Updated on 2024/04/02

写真a

 
IGUCHI Hiroaki
 
Organization
Graduate School of Engineering Materials Chemistry 2 Associate professor
Graduate School
Graduate School of Engineering
Undergraduate School
School of Engineering Chemistry and Biotechnology
Title
Associate professor
External link

Degree 3

  1. Doctor(Science) ( 2011.3   Tohoku University ) 

  2. Master(Science) ( 2008.3   Tohoku University ) 

  3. Bachelor(Science) ( 2006.3   Tohoku University ) 

Research Interests 3

  1. Coordination Chemistry

  2. Supramolecular Chemistry

  3. Materials Chemistry

Research Areas 2

  1. Nanotechnology/Materials / Functional solid state chemistry

  2. Nanotechnology/Materials / Inorganic/coordination chemistry

Current Research Project and SDGs 1

  1. 導電性多孔質分子結晶の開発

Research History 3

  1. Nagoya University   Graduate School of Engineering Materials Chemistry 2   Associate professor

    2022.3

  2. Tohoku University   Department of Chemistry, Graduate School of Science   Assistant Professor

    2013.4 - 2022.2

  3. Kyushu University   Department of Chemistry and Biochemistry, Graduate School of Engineering   Research Fellow (SPD) of the Japan Society for the Promotion of Science (JSPS),

    2011.4 - 2013.3

Education 3

  1. Tohoku University   Graduate School of Science   Department of Chemistry

    2008.4 - 2011.3

  2. Tohoku University   Graduate School of Science   Department of Chemistry

    2006.4 - 2008.3

  3. Tohoku University   School of Science   Department of Chemistry

    2002.4 - 2006.3

Professional Memberships 6

  1. 日本化学会

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  2. 錯体化学会

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  3. 分子科学会

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  4. 高分子学会

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  5. 日本物理学会

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  6. 日本吸着学会

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Committee Memberships 2

  1. 有機固体若手の会   世話人  

    2017.9 - 2019.3   

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    Committee type:Academic society

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  2. 錯体化学会   男女共同参画委員会 委員  

    2015.10 - 2018.8   

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    Committee type:Academic society

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Awards 6

  1. 日本化学会第38回「若い世代の特別講演会」 講演証

    2024.3   日本化学会   電子状態の自在制御を目指した多孔性分子導体の開発

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    Award type:Award from Japanese society, conference, symposium, etc. 

  2. Award for Encouragement of Research in the 29th Annual Meeting of MRS-J

    2020.1   Syntheses of Porous Molecular Conductors by Electrochemical Self-Assembly of Coordination Polymers

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  3. 第4回ライジング・スター賞

    2016.4   CREST「分子技術」  

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  4. 化学専攻賞

    2011.3   東北大学大学院理学研究科化学専攻  

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  5. 平成21年度錯体化学若手の会夏の学校 ポスター賞

    2009.8   錯体化学若手の会   ナフタレンジイミド誘導体を対カチオンに有する鉛ハライド錯体の合成と物性

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  6. 第58回錯体化学討論会ポスター賞

    2008.9   錯体化学会   溶媒吸脱着による二元系MMX-Chain錯体の電子相制御

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Papers 68

  1. Chemical pressure-induced Pt<sup>III</sup>–I Mott–Hubbard nanowire, [Pt(en)<sub>2</sub>I](Asp-C<sub><i>n</i></sub>)<sub>2</sub>·H<sub>2</sub>O (13 ≤ <i>n</i>), detected <i>via</i> polarized infrared spectroscopy Reviewed

    Shohei Kumagai, Takefumi Yoshida, Hiroaki Iguchi, Masanori Wakizaka, Nobuto Funakoshi, Masahiro Yamashita, Shinya Takaishi

    Chemical Communications   Vol. 59 ( 95 ) page: 14118 - 14121   2023.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Royal Society of Chemistry (RSC)  

    Polarized FT-IR spectra of the Pt–I semiconductive nanowire, [Pt(en)2I](Asp-C<sub>n</sub>)<sub>2</sub>·H<sub>2</sub>O, revealed that the first Pt<sup>III</sup>–Pt<sup>III</sup> AV state for n ≥ 13.

    DOI: 10.1039/d3cc04285e

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  2. Hexagonal crystalline Magnus’ green salt analogues prepared from hydroxy-functionalised Pt and Pd complexes Reviewed

    Mohammad Rasel Mian, Unjila Afrin, Shinya Takaishi, Brian K. Breedlove, Masahiro Yamashita, Hiroaki Iguchi

    Dalton Transactions     2023.8

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    New Magnus’ green salt (MGS) analogues, [M(dabdOH)2][MCl4]·2H2O (dabdOH = (2S,3S)-2,3-diaminobutane-1,4-diol; M = Pd (1) and M = Pt(2)), in which [M(dabdOH)2]2+ and [MCl4]2− are stacked alternately to form linear chains, were obtained as hexagonal plate crystals. The hexagonal shape and large crystal size are unprecedented features as MGS analogues. An unusual trigonal grade separation of chain complexes has been revealed by the structural analysis. 1 and 2 exhibited remarkable yellow and pink colours, respectively, which are derived from weak M⋯M interactions. The dabdOH ligand, which has an additional hydrogen donor group (hydroxy group), produces a multiple-hydrogen-bond network. The combination of intrachain and interchain hydrogen bonds gives a two-dimensional (2D) hydrogen-bond sheet, and each 2D sheet is indirectly connected by hydrogen bonds via lattice water molecules. The OH-functionalised ligand greatly increases the hydrophilicity of the MGS analogues and yields the largest single crystals of all MGS analogues reported so far. The trigonal grade-separated chain structure is likely due to the geometric matching between the periodicity of chains and the short axis width of the chain. This strategy opens up new insight for preparing large crystals of MGS analogues and for constructing trigonal grade-separated nanowires in molecular crystals.

    DOI: 10.1039/d3dt01700a

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  3. Single-Crystal Structures of Benzenehexathiol and Its Disulfide Forms Reviewed

    Yuta Chiba, Tappei Tanabe, Kazuma Koizumi, Ryojun Toyoda, Hiroaki Iguchi, Shinya Takaishi, Ryota Sakamoto

    Inorganic Chemistry   Vol. 62 ( 29 ) page: 11731 - 11736   2023.7

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    Oligothiols are useful as building blocks in the construction of disulfide-based macrocycles and polymers or as ligands for coordination polymers. Above all, benzenehexathiol (BHT) is a particularly important molecule, as it is used to construct conductive two-dimensional MOFs. Despite the desire to clarify its structure and isolate it to high purity, the chemical instability of BHT has hampered single-crystal X-ray structure analysis of intact BHT. In addition, the synthesis of discrete disulfide molecules of BHT has not been reported. Here, we succeed in obtaining the single crystals of intact BHT, which is analyzed by single crystal X-ray structure analysis. Furthermore, the structures of a group of molecules with intermolecular disulfide bonds (BHT·4im and BHT2·2TBA, im = imidazole, TBA = tetrabutylammonium cation) obtained by processing BHT in the presence of bases are determined.

    DOI: 10.1021/acs.inorgchem.3c01734

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  4. Deprotonation-Induced Color Modulation in N,N′-Dihydroxynaphthalenediimide-Based Organic Crystals Reviewed International journal

    Tappei Tanabe, Tetsu Sato, Kentaro Fuku, Shinya Takaishi, Hiroaki Iguchi

    ChemPlusChem   Vol. 88 ( 7 ) page: e202300140   2023.7

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    N,N'-dihydroxy-1,4,5,8-naphthalenetetracarboxdiimide (NDI-(OH)2) has attracted much attention in recent years, because its doubly deprotonated state, (O-NDI-O)2-, has metal-coordination ability and characteristic electronic transition useful for designing electronic and optical functions. In contrast, a molecular crystal with the mono-deprotonated (HO-NDI-O)- ion remains unknown. We herein report an organic crystal containing non-disproportionated  (HO-NDI-O)- ions, which are connected by very strong O-H-O hydrogen bonds. Its lowest energy absorption band (450 to 650 nm) is observed in between that of NDI-(OH)2 (380 nm) and isolated (O-NDI-O)2- (500 to 850 nm) species, consistent with the molecular orbital calculations. This absorption originates from the electronic transition from deprotonated imide-based orbitals to NDI-core orbitals, which can be influenced by the hydrogen bonds around imide group. Consequently, the optical properties of NDI-(OH)2 can be modulated by the stepwise deprotonation and hydrogen-bonding interactions.

    DOI: 10.1002/cplu.202300140

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  5. Beyond the Conventional Limitation of Photocycloaddition Reaction in the Roomy Nanospace of a Metal-Organic Framework Reviewed

    Misaki Nakagawa, Shinpei Kusaka, Atsushi Kiyose, Toshinobu Nakajo, Hiroaki Iguchi, Motohiro Mizuno, Ryotaro Matsuda

    Journal of the American Chemical Society   Vol. 145 ( 22 ) page: 12059 - 12065   2023.6

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    Topochemical reactions provide selective products based on the molecular position; however, they generally require molecules to be placed in strictly limited orientations and distances, making them less versatile. In this study, we found that by confining trans-4-styrylpyridine (4-spy) as a reactive substrate in a flexible metal-organic framework (MOF) nanospace, [2+2] cycloadducts can be selectively obtained, even when the distance between two C═C bonds of 4-spy in the crystal is 5.9 Å, which is much larger than the conventionally observed upper limit (4.2 Å). Such an unusual cyclization reaction is suggested to occur due to the transient proximity of the 4-spy due to the “swing” motion in the nanospace. The MOF nanospace, with its high degree of molecular structural freedom, can be applied to different platforms that do not require the fine constraints of reactive distances for solid-phase reactions.

    DOI: 10.1021/jacs.3c01225

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  6. Structure and Physical Properties of Alternately Stacked Donor-acceptor Complexes with 5,11-Dimethyl-5,11-dihydroindolo[3,2-b]carbazole Reviewed

    Yuta Chiba, Tappei Tanabe, Shohei Koyama, Shuntaro Yamanaka, Shinya Takaishi, Ryota Sakamoto, Hiroaki Iguchi

    CHEMISTRY LETTERS   Vol. 52 ( 6 ) page: 488 - 491   2023.6

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    Alternately stacked donor-acceptor (DA) complexes con-taining 5,11-dimethyl-5,11-dihydroindolo[3,2-b]carbazole (ICZ-Me) as a donor were synthesized for the first time by crystallization with three different acceptor molecules. Among them, the DA complex with tetracyanoethylene (TCNE) exhibited the largest effective charge transfer integral (ItDAI), degree of charge transfer (& mu;), and electrical conductivity (& BULL;). Designing the noncovalent interaction is important to fix the position of acceptors with respect to ICZ-Me and to control the electronic properties.

    DOI: 10.1246/cl.230175

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  7. Creation of single molecular conjugates of metal-organic cages and DNA. Reviewed International journal

    Toshinobu Nakajo, Shinpei Kusaka, Haruka Hiraoka, Kohei Nomura, Noriaki Matsubara, Rintaro Baba, Yuki Yoshida, Kosuke Nakamoto, Masakazu Honma, Hiroaki Iguchi, Takayuki Uchihashi, Hiroshi Abe, Ryotaro Matsuda

    Chemical communications (Cambridge, England)   Vol. 59 ( 33 ) page: 4974 - 4977   2023.4

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    Here we report the development of an equimolar conjugate of a metal-organic cage (MOC) and DNA (MOC-DNA). Several MOC-DNA conjugates were assembled into a programmed structure by coordinating with a template DNA having a complementary base sequence. Moreover, conjugation with the MOC drastically enhanced the permeability of DNA through the lipid bilayer, presenting great potential as a drug delivery system.

    DOI: 10.1039/d3cc00460k

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  8. Quinoid-Based Three-Dimensional Metal-Organic Framework Fe<inf>2</inf>(dhbq)<inf>3</inf>: Porosity, Electrical Conductivity, and Solid-State Redox Properties Reviewed

    Shraddha Gupta, Haruki Tanaka, Kentaro Fuku, Kaiji Uchida, Hiroaki Iguchi, Ryota Sakamoto, Hiroaki Kobayashi, Yoshiyuki Gambe, Itaru Honma, Yutaka Hirai, Shinya Hayami, Shinya Takaishi

    Inorganic Chemistry   Vol. 62 ( 16 ) page: 6306 - 6313   2023.4

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    We report the synthesis, characterization, and electronic properties of the quinoid-based three-dimensional metal-organic framework [Fe2(dhbq)3]. The MOF was synthesized without using cations as a template, unlike other reported X2dhbq3-based coordination polymers, and the crystal structure was determined by using single-crystal X-ray diffraction. The crystal structure was entirely different from the other reported [Fe2(X2dhbq3)]2-; three independent 3D polymers were interpenetrated to give the overall structure. The absence of cations led to a microporous structure, investigated by N2 adsorption isotherms. Temperature dependence of electrical conductivity data revealed that it exhibited a relatively high electrical conductivity of 1.2 × 10-2 S cm-1 (Ea = 212 meV) due to extended d-π conjugation in a three-dimensional network. Thermoelectromotive force measurement revealed that it is an n-type semiconductor with electrons as the majority of charge carriers. Structural characterization and spectroscopic analyses, including SXRD, Mössbauer, UV-vis-NIR, IR, and XANES measurements, evidenced the occurrence of no mixed valency based on the metal and the ligand. [Fe2(dhbq)3] upon incorporating as a cathode material for lithium-ion batteries engendered an initial discharge capacity of 322 mAh/g.

    DOI: 10.1021/acs.inorgchem.2c04313

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  9. Data Mining from XANES Spectra of Nickel Complexes for Structure Estimation Reviewed

    Kentaro Fuku, Takefumi Yoshida, Tetsu Sato, Hiroaki Iguchi, Shinya Takaishi, Ryota Sakamoto, Hitoshi Abe

    Chemistry Letters   Vol. 52 ( 4 ) page: 289 - 291   2023.4

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:The Chemical Society of Japan  

    Estimating the coordination environment of non-crystalline metal complexes has been an important issue. In this study, we applied machine learning methods to extract features of coordination number and coordination elements from X-ray absorption near edge structure (XANES) spectra of 44 Ni complexes. The spectra were clearly classified according to the coordination number and coordination elements. The similarity between spectra was visualized as a 2D map by dimensionality reduction using multidimensional scaling (MDS).

    DOI: 10.1246/cl.230028

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  10. Observation of slow magnetic relaxation phenomena in spatially isolated π-radical ions Reviewed

    Shohei Koyama, Kazunobu Sato, Masahiro Yamashita, Ryota Sakamoto, Hiroaki Iguchi

    Physical Chemistry Chemical Physics   Vol. 25 ( 7 ) page: 5459 - 5467   2023.1

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    The use of molecular spins as quantum bits is fascinating because it offers a wide range of strategies through chemical modifications. In this regard, it is very interesting to search for organic radical ions that have small spin-orbit coupling values. On the other hand, the feature of the magnetic relaxation of π-organic radical ions is rarely exploited due to the difficulty of spin dilution, and π-stacking interaction. In this study, we focus on N,N′,N′′-tris(2,6-dimethylphenyl)benzenetriimide (BTI-xy), where three xylene moieties connected to the imide groups cover the π-plane of the BTI core. As a result, BTI-xy radical anions without π-stacking interaction were obtained. This led to the slow magnetization relaxation, which is reported for the first time in organic radicals. Furthermore, the relaxation times in a solution state revealed the importance of spin interaction.

    DOI: 10.1039/d2cp06026d

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  11. Orthogonal Grade-Separated Nanowiring of Molecular Single Chains Reviewed

    Hirotaka Nakajima, Hiroaki Iguchi, Shinya Takaishi, Tetsu Sato, Brian K. Breedlove, Ryuta Ishikawa, Satoshi Kawata, Qingyun Wan, Masanori Wakizaka, Masahiro Yamashita

    Chemistry of Materials   Vol. 35 ( 1 ) page: 116 - 122   2023.1

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    Quasi-one-dimensional (1D) compounds are suitable models to develop future nanodevices. The critical issue is that most of the several hundred reported 1D compounds adopt parallel arrangements. Here, we report the first example of an orthogonal grade-separated arrangement of the halogen-bridged metal complex (MX-Chain) [PtII(en)2][PtIVCl2(en)2][FeIIICl5]2, abbreviated as [Pt(en)2Cl][FeIIICl5] (en = ethylenediamine), which is the first example of that arrangement of molecular single chains. The space group and topology are coincidentally same as alchemists' gold, Hg3-delta AsF6, which aligns as atomic single chains. This molecular nanostructure is very rare and valuable as a three-dimensional (3D) nanowiring model. The hydrogen bond network found in [Pt(en)2Cl][FeIIICl5] represents a new strategy for making such nanostructures. The structural and optical relationships are similar to those of typical Pt(II)/Pt(IV) mixed valent MX-Chains in charge-density-wave (CDW) states. Polarized Raman spectra strongly supported the presence of orthogonal grade-separated chains in CDW states. Thus, this work proved the concept of molecular single-chain grade-separated nanowiring.

    DOI: 10.1021/acs.chemmater.2c02720

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  12. Porous Mn2+ Magnet with a Pt–Cl Framework: Correlation between Water Vapor Adsorption/Desorption and Slow Magnetic Relaxation Reviewed

    Hirotaka Nakajima, Kaiji Uchida, Takefumi Yoshida, Yoji Horii, Tetsu Sato, Zhang Luming, Satoshi Yamashita, Yasuhiro Nakazawa, Verdad C. Agulto, Makoto Nakajima, Brian K. Breedlove, Masahiro Yamashita, Hiroaki Iguchi, Shinya Takaishi

    ChemPhysChem     2022.10

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    DOI: 10.1002/cphc.202200618

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  13. Recent progress on unusual halogen-bridged Pd(III) chain compounds realized by weak ligand field and triple hydrogen bond approaches Reviewed

    Mohammad Rasel Mian, Masanori Wakizaka, Takefumi Yoshida, Hiroaki Iguchi, Shinya Takaishi, Masahiro Yamashita

    Coordination Chemistry Reviews   Vol. 475 ( 15 ) page: 214878   2022.10

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    DOI: https://doi.org/10.1016/j.ccr.2022.214878

  14. Benzenetriimide-Based Molecular Conductor with Antiferro- to Ferromagnetic Switching Induced by Structural Change of π-stacked Array. Reviewed International journal

    Shohei Koyama, Yoji Horii, Tetsu Sato, Shinya Takaishi, Norihisa Hoshino, Tomoyuki Akutagawa, Hiroaki Iguchi

    Chemphyschem : a European journal of chemical physics and physical chemistry   Vol. 23 ( 19 ) page: e202200322   2022.10

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    Benzenetriimide (BTI) is a promising building block for materials chemistry due to its characteristic 3-fold symmetry and redox properties, whereas little is known about its conductive and magnetic properties. In this study, we synthesized three charge-transfer complexes based on N,N',N''-trimethylbenzenetriimide (BTI-Me). One of the complexes contains isolated dimers of BTI-Me radical anion (BTI-Me⋅- ), while the other two have the infinite π-stacked array of BTI-Me with the formal charge of -0.5. The latter two complexes did not show metallic behavior but showed semiconducting behavior probably due to the characteristic insulation in one-dimensional electron system, so-called charge ordering and dimer-Mott insulation. The magnetic susceptibility of the complex in dimer-Mott state exhibits an unusual transition from antiferromagnetic to ferromagnetic spin states with the hysteresis loop of 15 K derived from the structural phase transition around 130 K. These properties were also supported by DFT calculations.

    DOI: 10.1002/cphc.202200322

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  15. Hydrogen Bonding Propagated Phase Separation in Quasi-Epitaxial Single Crystals: A Pd-Br Molecular Insulator Reviewed International coauthorship

    Takefumi Yoshida, Shinya Takaishi, Laurent Guérin, Tatsuhiro Kojima, Hiroyoshi Ohtsu, Masaki Kawano, Tatsuya Miyamoto, Hiroshi Okamoto, Kenichi Kato, Masaki Takata, Yuka Hosomi, Shoji Yoshida, Hidemi Shigekawa, Hisaaki Tanaka, Shin Ichi Kuroda, Hiroaki Iguchi, Brian K. Breedlove, Zhao Yang Li, Masahiro Yamashita

    Inorganic Chemistry   Vol. 61 ( 35 ) page: 14067 - 14074   2022.9

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    In condensed matter, phase separation is strongly related to ferroelasticity, ferroelectricity, ferromagnetism, electron correlation, and crystallography. These ferroics are important for nano-electronic devices such as non-volatile memory. However, the quantitative information regarding the lattice (atomic) structure at the border of phase separation is unclear in many cases. Thus, to design electronic devices at the molecular level, a quantitative electron-lattice relationship must be established. Herein, we elucidated a PdII-PdIV/PdIII-PdIIIphase transition and phase separation mechanism for [Pd(cptn)2Br]Br2(cptn = 1R,2R-diaminocyclopentane), propagated through a hydrogen-bonding network. Although the Pd···Pd distance was used to determine the electronic state, the differences in the Pd···Pd distance and the optical gap between Mott-Hubbard (MH) and charge-density-wave (CDW) states were only 0.012 Å and 0.17 eV, respectively. The N-H···Br···H-N hydrogen-bonding network functioned as a jack, adjusting the structural difference dynamically, and allowing visible ferroelastic phase transition/separation in a fluctuating N2gas flow. Additionally, the effect of the phase separation on the spin susceptibility and electrical conductivity were clarified to represent the quasi-epitaxial crystals among CDW-MH states. These results indicate that the phase transitions and separations could be controlled via atomic and molecular level modifications, such as the addition of hydrogen bonding.

    DOI: 10.1021/acs.inorgchem.2c02078

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  16. Trimetallic Mixture of Ni(III), Pd(III) and Au(III) Ions in a Molecule-Based Bromide-Bridged MX-Chain Compound Reviewed International coauthorship

    Masanori Wakizaka, Hashen Wu, Zhao-Yang Li, Hiroaki Iguchi, Shinya Takaishi, Masahiro Yamashita

    Bulletin of the Chemical Society of Japan   Vol. 95 ( 7 ) page: 1032 - 1038   2022.7

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    Multi-metallic inorganic alloy materials have attracted great attention recently. Additionally, molecule-based materials have wide designability in terms of their structures and electronic states. These are two different ideas. Here, we report the mixing of Pd(III) and Au(III) ions into a bromide-bridged molecular chain compound [Ni(chxn)2Br]Br2 (chxn: 1R,2R-diaminocyclo-hexane) to form an average formula of [Ni0.853Pd0.142Au0.005(chxn)2Br]Br2, which was synthesized by an electrochemical oxidation method. This trimetallic material is revealed to be a MottHubbard state semiconductor with a one-dimensional electronic system like that of [Ni(chxn)2Br]Br2, whereas it shows a smaller activation energy for conductivity than that of pristine [Ni(chxn)2Br]Br2. This work represents a fusion of the concepts of multi-metallic and molecule-based materials using a 1D compound.

    DOI: 10.1246/bcsj.20220137

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  17. Ni(III) Mott-Hubbard-like State Containing High-Spin Ni(II) in a Semiconductive Bromide-Bridged Ni-Chain Compound Reviewed

    Masanori Wakizaka, Mohammad Rasel Mian, Takefumi Yoshida, Tetsu Sato, Hisaaki Tanaka, Tatsuya Miyamoto, Hiroshi Okamoto, Shinya Takaishi, Hiroaki Iguchi, Masahiro Yamashita

    Inorganic Chemistry   Vol. 61 ( 25 ) page: 9504 - 9513   2022.6

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    Halogen-bridged linear chain metal complexes (MX-Chains) are fascinating compounds that have a quasi-one-dimensional (1D) electronic system. In this study, we synthesized the first Ni-based MX-Chain compound having hydroxy groups, i.e., [Ni(dabdOH)2Br]Br2·[Ni(dabdOHx)2Br]0.5·(2-PrOH)0.25·(MeOH)0.25(1·solvent, x = ∼0.6, dabdOH = (2S,3S)-2,3-diaminobutane-1,4-diol). Single-crystal X-ray diffraction revealed that the MX-Chains in 1·solvent formed sheets and single-chain structures in the superlattice. It suggested an MH-like state, whereas the polarized reflection and Raman spectra suggested a CDW-like state. Magnetic and electron spin resonance measurements revealed that both high-spin Ni(II) (∼15%) and low-spin Ni(III) (∼85%) sites are present in the chain structures, i.e., the metal sites show mixed valency. Therefore, we concluded that 1·solvent adopts an intermediate state between the MH and CDW states. Moreover, a single crystal of 1·solvent exhibited semiconductive characteristics along the chain direction. This finding represents a new structural and electronic state of 1D electronic systems as well as MX-Chains.

    DOI: 10.1021/acs.inorgchem.2c00473

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  18. Syntheses, Structures, and Properties of Coordination Polymers with 2,5-Dihydroxy-1,4-Benzoquinone and 4,4′-Bipyridyl Synthesized by In Situ Hydrolysis Method Reviewed

    Daiki Yamazui, Kaiji Uchida, Shohei Koyama, Bin Wu, Hiroaki Iguchi, Wataru Kosaka, Hitoshi Miyasaka, Shinya Takaishi

    ACS Omega   Vol. 7 ( 22 ) page: 18259 - 18266   2022.6

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    The coordination polymers (CPs) with binary ligands, including 2,5-dihydroxy-1,4-benzoquinone (H2DHBQ) and 4,4′-bipyridyl (bpy), were synthesized using in situ hydrolysis of 2,5-dimethoxy-1,4-benzoquinone (DMBQ). Three kinds of CPs were obtained depending on the metal ions. For M = Mn and Zn, a 1D zigzag chain structure with cis conformation (cis-1D-M) was obtained, whereas Co, Ni, and Cu compounds afforded a 2D net structure with trans conformation (trans-2D-M) with a 1D pore. A linear chain structure was also obtained for M = Cu. Magnetic susceptibility (χMT) at 300 K in cis-1D-Mn and trans-2D-Co was evaluated to be 4.421 and 2.950 cm3 K mol-1, respectively, indicating that both compounds are in the high-spin state. According to the N2 adsorption isotherms at 77 K, trans-2D-Ni showed microporosity with the BET surface area of 177 m2 g-1, whereas the isomorphic trans-2D-Co rarely adsorbed N2 at 77 K. This phenomenon was explained by the difference of diffusion kinetics of the adsorbent molecules, which was supported by the CO2 adsorption isotherms at 195 K. The optical band gaps of cis-1D-Mn, cis-1D-Zn, trans-2D-Co, and trans-2D-Ni were estimated to be 1.6, 1.8, 1.0, and 1.1 eV, respectively, by using UV-vis-NIR spectroscopy.

    DOI: 10.1021/acsomega.1c07077

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  19. An electrically conductive metallocycle: densely packed molecular hexagons with π-stacked radicals Reviewed

    Mengxing Cui, Ryuichi Murase, Yongbing Shen, Tetsu Sato, Shohei Koyama, Kaiji Uchida, Tappei Tanabe, Shinya Takaishi, Masahiro Yamashita, Hiroaki Iguchi

    Chemical Science   Vol. 13 ( 17 ) page: 4902 - 4908   2022.4

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    Intrinsically electron-conductive metallocycle was synthesized. π-Radicals play a key role in constructing π-stacked columns among molecular hexagons and achieving high electrical conductivity over 10<sup>−4</sup> S cm<sup>−1</sup> in polycrystalline pellet.

    DOI: 10.1039/d2sc00447j

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  20. Elucidating 2D Charge-Density-Wave Atomic Structure in an MX–Chain by the 3D-ΔPair Distribution Function Method** Reviewed

    Laurent Guérin, Takefumi Yoshida, Edoardo Zatterin, Arkadiy Simonov, Dmitry Chernyshov, Hiroaki Iguchi, Bertrand Toudic, Shinya Takaishi, Masahiro Yamashita

    ChemPhysChem   Vol. 23 ( 6 )   2022.3

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    Many solids, particularly low-dimensional systems, exhibit charge density waves (CDWs). In one dimension, charge density waves are well understood, but in two dimensions, their structure and their origin are difficult to reveal. Herein, the 2D charge-density-wave atomic structure and stabilization mechanism in the bromide-bridged Pd compound [Pd(cptn)2Br]Br2 (cptn=1R,2R-diaminocyclopentane) is investigated by means of single-crystal X-ray diffraction employing the 3D-Δpair distribution function (3D-ΔPDF) method. Analysis of the diffuse scattering using 3D-ΔPDF shows that a 2D-CDW is stabilized by a hydrogen-bonding network between Br− counteranion and the amine (NH2) group of the cptn in-plane ligand, and that 3D ordering is prevented due to a weak plane to plane correlation. We extract the effective displacements of the atoms describing the atomic structure quantitatively and discuss the stabilization mechanism of the 2D-CDW. Our study provides a method to identify and measure the key interaction responsible for the dimensionality and stability of the CDW that can help further progress of rational design.

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  21. Bromine Vapor Induced Continuous p- to n-Type Conversion of a Semiconductive Metal-Organic Framework Cu[Cu(pdt)<inf>2</inf>] Reviewed

    Shraddha Gupta, Haruki Tanaka, Tetsu Sato, Shen Ye, Brian K. Breedlove, Hiroaki Iguchi, Shinya Takaishi

    Inorganic Chemistry   Vol. 61 ( 10 ) page: 4414 - 4420   2022.3

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    Guest-promoted modulation of the electronic states in metal-organic frameworks (MOFs) has brought about a new field of interdisciplinary research, including host-guest chemistry and solid-state physics. Although there are dozens of studies on guest-promoted enhancement of the electrical conductivity properties, including stoichiometry, conductive carriers and structure-property relationships have been scarcely studied in detail. Herein, we studied the effects of continuous and controlled bromine vapor doping on structural, optical, thermoelectric, and semiconducting properties of Cu[Cu(pdt)2] (pdt = 2,3-pyrazinedithiolate) as a function of bromine stoichiometry. We demonstrated that the same material could act as both p- and n-type semiconductors by tuning the stoichiometry of Br doped in Brx@Cu[Cu(pdt)2], and a change in the charge-carrier type from holes in pristine MOF to electrons upon bromine vapor doping was observed. Bromine molecules acted as an oxidant, causing the selective oxidation of [CuII(pdt)2] in the host framework. In addition, a redox hopping pathway between the partially oxidized CuII/CuIII center contributed to the enhancement of the electrical conductivity of the MOF.

    DOI: 10.1021/acs.inorgchem.1c03933

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  22. Thermally induced electron-hole dissociation dynamics in quasi-one-dimensional bromo-bridged palladium(iii) Mott-insulator [Pd(en)<inf>2</inf>Br](Suc-C<inf>n</inf>)<inf>2</inf>·H<inf>2</inf>O (C<inf>n</inf>-Y = dialkylsulfosuccinate; n = 5 and 6) Reviewed

    Shohei Kumagai, Hiroaki Iguchi, Masahiro Yamashita, Shinya Takaishi

    Physical Chemistry Chemical Physics   Vol. 24 ( 13 ) page: 7978 - 7982   2022.3

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    Current-voltage characteristics and dielectric properties were studied in bromo-bridged one-dimensional compounds, [Pd(en)2Br](Suc-C5)2·H2O, exhibiting mixed-valence and averaged valence (MV-AV) phase transition. In the AV phase, clear nonlinear current-voltage characteristics were observed. This phenomenon was explained by the thermally induced electron-hole separation assisted by an electric field. This mechanism was supported by the dielectric properties of [Pd(en)2Br](Suc-Cn)2·H2O (n = 5 and 6).

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  23. Charge-density-wave Amplitude in Quasi-one-dimensional Halogen-bridged Palladium Complex, [Pd(<sup>15</sup>N-en)<sub>2</sub>Br](Suc-C<sub>5</sub>)<sub>2</sub>·H<sub>2</sub>O (Suc-C<sub>5</sub> = Dipentylsulfosuccinate), Estimated by <sup>15</sup>N Solid-state NMR Reviewed

    Shohei Kumagai, Hiroaki Iguchi, Masahiro Yamashita, Sadamu Takeda, Shinya Takaishi

    Chemistry Letters   Vol. 51 ( 3 ) page: 281 - 283   2022.3

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    Temperature dependency of the 15N CP-MAS NMR spectrum were examined in quasi-one-dimensional bromo-bridged palladium compound [Pd(en)2Br](Suc-C5)2 H2O (Suc-C5 = dipentylsulfosuccinate), which shows mixed-valence (MV) to averaged-valence (AV) phase transition. Single and double peaks were observed at lower and higher temperature sides from the phase transition temperature, reflecting that they are AVand MV states, respectively. Peak-to-peak interval in the spectra steadily decreased upon cooling, showing the charge-density-wave (CDW) amplitude decreased accompanied by approaching the AV state.

    DOI: 10.1246/cl.210804

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  24. Macro- and atomic-scale observations of a one-dimensional heterojunction in a nickel and palladium nanowire complex Reviewed

    Masanori Wakizaka, Shohei Kumagai, Hashen Wu, Takuya Sonobe, Hiroaki Iguchi, Takefumi Yoshida, Masahiro Yamashita, Shinya Takaishi

    Nature Communications   Vol. 13 ( 1 )   2022.3

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    Abstract

    The creation of low-dimensional heterostructures for intelligent devices is a challenging research topic; however, macro- and atomic-scale connections in one-dimensional (1D) electronic systems have not been achieved yet. Herein, we synthesize a heterostructure comprising a 1D Mott insulator [Ni(chxn)<sub>2</sub>Br]Br<sub>2</sub> (1; chxn = 1R-2R-diaminocyclohexane) and a 1D Peierls or charge-density-wave insulator [Pd(chxn)<sub>2</sub>Br]Br<sub>2</sub> (2) using stepwise electrochemical growth. It can be considered as the first example of electrochemical liquid-phase epitaxy applied to molecular-based heterostructures with a macroscopic scale. Moreover, atomic-resolution scanning tunneling microscopy images reveal a modulation of the electronic state in the heterojunction region with a length of five metal atoms (~ 2.5 nm), that is a direct evidence for the atomic-scale connection of 1 and 2. This is the first time that the heterojunction in the 1D chains has been shown and examined experimentally at macro- and atomic-scale. This study thus serves as proof of concept for heterojunctions in 1D electronic systems.

    DOI: 10.1038/s41467-022-28875-8

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  25. Interdigitated Pt-Br chains with π-stacking: an approach toward Robin-Day class I mixed valency in MX-chain complexes Reviewed

    Unjila Afrin, Kentaro Fuku, Mengxing Cui, Hiroaki Iguchi, Mohammad Rasel Mian, Ryo Nakanishi, Shinya Takaishi, Masahiro Yamashita

    Dalton Transactions   Vol. 50 ( 40 ) page: 14125 - 14129   2021.10

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    The first interdigitated MX-type chain complex with infinite π-stacked arrays was synthesized. The synchronization between a Pt-Br⋯ chain and π-stacking periodicities led to the longest M-X-M distance (6.6978(15) Å) and nil or negligible intervalence charge transfer, which is essential to realize the Robin-Day class I mixed valence state in MX chains.

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  26. Surface Ohmic Conductivity on a Mott Insulator Based on a One-dimensional Bromide-bridged Nickel(III) Complex

    Masanori Wakizaka, Hiroaki Iguchi, Shinya Takaishi, Masahiro Yamashita

    Chemistry - An Asian Journal   Vol. 16 ( 19 ) page: 2947 - 2951   2021.10

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    Ohmic contacts are of critical importance to improve the performance of semiconductor devices as well as those of low-dimensional materials. Halogen-bridged metal complexes (MX-Chains) are fascinating quasi-one-dimensional (1D) electronic materials. However, reports on the electrical characteristics of MX-Chains remain elusive. Herein, we report the electrical characteristics of single crystals of [Ni(chxn)2Br]Br2 (chxn: (1R,2R)-(−)-1,2-cyclohexanediamine), which is a 1D Mott insulator, using different probe arrangements. [Ni(chxn)2Br]Br2 was shown for the first time to exhibit Ohmic characteristics on the crystal surface, albeit that the conductivity behavior of the interior of the crystal is nonlinear due to the Joule heating effect. The current flow on the surface is shallow (a few micrometers in depth) despite the millimeter-scale crystal size; this phenomenon is strongly connected to its structural anisotropy. The Ohmic contact revealed in this work should be valuable for the application of MX-Chains as electronic devices in the near future.

    DOI: 10.1002/asia.202100637

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  27. Reversible hydrogen adsorption at room temperature using a molybdenum-dihydrogen complex in the solid state

    Kaiji Uchida, Naoki Kishimoto, Shin Ichiro Noro, Hiroaki Iguchi, Shinya Takaishi

    Dalton Transactions   Vol. 50 ( 36 ) page: 12630 - 12634   2021.9

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    Reversible H2storage under mild conditions is one of the most important targets in the field of materials chemistry. Dihydrogen complexes are attractive materials for this target because they possess moderate adsorption enthalpy as well as adsorption without cleavage of the H-H bond. In spite of these advantages, H2adsorption studies of dihydrogen complexes in the solid state are scarce. We herein present H2adsorption properties of the 16-electron precursor complex ([Mo(PCy3)2(CO)3]) in the solid state synthesized by two procedures. One is the direct synthesis under an Ar atmosphere (1), and the other is removal of the N2-adduct under vacuum (2).2showed ideal Langmuir type reversible ad/desorption of H2above room temperature, whereas1showed irreversible adsorption. The adsorption enthalpy of2was larger than that in THF solution. Using DFT calculation, this difference was explained by the absence of the agostic interaction in the solid state.

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  28. Electron-Conductive Metal-Organic Framework, Fe(dhbq)(dhbq = 2,5-Dihydroxy-1,4-benzoquinone): Coexistence of Microporosity and Solid-State Redox Activity

    Kazuki Kon, Kaiji Uchida, Kentaro Fuku, Shuntaro Yamanaka, Bin Wu, Daiki Yamazui, Hiroaki Iguchi, Hiroaki Kobayashi, Yoshiyuki Gambe, Itaru Honma, Shinya Takaishi

    ACS Applied Materials and Interfaces   Vol. 13 ( 32 ) page: 38188 - 38193   2021.8

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    Redox-active metal-organic frameworks (MOFs) have great potential for use as cathode materials in lithium-ion batteries (LIBs) with large capacities because the organic ligands can undergo multiple-electron redox processes. However, most MOFs are electrical insulators, limiting their application as electrode materials. Here, we report an electron-conductive MOF with a 2,5-dihydroxy-1,4-benzoquinone (dhbq) ligand, Fe(dhbq). This compound had an electrical conductivity of 5 × 10-6 S cm-1 at room temperature due to d-πinteractions between the Fe ion and the ligand and the permanent microporosity. Fe(dhbq) had an initial discharge capacity of 264 mA h g-1, corresponding to the two-electron redox process of dhbq.

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  29. Bluish Hydrochromic Naphthalenediimide Salt: Change of Hydrogen-bond Interactions as the New Mechanism of Vapochromism Reviewed

    Tappei Tanabe, Tetsu Sato, Kentaro Fuku, Kaiji Uchida, Tamon Yamauchi, Shinya Takaishi, Hiroaki Iguchi

    Chemistry Letters   Vol. 50 ( 8 ) page: 1479 - 1482   2021.8

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    Naphthalenediimide (NDI) is generally a yellowish to reddish chromophore, which shows vapochromism by the alternation of charge-transfer (CT) interactions at the NDI core. On the contrary, we discovered that the deprotonation of N,N - dihydroxy-1,4,5,8-naphthalenetetracarboxdiimide (NDI-(OH)2) gave a bluish organic salt with a hydrochromic property, which has been rare in conventional NDI derivatives. On the basis of the structural analyses and the calculation, the origin of the hydrochromism can be explained by the change of hydrogenbond interaction between the anionic imide group and H2O molecules.

    DOI: 10.1246/cl.210275

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  30. Ionic Charge-Transfer Liquid Crystals Formed by Alternating Supramolecular Copolymerization of Liquid π-Donors and TCNQ

    Hiroaki Iguchi, Hidenori Furutani, Nobuo Kimizuka

    Frontiers in Chemistry   Vol. 9   2021.3

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    A new family of liquid π-donors, lipophilic dihydrophenazine (DHP) derivatives, show remarkably high π-electron-donor property which exhibit supramolecular alternating copolymerization with 7,7,8,8-tetracyanoquinodimethane (TCNQ), giving ionic charge-transfer (ICT) complexes. The ICT complexes form distinct columnar liquid crystalline (LC) mesophases with well-defined alternating molecular alignment as demonstrated by UV-Vis-NIR spectra, IR spectra, and X-ray diffraction (XRD) patterns. These liquid crystalline ICT complexes display unique phase transitions in response to mechanical stress: the columnar ICT phase is converted to macroscopically oriented smectic-like mesophases upon applying shear force. Although there exist reports on the formation of ICT in the crystalline state, this study provides the first rational identification of ICT mesophases based on the spectroscopic and structural data. The liquid crystalline ICT phases are generated by strong electronic interactions between the liquid π-donors and solid acceptors. It clearly shows the significance of simultaneous fulfillment of strong π-donating ability and ordered self-assembly of the stable ICT pairs. The flexible, stimuli-responsive structural transformation of the ICT complexes offer a new perspective for designing processable CT systems with controlled hierarchical self-assembly and electronic structures.

    DOI: 10.3389/fchem.2021.657246

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  31. An unusual Pd(iii) oxidation state in the Pd-Cl chain complex with high thermal stability and electrical conductivity

    Mohammad Rasel Mian, Masanori Wakizaka, Takefumi Yoshida, Hiroaki Iguchi, Shinya Takaishi, Unjila Afrin, Tatsuya Miyamoto, Hiroshi Okamoto, Hisaaki Tanaka, Shin Ichi Kuroda, Brian K. Breedlove, Masahiro Yamashita

    Dalton Transactions   Vol. 50 ( 5 ) page: 1614 - 1619   2021.2

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    The Pd(iii) oxidation state is unusual and unstable since it strongly tends to disproportionate. We synthesized the quasi-one-dimensional (1D) halogen-bridged Pd(iii)-Cl complex [Pd(dabdOH) Cl]Cl (1-Cl; dabdOH = (2S,3S)-2,3-diaminobutane-1,4-diol) with multiple hydrogen bonds. From single-crystal X-ray diffraction, the bridging Cl ions were located at the midpoint of the Pd-Cl-Pd moieties in the 1D chains, indicating that the Pd ions are in a Pd(iii) average valence (AV) state. Moreover, bright spots for the Pd(iii) d orbitals in the upper Hubbard band above the Fermi level were observed every ∼5 Å using scanning tunnelling microscopy. These results clearly indicate that the Pd ions are in a Pd(iii) AV state in1-Cl. In addition,1-Clhas the highest thermal stability (470 K) among the Pd(iii) complexes reported and the highest electrical conductivity (0.6 S cm at 300 K) among the 1D Pd-Cl chains reported so far. 2 2 z2 − −1

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  32. Synthesis, structure and physical properties of (Trans-ttf-py<inf>2</inf>)<inf>1.5</inf>(pf<inf>6</inf>)·etoh: A molecular conductor with weak ch···n hydrogen bondings

    Shohei Koyama, Morio Kawai, Shinya Takaishi, Masahiro Yamashita, Norihisa Hoshino, Tomoyuki Akutagawa, Manabu Kanno, Hiroaki Iguchi

    Crystals   Vol. 10 ( 12 ) page: 1 - 11   2020.12

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    © 2020 by the authors. Licensee MDPI, Basel, Switzerland. The studies of crystal structures with hydrogen bonds have been actively pursued because of their moderate stabilization energy for constructing unique structures. In this study, we synthesized a molecular conductor based on 2,6-bis(4-pyridyl)-1,4,5,8-tetrathiafulvalene (trans-TTF-py2). Two pyridyl groups were introduced into the TTF skeleton toward the structural exploration in TTF-based molecular conductors involved by hydrogen bonds. In the obtained molecular conductor, (trans-TTF-py2)1.5(PF6)·EtOH, short contacts between the pyridyl group and the hydrogen atom of the TTF skeleton were observed, indicating that hydrogen bonding interactions were introduced in the crystal structure. Spectroscopic measurements and conductivity measurement revealed semiconducting behavior derived from π-stacked trans-TTF-py2 radical in the crystal structure. Finally, these results are discussed with the quantified hydrogen bonding stabilization energy, and the band calculation of the crystal obtained from density functional theory calculation.

    DOI: 10.3390/cryst10121081

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  33. Preliminary chemical reduction for synthesizing a stable porous molecular conductor with neutral metal nodes Reviewed

    Shohei Koyama, Tappei Tanabe, Shinya Takaishi, Masahiro Yamashita, Hiroaki Iguchi

    Chemical Communications   Vol. 56 ( 86 ) page: 13109 - 13112   2020.11

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    © The Royal Society of Chemistry. Preliminary chemical reduction of naphthalenediimide (NDI)-based organic ligands was applied to the synthesis of a porous molecular conductor (PMC) with neutral metal nodes (cobalt(ii) acetylacetonate). The obtained semiconductive PMC (PMC-2) was stable due to the neutral metal nodes, providing an advantage over electrochemical reduction. This journal is

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  34. Emergence of electrical conductivity in a flexible coordination polymer by using chemical reduction Reviewed

    Kentaro Fuku, Momoka Miyata, Shinya Takaishi, Takefumi Yoshida, Masahiro Yamashita, Norihisa Hoshino, Tomoyuki Akutagawa, Hiroyoshi Ohtsu, Masaki Kawano, Hiroaki Iguchi

    Chemical Communications   Vol. 56 ( 61 ) page: 8619 - 8622   2020.8

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    © The Royal Society of Chemistry. A flexible coordination polymer with a naphthalenediimide core exhibited reversible desorption-adsorption of solvent molecules and an enhancement of electrical conductivity (∼10-7 S cm-1) upon chemical reduction using hydrazine.

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  35. Conductive zigzag Pd(iii)-Br chain complex realized by a multiple-hydrogen-bond approach Reviewed

    Mohammad Rasel Mian, Unjila Afrin, Hiroaki Iguchi, Shinya Takaishi, Takefumi Yoshida, Tatsuya Miyamoto, Hiroshi Okamoto, Hisaaki Tanaka, Shin Ichi Kuroda, Masahiro Yamashita

    CrystEngComm   Vol. 22 ( 23 ) page: 3999 - 4004   2020.6

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    © The Royal Society of Chemistry 2020. Coexistence of zigzag structure and the uncommon Pd(iii) oxidation state in quasi-1D halogen-bridged metal complexes was realized in a conductive Br-bridged Pd chain complex, [Pd(dabdOH)2Br]SO4·3H2O (2), for the first time. Intra- and interchain hydrogen-bond networks among the (2S,3S)-2,3-diaminobutane-1,4-diol (dabdOH) ligand and SO42−and H2O molecules support this unusual structure and electronic state. The electrical conductivity of2reached 0.05 S cm−1at room temperature.

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  36. Simultaneous Spin‐Crossover Transition and Conductivity Switching in a Dinuclear Iron(II) Coordination Compound Based on 7,7′,8,8′‐Tetracyano‐ p ‐quinodimethane Reviewed

    Ryuta Ishikawa, Shuya Ueno, Shoei Nifuku, Yoji Horii, Hiroaki Iguchi, Yuji Miyazaki, Motohiro Nakano, Shinya Hayami, Shohei Kumagai, Keiichi Katoh, Zhao‐Yang Li, Masahiro Yamashita, Satoshi Kawata

    Chemistry – A European Journal   Vol. 26 ( 6 ) page: 1278 - 1285   2020.1

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  37. Front Cover: Simultaneous Spin‐Crossover Transition and Conductivity Switching in a Dinuclear Iron(II) Coordination Compound Based on 7,7′,8,8′‐Tetracyano‐ p ‐quinodimethane (Chem. Eur. J. 6/2020) Reviewed

    Ryuta Ishikawa, Shuya Ueno, Shoei Nifuku, Yoji Horii, Hiroaki Iguchi, Yuji Miyazaki, Motohiro Nakano, Shinya Hayami, Shohei Kumagai, Keiichi Katoh, Zhao‐Yang Li, Masahiro Yamashita, Satoshi Kawata

    Chemistry – A European Journal   Vol. 26 ( 6 ) page: 1161 - 1161   2020.1

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  38. Supramolecular self-assembled coordination architecture composed of a doubly bis(2-pyridyl)pyrazolate bridged dinuclear CuII complex and 7,7′,8,8′,-tetracyano-p-quinodimethanide radicals Reviewed

    Ryuta Ishikawa, Shunya Ueno, Hiroaki Iguchi, Brian K. Breedlove, Masahiro Yamashita, Satoshi Kawata

    CrystEngComm   Vol. 22 ( 2 ) page: 159 - 163   2020

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    <p>A tetranuclear Cu<sup>II</sup> complex composed of a doubly bpypz<sup>−</sup> bridged dinuclear Cu<sup>II</sup> complex with TCNQ˙<sup>−</sup> self-assembles into a 3D supramolecular coordination architecture <italic>via</italic> complementary weak coordination bonding and π-stacking interactions.</p>

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  39. Water-vapor Sensitive Spin-state Switching in an Iron(III) Complex with Nucleobase Pendants Making Flexible Hydrogen-bonded Networks Reviewed

    Kagesawa Koichi, Ichikawa Yuki, Iguchi Hiroaki, Breedlove Brian K, Li Zhaoyang, Yamashita Masahiro, Okazawa Atsushi, Kosaka Wataru, Miyasaka Hitoshi

    CHEMISTRY LETTERS   Vol. 48 ( 10 ) page: 1221 - 1224   2019.10

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    Sensitive chemo-switchable magnetic materials operating at room temperature are one of the most potential candidates for future chemical devices. Here, we report a discrete iron(III) complex that exhibits high-spin/low-spin switching, sensitive even to rare water-vapor atmosphere above room temperature. The transformation of the hydrogen-bonded network triggered by water molecules is closely associated with the spin-state changing.

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  40. Observation of charge bistability in quasi-one-dimensional halogen-bridged palladium complexes by X-ray absorption spectroscopy Reviewed

    Yoshida Takefumi, Takaishi Shinya, Kumagai Shohei, Iguchi Hiroaki, Mian Mohammad Rasel, Yamashita Masahiro

    DALTON TRANSACTIONS   Vol. 48 ( 31 ) page: 11628 - 11631   2019.8

  41. Organic-Inorganic Hybrid Gold Halide Perovskites: Structural Diversity through Cation Size Reviewed

    Murasugi Hideaki, Kumagai Shohei, Iguchi Hiroaki, Yamashita Masahiro, Takaishi Shinya

    CHEMISTRY-A EUROPEAN JOURNAL   Vol. 25 ( 42 ) page: 9885 - 9891   2019.7

  42. MX-type single chain complexes with an aromatic in-plane ligand: incorporation of aromatic interactions for stabilizing the chain structure Reviewed

    Afrin Unjila, Iguchi Hiroaki, Mian Mohammad Rasel, Takaishi Shinya, Yamakawa Hiromichi, Terashige Tsubasa, Miyamoto Tatsuya, Okamoto Hiroshi, Yamashita Masahiro

    DALTON TRANSACTIONS   Vol. 48 ( 22 ) page: 7828 - 7834   2019.6

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    <p>MX-type one-dimensional complexes containing only an aromatic in-plane ligand were synthesized for the first time.</p>

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  43. Porous Molecular Conductor: Electrochemical Fabrication of Through-Space Conduction Pathways among Linear Coordination Polymers Reviewed

    Qu Liyuan, Iguchi Hiroaki, Takaishi Shinya, Habib Faiza, Leong Chanel F, D'Alessandro Deanna M, Yoshida Takefumi, Abe Hitoshi, Nishibori Eiji, Yamashita Masahiro

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   Vol. 141 ( 17 ) page: 6802 - 6806   2019.5

  44. Smallest Optical Gap for Pt(II)-Pt(IV) Mixed-Valence Pt-Cl and Pt-Br Chain Complexes Achieved by Using a Multiple-Hydrogen-Bond Approach Reviewed

    Mian M. Rasel, Iguchi H, Takaishi S, Afrin U, Miyamoto T, Okamoto H, Yamashita M

    INORGANIC CHEMISTRY   Vol. 58 ( 1 ) page: 114 - 120   2019.1

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  45. Formation of pores and π-stacked columns in benzothienobenzothiophene-based linear coordination polymers Reviewed

    Shohei Koyama, Hiroaki Iguchi, Shinya Takaishi, Goulven Cosquer, Shohei Kumagai, Jun Takeya, Toshihiro Okamoto, Masahiro Yamashita

    Chemistry Letters   Vol. 48 ( 8 ) page: 756 - 759   2019

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    © 2019 The Chemical Society of Japan. Porous coordination polymer (PCP) with 2,7-bis(4-pyridyl)-[1]benzothieno[3,2-b][1]benzothiophene (BTBT-4py) ligands was synthesized. The PCP provides both pores and infinite π-stacked columns via the assemblies of linear coordination polymers. The overlap integrals between highest occupied molecular orbitals (HOMOs) of adjacent ligands largely depend on the conformation of BTBT cores. The PCP also showed drastic structural change induced by desolvation. This approach to introduce porosity in organic semiconductor crystal can lead to the development of molecular-based devices, such as porous field-effect transistor.

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  46. Structural Study of Bromide-Bridged Pd Chain Complex with Weak CH center dot center dot center dot O Hydrogen Bonds Reviewed

    Mian Mohammad Rasel, Iguchi Hiroaki, Miyata Momoka, Takaishi Shinya, Yamakawa Hiromichi, Terashige Tsubasa, Miyamoto Tatsuya, Okamoto Hiroshi, Yamashita Masahiro

    ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE   Vol. 644 ( 14 ) page: 646 - 651   2018.8

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  47. MX-Chain compounds with ReO4 counterions: Exploration of the robin-day class I-II boundary Reviewed

    Shohei Kumagai, Shinya Takaishi, Mengqi Gao, Hiroaki Iguchi, Brian K. Breedlove, Masahiro Yamashita

    Inorganic Chemistry   Vol. 57 ( 7 ) page: 3775 - 3781   2018.4

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    MX chains have been widely studied as a 1D mixed-valence system. Although there have been a large number of studies on the boundary between class II and III materials of the Robin-Day classification, there are few studies of compounds at the boundary between classes I and II. In this study, we synthesized a series of Pt- and Pd- MX-chain compounds with perrhenate counterions, [M(en)2][M(en)2X2](ReO4)4 (X = Br for M = Pd and X = Cl, Br, and I for M = Pt). All compounds were isostructural, and the metal-metal distances within the chain exceed 6 Å, which is the longest among MX-chain compounds thus far reported. For [Pt(en)2][Pt(en)2Cl2](ReO4)4 (PtCl), an intervalence charge transfer (IVCT) transition was observed in the UV region at 335 nm (3.7 eV), which is the shortest wavelength for the MX-chain compounds thus far reported, indicating that PtCl is the closest to the Robin-Day class I limit.

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  48. Correlation between Chemical and Physical Pressures on Charge Bistability in [Pd(en)2Br](Suc-Cn)2·H2O Reviewed

    Shohei Kumagai, Shinya Takaishi, Hiroaki Iguchi, Brian K. Breedlove, Takuya Kaneko, Hiroshi Ito, Shin-Ichi Kuroda, Masahiro Yamashita

    Inorganic Chemistry   Vol. 57 ( 1 ) page: 12 - 15   2018.1

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    Hydrostatic (physical) pressure effects on the electrical resistivity of a bromido-bridged palladium compound, [Pd(en)2Br](Suc-C5)2·H2O, were studied. The charge-density-wave to Mott-Hubbard phase transition temperature (TPT) steadily increased with pressure. By a comparison of the effects of the chemical and physical pressures on TPT, it was estimated that the chemical pressure by unit alkyl chain length, i.e., the number of carbon atoms in the alkyl chains within the counterion, corresponded to ca. 1.3 kbar of the physical pressure.

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  49. Three dimensional porous Hofmann clathrate [(MPtII)-Pt-II(CN)(4)](infinity) (M = Co, Ni) synthesized by using postsynthetic reductive elimination Reviewed

    Takuro Okamura, Bin Wu, Hiroaki Iguchi, Brian K. Breedlove, Masahiro Yamashita, Wataru Kosaka, Hitoshi Miyasaka, Shinya Takaishi

    CHEMICAL COMMUNICATIONS   Vol. 53 ( 48 ) page: 6512 - 6515   2017.6

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    We synthesized cyano-bridged three dimensional metal-organic frameworks [M-II(H2O)(2)Pt-IV(CN)(4)Br-2](infinity) center dot n(H2O) (1: M = Co, 2: M = Ni) with an NbO type topology. Although 1 and 2 have no accessible pores, these MOFs were found to undergo reductive elimination of the axial bromides on the Pt-IV ions as well as removal of water molecules upon heating to form porous [(MPtII)-Pt-II(CN)(4)](infinity) (1 ': M = Co, 2 ': M = Ni) with retention of their crystallinity.

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  50. Multiple-Hydrogen-Bond Approach to Uncommon Pd(III) Oxidation State: A Pd-Br Chain with High Conductivity and Thermal Stability Reviewed

    Mohammad Rasel Mian, Hiroaki Iguchi, Shinya Takaishi, Hideaki Murasugi, Tatsuya Miyamoto, Hiroshi Okamoto, Hisaaki Tanaka, Shin-ichi Kuroda, Brian K. Breedlove, Masahiro Yamashita

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   Vol. 139 ( 19 ) page: 6562 - 6565   2017.5

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    A Br-bridged Pd chain complex with the Pd ion in an uncommon +3 oxidation state, [Pd(dabdOH)(2)Br]Br-2 (3), was prepared using a new method involving multiple hydrogen bonds. The PdBr chain complex exhibited superior electrical conductivity and thermal stability. An in-plane ligand with an additional hydrogen donor group (hydroxy group), (2S,3S)-2,3-diaminobutane-1,4-diol (dabdOH), was used to create a multiple-hydrogen-bond network, which effectively shrinks the Pd-Br-Pd distance, stabilizing the Pd(III) state up to its decomposition temperature (443 K). 3 shows semiconducting behavior with quite high electrical conductivity (3-38 S cm(-1) at room temperature), which is 10(6) times larger than the previous record for analogous PdBr chains. Indeed, 3 is the most conductive MX-type chain complex reported so far. The precise positional control of ions via a multiple-hydrogen-bond network is a useful method for controlling the electronic states, thermal stability and conductivity of linear coordination polymers.

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  51. Self-assembly of Oligo(ethylene oxide)-linked Diammonium Ions with Polyoxometalates into Ordered Polyhedron Nanocrystals in Aqueous Media Reviewed

    Keita Ishiba, Daisuke Kichise, Hiroaki Iguchi, Masa-Aki Morikawa, Nobuo Kimizuka

    CHEMISTRY LETTERS   Vol. 46 ( 4 ) page: 430 - 433   2017.4

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    Self-assembly of Keggin-type polyoxometalates (POMs) with diammonium ions containing oligo(ethylene oxide) units form parallelepiped or octahedral nanocrystals. These structures are tunable depending on the chemical structure of the ammonium ions and preparative conditions. The ether linkages in these ammonium ions exert conformational flexibility, which is essential to achieve long-range regular molecular alignments in the nanocrystals.

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  52. Photoresponsive Nanosheets of Polyoxometalates Formed by Controlled Self-Assembly Pathways Reviewed

    Keita Ishiba, Takao Noguchi, Hiroaki Iguchi, Masa-aki Morikawa, Kenji Kaneko, Nobuo Kimizuka

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 56 ( 11 ) page: 2974 - 2978   2017.3

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    Anionic Keggin polyoxometalates (POMs) and ether linkage-enriched ammonium ions spontaneously self-assemble into rectangular ultrathin nanosheets in aqueous media. The structural flexibility of the cation is essential to form oriented nanosheets; as demonstrated by single-crystal X-ray diffraction measurements. The difference in initial conditions exerts significant influence on selecting for self-assembly pathways in the energy landscape. Photoillumination of the POM sheets in pure water causes dissolution of reduced POMs, which allowed site-specific etching of nanosheets using laser scanning microscopy. By contrast, photoetching was suppressed in aqueous AgNO3 and site-selective deposition of silver nanoparticles occurred as a consequence of electron transfer from the photoreduced POMs to Ag+ ions on the nanosheet surface.

    DOI: 10.1002/anie.201612473

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  53. Direct Observation of Ordered High-Spin-Low-Spin Intermediate States of an Iron(III) Three-Step Spin-Crossover Complex Reviewed

    Zhao-Yang Li, Hiroyoshi Ohtsu, Tatsuhiro Kojima, Jing-Wei Dai, Takefumi Yoshida, Brian K. Breedlove, Wei-Xiong Zhang, Hiroaki Iguchi, Osamu Sato, Masaki Kawano, Masahiro Yamashita

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 55 ( 17 ) page: 5184 - 5189   2016.4

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    A neutral mononuclear Fe-III complex [Fe-III(H-5-Br-thsa-Me)(5-Br-thsa-Me)]H2O (1; H-2-5-Br-thsa-Me=5-bromosalicylaldehyde methylthiosemicarbazone) was prepared that exhibited a three-step spin-crossover (SCO) with symmetry breaking and a 14K hysteresis loop owing to strong cooperativity. Two ordered intermediate states of 1 were observed, 4HS-2LS and 2HS-4LS, which exhibited reentrant phase-transition behavior. This study provides a new platform for examining multistability in SCO complexes.

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  54. Optically Visible Phase Separation between Mott-Hubbard and Charge-Density-Wave Domains in a Pd-Br Chain Complex Reviewed

    Takefumi Yoshida, Shinya Takaishi, Hiroaki Iguchi, Hiroshi Okamoto, Hisaaki Tanaka, Shin-ichi Kuroda, Yuka Hosomi, Shoji Yoshida, Hidemi Shigekawa, Tatsuhiro Kojima, Hiroyoshi Ohtsu, Masaki Kawano, Brian K. Breedlove, Laurent Guerin, Masahiro Yamashita

    CHEMISTRYSELECT   Vol. 1 ( 2 ) page: 259 - 263   2016.2

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    We synthesized a bromo-bridged Pd complex, which underwent as lowering the temperature a charge-density-wave (CDW) to Mott-Hubbard (MH) phase transition, as confirmed by using X-ray diffraction analysis, ESR, FT-IR and Raman spectroscopies. The complex showed a phase-separation phenomenon with a striped pattern over a wide temperature range, and domain propagation was observed using an optical microscope. Moreover, we observed changes in the local electronic state accompanying the phase transition by using scanning tunneling microscopy (STM).

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  55. Charge-bistable Pd(III)/Pd(II,IV) coordination polymers: phase transitions and their applications to optical properties Reviewed

    Shohei Kumagai, Shinya Takaishi, Hiroaki Iguchi, Masahiro Yamashita

    DALTON TRANSACTIONS   Vol. 44 ( 18 ) page: 8590 - 8599   2015

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    Quasi-one-dimensional halogen-bridged Pt, Pd, and Ni complexes (MX chains) are a family of materials with potential charge bistability: M(II)-M(IV) mixed valence charge-density-wave (CDW) and M(III) averaged valence Mott-Hubbard (MH) states can form. However, until recently, no examples of MX chains showing charge bistability have been reported. Charge-bistable Pd MX chains, [Pd(en)(2)Br](Y1-C-n)(2)center dot H2O (en = 1,2-diaminoethane; Y1-C-n = dialkyl 2-sulfosuccinate; n = the number of carbon atoms in alkyl chains) and [Pd(en)(2)Br](Y2-C-n)(2)center dot H2O (Y2-C-n = dialkyl alpha-sulfomalonate), both of which showed phase transitions between Pd(III) MH and Pd(II,IV) CDW states, were prepared by utilizing chemical pressure. In addition, [Pd(en)(2)Br](Y1-C-n)(2) center dot H2O underwent pressure- and photo-induced MH-CDW phase transitions. [Pd(en)(2)Br](Y2-C-n)(2)center dot H2O has a higher transition temperature, i.e., higher stability of the MH state, than [Pd(en)(2)Br](Y1-C-n)(2)center dot H2O does due to the difference in the crystal packing. The recent progress will lead to new pressure sensing and optical switching devices.

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  56. Continuous Control of Optical Gaps in Quasi-One-Dimensional Bromide-Bridged Platinum Complexes by Utilizing Chemical Pressure Reviewed

    Shohei Kumagai, Hiroaki Iguchi, Shinya Takaishi, Brian K. Breedlove, Masahiro Yamashita, Hiroyuki Matsuzaki, Hiroshi Okamoto, Kenichi Kato, Masaki Takata

    INORGANIC CHEMISTRY   Vol. 53 ( 21 ) page: 11764 - 11769   2014.11

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    The optical gap in a series of bromo-bridged platinum chain complexes, [Pt(en)(2)Br](C-n-Y)(2).H2O (en = ethylenediamine; Cn-Y = dialkyl sulfosuccinate; n = the number of carbon atoms), was controlled by using chemical pressure. From the single-crystal structure, [Pt(en)(2)Br](C-6-Y)(2).H2O is in a mixed-valence state at 200 K. In addition, Pt-Pt distances decreased with an increase in n or with a decrease in the temperature. Continuous decreases in the optical gaps upon cooling were observed for n = 5, 7. The smallest gap of 1.20 eV was observed for n = 7 at 50 K. For n = 12, the complex was still in a mixed-valence state at 5 K, although the Pt-Pt distance was quite short. This is probably because of the energetic mismatch between 5dz(2) orbitals of the Pt ions and 4pz orbitals of the Br ions.

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  57. Solid-State Electrochemistry of a Semiconducting MMX-Type Diplatinum Iodide Chain Complex Reviewed

    Hiroaki Iguchi, Ayman Nafady, Shinya Takaishi, Masahiro Yamashita, Alan M. Bond

    INORGANIC CHEMISTRY   Vol. 53 ( 8 ) page: 4022 - 4028   2014.4

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    Electron-transfer-facilitated dissolution, ion insertion, and desorption associated with an MMX-type quasi-one-dimensional iodide-bridged dinuclear Pt complex (MMX chain) have been investigated for the first time. K-2(NC3N)-[Pt-2(pop)(4)1]center dot 4H(2)O (1) (NC3N2+ = (H3NC3H6NH3)(2+); pop = P2H2O52-) is a semiconductor with a three-dimensional coordination-bond and hydrogen-bond network included in the chain. The cyclic voltammetry of 1 was studied by using 1-modified electrodes in contact with acetonitrile solutions containing electrolyte. The chemical reversibility for oxidation of 1 depended on the electrolyte cation size, with large cations such as tetrabutylammonium (Bu4N+) being too large to penetrate the pores formed by the loss of K+ and NC3N2+ upon oxidation. The potential for reduction of 1 decreased as the cation size increased. The presence of the acid induced additional well-defined processes but with gradual solid dissolution, attributed to the breaking of the coordination-bond networks.

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  58. Recent Progress in MMX-Chain Complexes: Unique Electronic States and Characteristics Developed by Introducing Binary Countercations Invited Reviewed

    Hiroaki Iguchi, Shinya Takaishi, Masahiro Yamashita

    CHEMISTRY LETTERS   Vol. 43 ( 1 ) page: 69 - 79   2014.1

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    MMX-Type quasi-one-dimensional iodide-bridged diplatinum complexes (MMX chains) provide various electronic states and attractive physical properties. In this review, we summarize the recent progress in MMX chains consisting of pyrophosphite (pop) ligands. The MMX chains with binary countercations, which have short Pt-I-Pt distance and robust frameworks, form a new electronic state. They show reversible dehydration-rehydration accompanied by the change of electronic states and electrical conductivity. Relatively high electrical conductivity in the MMX chains with binary countercations enables us to investigate the negative differential resistance (NDR) and electrochemical characteristics in the solid state for the first time in MMX chains.

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  59. Predominance of covalency in water-vapor-responsive MMX-type chain complexes revealed by I-129 Mossbauer spectroscopy Reviewed

    Hiroaki Iguchi, Shinji Kitao, Makoto Seto, Shinya Takaishi, Masahiro Yamashita

    DALTON TRANSACTIONS   Vol. 43 ( 23 ) page: 8767 - 8773   2014

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    I-129 Mossbauer spectroscopy was applied to water-vapor-responsive MMX-type quasi-one-dimensional iodide-bridged Pt complexes (MMX chains)in order to investigate their electronic state quantitatively. Two sets of octuplets observed in K-2(H3NC3H6NH3)[Pt-2(pop)(4)I]center dot 4H(2)O (2 center dot 4H(2)O)and one octuplet observed in K-2(cis-H(3)NCH(2)CHvCHCH(2)NH(3))[Pt-2(pop)(4)I]center dot 4H(2)O (1 center dot 4H(2)O)and dehydrated complexes (1 and 2)indicate a unique alternating charge-polarization + charge-density-wave (ACP + CDW)electronic state and a charge-density-wave (CDW)electronic state, respectively. These spectra correspond to their crystal structure and the change of electronic states upon dehydration. Since these complexes consist of an alternating array of positively charged and negatively charged layers, the charge on the iodide ion (rho(IS))was discussed on the basis of the isomer shift (IS). The rho(IS) of the water-vapor-responsive MMX chains was mainly -0.13 to -0.21, which are the smallest of all MMX chains reported so far. Hence, it indicates that the negative charge on the iodide ion is strongly donated to the Pt ion in these complexes. This covalent interaction predominates in the ACP + CDW state as well as in the CDW state. Therefore, the ACP + CDW state is in fact the CDW state with the ACP-type lattice distortion. Because the rho(IS) became smaller with the decreasing Pt-I-Pt distance, it can be concluded that the covalent interaction plays an important role in determining the electronic states of the MMX chains with pop (= P2H2O52-)ligands.

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  60. Negative Differential Resistance in MX- and MMX-Type Iodide-Bridged Platinum Complexes Reviewed

    Hiroaki Iguchi, Shinya Takaishi, Deli Jiang, Jimin Xie, Masahiro Yamashita, Atsuko Uchida, Hitoshi Kawaji

    INORGANIC CHEMISTRY   Vol. 52 ( 24 ) page: 13812 - 13814   2013.12

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    Negative differential resistance (NDR) was discovered in MX- and MMX-type iodide-bridged platinum complexes for the first time. The low resistance of the complex observed under the large current cannot be explained only by the Joule heat. The intrinsic charge-ordering states are considered to play an important role in the NDR of these compounds.

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  61. Controlling the Electronic States and Physical Properties of MMX-Type Diplatinum-Iodide Chain Complexes via Binary Countercations Reviewed

    Hiroaki Iguchi, Shinya Takaishi, Brian K. Breedlove, Masahiro Yamashita, Hiroyuki Matsuzaki, Hiroshi Okamoto

    INORGANIC CHEMISTRY   Vol. 51 ( 18 ) page: 9967 - 9977   2012.9

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    MMX-type quasi-one-dimensional iodide-bridged dinuclear Pt complexes (MMX chains) with binary countercations show a new alternating charge-polarization + charge-density-wave (ACP+CDW) electronic state and reversible switching of the electronic states and physical properties upon dehydration and rehydration process. By comparing several MMX chains with various binary countercations with previous chains, we found that the short backbone of the aliphatic diammonium ion was indispensable for realizing the ACP+CDW state because it induces a 2-fold periodicity along the chain axis via twisting of the ligands. Moreover, the reversibility of the changes in the structure and electrical conductivity upon dehydration and rehydration depend on the length of aliphatic diammonium ion. Short diammonium ions support a robust framework, which undergoes reversible structural changes. On the other hand, long and bent aliphatic diammonium ions weaken the framework, which causes partial degradation of the crystal and a decrease in the electrical conductivity when the structure changes. However, the decrease in the activation energy of the electrical conductivity after the dehydration process is independent of the robustness of the complex, indicating that the orbital overlap in MMX chains with binary countercations increases upon dehydration. Controllable electronic states and physical properties provide a platform for designing the multifunctional materials based on MMX chains.

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  62. Electron spin resonance observation of dehydration-induced spin excitations in quasi-one-dimensional iodo-bridged diplatinum complexes Reviewed

    Hisaaki Tanaka, Shin-ichi Kuroda, Hiroaki Iguchi, Shinya Takaishi, Masahiro Yamashita

    PHYSICAL REVIEW B   Vol. 85 ( 7 )   2012.2

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    Electron spin resonance (ESR) measurements have been performed on a series of quasi-one-dimensional iodo-bridged diplatinum complexes K-2[C3H5R(NH3)(2)][Pt-2(pop)(4)I]center dot 4H(2)O (pop = P2H2O52-; R = H, CH3, or Cl), where dehydration/ rehydration of the crystalline water switches the electronic state reversibly with retention of single crystallinity. We have observed a nonmagnetic nature in as-grown samples, whereas in the dehydrated samples, a clear enhancement of the spin susceptibility has been observed above similar to 80 K with the activation energy ranging 50-60 meV. The activated spins originate from isolated Pt3+ state on the chain, as confirmed from the principal g values. Concomitantly, the ESR linewidth exhibits a prominent motional narrowing, suggesting that the activated Pt3+ spins are mobile solitons generated in the doubly degenerate charge-density-wave states of the dehydrated salts.

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  63. Novel Countercation in MMX-Type Mixed-Valence Chain Compound: Coexistence of Neutral and Protonated Amino Substituents Reviewed

    Hiroaki Iguchi, Deli Jiang, Jimin Xie, Shinya Takaishi, Masahiro Yamashita

    POLYMERS   Vol. 3 ( 4 ) page: 1652 - 1661   2011.12

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    The first MMX-type quasi-one-dimensional (Q1D) Pt chain complex (MMX chain) that contains a mono-protonated diamine as countercation, {o-(H3NC6H4NH2)}(4)[Pt-2(pop)(4)I]center dot H2O (pop = P2H2O52-), was synthesized. According to the crystal structural analysis, -NH2 group was hydrogen-bonded to either lattice H2O molecule or -NH3+ group in addition to typical hydrogen bond between -NH3+ group and pop ligand. To control the partial deprotonation of the countercation will be an important method for achieving the high-conductive MMX-chain polymer by the hole doping.

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  64. Water-Vapor-Induced Reversible Switching of Electronic States in an MMX-Type Chain Complex with Retention of Single Crystallinity Reviewed

    Hiroaki Iguchi, Shinya Takaishi, Hitoshi Miyasaka, Masahiro Yamashita, Hiroyuki Matsuzaki, Hiroshi Okamoto, Hisaaki Tanaka, Shin-ichi Kuroda

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   Vol. 49 ( 3 ) page: 552 - 555   2010

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  65. Direct Synthesis and Crystal Structure of Dehydrated State in Vapochromic MMX-type Quasi-One-Dimensional Iodide-Bridged Platinum Complexes Reviewed

    Hiroaki Iguchi, Shinya Takaishi, Takashi Kajiwara, Hitoshi Miyasaka, Masahiro Yamashita, Hiroyuki Matsuzaki, Hiroshi Okamoto

    JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS   Vol. 19 ( 1 ) page: 85 - 90   2009.3

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    The dehydrated vapochromic 1D coordination polymer, (H(3)NC(4)H(8)NH(3))(2)[Pt(2)(pop)(4)I] (1) was synthesized directly from methanol solution. Although vapochromic 1 center dot A 4H (2) O has been synthesized, dehydrated high-temperature structure has never been determined because of lowering the quality of crystal by dehydration. The crystal structure of 1 was determined by X-ray crystal structure analysis, and we confirmed that it was identical to the dehydrated high-temperature structure of 1 center dot A 4H (2) O by comparing the powder X-ray diffraction (XRD) patterns. The Pt-I-Pt distance (d(Pt-I-Pt)) of compound 1 center dot A 4H (2) O was shortened for approximately 1.1 A... by desorption of water to form compound 1, accompanied with phase transition in electronic states. The other crystal including methanol molecule as lattice solvent, 1 center dot A 2MeOH, was also obtained as by-product. The synthesis from various kinds of organic solvent has the great potential to develop the field of vapochromism accompanying phase transition of electronic state.

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  66. Mixed Charge-Ordering State of MMX-Type Quasi-One-Dimensional Iodide-Bridged Platinum Complexes with Binary Countercations Reviewed

    Hiroaki Iguchi, Shinya Takaishi, Takashi Kajiwara, Hitoshi Miyasaka, Masahiro Yamashita, Hiroyuki Matsuzaki, Hiroshi Okamoto

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   Vol. 130 ( 52 ) page: 17668 - +   2008.12

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    A new charge-ordering (CO) state in quasi-1D iodide-bridged dinuclear Pt complexes (MMX-chains) was developed by introducing two different kinds of countercations. From crystal structure analysis, K(2)(H(3)NCH(2)CHMeCH(2)NH(3))[Pt(2)(pop)(4)I]center dot 4H(2)O (pop = P(2)H(2)O(5)(2-)) had structural features of both ACP (alternating charge-polarization) and CDW (charge-density-wave) states. Therefore, this new CO state was named ACP+CDW state. Remarkably, the structure was three dimensionally ordered, which was verified by the strong superlattice reflections observed in an X-ray oscillation photograph. Using polarized Raman and (31)P MAS NMR spectroscopies, it was shown that there were two different Pt(2) units and four inequivalent P atoms, respectively. These results agreed with the crystal structure analysis and supported the presence of the ACP+CDW state.

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  67. Three-dimensionally ordered CDW state in quasi-one-dimensional iodo-bridged dinuclear platinum mixed-valence compounds, A(4)[Pt2I(POP)(4)]center dot nH(2)O (A = aromatic ammonium cations) Reviewed

    Satoshi Matsunaga, Kouichi Takizawa, Daisuke Kawakami, Hiroaki Iguchi, Shinya Takaishi, Takashi Kajiwara, Hitoshi Miyasaka, Masahiro Yamashita, Hiroyuki Matsuzaki, Hiroshi Okamoto

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY   ( 21 ) page: 3269 - 3273   2008.7

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    Linear-chain iodo-bridged dinuclear Pt mixed-valence compounds with aromatic ammonium countercations, A(4)[Pt2I(POP)(4)]center dot nH(2)O [POP = P2O5H22-, A = benzyl ammonium (n = 2; 1), anilinium (n = 2; 2), and p-methoxy anilinium (n = 2; 3)], that have three-dimensionally ordered structures were synthesized. In the case of 1-3 the aromatic ammonium countercations were located between neighboring Pt chains and stacked in 1D columns. pi-pi Interactions between the phenyl rings and hydrogen bonds between the -NH3+ moieties and the oxygen atoms of the pop ligand link the Pt chains together, thus giving rise to a three-dimensionally ordered CDW state. This is the first observation of this phenomenon in compounds of this type. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).

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  68. Electronic structure of Co-III doped bromo-bridged Ni complexes, [Ni1-xCox(chxn)(2)Br]Br-2 Reviewed

    Jimin Xie, Hashen Wu, Daisuke Kawakami, Hiroaki Iguchi, Shinya Takaishi, Masahiro Yamashita, Hiroyuki Matsuzaki, Hiroshi Okamoto, Hisaaki Tanaka, Shin-Chi Kuroda

    INORGANIC CHEMISTRY   Vol. 47 ( 6 ) page: 1949 - 1952   2008.3

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    This article describes the electronic structure of the Co-III doped Br bridged Ni-III complexes, [Ni(1-x)Co(x)chxn)(2)Br]Br-2 (x = 0.01, 0.02, 0.05, and 0.11) by using a optical spectroscopy, scanning tunneling microscopy (STM), and electron spin resonance spectroscopy. In the optical reflectivity spectrum, the new band was formed at about 0.5 eV, which is reasonably recognized as the d(z)2 band of doped Co-III ions. In the STM images of [Ni1-x,Co-x(chxn)(2)Br]Br-2, the bright spots attributable to the tunnel current from the Fermi level of the STM tip to the conduction band of the sample were observed. In addition, some brighter spots were also observed. Because the number of the brighter spots is in good agreement with that of doped Co species, the brighter spots can be assigned to doped Co-III sites. These are reasonably explained by the tunnel current from the Fermi level of the tip to the d(z)(2) band of Co-III. The Curie spin concentration was gradually increased with increasing Co-III ions, which is explained by the scissions of the S = 1/2 1D antiferromagnetic chains.

    DOI: 10.1021/ic7012232

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Books 1

  1. Material Designs and New Physical Properties in MX- and MMX-Chain Compounds

    Masahiro Yamashita, Hiroshi Okamoto, Eds( Role: Joint author ,  第10章(POP-Type MMX-Chain Compounds with Binary Countercations and Vapochromism) pp191-214)

    Springer  2013.1  ( ISBN:9783709113165

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MISC 14

  1. Recent progress on unusual halogen-bridged Pd(III) chain compounds realized by weak ligand field and triple hydrogen bond approaches Reviewed

    Mohammad Rasel Mian, Masanori Wakizaka, Takefumi Yoshida, Hiroaki Iguchi, Shinya Takaishi, Masahiro Yamashita

    Coordination Chemistry Reviews   Vol. 475   2023.1

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    The development of new halogen-bridged Pd chain complexes with molecular precision offers a promising strategy to stabilize Pd(III) ions, which are being considered as future optical, magnetic, dielectric, and conducting materials. More recently, uncommon and rare electronic states of Pd(III) ions in halogen-bridged chain complexes have been reported. In these systems, four different designed strategies have been adopted to stabilize Pd(III) oxidation states to date. This review focuses on the new strategies for the realization of Pd(III) halogen-bridged metal complexes (MX-Chains) using (1) weak ligand field and (2) triple hydrogen bond approaches. The resulting MX-Chains show clear evidence of the Pd(III) averaged-valence (AV) state rather than the conventional Pd(II)/Pd(IV) mixed-valence (MV) state. The relationships between the molecular structures, electronic states, and properties of these MX-Chains strongly depend on the in-plane ligands, counteranions and their surrounding environments. Furthermore, Pd(III) states have been found in the MX-Chains even above room temperature. Understanding and controlling the Pd(III) states in halogen-bridged chain complexes is a critical issue for development of next-generation devices, such as molecular electrical nano-wires. Overall, this review establishes halogen-bridged Pd(III) complexes as highly effective solid-state materials and provides detailed insight into their structure–property relationships, laying the groundwork for future developments in this new class of advanced materials.

    DOI: 10.1016/j.ccr.2022.214878

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  2. ナノ細孔を有する分子性導体の開発 Reviewed

    井口弘章

    日本化学会有機結晶部会ニュースレター   Vol. 52   page: 3 - 4   2022.8

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  3. 一次元半導体のヘテロ接合に成功-原子サイズの半導体デバイスの実現

    脇坂聖憲, 脇坂聖憲, WU Hashen, 井口弘章, 井口弘章, 山下正廣, 高石慎也

    化学   Vol. 77 ( 6 )   2022

  4. Simultaneous Spin‐Crossover Transition and Conductivity Switching in a Dinuclear Iron(II) Coordination Compound Based on 7,7′,8,8′‐Tetracyano‐ p ‐quinodimethane Invited Reviewed International coauthorship International journal

    Ryuta Ishikawa, Shuya Ueno, Shoei Nifuku, Yoji Horii, Hiroaki Iguchi, Yuji Miyazaki, Motohiro Nakano, Shinya Hayami, Shohei Kumagai, Keiichi Katoh, Zhao‐Yang Li, Masahiro Yamashita, Satoshi Kawata

    Chemistry – A European Journal   Vol. 26 ( 6 ) page: 1165 - 1165   2020.1

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  5. 安定な高伝導性ナノワイヤー金属錯体 ―多重水素結合によるPd(III)状態の安定化

    IGUCHI Hiroaki, MIAN Mohammad Rasel, TAKAISHI Shinya, YAMASHITA Masahiro

    Kagaku   Vol. 73 ( 3 ) page: 19 - 22   2018.3

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  6. スーパーキャパシタの新材料 高伝導性MOFが拓く新たな可能性

    Hiroaki Iguchi

    化学   Vol. 72 ( 7 ) page: 60 - 61   2017.7

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  7. POP-type MMX-chain compounds with binary countercations and vapochromism

    Hiroaki Iguchi, Shinya Takaishi, Masahiro Yamashita

    Material Designs and New Physical Properties in MX- and MMX-Chain Compounds   Vol. 9783709113172   page: 207 - 230   2013.6

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    Pyrophosphito-bridged diplatinum complex is one of the most studied dinuclear complexes in a paddle-wheel structure. The chemistry of pyrophosphito-bridged diplatinum complex began at the discovery of the Pt(II)-Pt(II) complex, K4[Pt2(pop)4]·2H2O (pop = P2H2O 5 2-) by Roundhill et al. in 1977 [1]. Since [Pt2(pop)4]4- shows intense long-lived phosphorescence, photochemistry and excited-state chemistry of [Pt2(pop)4]4- has been attracted much attention (see following early reviews and references therein [2, 3]). Although no chemical bond exist between two Pt(II) atoms in the ground state, 5dσ → 6pσ transition should induce the bonding character between them. This excited-state structure has been confirmed by several optical methods [4-9]. The excited state of [Pt2(pop)4]4- is powerful one-electron reductant, therefore, it can be used as a photochemical catalyst for converting ethanol to acetaldehyde and hydrogen [10] and for the transfer hydrogenation of alkenes and alkynes [11, 12]. The Pt(III)-Pt(III) complex, [Pt2(pop)4H2]4-, is the active species of the catalytic reaction [13].

    DOI: 10.1007/978-3-7091-1317-2_10

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  8. 結晶水の可逆的脱離・吸着能を有するMMX型擬一次元ヨウ素架橋白金錯体の電子状態

    井口弘章, 高石慎也, 宮坂等, 山下正廣, 田中久暁, 伊東裕, 黒田新一, 北尾真司, 瀬戸誠, 松崎弘幸, 岡本博

    日本化学会講演予稿集   Vol. 91st ( 2 ) page: 193   2011.3

  9. 23pRB-4 Physical property and electronic state of molecular conductor based on naphthalenediimide derivative and quasi-one-dimensional Br-bridged lead complex

    Iguchi Hiroaki, Takaishi Shinya, Kubo Kazuya, Miyasaka Hitoshi, Yamashita Masahiro, Yamamoto Takashi, Tanaka Hisaaki, Kuroda Shin-ichi, Tajima Akiko, Kato Reizo

    Meeting abstracts of the Physical Society of Japan   Vol. 65 ( 2 ) page: 213 - 213   2010.8

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  10. 23pRB-5 Electrical conduction of halogen-bridged binuclear metal complex with binary counter-cation under pressure-H_2O desorption effect

    Ito H., Kanbe Y., Tanaka H., Kuroda S., Iguchi H., Takaishi S., Yamashita M.

    Meeting abstracts of the Physical Society of Japan   Vol. 65 ( 2 ) page: 781 - 781   2010.8

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  11. 23pRB-5 Electrical conduction of halogen-bridged binuclear metal complex with binary counter-cation under pressure : H_20 desorption effect

    Ito H., Kanbe Y., Tanaka H., Kuroda S., Iguchi H., Takaishi S., Yamashita M.

    Meeting abstracts of the Physical Society of Japan   Vol. 65 ( 2 ) page: 214 - 214   2010.8

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  12. 27aYF-4 ESR observations of cation substitution effects in halogen-bridged binuclear metal complex

    Tanaka H., Kuroda S., Iguchi H., Takaishi S., Yamashita M.

    Meeting abstracts of the Physical Society of Japan   Vol. 64 ( 1 ) page: 806 - 806   2009.3

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  13. 21aTC-2 ESR observations of the H_2O adsorption/desorption effects in halogen-bridged binuclear metal complex K_2[H_3NC_3H_6NH_3]Pt_2(pop)_4I・4H_2O

    Tanaka H., Takashima M., Kuroda S., Iguchi H., Takaishi S., Yamashita M.

    Meeting abstracts of the Physical Society of Japan   Vol. 63 ( 2 ) page: 743 - 743   2008.8

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  14. 23aTF-5 ESR studies of the halogen-bridged binuclear metal complex with binary counteractions exhibiting alternate-charge-polarization state

    Tanaka H., Takashima M., Kuroda S., Iguchi H., Takaishi S., Yamashita M.

    Meeting abstracts of the Physical Society of Japan   Vol. 63 ( 1 ) page: 795 - 795   2008.2

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Presentations 66

  1. ナノ細孔を有する分子性導体の開発 Invited

    井口 弘章

    ISSPワークショップ「デバイス活用で臨む有機伝導体の未来」  2024.3.27 

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    Event date: 2024.3

    Presentation type:Oral presentation (invited, special)  

  2. 電子状態の自在制御を目指した多孔性分子導体の開発 Invited

    井口 弘章

    日本化学会第104春季年会  2024.3.18 

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    Event date: 2024.3

    Presentation type:Oral presentation (invited, special)  

  3. ナノ細孔とπ積層骨格を併せ持つ導電性配位高分子の開発

    井口弘章、Qu Liyuan、田邉辰平

    第6回固体化学フォーラム研究会  2024.1.16 

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    Event date: 2024.1

    Presentation type:Poster presentation  

  4. 導電性π共役骨格を有するMOFの開発

    井口 弘章

    令和5年度 第1回 「⾼密度共役の科学」 若⼿会合宿  2023.12.16 

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    Event date: 2023.12

    Presentation type:Poster presentation  

  5. Controlling Electronic Properties of Coordination Polymers by Guest Desorption Invited International conference

    Mini-Symposium on Innovative Visualization for Materials Science  2023.12.11 

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    Event date: 2023.12

    Presentation type:Oral presentation (invited, special)  

  6. Porous Molecular Conductors Constructed from Naphthalenediimide-based Coordination Networks and Metallocycles Invited International conference

    Hiroaki Iguchi, Tappei Tanabe, Mengxing Cui, Ryuichi Murase, Liyuan Qu, Shinya Takaishi, Masahiro Yamashita

    14th Japan-China Joint Symposium on Conduction and Photoconduction in Organic Solids and Related Phenomena  2023.12.7 

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    Event date: 2023.12

    Presentation type:Oral presentation (invited, special)  

  7. Porous Molecular Conductors: Electron-Conductive Coordination Networks Assembled by π-Radicals Invited International conference

    Hiroaki Iguchi

    Functional Porous Materials & Reticular Chemistry of Porous Polymers Workshop  2023.11.18 

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    Event date: 2023.11

    Presentation type:Oral presentation (invited, special)  

  8. Porous Molecular Conductors: Self-Assembly of Coordination Networks by π-Radicals Invited

    Hiroaki Iguchi

    4th IRTG Münster–Nagoya Joint Symposium  2023.5.15 

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    Event date: 2023.5

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  9. 堅牢な多孔性分子導体の開発とゲスト分子による電子物性制御

    井口弘章

    2022年度量子ビームサイエンスフェスタ  2023.3.15 

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    Event date: 2023.3

    Language:English   Presentation type:Poster presentation  

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  10. 配位結合を用いた多孔性分子導体の開発 Invited

    井口弘章

    分子系の複合電子機能 第181委員会 最終研究会  2023.3.7 

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    Event date: 2023.3

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  11. Design of Electrically Conductive Nanowire Metal Complexes and Porous Molecular Conductors Invited International conference

    Hiroaki Iguchi

    Nankai Symposium on Advanced Functional Materials  2022.12.17 

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    Event date: 2022.12

    Language:English   Presentation type:Oral presentation (invited, special)  

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  12. 配位結合で構築する多孔性π積層骨格とその電子物性 Invited

    井口弘章

    第3回錯体化学会フロンティアセミナー 金属錯体で展開するナノ空間科学の最先端  2022.12.2 

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    Event date: 2022.12

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  13. 大環状金属錯体が稠密に積層した 多孔性分子導体の合成と物性

    井口弘章, Mengxing Cui, 村瀬龍一, Yongbing Shen, 佐藤鉄, 小山翔平, 内田海路, 田邉辰平, 高石慎也, 山下正廣

    第30回有機結晶シンポジウム  2022.11.5 

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    Event date: 2022.11

    Language:Japanese   Presentation type:Oral presentation (general)  

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  14. Crystal Structure and Conductive Properties of Porous Molecular Conductors Invited International conference

    Hiroaki Iguchi

    The 17th Conference of the Asian Crystallographic Association (AsCA2022)  2022.11.2 

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    Event date: 2022.10 - 2022.11

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  15. Porous Molecular Conductor Constructed from Densely Packed Hexagonal Metallocycle

    Hiroaki Iguchi, Mengxing Cui, Ryuichi Murase, Shinya Takaishi, MasahiroYamashita

    2022.9.27 

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    Event date: 2022.9

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  16. Electrically conductive metallocycle: densely packed molecular hexagons assembled by π-radicals Invited International conference

    Hiroaki Iguchi

    8th Asian Conference on Coordination Chemistry (ACCC8)  2020.8.9 

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    Event date: 2022.8

    Language:English   Presentation type:Oral presentation (invited, special)  

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  17. ナノサイズの孔を持つ分子性導体を創る

    井口弘章

    ITbM/GTRコンソーシアムワークショップ GTR Seeds Seminar  2022.6.29 

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    Event date: 2022.6

    Language:Japanese   Presentation type:Oral presentation (general)  

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  18. Syntheses and Physical Properties of Robust Porous Molecular Conductors with 1,2,4-Triazole Group

    Hiroaki Iguchi, Mengxing Cui, Yongbing Shen, Shohei Koyama, Shinya Takaishi

    2022.3.25 

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    Event date: 2022.3

    Presentation type:Oral presentation (general)  

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  19. 多孔性分子導体の開発:現況と問題点 Invited

    井口弘章

    2021年度物性研究所短期研究会・分子性固体研究の拡がり:新物質と新現象  2021.12.2 

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    Event date: 2021.12

    Presentation type:Oral presentation (invited, special)  

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  20. Porous Molecular Conductors Constructed from Linear Coordination Polymers with π-Radicals

    Hiroaki Iguchi, Liyuan Qu, Shohei Koyama, Shinya Takaishi, Masahiro Yamashita

    The 1st Asian Conference on Molecular Magnetism  2021.3.9 

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    Event date: 2021.3

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  21. 一次元電子系物質の電子状態制御:ナノワイヤー金属錯体から多孔性分子導体まで Invited

    井口弘章

    2020年度東北大学多元物質科学研究所高分子・ハイブリッド材料研究センター(PHyM)若手フォーラム  2020.10.20 

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    Event date: 2020.10

    Language:Japanese   Presentation type:Symposium, workshop panel (nominated)  

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  22. Porous Molecular Conductors: π-Radical-Based Self-Assembly for Constructing Electron-Conductive Coordination Networks Invited

    Hiroaki Iguchi

    2020.9.28 

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    Event date: 2020.9

    Language:English   Presentation type:Oral presentation (invited, special)  

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  23. Syntheses of Porous Molecular Conductors Triggerd by Reduction of Naphthalenediimide-Based Ligand

    井口弘章, 瞿李元, 小山翔平, 高石慎也, 山下正廣

    2020.5.29 

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    Event date: 2020.5

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  24. Development of Porous Molecular Conductors Constructed from Threefold Stack of Linear Coordination Polymers

    Hiroaki Iguchi, Liyuan Qu, Shohei Koyama, Shinya Takaishi, Masahiro Yamashita

    2020.3.24 

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    Event date: 2020.3

    Language:English   Presentation type:Oral presentation (general)  

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  25. Syntheses of Porous Molecular Conductors by Electrochemical Self-Assembly of Coordination Polymers

    29th Annual Meeting of MRS-J  2019.11.28 

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    Event date: 2019.11

    Language:Japanese   Presentation type:Oral presentation (general)  

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  26. Naphthalenediimide-based Porous Molecular Conductors Constructed from Linear Coordination Polymers Invited

    Hiroaki Iguchi

    The 13rd Japan-China Joint Symposium on Conduction and Photoconduction in Organic Solids and Related Phenomena  2019.10.22 

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    Event date: 2019.10

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  27. Porous Molecular Conductors Self-Assembled from Coordination Polymers with π-Radicals Invited

    Hiroaki Iguchi

    7th Asian Conference on Coordination Chemistry (ACCC7)  2019.10.17 

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    Event date: 2019.10

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  28. MX-type Single Chain Complexes with Aromatic In-plane Ligands

    Hiroaki Iguchi, Unjila Afrin, Shinya Takaishi, Masahiro Yamashita

    2019.9.22 

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    Event date: 2019.9

    Language:English   Presentation type:Oral presentation (general)  

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  29. Porous Molecular Conductors Self-Assembled from Coordination Polymers with π-Radicals Invited

    Hiroaki Iguchi

    5th Japan-Taiwan-Singapore-Hong Kong Quadrilateral Symposium on Coordination Chemistry (QSCC), Joint Symposium with Japan Society of Coordination Chemistry (JSCC) and Japan Society for Molecular Science (JSMS)  2019.9.21 

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    Event date: 2019.9

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  30. Porous Molecular Conductors: Conductive Soft Crystals Self-Assembled from Coordination Polymers with π-Radicals

    Hiroaki Iguchi, Liyuan Qu, Shohei Koyama, Shinya Takaishi, Masahiro Yamashita

    The 2nd International Symposium on Soft Crystals  2019.7.13 

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    Event date: 2019.7

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  31. ナフタレンジイミド系配位子と金属イオンを用いたポーラス分子性導体の合成

    有機固体若手の学校2017  2017.3.9 

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    Venue:湯河原  

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  32. 化学ドーピングの精密制御が可能な多孔性有機伝導体の創製

    IGUCHI Hiroaki

    東北大学学際科学フロンティア研究所平成29年度成果報告会  2018.2.28 

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  33. 低次元配位高分子のπ集積によるポーラス分子性導体の合成

    π造形科学 第3回公開シンポジウム  2016.10.20 

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    Venue:仙台  

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  34. 低次元配位高分子のπ集積によるポーラス分子性導体の合成

    東北大学学際科学フロンティア研究所平成28年度成果報告会  2017.2.15 

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    Venue:仙台  

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  35. 一次元電子系(金属)錯体の電子状態制御 Invited

    若手研究者のための機能性材料シンポジウム2016  2016.12.8 

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    Venue:山形  

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  36. 一次元電子系錯体の電子状態制御 Invited

    第9回ChemBioハイブリッドレクチャー  2016.10.8 

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    Venue:東京  

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  37. 一次元金属錯体の電子状態制御と多孔性分子導体の開発 Invited

    井口 弘章

    日本化学会中国四国支部 愛媛地区化学講演会  2018.12.3 

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  38. ヒドロキシ基を導入したMX 錯体における室温平均原子価相の実現

    第10回分子科学討論会  2016.9.13 

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    Venue:神戸  

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  39. ヒドロキシ基を導入した MX錯体における室温Pd(III)モット-ハバード相の実現

    物性研究所短期研究会 第1回固体化学フォーラム研究会:固体物質・材料研究の現在と未来  2016.6.14 

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    Presentation type:Poster presentation  

    Venue:柏  

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  40. ナフタレンジイミド誘導体を用いた導電性結晶の開発

    第33回無機・分析化学コロキウム  2016.6.3 

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    Venue:宮城県大崎市川渡  

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  41. Development of Highly Conductive Nanowire Metal Complexes and Porous Molecular Conductors Invited

    IGUCHI Hiroaki

    2018.11.8 

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  42. 臭素架橋Pd(III)ナノワイヤー金属錯体の開発と電子物性

    第26回日本MRS年次大会  2016.12.19 

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    Venue:横浜  

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  43. 擬一次元ハロゲン架橋金属錯体の電子状態制御

    「分子システム研究」第5回春季研究会  2016.5.13 

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    Venue:熱海  

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  44. 安定かつ高伝導なd電子系モット絶縁体:Pd(III)-Brナノワイヤー錯体の開発

    IGUCHI Hiroaki

    有機固体若手の会2018  2018.3.15 

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  45. 多孔性分子導体を基盤とした導電性ソフトクリスタルの創製

    IGUCHI Hiroaki

    ソフトクリスタル:高秩序で柔軟な応答系の学理と光機能 平成30年度第1回領域全体会議  2018.5.26 

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  46. Porous Molecular Conductors Constructed from Coordination Polymers with π-Radicals International conference

    IGUCHI Hiroaki

    6th International Conference on Metal-Organic Frameworks & Open Framework Compounds (MOF 2018)  2018.12.10 

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  47. MX及びMMX型擬一次元ハロゲン架橋金属錯体における電子状態制御

    第8回東北大学研究会プログラム~金属錯体と固体物性物理と生物物性の連携新領域を目指して~  2016.2.19 

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    Venue:仙台  

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  48. MMX型擬一次元ヨウ素架橋Pt錯体の固体電気化学

    錯体化学会第63回討論会  2013.11.2 

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    Venue:沖縄  

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  49. MMX-Chain-Based Flexible Framework: Changing The Electronic States and Conductivity by Dehydration and Electrochemical Oxidation International conference

    4th International Conference on Metal-Organic Frameworks & Open Framework Compounds (MOF2014)  2014.9.28 

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    Venue:JAPAN 神戸  

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  50. Highly Conductive and Thermally Stable Pd(III)-Br Chain Complex International conference

    IGUCHI Hiroaki

    43rd International Conference on Coordination Chemistry (ICCC2018)  2018.7.31 

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  51. Emergence of Conductivity by Chemical Reduction in Cu-Naphthalenediimide-Based Coordination Polymer International conference

    6th Asian Conference on Coordination Chemistry (ACCC6)  2017.7.23 

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    Venue:Australia メルボルン  

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  52. Controlling the electronic states and physical properties of semiconducting MX- and MMX-type chain complexes International conference

    The International Chemical Congress of Pacific Basin Societies 2015 (Pacifichem 2015)  2015.12.15 

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    Venue:ホノルル  

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  53. <SUP>129</SUP>IメスバウアースペクトルによるMMX型Chain錯体の電子状態の考察

    錯体化学会第64回討論会  2014.9.18 

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    Venue:東京  

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  54. ナフタレンジイミド型配位子を用いた多孔性分子導体の開発

    IGUCHI Hiroaki

    第12回分子科学討論会  2018.9.12 

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  55. ナノ細孔を有する分子性導体の開発

    2017年度「物質階層原理研究」第1回春期研究会  2017.5.12 

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    Venue:御殿場  

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  56. π-π相互作用と配位結合を利用した多孔性分子導体の創製

    IGUCHI Hiroaki

    日本化学会第98春季年会  2018.3.20 

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  57. Various Electronic Properties in One-Dimensional Electron Systems: Halogen-Bridged Metal Complexes, Naphthalenediimide-Based Conductor, and Ionic CT Liquid Crystal Invited International conference

    School of Chemistry Seminar Program, University of Sydney  2015.2.13 

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    Venue:Australia Sydney  

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  58. Syntheses of Porous Molecular Conductors Self-Assembled from Coordination Polymers with Naphthalenediimide-Radicals

    第66回高分子学会年次大会  2017.5.29 

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    Venue:千葉  

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  59. Solid State Electrochemistry of Semiconducting Diplatinum-Iodide Chain Complexes International conference

    The 4th Asian Conference on Coordination Chemistry (ACCC4)  2013.11 

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    Venue:Republic of Korea Jeju  

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  60. Porous Molecular Conductors: Self-Assembly of Coordination Polymers with Naphthalenediimide-Radicals

    錯体化学会第67回討論会  2017.9.18 

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    Venue:札幌  

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  61. Porous Molecular Conductors Synthesized by Using π-π Interaction and Coordination to Metal Ion International conference

    IGUCHI Hiroaki

    The 8th TOYOTA RIKEN International Workshop Organic Semiconductors, Conductors, and Electronics  2018.10.24 

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  62. Porous Molecular Conductors Self-Assembled from Coordination Polymers with π-Radicals

    日本化学会第97春季年会  2017.3.16 

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    Venue:横浜  

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  63. Porous Molecular Conductors Self-Assembled by Radical-Radical Interaction among Coordination Polymers International conference

    IGUCHI Hiroaki

    MOF2018 Young Investigator Symposium  2018.12.8 

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  64. Naphthalenediimide-Based Organic Conductors and Organic-Inorganic Hybrids International conference

    IGUCHI Hiroaki

    12th International Symposium on Crystalline Organic Metals, Superconductiors and Magnets (ISCOM2017)  2017.9.25 

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  65. Physical and Electrochemcal Properties of Semiconducting MMX-Type Chain Complexes International conference

    41st International Conference on Coordination Chemistry (ICCC-41)  2014.7.21 

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    Venue:Singapore Singapore  

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  66. One-Dimensional Organic-Inorganic Perovskite: Hybrid of PbBr5 Chain and Conductive Naphthalenediimide Column International conference

    42nd International Conference on Coordination Chemistry (ICCC-42)  2016.7.3 

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    Venue:ブレスト  

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KAKENHI (Grants-in-Aid for Scientific Research) 13

  1. Controlling Bulk Condensed Conjugation in Robust Metal-Organic Frameworks

    Grant number:23H04024  2023.4 - 2025.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Transformative Research Areas (A)

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    Authorship:Principal investigator 

    Grant amount:\7800000 ( Direct Cost: \6000000 、 Indirect Cost:\1800000 )

  2. Syntheses of Delta-pi Conjugated Metal Complexes toward Development of Porous Two-Dimensional Electron System

    Grant number:21K18971  2021.7 - 2023.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)  Grant-in-Aid for Challenging Research (Exploratory)

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    Authorship:Principal investigator 

    Grant amount:\6370000 ( Direct Cost: \4900000 、 Indirect Cost:\1470000 )

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  3. Organic nanocrystalline heterostructures for high energy density electrode materials

    Grant number:21H04696  2021.4 - 2026.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)  Grant-in-Aid for Scientific Research (A)

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  4. Syntheses of Porous Molecular Conductors toward Creating and Controlling Novel Electronic States

    Grant number:21H01901  2021.4 - 2024.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

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    Grant amount:\17810000 ( Direct Cost: \13700000 、 Indirect Cost:\4110000 )

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  5. Innovative Functions Originating from Unexploited Electronic States in Nanowire Metal Complexes

    Grant number:19H05631  2019.6 - 2024.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)  Grant-in-Aid for Scientific Research (S)

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  6. Continuous carrier control of redox MOFs by electrochemical doping

    Grant number:19H02729  2019.4 - 2023.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

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  7. 分子磁性体内包単層カーボンナノチューブによる新奇磁気特性の発現と向上

    Grant number:19H00898  2019.4 - 2020.3

    日本学術振興会  科学研究費助成事業 基盤研究(A)  基盤研究(A)

    山下 正廣, 高石 慎也, 加藤 恵一, 井口 弘章, 高石 慎也, 加藤 恵一, 井口 弘章

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    本研究では、分子磁性体の構造を一次元的に制御し、かつ電子の流れるパスとして機能する分子材料として単層のカーボンナノチューブ(CNT)に注目した。単層CNTは直径数nm、長さ数μmと非常に大きなアスペクト比を持つ量子細線である。本研究では単層CNTの特徴である一次元内部空間を利用し、ここに分子磁性体を内包することで分子性磁性内包単層CNTを創製した。内包に用いた希土類内包フラーレン分子であるDySc2N@C80はDyイオンの大きな磁気異方性に由来する単分子磁石特性を示す。さらに、DySc2N@C80を単層CNTに内包することでDySc2N@C80が一次元的に整列し、単分子磁石間に働く磁気双極子相互作用が基底状態に作用し保持力の向上が確認された。また、一次元的に磁気希釈されているために分子間磁気相互作用が働かない。この一次元内包単分子磁石の分子スピントロニクス材料としての機能に注目した。電極間に一次元内包単分子磁石をセットし電流磁気特性を調べたところ、金電極では磁気抵抗効果は観測されなかった。一方、ニッケル電極では0.4%程度ではあるが磁気抵抗効果が観測された。今後は再現性も含め他の金属電極での挙動について研究を進める。また、局在スピンと伝導電子の相互作用についても詳細に検討していく予定である。

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  8. Functional one-dimensional metal complexes developed by controlling their electronic states

    Grant number:18K14233  2018.4 - 2021.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Early-Career Scientists  Grant-in-Aid for Early-Career Scientists

    Iguchi Hiroaki

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    Grant amount:\4160000 ( Direct Cost: \3200000 、 Indirect Cost:\960000 )

    I have explored new electronic states of quasi-one-dimensional halogen-bridged metal complexes (so-called MX chains) by modifying organic in-plane ligands. Introduction of multiple hydrogen bonds among ligands and counteranions gave the Pt-Cl and Pt-Br chains with the smallest optical gaps. Moreover, the first zigzag-type Pd-Br chain with unusual Pd(III) oxidation state was synthesized. It showed high electrical conductivity up to 0.05 S/cm.
    In contrast to the above strategy that shrinks M-X-M distances, I succeeded to obtain the Pt-Br chain with the longest M-X-M distance by using the pi-staking interaction between in-plane ligands. Remarkably, this complex showed negligible intermetallic interaction, suggesting that the complex falls into Robin-Day class I state for the first time in MX chains.

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  9. Conductive Soft Crystals Based on Porous Molecular Conductor

    Grant number:18H04498  2018.4 - 2020.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)  Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

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    Authorship:Principal investigator 

    Grant amount:\4940000 ( Direct Cost: \3800000 、 Indirect Cost:\1140000 )

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  10. Syntheses of molecule-responsive porous materials based on one-dimensional electron system

    Grant number:15K17828  2015.4 - 2017.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)  Grant-in-Aid for Young Scientists (B)

    Iguchi Hiroaki

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    Authorship:Principal investigator 

    Grant amount:\4160000 ( Direct Cost: \3200000 、 Indirect Cost:\960000 )

    In this research, I have studied (1) quasi-one-dimensional halogen-bridged metal complexes (MX chains) and (2) metal-organic frameforks (MOF) with pi-stacked column to develop the porous materials which can change their properties by molecular desoption and adsorption.
    In (1), the new PdBr chain, which shows the top record of the conductivity in MX chains (3-38 Scm-1) and highest stability (Pd(III) state stable up to 443 K), was synthesized. The great functions of the PdBr chain can be originated from the multiple hydrogen-bond networks in the crystal.
    In (2), I found that both chemical reduction and electrochemical reduction method are useful to achieve the introduction of conductive pi-stacked column into the MOF.

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  11. Creation of novel nonlinear properties in nanowire metal complexes with strong electron correlation

    Grant number:26248015  2014.4 - 2018.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)  Grant-in-Aid for Scientific Research (A)

    Yamashita Masahiro

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    We have succeeded in synthesizing the novel Pd-Br chain compound with averaged valence state which is stable up to 400 K. We measured physical properties of this compound. This compound showed extremely high electrical conductivity (40 Scm-1at room temperature), which is 10^6 higher than previous Pd-Br compound. The averaged valence state was stable up to 443 K(decomposition temperature). Such a stable averaged valence state has not been shown in the previous Pd-Br chains. This is because hydrogen bond between hydroxy group of the dabdOH ligand and Br- ion made 1D chains far away each other, and resultantly compression of 1D chain direction occured.
    We also measured thermoelectoric property of a series of MX chain compounds. We measured [Ni1-xCox(chxn)2Br]Br2. The pure [Ni(chxn)2Br]Br2 showed negative Seebeck efficient, whereas the absolute value of that decreased with increasing Co ratio.

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  12. 分子の自己組織化を駆使した低次元電子系物質の特異機能発現

    Grant number:11J01608  2011 - 2013

    日本学術振興会  科学研究費助成事業 特別研究員奨励費  特別研究員奨励費

    井口 弘章, 井口 弘章

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    昨年度までの研究で、強いドナー分子として直鎖アルキル基を導入したジヒドロフェナジン(DHP)誘導体を合成し、強いアクセプターであるテトラシアノキノジメタン(TCNQ)と複合化させることで、電荷移動(CT)錯体を得ることができたが、その固体は微結晶体であり、液晶のようなソフトマテリアルではなかった。また、アルキル鎖によって固体のバンドギャップが変化する原因も不明であった。そこで本年度は、CT錯体にさらなる柔軟性を付加するため、分岐型アルキル鎖を導入したDHP誘導体を合成した。
    TCNQと複合化させたCT錯体は、偏光顕微鏡下で複屈折を示し、x線回折測定からカラムナーレクタンギュラー相の液晶であり、ドナー分子とアクセプター分子が交互積層していることが明らかとなった。
    赤外吸収スペクトルは、このCT錯体が電荷分離したイオン性にあることを示しており、この物質が世界初のイオン性交互積層型CT錯体からなるカラムナー液晶であることが明らかとなった。この液晶はラビング処理によってラメラ相と考えられる中間相に変化するが、このときラビング方向に対してドナー分子の長軸が配向し、一般的な円盤状カラムナー液晶とは逆の吸収異方性が現れた。これはドナー分子を単純な円盤ではなく、楕円形に近似可能な分子設計を行ったためであり、むしろ棒状液晶に近い性質を発現させることができたといえる。
    これら今年度と昨年度に合成したCT錯体の溶液中における会合定数を算出したところ、会合定数の増加とバンドギャップエネルギーとの間に明確な正の相関があることが明らかとなった。この原因は、会合定数が大きいほど固体中におけるドナー・アクセプター間距離が縮まっていることに由来すると考えられる。これは、溶液中の物性(会合定数)と固体における物性(バンドギャップエネルギー)の間にある関係を明らかにした初めての例といえる。

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  13. 表面・界面を利用した低次元有機・無機複合物質の革新的機能の創出

    Grant number:09J05491  2009 - 2010

    日本学術振興会  科学研究費助成事業 特別研究員奨励費  特別研究員奨励費

    井口 弘章, 井口 弘章

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    1.MMX錯体の固体電気化学測定による酸化還元挙動の解明
    当研究者らは、MMX型擬一次元ハロゲン架橋金属錯体(MMX錯体)の中でも、pop(=P_2O_5H_2^<2->)配位子と2種類の対カチオンを有する錯体K_2(H_3NC_3H_6NH_3)[Pt_2(pop)_4I]・4H_2O(1・4H_2O)が、可逆的に水分子を吸脱着し、その物性が変化することを以前に報告した。この吸脱着能は、結晶内の一次元空孔における壁(鎖状分子)と水分子との間に化学的な相互作用があることに由来しており、この一次元空孔内の界面における相互作用を他の分子やイオンへと適応する可能性を探索するため、MMX錯体として初めて固体電気化学測定を行った。この錯体の還元反応は化学的に非可逆であり、電解質のサイズが大きくなるほど還元電位が低くなり、挿入が起こりにくいことを明らかにした。一方、錯体の酸化反応は化学的にはほぼ可逆であり、対カチオンが酸化に伴って脱離し、再還元の際には溶液中の電解質が空いたサイトに取り込まれることを示した。この電解質がテトラブチルアンモニウムイオンのように嵩高い場合には、再還元が起こらないことを明らかにした。脱水状態(1)では溶液への溶解性が増大してしまうために、可逆的な酸化還元挙動を得ることはできなかったが、このような固体中における電気化学的手法が、導電性の錯体の機能化に有用である可能性を示すことができた。
    2.MMX錯体の^<129>Iメスバウアースペクトルの測定による電子状態変化の解明
    上記含水錯体1・4H_2O及び脱水錯体1の電子状態を^<129>Iメスバウアースペクトルの測定によって明らかにした。脱水によってヨウ化物イオンは2種類から1種類へと変化したことから、脱水による構造及び電子状態の変化は、結晶全体に渡って起こっていることが明らかとなった。

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