大久保 貴志 (オオクボ タカシ)

  • 理工学部 エネルギー物質学科 教授
Last Updated :2024/03/24

コミュニケーション情報 byコメンテータガイド

  • コメント

    金属錯体の合成、構造解析、電気伝導性などの機能性。

研究者情報

学位

  • 博士(理学)(東京都立大学大学院)

ホームページURL

J-Global ID

研究キーワード

  • 配位高分子   多核金属錯体   多孔性金属錯体   混合原子価配位高分子   誘電率   誘電測定   インピーダンス分光測定   電気伝導性   キャリア移動度   イオン伝導性   強誘電性   有機薄膜太陽電池   有機EL素子   電界効果トランジスタ   

現在の研究分野(キーワード)

    金属錯体の合成、構造解析、電気伝導性などの機能性。

研究分野

  • ナノテク・材料 / 無機・錯体化学
  • ナノテク・材料 / 機能物性化学

経歴

  • 2018年04月 - 現在  近畿大学理工学部教授
  • 2011年04月 - 2018年03月  近畿大学理工学部准教授
  • 2016年04月 - 2017年03月  カリフォルニア大学サンタバーバラ校客員研究員(兼任)
  • 2012年10月 - 2016年03月  科学技術振興機構「さきがけ」研究員(兼任)
  • 2007年10月 - 2011年03月  科学技術振興機構「さきがけ」研究員(兼任)
  • 2007年04月 - 2011年03月  近畿大学理工学部講師
  • 2000年03月 - 2007年03月  北陸先端科学技術大学院大学マテリアルサイエンス研究科助手
  • 2004年04月 - 2006年03月  日本学術振興会海外特別研究員(兼任)ノースウェスタン大学
  • 1999年04月 - 2000年02月  理化学研究所基礎科学特別研究員
  • 1996年04月 - 1999年03月  日本学術振興会特別研究員(DC1)

学歴

  • 1996年04月 - 1999年03月   東京都立大学大学院   理学研究科   化学専攻博士課程
  • 1994年04月 - 1996年03月   東京都立大学大学院   理学研究科   化学専攻修士課程
  • 1990年04月 - 1994年03月   東京都立大学   理学部   化学科
  • 1987年04月 - 1990年03月   栃木県立足利高等学校

研究活動情報

論文

  • Tomoki Nishiyama; Hirotaka Kitoh-Nishioka; Senku Tanaka; Masahiko Maekawa; Takayoshi Kuroda-Sowa; Masaki Yoshida; Masako Kato; Takashi Okubo
    Dalton Transactions 2024年 [査読有り]
     
    A photoconductive luminescence coordination polymer having an infinite two-dimensional (2D) structure containing copper(i) thiocyanate and a nitrogen-containing π-conjugated ligand.
  • Masahiko Maekawa; Terumasa Hayashi; Kunihisa Sugimoto; Takashi Okubo; T. Kuroda-Sowa
    Dalton Transactions 2023年 
    Novel four di-, tetranuclear and polymeric Cu(I)–bpprd/C2H4 complexes were anion-dependently prepared by the reactions of [Cu(C2H4)n]X (X = ClO4, NO3, BF4) with 2,4-bis(2-pyridyl)pyrimidine (bpprd) in Me2CO under C2H4 and they...
  • Naohiro Takahashi; Tomoki Nishiyama; Takuto Mibu; Yusaku Suenaga; Takashi Okubo; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    Inorganica Chimica Acta 541 121095 - 121095 2022年10月 [査読有り]
  • Tomoki Nishiyama; Naohiro Takahashi; Takuto Mibu; Masahiko Maekawa; Takayoshi Kuroda-Sowa; Yusaku Suenaga; Takashi Okubo
    Results in Chemistry 100470 - 100470 2022年08月 [査読有り]
  • Benjamin R. Luginbuhl; Seo-Jin Ko; Niva A. Ran; Huawei Hu; Shona M. Becwar; Akchheta Karki; Martin Seifrid; Takashi Okubo; Ming Wang; Harald W. Ade; Bradley F. Chmelka; Guillermo C. Bazan; G. N. Manjunatha Reddy; Thuc-Quyen Nguyen
    Solar RRL 6 8 2200135 - 2200135 2022年03月 [査読有り]
  • Masahiko Maekawa; Shoki Oda; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa
    RESULTS IN CHEMISTRY 4 2022年01月 [査読有り]
     
    The reactions of [Ir(H)(2)(PPh3)(2)(tptz)]PF6 (1) (tptz = 2,4,6-tris(2-pyridyl)-s-triazine) with {Cu(I), Ag(I)} salts under Ar afforded heterometallic trinuclear {Cu(I), Ag(I)}-Ir(III)-tptz hydride complexes [CuIr2(H)(4)(PPh3)(4)(tptz)(2)](PF6)(3)center dot 2Me(2)CO (2), [AgIr2(H)(4)(PPh3)(4)(tptz)(2)](PF6)(3)center dot 4Me(2)CO center dot H2O (3a) and [AgIr2(H)(4)(PPh3)(4)(tptz)(2)] (CF3SO3)(2)(PF6)center dot 4Me(2)CO (3b). We have demonstrated that Ir(III)-tptz complex 1 can serve as a potentially bridgeable Ir metalloligand. X-ray analyses showed that meaningful intramolecular pi-pi stacking interactions exist in {Cu(I), Ag(I)}-Ir(III)-tptz hydride complexes 2, 3a and 3b. These intramolecular pi-pi stacking interactions could be contributed to the structural stabilization of the distorted boat-shaped structure. H-1 and P-31 NMR analyses showed that the structures of {Cu(I), Ag(I)}-Ir(III)-tptz hydride complexes 2 and 3a are kept in solution. The significant H-1 NMR upfield shifts could be induced by the ring current effect from the phenyl groups of adjacent PPh(3 )ligands.
  • Masahiko Maekawa; Mafuyu Yabuta; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa
    Inorganica Chimica Acta 528 120628  Elsevier 2021年12月 [査読有り]
     
    The reactions of [Cu(MeCN)(4)]PF6 or [Cu(C2H4)(n)]ClO4 with 2,2' :6',4 ''-terpyridine (2,2' :6',4 ''-terpy) in MeOH under C2H4 afforded dinuclear Cu(I) complexes [Cu2(2,2' :6',4 ''-terpy)(2)](PF6)(2) (1) and [Cu-2(2,2':6',4 ''-terpy)(2)(ClO4)(2)] (2), respectively. In complex 1, the Cu(I) atom is coordinated by one N atom in the terminal site of 2,2' :6',4 ''-terpy and two N atoms in the chelate site of another 2,2':6',4 ''-terpy in the distorted trigonal-planar geometry. In complex 2, the Cu(I) atom is coordinated by one N atom in the terminal site of 2,2' :6',4 ''-terpy, two N atoms in the chelate site of another 2,2' :6',4 ''-terpy and one O atom of ClO4 anion in the distorted trigonal-pyramidal geometry. In both of complexes 1 and 2, two Cu(I) atoms are bridged by two 2,2' :6',4 ''-terpy in the head-to-tail fashion to form dinuclear Cu(I) complexes with a rectangular [Cu-2(2,2' :6',4 ''-terpy)(2)](2+) framework. In contrast, the reaction of [Cu(MeCN)(4)]PF6 with 2,2':6',4 ''-terpy in MeOH/CHCl3 under C2H4 afforded 1D Cu(I) coordination polymer {[Cu-2(2,2' :6',4 ''-terpy)(2)(C2H4)](PF6)(2)center dot CHCl3 center dot MeOH}(n) (3). One Cu(I) atom is coordinated by four N toms in the chelate sites of two 2,2':6',4 ''-terpy in the head-to-head fashion to form a distorted tetrahedral geometry. The other Cu(I) atom is coordinated by two N toms in the terminal sites of two 2,2' :6',4 ''-terpy in the tail-to-tail fashion and the C=C bond of C2H4 to form a trigonal-planar structure. These Cu (I) atoms are in turns bridged by 2,2' :6',4 ''-terpy in the two kinds of head-to-head and tail-to-tail fashions to form a unique 1D helical chain structure. When the complex 2 was dissolved in MeCN and the resultant red-brown solution was diffused with diethyl ether, Cu(I) coordination polymer {[Cu-2(2,2' :6',4 ''-terpy)(2)(MeCN)(2)] (ClO4)(2)}(n) (4) was collected. The Cu(I) atom is coordinated by two N atoms in the chelate site of 2,2' :6',4 ''-terpy, one N atom in the terminal site of another 2,2' :6',4 ''-terpy and one N atom of MeCN in the distorted tetrahedral geometry. The Cu(I) atoms are in turns bridged by 2,2' :6',4 ''-terpy in the head-to-tail fashion to form a unique 1D helical chain structure.
  • Takuto Mibu; Atsushi Iba; Yusaku Suenaga; Takashi Okubo; Masahiko Maekawa; Takayoshi Kuroda-Sowa; Kunihisa Sugimoto
    Inorganica Chimica Acta 527 120538 - 120538 2021年11月 [査読有り]
  • Kouichi Matsumoto; Kazuhiro Yamashita; Yuuki Sakoda; Hinata Ezoe; Yuki Tanaka; Tatsuya Okazaki; Misaki Ohkita; Senku Tanaka; Yuki Aoki; Daisuke Kiriya; Shigenori Kashimura; Masahiko Maekawa; Takayoshi Kuroda-Sowa; Takashi Okubo
    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY 2021 33 4620 - 4629 2021年09月 [査読有り]
     
    New star-shaped non-fullerene acceptors (5Z,5 ' Z,5 '' Z)-5,5 ',5 ''-((benzo[1,2-b : 3,4-b ' : 5,6-b '']trithiophene-2,5,8-triyltris(4-octylthiophene-5,2-diyl))tris(methaneylylidene))tris(3-octyl-2-thioxothiazolidin-4-one) (1: BTT-OT-ORD) and 2,2 ',2 ''-((5Z,5 ' Z,5 '' Z)-((benzo[1,2-b : 3,4-b ' : 5,6-b '']trithiophene-2,5,8-triyltris(4-octylthiophene-5,2-diyl))tris(methaneylylidene))tris(3-octyl-4-oxothiazolidine-5,2-diylidene))trimalononitrile (2: BTT-OT-OTZDM) with a benzotrithiophene core, alkyl-thiophen units, and acceptor units were designed and synthesized. The HOMO-LUMO levels of 1 and 2 were determined by photoemission spectroscopy and UV-Vis absorption spectroscopy. Binary blend and ternary blend bulk heterojunction (BHJ) organic solar cells with non-fullerene acceptors 1 and 2 were fabricated with the inverted device structures of glass/ITO/ZnO/active_layer/MoO3/Ag. Both binary blend BHJ solar cells with 1 and 2 show lower J(SC) and larger V-OC values than P3HT : PCBM solar cells. On the other hand, ternary blend BHJ organic solar cells, including 10 % of 1, exhibited a larger power conversion efficiency than P3HT : PCBM solar cells because the J(SC) value was largely improved.
  • Yusaku Suenaga; Takuto Mibu; Takashi Okubo; Masahiko Maekawa; Takayoshi Kuroda-Sowa; Kunihisa Sugimoto
    Dalton transactions (Cambridge, England : 2003) 50 28 9833 - 9841 2021年07月 [査読有り]
     
    The biscatechol, H4BP (4,4'-bis(3-tert-butyl-1,2-catechol)) that can directly connect two redox active catechol moieties was synthesized. Also, tris(2-pyridylmethyl)amine (tpa), bis(2-pyridylmethyl)(2-quinolylmethyl)amine (bpqa), (2-pyridylmethyl)bis(2-quinolyl methyl)amine (pbqa), and tris (2-quinolylmethyl)amine (tqa) were synthesized as terminal ligands of the tetracoordinated tripod. In total, five different dinuclear Co complexes were synthesized from H4BP with various terminal ligands as follows, [Co2(BP)(tpa)2](PF6)2 (1), [Co2(BP)(tpa)2](PF6)3 (2), [Co2(BP)(bpqa)2](PF6)2 (3), [Co2(BP)(pbqa)2](PF6)2 (4), and [Co2(BP)(tqa)2](PF6)2 (5). After a one-electron oxidation reaction of complex (1), complex (2), was isolated as a mixed valence state lsCoIII-[SQ-Cat]-lsCoIII, with an absorption intensity of about 1370 nm (intervalence charge transfer (IVCT) bands) in CH3CN solution. In addition, an investigation of the magnetic properties of the dinuclear Co complex (3) with SQUID showed that the χMT value gradually increased as the temperature increased from 280 to 380 K. Studies in the solid and solution states using electronic spectra, cyclic voltammetry and SQUID for the above complexes provide clear evidence for three different charge distributions: complexes (1) and (3) are CoIII-[Cat-Cat]-CoIII, complex (2) is CoIII-[Sq-Cat]-CoIII, complexes (4) and (5) are CoII-[Sq-Sq]-CoII. Of the five cobalt dinuclear complexes, only complex (3) shows evidence of the temperature dependence of the charge distribution, displaying a thermally induced valence tautomeric transition from the lsCoIII-[Cat-Cat]-lsCoIII to hsCoII-[Sq-Sq]-hsCoII in both solid and solution states. However, this valence tautomeric step is incomplete at 380 K, with the χMT value of hsCoII-[Sq-Sq]-hsCoII. This suggests that the steric hindrance of the quinolyl rings around the Co ion produces a coordination atmosphere that is weaker than that observed with pyridyl rings, which facilitates a change in the CoIII ions to CoII.
  • Kunihisa Sugimoto; Takashi Okubo; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    CRYSTAL GROWTH & DESIGN 21 7 4178 - 4183 2021年07月 [査読有り]
     
    Single crystals of an iron(II) spin crossover (SCO) complex containing an N2O Schiff base ligand, [Fe-II(qsal-COOH)(2)], were successfully prepared. The crystal structures from a single-crystal X-ray diffraction study were obtained at 100 and 170 K and yielded information regarding both the low-spin and high-spin states, without any crystal breakage being observed after the phase transition. Structural analysis was performed to visualize the origin of the SCO phenomenon in the [Fe-II(qsal-COOH)(2)] complex. We report that the fundamental requirements for an abrupt SCO, particularly in Fe-qsal complexes, are not only a combination of weak interaction effects, such as pi-pi, P4AE (parallel four-fold aryl embrace), and hydrogen bonding, but also the presence of solvents in the crystalline structure, since the solvent molecules can influence the interactions between the [Fe-II(qsal-X)(2)] molecules.
  • Misaki Ohkita; Aya Fujiwara; Tomoki Nishiyama; Masahiko Maekawa; Takayoshi KURODA-SOWA; Takashi Okubo
    X-RAY STRUCTURE ANALYSIS ONLINE 37 29 - 31 2021年06月 [査読有り]
     
    The structure of a dinuclear copper(I) complex, [Cu2I2(dma-acd)(2)] (dma-acd = 3,6-bis(dimethylamino)acridine), was determine by X-ray crystallography. The compound crystallizes in a monoclinic system and was characterized thus: P2(1)/n, a = 9.1930(5), b = 15.2507(7), c = 11.8959(5)angstrom, beta = 95.749(5)degrees, Z = 4, V = 1659.41(14)angstrom(3). The crystal structure was solved by direct methods and refined by full-matrix least-squares on F-2 to final values of R-1 = 0.0279 [I > 2 sigma(I)] and wR(2) = 0.0719 (all data).
  • Masahiko Maekawa; Kota Terada; Shoki Oda; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa
    INORGANICA CHIMICA ACTA 514 2021年01月 [査読有り]
     
    The reactions of [Ir(H)(2)(PPh3)(2)(Me2CO)(2)]X (X = PF6, BF4) with terpy in CHCl3, Me2CO and CH2Cl2 under Ar afforded three novel Ir(III)-hydride complexes 1-3 by the choices of solvents and anions. Ir(III)-terpy hydride complexes [Ir(H)(2)(PPh3)(2)(terpy-kappa(2)/N,N')]PF6 center dot CHCl3 (1) and [Ir(H)(2)(PPh3)(2)(terpy-kappa N-2,N')]BF4 center dot Me2CO (2) with two cis hydride atoms, two PPh3 and terpy-kappa N-2,N' possess a octahedral N2P2H2 coordination mode, while pincerlike Ir(III)-terpy hydride complex {[Ir(H)(PPh3)(2)(terpy-kappa(3)/N,N',N '')](BF4)(2)center dot 2CH(2)Cl(2)}(2) (3) with one hydride atom, two PPh3 and terpy-kappa N-3,N',N '' possess a octahedral N3P2H coordination mode. H-1 NMR analyses showed that the asymmetric and symmetric structures of three Ir(III)-terpy hydride complexes 1-3 are kept in solution. It was found that the significant H-1 NMR upfield shifts could be induced by the ring current effect from the phenyl groups of adjacent PPh3 ligands.
  • Ryuta Ishikawa; Takeshi Noda; Shunya Ueno; Takashi Okubo; Hirofumi Yamakawa; Ken-ichi Sakamoto; Satoshi Kawata
    Magnetochemistry 6 3 29 - 29 2020年07月 [査読有り]
     
    Herein, the syntheses, solid-state molecular structures, and characterization of two types of one-dimensional FeIII coordination polymers showing thermally induced spin crossover are reported. The reaction of [Fe(acen)Cl] (acen2− = N,N’-ethylenebis(acetylacetonylideneaminate) with 3,3′-bpy or 4,4′-bpy (bpy = bipyridine) produced zigzag and linear one-dimensional chain complexes, [Fe(acen)(3,3′-bpy)][BPh4] (1) or [NEt3H][Fe(acen)(4,4′-bpy)][BPh4]2·0.5(4,4′-bpy) (2), respectively, as confirmed by single crystal X-ray diffraction analysis. Variable-temperature single crystal X-ray diffraction measurements, continuous-wave X-band electron paramagnetic resonance (EPR) spectra, 57Fe Mössßauer spectra, and DC magnetic susceptibility data revealed that complex 1 exhibited a gradual and complete spin crossover at a transition temperature of 212 K, while complex 2 undergoes an incomplete spin crossover even at 400 K.
  • 壬生託人; 末永勇作; 大久保貴志; 前川雅彦; 黒田孝義
    Inorganic Chemistry Communications 114 2020年02月 [査読有り]
     
    Co-dioxolene complex [Co(DBCat)(pbqa))(PF6) (DBCat = 3,5-di-tert-butylcatechol, pbqa = (2-pyridylmethyl)bis (2-quinolylmethyl)amine), was prepared from methanol solution. Single crystal X-ray structural analysis revealed that the valence of the cobalt ion to be + III, as DBCat is formally a catecholate dianion, whereas the acetonitrile solution exhibits an MLCT absorption near 575 nm, suggesting it is present as hs-Co-II (SQ). Of note, this MLCT band disappears with decreasing temperature. This behavior suggests that [Co(DBCat)(pbqa)1(PF6) undergoes a temperature-dependent change from hs-Co-II(SQ) to ls-Co-III(Cat). Magnetic susceptibility vs. temperature data for the compound displayed a gradual variation over 250 K, due to intramolecular electron transfer in the solid-state as well. (Co(DBCat)(pbqa)](PF6) demonstrates valence tautomerism due to a strong pi-pi interaction between the quinoline rings of the ancillary ligand. Comparison of this pbqa compound to similar Co compounds provides further evidence for these conclusions.
  • Nobutaka Yoshimura; Atsushi Kobayashi; Wataru Genno; Takashi Okubo; Masaki Yoshida; Masako Kato
    Sustainable Energy & Fuels 4 7 3450 - 3457 2020年 [査読有り]
     

    Photocatalytic H2 evolution activity in iodide aqueous solution was improved by increasing the Ru(ii)–dye layer number on the Pt–TiO2 surface.

  • Masahiko Maekawa; Terumasa Hayashi; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa
    Inorganica Chimica Acta 497 2019年08月 [査読有り]
     
    The reaction of [Cu(MeCN)(4)]X (X = BF4, PF6) with 2,2': 5', 4 ''-terpyridine (2,2': 5', 4 ''-terpy) in MeOH/MeCN under Ar/C2H4 afforded 1-D Cu(I) coordination polymers {[Cu(2,2': 5', 4 ''-terpy)(MeCN)]BF4}(n) (1) and { { [Cu (2,2': 5', 4 ''-terpy)(MeCN)]PF6}(2)center dot H2O}(n) (2). In complex 1, the tetrahedral Cu(I) atoms are bridged by 2,2': 5', 4 ''-terpy in the head-to-tail fashion to form an infinite 1-D zigzag chain structure. In complex 2, there are two independent infinite 1-D zigzag chain structures along the b- and c-axises in the unit cell. The weak intermolecular pi center dot center dot center dot pi stacking interactions exist between opposite 2,2':5', 4 ''-terpy ligands. The PF6- anions are surrounded by four opposite MeCN molecules in two crossed zigzag chains. In contrast, the reaction of [ Cu( MeCN) 4] PF6 with 2,2':5', 4 ''-terpy in Me2CO/MeCN under Ar/C2H4 afforded Cu(I) metallomacrocycle [Cu-4(2,2':5', 4 ''-terpy) 4](PF6)(4)center dot 5Me(2)CO (3). Four Cu(I) atoms are bridged by the four 2,2':5', 4 ''-terpy in a head-to-tail fashion to afford a rhombic Cu(I) metallomacrocycle. One distorted Me2CO molecule is encapsulated in the central vacant space of [Cu-4(2,2':5', 4 ''-terpy)(4)](4+) core and two PF6- anions are sandwiched between the rhombic Cu(I) metallomacrocyclic layers. The reactions of Cu(NO3)(2)center dot 3H(2)O and Cu turnings with 2,2':5',4 ''-terpy in MeOH/MeCN under Ar afforded 1-D Cu(I) coordination polymer {[Cu(2,2':5', 4 ''-terpy)(MeCN)]NO3}(n) (4). It has been proved that complex 4 could be induced by the autoreduction of Cu(II) species to Cu(I) species.
  • Y. Suenaga; T. Mibu; T. Okubo; M. Maekawa; T. Kuroda-Sowa
    X-ray Struct. Anal. Online 35 10 61 - 62 2019年 [査読有り]
     
    The reaction of a methanol solution containing Co(BF4)(2)center dot 6H(2)O and (2-pyridylmethyl)bis(2-quinolylmethyl)amine (pbqa) afforded a dinuclear cobalt(II) complex, [Co-2(mu-F)(2)(pbqa)(2)](BF4)(2), where the two metal centers are doubly bridged by two fluoride ions. BF4- is a fluoride source. A temperature-dependent magnetic susceptibility measurement reveal that a strong spin orbit contribution with a zero-field splitting effect of two high-spin Co(II) ions. It crystallizes in the monoclinic space group C2/c with a = 24.9600(9)angstrom, b = 11.1533(3)angstrom, c = 20.0575(6)angstrom, alpha = 90 degrees, beta = 109.439(4)degrees, gamma = 90 degrees, V = 5265.4(3)angstrom(3), D-calc = 1.535 g/cm(3), and Z = 4. The R1 [I > 2 sigma(I)] and wR2 (all data) values are 0.0403 and 0.1018, respectively, for all 7897 independent reflections.
  • Y. Suenaga; T. Mibu; T. Okubo; M. Maekawa; T. Kuroda-Sowa
    Polyhedron 171 480 - 485 2019年 [査読有り]
     
    Two types of biscatechol, namely H(4)L1 (5,5'-(buta-1,3-diyne-1,4-diyl)bis(3-t-butylcatechol)) and H(4)L2 (5,5'-(ethyne-1,2-diyl)bis(3-t-butylcatechol)) were synthesized. In these ligands, two redox active catechol moieties are connected by one or two triple bonds. Also, tpa (tris(2-pyridylmethyl) amine), bpqa (bis(2-pyridylmethyl)(2-quinolylmethyl)amine) and pbqa ((2-pyridylmethyl)bis(2-quinolylmethyl)amine) were synthesized as terminal ligands of the tetracoordinated tripod type. In total, six dinuclear Co complexes were synthesized from these biscatechol and terminal ligands as follows: [Co-2(L1)(tpa)(2)](BF4)(2) (1), [Co-2(L1)(bpqa)(2)](PF6)(2) (2), [Co-2(L1)(pbqa)(2)](PF6)(2) (3), [Co-2(L2)(tpa)(2)](BF4)(2) (4), [Co-2(L2)(bpqa)(2)](PF6)(2) (5), [Co-2(L2)(pbqa)(2)](PF6)(2) (6). Of the six dinuclear Co complexes, complex 6, which was isolated as a mixed valent state Co-II(HS)-[SQ-Cat]-Co-III(LS) compound, showed an absorption intensity at around 703 nm (MLCT bands) that increased with increasing temperature in acetonitrile solution. In addition, an investigation of the magnetic properties of the complex 6 with SQUID showed that the chi T-M value gradually increased as the temperature increased from 150 to 380 K. This suggests that a transition from Co-III(LS) (S = 0) to Co-II(HS) (S = 3/2) accompanies the temperature rise. This means the steric hindrance and electronic effect of the quinolyl groups around the Co ion produce a coordination atmosphere weaker than that of pyridyl groups, with the result that the Co-III ions easily convert to Co-II ions. (C) 2019 Elsevier Ltd. All rights reserved.
  • Measuring the competition between bimolecular charge recombination and charge transport in organic solar cells under operating conditions
    Michael C. Heiber; Takashi Okubo; Seo-Jin Ko; Benjamin R. Luginbuhl; Niva A. Ran; Ming Wang; Hengbin Wang; Mohammad; Afsar Uddin; Han Young Woo; Guillermo C. Bazan; Thuc-Quyen Nguyen
    Energy & Environmental Science 11 3019 - 3032 2018年07月 [査読有り]
  • Takashi Okubo; Kento Himoto; Koki Tanishima; Sanshiro Fukuda; Yusuke Noda; Masanobu Nakayama; Kunihisa Sugimoto; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    Inorganic Chemistry 57 5 2373 - 2376 2018年03月 [査読有り]
     
    A new semiconducting 3D coordination polymer, [Cu2Br2(ttz)]n (1), with an acceptor bridging ligand, 1,2,4,5-tetrazine (ttz), was synthesized. The complex shows large absorption bands extending to the near-IR region, indicating a small band gap in the coordination polymer. This complex shows higher conductivity than those of [CuBr(pyz)]n (2), including pyrazine (pyz) with a higher lowest unoccupied molecular orbital level. We performed density functional theory band calculations using the VASP program to understand the electronic states and conducting paths of the coordination polymer.
  • Kento Himoto; Toshiya Horii; Takumi Syoji; Takashi Okubo; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    Inorganic Chemistry Communications 88 34 - 37 2018年02月 [査読有り]
     
    A new one-dimensional coordination polymer, [CuII(3-Py-CHO)]n (3-Py-CHO = 3-pyridinecarboxaldehyde), consisting of an infinite copper(I)-iodide ladder chain and a pendant ligand, 3-Py-CHO, was prepared and structurally characterized using X-ray diffraction analysis. This material shows semiconducting properties with a relatively small activation energy, as shown by impedance measurements. We also estimated the electrical conductivity from a current-voltage (I-V) curve measured from a single crystal of the coordination polymer.
  • Kento Himoto; Toshiya Horii; Shoki Oda; Shimpei Suzuki; Kunihisa Sugimoto; Takashi Okubo; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    Acta Crystallographica Section E: Crystallographic Communications 74 Pt 2 233 - 236 2018年02月 [査読有り]
     
    A new heterometallic CuI-NiII coordination polymer, poly[[tetra-3-iodido-2-iodido-bis(3-piperidine-1-dithiocarbamato)propionitrilepentacopper(I)nickel(II)] chloroform monosolvate], {[CuI 5NiIII5(C6H10NS2)2(C3H5N)]CHCl3}n, has been synthesized and structurally characterized. This coordination polymer consists of an NiII mononuclear unit of NiII(Pip-dtc)2 (Pip-dtc is piperidine-1-dithiocarbamate) and a pentanuclear copper(I) cluster unit of Cu5I5(CH3CH2CN). The NiII ion, which lies on an inversion centre, is surrounded by four S atoms in a square-planar coordination geometry while all CuI ions have distorted tetrahedral coordination geometries. In the pentanuclear copper(I) cluster unit, a mirror plane passes through one CuI ion and three I ions. All the S atoms in NiII(Pip-dtc) are also coordinated by the CuI ions, forming an infinite zigzag chain structure along the b-axis direction. The chains are weakly connected by solvent CHCl3 molecules via Cl I [3.653 (1) Å] and Cl S [3.4370 (1) Å] short-contact interactions.
  • K. Himoto; S. Suzuki; T. Okubo; M. Maekawa; T. Kuroda-Sowa
    New J. Chem., 2018, 42, 3995 42 6 3995 - 3998 2018年 [査読有り]
     
    A novel mixed-valence coordination polymer [CuI4CuIIBr4(dmpip-dtc)2(CH3CN)]n (dmpip-dtc = dimethylpiperidine-dithiocarbamate) with an infinite one-dimensional structure was synthesized and structurally characterized using X-ray diffraction. The electronic properties of the coordination polymer were investigated by UV-vis-NIR spectroscopy. Impedance measurement results demonstrated that this complex has a narrow bandgap, inducing semiconducting behavior.
  • Takayoshi Kuroda-Sowa; Rina Isobe; Norifumi Yamao; Tomohiro Fukumasu; Takashi Okubo; Masahiko Maekawa
    POLYHEDRON 136 74 - 78 2017年11月 [査読有り]
     
    The preparation and magnetic properties of four Fe(11) Schiff-base complexes, [Fe(qsal(x))(2)] (Hqsal(x) = N-(8'-quinoly1)-2-hydroxy-5-halogeno-l-salicylaldimine; X = F(1), C1(2), Br(3), 1(4)) are reported. X-ray single crystal structure analyses of 1 and 2 reveal that Fe(II) ions in both complexes are coordinated by two qsalx ligands in meridional fashion. Molecular packing of 1 shows that a non-planar qsal(F) ligand interacts with neighboring two qsal(F) ligand's through pi-pi interactions, while that of 2 shows that two planar qsal(cl) ligands interact each other through pi-pi interaction. Although the magnetic property of 1 shows a high spin state at all the temperature range measured, the chi T-T plots of 2, 3, and 4 show gradual spin crossover behaviors with T1/2 of 308 K, 341 K, and 340 K, respectively. (C) 2017 Elsevier Ltd. All rights reserved.
  • Masahiko Maekawa; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata
    INORGANICA CHIMICA ACTA 467 204 - 211 2017年10月 [査読有り]
     
    The reactions of CuX2 center dot nH(2)O (X = ClO4, BF4), Cu turnings and 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz) with excess 1,5-cyclooctadiene (cod) in Me2CO under C2H4 afforded dinuclear Cu(I)-bptz/eta(2), eta(2)-cod-X complexes {(1) and (4)} and dinuclear Cu(I)-2,5-H(2)bptz/eta(2), eta(2)-cod-X complexes {(2) and (5)}. In complexes 1 and 4, each Cu(I) atom is coordinated by two chelate N atoms of bptz and two C=C bonds of eta(2), eta(2)-cod in the distorted tetrahedral geometry to produce a transoid dinuclear structure. It should be noted that the redox state of the central tetrazine ring is electrochemically neutral. In complexes 2 and 5, each Cu(I) atom is coordinated by two chelate N atoms of 2,5-H(2)bptz and two C=C bonds of eta(2), eta(2)-cod in the distorted tetrahedral geometry to afford a transoid dinuclear structure in the 2,5-dihydro form. In contrast, the reactions of Cu(BF4)(2)center dot nH(2)O, Cu turnings and bptz with excess 2,5-norbornadiene (nbd) in MeEtCO under C2H4 afforded Cu(I)-2,5-H(2)bptz/eta(2)-nbd-BF4 complex (6). Each Cu(I) atom is coordinated by two chelate N atoms in bptz and one C=C bond in eta(2)-nbd to form a transoid dinuclear structure in the 2,5-dihydro form. These facts show that the flexible cod can preferentially produce a Cu(I)cyclodiene complex in the eta(2), eta(2)-mode (complexes 1, 2, 4 and 5) while the rigid nbd can produce a Cu (I)-cyclodiene complex in the eta(2)-mode (complex 6). Furthermore, the reaction of Cu(NO3) center dot 3H(2)O, Cu turnings and bptz with excess nbd in Me2CO under C2H4 afforded tetranuclear Cu(I)-4,5-H(2)bptz-NO3 complex (7) containing a unique anionic [Cu-2(nbd)(NO3)(4)](2) moiety. In the cationic [Cu-4(4,5H(2)bptz) 4] 4+ moiety, four Cu(I) atoms are bridged by four 4,5-H(2)bptz ligands to form a [4 x 4] grid-like tetranuclear structure with two 4,5-H(2)bptz ligands lying above the Cu4 mean plane and two lying below. In the anionic [Cu-2(nbd)(NO3)(4)](2) moiety, the two Cu atoms are bridged by one nbd ligand in the mu(2)-eta(2), eta(2)-mode. (C) 2017 Elsevier B. V. All rights reserved.
  • Shin-ichi Naya; Junpei Yamauchi; Takashi Okubo; Hiroaki Tada
    LANGMUIR 33 40 10468 - 10472 2017年10月 [査読有り]
     
    The establishment of technology for rapid and complete removal and mineralization of harmful phenolic compounds from water is of great importance for environmental conservation. Visible-light irradiation (lambda > 430 nm, light intensity integrated from 420 to 485 nm = 6.0 mW cm(-2)) of Au nanoparticle (NP)-loaded TiO2 (Au/TiO2) in dilute aqueous solutions of bisphenol A (BPA) and p-cresol (PC) causes degradation of the phenols. The addition of trimethylstearylammonium chloride (C(18)TAC) enhances the adsorption of BPA on Au/TiO2 to greatly increase the rate of reaction. Consequently, 10 mu M phenols are completely removed from the solutions within 2.5 h irradiation, and prolonging irradiation time to 24 h quantitatively oxidizes BPA to CO2. Dynamic light scattering zeta-potential measurements indicate that a C(18)TAC bilayer or admicelle is formed on the Au/TiO2 particle surface at C(18)TAC concentration >50 mu M. The action spectrum for reaction shows that this reaction is driven by the Au NP localized surface plasmon resonance excitation-induced interfacial electron transfer from Au to TiO2. We propose a possible reaction scheme on the basis of the experimental results including intermediate analysis.
  • Masahiko Maekawa; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata
    CHEMISTRYSELECT 1 13 3812 - 3822 2016年08月 [査読有り]
     
    The reactions of [Cu(MeCN)(4)]BF4 or [Cu(C2H4)(n)]ClO4 complexes with 4,6-bis(2-pyridyl)pyrimidine (bppym) in Me2CO under C2H4 afforded dinuclear Cu(I)-bppym/C2H4 adducts [Cu-2-(bppym)(C2H4)2](BF4)(2)center dot Me2CO (1) and [Cu-2(bppym)(2)(C2H4)(2)](ClO4)(2)center dot Me2CO (2), respectively. One Cu(I) atom is coordinated by bppym and C2H4 in a distorted trigonal-planar geometry. The other Cu(I) atom is coordinated by bppym, Me2CO, and C2H4 toward a distorted tetrahedral geometry. The reaction of [Cu(MeCN)(4)]BF4 with 2,3-bis(2-pyridyl)pyrazine (bppz) in MeOH under C2H4 afforded a Cu(I)-bppz coordination polymer {[Cu-2(bppz)(2)](BF4)(2)center dot MeOH} n (3). Two Cu(I) atoms are alternately bridged by two bppz to form a 1-D zigzag-chain structure. Each Cu(I) coordination sphere is largely distorted from a normal tetrahedral structure toward a square planar structure. The reaction of [Cu(MeCN)(4)]PF6 with 2,4,6-tris(2-pyridyl)-s-triazine (tptz) in MeEtCO under C2H4 afforded a tetranuclear Cu(I)-tptz/C2H4 adduct [Cu-4(tptz)(2)(C2H4)(2)(MeCN)(2)](PF6)(4)center dot MeEtCO (4b). Two Cu(I) atoms are bridged by the central triazine ring, the 2-pyridyl group, the central triazine ring, and the 2-pyridyl group in a different tptz to form a double helical structure. The other Cu(I) atom is coordinated by the central triazine ring, the 2-pyridyl group, MeCN, and C2H4 in a distorted tetrahedral geometry. The reaction of [Cu(MeCN)(4)]PF6 with tetra-2-pyridylpyrazine (tppz) in MeOH under C2H4 afforded a tetranuclear Cu(I)-tppz complex [Cu-4(tppz)(2)(MeCN)(4)](PF6)(4)center dot MeOH (5a). Each Cu(I) atom is coordinated by the central pyrazine ring, the 2-pyridyl group, the 2-pyridyl group in a different tppz, and MeCN in a distorted tetrahedral geometry. These four Cu(I) atoms are bridged by the two opposite tppz ligands to form a unique tetranuclear Cu(I) cage structure.
  • Masahiko Maekawa; Yukimi Kubo; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata
    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY 1 78 - 91 2016年01月 [査読有り]
     
    A new type of Ir-III metalloligands containing an unsaturated nitrogen coordination site, [Ir(H)(2)(PPh3)(2)(pprd)]BF(4)2CHCl(3) (1), [Ir(H)(2)(PPh3)(2)(Me(2)bpm)]BF4CHCl3 (2), {[Ir(H)(2)(PPh3)(2)(Me(2)bpm)]PF6CHCl3}(4) (3), [Ir(H)(2)(PPh3)(2)(biqz)]BF(4)2CHCl(3) (4), and [Ir(H)(2)(PPh3)(2)(biqz)]PF6 (5), have been prepared by reaction of [Ir(H)(2)(PPh3)(2)(Me2CO)(2)]X (X = BF4 or PF6) with 4-(2-pyridyl)pyrimidine (pprd), 6,6-dimethyl-4,4-bipyrimidine (Me(2)bpm), or 4,4-biquinazoline (biqz). Subsequently, three novel heterometallic Ag-I-Ir-III hydride coordination polymers, {[Ir(H)(2)(-pprd)(PPh3)(2)Ag(-CF3COO)]BF4Me2CO}(n) (6), {[Ir(H)(2)(-biqz)(PPh3)(2)Ag-2(-CF3COO)(3)]Me2CO}(n) (7), and {[Ir(H)(2)(-Me(2)bpm)(PPh3)(2)Ag-2(-CF3COO)(2)]PF(6)2Me(2)CO}(n) (8) have been constructed by reaction of the Ir-III metalloligands 1, 3, and 5 with AgCF3COO. In coordination polymer 6, the [Ir(H)(2)(PPh3)(2)(pprd)](3+) units are linked through the Ag-I atoms to form a 1D zigzag chain structure. In coordination polymer 7, the dinuclear [Ag-2(-CF3COO)(3)](-) units are linked through the terminal N atoms of biqz in two different [Ir(H)(2)(PPh3)(2)(biqz)](3+) units to form a 1D zigzag chain structure. In coordination polymer 8, the [Ag-2(-CF3COO)(2)] frameworks are linked through the terminal N atoms of Me(2)bpm and the Ir-III atom in two different [Ir(H)(2)(PPh3)(2)(Me(2)bpm)](3+) units to form a waved rectangular cavity. These waved rectangular cavities are connected to each other to afford a unique 2D sheet structure.
  • Kenji Nakatani; Kento Himoto; Yuki Kono; Yuuki Nakahashi; Haruho Anma; Takashi Okubo; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    CRYSTALS 5 2 215 - 225 2015年06月 [査読有り]
  • Masahiko Maekawa; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata
    INORGANICA CHIMICA ACTA 426 64 - 70 2015年02月 [査読有り]
     
    The reaction of [Cu(MeCN)(4)]PF6 with 3,5-bis(2-pyridyl)-1H-1,2,4-triazole (Hbptrz) in MeOH under C2H4 afforded the colorless needle crystals of [Cu-2(bptrz)(C2H4)(2)]PF6 center dot MeOH (1). The X-ray crystallographic study showed that there are two [Cu-2(bptrz)(C2H4)(2)](+) cation moieties, two PF6 anions and two solvated MeOH molecules in the unit cell. This result indicates that the central triazole ring was deprotonated to produce the anionic bptrz ligand. Each Cu(I) atom is coordinated by two chelate N atoms of bptrz and the C=C bond of C2H4 in the trigonal-planar geometry to produce a notable dinuclear Cu(I)-bptrz/C2H4 adduct bearing the anionic bptrz in the transoid conformation. In contrast, the reaction of Cu(NO3)(2)center dot H2O, Cu turnings and 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine (4-bptz) in Me2CO under C2H4 gave black brick crystals of {[Cu-4(4,5-H-2-4-bptz)(2)(C2H4)(2)(NO3)(4)]center dot Me2CO center dot 0.5H(2)O}(n) (2). This result indicates that 3,6-bis(4-pyridyl)-4,5-dihydro-1,2,4,5-tetrazine (4,5-H-2-4-bptz) was produced by the two-electron reduction of 4-bptz. Four Cu(I) atoms are bridged by two 4,5-H-2-4-bptz and four NO3 anions to form two distinct rectangular [Cu-4(4,5-H-2-4-bptz)(2)(NO3) 4] frameworks. Furthermore, these rectangular [Cu-4(4,5-H-2-4-bptz)(2)(NO3)(4)] subunits are linked via the N atom in the central 4,5-dihydrotetrazine ring each other to generate a unique 2-D Cu(I)-4,5-H-2-4-bptz/C2H4-NO3 coordination polymer with a channel structure along the a-axis. Thermogravimetric analysis (TG-DTA) showed that complexes 1 and 2 were thermochemically stable to a relatively high temperature. (C) 2014 Elsevier B.V. All rights reserved.
  • D. Umeyama; N. P. Funnell; M. J. Cliffe; J. A. Hill; A. L. Goodwin; Y. Hijikata; T. Itakura; T. Okubo; S. Horike; S. Kitagawa
    CHEMICAL COMMUNICATIONS 51 64 12728 - 12731 2015年 [査読有り]
     
    The structure of a glass obtained by the melt quenching of a two-dimensional (2D) coordination network was examined. X-ray analyses disclosed a 2D-to-0D structural transformation before and after glass formation. The mechanism is unique to coordination compounds, as it is characterized by labile and flexible coordination bonds.
  • Yusaku Suenaga; Honami Inada; Masataka Inomata; Ryotaro Yamaguchi; Takashi Okubo; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    CHEMISTRY LETTERS 43 4 562 - 564 2014年04月 [査読有り]
     
    Trinuclear Co(III) complex [Co-3(III)(tpa)(3)(L)](BF4)(4) (tpa: tris-(2-pyridylmethyl)amine, H6L: 2,3,6,7,10,11-hexahydroxytriphenylene) is prepared from methanol solution. Single-crystal structure analysis revealed that the valency of the three cobalt ions is +3 and that the tris(dioxolene) bridging ligand is formally in the -5 [cat,cat,sq] oxidation state. This complex is stable in the entire temperature range investigated. Various-temperature magnetic susceptibility data for the compound displayed little variation in the range 2-300K, and the reason caused the distinct charge distribution on Co-L (L: bridging ligand) by the natural rigidity of the tripodal ligands. Also, its CH3CN solution exhibits a very strong NIR absorption arising from an internal ligand transition within the triphenylene ligand. Cyclic voltammetry (CV) measurements in CH3CN solution show three reversible cat sq redox waves for the triphenylene ligand.
  • Masahiko Maekawa; Ai Minamino; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata
    INORGANICA CHIMICA ACTA 414 257 - 263 2014年04月 [査読有り]
     
    The reactions of [Cu(MeCN)(4)](X) (X = BF4 or PF6) with 4,4'-biquinazoline (biqz) in MeOH under C2H4 afforded brown plate crystals of {[Cu-4(biqz)(2)(MeCN)(4)(MeOH)(4)](BF4)(4)}(n) (1) and orange prismatic crystals of {[Cu-4(biqz)(2)(MeCN)(8)](PF6)(4)}(n) (2), respectively. In both of complexes 1 and 2, two Cu(I) atoms are bridged by two biqz ligands to form a 14-membered Cu4C6N4 framework. Furthermore, the Cu4C6N4 frameworks are linked by the two chelate and bridging sites of biqz to generate a 1-D double-chain Cu(I) coordination polymer. It should be noted that two N atoms in the chelate site of the biqz ligand does not act as a normal bidentate chelate mode but form a bridge between two Cu atoms in an unidentate bridging mode. In contrast, the reaction of [Cu(C2H4)(n)]ClO4 with biqz in Me2CO under C2H4 afforded orange plate crystals of polymeric Cu(I)-biqz/C2H4 adduct {[Cu-2(biqz)(C2H4)(2)](ClO4)(2)center dot Me2CO}(n) (3). The Cu atom is coordinated by two N atoms of biqz in the chelate site and the C=C bond of C2H4 in a rather distorted trigonal-planar geometry. The other Cu atom is coordinated by two N atom of two biqz ligands in the exo bridging site and the C=C bond of C2H4 in a trigonal-planar geometry to form a 1-D zigzag-chain structure. It was proved that the Cu(I) coordination polymers bridged by the biqz ligand in the different coordination modes can be preferentially produced by the choices of the precursor Cu(I) complexes. The thermogravimetric analysis (TG-DTA) measurements showed that Cu(I)-biqz-{BF4, PF6} complexes 1 and 2 were thermochemically stable to a relatively high temperature (330-340 degrees C). (C) 2014 Elsevier B. V. All rights reserved.
  • Takashi Okubo; Haruho Anma; Yuuki Nakahashi; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    POLYHEDRON 69 103 - 109 2014年02月 [査読有り]
     
    New mixed-valence coordination polymers {[(Cu5CuI5L2)-Cu-I-I-II(C2H5CN)(2)]center dot CHCl3)(n) (L = piperidinedithiocarbamate and hexamethyl-dithiocarbamate) with isomorphous infinite one-dimensional (1D) structures were prepared and structurally characterized via X-ray diffraction. These complexes comprised a mononuclear Cu(II) unit, (CuL2)-L-II, and a pentanuclear Cu(I) cluster unit, (Cu5I5)-I-I(C2H5CN)(2). Impedance measurements demonstrated that these Cu(I)-Cu(II) mixed-valence 1D coordination polymers displayed semiconducting behavior with low conductivities. (C) 2013 Elsevier Ltd. All rights reserved.
  • Masahiko Maekawa; Takeshi Miyazaki; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata; Susumu Kitagawa
    INORGANICA CHIMICA ACTA 410 46 - 53 2014年01月 [査読有り]
     
    The reaction of [Cu(C2H4)n]NO3, Cu turnings, 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz), and ferrocene in Me2CO under C2H4 afforded black crystals of [Cu-4(4,5-H(2)bptz)(4)][Cu(C2H4)(NO3)(2)](2)(NO3)(2)center dot 2Me(2)CO (7). In the [Cu-4(4,5-H(2)bptz)(4)](4+) cation moiety, four Cu(I) atoms are bridged by four 4,5-H(2)bptz ligands to form a [4 x 4] grid-like tetranuclear structure. In the [Cu(C2H4)(NO3)(2)] anion moiety, the Cu atom is coordinated by two NO3 anions in the unidentate coordination mode and by the C=C bond of C2H4 to form a mononuclear Cu(I)-C2H4 adduct in the trigonal-planar geometry. It should be noted that two anionic Cu(I)-C2H4 adducts [Cu(C2H4)(NO3)(2)] are present as a co-crystal. The similar reaction of Cu(BF4)(2)center dot H2O, Cu turnings, bptz, and ferrocene in MeEtCO under C2H4 afforded colorless crystals of [Cu-2(bpdpyz)(C2H4) (2)](BF4)(2) (9). In the [Cu-2(bpdpyz)(C2H4)(2)](2+) cation moiety, each Cu(I) atom is coordinated by two chelate N atoms of bpdpyz and the C=C bond of C2H4 to afford an unusual cisoid dinuclear structure. This result shows that 3,6-bis(2-pyridyl)-4,5-dihydropyridazine (bpdpyz) can be produced by the cycloaddition of bptz with C2H4 via a Diels-Alder addition and retro-Diels-Alder elimination of dinitrogen to form complex 9. In contrast, the reaction of Cu(BF4)(2)center dot H2O, Cu turnings, and bptz in Me2CO in the absence of ferrocene afforded black crystals of [Cu-4(4,5-H(2)bptz)(4)](BF4)(4)center dot Me2CO (12). Although the apparent structure of the [Cu-4(4,5-H(2)bptz)(4)](4+) cation moiety is similar to that of the [Cu-4(4,5-H(2)bptz)(4)](4+) cation moiety in complex 7, the shape of the Cu-4 framework is closer to a square structure, resulting in the adjacency of the two opposite tetrazine rings. The preparations and structural diversity of Cu(I)-C2H4 adducts with the related bptz ligands are described in addition to related previous results. (C) 2013 Elsevier B.V. All rights reserved.
  • Y. Suenaga; M. Inomata; K. Uwai; K. Okuda; T. Okubo; M. Maekawa; T. Kuroda-Sowa
    X-ray Struct. Anal. Online 30 57 - 58 The Japan Society for Analytical Chemistry 2014年 [査読有り]
     
    The reaction of a methanol solution containing Co(BF4)2·6H2O and tris(2-pyridylmethyl)amine (tpa) afforded the unexpected dinuclear cobalt(III)-peroxo complex [Co2(μ-F)(μ-O2)(tpa)2](BF4)3, where the two metal centers are simultaneously doubly bridged by one fluoride ion such that BF4- is a fluoride source. It crystallizes in the triclinic space group P1 with a = 10.452(3)Å, b = 12.529(3)Å, c = 16.708(5)Å, α = 106.410(4)°, β = 106.916(4)°, γ = 90.2807(13)°, V = 1999.0(9)Å3, Dcalc = 1.678 g/cm3, and Z = 2. The R1 [I > 2σ(I)] and wR2 (all data) values are 0.0450 and 0.1679, respectively, for all 9093 independent reflections.
  • T. –S. Kim; H. Murata; T. Okubo; T. Mitani
    Science and Technology of Advanced Materials 5 325 - 329 2014年 [査読有り]
  • Naoya Tanaka; Takashi Okubo; Haruho Anma; Kyung Ho Kim; Yoshie Inuzuka; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    European Journal of Inorganic Chemistry 19 3384 - 3391 2013年07月 [査読有り]
     
    New mixed-valence CuI-CuII 1D coordination polymers of the structure [CuI 2CuIIX2(Pip- dtc)2(CH3CN)2]n [Pip-dtc = piperidine-1-carbodithioate X = Br (1a), I (1b)] containing a dithiocarbamate derivative have been synthesized and structurally characterized by X-ray diffraction. The 1D infinite chains were formed from mononuclear copper units [Cu(Pip-dtc)2] connected by bromido- or iodido-bridged copper dinuclear units that include acetonitrile ligands {i.e., [Cu2X 2(CH3CN)2]}. Evaluation of the magnetic properties of 1a and 1b revealed that these complexes displayed relatively strong antiferromagnetic interactions [J = -20.4 cm-1 (1a) and J = -18.8 cm-1 (1b)] between unpaired electrons of the copper(II) ions through the dinuclear halido-copper(I) units. Impedance spectroscopy revealed that complexes 1a and 1b exhibit intriguing semiconducting properties at activation energies of Ea = 0.78 eV (1a) and Ea = 0.62 eV (1b). Coordination polymers 1a and 1b were then adopted as the sensitizing material in dye-sensitized solar cells (DSSCs). New halido-bridged mixed-valence CuI-CuII coordination polymers with 1D infinite chain structures have been synthesized and structurally characterized The complexes show a relatively strong antiferromagnetic interaction and interesting semiconducting behavior. These coordination polymers were applied as sensitizing materials for DSSCs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Okubo T; Anma H; Maekawa M; Kuroda-Sowa T
    Acta crystallographica. Section E, Structure reports online 69 5 m275 - m276 2013年05月 [査読有り]
     
    The reaction of Cu(Hm-dtc)2 (H2m-dtc is azepane-1-carbodithioic acid), CuBr2 and methyl isothiocyanate yielded the title mixed-valence nonanuclear CuI/CuII compound, [Cu 9Br5(C7H12NS2) 5] or [CuI 8CuIIBr5(Hm-dtc)5], encapsulating a bromide anion in the center of the Cu9Br 4S10 cluster cage. The cage consists of a mononuclear CuII unit [Cu(Hm-dtc)2], three μ4-bridging Hm-dtc- ligands, eight CuI ions with distorted tetrahedral or trigonal pyramidal coordination geometries and four μ2-bridging bromide anions. The incorporated central bromide anion interacts with nine Cu ions with shorter Cu - Br separations than the sum of the van der Waals radii for Cu and Br.
  • Takashi Okubo; Haruho Anma; Naoya Tanaka; Kento Himoto; Shu Seki; Akinori Saeki; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    CHEMICAL COMMUNICATIONS 49 39 4316 - 4318 2013年 [査読有り]
     
    A novel mixed-valence Cu(I)-Cu(II) coordination polymer with an infinite two-dimensional structure, [(Cu3CuBr3)-Cu-I-Br-II(3,5-Dmpip-dtc)(2)](n) (3,5-Dmpip-dtc(-) = 3,5-dimethylpiperidine dithiocarbamate), was prepared, and its structure was characterized by X-ray diffraction. It shows semiconducting behavior with a relatively small activation energy and high carrier mobility, which were investigated using impedance spectroscopy and flash photolysis time-resolved microwave conductivity measurements, respectively.
  • Masahiko Maekawa; Takeshi Miyazaki; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata; Susumu Kitagawa
    DALTON TRANSACTIONS 42 12 4258 - 4266 2013年 [査読有り]
     
    The reaction of Cu(ClO4)center dot 6H(2)O, Cu turnings, and 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz) in Me2CO under C2H4 afforded brownish-red needle crystals of {[Cu-2(bptz(center dot-))(C2H4)(2)](ClO4)}(2) (1) as a minor product and brown plate crystals of [Cu-2(2,5-H(2)bptz)(C2H4)(2)](ClO4)(2)center dot 2Me(2)CO (2). The X-ray crystallographic study showed that complex 1 is composed of two independent [Cu-2(bptz(center dot-))(C2H4)(2)](+) cation moieties and two ClO4- anions. In both of the cation moieties, each Cu(I) atom is coordinated by two chelate N atoms of bptz(center dot-) and the C=C bond of C2H4 in the trigonal-planar geometry to form a unique transoid dinuclear Cu(I)-bptz(center dot-)/C2H4 adduct bearing a metal-stabilized tetrazine anion radical, bptz(center dot-), which was produced by the one-electron reduction of bptz. In contrast, complex 2 consists of one [Cu-2(2,5-H(2)bptz)(C2H4)(2)](2+) cation moiety, two ClO4- anions, and two solvated Me2CO molecules. Each Cu(I) atom is coordinated by two chelate N atoms of 2,5-H(2)bptz and the C=C bond of C2H4 in the trigonal-planar geometry to afford a transoid dinuclear Cu(I)-C2H4 adduct with 2,5-H(2)bptz, which was produced by the two-electron reduction of bptz. Additionally, the similar reaction of Cu(ClO4)center dot 6H(2)O, Cu turnings, and bptz in Me2CO or MeEtCO under C2H4 in the presence of ferrocene afforded orange brick crystals of [Cu-2(bpdpyz)(C2H4)(2)]- (ClO4)(2)center dot Me2CO (3) and [Cu-2(bpdpyz)(C2H4)(2)](ClO4)(2) (4), respectively, together with complex 1 in higher yield. This result shows that 3,6-bis(2-pyridyl)-4,5-dihydropyridazine (bpdpyz) was produced by the cyclo-addition of bptz with C2H4 via a Diels-Alder addition and retro-Diels-Alder elimination of dinitrogen. In complexes 3 and 4, each Cu(I) atom is coordinated by two chelate N atoms of bpdpyz and the C=C bond of C2H4 to afford an unusual cisoid dinuclear Cu(I)-C2H4 adduct. Further attempts to react excess [Cu(C2H4)(n)]ClO4 with bptz in Me2CO under C2H4 afforded black brick crystals of [Cu-4(4,5-H(2)bptz)(4)](ClO4)(4)center dot 2Me(2)CO (5) together with complex 1. Complex 5 is the first [4 x 4] grid-like tetranuclear Cu(I) complex constructed by the combination of Cu(I) ion and 4,5-H(2)bptz. The four Cu(I) atoms are spanned by four 4,5-H(2)bptz ligands, with two lying above the Cu-4 mean plane and two lying below. In contrast, the similar reaction of excess [Cu(C2H4)(n)]ClO4 with bptz in Me2CO under C2H4 in the presence of ferrocene afforded reddish-brown brick crystals of {[Cu-2(2,5-H(2)bptz)(C2H4)(2)](ClO4)(2)}(2)center dot Me2CO (6) together with complexes 1 and 5. Complex 6 is composed of two independent [Cu-2(2,5-H(2)bptz)(C2H4)(2)](2+) cation moieties, four ClO4- anions, and a solvated Me2CO molecule. It is interesting that the structures of the two [Cu-2(2,5-H(2)bptz)(C2H4)(2)](2+) cation moieties are different: one has a nearly planar structure and the other possesses a boat conformation owing to the bent central dihydrotetrazine ring.
  • Takashi Okubo; Naoya Tanaka; Haruho Anma; Kyung Ho Kim; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    POLYMERS 4 3 1613 - 1626 2012年09月 [査読有り]
     
    One-dimensional (1D) halide-bridged Cu(I)-Ni(II) heterometal coordination polymers containing a hexamethylene dithiocarbamate (Hm-dtc) ligand have been synthesized and crystallographically characterized. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the coordination polymers were estimated using UV-Vis-NIR and photoelectron spectroscopies, and it was revealed that these coordination polymers have appropriate HOMO levels for use as dye sensitizers. Direct-current electrical conductivity measurements and impedance measurements indicated that these 1D Cu(I)-Ni(II) heterometal coordination polymers were insulators (sigma(300K) < 10(-12) S cm(-1)). In addition, the coordination polymers were used as sensitizing materials in dye-sensitized solar cells (DSSCs). DSSCs with 1D Cu(I)-Ni(II) heterometal coordination polymers showed lower performances than those with 1D halide-bridged Cu(I)-Cu(II) mixed-valence coordination polymers.
  • Kyung Ho Kim; Chiaki Takahashi; Takashi Okubo; Yoshio Abe; Midori Kawamura
    APPLIED SURFACE SCIENCE 258 20 7809 - 7812 2012年08月 [査読有り]
     
    We investigate the properties of NiO thin films prepared by sol-gel solution and the photovoltaic performance of bulk-heterojunction (BHJ) solar cells based on NiO thin films as anode buffer layers with various film thickness and amorphous-crystalline phase. Optoelectronic properties and surface morphology of NiO films strongly depend on the thickness and phase of the NiO. The performance of solar cells based on nanocrystaline (nc-) NiO exhibits better photovoltaic characteristics in comparison to those employing an amorphous (a-) NiO. The obtained power conversion efficiency (PCE, eta) of a solar cell with a 20-nm-thick nc-NiO is 2.24%, with a short-circuit density (J(SC)) of 7.77 mA/cm(2), open-circuit voltage (V-OC) of 0.57 V, and fill factor (FF) of 0.50. (C) 2012 Elsevier B.V. All rights reserved.
  • Masahiko Maekawa; Yukimi Kubo; Kunihisa Sugimoto; Toshie Minematsu; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata
    POLYHEDRON 40 1 145 - 152 2012年06月 [査読有り]
     
    The reaction of [Ir(H)(2)(PPh3)(2)(Me2CO)(2)]BF4 with 2,2'-bipyimidine (bpym) in CHCl3 afforded the yellow needle crystals of mononuclear Ir(III)-bpym/hydride complex [Ir(H)(2)(PPh3)(2)(bpym)]BF4 center dot 4CHCl(3) (1). In contrast, when CH2Cl2 or CHCl3 solution of [Ir(H)(2)(PPh3)(2)(Me2CO)(2)]BF4 were layered by the THF solution of bpym, red brick crystals of dinuclear Ir(III)-bpym/hydride complex [Ir-2(H)(4)(PPh3)(4)(bpym)](BF4)(2)center dot 2CH(2)Cl(2)center dot 2THF (2) and orange brick crystals of [Ir-2(H)(4)(PPh3)(4)(bpyrn))(BF4)(2)center dot 2CHCl(3) (3) were solvent-selectively formed. The UV-Vis spectra of complexes 1-3 in the solid state demonstrated that the absorptions of complexes 2 (495 nm) and 3 (510 nm) exhibited a significant red-shift relative to that (420 nm) of complex 1. Complexes 1-3 redissolved in CD2Cl2 gave several well-resolved H-1 NMR signals at 23 degrees C. It is noteworthy that all H-1 NMR signals of the coordinated pyrimidine rings in complexes 1-3 were shifted to the upfield region relative to those of the metal-free bpym ligand, in which the coordination shifts (Delta delta = delta(complex) - delta(metal-free)) are {-0.12 (H-6.6'), -0.73 (H-4.4') and -0.55 (H-5.5') ppm} for complex 1, {-0.81 (H-4.4') and -0.67 (H-5.5') ppm} for complex 2, and {-0.72 (H-4.4') and -0.58 (H-5.5') ppm} for complex 3. It was proved that unusual upheld shifts can be caused by the diamagnetic anisotropic ring current effect between the adjacent bpym and phenyl groups of PPh3. Thermogravimetric analysis (TG-DTA) showed that Ir(III)-bpym/hydride complexes 1-3 were thermochemically stable to a relatively high temperature near 330 degrees C. (C) 2012 Elsevier Ltd. All rights reserved.
  • Akira Funabiki; Hiroki Sugiyama; Tomoyuki Mochida; Kunihiro Ichimura; Takashi Okubo; Ko Furukawa; Toshikazu Nakamura
    RSC Advances 2 3 1055 - 1060 2012年02月 [査読有り]
     
    The dry grinding of a mixture of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and silica nanoparticles has produced powdery (BEDT-TTF)-silica nanocomposites. The (BEDT-TTF)-silica nanocomposites are readily doped with iodine in hexane dispersion to give powdery nanocomposites of (BEDT-TTF) 2I 3-silica. XRD and TEM measurements suggest that (BEDT-TTF) 2I 3 in the nanocomposite exists as shell layers of core-shell-type nanoparticles and as nanometre-sized crystals incorporated into hollow sites of aggregated silica nanoparticles. Magnetic susceptibility measurements reveal that the nanocomposites accompanied a large number of Curie spins attributable to surface molecules of the core-shell-type nanoparticles. The nanocomposites show a magnetic susceptibility change corresponding to the metal-insulator transition of α-(BEDT-TTF) 2I 3 in a broad temperature range of 110-140 K, which is attributed to the properties of the nanocrystalline components. Doping in diethyl ether dispersion leads to higher amounts of the nanocrystalline component being obtained. The doping of (BEDT-TTF)-silica nanocomposites by dry grinding produces a paramagnetic powder containing amorphous (BEDT-TTF) 2I 3, which possesses a Curie spin concentration of 50%. The effects of annealing on these nanocomposites are investigated. The electrical conductivity of the compaction pellets of (BEDT-TTF)-silica nanocomposites is enhanced by iodine doping to reach approximately 10 -6 S cm -1, but the value is much lower than that of the bulk crystals (10 1 S cm -1). © 2012 The Royal Society of Chemistry.
  • Masahiko Maekawa; Toshi Tominaga; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata; Susumu Kitagawa
    CRYSTENGCOMM 14 4 1345 - 1353 2012年 [査読有り]
     
    The reaction of [Cu(C2H4)(n)]NO3 with 4,4'-bipyrimidine (bpm) in Me2CO under C2H4 afforded a polymeric Cu(I)-bpm/C2H4 adduct [Cu-2(bpm)(C2H4)(NO3)(2)](n) (1) with an infinite 1-D zigzag chain structure. Similar reactions of [Cu(C2H4)(n)]ClO4 or [Cu(MeCN)(4)]BF4 with bpm in Me2CO under C2H4 afforded Cu(I)-bpm/C2H4 adducts {[Cu-3(bpm) (2)(C2H4) (2)](ClO4)(3)}(n) (2) and {[Cu-3(bpm)(2)(C2H4)(2)](BF4)(3)}(n) (3), respectively, which have an infinite 1-D zigzag ladder structure. It is interesting that two disordered ClO4- or BF4- anions are accommodated in the inside cavity of the ladder chains. In contrast, the reaction of [Cu(MeCN)(4)]BF4 with bpm in MeOH under C2H4 afforded a Cu(I)-bpm/C2H4 adduct {[Cu-4(bpm) (3)(C2H4) (3)(MeOH)](BF4)(4)center dot 2H(2)O center dot 3MeOH}(n) (4). Three Cu atoms are bridged by three bpm ligands to form a metallacalix[3] arene structure with three legs of C2H4. Furthermore, these metallacalix[3] arenes are linked through another Cu atom in the terminal N atom of bpm to produce a chiral 2-D sheet structure with space group P6(3). One BF4- anion is accommodated in the small triangular Cu-3 cavities, whereas three disordered BF4- anions are encapsulated in the large triangular Cu-3 cavities. In contrast to complex 4, [Cu(MeCN)(4)]BF4 was reacted with bpm in MeOH under Ar, and C2H4 gas was then bubbled into the resultant brown suspensions. The reaction solution was allowed to come to room temperature, and Cu(I)-bpm complex {[Cu-3(bpm)(3)](SiF6)(1.5)}(n) (5) was collected. The tetrahedral Cu atom is coordinated by two N atoms in the chelate site of bpm and two N atoms in the terminal sites of two other bpm ligands to form two racemic metallacalix[3] arene structures. It is noteworthy that these metallacalix[3] arenes are joined through the bpm ligands to afford a 3-D cage structure consisting of two right-handed and left-handed helix networks. One disordered SiF62- anion is accommodated in the inside cavity between two opposite metallacalix[3] arene structures. On the basis of these results, it has been concluded that BF4-, PF6-, ClO4- and SiF62- anions can serve as anion templates to self-assemble polymeric Cu(I) C2H4 adducts and a cage compound in complexes 2-5. The NO3- anion is ineffective as an anion template, as indicated by the higher coordination ability of the NO3- anion in complex 1. Additionally, solvent-dependent effects have been observed in the formation process: Me2CO can preferentially induce polymeric 1-D chain and 1-D ladder structures in complexes 1-3, whereas MeOH can produce 2-D sheet and 3-D cage structures by the linage of metallacalix[3]arene structures in complexes 4 and 5.
  • Masahiko Maekawa; Toshi Tominaga; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata; Susumu Kitagawa
    CRYSTENGCOMM 14 18 5955 - 5962 2012年 [査読有り]
     
    The reactions of Cu(I) ion with {BF4-, ClO4-, or PF6-} anions and 6,6'-dimethyl-4,4'-bipyrimidine (Me(2)bpm) under C2H4 or CO in MeOH preferentially afforded three 2D sheet Cu(I)-Me(2)bpm/{C2H4, CO} adducts [Cu-4(Me(2)bpm)(3)(C2H4)(3)(MeCN)](BF4)(4)center dot 0.33MeOH}(n) (2), {[Cu-4(Me(2)bpm)(3)(C2H4)(3)(MeOH)(0.33)](ClO4)(4)}(n) (3), and {[Cu-4(Me(2)bpm)(3)(CO)(3)(MeCN)](PF6)(4)center dot 0.33MeCN}(n) (4), whereas the similar reaction of Cu(I) ion with a BF4- anion and Me(2)bpm under CO in MeOH gave the metallamacrocyclic tetranuclear Cu(I)-Me(2)bpm/CO adduct [Cu-4(Me(2)bpm)(4)(CO)(4)](BF4)(4)center dot 4MeOH (5). In Cu(I)-Me(2)bpm/{C2H4, CO} adducts 2-4, it should be noted that the metallacalix[3]arene structures of the [Cu-3(Me(2)bpm)(3)](3+) framework are linked through another Cu atom with MeCN (2 and 4) or MeOH (3) to produce a chiral 2D sheet structure with small Cu-3 and large Cu-9 cavities. In the small triangular Cu-3 cavities, one MeOH (2) or MeCN (4) molecule is encapsulated in complexes 2 and 4, whereas these Cu-3 cavities are empty in complex 3. In the large Cu-9 cavities, one anion (X = BF4- (2), ClO4- (3) or PF6- (4)) is surrounding by six Me groups of three Me(2)bpm on the upside and three anions (X) are functionally accommodated on the downside for complexes 2-4, respectively. In the Cu(I)-Me(2)bpm/CO adduct 5, two of the four BF4- anions are accommodated in the upper and lower cavities of the [Cu-4(Me(2)bpm)(4)] framework. We demonstrated that the metallamacrocyclic and polymeric 2D sheet Cu(I)-Me(2)bpm/{C2H4, CO} adducts can be reasonably self-assembled under the direction of anions and solvents.
  • Takayoshi Kuroda-Sowa; Kana Kimura; Jun Kawasaki; Takashi Okubo; Masahiko Maekawa
    POLYHEDRON 30 18 3189 - 3192 2011年11月 [査読有り]
     
    The preparation and magnetic properties of two Fe(II) Schiff-base complexes, [Fe(qnal-12)(2)]center dot 2C(6)H(6) (1) and [Fe(Hqsalc)(2)] (2), (Hqnal-12 = N-(8'-quinolyl)-1-hydroxy-2-naphthaldimine, H(2)qsalc = 4-hydroxy-3-[(8-quinolinylimino)methyl][benzoic acid) are reported. X-ray single crystal structure analysis of 1 reveals that an Fe(II) ion is coordinated by two qnal-12 ligands in a meridional fashion. Molecular packing of 1 shows that a qnal-12 interacts with neighboring two qnal-12's through it-it interactions, which results in the formation of one-dimensional chain. Although the magnetic property of 1 shows a high-spin state at all the temperature range measured, the chi T-T plot of 2 shows abrupt spin crossover behavior with a wide hysteresis of 21 K, probably due to the hydrogen-bond network originated by carboxyl groups. (C) 2011 Elsevier Ltd. All rights reserved.
  • Kyung Ho Kim; Takashi Ueta; Takashi Okubo; Shinya Hayami; Haruho Anma; Kazuya Kato; Tetsuya Shimizu; Jyunji Fujimori; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    CHEMISTRY LETTERS 40 10 1184 - 1186 2011年10月 [査読有り]
     
    A novel mixed-valence Cu(I)-Cu(II) coordination polymer with an infinite one-dimensional (1-D) structure, [(Cu4CuI4)-Cu-I-I-II(Mor-dtc)(2)(CH3CN)(2)](n) (Mor-dtc(-): morpholine dithiocarbamate), was prepared and structurally characterized by X-ray diffraction. This complex consists of a mononuclear copper(II) unit of [Cu-II(Mor-dtc)(2)] and a tetranuclear Cu(I) unit of [Cu4I4(CH3CN)(2)]. It also shows semiconductive behaviors with a relatively small activation energy, which was revealed by impedance analysis.
  • Takashi Okubo; Hiroyasu Kuwamoto; Kyung Ho Kim; Shinya Hayami; Akihito Yamano; Motoo Shiro; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    INORGANIC CHEMISTRY 50 7 2708 - 2710 2011年04月 [査読有り]
     
    The reaction of Cu(Hm-dtc)(2), Br-2, and CuBr2 yielded a new mixed-valence octanuclear Cu-I/Cu-II/Cu-III cluster, encapsulating a Br anion in the center of the cluster cage. The octanuclear cluster units form a 1D assemblage, which induces intervalence charge-transfer transitions from Cu-II ions to Cu-III ions between the clusters.
  • Takashi Okubo; Naoya Tanaka; Kyung Ho Kim; Haruho Anma; Shu Seki; Akinori Saeki; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    DALTON TRANSACTIONS 40 10 2218 - 2224 2011年 [査読有り]
     
    A novel mixed-valence Cu(I)-Cu(II) coordination polymer having an infinite three-dimensional (3D) structure, {[(Cu4Cu2Br4)-Cu-I-Br-II(Pyr-dtc)(4)]center dot CHCl3}(n) (1) (Pyr-dtc(-) = pyrrolidine dithiocarbamate), has been prepared and structurally characterized via X-ray diffraction. This complex consists of 1D Cu(I)-Br chains and bridging mononuclear copper(II) units of Cu-II(Pyr-dtc)(2), which form an infinite 3D network. A magnetic study indicates that this complex includes copper(II) ions exhibiting a weak antiferromagnetic interaction (theta = -0.086 K) between the unpaired electrons of the copper(II) ions present in the diamagnetic Cu(I)-Br chains. The carrier transport properties of 1 are investigated using an impedance spectroscopy technique and flash-photolysis time-resolved microwave conductivity measurement (FP-TRMC). The impedance spectroscopy reveals that this complex exhibits intriguing semiconducting properties at a small activation energy (E-a = 0.29 eV (bulk)). The sum of the mobilities of the negative and positive carriers estimated via FP-TRMC is Sigma mu similar to 0.4 cm(2) V-1 s(-1).
  • Masahiko Maekawa; Kunihisa Sugimoto; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata
    POLYHEDRON 29 14 2807 - 2813 2010年09月 [査読有り]
     
    Three novel 1D Cu(I) coordination polymers [Cu4X4(pprd)(2)](n) (X = Cl(1), Br(2) and I(3): pprd = 4-(2-pyridyl)pyrimidine) were systematically synthesized by Cu(I) halides and the pprd ligand, and they have been characterized by X-ray, IR, and TG-DTA analyses. The molecular structure of complex 1 essentially resembles to that of complex 2. In complexes 1 and 2, four Cu(I) atoms are bridged by four Cl or Br anions to form an eight-membered Cu4X4 framework in the twist-chair form. Furthermore, the Cu4X4 frameworks are coordinated by the chelate and bridging sites of two pprd ligands to form a unique 1D two-stepped Cu(I) coordination polymer, in which two stairs are formed by the Cu4X4 core and two heteroaromatic planes of pprd. In the crystal packing structures, it is interesting that two heteroaromatic planes of pprd are stacking along the b-axis for complex 1 and the a-axis for complex 2. In contrast, four Cu(I) atoms in complex 3 are bridged by four I atoms to form a Cu4I4 stepped cubane tetramer. Additionally, the Cu4I4 stepped cubane cores are linked by the chelate and bridging sites of two pprd ligands to form an infinite 1D zigzag-chain Cu(l) coordination polymer. The thermal decomposition behaviors for Cu(I)-X/pprd complexes 1, 2 and 3 were determined by thermogravimetric analysis (TG-DTA). Although the thermal decomposition behaviors of complex 1 were unidentified, those of complexes 2 and 3 were assigned. The mass loss at the first stage of thermal decomposition for polymeric [Cu4X4(pprd)(2)](n) was identical to the formation of oligomeric [Cu4X4(pprd)] by the elimination of one pprd molecule. The mass loss at the next stage was decided to the formation of Cu4X4 by the elimination of another pprd molecule. (C) 2010 Elsevier Ltd. All rights reserved.
  • Kyung Ho Kim; Takashi Okubo; Naoya Tanaka; Naoto Mimura; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    CHEMISTRY LETTERS 39 7 792 - 793 2010年07月 [査読有り]
     
    The application of halide-bridged mixed-valence Cu(I)Cu(II) coordination polymers with hexamethylenedithiocarbamate (Hm-dtc) ligand as sensitizing materials for dye-sensitized solar cells (DSSCs) with poly(3,4-ethylenedioxythiophene) tetramethacrylate (PEDOT-TMA) counter electrode is novel. DSSCs having coordination polymers in comparison with a mononuclear Cu(Hm-dtc)(2) complex exhibited better power conversion efficiency because of the high photocurrent density.
  • Takashi Okubo; Naoya Tanaka; Kyung Ho Kim; Hironobu Yone; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    INORGANIC CHEMISTRY 49 8 3700 - 3702 2010年04月 [査読有り]
     
    New mixed-valence Cu-I-Cu-II coordination polymers with one-dimensional, infinite-chain structures, [(Cu2CuX2)-Cu-I-X-II(Hm-dtc)(2)(CH3-CN)(2)](n) [Hm-dtc(-) = hexamethylene dithiocarbamate, X = Br- (1), I- (2)], have been prepared and structurally characterized by X-ray diffraction. These complexes consist of a mononuclear copper(II) unit Cu-II(Hm-dtc)(2) and dinuclear copper(I) units Cu-2(I)(CH3CN)(2)X-2. Magnetic studies have revealed that these complexes have a relatively strong antiferromagnetic interaction [J = -26.9 cm(-1) (1) and J = -22.2 cm(-1) (2)] between the unpaired electrons of the Cu-II ions through the dinuclear copper(I) halide unit of (Cu2X2)-X-I in the chain. The electrical properties of 1 and 2 are investigated using an impedance spectroscopy technique, and it is revealed that these complexes exhibit intriguing semiconducting properties with small activation energies [E-a = 0.562 eV (1) and E-a = 0.479 eV (2)].
  • Shiki Yagai; Yujiro Nakano; Shu Seki; Atsushi Asano; Takashi Okubo; Takashi Isoshima; Takashi Karatsu; Akihide Kitamura; Yoshihiro Kikkawa
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 49 51 9990 - 9994 2010年 [査読有り]
  • Masahiko Maekawa; Toshi Tominaga; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata
    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY 28 4225 - 4231 2009年10月 [査読有り]
     
    Four novel Cu-I-Ph(2)bpm/C2H4 adducts [Cu(Ph(2)bpm)(C2H4)]X [X = BF4 (1a, 1b), ClO4 (2) and PF6 (3); Ph(2)bpm = 6,6'-diphenyl-4,4'-bipyrimidine] were prepared and they have been characterized by X-ray, H-1 NMR, IR and TG-DTA analyses. The molecular structures of Cu-I-Ph(2)bpm/C2H4 complexes la, 1b, 2 and 3 are essentially similar: the Cu atom is coordinated by two N atoms in the chelate site of Ph(2)bpm and the C=C bond of C2H4 in the trigonal-planar geometry. Interestingly, their crystal packing structures are much different from the connection manners of an intermolecular pi-pi stacking interaction and a C-H center dot center dot center dot N contact, resulting in the self-assembly of Cu-I-C2H4 adducts with a unique three-dimensional network structure. The X-ray, H-1 NMR, IR data support the assumption that the contribution of the larger Cu-I -> C2H4 pi back-donation bonding is induced by the electron-releasing phenyl group. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
  • Zhong Yu; Toshiyuki Shimizu; Toshi Tominaga; Takashi Okubo; Masahiko Maekawa; Takayoshi Kuroda-Sowa
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 82 10 1274 - 1276 2009年10月 [査読有り]
     
    Columnar assembly of dimeric Fell Schiff base complex based on twisted-overlap orientation of salophen platfonns exhibits ferromagnetic interactions at low temperature, which is ascribable to mu-phenoxy-bridged Fe ... Fe interactions and pi-pi interactions.
  • Atsuhiro Nabei; Takayoshi Kuroda-Sowa; Toshiyuki Shimizu; Takashi Okubo; Masahiko Maekawa; Megumu Munakata
    POLYHEDRON 28 9-10 1734 - 1739 2009年06月 [査読有り]
     
    The preparation and magnetic properties of three Fe(II)-bis-Schiff base complexes, [Fe(2)(L1)2(4,4'-bpy)]center dot MeOH (1), [Fe(L2)(EtOH)] (2) and [Fe(L3)(MeOH)] (3) (L1 =N,N'-bis(2-hydroxy-1-naphthaldehyde)-1,2-phenylenediimine; L2 = N,N'-bis(salicylidene)-1,2-phenylenediamine; L3 = N,N'-bis(5-Cl-salicylidene)-1,2-phenylenediamine; 4,4'-bpy = 4,4'-bipyridine) are reported. X-ray single crystal structure analyses for 1-3 reveal that 1 shows a dinuclear Fe(II)-bis-Schiff base complex bridged by 4,4'-bpy, while 2 and 3 show mononuclear structures. Molecular packing of 2 shows a uniform one-dimensional chain structure through hydrogen bonds and Fe center dot center dot center dot pi interaction and that of 3 indicates significant pi-pi interaction to form a dimmer structure. The chi T-T plots of 1-3 show all ferromagnetic interaction at low temperature. The origin of the ferromagnetic interaction observed in 2 is tentatively ascribed to the dimer formation through Fe center dot center dot center dot pi interaction at low temperature. (C) 2008 Elsevier Ltd. All rights reserved.
  • Zhong Yu; Takayoshi Kuroda-Sowa; Hiroaki Kume; Takashi Okubo; Masahiko Maekawa; Megumu Munakata
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 82 3 333 - 337 2009年03月 [査読有り]
     
    The spin-crossover (SCO) complex [Fe(qnal)(2)]center dot CH2Cl2 (1), (Hqnal: N-(8'-quinolyl)-2-hydroxy-1-naphthaldimine) with an N4O2 donor set, has been synthesized and characterized. Investigation of magnetic properties shows that the complex exhibits an abrupt and complete spin transition with a 5 K wide thermal hysteresis loop. The X-ray diffraction analysis of complex 1 reveals that the molecules are connected into a quasi one-dimensional chain through extended pi-pi interactions between aromatic rings of ligands. The effects of metal doping on SCO properties have been investigated in the mixed-metal system [Fe1-xMx(qnal)(2)]center dot CH2Cl2 (M = zinc(II) and nickel(II)). The results reveal that metal doping increases the gradual character of spin transition, and no marked differences found between zinc and nickel doping, which suggest the dominant effect of the doping-degree (concentration) rather than metal species on cooperativity. However, the metal doping shows different effects on critical temperature (T-1/2), where a more pronounced descending of T-1/2 is observed in response to increased Zn-doping than in Ni-doping, indicating the noticeable consequence of internal pressure due to the different radii of doping metal ions.
  • Zhong Yu; Takayoshi Kuroda-Sowa; Atsuhiro Nabei; Masahiko Maekawa; Takashi Okubo
    ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE 65 Pt 3 M257 - U298 2009年03月 [査読有り]
     
    In the title complex, [Co(C(26)H(20)N(2)O(4))(NCS)]center dot C(4)H(10)O center dot CH(2)Cl(2), the pentacoordinated Co(III) atom exhibits a distorted square-pyramidal geometry with an N,N',O,O' tetradentate Schiff base ligand in the basal plane and one thiocyanate ligand at the apical site. The diethyl ether molecule is located in a cavity provided by four O atoms of the ligand with weak C-H center dot center dot center dot O interactions, generating two short O center dot center dot center dot O contact distances [2.766 (3) and 2.745 (3) angstrom] between the diethyl ether molecule and the ligand. The crystal structure is stabilized by the weak C-H center dot center dot center dot O and C-H center dot center dot center dot N interactions and pi-pi interactions between the naphthyl ring system and the benzene ring [centroid-centroid distance = 3.657 (5) angstrom] and between the two naphthyl ring systems [centroid-centroid distance = 4.305 (2) angstrom].
  • Atsuhiro Nabei; Takayoshi Kuroda-Sowa; Takashi Okubo; Masahiko Maekawa; Megumu Munakata
    ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE 65 Pt 2 M188 - U669 2009年02月 [査読有り]
     
    The title compound, [Co(C(22)H(18)N(2)O(4))]center dot 2CH(2)Cl(2), was isolated from the reaction of N,N '(o-phenylene)bis(vanillalimine) (H(2)L) with Co(SCN)(2). The crystal structure contains a Co(II) ion surrounded by the L(2-) ligand in a slightly distorted square-planar fashion. Intermolecular C-H center dot center dot center dot O hydrogen-bonding contacts between the dichloromethane solvent molecules and the methoxy or carboxylate O atoms are observed in the crystal structure. The planar complex molecules stack through inversion related pi-pi interactions between the six-membered rings of the vanillalimine half ligands. The distance between centroids is 3.498 (2) angstrom and the perpendicular distance is 3.345 angstrom. A partial stacking is observed with a centroid-centroid distance of 3.830 (2) angstrom, a perpendicular distance of 3.350 angstrom and a slippage of 1.856 angstrom.
  • Masahiko Maekawa; Atsuhiro Nabei; Toshi Tominaga; Kunihisa Sugimoto; Toshie Minematsu; Takashi Okubo; Takayoshi Kuroda-Sowa; Megumu Munakata; Susumu Kitagawa
    DALTON TRANSACTIONS 3 415 - 417 2009年 [査読有り]
     
    Three novel Cu(I)-C2H4 adducts bearing 4-(2-pyridyl)-pyrimidine were self-assembled, and the roles of anion and solvent were proved in the formation process.
  • 黒田 孝義; Yu Zhong; 先崎 由蘭; 杉本 邦久; 前川 雅彦; 大久保 貴志; 速水 真也; 前田 米藏
    Chem. Lett. 37 12 1216 - 1217 日本化学会 2008年12月 
    Novel Fe-II complexes with N4O2 donor sets having, extended pi-conjugated aromatic rings, [Fe(qnal)(2)]center dot CH2Cl2 and [Fe(qnal)21, show abrupt spin transitions at 220 and 265 K, respectively. Both complexes show LIESST effects below 80 K.
  • Atsuhiro Nabei; Takayoshi Kuroda-Sowa; Takashi Okubo; Masahiko Maekawa; Megumu Munakata
    INORGANICA CHIMICA ACTA 361 12-13 3489 - 3493 2008年09月 [査読有り]
     
    Two new one-dimensional Fe(II)-bis-Schiff base complexes, [Fe(L1)(pyz)] center dot CH(2)Cl(2) (1) and [Fe(L2)(pyz)] center dot 2CH(2)Cl(2) (2) (H(2)L1 = bis(O-vanillin)-O-phenylenediimine, H(2)L2 = bis(O-vanillin)-2,3-naphthalenediimine, pyz = pyrazine) are reported with their crystal structures and magnetic property. Compound 1 shows a two-step SCO behavior while 2 shows HS at all the temperature range measured. Although the extension of aromatic moiety from benzene (L1) to naphthalene (L2) was introduced for the purpose of strengthening the cooperativity, it leads to the absence of SCO, due to the unanticipated pi-pi interaction, which leads to the longer Fe-N bond lengths and a weak ligand field around Fe(II) ion. (c) 2008 Elsevier B. V. All rights reserved.
  • Zhong Yu; Atsuhiro Nabei; Takafumi Izumi; Takashi Okubo; Takayoshi Kuroda-Sowa
    ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS 64 Pt 5 M209 - M212 2008年05月 [査読有り]
     
    4'-Cyanophenyl-2,2':6',2 ''- terpyridine (cptpy) was employed as an N, N', N ''- tridentate ligand to synthesize the compounds bis[ 4'-(4-cyanophenyl)-2,2': 6',2 ''- terpyridine] cobalt(II) bis(tetrafluoridoborate) nitromethane solvate, [Co(II)(C(22)H(14)N(4))(2)](BF(4))(2)center dot CH(3)NO(2), (I), and bis[4'-(4-cyanophenyl)- 2,2': 6',2 ''-terpyridine] cobalt(III) tris(tetrafluoridoborate) nitromethane sesquisolvate, [Co(III)(C(22)H(14)N(4))(2)](BF(4))(3)center dot 1.5CH(3)NO(2), (II). In both complexes, the cobalt ions occupy a distorted octahedral geometry with two cptpy ligands in a meridional configuration. A greater distortion from octahedral geometry is observed in (I), which indicates a different steric consequence of the constrained ligand bite on the Co(II) and Co(III) ions. The crystal structure of (I) features an interlocked sheet motif, which differs from the one- dimensional chain packing style present in (II). The lower dimensionality in (II) can be explained by the disturbance caused by the larger number of anions and solvent molecules involved in the crystal structure of (II). All atoms in (I) are on general positions, and the F atoms of one BF(4)(-) anion are disordered. In (II), one B atom is on an inversion center, necessitating disorder of the four attached F atoms, another B atom is on a twofold axis with ordered F atoms, and the C and N atoms of one nitromethane solvent molecule are on a twofold axis, causing disorder of the methyl H atoms. This relatively uncommon study of analogous Co(II) and Co(III) complexes provides a better understanding of the effects of different oxidation states on coordination geometry and crystal packing.
  • Shinya Hayami; Natsuko Motokawa; Aya Shuto; Naoji Masuhara; Yasuhiro Umebayashi; Yonezo Maeda; Osamu Sato; Katsuya Inoue; Ryo Kawajiri; Yui Kumura; Takashi Okubo; Tadaoki Mitani
    CHEMISTRY LETTERS 35 10 1114 - 1115 2006年10月 [査読有り]
     
    The dielectric changes of thermochromic compounds, [Cu(dieten)(2)]X-2 (X = BF4 and ClO4, dieten = NN-diethylethylenediamine), have been induced by the transformation between square-planar and distorted-square-planar.
  • Ryo Kawajiri; Takashi Okubo; Tadaoki Mitani
    POLYHEDRON 25 13 2650 - 2654 2006年09月 [査読有り]
     
    A new mixed-valence Cu(I)-Cu(II) octanuclear cluster, [(CuCuII)-Cu-I (n-Pr(2)dtc)Cl-2](2)[Cu-2(II)(n-Pr(2)dtc)(2)Cl-2](2) (1) (n-Pr(2)dtc(-) = di-n-propyldithiocarbamate) with a dithiocarbamate derivative has been synthesized and structurally characterized. Complex I consists of a mixed-valence Cu(I)-Cu(II) tetranuclear unit and two chloride-bridged Cu(II) dinuclear units. The octanuclear cluster forms an infinite one-dimensional assembly by weak Cu center dot center dot center dot Cl and Cu center dot center dot center dot S coordination bonds between the chloride bridged dinuclear units. The magnetic study indicates the existence of a strong antiferromagnetic interaction (J = -35.6 cm(-1)) between the copper ions of the chloride-bridged Cu(II) dinuclear unit, Cu-2(II) (n-Pr(2)dtc)(2)Cl-2. (C) 2006 Elsevier Ltd. All rights reserved.
  • 速水 真也; 本川 菜津子; 前田 米藏; 川尻 陵; 大久保 貴志; 三谷 忠興
    日本液晶学会討論会講演予稿集 2006 70 - 70 THE JAPANESE LIQUID CRYSTAL SOCIETY 2006年 
    金属錯体液晶の金属錯体部分にスピン転移錯体を組み込むと、スピン転移あるいは光誘起スピン転移に伴う液晶相転移の発現が可能となる。さらに長鎖アルキル基を有しているため、アルキル鎖の長さに依存した液晶特性および磁気特性などを詳細に検討することを目的に実験を行った。
  • T Okubo; R Maeda; M Kondo; T Mitani; S Kitagawa
    CHEMISTRY LETTERS 35 1 34 - 35 2006年01月 
    A new trisdithiolene vanadium(IV) complex has been synthesized and characterized. The enantionieric anion units, [V(dbddto)(3)](2-), are packed so closely that the sulfur-rich planar ligands stack to form a honeycomb sheet structure, resulting, in the creation of large cavities (12 x 5.5 angstrom) for guests. The magnetic susceptibilities show ail existence of antiferromagnetic interaction in spite of the large interatomic separation of the vanadium ions (V...V distance = 11.069 angstrom (av.)), associated with the interaction between the stacking ligand pathway in the honeycomb sheet.
  • T Okubo; R Kawajiri; T Mitani; T Shimoda
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 127 50 17598 - 17599 2005年12月 [査読有り]
  • S Noro; H Miyasaka; S Kitagawa; T Wada; T Okubo; M Yamashita; T Mitani
    INORGANIC CHEMISTRY 44 1 133 - 146 2005年01月 [査読有り]
     
    By utilizing the novel metalloligand L(Cu) [Cu(2,4-pydca)(2)](2-) (2,4-pydca (2-) = pyridine-2,4-dicarboxylate), which possesses two kinds of coordination groups, selective bond formation with the series of the first-period transition metal ions (Mn(II), Fe(II), Co(II), Cu(II), and Zn(II)) has been accomplished. Depending on the coordination mode of 4-carboxylate with Co(II), Cu(II), and Zn(II) ions, L(Cu) forms a one-dimensional (1-D) assembly with a repeating motif of [-M-O(2)C-(py)N-Cu-N(py)-CO(2)-]: {[ZnL(Cu)(H(2)O)(3)(DMF)](.)DMF}(n) (2), [ZnL(Cu)(H(2)O)(2)(MeOH)(2)](n) (3), and {[ML(Cu)(H(2)O)(4)](.)2H(2)O}(n) (M = Co (4), Cu (5), Zn (6)). The use of a terminal ligand of 2,2'-bipyridine (2,2'-bpy), in addition to the Cu(II) ion, gives a zigzag 1-D assembly with the similar repeating unit as 4-6: {[Cu(2,2'-bpy)L(Cu)](.)3H(2)O}(n) (9). On the other hand, for Mn(II) and Fe(II) ions, L(Cu) shows a 2-carboxylate bridging mode to form an another 1-D assembly with a repeating motif of [-M-O-C-O-Cu-O-C-O-]: [ML(Cu)(H(2)O)(4)](n) (M = Mn (7), Fe (8)). This selectivity is related to the strength of Lewis basicity and the electrostatic effect of L(Cu) and the Irving-Williams order on the present metal ions. According to their bridging modes, a variety of magnetic properties are obtained: 4, 5, and 9, which have the 4-carboxypyridinate bridge between magnetic centers, have weak antiferromagnetic interaction, whereas 7 and 8 with the carboxylate bridge between magnetic centers reveal 1-D ferromagnetic behavior (Cu(II)-M(II); M(II) = Mn(II), J/k(B) = 0.69 K for 7; M(II) = Fe(II), J/k(B) = 0.71 K for 8).
  • S Furukawa; T Okubo; S Masaoka; D Tanaka; HC Chang; S Kitagawa
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 44 18 2700 - 2704 2005年 [査読有り]
  • T. S. Kim; H. Murata; T. Okubo; T. Mitani
    Science and Technology of Advanced Materials 5 3 325 - 329 2004年05月 [査読有り]
     
    Aluminum (III) tris[2-(2-hydroxyphenyl)-5-phenyl-1,3-oxazole] (Alppo 3), has been synthesized as a new efficient blue electroluminescent (EL) material. Alppo3 provided good color purity, high luminance, and high efficiency of blue light-emission in an organic light-emitting device. The EL maximum wavelength is 420 nm and Commission Internationale de l'Eclairage coordinates are x=0.16, y=0.15 of blue color chromaticity. The luminance efficiency and the maximum luminance of Alppo3 device were 3lm/W at 6.05 mA/cm2 (345cd/m2) and 13,900cd/m2, respectively. © 2004 Published by Elsevier Ltd.
  • TS Kim; DH Kim; HJ Im; K Shimada; R Kawajiri; T Okubo; H Murata; T Mitani
    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 5 3 331 - 337 2004年05月 [査読有り]
     
    Improved lifetime with enhanced efficiency of an Alq(3) based OLED was realized by the co-evaporation of hexamethylbenzene (HMB). Two different solvated crystalline systems of Alq3, Alq(3)(C7H8)(1/2), Alq(3)(C2H5OH), were synthesized to investigate the effect of optically inactive materials on the emission properties of Alq(3). Clathrate solvents perturb the excited electronic states of Alq(3) so that the incorporated materials in OLEDs should be chemically and optically inactive to control polymorphs. HMB acts as a carrier blocker for both electrons and holes. However, Alq(3) may be stabilized from Joule heat if the Joule heat is efficiently consumed as the vibrational/rotational energy of HMB. Consequently, the self-quenching and the crystallization of Alq(3) are effectively suppressed by the HMB, resulting in prolonged operating time and enhanced efficiency for Alq(3)-OLEDs. (C) 2004 Published by Elsevier Ltd.
  • S Takaishi; Y Tobu; H Kitagawa; A Goto; T Shimizu; T Okubo; T Mitani; R Ikeda
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 126 6 1614 - 1615 2004年02月 [査読有り]
  • TS Kim; T Okubo; T Mitani
    CHEMISTRY OF MATERIALS 15 26 4949 - 4955 2003年12月 [査読有り]
     
    Oligomeric Zn(3)ppo(6), where ppo is 2-(2-hydroxyphenyl)-5-phenyl-1,3-oxazole, has been synthesized as a new blue-emitting material for organic light-emitting diodes (OLEDs). The electroluminescence maximum wavelength is 450 nm and the Commission Internationale de l'Eclairage (CIE) coordinates are x = 0.15, y = 0.11 for blue chromaticity. The luminance efficiency and the maximum luminance were about 1.3 lm/W at 6 V, 5.8 mA/cm(2) (139 cd/m(2)), and 8140 cd/m(2) at 11.4 V. Zn(3)ppo(6) shows two trimeric polymorphs and a monomeric structure at different sublimation temperatures.
  • Y. Morita; S. Maki; M. Hori; M. Ohmoto; E. Mochizuki; Y. Kai; H. Kitagawa; T. Mitani; K. Nakasuji
    Synthetic Metals 135-136 537 - 538 2003年04月 
    Novel tetrathiafulvalene (TTF) derivatives with mono-, bis- and tetrakis(4-hydroxylphenylthio) groups as hydrogen-bonding functionality, 1-3, were prepared from the lithiated TTF and a diphenyldisulfide derivative. Room-temperature resistivities of compressed pellets for 1-DDQ, 2-DDQ and 2-TCNQ were 1.1 × 109, 3.8 × 107 and 7.8 × 104 Ω·cm, respectively. In these complexes, alternated stacking type structures were inferred from the electronic spectra. © 2003 Elsevier Science B.V. All rights reserved.
  • Y. Morita; S. Maki; M. Ohmoto; H. Kitagawa; T. Okubo; T. Mitani; K. Nakasuji
    Synthetic Metals 135-136 541 - 542 2003年04月 
    New nucleobase-functionalized TTF derivatives, mono- and bis(2',3',5'-tri-tert-butyldimethylsiloxyladenosine-8-yl)-TTF, A-T and A-T-A (E/Z mixture), were prepared. Their oxidation potentials showed positive shift compared with that of TTF itself, implying weak electron-donating abilities. Alternated stacking type structures with a small degree of CT for A-T-TCNQ and with ionic natures for A-T-HCNAL, A-T-A-DDQ and A-T-A-HCNAL CT complexes were inferred from the electronic spectra. © 2003 Elsevier Science B.V. All rights reserved.
  • M. Ohmoto; S. Maki; Y. Morita; T. Kubo; H. Kitagawa; T. Okubo; T. Mitani; K. Nakasuji
    Synthetic Metals 133-134 337 - 339 2003年03月 
    We designed and prepared a TTF derivative with N1-n-butyl-substituted uracil (TnbU) which has the complementary double hydrogen-bonding (HB) sites and high solubility toward common organic solvents. The cyclic voltammogram of TnbU in DMF exhibited two-stage one-electron reversible oxidation behavior (E1 = -0.102 V E2 = +0.095 V versus Fc/Fc+), indicating slightly higher donating ability compared with TTF itself. The crystal structure of TnbU consists of the π-stacking dimer between TTF moieties and complementary double HB dimer between uracil moieties. The CT complex of TnbU with cyananilic acid (H2CNAL) exhibited alternated stacking type structure and complementary double HB between uracil moiety of TnbU and monoanion of H2CNAL, hydrogen cyananilate (HCNAL). © 2002 Elsevier Science B.V. All rights reserved.
  • Y Morita; S Maki; M Ohmoto; H Kitagawa; T Okubo; T Mitani; K Nakasuji
    ORGANIC LETTERS 4 13 2185 - 2188 2002年06月 [査読有り]
     
    [GRAPHICS] A novel TTF-based donor with a uracil moiety, TTF-(1-n-butyluracil-5-yl) (TnbU), was synthesized. Crystal structures of both TnbU and the charge-transfer complex of TnbU-hydrogen cyananilate possess complementary double hydrogen bonds through uracil moieties and pi-stacking dimer structures between TTF skeletons. Furthermore, the TnbU-TCNQ charge-transfer complex shows a high electrical conductivity underlying the partial charge-transfer accompanied by a hydrogen-bonding interaction, which was substantiated in terms of the measurements of the IR, electronic spectra, and conductivity.
  • ZY Yang; M Ebihara; T Kawamura; T Okubo; T Mitani
    INORGANICA CHIMICA ACTA 321 1-2 97 - 106 2001年09月 [査読有り]
     
    The reaction of 2,2-cis-[Rh,(acam)(4)(H2O)(2)]ClO4 (1) (Hacam = acetamide) with sodium halides in aqueous solution gave crystals of [Rh-2(acam)(4)X](n). mnH(2)O (X=Cl, Br, I). The composition of the products depended on the reaction temperature. The anhydrous compounds, [Rh-2(acam)(4)X](n) (X = Cl, 2; Br, 3; I, 4), were obtained at 40 degreesC, and the hydrated compounds, [Rh-2(acam)(4)Cl]. 7nH(2)O (2(.)7nH(2)O), [Rh-2(acam)(4)Br](n). 3nH(2)O (3(.)3nH(2)O) and [Rh-2(acam)(4)I](n). 2nH(2)O (4(.)2nH(2)O), were obtained at room temperature (15-25 degreesC. All of the compounds consist of infinite zigzag chains of (Rh-Rh-X-) units, which are supported by hydrogen bonds involving the NH(acam) and O(acam) atoms. The SOMO of the Rh-2(5+) units in the crystals can be assigned as the delta (RhRh)* MO from the Rh-L bond lengths, when compared with the corresponding Rh-2(4+) complex. The magnetic susceptibilities of 2, 3 and 4 are described by a I-D Heisenberg antiferromagnet with g = 2.003, 2.012, and 2.065, and J = - 8.6, - 7.9, and - 1.2 K, respectively. The ESR spectra of powdered crystals of 2, 3, and 4 were characteristic of rapid in-chain spin flip-flop exchange, most probably induced by the Heisenberg exchange interaction. (C) 2001 Elsevier Science B.V. All rights reserved.
  • hird-ordere nonlinear optical properties of a copper(I) trinuclear complex with D3h symmetrical radical ligand
    T. Okubo; S. Kitagawa; S. Masaoka; S. Furukawa; M. Kondo
    Nonlinear Optics 24 (num) 129 - 132 2000年12月 [査読有り]
  • H Matsuzaka; T Kamura; K Ariga; Y Watanabe; T Okubo; T Ishii; M Yamashita; M Kondo; S Kitagawa
    ORGANOMETALLICS 19 3 216 - 218 2000年02月 [査読有り]
     
    Reaction of [Cp*RhX(mu(2)-X)](2) (2a, X= Cl; 2b, X = Br) with (LiNH)(2)C10H6-1,8 gave the novel amido-bridged dinuclear Rh(III) complex [Cp*Rh{(mu(2)-NH)(2)C10H6- 1,8}(mu(2)-X)RhCp*]X (3a, X = Cl; 3b, X = Br), which further converted to the Rh(II) complex Cp*Rh{(mu(2)-NH)(2)C10H6-1,8}RhCp* (4) by Na/Hg reduction. Treatment of 4 with benzyl bromides produced 3b and the corresponding bz:benzyl derivatives, whereas protonation of 4 with CF3CO2H afforded [Cp*Rh{mu(2)-NH)(2)C10H6-1,8},{mu(2)-H)RhCp*]O2CCF3 (5). Complex 2a also reacted with 2 equiv of LiNHC6H4R-p to yield [Cp*Rh(mu(2)-NHC6H4R-p)(3)RhCp*]Cl (6 . Cl: 6a, R = Me; 6b, R = H; 6c, R = Cl).
  • Hiroyuki Matsuzaka; Koji Ichikawa; Tomohiro Ishioka; Haru Sato; Takashi Okubo; Tomohiko Ishii; Masahiro Yamashita; Mitsuru Kondo; Susumu Kitagawa
    JOURNAL OF ORGANOMETALLIC CHEMISTRY 596 1-2 121 - 129 2000年02月 [査読有り]
     
    Treatment of Cp*Ru(CO)(2)Cl (Cp* = eta(5)-C5Me5) with NaCo(CO)(4) produces the metal-metal bonded heterobimetallic complex Cp*Ru(CO)(2)(mu(2)-CO)Co(CO)(3) (2b). Substitution of the CO ligands by the Ph2PCH2PPh2 (dppm) leads to the isolation of Cp*Ru(mu(2)-CO)(2)(mu(2)-dppm)Co(CO)(2) (3) whereas that by (BuNC)-N-t gives Cp*Ru(CO)(CNBut)(mu(2)-CO)Co(CO)(3) (4). Stoichiometric head-to-tail dimerization of p-tolylacetylene at the bimetallic site of 2b proceeds to form the dinuclear metallacyclopentadiene complex Cp*(CO)Ru{eta(2):eta(4)-mu(2)-C(Tol)CHC(Tol)CH}Co(CO)(2) (5) in which two alkyne molecules are coupled to form a ruthenacyclopentadiene core which coordinates to the Co(CO), fragment. On the other hand, catalytic head-to-head coupling of methyl propiolate in the presence of 2b yields (E)-(MeO2C)CH=CH(C=CCO2Me) (6). The molecular structures of 2b, 3, 4, and 5 have been determined by X-ray crystallography. (C) 2000 Elsevier Science S.A. All rights reserved.
  • M. Kondo; K. Fujimoto; T. Okubo; A. Asami; S. Noro; S. Kitagawa; T. Ishii; H. Matsuzaka
    Chem. Lett. 4 291 - 292 1999年04月 [査読有り]
     
    New porous coordination polymer, {(H(2)dpds)(2)[V10O26(OH)(2)] . 10H(2)O}(n) (H(2)dpds = bis(4-pyridinium) disulfide), was synthesized and structurally characterized. X-ray analysis demonstrates that the decavanadate anions are doubly bridged by H(2)dpds ligands to provide a one-dimensional structure. This network affords channeling cavities with dimension of about 2 x 4 Angstrom along the c-axis.
  • Okubo T; Kitagawa S; Kondo M; Matsuzaka H; Ishii T
    Angewandte Chemie (International ed. in English) 38 7 931 - 933 1999年 [査読有り]
  • T. Okubo; T. Ohrui; M. Kondo; S. Kitagawa; H. Matsuzaka
    Synthetic Metals 102 1-3 1464 - 1465 1999年 [査読有り]
     
    A compound, [(CuI)2(TPTB)]n (TPTB = 1,2,4,5-tetra-isopropyl-thiobenzene) has been synthesized and characterized. The complex crystallizes in the monoclinic space group P21 with a = 8.709(3) angstrom, b = 18.056(2) angstrom, c = 8.755(2) angstrom, β = 96.16(2)°, V = 1368.7(5) angstrom3 and Z = 2. The complex contains one-dimensional infinite chain structure consisting of copper(I) ions, bridging bis-bidentate tetrathioether ligands and bridging iodide ions. The chains are connected by S...S contacts of the ligands, resulting in the formation of a two-dimensional network. The iodide-doping for the colorless powder sample give rise to the enhancement the conductivity (5.6 × 10-6 Scm-1).
  • M Kondo; T Okubo; A Asami; S Noro; T Yoshitomi; S Kitagawa; T Ishii; H Matsuzaka; K Seki
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 38 1-2 140 - 143 1999年 [査読有り]
  • T Okubo; M Kondo; S Kitagawa
    SYNTHETIC METALS 85 1-3 1661 - 1662 1997年02月 [査読有り]
     
    A title compound has been synthesized and characterized. The complex crystallizes in the monoclinic space group C2/c with a = 12.768(1)Angstrom, b = 7.5159(8)Angstrom, c = 13.271(1)Angstrom, beta = 123.591(4)degrees, V = 1060.8(2)Angstrom(3) and Z = 4. The complex consists of one-dimensional chains of copper(II) ions bridged by pyrazine-2,3-dicarboxylate. Each copper ion has a distorted octahedral coordination with N2O4 chromophor. The magnetic susceptibility data over a range of 2 - 300 K were fitted by using an Heisenberg antiferromagnet, H = 2J Sigma S-i . Si+1, with the parameters of J = -1.40 cm(-1), g = 2.14 and rho = 0.032.
  • T Okubo; M Kondo; S Kawata; S Kitagawa; A Miyazaki; T Enoki
    MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY SECTION A-MOLECULAR CRYSTALS AND LIQUID CRYSTALS 285 437 - 442 1996年 [査読有り]
     
    A title compound has been synthesized and characterized. The complex crystallizes in the orthorhombic space group Cmcm with a = 7.004(2) Angstrom, b = 12.748(2) Angstrom, c = 13.665(2) Angstrom, V = 1220.1(3) Angstrom(3) and Z = 4. The complex consists of two-dimensional square arrays of nickel(II) ions bridged by pzdc(2-) and pyz ligands. Each nickel ion has a slightly distorted octahedral coordination with N4O2 chromopher. The magnetic susceptibility data over a range of 2 - 300 K were fitted by using an Heisenberg antiferromagnet with a mean field approximation. The obtained J and zJ' values are -1.70 cm(-1) and -0.70 cm(-1), respectively.
  • S KITAGAWA; T OKUBO; S KAWATA; M KONDO; M KATADA; H KOBAYASHI
    INORGANIC CHEMISTRY 34 19 4790 - 4796 1995年09月 [査読有り]
     
    The new copper(II) coordination polymer [CU2(mu-ox)(2)(mu-pyz)(pyz)(2)](n) (1) (ox = oxalate; pyz = pyrazine) has been synthesized and characterized. 1 crystallizes in the triclinic space group P ($) over bar 1 with a = 10.578(4) Angstrom, b = 11.603(5) Angstrom, c = 8.027(4) Angstrom, alpha = 92.11(5)degrees, beta = 103.10(3)degrees, gamma = 76.32(4)degrees, V = 932.3(8) Angstrom(3), Z = 2, and chemical formula CU2C16N6O8H12. 1 shows an extended sheet structure of copper(II) ions bridged by oxalate anions and pyrazine. The repeating unit of (Cu-2(mu-ox)(2)(mu-pyz)(pyz)(2)) contains two types of 4 + 2 coordination environments with O4N2, which are characteristic of pyz coordination; one of the two copper atoms has only terminally coordinated pyz molecules while the other is linked by bridging pyz molecules. The Cu-ox-Cu-sequence displays as pleated ribbon, thus planes of Cu-ox-Cu form a boat conformation. In addition to the coordination bond linking, there is stack linking of pyz molecules whose column runs along the ribbon. The magnetic susceptibilities were measured to 2 K and analyzed in terms of an alternating-chain Heisenberg-exchange model (H = -2J Sigma(i=1)(n/2) [S-2i. S-2i-1 + alpha S-2i. S-2i+1]) to yield J = -20.4 cm(-1) and alpha = 0.85. The alternate arrangement of the copper geometries along a ribbon leads to that of the magnetic orbitals. This well explains the value of J smaller than that of [Cu(ox)](n) without apical ligands and comparable to that of [CU(ox)(NH3)(2)](n). The density functional MO calculation and EHMO band calculations were carried out to delineate the electronic structure and the role of pyz molecules in the extended structure.

講演・口頭発表等

  • Crystal structures and carrier transport properties of coordination polymers including copper(I) halides  [招待講演]
    大久保貴志
    China-Japan Symposium of Functional Coordination Chemistry 2019年04月 口頭発表(招待・特別)
  • Conducting Porperties and Application to Organic Solar Cells of Coordination Polymers Including Copper(I) Halides  [通常講演]
    大久保貴志
    Advances in Organic and Hybrid Electronic Materials 2018 (AOHM19) 2019年03月 口頭発表(一般)
  • Crystal Structures and Carrier Transport Properties of Coordination Polymers Including Copper(I) Halides  [招待講演]
    大久保貴志
    2018 Nankai International Symposium on Advanced Materials 2018年11月 口頭発表(基調)
  • Conducting Properties and Application to Organic Solar Cells of Coordination Polymers Consisting of Copper(I) Halides and Hexaazatriphenylene Derivatives  [招待講演]
    T. Okubo; W. Genno; M. Okita; S. Shimakawa; K. Nakamura; K. Himoto; M. Maekawa; T. Kuroda-Sowa
    International Conference on Coordination Chemistry, 2018, Sendai, Japan 2018年08月 口頭発表(招待・特別)
  • Development of bulk hetero-junction organic thin-film photovoltaic cells  [通常講演]
    Takashi OKUBO; Koki TANISHIMA; Kento HIMOTO; Toshiya HORII; Wataru Genno; Masahiko MAEKAWA; Takayoshi KURODA-SOWA
    International Symposium on Chemistry for Solar Energy Applications 2017 2017年08月 口頭発表(一般)
  • 新規なヘテロ金属Ag(I)-Ir(III)ヒドリド配位高分子の合成および構造  [通常講演]
    前川 雅彦; 久保 有希実; 大久保 貴志; 黒田 孝義; 宗像 惠
    第63回錯体化学討論会 2013年11月 那覇 (琉球大学千原キャンパス) 第63回錯体化学討論会
     
    3種の2,2'-ビピリジン類縁配位子(L)を用いて、配位不飽和なIr(III)-ヒドリド錯体[Ir(H)2(PPh3)2(L)]BF4を合成し、さらにCF3COOAgと反応させることにより、3種の新規なヘテロ金属Ag(I)-Ir(III)ヒドリド配位高分子を合成し、そのX線構造および性質を明らかにした。
  • Ir(III)ヒドリド錯体を連結した新規な一次元Ir(III)-Ag(I)配位高分子の合成および構造  [通常講演]
    前川 雅彦; 久保 有希実; 大久保 貴志; 黒田 孝義; 宗像 惠
    第62回錯体化学討論会 2012年09月 富山(富山大学五福キャンパス) 第62回錯体化学討論会
     
    [Ir(H)2(PPh3)2(Me2CO)2]BF4と4,4'-ビキナゾリン(biqz)を用いて、錯体配位子として配位不飽和なIr(III)-ヒドリド錯体[Ir(H)2(PPh3)2(biqz)]BF4を合成し、さらにCF3COOAgと反応させることにより、新規な一次元Ag(I)-Ir(III)-biqz混合金属配位高分子を合成し、そのX線構造および性質を明らかにした。
  • 多座窒素配位子を有する新規なCu(I)-エチレン錯体の合成,構造および性質  [通常講演]
    前川 雅彦; 南野 愛; 大久保 貴志; 黒田 孝義; 宗像 惠
    第62回錯体化学討論会 2012年09月 富山(富山大学五福キャンパス) 第62回錯体化学討論会
     
    C2H4雰囲気下,アセトン溶媒中,[Cu(MeCN)4]BF4と4,6-ビス(2-ピリジル)-ピリミジン (bppym)を反応させたところ,[Cu2(bppym)(C2H4)2](BF4)2?Me_2CO (1)が得られた。同様に[Cu(C2H4)n]ClO4とbppymを反応させたところ,[Cu2(bppym)(C2H4)2](ClO4)2?Me2CO (2)が得られた。またC2H4雰囲気下,メタノール溶媒中,[Cu(MeCN)4]BF4と4,6-ビス(2-ピリジル)-ピラジン (bppz)を反応させたところ,[Cu2(bppz)(C2H4)2](BF4)2?MeOH (3)が得られた。X線構造解析の結果,錯体1, 2および3はいずれも新規な二核Cu(I)-エチレン錯体であることが明らかとなった。
  • First Cu(I) coordination polymers of 4,4’-biquinazoline and the C2H4 adduct  [通常講演]
    前川 雅彦; 南野 愛; 大久保 貴志; 黒田 孝義; 宗像 惠
    The 40th International Conference on Coordination Chemistry (ICCC40) 2012年09月 Valencia, Spain The 40th International Conference on Coordination Chemistry (ICCC40)
  • Structural controls of Cu(I) C2H4 coordination polymers of 4,4’-bipyrimidine  [通常講演]
    前川 雅彦; 大久保 貴志; 黒田 孝義; 宗像 惠; 財; 高輝度光科学研究センター(JASRI; 京都大学大学院工学研究科
    The 40th International Conference on Coordination Chemistry (ICCC40) 2012年09月 Valencia, Spain The 40th International Conference on Coordination Chemistry (ICCC40)
  • Novel mono- and dinuclear Iridium(III) hydride complexes of 2,2’-bipyrimidine  [通常講演]
    前川 雅彦; 久保 有希実; 大久保 貴志; 黒田 孝義; 宗像 惠
    The 40th International Conference on Coordination Chemistry (ICCC40) 2012年09月 Valencia, Spain The 40th International Conference on Coordination Chemistry (ICCC40)
  • 多座窒素配位子を有する新規なIr(III)ヒドリド錯体の合成,構造および性質  [通常講演]
    前川 雅彦; 久保 有希実; 大久保 貴志; 黒田 孝義; 宗像 惠
    日本化学会第92春季年会 2012年03月 慶應大学日吉キャンパス(横浜) 日本化学会第92春季年会
     
    Ar雰囲気下,CHCl3溶液中,[Ir(H)2(PPh3)2(Me2CO)2]X(X=BF4, PF6)と様々なビピリミジン系配位子を反応させ,5種の新規なIr(III)ヒドリド錯体を単離することに成功し,その構造ならびに性質をX線構造解析,IR, TG-DTA, 固体UV-VIS, 1H NMR法より特徴付けた。例えば,2,2'-ビピリミジン (bpym)を用いた場合,合成溶媒選択的に単核Irヒドリド錯体[Ir(H)2(PPh3)2(bpym)]BF4および二核Irヒドリド錯体[Ir2(H)4(PPh3)4(bpym)](BF4)2が生成することが明らかとなった。
  • 多座窒素配位子を用いた新規なCu(I)-エチレン錯体の合成,構造および性質  [通常講演]
    前川 雅彦; 南野 愛; 大久保 貴志; 黒田 孝義; 宗像 惠
    日本化学会第92春季年会 2012年03月 慶應大学日吉キャンパス(横浜) 日本化学会第92春季年会
     
    C2H4雰囲気下,アセトン溶媒中,[Cu(MeCN)4]BF4と4,6-ビス(2-ピリジル)-ピリミジン (bppym)を反応させたところ,[Cu2(bppym)(C2H4)2](BF4)2?Me2CO (1)が得られた。同様に[Cu(C2H4)n]ClO4とbppymを反応させたところ,[Cu2(bppym)(C2H4)2](ClO4)2?Me2CO (2)が得られた。X線構造解析の結果,錯体1および2はいずれも新規な二核Cu(I)-エチレン錯体であることが明らかとなった。
  • 3,6-ビス(2-ピリジル)-1,2,4,5-テトラジンを配位子とする様々なCu(I)-エチレン錯体の合成および構造  [通常講演]
    前川 雅彦; 宮崎 武志; 大久保 貴志; 黒田 孝義; 宗像 惠
    日本化学会第92春季年会 2012年03月 慶應大学日吉キャンパス(横浜) 日本化学会第92春季年会
     
    C2H4雰囲気下,Me2CO中,Cu(ClO4)2,金属銅および3,6-ビス(2-ピリジル)-1,2,4,5-テトラジン(bptz)を反応させると,3種の新規なCu(I)-bptz/C2H4錯体および4核Cu(I)-bptz錯体が生成することを見出し,その構造および性質を明らかにした。特にテトラジン環がアニオンラジカル化した{[Cu2(bptz)(C2H4)2]ClO4}2ならびにテトラジン環が大きく歪んだ[Cu2(bptz)(C2H4)2](ClO4)2は興味が持たれる。
  • ビピリミジン系多座窒素配位子を有する新規なイリジウム(III)ヒドリド錯体の合成と構造化学的特徴付け  [通常講演]
    前川 雅彦; 久保 有希実; 大久保 貴志; 宗像 惠; 黒田 孝義
    第61回錯体化学討論会 2011年09月 岡山(岡山理科大学) 第61回錯体化学討論会
     
    Ar下、CHCl3中、[Ir(H)2(PPh3)2(Me2CO)2]BF4と4-(2-ピリジル)ピリミジン(pprd)を反応させ、新規な単核錯体[Ir(H)2(pprd)(PPh3)2]BF4を合成した。同様に2,2'-ビピリミジン(bpym)を反応させると、単核錯体[Ir(H)2(bpym)(PPh3)2]BF4および二核錯体[Ir2(H)4(bpym)(PPh3)4](BF4)2が生成することを見出した。いずれの錯体も溶液内において環電流効果に基づく特徴的な磁気異方性シフトが観測された。
  • アニオンおよび溶媒に導かれた4,4'-ビピリミジン類を配位子とする新規なCu(I)配位高分子の自己組織化  [通常講演]
    前川 雅彦; 南野 愛; 大久保 貴志; 宗像 惠; 黒田 孝義
    第61回錯体化学討論会 2011年09月 岡山(岡山理科大学) 第61回錯体化学討論会
     
    C2H4雰囲気下、MeOH中、[Cu(CH3CN)4]X (X=BF4, PF6)と4,4'-ビキナゾリン(biqz)を反応させると、biqzのキレート部位と橋かけ部位がCu(I)イオンに配位し、Cu2C6N6骨格からなる14員環構造が繋げられた新規なCu(I)ポリマー錯体{[Cu4(biqz)2(CH3CN)4(MeOH)4(BF4)4}n (1)および{[Cu4(biqz)2(CH3CN)8](PF6)4}n(2)が自己組織化されることを見出した。同様に、Me2CO中において[Cu(C2H4)n]ClO4とbiqzを反応させると、錯体1および2とは異なり、アニオンおよび溶媒選択的に、一次元ジグザグ鎖構造を有するCu(I)エチレン付加体{[Cu2(biqz)(C2H4)2](ClO4)2}n(3)が自己組織化されることを見出した。
  • アニオンラジカルを配位子とする始めてのCu(I)-エチレン錯体の合成、構造およびキャタクタリゼーション  [通常講演]
    前川 雅彦; 宮崎 武志; 大久保 貴志; 宗像 惠; 黒田 孝義
    第61回錯体化学討論会 2011年09月 岡山(岡山理科大学) 第61回錯体化学討論会
     
    C2H4下、Me2CO中、Cu(ClO4)2、金属Cuおよび3,6-ビス(2-ピリジル)-1,2,4,5-テトラジン(bptz)を反応させると、アニオンラジカルを配位子とする始めての二核Cu(I)-C2H4錯体{[Cu2(bptz)(C2H4)2]ClO4}2が生成することを見出し、そのX線構造および性質を明らかにした。あわせてbtpzが極めて珍しいcis形構造を取った二核錯体[Cu2(bptz)(C2H4)2](ClO4)2が生成することを見出した。
  • ビピリミジン系架橋配位子を用いた新規なIr(III)ヒドリド錯体の合成および構造  [通常講演]
    前川 雅彦; 久保 有希実; 大久保 貴志; 黒田 孝義; 宗像 惠
    日本化学会第91春季年会(2011) 2011年03月 神奈川大学横浜キャンパス 日本化学会第91春季年会(2011)
     
    Ar雰囲気下、CHCl3中、[Ir(H)2(PPh3)2(Me2CO)2]X (X=BF4, PF6)と4-(2-ピリジル)ピリミジン(pprd)および4,4’-ビキナゾリン(biqz)を反応させたところ、[Ir(H)2(PPh3)2(pprd)]BF4 (1)および[Ir(H)2(PPh3)2(biqz)]PF6 (2)が得られた。X線構造解析の結果、錯体1および2はIr原子にヒドリド、PPh3および窒素配位子が配位した単核錯体であることがわかった。溶液中において環電流効果に伴う特徴的な1H NMRシフトを観測した。
  • ビピリミジン系配位子により構築された新規なCu(I)配位高分子の合成、構造および性質  [通常講演]
    前川 雅彦; 南野 愛; 大久保 貴志; 黒田 孝義; 宗像 惠
    日本化学会第91春季年会(2011) 2011年03月 神奈川大学横浜キャンパス 日本化学会第91春季年会(2011)
     
    C2H4雰囲気下、メタノール中、[Cu(CH3CN)4]X (X=BF4, PF6)と4,4'-ビキナゾリン(biqz)を反応させたところ、{[Cu4(biqz)2(CH3CN)4(MeOH)4](BF4)4}n (1)および{[Cu4(biqz)2(CH3CN)8](PF6)4}n (2)が得られた。X線構造解析の結果、錯体1および2はいずれもbiqzのキレート部位と橋架け部位がCu(I)イオンに配位し、Cu2C6N6骨格からなる14員環構造が繋げられた新規なCu(I)ポリマー錯体であることがわかった。
  • テトラジンアニオンラジカルを有する新規なCu(I)-エチレン錯体の合成および構造  [通常講演]
    前川 雅彦; 宮崎 武志; 大久保 貴志; 黒田 孝義; 宗像 惠
    日本化学会第91春季年会(2011) 2011年03月 神奈川大学横浜キャンパス 日本化学会第91春季年会(2011)
     
    C2H4雰囲気下、Me2CO中、Cu(ClO4)2、金属銅および3,6-ビス(2-ピリジル)-1,2,4,5-テトラジン(bptz)を反応させることにより、テトラジンアニオンラジカルを有する二核Cu(I)-エチレン錯体が生成することを見出し、その構造および性質を明らかにした。あわせて、ラジカル化していないbptzが配位した2種類の二核Cu(I)-エチレン錯体が生成することを見出した。
  • Novel Cu(I) metallamacrocycles toward structurally and functionally new inorganic anion receptors  [通常講演]
    前川 雅彦; 大久保 貴志; 黒田 孝義; 宗像 惠; 京都大学大学院工学研究科
    The 2010 International Chemical Congress of Pacific Basin Societies (Pacifichem 2010) 2010年12月 Honolulu, Hawaii, USA The 2010 International Chemical Congress of Pacific Basin Societies (Pacifichem 2010)
  • チオシアン酸鉄と架橋配位子bpbによって構築されたフレームワーク構造を有する錯体の構造と物性  [通常講演]
    増田 隆之; 鈴木 詩織; 大久保 貴志; 前川 雅彦; 黒田 孝義
    第60回錯体化学討論会 2010年09月 大阪 第60回錯体化学討論会
  • CN架橋基を有するCoシッフ塩基錯体の合成と構造  [通常講演]
    川崎 惇; 大久保 貴志; 前川 雅彦; 黒田 孝義
    第60回錯体化学討論会 2010年09月 大阪 第60回錯体化学討論会
  • 平面性Schiff塩基配位子を有するFe錯体の合成・構造とSCO挙動  [通常講演]
    木村 佳樹; 川崎 惇; 大久保 貴志; 前川 雅彦; 黒田 孝義
    第60回錯体化学討論会 2010年09月 大阪 第60回錯体化学討論会
  • クロラニル酸を架橋基とした新規な一次元鎖鉄錯体の合成と磁気的性質  [通常講演]
    諸富 匠; 前川 雅彦; 大久保 貴志; 黒田 孝義
    第60回錯体化学討論会 2010年09月 大阪 第60回錯体化学討論会
  • テトラジンアニオンラジカルを有する新規なCu(I)-エチレン錯体の合成と構造  [通常講演]
    前川 雅彦; 宮崎武志; 大久保 貴志; 黒田 孝義; 宗像 惠
    第60回錯体化学討論会 2010年09月 大阪 (大阪国際交流センター) 第60回錯体化学討論会
     
    エチレン雰囲気下、Me2CO中、Cu(ClO4)2、金属銅および3,6-ビス(2-ピリジル)-1,2,4,5-テトラジン(bptz)を反応させたところ、テトラジンアニオンラジカルを有する二核Cu(I)- -bptz/C2H4錯体が生成することを見出し、その構造および性質を明らかにした。あせてシス形配置を有する二核Cu(I)-bptz/C2H4錯体の単離・構造解析も明らかにした。
  • カルボキシル基を有するFe(II)SCO錯体における水素結合の効果  [通常講演]
    木村 佳樹; 大久保 貴志; 前川 雅彦; 黒田 孝義
    日本化学会第90春季年会 2010年03月 大阪 日本化学会第90春季年会
  • 平面性コバルト(II)Salphen系錯体の積層構造と物性  [通常講演]
    川崎 惇; 大久保 貴志; 前川 雅彦; 黒田 孝義
    日本化学会第90春季年会 2010年03月 大阪 日本化学会第90春季年会
  • チオシアン酸コバルトとbpb架橋配位子により構築された3次元相互貫入フレームワーク錯体の構造とゲスト分子吸脱着特性  [通常講演]
    増田 隆之; 大島 有紀子; 富永 登志; 大久保 貴志; 前川 雅彦; 黒田 孝義
    日本化学会第90春季年会 2010年03月 大阪 日本化学会第90春季年会
  • テトラジンアニオンラジカルを有する新規なCu(I)-エチレン錯体の合成および構造  [通常講演]
    前川 雅彦; 宮崎 武志; 大久保 貴志; 黒田 孝義; 宗像 惠
    日本化学会第90回春季年会 2010年03月 東大阪(近畿大学本部キャンパス) 日本化学会第90回春季年会
     
    C2H4雰囲気下、アセトン中、Cu(ClO4)2、金属銅および3,6-ビス(2-ピリジル)-1,2,4,5-テトラジン (bptz)を反応させたところ、2種類の針状結晶{[Cu2(bptz)(C2H4)2]ClO4}2 (1)および板状結晶[Cu2(bptz)(C2H4)2](ClO4)2 (2)が得られた。X線構造解析の結果、bptzが還元されてテトラジンアニオンラジカルを生成し、錯体1はアニオンラジカルを配位子とする始めての二核Cu(I)-エチレン錯体である。
  • Novel Cu(I) Ethylene Complexes Three?Dimensionally Self?Assembled by an Intermolecular π?π Stacking Interaction and a C?H???N Contact  [通常講演]
    前川 雅彦; 富永 登志; 大久保 貴志; 黒田 孝義; 宗像 惠
    The second Asian Conference on Coordination Chemistry (2nd ACCC) 2009年11月 Nanjing, China The second Asian Conference on Coordination Chemistry (2nd ACCC)
  • Synthesis of Cu(I) and Ag(I) Metallamacrocycles as Structurally and Functionally New Inorganic Anion Receptors  [通常講演]
    前川 雅彦; 大久保 貴志; 黒田 孝義; 宗像 惠; 北川 進
    The second Asian Conference on Coordination Chemistry (2nd ACCC) 2009年11月 Nanjing, China The second Asian Conference on Coordination Chemistry (2nd ACCC)
  • N2O型Schiff塩基配位子による鉄錯体の合成と物性  [通常講演]
    木村 佳樹; 前川 雅彦; 大久保 貴志; 黒田 孝義
    第59回錯体化学討論会 2009年09月 長崎 第59回錯体化学討論会
  • Salphen系配位子を用いた平面性コバルト(II)錯体の構造と物性  [通常講演]
    川崎 惇; 前川 雅彦; 大久保 貴志; 黒田 孝義
    第59回錯体化学討論会 2009年09月 長崎 第59回錯体化学討論会
  • S字型架橋配位子を用いた多核鉄錯体の合成  [通常講演]
    諸富 匠; 大久保 貴志; 前川 雅彦; 黒田 孝義
    第59回錯体化学討論会 2009年09月 長崎 第59回錯体化学討論会
  • 架橋能を有するterpy系Co(II)及びCu(II)錯体による配位高分子の合成と物性  [通常講演]
    泉 貴文; 富永 登志; 前川 雅彦; 大久保 貴志; 黒田 孝義
    第59回錯体化学討論会 2009年09月 長崎 第59回錯体化学討論会
  • N4O2型配位環境を有する一次元鎖Fe(II)スピンクロスオーバー錯体の合成と構造  [通常講演]
    清水 俊行; 富永 登志; 鍋井 淳宏; 前川 雅彦; 大久保 貴志; 黒田 孝義
    第59回錯体化学討論会 2009年09月 長崎 第59回錯体化学討論会
  • 4,4'-ビピリミジン類を配位子とする新規なCu(I)配位高分子の合成と構造  [通常講演]
    前川 雅彦; 富永 登志; 大久保 貴志; 黒田 孝義; 宗像 惠; 杉本 邦久; 北川 進
    第59回錯体化学討論会 2009年09月 長崎(長崎大学文京キャンパス) 第59回錯体化学討論会
     
    Ar/C2H4雰囲気下、MeOH中、[Cu(CH3CN)4]BF4と4,4'-ビピリミジン (bpm)を反応させたところ、そのゲージ内にガラス管由来のSiF6アニオンを捕捉した3次元Cu(I)-bpm配位高分子が自己集積化した。またC2H4雰囲気下、同様の反応を試みたところ、その空孔内にBF4アニオンを捕捉したメタラマクロサイクルが連結された2次元Cu(I)-bpm-C2H4付加体が生成した。
  • カルボキシル基を有するN2O型Schiff Base配位子によるFe錯体の合成とその多核化  [通常講演]
    木村 佳樹; 玉浦 裕貴; 大久保 貴志; 前川 雅彦; 黒田 孝義
    日本化学会第89春季年会 2009年03月 船橋 日本化学会第89春季年会
  • 7,7,8,8-tetracyanoquinodimethane (TCNQ) 由来のイソシアニド配位を有するシッフ塩基コバルト錯体の合成  [通常講演]
    川崎 惇; Yu Zhong; 鍋井 淳宏; 大久保 貴志; 前川 雅彦; 黒田 孝義
    日本化学会第89春季年会 2009年03月 船橋 日本化学会第89春季年会
  • bis-Schiff塩基配位子を有する一次元鎖Fe錯体の構造と磁気特性  [通常講演]
    鍋井 淳宏; 大久保 貴志; 前川 雅彦; 宗像 惠; 黒田 孝義
    日本化学会第89春季年会 2009年03月 船橋 日本化学会第89春季年会
  • 強磁性的相互作用を示すbis-Schiff塩基配位子を有 した新規Fe(II)錯体の合成及び構造  [通常講演]
    清水 俊行; 鍋井 淳宏; 前川 雅彦; 大久保 貴志; 黒田 孝義
    日本化学会第89春季年会 2009年03月 船橋 日本化学会第89春季年会
  • アニオンテンプレート法による新規なCu(I)メタラマクロサイクリック-カルボニル付加体の自己集積化  [通常講演]
    前川 雅彦; 富永 登志; 鍋井 淳宏; 大久保 貴志; 黒田 孝義; 宗像 惠; 北川 進
    日本化学会第89春季年会 2009年03月 船橋 日本化学会第89春季年会
     
    CO雰囲気下、[Cu(CH3CN)4]BF4と6,6'-ジメチル-4,4'-ビピリミジン(Me2bpm)を反応させた場合、四核Cu(I)メタラマクロサイクリックCO付加体[Cu4(Me2bpm)4(CO)4](BF4)4が、一方[Cu(CH3CN)4]PF6とMe2bpmを反応させた場合、メタラカリックス[3]アレン型の三核Cu(I)-CO付加体が連結された2次元Cu(I)配位高分子{ { [Cu3(Me2bpm)3(CO)3](PF6)3}[Cu(CH3CN)]BF4}がアニオン選択的に自己集積化されることを見出した。
  • 4,4'-ビピリミジン類縁配位子による新規なCu(I)メタラマクロサイクリック-エチレン付加体の自己集積化  [通常講演]
    前川 雅彦; 富永 登志; 鍋井 淳宏; 大久保 貴志; 黒田 孝義; 宗像 惠; 北川 進
    日本化学会第89春季年会 2009年03月 船橋 日本化学会第89春季年会
     
    C2H4雰囲気下、[Cu(CH3CN)4]BF4と6,6'-ジメチル-4,4'-ビピリミジン(Me2bpm)を反応させた場合、三核Cu(I)メタラマクロサイクリック-エチレン付加体が、[Cu(CH3CN)]+に繋げられ、その空孔内にBF4-アニオンを捕捉した二次元Cu(I)配位高分子 {[Cu4(Me2bpm)3(C2H4)3(CH3CN)](BF4)4}nが自己集積化した。また[Cu(CH3CN)4]BF4と6,6'-ジフェニル-4,4'-ビピリミジン(Ph2bpm)を反応させた場合、単核Cu(I)-エチレン錯体[Cu(Ph2bpm)(C2H4)]BF4が生成した。
  • 架橋能を有するコバルトSCO 錯体によるCu(I)配位高分子の合成と物性  [通常講演]
    泉 貴文; 鍋井 淳宏; 前川 雅彦; 大久保 貴志; 黒田 孝義
    第58回錯体化学討論会 2008年09月 金沢 第58回錯体化学討論会
  • qsal 誘導体を用いた多核FeSCO 錯体の合成と物性  [通常講演]
    玉浦 裕貴; 鍋井 淳宏; 富永 登志; 前川 雅彦; 大久保 貴志; 黒田 孝義
    第58回錯体化学討論会 2008年09月 金沢 第58回錯体化学討論会
  • Bis-Schiff 塩基配位子と架橋配位子からなる一次元鎖Fe(II)スピンクロスオーバー錯体の合成と物性  [通常講演]
    清水 俊行; 鍋井 淳宏; 大久保 貴志; 前川 雅彦; 黒田 孝義
    第58回錯体化学討論会 2008年09月 金沢 第58回錯体化学討論会
  • Bis-Schiff 塩基配位子を用いたFe(III)錯体と架橋配位子との一次元鎖錯体の磁性および構造におよぼすアニオン効果  [通常講演]
    鍋井 淳宏; 大久保 貴志; 前川 雅彦; 黒田 孝義
    第58回錯体化学討論会 2008年09月 金沢 第58回錯体化学討論会
  • 新規なCu(I)メタラマクロサイクリックエチレン付加体の合成および構造  [通常講演]
    前川 雅彦; 富永登志; 鍋井淳宏; 大久保 貴志; 黒田 孝義; 宗像 惠; 北川 進
    第58回錯体化学討論会 2008年09月 金沢 (金沢大学角間キャンパス) 第58回錯体化学討論会
     
    [Cu(CH3CN)4]BF4と4,4'-ビピリミジン(bpm)をエチレン下反応させ空孔内にBF4アニオンを捕捉したメタラカリックスアレンが繋がった2次元Cu(I)-bpm-エチレン付加体の構築に成功した。本研究ではさらに6,6'-ジフェニル-4,4'-ビピリミジン(Ph2bpm)を用い、同様に合成を行ない黄色針状結晶を得た。IR測定などからCu(I)-Ph2bpm-C2H4錯体の生成を確認した。
  • Bis-Schiff 塩基配位子と架橋配位子から構成される一次元鉄(II)錯体の合成とそのスピンクロスオーバー  [通常講演]
    清水 俊行; 辻 博貴; 鍋井 淳宏; 大久保 貴志; 黒田 孝義
    日本化学会第88春季年会 2008年03月 東京 日本化学会第88春季年会
  • シアノ基を有するコバルトSCO錯体で架橋された配位高分子の合成と物性  [通常講演]
    泉 貴文; 玉浦 裕貴; 鍋井 淳宏; 大久保 貴志; 黒田 孝義
    日本化学会第88春季年会 2008年03月 東京 日本化学会第88春季年会
  • bis-Schiff塩基配位子を有するFe錯体の構造とスピンクロスオーバー挙動  [通常講演]
    鍋井 淳宏; 大久保 貴志; 前川 雅彦; 宗像 惠; 黒田 孝義
    日本化学会第88春季年会 2008年03月 東京 日本化学会第88春季年会
  • アニオンテンプレート法による新規なCu(I)およびAg(I)配位高分子の自己集積化  [通常講演]
    前川 雅彦; 富永登志; 鍋井淳宏; 黒田 孝義; 宗像 惠; 大久保 貴志; 北川 進
    日本化学会第88春季年会 2008年03月 日本化学会 日本化学会第88春季年会
     
    アニオンテンプレート法を用いて4-(2-ピリジル)ピリミジン(pprd)および4,4'-ビピリミジン(bpm)を配位子とする新規な銅(I)および銀(I)配位高分子を自己集積化させることを試み、特にエチレン雰囲気下、[Cu(CH3CN)]BF4とbpmを反応さた場合、空孔内にBF4-アニオンを捕捉したC2H4の脚を有するメタラカリックス[3]アレンエチレ付加体が2次元シート構造状に繋がった興味深い{ { [Cu3(pprd)3(C2H4)3](BF4)3}[Cu(CH3CN)]BF4}が自己集積化することを見出した。
  • Synthesis and characterization of metal-organic frameworks with Mn12 SMM’s as guests  [通常講演]
    Yu Zhong; 鍋井 淳宏; 大久保 貴志; 黒田 孝義
    第57回錯体化学討論会 2007年09月 名古屋 第57回錯体化学討論会
  • シアノ基を有するFe-terpy系錯体で架橋された配位高分子の合成と物性  [通常講演]
    玉浦 裕貴; 鍋井 淳宏; 大久保 貴志; 宗像 惠; 黒田 孝義
    第57回錯体化学討論会 2007年09月 名古屋 第57回錯体化学討論会
  • bis-Schiff塩基配位子を有するFeおよびCo錯体の構造とスピンクロスオーバー挙動  [通常講演]
    鍋井 淳宏; 大久保 貴志; 前川 雅彦; 宗像 惠; 黒田 孝義
    第57回錯体化学討論会 2007年09月 名古屋 第57回錯体化学討論会

MISC

共同研究・競争的資金等の研究課題

  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2022年04月 -2025年03月 
    代表者 : 大久保 貴志
  • 日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2020年04月 -2022年03月 
    代表者 : 大久保 貴志
     
    本研究課題では新たな導電性ソフトクリスタルの開発と光電子デバイスへの応用を試みた。具体的には、導電性と発光特性を兼ね備えた導電性答性ソフトクリスタルを有機ELや有機薄膜太陽電池、電界効果トランジスタ(FET)、二次電池、熱電変換素子などの光電子デバイスへと応用することで、ソフトクリスタルの実用の可能性を検証することを目的として研究を実施した。 1)本研究では導電性と発光特性を兼ね備えたソフトクリスタルを創成するために、ハロゲン化銅と含窒素π共役配位子からなる配位高分子を合成した。これら配位高分子はいずれも導電性を示し、1(M+X)LCTからのエネルギー移動による三重項クラスターセンター(3CC)からの発光、熱活性化遅延蛍光(TADF)、リン光など、配位高分子ごとに異なるメカニズムによる発光を示すことが明らかになった。 2)本研究で合成した導電性ソフトクリスタルを用いたリチウムイオン電池を作製し、その充放電特性を検討した。その結果、コバルト酸リチウムを正極とした二次電池と同程度の150 mAh/gの容量を示すことが明らかになった。XPSの測定から充放電の過程で導電性ソフトクリスタルの細孔内にLi+イオンとBF4-アニオンが出入りしている可能性があることが示唆された。 3)ヨウ化銅(I)とフェナントリジンを順次積層した薄膜をアセトニトリル蒸気を用いて溶媒アニールすることで、配位高分子薄膜の生成を確認した。この配位高分子薄膜を用いて有機EL素子を作製し、発光特性を評価した。 4)銅イオンの変位により巨大な誘電応答と高いキャリア移動度を示す電場応答性ソフトクリスタルについて、断熱型熱量計を用いた熱容量測定を行い、その相転移現象に関して検討した。その結果、合成直後の結晶は準安定層であることが示唆され、このことが巨大な誘電応答と高いキャリア移動に関与している可能性があることが明らかになった。
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2019年04月 -2022年03月 
    代表者 : 大久保 貴志
     
    有機薄膜太陽電池は環境に優しい軽くフレキシブルな太陽電池である。この薄膜太陽電池はプラスチック基板上にロール・ツー・ロールなどの低温印刷プロセスを用いて安価に大量に製造できるため、将来的にはユビキタスな電源装置としての幅広い用途が期待されている。本研究ではこの有機薄膜太陽電池に応用可能な新たな導電性配位高分子の開発を目的に研究を行った。薄膜太陽電池の半導体材料として用いるためには、その構造とバンドギャップ、キャリア制御が重要であり、本研究ではハロゲン化銅(I)とアクセプター性のπ共役配位子を組み合わせることで実現した。更に、実際に有機薄膜太陽電池のバッファ層として有用であることを見いだした。
  • 日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2018年04月 -2020年03月 
    代表者 : 大久保 貴志
     
    電場応答性ソフトクリスタルは、その巨大な誘電率を利用した新しい光電子デバイスへの応用が期待できる。そこで本研究では、巨大な誘電率を有する電場応答性ソフトクリスタルを電界効果トランジスタ(FET)やキャパシタ、熱電変換素子などの光電子デバイスへと応用することで、ソフトクリスタルの実用の可能性を検証することを目的として研究を実施した。 ①電場応答性ソフトクリスタルの基礎物性評価:ジブチルジチオカルバミン酸を配位子とした電場応答性ソフトクリスタルの薄膜サンプルを作製し、キャリア輸送特性や誘電性に関して検討した。 ②電場応答性ソフトクリスタルを用いたFETの作製:電場応答性ソフトクリスタルをFETへ応用することで低電圧駆動FETが作製できる可能性があることを見いだしている。ただし、これまでのところ電場応答性ソフトクリスタルの単結晶FETに関しては再現性が非常に乏しかった。そこで本年度は真空下でFETの測定が可能な環境を整え、銅フタロシアニンなど標準的な有機半導体に関してFETの動作確認を行った。 ③新規電場応答性ソフトクリスタルの合成:本研究では、ジチオカルバミン酸系に加え、ヘキサアザトリフェニレン誘導体を用いたソフトクリスタルの開発も行っている。臭化銅(I)とヘキサアザトリフェニレン配位子から成る半導体材料は真空蒸着による成膜も可能であり、それら薄膜の物性評価を行った。 ④電場応答性ソフトクリスタルの電子デバイスへの応用:上記臭化銅(I)とヘキサアザトリフェニレン誘導体からなる半導体材料を用いた薄膜太陽電池の開発を行っている。これまでのところ、この電場応答性ソフトクリスタルを有機薄膜太陽電池のホール輸送層に利用した際に、短絡電流密度が増大し、結果として光電変換効率が向上することを見いだしている。この短絡電流密度の増大に電場応答性ソフトクリスタルの光伝導性が関与している可能性を見いだした。
  • 強誘電性配位高分子を用いた低電圧駆動メモリトランジスタの創製
    日本学術振興会:科学研究費補助金(基盤研究(C))
    研究期間 : 2013年04月 -2016年03月 
    代表者 : 大久保貴志
  • 強誘電性配位高分子複合界面の創製と光電変換素子への応用
    科学技術振興機構:さきがけ
    研究期間 : 2012年09月 -2016年03月 
    代表者 : 大久保貴志
  • 高キャリア移動度を有する配位高分子の合成と電界効果トランジスタへの応用
    日本学術振興会:科学研究費補助金(若手研究(B))
    研究期間 : 2011年04月 -2013年03月 
    代表者 : 大久保貴志
  • 産学が連携した研究開発成果の展開 研究成果展開事業 研究成果最適展開支援プログラム(A-STEP) 探索タイプ
    研究期間 : 2011年 -2012年 
    代表者 : 大久保 貴志
     
    本研究ではこれまで金属イオンと架橋有機配位子からなる種々の配位高分子を独自に開発し、最近ではそれら配位高分子を添加したバルクヘテロ型有機薄膜太陽電池の光電変換効率が従来の有機薄膜太陽電池に対して向上することを見いだした。そこで、本研究課題ではこの研究シーズを発展させ、現行のP3HT-PCBM系の特性を上回る高効率有機薄膜太陽電池の開発を目指すとともに、技術移転可能な基盤技術を確立することを目的に研究を行った。その結果、ジェットミルにて粒径制御を行った配位高分子を有機薄膜層に添加することで、再現性良く高い光電変換効率を示すバルクヘテロ型有機薄膜太陽電池が作製できることを実証した。
  • 多重機能性混合原子価集積型金属錯体の開発
    科学技術振興機構:さきがけ
    研究期間 : 2007年10月 -2011年03月 
    代表者 : 大久保貴志
  • 日本学術振興会:科学研究費助成事業 挑戦的萌芽研究
    研究期間 : 2007年 -2009年 
    代表者 : 大久保 貴志
     
    イオン伝導体は化学物質のエネルギーを直接電気エネルギーに変換する電池システムの固体電解質として利用できるため、近年の携帯電話やノート型パソコンを始めとするモバイル機器の爆発的な普及に伴い、その需要は急速に拡大している。本研究では無機・有機の複合材料である金属錯体を集積化させる事で、イオン伝導性と電子伝導性が共存する、新た混合伝導体を開発する事を目的として研究を行った。今年度は特に前年度に引き続き新規層間化合物の合成およびそのインピーダンス特性に関する研究を行った。その過程で、層間にドナー性分子であるテトラチアフルバレン(TTF)のカチオンを含む二次元層間化合物の合成に成功した。この化合物は室温で2×10^<-6>S/cmと高い伝導度を示し、インピーダンス測定による緩和時間から見積もった移動度は480cm^2/Vsに達することが明らかとなった。密度汎関数法によるバンド計算の結果、この系では臭化銅の二次元レイヤー間に二価のカチオンとしてTTFが取り込まれることで臭化銅レイヤーからTTFカチオンへの電荷移動に起因するキャリア注入が実現しており、これによって高い伝導度が発現していることが示唆された。また、室温以上で不可逆な相転移を示し、それに伴い対称性の低下と伝導性の減少が観測された。このことは上記の化合物が安定な準安定相を有しており、光等の外部電場によってキャリア制御ができる可能性を示唆している。その他、BEDT-TTFやTMT-TTFなど一連のドナー分子を用いた新規層間化合物の合成にも成功した。ただし、当初の目的であったイオン伝導系に関しては、これまで合成した化合物の一部でその可能性が示唆される結果が得られたものの、伝導機構および構造の詳細は明らかになっていない。
  • 日本学術振興会:科学研究費助成事業 萌芽研究
    研究期間 : 2003年 -2004年 
    代表者 : 大久保 貴志
     
    本研究では今年度「銅I-II混合原子価金属錯体を用いたスィッチング素子の創成」に向けて主に混合原子価状態を有する新規金属錯体集積体の合成を行って来た。この様な金属錯体は外場によって金属イオン間で電子移動が起こる可能性があり(IVCT)、金属イオン間のエネルギーレベルと配位子のエネルギーレベルを十分考慮して合成を行えば、電子変位型の強誘電性材料が合成できる可能性があるのではないかと考えている。このような観点から銅の混合原子価錯体を合成したところ今年度は多くの化合物を得ることができた。特に、ジチオカルバミン酸二核錯体にアクセプター性分子として有名なTCNQを混ぜ合わせたところ、銅二核錯体2分子に対して、TCNQ1分子を含んだ新規電荷移動錯体を得ることができた。この系においてはTCNQは形式的には中性状態であったが、IRスペクトルを測定したところ、-0.2電子の電荷移動が確認された。また、二次元構造を有する金属錯体[Cu^(dtc)_2Cu^I_4Cl_3][Cu^(dtc)_2]_2(Fe^Cl_4)}_nに関しては強誘電性を発現する事が明らかになった。この錯体は基本的には5核銅ユニットをCu^(dtc)_2が架橋した二次元シート構造をとっている。この、5核銅ユニットにおいては中心ハロゲンイオンが電場に応答し移動することによって強誘電性が発現することが確かめられた。非誘電率の温度依存性を測定した所、200K以上で非誘電率の増大が観測された。更に高温になると誘電率は極端に増大し始めるが、このときは化合物の分解を伴っていることが明らかになった。また、強誘電テスタを利用して分極Pの電圧E依存性を測定した所、室温付近で明らかなヒステリシスが観測できた。
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2000年 -2003年 
    代表者 : 三谷 忠興; 加藤 昌子; 安 正宣; 大久保 貴志; 下田 達也; 欧陽 建勇
     
    有機薄膜を用いたELレーザ開発はいま産学界の関心の的となっているが、まだ成功したとの報告はない。その最大の要因は、レーザ発振に必要な励起子密度が得られていないことによるものと考えられる。この問題を解決するには、必然的に発光層内ての電子およびホールの密度の増加と高い発光効率とともに発光寿命の最適化が要求される。前者の解決策の一つとして、ブルームライン方式を用いた高速パルス発光機構による高速化を行いその有用性を実証した。後者については、まず、Alq_3をモデルとして、キノリノール配位子の代わりに硫黄原子を骨格に含んだ配位子を用いてEL材料の合成を行った。硫黄原子は軌道の広がりが大きいため隣接分子との重なりが大きく、移動度の増大につながるものと期待した。そこで硫黄を含んだ配位子2-(o-hydroxyphenyl)thiazole (PhTZ)を用いた新規亜鉛2核錯体を合成した。この錯体はZn_2(PhTZ)_4の組成を有しPzTZ配位子の一部がスタックした二次元積層構造を有し、この錯体は発光波長497nm青色発光を示し、EL素子は最高輝度1050cd/cm^2を示した。さらに、この配位子を用いてA1との錯体を合成すると発光波長の異なる結晶構造を有する2種類のEL素材が得られ、且つ両者か共存することから、白色のELを持つ素材が得られたことは注目に値する。また、いくつかのPhTZ誘導体を新たに合成し、多核構造を有する新規亜鉛錯体を合成し、X線構造解析にて結晶構造を決定した。 これら新規亜鉛錯体に関する研究結果に関して次に示す。まず、Alq_3および新規単核錯体Alptz_3、Alppo_3に関する研究から、中心金属周りの配位結合距離の分布がアモルファス化という点では重要であり、更に結合距離の違いによって生じる準安定相がそれぞれ異なる発光を示す事が明らかになった。また中心金属をアルミから亜鉛で交換する事によってZnppo_2、Zn_2ptz_4とZn_3ppo_6という新規オリゴマー錯体の合成に成功し、なおかつこれらオリゴマー錯体に関してπ-πエネルギギャプのワイドコントロールが可能である事か明らかになった。更に異なる二種類の配位子を含むZn_4ppo_2q_6という新規化合物を合成し、有機EL材村としての評価実験を行った。その結果、オリゴマー金属錯体においては通常の有機高分子では考えられない発光特性を示す事が明らかとなった。すなわち、通常の有機高分子では発光特性が異なる二種類のユニットを化学結合により連結した場合、最もエネルギーの小さいユニットからのみ発光が観測されるか、オリゴマー金属錯体においてはそれぞれのユニットが発光核となり異なる色の発光が共存することが明らかになった。これらの結果を踏まえると、オリゴマー錯体てスピン-軌道相互作用か大きい金属の導入、またオリゴマー錯体で二種類以上の金属と二種類以上の配位子を導入する事によって、今まで得られていない白色発光体に関しての新しい設計指針を提案できる。
  • 日本学術振興会:科学研究費助成事業 若手研究(B)
    研究期間 : 2001年 -2002年 
    代表者 : 大久保 貴志
     
    有機エレクトロルミネッセンス(EL)材料は次世代ディスプレイとして今その実用化に向けた研究開発が活発に行われている。本研究はこの有機ELを新しいレーザの開発に応用しようというものである。そのために、新しい多核金属錯体の合成とブルームライン回路を利用した新しいEL発光機構の応用という2つの観点からELレーザの作製を試みた。本研究において、いくつかの新規発光材料の合成を行った。これらは大きく分けると、Au多核錯体とチアゾール骨格を有する配位子を用いたAl及びZn錯体の2つに大別できる。Au2核錯体はAu-Auの特異な相互作用により非常に寿命の長い発光を示すことが知られている。この様な励起寿命の長い発光を示す材料をELデバイスとして応用することによりレーザ発振に必要な誘導放出を引き起こすことができると考えた。具体的には[Au(PR_3)(mbtz)]_2の組成を有する新規Au2核錯体を合成し、エックス線構造解析によりその結晶構造明らかにした。ここでRはphenyl基、thiophenyl基、furyl基であり、mbtzは2-mercapto-benzothiazoleである。それぞれの錯体はAu2核構造を有し、Au-Au間距離はファンデルワールス半径の和より小さくなっている。このことから明らかにAu-Au間に特異な相互作用が働いている事がわかる。これらの錯体は紫外光を照射することにより緑色から黄色の発光が確認された。[Au(PPh_3)(mbtz)]_2を真空蒸着により薄膜化し、XPSの測定を行ったところAu(PPh_3)(mbtz)の組成は保持している事が明らかとなった。この錯体をホール輸送層として用いることによりELデバイスを作製した。この素子に直流電圧を印加したところ10V付近で緑色の発光が確認されたが、発光が弱く寿命も短かったためスペクトル、および輝度の測定には至らなかった。一方、チアゾール骨格を有する配位子を用いても、いくつかの新規発光材料を合成した。これら錯体を用いてEL素子を作製し、ブルームライン回路を用いた高速パルス印加における発光を調べた。これら素子は70V印加時においてもショートは起こらず安定に動作した。この時の輝度はZn(II)二核錯体で11000cd/m^2であった。この二核錯体における発光輝度は青色発光で最も光る材料である上記のLiBq_4の値を上まわった。ただし、これらの素子においてもレーザ発振の兆候は確認できなかった。 本研究結果に関してはChem. Mater及びChem. Phys. Lett.に投稿中である。

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