. Although both MI and CMI have both O-and S-donor moieties, the oxygen atom dominantly coordinates to the silver(I) centre. The anion influence on the chain structure is attributed to the competition for the coordination ability between anions and MI, and the flexibility of the coordination sphere of d(10) silver(I) ion.
  • Masaru Kato, Takashi Fujihara, Daisaku Yano, Akira Nagasawa
    ACTA CRYSTALLOGRAPHICA SECTION E-CRYSTALLOGRAPHIC COMMUNICATIONS 63 O3097 - U2523 2007年07月 [査読有り][通常論文]
     
    The title molecule, C4H4ClNOS, contains an essentially planar five-membered ring. The C - C(= O) bond is slightly longer than expected. In the crystal structure, two-dimensional networks are formed through intermolecular C - Cl...O = C interactions [Cl...O = 2.9811 (19) angstrom].
  • Masaru Kato, Takashi Fujihara, Daisaku Yano, Akira Nagasawa
    ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE 63 O1839 - O1841 2007年04月 [査読有り][通常論文]
     
    The title compound, C4H6ClNOS center dot H2O, has a planar five-membered ring, with a delocalized positive charge. A three-dimensional network is formed through intermolecular O-H center dot center dot center dot O and O-H center dot center dot center dot Cl hydrogen bonds between 3-hydroxy-2-methylisothiazolium cations and water molecules, and between water molecules and chloride anions.
  • T Fujihara, M Kato, A Nagasawa
    ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE 61 O1439 - O1440 2005年05月 [査読有り][通常論文]
     
    The crystallographic analysis of the title compound, C12H28N+• ClO4-, (I), shows that intermolecular C-H••• O interactions stabilize the crystal structure. The compound is isomorphous with tetra-n-propylammonium iodide, whose structure has been described by Yoshida et al. [ Acta Cryst. ( 1994). C50, 1758-1760].

受賞

  • 2018年02月 Symposium on Nanomaterials for Environmental Purification and Energy Conversion (SNEPEC) Best Poster Award
     Incorporation of multinuclear copper active sites into nitrogen-doped carbon for electrochemical oxygen reduction 
    受賞者: 加藤 優
  • 2017年10月 International Symposium on Novel Energy Nanomaterials, Catalysts and Surfaces for Future Earth (NENCS) –Material Research, Characterization and Imaging by in situ/Operando XAFS and X-ray Techniques– NENCS Poster Award (General)
     Efficient Electrochemical Oxygen Reduction Catalyzed at Multinuclear Copper Active Sites Incorporated in Nitrogen-Doped Carbon Nanosheets 
    受賞者: 加藤 優
  • 2016年05月 公益社団法人日本表面科学会 第35回表面科学学術講演会講演奨励賞(新進研究者部門)
     カーボン担持銅二核錯体からなる酸素還元電極触媒のin situ XAFS観察 
    受賞者: 加藤 優


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