Directory of Researchers
| TAKAHASHI Kazuyuki |  |
| Graduate School of Science / Division of Chemistry | |
| Associate Professor | |
| Chemistry |
Researcher Profile and Settings
Affiliation
＜Faculty / Graduate School / Others＞
Graduate School of Science / Division of Chemistry＜Related Faculty / Graduate School / Others＞
Faculty of Science / Department of Chemistry
Teaching
- Graduate School of Science / Division of Chemistry, 2019, Inorganic Chemistry I
- Graduate School of Science / Division of Chemistry, 2019, Inorganic Chemistry I
- Faculty of Science / Department of Chemistry, 2019, First Year Seminar
- Faculty of Science / Department of Chemistry, 2019, Survey of Chemistry
- Faculty of Science / Department of Chemistry, 2019, Advanced Inorganic Chemistry 1
- Faculty of Science / Department of Chemistry, 2019, Inorganic Chemistry Ⅲ
- Faculty of Science / Department of Chemistry, 2019, Inorganic Chemistry III-1
- Faculty of Science / Department of Chemistry, 2019, Inorganic Chemistry III-2
- Faculty of Science / Department of Chemistry, 2019, Introduction to Inorganic Chemistry
- Faculty of Science / Department of Chemistry, 2019, Introduction to Inorganic Chemistry 1
- Faculty of Science / Department of Chemistry, 2019, Exercise on Inorganic and Analytical Chemistry
- Office for the Promotion of International Exchange, 2019, Chemistry Laboratory 1
- Office for the Promotion of International Exchange, 2019, Chemistry Laboratory 2
Research Activities
Research Interests
Research Areas
- Nanotechnology/Materials / Functional solid-state chemistry
- Nanotechnology/Materials / Inorganic and coordination chemistry
- Nanotechnology/Materials / Structural/physical organic chemistry
Awards
Oct. 2019 Graduate School of Science, Kobe University, Poster Presentation Award, アニオンのサイズ形状による鉄(II)スピンクロスオーバー錯体の磁気挙動の変化
Dec. 2018 神戸大学 研究基盤センター, 神戸大学 研究基盤センター 若手フロンティア研究会 ポスター賞「極低温部門賞」, 配位能を持つアクセプターからなる錯体の構造と性質
Japan society
Dec. 2014 神戸大学研究基盤センター, 優秀賞（神戸大学研究基盤センター若手フロンティア研究会2014）, 磁性アニオンを含有した鉄(II)錯体の構造と磁気物性
Japan society
Sep. 2014 分子科学会, 優秀ポスター賞（第8回分子科学討論会2014 ）, プロトンドナー性配位子を用いた鉄(II)錯体の構造と物性
Japan society
Published Papers
© 2020 American Physical Society. We explore the electrical and magnetic properties of a fractal assembly of Josephson junctions with transparent interfaces. For this purpose, we employ an Mg/MgO/MgB2 nanocomposite with ∼16 vol. % of MgB2 nanograins, which are distributed in a fractal manner in the normal matrix. Irrespective of the low volume fraction of MgB2 nanograins, the nanocomposite behaves as a bulk-like superconductor, i.e., zero resistivity, perfect diamagnetism, and strong vortex pinning. Thus, a global Josephson phase coherence is achieved in the nanocomposite. The lower (Hc1J) and higher (Hc2J) critical fields of the Josephson network are exceptionally high (Hc1J=96Oe and Hc2J=83.5kOe) as compared to those reported previously for granular superconductors. This will give an example of robust macroscopic superconducting coherence derived from long-range proximity coupling among fractally distributed superconducting nanograins through quantum interference of Andreev quasiparticles. Transverse-field muon spin rotation measurements reveal that the mean internal field in the superconducting mixed state increases with decreasing temperature below which the Josephson phase coherence sets in, opposite to the diamagnetic response observed in magnetization measurements. This unusual behavior implies a highly disordered and fluctuating nature of the Josephson vortices in the present superconducting nanocomposite.
Jan. 2020, Physical Review B, 101 (3), 035146, English, International magazine[Refereed]
Scientific journal
- Jun. 2019, Dalton Trans., 48 (23), 8053 - 8056, English
[Refereed]
Scientific journal
- Feb. 2019, Crystals, 9 (2), 81 (22 pages), English
[Refereed][Invited]
Scientific journal
- Feb. 2019, J. Phys. Chem. C, 123 (11), 6599–6606, English
[Refereed]
Scientific journal
- Nov. 2018, Journal of Molecular Liquids, 269 ((2018)), 882–885, English
[Refereed]
Scientific journal
- Jul. 2018, Chem. Eur. J., 24, 9490 - 9493, EnglishPhotogeneration of Microporous Amorphous Coordination Polymers from Organometallic Ionic Liquids
[Refereed]
Scientific journal
In recent years, ionic plastic crystals have attracted much attention. Many metallocenium salts exhibit plastic phases, but factors affecting their phase transitions are yet to be elucidated. To investigate these factors, we synthesized octamethylferrocenium salts with various counteranions [Fe(C5Me4H)2]X ([1]X X- = B(CN)4 -, C(CN)3 -, N(CN)2 -, FSA (= (SO2F)2N-), FeCl4 -, GaCl4 - and CPFSA (= CF2(SO2CF2)2N-)) and elucidated their crystal structures and phase behavior. Correlations between the crystal structures and phase sequences, and the shapes and volumes of the anions are discussed. Except for [1][CPFSA], these salts exhibit phase transitions to plastic phases at or above room temperature (TC = 298-386 K), and the plastic phases exhibit either NaCl- or anti-NiAs-type structures. X-ray crystal structure analyses of these salts at 100 K revealed that they have structures in which cations and anions are alternately arranged, with the exception of [1][CPFSA]. [1][CPFSA] exhibits a structure in which anions and cations are separately stacked to form columns. [1][N(CN)2] exhibits a polar crystal structure that undergoes a monotropic phase transition to a centrosymmetric structure. The magnetic susceptibilities of room-temperature plastic crystals [1][GaCl4] and [1][FeCl4] were investigated the latter exhibits a small ferromagnetic interaction at low temperatures.
Royal Society of Chemistry, Feb. 2018, Phys. Chem. Chem. Phys., 20 (5), 3019 - 3028, English[Refereed]
Scientific journal
A series of [FeII(L)2](BF4)2 compounds were structurally and physically characterized (L = 2,6-bis(2-methylthiazol-4-yl)pyridine). A crystal structure phase transformation from dihydrate compound 1 to anhydrous compound 3 through partially hydrated compounds 2 and 2′ upon dehydration was found. Compounds 1 and 3 exhibited a gradual spin crossover (SCO) conversion, whereas compounds 2 and 2′ demonstrated two-step and one-step abrupt SCO transitions, respectively. An X-ray single-crystal structural analysis revealed that one-dimensional and two-dimensional Fe cation networks linked by π stacking and sulfur-sulfur interactions were formed in 1 and 3, respectively. A thermodynamic analysis of the magnetic susceptibility for 1, 2′, and 3 suggests that the enthalpy differences may govern SCO transition behaviors in the polymorphic compounds 2′ and 3. A structural comparison between 1 and 3 indicates that the SCO behavior variations and crystal structure transformation in the present [FeII(L)2](BF4)2 compounds can be interpreted by the relationship between the lattice enthalpies mainly arising from Coulomb interactions between the Fe cations and BF4 anions as in typical ionic crystals.
American Chemical Society, Feb. 2018, Inorg. Chem., 57 (3), 1277 - 1287, English[Refereed]
Scientific journal
To develop a new spin-crossover functional material, a magnetic hybrid compound [Fe(qsal)2][Ni(mnt)2] was designed and synthesized (Hqsal = N-(8-quinolyl)salicylaldimine, mnt = maleonitriledithiolate). The temperature dependence of magnetic susceptibility suggested the coexistence of the high-spin (HS) Fe(III) cation and π-radical anion at room temperature and a magnetic transition below 100 K. The thermal variation of crystal structures revealed that strong π-stacking interaction between the π-ligand in the [Fe(qsal)2] cation and [Ni(mnt)2] anion induced the distortion of an Fe(III) coordination structure and the suppression of a dimerization of the [Ni(mnt)2] anion. Transfer integral calculations indicated that the magnetic transition below 100 K originated from a spin-singlet formation transformation in the [Ni(mnt)2] dimer. The magnetic relaxation of Mössbauer spectra and large thermal variation of a g-value in electron paramagnetic resonance spectra below the magnetic transition temperature implied the existence of a magnetic correlation between d-spin and π-spin.
MDPI Multidisciplinary Digital Publishing Institute, Aug. 2017, Inorganics, 5 (3), 54 (14 pages), English[Refereed]
Scientific journal
A novel neutral heteroleptic Fe-III complex from two kinds of pi-extended tridentate ligands was designed and prepared. The pi-ligands formed a three-dimensional purely pi-stacking interaction network. The present complex proved to be the first neutral spincrossover (SCO) Fe-III complex with a N3O3 coordination sphere exhibiting an abrupt SCO transition with a thermal hysteresis of 10 K and the light-induced excited spin-state trapping effect.
Corresponding, ROYAL SOC CHEMISTRY, May 2017, Dalton Trans., 46 (18), 5786 - 5789, English[Refereed]
Scientific journal
Novel pseudopolymorphic Hdabco compounds with an Fe(III) complex anion, (Hdabco)[Fe(aznp)2]·CH2Cl2 1 and (Hdabco)[Fe(aznp)2]·0.5H2O 2 [dabco = 1,4-diazabicyclo[2.2.2]octane, H2aznp = (2′-hydroxyphenylazo)-2-hydroxynaphthalene], were prepared and characterized. The magnetic susceptibility for 1 and 2 revealed that both complexes were in a high-spin (HS) state in the whole temperature range and exhibited weak ferromagnetic interactions below 40 K. The crystal structural analyses suggested that strong N–H⋯O hydrogen bonding interactions between the Hdabco cation and [Fe(aznp)2] anion may induce the distortion of a coordination structure resulting in the HS complexes, whereas π-stacking interactions between the π-ligands in the [Fe(aznp)2] anion and additional C–H⋯N hydrogen bonding interactions between the Hdabco cation and [Fe(aznp)2] anion constructed a intermolecular interaction framework structure with one-dimensional channels. The thermogravimetry analysis for compound 1 indicated the adsorption of a water molecule took place after the desorption of a dichloromethane molecule. This transformation of 1 into 2 proved to proceed in a single-crystal-to-single-crystal way by powder X-ray diffractions and single crystal X-ray structural analysis.
Corresponding, Elsevier Ltd, 2017, Polyhedron, 136, 170 - 175, English[Refereed]
Scientific journal
Among the various thermochromic materials, liquid thermochromic materials are comparatively rare. To produce functional thermochromic liquids, we have designed ionic liquids based on cationic nickel complexes with ether side chains, [Ni(acac)((Me2NC2H4NRR2)-R-1)]Tf2N ([1]Tf2N: R-1 = C3H6OEt, R-2 = Me; [2]Tf2N: R-1 = C3H6OMe, R-2 = Me; [3]Tf2N: R-1 = R-2 = C3H6OMe), where acac = acetylacetonate and Tf2N=(F3CSO2)(2)N-. The side chains (R-1, R-2) can moderately coordinate to the metal center, enabling temperature-dependent coordination equilibria in the liquid state. [1]Tf2N is a liquid at room temperature. [2]Tf2N is obtained as a solid (T-m=352.7 K) but remains liquid at room temperature after melting. [3]Tf2N is a solid with a high melting point (T-m=422.3 K). These salts display thermochromism in the liquid state, appearing red at high temperatures and orange, light-blue, or bluish-green at lower temperatures, and exhibiting concomitant changes in their magnetic properties. This phenomenon is based on temperature-dependent equilibrium between a square-planar diamagnetic species and a paramagnetic species with intramolecular ether coordination.
WILEY-V C H VERLAG GMBH, Jan. 2017, Chemistry - A European Journal, 23 (4), 823–831 - 831, English[Refereed]
Scientific journal
The polarization switching mechanism is used in various devices such as pyroelectric sensors and memory devices. The change in polarization mostly occurs by ion displacement. The development of materials whose polarization switches via electron transfer in order to enhance operation speed is a challenge. We devised a synthetic and crystal engineering strategy that enables the selective synthesis of a [CrCo] heterometallic dinuclear complex with a polar crystal structure, wherein polarization changes stem from intramolecular charge transfer between co and the ligand. Polarization can be modulated both by visible-light irradiation and temperature change. The introduction of chiral ligands was paramount to the successful polarization switching in the valence tautomeric compound. Mixing Cr and Co complexes with enantiopure chiral ligands resulted in the selective formation of only pseudosymmetric [CrCo] heterometallic complexes. Furthermore, the left-handed chiral ligands preferentially interacted with their right-handed counterparts, enabling molecules to form a polar crystal structure.
AMER CHEMICAL SOC, Oct. 2016, J. Am. Chem. Soc., 138 (43), 14170 - 14173, English[Refereed]
Scientific journal
A pure organic single crystal, [H(2)dabco]center dot[2CB](2) ([H(2)dabco](2+) = diprotonated 1,4-diazabicyclo[2.2.2]octane, 2CB(-) = 2-chlorobenzoate), which undergoes a ferroelectric-to-paraelectric phase transition above room temperature (similar to 323 K upon heating), was prepared and characterized. This ferroelectric crystal possesses a distinctive supramolecular architecture composed of discrete H-bonded trimeric units (two 2CB(-) anions bridged by one [H(2)dabco](2+) cation through N-H center dot center dot center dot O hydrogen bond interactions). In the paraelectric phase, the [H(2)dabco](2+) cation is rotationally disordered and lies at the symmetric center of the trimer. Upon cooling, it is frozen in an ordered state and deviates toward a 2CB(-) anion at one end along the H-bond. The collective displacement of the cations leads to a polarization of the single crystal along the crystallographic c axis, which is confirmed by the temperature dependence of the second harmonic generation and spontaneous polarization. A significant increase in the phase transition temperature of the deuterated analogue suggests that the proton plays an important role in the ferroelectric phase transition.
AMER CHEMICAL SOC, Aug. 2016, J. Am. Chem. Soc., 138 (37), 12005 - 12008, English[Refereed]
Scientific journal
Many efforts are under way to control the structure of heterointerfaces in nanostructured composite materials for designing functionality and engineering application. However, the fabrication of high-quality heterointerfaces is challenging because the crystal/crystal interface is usually the most defective part of the nanocomposite materials. In this work, we show that fully dense insulator (MgO)/semiconductor(Mg2Si)/superconductor (MgB2) nanocomposites with atomically smooth and continuous interfaces, including epitaxial-like MgO/Mg2Si interfaces, are obtained by solid phase reaction between metallic magnesium and a borosilicate glass. The resulting nanocomposites exhibit a semiconductor-superconducting transition at 36K owing to the MgB2 nanograins surrounded by the MgO/Mg2Si matrix. This transition is followed by the intergrain phase-lock transition at similar to 24K due to the construction of Josephson-coupled network, eventually leading to a near-zero resistance state at 17 K. The method not only provides a simple process to fabricate dense nanocomposites with high-quality interfaces, but also enables to investigate the electric and magnetic properties of embedded superconducting nanograins with good intergrain coupling. Published by AIP Publishing.
AMER INST PHYSICS, Jul. 2016, J. Appl. Phys., 120 (1), 10, English[Refereed]
Scientific journal
To investigate the pi-extension effect on an unusual negative-charged spin crossover (SCO) FeIII complex with a weak N2O4 first coordination sphere, we designed and synthesized a series of anionic FeIII complexes from a pi-extended naphthalene derivative ligand. Acetonitrile-solvate tetramethylammonium (TMA) salt 1 exhibited an SCO conversion, while acetone-solvate TMA salt 2 was in a high-spin state. The crystal structural analysis for 2 revealed that two-leg ladder-like cation-anion arrays derived from pi-stacking interactions between pi-ligands of the FeIII complex anion and Coulomb interactions were found and the solvated acetone molecules were in one-dimensional channels between the cation-anion arrays. A desolvation-induced single-crystal-to-single-crystal transformation to desolvate compound 2' may be driven by Coulomb energy gain. Furthermore, the structural comparison between quasi-polymorphic compounds 1 and 2 revealed that the synergy between Coulomb and pi-stacking interactions induces a significant distortion of coordination structure of 2.
Corresponding, MDPI AG, May 2016, Crystals, 6 (5), 49 (16 pages), English[Refereed][Invited]
Scientific journal
Unprecedented anionic Fe-III spin crossover (SCO) complexes involving a weak-field O,N,O-tridentate ligand were discovered. The SCO transition was evidenced by the temperature variations in magnetic susceptibility, Mossbauer spectrum, and coordination structure. The DFT calculations suggested that larger coefficients on the azo group in the HOMO-1 of a ligand might contribute to the enhancement of a ligand-field splitting energy. The present anionic SCO complex also exhibited the light-induced excited-spin-state trapping effect.
WILEY-V C H VERLAG GMBH, Jan. 2016, Chem. Eur. J., 22 (4), 1257 - 1257, English[Refereed]
Scientific journal
Salts comprising of cationic half-sandwich Ru(II) complexes with various chelating ligands and the bis (trifluoromethanesulfonyl) amide anion (Tf2N-) were prepared. These salts can be represented as [(arene) RuCl(L-L)][Tf2N] (arene = C6Me5Bu, C6Me6, p-cymene, C6H6; L-L = 2-Py-CH2NHCMe2Et, 2-Py-CH= NC6H13, H13C6NHCH2CH2NHC6H13, Me2NCH2CH2SC4H9, Me2CN=CHCH=NCMe2). Two of the eight salts are liquids at room temperature (similar to 20 degrees C), while the other salts are solids with melting points of 60-130 degrees C. Upon cooling from the melt, most salts exhibited glass transitions between -30 degrees C and -5 degrees C. The salts were found to catalyze the oxidation of cyclohexanol although decomposition occurred during the reaction. Crystal structures of related salts were also determined. (C) 2015 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE SA, Nov. 2015, Inorganica Chimica Acta, 438, 112 - 117, English[Refereed]
Scientific journal
Chiral molecular crystals built up by chiral molecules without inversion centers have attracted much interest owing to their versatile functionalities related to optical, magnetic, and electrical properties. However, there is a difficulty in chiral crystal growth due to the lack of symmetry. Therefore, we made the molecular design to introduce intermolecular hydrogen bonds in chiral crystals. Racemic and enantiopure bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) derivatives possessing hydroxymethyl groups as the source of hydrogen bonds were designed. The novel racemic trans-vic-(hydroxymethyl)(methyl)-BEDT-TTF 1, and racemic and enantiopure trans-vic-bis(hydroxymethyl)-BEDT-TTF 2 were synthesized. Moreover, the preparations, crystal structure analyses, and electrical resistivity measurements of the novel achiral charge transfer salt theta(21)-[(S,S)-2](3)[(R,R)-2](3)(ClO4)(2) and the chiral salt alpha'-[(R,R)-2]ClO4(H2O) were carried out. In the former theta(21)-[(S,S)-2](3)[(R,R)-2](3)(ClO4)(2), there are two sets of three crystallographically independent donor molecules [(S,S)-2](2)[(R,R)-2] in a unit cell, where the two sets are related by an inversion center. The latter alpha'-[(R,R)-2]ClO4(H2O) is the chiral salt with included solvent H2O, which is not isostructural with the reported chiral salt alpha'-[(S,S)-2]ClO4 without H2O, but has a similar donor arrangement. According to the molecular design by introduction of hydroxy groups and a ClO4- anion, many intermediate-strength intermolecular hydrogen bonds (2.6-3.0 angstrom) were observed in these crystals between electron donor molecules, anions, and included H2O solvent, which improve the crystallinity and facilitate the extraction of physical properties. Both salts are semiconductors with relatively low resistivities at room temperature and activation energies of 1.2 ohm cm with E-a = 86 meV for theta(21)-[(S,S)-2](3)[(R,R)-2](3)(ClO4)(2) and 0.6 ohm cm with E-a = 140 meV for alpha'-[(R,R)-2](2)ClO4(H2O), respectively. The variety of donor arrangements, theta(21) and two kinds of alpha'-types, and their electrical conductivities of charge transfer complexes based upon the racemic and enantiopure (S,S)-2, and (R,R)-2 donors originates not only from the chirality, but also the introduced intermolecular hydrogen bonds involving the hydroxymethyl groups, perchlorate anion, and the included solvent H2O.
BEILSTEIN-INSTITUT, Sep. 2015, Beilstein J. Org. Chem., 11 (Sept), 1561 - 1569, English[Refereed]
Scientific journal
To introduce both an inter-sulphur atom and p-stacking interaction between a spin crossover (SCO) cation and paramagnetic anion, we designed and synthesised two novel Fe(II) SCO compounds involving a terpyridine-type thiazole containing ligand with the paramagnetic Ni(dmit)(2) and nonmagnetic Au(dmit)(2) anion (dmit = 4,5-dithiolato-1,3-dithiole-2-thione). The temperature variations of magnetic susceptibility and Mossbauer spectroscopy revealed that both complexes exhibited an almost complete SCO conversion, and moreover, the Ni(dmit)(2) anion was in a paramagnetic state down to 2 K. The crystal structures for the Ni(dmit)(2) complex at 213 and 400 K indicated that the chalcogen-bond and p-stacking interaction would be enhanced by the electrostatic interaction between the cation and anion, preventing the p-radicals from dimerising. The light-induced excited spin state trapping effect was observed at 5 K.
Corresponding, ROYAL SOC CHEMISTRY, Aug. 2015, J. Mater. Chem. C, 3 (30), 7858 - 7864, English[Refereed][Invited]
Scientific journal
- Jul. 2015, Beilstein J. Org. Chem., 11 (July), 1147, English
[Refereed]
Scientific journal
A novel star-shaped high-spin Fe(III) tetranuclear cluster was unexpectedly obtained by the reaction of an [Fe-III(phsal)(2)](-) anion with an Fe(III) coordination cation (H(2)phsal: N-(2-hydroxyphenyl)salicylaldimine). Despite a star-shaped Fe(III) tetranuclear structure similar to reported Fe(III) single molecule magnets, the present compound exhibited a bulk antiferromagnetic transition at 0.6 K due to a magnetic exchange coupling through intercluster pi-stacking interactions.
CHEMICAL SOC JAPAN, Mar. 2015, Chem. Lett., 44 (6), 840 - 842, English[Refereed]
Scientific journal
[Dineopentyl-biferrocene](2)[CI(1)TCNQ](7), which has an unprecedented high donor-acceptor ratio of 2:7, contains a linear paramagnetic hexamer of Cl(1)TCNQ. Both the donor and acceptor molecules exhibit charge disproportionation in the crystal through mutual electrostatic interactions.
ROYAL SOC CHEMISTRY, Nov. 2014, Chemical Communications, 50 (87), 13372 - 13372, English[Refereed]
Scientific journal
Many molecular machines with controllable molecular-scale motors have been developed. However, transmitting molecular movement to the macroscopic scale remains a formidable challenge. Here we report a single crystal of a Ni complex whose shape changes abruptly and reversibly in response to thermal changes at around room temperature. Variable-temperature single-crystal X-ray diffraction studies show that the crystalline shape change is induced by an unusual 90 degrees rotation of uniaxially aligned oxalate molecules. The oxalate dianions behave as molecular-scale rotors, with their movement propagated through the entire crystalline material via intermolecular hydrogen bonding. Consequently, the subnanometrescale changes in the oxalate molecules are instantly amplified to a micrometre-scale contraction or expansion of the crystal, accompanied by a thermal hysteresis loop. The shape change in the crystal was clearly detected under an optical microscope. The large directional deformation and prompt response suggest a role for this material in microscale or nanoscale thermal actuators.
NATURE PUBLISHING GROUP, Oct. 2014, Nat. Chem., 6 (12), 1079 - 1083, English[Refereed]
Scientific journal
We report the results of SQUID and torque magnetometry of an organic spin-1/2 triangular-lattice kappa - H(3)dCat-EDT-TTF)(2). Despite antiferromagnetic exchange coupling at 80-100 K, we observed no sign of antiferromagnetic order down to 50 mK owing to spin frustration on the triangular lattice. In addition, we found nearly temperature-independent susceptibility below 3 K associated with Pauli paramagnetism. These observations suggest the development of gapless quantum spin liquid as the ground state. On the basis of a comparative discussion, we point out that the gapless quantum spin liquid states in organic systems share a possible mechanism, namely the formation of a band with a Fermi surface possibly attributed to spinons.
17, May 2014, Physical review letters, 112 (17), 1 - 177201, English[Refereed]
Scientific journal
To introduce halogen-bond interactions between a cation and an anion, a novel Fe-III complex from iodine-substituted ligands involving a paramagnetic nickel dithiolene anion was prepared and characterized. The compound exhibited the synergy between a spin-crossover transition and a spin-Peierls-like singlet formation. The halogen-bond interactions between the iodine and the sulfur atoms stabilized the paramagnetic state of -spins and played a crucial role in the synergistic magnetic transition between d- and -spins. In addition, the compound showed the light-induced excited spin state trapping effect.
Corresponding, WILEY-V C H VERLAG GMBH, Feb. 2014, Angew. Chem. Int. Ed., 53 (7), 1983 - 1986, English[Refereed]
Scientific journal
Polycrystalline powders of Cu(TCNQ) (TCNQ = 7,7',8,8'-tetracyanoquinodimethane) absorb iodine to form Cu(TCNQ)I-4 upon solid grinding with iodine or immersion in a hexane solution of iodine. Of the two polymorphs of Cu(TCNQ), phase II Cu(TCNQ) exhibits a much slower iodine-absorption rate than that of phase I Cu(TCNQ) in the liquid-phase reaction, whereas the solid grinding reaction results in efficient absorption for both phases. The valence state of the iodine-containing salt is [Cu+I-(TCNQ(0))](I-2)(1.5), where the copper ion is coordinated with an iodide anion and neutral TCNQ. The salt is a semiconductor (sigma(RT) = 3 x 10(-3) S cm(-1), compaction pellet) with an electrical conductivity one order lower than that of Cu(TCNQ). The salt releases iodine by annealing to regenerate the original phases of Cu(TCNQ) via an intermediate Cu(TCNQ) I state. A solid-state reaction of TCNQ, CuI, and iodine also produces the iodine-containing salt. The iodine absorption-desorption mechanism of Cu(TCNQ) differs from that of alkali-TCNQ salts that we reported previously.
ROYAL SOC CHEMISTRY, Feb. 2014, New J. Chem., 38 (2), 739 - 743, English[Refereed]
Scientific journal
- 2014, JPS conf. Proc., 3, 013010-1 - 013010-6, English
[Refereed]
International conference proceedings
We have successfully prepared nanoribbons of blue potassium molybdenum bronze (K0.3MoO3) from hydrogen molybdenum bronze (H0.3MoO3) by using crystallite splitting induced by solid-phase transformation and subsequent selective growth under hydrothermal conditions. The obtained nanoribbons were single crystals with a size of ca. 100 mu m x 100 nm x 10 nm, well-elongated to the crystal b axis that corresponds to the conduction direction as a quasi-one-dimensional metal. A simple. deaeration procedure necessary for preparing a single phase of blue potassium bronze is also given.
CHEMICAL SOC JAPAN, Dec. 2013, Chemistry Letters, 42 (12), 1514 - 1516, EnglishScientific journal
We report a novel insulator-insulator transition arising from the internal charge degrees of freedom in the two-dimensional quarter-filled organic salt beta-(meso-DMBEDT-TTF)(2)PF6. The optical conductivity spectra above T-c = 70 K display a prominent feature of the dimer Mott insulator, characterized by a substantial growth of a dimer peak near 0.6 eV with decreasing temperature. The dimer peak growth is rapidly quenched as soon as a peak of the charge order appears below T-c, indicating a competition between the two insulating phases. Our infrared imaging spectroscopy has further revealed a spatially competitive electronic phase far below T-c, suggesting a nature of quantum phase transition driven by material-parameter variations.
AMER PHYSICAL SOC, Nov. 2013, Phys. Rev. Lett., 111 (21), 1 - 217801, English[Refereed]
Scientific journal
A thermochromic magnetic ionic liquid containing a cationic iron(iii) Schiff-base complex has been developed, whose color and magnetic moment change with temperature because of spin crossover in the liquid state. This spin-crossover behavior closely resembles that of a solid having the same cation. © The Royal Society of Chemistry.
Royal Society of Chemistry, Sep. 2013, Chem. Commun., 49 (69), 7662 - 7664, English[Refereed]
Scientific journal
The physicochemical properties of a series of the six-coordinated iron(III) diazaporphyrinate complexes, [Fe(DAzP)L2]± where the axial ligands (L) are DMAP, CN-, HIm, Py, 3-ClPy, 4-CNPy, 3-CNPy, 3,5-Cl2Py, THF, have been examined by combined analyses of NMR, EPR, Mössbauer spectrometry, and SQUID magnetometry. The solution and solid-state studies clarified that the complexes with 3-ClPy, 4-CNPy, 3-CNPy, 3,5-Cl2Py are in the less common spin-crossover process between S = 3/2 and S = 1/2 during the temperature change. The results clearly indicate that the complexes showed the switching behaviors of the electronic structure or the magnetic properties responsive to the external stimuli. © 2013 Elsevier Ltd. All rights reserved.
Feb. 2013, Polyhedron, 66, 60 - 64, English[Refereed]
Scientific journal
Purely organic materials are generally insulating. Some charge-carrier generation, however, can provide them with electrical conductivity. In multi-component organic systems, carrier generation by intermolecular charge transfer has given many molecular metals. By contrast, in purely organic single-component systems, metallic states have rarely been realized although some neutral-radical semiconductors have been reported. Here we uncover a new type of purely organic single-component molecular conductor by utilizing strong hydrogen-bonding interactions between tetrathiafulvalene-based electron-donor molecules. These conductors are composed of highly symmetric molecular units constructed by the strong intra-unit hydrogen bond. Moreover, we demonstrate that, in this system, charge carriers are produced by the partial oxidation of the donor molecules and delocalized through the formation of the symmetric intra-unit hydrogen bonds. As a result, our conductors show the highest room-temperature electrical conductivity and the metallic state under the lowest physical pressure among the purely organic single-component systems, to our knowledge. © 2013 Macmillan Publishers Limited. All rights reserved.
Jan. 2013, Nat. Commun., 4, English[Refereed]
Scientific journal
Vapor- and gas-responsive ionic liquids (ILs) comprised of cationic metal-chelate complexes and bis(trifluoromethanesulfonyl)imide (Tf2N) have been prepared, namely, [Cu(acac)(BuMe3en)][Tf2N] (1?a), [Cu(Bu-acac)(BuMe3en)][Tf2N] (1?b), [Cu(C12-acac)(Me4en)][Tf2N] (1?c), [Cu(acac)(Me4en)][Tf2N] (1?d), and [Ni(acac)(BuMe3en)][Tf2N] (2?a) (acac=acetylacetonate, Bu-acac=3-butyl-2,4-pentanedionate, C12-acac=3-dodecyl-2,4-pentanedionate, BuMe3en=N-butyl-N,N',N'-tetramethylethylenediamine, and Me4en=N,N,N',N'-trimethylethylenediamine). These ILs exhibited reversible changes in color, thermal properties, and magnetic properties in response to organic vapors and gases. The CuII-containing ILs are purple and turn blue-purple to green when exposed to organic vapors, such as acetonitrile, methanol, and DMSO, or ammonia gas. The color change is based on the coordination of the vapor molecules to the cation, and the resultant colors depend on the coordination strength (donor number, DN) of the vapor molecules. The vapor absorption caused changes in the melting points and viscosities, leading to alteration in the phase behaviors. The IL with a long alkyl chain (1?d) transitioned from a purple solid to a brown liquid at its melting point. The NiII-containing IL (2?a) is a dark red diamagnetic liquid, which turned into a green paramagnetic liquid by absorbing vapors with high DN. Based on the equilibrium shift from four- to six-coordinated species, the liquid exhibited thermochromism and temperature-dependent magnetic susceptibility after absorbing methanol.
WILEY-V C H VERLAG GMBH, Sep. 2012, Chem. Eur. J., 18 (38), 11929 - 11936, English[Refereed]
Scientific journal
Alkali metal salts of 7,7',8,8'-tetracyanoquinodimethane (TCNQ) reversibly absorb iodine forming the ternary salts M(TCNQ)I (M = Li, Na, K) and M-2(TCNQ)(3)I-2 (M = Rb). The ternary salts are also obtained by solid-state reactions of TCNQ with alkali iodides. These salts are paramagnetic and have high electrical conductivities, similar to 10(-1) S cm(-1), for compacted pellets, whereas the alkali metal salts of TCNQ are diamagnetic insulators. The ternary salts further absorb iodine to give over-doped salts M(TCNQ)I-n (n approximate to 6, M = Na, K), which gradually release iodine to give M(TCNQ)I. In contrast, the solid-state reaction of F(4)TCNQ and sodium iodide produces Na(F(4)TCNQ), which does not exhibit iodine absorption.
ROYAL SOC CHEMISTRY, May 2012, J. Mater. Chem., 22 (17), 8361 - 8366, English[Refereed]
Scientific journal
This review describes the switching behaviors of the electronic structure, which were observed in iron(III) porphyrinoids, by the addition of external stimuli. The combined analysis by various methods, such as EPR, Mossbauer, SQUID, single crystal X-ray structure analysis, revealed a wide variety of electronic structures of the heme related complexes. This paper focuses in particular on the spin-crossover phenomenon in the solid state. An overview of spin-crossover phenomena found in iron(III) porphyrinoids between (i) S = 5/2 and S = 1/2, (ii) S = 3/2 and S = 1/2, (iii) S = 5/2 and S = 3/2, will be described.
SPRINGER, Mar. 2012, Hyperfine Interact., 206 (1-3), 23 - 33, English[Refereed]
Scientific journal
Novel polymorph of the ferric spin crossover complex, beta-[Fe(qsal)(2)]I-3 [qsalH = N-(8-quinolyl) salicylaldimine], has been prepared and characterized by magnetic susceptibilities and Mossbauer spectra. beta polymorph exhibited a cooperative complete spin transition with a thermal hysteresis of 25 K and a tendency to be quenched in the high-spin (HS) state, which is contrastive to a gradual incomplete spin conversion in alpha polymorph.
SPRINGER, Mar. 2012, Hyperfine Interact., 206 (1-3), 1 - 5, English[Refereed]
Scientific journal
Catechol-fused tetrathiafulvalene (TIT) derivatives have been designed and synthesized as a new type of pi-electron donor molecules having two phenolic hydroxyl groups. Cyclic voltammetry measurements and quantum chemical calculations demonstrated the electronic effect of the direct fusion of the catechol unit to the TTF pi-skeleton. In the charge-transfer (CT) salts with bromide or chloride anions, a one-dimensional hydrogen-bonded chain was formed by the intermolecular OH center dot center dot center dot X network between the catechol moieties and the halide anions. The slight dissimilarity of the hydrogen-bond distances for the two CT salts gave rise to the significant differences in their overall molecular arrangements and intermolecular interactions as well as the electrical resistivities. (c) 2012 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, 2012, Tetrahedron Lett., 53 (33), 4385 - 4388, English[Refereed]
Scientific journal
The metallic state of the molecular conductor beta-(meso-DMBEDT-TTF)(2)X (DMBEDT-TTF = 2-(5,6-dihydro-1,3-dithiolo[4,5-b][1,4] dithiin-2-ylidene)-5,6-dihydro5,6-dimethyl-1,3-dithiolo[4,5-b][1,4]dithiin, X = PF6, AsF6) is transformed into the checkerboard-type charge-ordered state at around 75-80 K with accompanying metal-insulator (MI) transition on the anisotropic triangular lattice. With lowering temperatures, the magnetic susceptibility decreases gradually and reveals a sudden drop at the MI transition. By applying pressure, the charge-ordered state is suppressed and superconductivity appears in beta-(meso-DMBEDT-TTF)(2)AsF6 as well as in the reported beta-(meso-DMBEDT-TTF)(2)PF6. The charge-ordered spin-gapped state and the pressure-induced superconducting state are discussed through the paired-electron crystal (PEC) model, where the spin-bonded electron pairs stay and become mobile in the crystal, namely the valence-bond solid (VBS) and the resonant valence bonded (RVB) state in the quarter-filled band structure.
MDPI AG, 2012, Crystals, 2 (4), 1502 - 1513, English[Refereed]
Scientific journal
The synthesis of enantiopure donors (R, R) and (S, S)-vic-bis(hydroxymethyl)-BEDT-TTF (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) and the crystal structure of novel chiral crystal alpha'-[(S, S)-vic-bis(hydroxymethyl)-BEDT-TTF](2)ClO4 is described. The charge transfer complex is chiral with the polar space group P2, which affords the possibility of pyroelectricity. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
WILEY-V C H VERLAG GMBH, 2012, Phys. Status Solidi C, 9 (5), 1146 - 1148, English[Refereed]
Scientific journal
A unique N+-H center dot center dot center dot N hydrogen-bonded (H-bonded) dimer motif based on partially oxidized pyridyl-substituted TTF was constructed in the charge-transfer complex. The charge ordering in the TTF column by the charge disproportionation in the dimer regulates the arrangement of the H-bonded proton, evidencing the proton-electron coupled state.
ROYAL SOC CHEMISTRY, 2012, Chem. Commun., 48 (69), 8673 - 8675, English[Refereed]
Scientific journal
The synthesis, crystal and electronic structures, resistivity, magnetic susceptibility, and dielectric constant of the novel chiral crystal, alpha'-(S,S-DMBEDT-TTF)(2)PF6 [DMBEDT-TTF = dimethylbis(ethylenedithio) tetrathiafulvalene] are presented. The alpha'-type donor arrangement affords the one-dimensional antiferromagnetic behavior with J = -40 K. The calculated band structure indicates the pseudo-one-dimensional interaction in the molecular side-by-side direction along the b-axis. The frequency-dependent dielectric constant suggests the charge disproportionation above 100K. The non-centrosymmetric space group due to the composed chiral molecules affords the possibility of piezoelectricity. (C) 2011 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE SA, Aug. 2011, Synth. Met., 161 (15-16), 1563 - 1565, English[Refereed]
Scientific journal
(BTM-TS-TTP)(4)PF6, where BTM-TS-TTP is 2-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-5-(1,3-diselenol-2-ylidene)-1,3,4,6-tetrathiapentalene, has been prepared. An X-ray structure analysis reveals that it has a lambda-type array of the donors. It exhibited metallic conducting behavior down to 5 K.
CHEMICAL SOC JAPAN, 2011, Bulletin of the Chemical Society of Japan, 84 (1), 79 - 81, English[Refereed]
Scientific journal
- 2011, ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES, 67, C427 - C428
[Refereed]
A novel Fe(III) spin crossover (SCO) complex with a linear I(3) anion [Fe(qsal)(2)]I(3) 1 [qsalH=N-(8-quinolyl)-salicylaldimine] was prepared and characterized by the magnetic susceptibilities and crystal structures 1 exhibited a gradual SCO conversion (T(SCO)= ca 240 K) The crystal structural analyses for 1 at 50 and 293 K revealed that the two-dimensional (2D) network was constructed by intermolecular pi-pi interactions between pi-ligands of an Fe(III) cation Since the related complex [Fe(qsal)(2)]NCS 2 was known to show a cooperative SCO transition the crystal structure of 2 at 293 K was also determined 2 possessed 2D SCO cation arrangement similar to 1 whereas potential pi-pi interactions between 2D networks in 2 existed The dimensionality of intermolecular interactions was closely related to SCO behaviors and pressure effects on SCO compounds (C) 2009 Elsevier B V All rights reserved
ELSEVIER SCIENCE BV, 01 Jun. 2010, PHYSICA B-CONDENSED MATTER, 405 (11), S65 - S68, English[Refereed]
Scientific journal
A supramolecular copper complex, [Cu(I)Cl0.2Br1.3(pyra-TTF)(0.5+)] (4) (pyra-TTF = pyrazino-tetrathiafulvalene), was synthesized by a coordination of the assembled oxidized donor ligands as the conduction paths and the disordered mixed halide anion ligands. The one-dimensional complex 4 reveals the metallic behavior down to 190 K with a resistivity minimum at 250 K and transforms to semiconducting behavior by the CDW (charge density wave) transition at 190 K with the doubling of the donor stacking c-axis. However, the complete singlet state is prohibited by the rigid 1D copper halide framework, [CuCl0.2Br1.3](n).
ROYAL SOC CHEMISTRY, 2010, JOURNAL OF MATERIALS CHEMISTRY, 20 (45), 10130 - 10134, English[Refereed]
Scientific journal
<p>A novel spin-crossover molecular conductor, [Fe(qnal)<sub>2</sub>][Pd(dmit)<sub>2</sub>]<sub>5</sub>·acetone, was prepared and characterized. The crystal structural analyses of both the low- and high-temperature phases revealed that the supramolecular π-π interactions between the spin-crossover Fe(qnal)<sub>2</sub> cations as well as the cation contraction play an important role in the uniaxial lattice deformation which will modulate the electrical conductivity of the conducting Pd(dmit)<sub>2</sub> layer. Copyright © 2008 American Chemical Society.</p>
AMER CHEMICAL SOC, 28 May 2008, Journal of the American Chemical Society, 130 (21), 6688 - 6689, EnglishScientific journal
New supramolecular copper complexes with pyrazinotetrathiafulvalene (pyra-TTF) as the ligand, [(CUCl2)-Cl-II(pyraTTF)] (1) and (pyra-TTF)(2)[(CU3Cl4)-Cl-I(pyra-TTF)] (2), have been synthesized by- the diffusion method. Complex 1 is a black block crystal with a three-dimensional (3-D) supramolecular network; the linear chain [-(CUCl2)-Cl-II-(pyra-TTF)-](n) extends along the b axis, where the coordinated pyra-TTF donors are stacked in a head-to-tail and ring-over-bond configuration to construct two-dimensional (2-D) sheets, and between the sheets, there are C center dot center dot center dot Cl- or H center dot center dot center dot Cl- contacts. Even though the electron spin resonance (ESR) measurement reveals the nearly Cu-II state, complex 1 is a semiconductor with sigma(RT) = 1.0 X 10(-4) S cm(-1) and E-a = 0.33 eV. The high-frequency conductivity measurement also confirmed the intrinsic slight carrier doping from Cu-II to the pyra-TTF donor. This slight doping enhances not only the real and imaginary dielectric constants but also the antiferromagnetic interaction between Cu-II spins following the 2-D Heisenberg model with 2J = -20 K. In contrast, complex 2 is a very thin black needle. This needle crystal has two crystailographically independent pyra-TTF molecules, which are coordinated and noncoordinated donors. The coordinated donors composed a supramolecular chain [(Cu3Cl4)-Cl-I(pyra-TTF)(0)](n), whereas the noncoordinated donors formed conducting alpha ''-type pyra-TTF+0.5 sheets. This complex is semiconducting with sigma(RT) = 0.1 S cm(-1) and E-a = 0.15 eV. Both complexes 1 and 2 demonstrate that the pyra-TTF molecule works not only as an oxidized donor by Cu-II to construct conducting sheets but also as a ligand coordinated to a Cu cation to form supramolecuar chains.
AMER CHEMICAL SOC, 19 May 2008, INORGANIC CHEMISTRY, 47 (10), 4140 - 4145, English[Refereed]
Scientific journal
<p>The synergy between the electrical conductivity within the stacks of Ni(dmit)<sub>2</sub> in the newly electrocrystallized [Fe(qsal) <sub>2</sub>][Ni(dmit)<sub>2</sub>]<sub>3</sub>· CH<sub>3</sub>CN· H<sub>2</sub>O and the spin conversion of Fe(qsal)<sub>2</sub> is evidenced. In addition, the presence of a light-induced excited spin state trapping effect suggests that this complex is a prototypal photoswitchable spin-crossover molecular conductor. © 2006 American Chemical Society.</p>
AMER CHEMICAL SOC, 24 Jul. 2006, Inorg. Chem., 45 (15), 5739 - 5741, EnglishScientific journal
<p>The Ni(dmit) <sub>2</sub> salt with an Fe(III) spin-crossover cation, Fe(qsal)2, was prepared and showed a cooperative spin transition based on π-π interactions between π-ligands. The light-induced excited spin state trapping effect on this complex was also observed. Copyright © 2005 The Chemical Society of Japan.</p>
05 Sep. 2005, Chem. Lett., 34 (9), 1240 - 1241, EnglishScientific journal
The conducting materials based on 2-(1,3-dithiol-2-ylidene)-5-(pyran-4-ylidene)-1,3,4,6-tetrathiapentalene (PDT-TTP) and its thiopyran and/or selenium analogues have been developed. The ethylenedithio derivative (ET-PDT) affords 4:1 salt with PF6- anion (ET-PDT)(4)PF6(cn) (cn = 1-chloronaphthalene). It has the so-called lambda-type array of the donors with quasi one-dimensional electronic structure due to strongly tetramerized stack. On the other hand, (TM-TPDS)(2)AsF6 adopt the "windmill type" array of the donors. In this salt, relatively large side-to-edge interactions stabilize their electronic structure, while effective side-by-side interaction is inhibited by methythio groups projected along the molecular short axis. In contrast, edge-to-edge interactions are dominant in (SM-PDT)PF6(PhCl)(x) through selenium-selenium contacts along the molecular long axis. (ET-PDT)(4)PF6(cn) shows metallic conductivity down to 1.5 K, while (TM-TPDS)(2)AsF6 is in organic metal exhibiting M1 transition at 100 K. On the other hand, (SM-PDT)PF6(PhCl)(x) is a semiconductor with relatively high conduuctivity of sigma = 4.8 S cm(-1) in spite of 1: 1 composition.
E D P SCIENCES, Apr. 2004, Journal De Physique. IV : JP, 114, 431 - 437, English[Refereed]
Scientific journal
Derivatives of dimeric BDT-TTP (2,5-bis(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene), in which two BDT-TTP units are linked by 1,3-propylenedithio (1) or 1,4-butylenedithio (2) group, have been synthesized. Cyclic voltammograms of 1 and 2 exhibit four pairs of two-electron redox waves, although the redox wave at the lowest voltage region is slightly broad. This result indicates there is small intradimer interaction in the oxidation states.
ELSEVIER SCIENCE SA, 04 Apr. 2003, Synthetic Metals, 137 (1-3), 937 - 938, English[Refereed]
Scientific journal
Several derivatives of new TTP type donor composed of 2,2'-ethanediylidenebis(1,3-dithiole) and 2-(pyran-4-ylidene)-1,3-dithiole (1) and its thiopyrane analog (2) have been synthesized. Cyclic voltammograms of 1 and 2 consist of four pairs of single-electron redox waves. They afford highly conducting TCNQ complexes and I-3(-) salts (sigma(rt) = 10(-2) - 10(0) S cm(-1) on a compressed pellet), which exhibit semiconducting temperature dependence with relatively low activation energy of 0.030 - 0.081 eV.
ELSEVIER SCIENCE SA, 04 Apr. 2003, Synthetic Metals, 135 (1-3), 671 - 672, English[Refereed]
Scientific journal
In our preceding paper, we have reported that a Co complex, [Co III-LS (tmeda)(3, 5-DBSQ)(3, 5-DBCat)]· 0.5C 6 H 5 CH 3 , exhibits a photo-induced valence tautomerism. The photo-induced metastable state, [Co II-HS (tmeda) (3, 5-DBSQ) 2 ]· 0.5C 6 H 5 CH 3 , has a back electron transfer band from Co II-HS to 3,5-DBSQ at around 800 nm, indicating that the valence tautomerism should be photo-reversible. In fact, we have found that the metastable state could be photo-pumped back to the original state by exciting the back electron transfer band. The process can be expressed as [Co II-HS (tmeda)(3, 5-DBSQ) 2 ] · 0.5C 6 H 5 CH 3 (metastable state) → [Co III-LS (tmeda)(3, 5-DBSQ)(3, 5-DBCat)] · 0.5C 6 H 5 CH 3 (ground state). © 2002 Published by Elsevier Science B.V.
ELSEVIER SCIENCE BV, 25 Mar. 2002, Chemical Physics Letters, 355 (1/2), 169 - 174, EnglishScientific journal
A new tetrathiapentalene (TTP) type donor, 2-(2-cyclohexenediylidene-1,3-dithiole)-5-(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene (CHDTDT), has been prepared. Cyclic voltammogram of CHDTDT showed three pairs of redox waves at 0.00 (2e), +0.42 (1e) and +0.66 (1e) V (vs, Ag/Ag+, in PhCN). CHDTDT has yielded several metallic radical cation salts. Among them, the AsF6 salt exhibited metallic conductivity down to 4.2 K.
TAYLOR & FRANCIS LTD, 2002, Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals, 380, 151 - 155, English[Refereed]
Scientific journal
Several copper and platinum complexes with TTP (2,5-bis(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene) dithlolato ligands, Cu(ttpdt)(2) (1) and Pt(ttpdt)(bpy) (2), have been prepared. The tetrakis(ethylthio) and tetrakis(hexylthio) derivatives of neutral Cu(ttpdt)2 showed relatively high conductivity of sigma(rt) = 10(-2) S cm(-1) on compressed pellets. On the other hand, radical cation salts of 1 and 2 exhibited moderate conductivity of sigma(rt) = 10(-2) -10(-4) S cm(-1).
TAYLOR & FRANCIS LTD, 2002, Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals, 379, 71 - 76, English[Refereed]
Scientific journal
Several TM-PDT analogous donors, where TM-PDT is 2-[4,5-bis(thiomethyl)-1,3-dithiol-2-ylidene]-5-(pyran-4-ylidene)-1,3,4,6-tetrathiapentalene, have been prepared. Cyclic voltammetry demonstrated that chalcogen atom exchange at chalcogenopyran moiety in donors strongly influenced their redox potentials. Electrical conductivity of all their salts showed a semiconducting behavior with relatively small activation energy. Crystal structure of (SM-PDT)(TCNQ), where TM-PDT is 2-[4,5-bis(selenomethyl)-1,3-dithiol-2-ylidene]-5-(pyran-4-ylidene)-1,3,4,6-tetrathiapentalene, has been revealed to compose of the D-A type mixed stacks.
TAYLOR & FRANCIS LTD, 2002, Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals, 376, 107 - 112, English[Refereed]
Scientific journal
Photo-illumination effects have been measured for the compound [Co III-LS (tmpda)(3,6-DBSQ)(3,6-DBCat)]. When the aforementioned compound was illuminated at 5K, the magnetization value increased from μ eff =1.87 to 2.03 μ B . The absorption spectra after illumination show that the absorption band at around 730 nm, which is characteristic of the [Co II-HS (tmpda)(3,6-DBSQ) 2 ] state, increased in intensity and that the charge transfer band from 3,6-DBCat to 3,6-DBSQ at 2500 nm was reduced in intensity. IR spectra show that the C-O stretching peak at 1279cm -1 is decreased in intensity. These results confirm that a photo-induced intra-molecular electron transfer, [Co III-LS (tmpda)(3,6-DBSQ)(3,6-DBCat)]→[Co II-HS (tmpda) (3,6-DBSQ) 2 ], was induced. The lifetime of the metastable state at 5 K was 15min. Furthermore, it was found that reverse valence tautomerism can be induced by exciting the Co II-HS to 3,6-DBSQ charge transfer band in metastable [Co II-HS (tmpda)(3,6-DBSQ) 2 ].
TAYLOR & FRANCIS LTD, 01 Jan. 2002, Phase Transitions, 75 (7-8), 779 - 785, EnglishScientific journal
Six kinds of novel TTP derivatives including BETS skeleton (1a-1f) have been prepared. The crystal structures of (1b)(SbF6)(0.36) and (1c)(Au(CN)(2))(0.36) were determined and these donor arrangements are so-called kappa -type. Temperature dependence of resistivity of (1f)(SbF6)(0.32) revealed selenium atom substitution may suppress a metal-insulator transition.
ELSEVIER SCIENCE SA, 15 Mar. 2001, Synthetic Metals, 120 (1-3), 955 - 956, English[Refereed]
Scientific journal
The electric-field-Induced metastable state of the checkerboard-type charge-ordered molecular conductor beta-(meso-DMBEDT-TTF)(2)PF6 was analyzed by the comparison of the experimental results of V-sample(t) measurement with the simulated behavior utilizing the self-heating effect The fast resistance drop and the appearance of metastable state are confirmed to be non-thermal but electric-field responses Moreover the Raman spectroscopy measurement indicates that the electric-field-induced metastable state is the homogeneous charge-fluctuated state (C) 2009 Elsevier B V All rights reserved
ELSEVIER SCIENCE BV, Jun. 2010, PHYSICA B-CONDENSED MATTER, 405 (11), S37 - S40, English[Refereed]
Scientific journal
A novel Fe(III) spin-crossover complex, [Fe(qsal)(2)][Ni(dmise)(2)] center dot 2CH(3)CN 1 [qsalH = N-(8-quinolyl)-salicylaldimine, dmise = 4,5-dithiolato-1,3-dithiole-2-selone] was prepared. The magnetic susceptibility measurements revealed 1 exhibited a cooperative spin transition with a thermal hysteresis loop of 15 K. The high and the low temperature structures of 1 indicated three-dimensional intermolecular pi-pi interactions play a key role in the cooperative spin transition, accompanying a reversible molecular slipping of pi-dimer of Ni(dmise)(2) along the molecular long axis. The transfer integral calculation for 1 suggested the pi-dimer of Ni(dmise)(2) is in the spin singlet state. (C) 2008 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, Jun. 2009, POLYHEDRON, 28 (9-10), 1776 - 1781, English[Refereed]
Scientific journal
(TTP-PROXYL)FeCl4, where TTP-PROXYL is 2,5-bis(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene (TTP) incorporating the 2,2,5,5-tetramethyl-1-pyrrolidinyloxy (PROXYL) radical, is a semiconductor with two kinds of localized spin systems, that is, the systems of organic radical spins and 3d spins of magnetic FeCl4- ions. The 7 spin of the TTP-PROXYL radical cation disappears due to dimerization but the chi T-value of 4.65 Kemu mol(-1) indicates the coexistence of high-spin Fe3+ (S = 5/2) and PROXYL radical (S = 1/2) ill this salt. (TTP-PROXYL)GaCl4 is isostructural to the FeCl4 salt and exhibited similar semiconducting properties.
CHEMICAL SOC JAPAN, Jan. 2006, CHEMISTRY LETTERS, 35 (1), 130 - 131, English[Refereed]
Scientific journal
- Photo-induced valence tautomerism in a Co compound
Photo-illumination effects have been measured for [CoIII-LS(tmeda)(3,5-DBSQ)(3,5-DBCat)1-0.5C(6)H(5)CH(3), where LS, tmeda, 3,5-DBSQ and 3,5-DBCat denote low-spin, N,N,N',N'-tetramethylethylenediamine, 3,5-di-tert-butyl-1,2-semiquinonate and 3,5-di-tert-butyl-1,2-catecholate, respectively. When the title compound was illuminated at 5 K, the magnetization value increased from mu(eff) = 1.7 to 2.3 mu(B). The absorption spectra after illumination show that the absorption band at around 800 nm, characteristic of the [CoII-HS (tmeda)(3,5-DBSQ)21 state (HS denotes high-spin), increased and the charge transfer band from 3,5-DBCat to 3,5-DBSQ at 2500 nm was reduced. IR spectra show that the C-O stretching peak at 1280 cm(-1) is significantly decreased. These results confirm that a photo-induced intra-molecular electron transfer, [CoIII-LS(tmeda)(3,5-DBSQ)(3,5-DBCat)] --> [CoII-HS(tmeda)(3,5-DBSQ)(2)], was induced. The lifetime of the metastable state at 5 K was 175 min. (C) 2002 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE SA, Jun. 2002, JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY, 149 (1-3), 111 - 114, English[Refereed]
Scientific journal
- A novel coordination polymer derived from thiophene-fused DCNQI and CuI: A new family of DCNQI based conducting copper complexes
Thiophene-fused DCNQI compounds yield conducting CuI complexes built up of a unique three-dimensional supramolecular coordination structure in which the zigzag ladder CuI polymers are bridged by the pi-stacked accepters as a bidentate ligand.
Lead, ROYAL SOC CHEMISTRY, Oct. 1996, CHEMICAL COMMUNICATIONS, (19), 2275 - 2276, English[Refereed]
Scientific journal
- Conducting polynuclear CuI complexes with thiophene-fused DCNQI ligands
New derivatives of thiophene-fused DCNQI and their CuI complexes have been prepared. Among those, beta,beta'-dimethyl derivative (2) afforded a single crystal of complex (2)(CuI), suited for an X-ray analysis and its crystal structure has been determined. The structure is built up of the zigzag ladder of CuI polymer. Bidentate ligand molecules of 2 bridge the CuI ladders by coordinating the CN group to Cu of the ladder. The acceptor pi-plane is arranged face-to-face with interplanar distance of 3.56 Angstrom. The room temperature conductivity of (2)(CuI)(2) was 7.6 X 10(-3) Scm(-1) with semiconductive behavior in the temperature dependent conductivity.
GORDON BREACH SCI PUBL LTD, 1996, MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY SECTION A-MOLECULAR CRYSTALS AND LIQUID CRYSTALS, 285, 175 - 180, English[Refereed]
Scientific journal
- American Chemical Society (ACS), 08 Sep. 2020, Inorganic Chemistry, 59 (17), 12295 - 12303, English, International magazine
[Refereed]
Scientific journal
The magnetostructural correlation was investigated in three organic radical cation salts based on the monocation of benzo[1, 2-d:4, 5-d']bis[1, 3, 2]dithiazolyl (BBDTA), which is an S = 1/2 system, and the tetrahedral diamagnetic monoanions, TlBr4- (1), TlI4 - (2), and InI4- (3), by analysis of their crystal structures and magnetic properties. X-ray diffraction studies showed that these three salts consisted of alternatively stacked layers of the diamagnetic anions layers and the organic cation layers in which BBDTA + formed a square planar lattice, which is rare in organic radical crystals. 1 exhibited canted antiferromagnetism with an antiferromagnetic interaction in the organic cation layer below 11.6 K, whereas 2 and 3 showed metamagnetism with a ferromagnetic interaction in the organic cation layer below 8.9 and 11.3 K, respectively. Their intra-and interlayer magnetic coupling constants, 2J/kB and zJ'/kB, were estimated to be-11.2 and-4.1 K for 1,+11.4 and-3.7 K for 2, and + 12.8 and-2.3 K for 3, respectively, using a two-dimensional square planar S=1/2 Heisenberg model with mean field approximation. A consideration of the molecular orbitals showed that the differences in the intralayer magnetic interactions in 1 and, 2 or 3, originate in the molecular orientation of BBDTA+ in the organic cation layer. Overlap relation between the singly occupied molecular orbitals (SOMOs) of the nearest neighbor BBDTA+ pairs was found in 1, whereas an orthogonal relation was found in 2 and 3. © 2011 American Chemical Society.
02 Feb. 2011, Crystal Growth and Design, 11 (2), 575 - 582, English[Refereed]
Scientific journal
The frequency dependent dielectric response due to proton transfer is observed for the novel one-dimensional (1D) hydrogen-bonded co-crystal, [4,6-dmpH][Hca] (4,6-dmp=4,6-dimethylpyrimidine, ca=chloranilic acid). This response is only observed for an as-grown crystal in a metastable state with defects of hydrogen bonds. The critical hydrogen-bond length and one-dimensionality might be deeply related to the metstable state. © 2010 Elsevier B.V. All rights reserved.
Elsevier B.V., 01 Jun. 2010, Physica B: Condensed Matter, 405 (11), S341 - S343, English[Refereed]
International conference proceedings
The pressure dependence of resistivity for the checkerboard-type charge-ordered (CO) molecular conductor β- (meso-DMBEDT-TTF) 2 PF6 has been investigated. Under the low pressure of 0.6 kbar, the temperature of resistivity minimum (Tmin) falls from 90 K at an ambient pressure to 67 K, and after the resistivity has been increased, the superconducting (SC) transition is observed at 4.6 K. By applying magnetic field, the SC state is suppressed and the large positive magnetoresistance (MR) is demonstrated below Tmin in the CO state. Since the positive MR was observed even in the metallic state under high pressures, the summarized pressure-temperature (P-T) phase diagram reveals that the SC state neighbors to the CO-insulating and charge-fluctuated metallic states. © 2009 The American Physical Society.
28 Sep. 2009, Physical Review B - Condensed Matter and Materials Physics, 80 (9), English[Refereed]
Scientific journal
New copper complexes with Dmt-Pyra-STF (=dimethylthio-pyrazino-selenathiafulvalene) as the ligand-trans-[CuIICl2(Dmt-Pyra-STF)2] (1) and [CuI2Br2.5(Dmt-Pyra-STF)] (2)-have been synthesized by a vertical diffusion method. In complex 1, the donors form uniform stacking columns along the c axis to have a θ-type donor arrangement, but 1 is an insulator due to the absence of carriers. The magnetic susceptibility of 1 can be fitted to the Curie-Weiss rule (θ = -9.02 K) and suggests that the oxidation state of Cu ions in 1 is 2+. In contrast, complex 2 has supramolecular chains along the c axis, which are formed by CuI and Br-. In addition, this complex is a semiconductor with σrt = 0.16 S cm-1 and Ea = 0.10 eV. The magnetic susceptibility of 2 suggests that the oxidation state of Cu ions in 2 is 1+, namely [CuI2Br2.5(Dmt-Pyra-STF)0.5+]. Both complexes 1 and 2 demonstrate that pyrazino-fused STF derivatives can be coordinated to a copper even though the atomic orbital of Se is so large. Furthermore, we can firstly synthesize complex 2, in which both charge transfer and coordination occur simultaneously. © 2008 Elsevier Masson SAS. All rights reserved.
Dec. 2008, Solid State Sciences, 10 (12), 1724 - 1728, English[Refereed]
Scientific journal
Dielectric response and nonlinear conduction are studied in an organic conductor β-(meso-DMBEDT-TTF) 2PF6, which undergoes the metal-insulator transition caused by the checkerboard-type charge ordering (CCO). The formation of the long-range CCO (LR-CCO) was observed as a sudden increase in the dielectric constant below 70 K. Below 70 K, the I-V curve shows a remarkable negative differential resistance with a non-monotonous voltage drop, and its nonlinearity survives up to about 100 K. Timeresolved sample voltage data shows a steep drop followed by a transient plateau and a further drop into the most conductive state. The former steep voltage drop may cause the negative differential resistance in the I-V curve, while the transient plateau implies a metastable state induced by the electric field. ©2008 The Physical Society of Japan.
Jul. 2008, Journal of the Physical Society of Japan, 77 (7), English[Refereed]
Scientific journal
Photo-illumination effects have been measured for [CoIII-LS (phen)(3,5-DBSQ)(3,5-DBCat)]·C6H5Cl, where LS, phen, 3,5-DBSQ and 3,5-DBCat denote low-spin, 1,10-phenanthroline, 3,5-di- tert -butyl-1,2-semiquinonate and 3,5-di- tert -butyl-1,2-catecholate, respectively. When the Co compound was illuminated at 5 K, the magnetization value, μ eff increased from 1.7 to 2.7 μ B. The UV-Vis absorption spectra after illumination show that the absorption band at around 800 nm, characteristic of the [CoII-HS(phen) (3,5-DBSQ)2] state (HS denotes high-spin), increased and the charge transfer band from 3,5-DBCat to 3,5-DBSQ at 2500 nm was reduced. IR spectra show that the C-O stretching peak at 1280 cm-1 is significantly decreased. These results confirm that a photo-induced intra-molecular electron transfer, [CoIII-LS(phen)(3,5-DBSQ)(3,5-DBCat)]·C6 H5Cl↔[CoII-HS(phen)(3,5-DBSQ)2] ·C6H5Cl, was induced by 532 or 830 nm light. The relaxation kinetics of valence tautomerism was studied. For T≥25 K, kVT 0=0.205 s-1 and Ea=110.38 cm-1. Below 25 K, the rate constant for the valence tautomeric relaxation as T approaches the 0 K, which suggests that tunneling is the predominant mechanism for the relaxation. © 2004 Elsevier B.V. All rights reserved.
01 Oct. 2004, Journal of Photochemistry and Photobiology A: Chemistry, 167 (2-3), 69 - 73, English[Refereed]
Scientific journal
MISC
- 04 Aug. 2018, 応用物理・物理系学会中国四国支部合同学術講演会講演予稿集, 2018, 43, Japanese二核金属錯体[(Fe(RR‐cth)(Co(SS‐cth)(dhbq)](PF6)3のスピン‐電荷結合転移による自発電気分極
- MDPI Multidisciplinary Digital Publishing Institute, Mar. 2018, Inorganics, 6 (1), 32 (4 pages), English
[Refereed][Invited]
Introduction scientific journal
- 2018, 分子科学討論会講演プログラム&要旨(Web), 12th, ROMBUNNO.1D08 (WEB ONLY), Japaneseスピン‐電荷結合系二核金属錯体[Fe(RR‐cth)(Co(SS‐cth)(dhbq)](PF6)3における自発電気分極の焦電観測
Molecular crystalline materials that comprise pi-electron organic molecules exhibit various interesting physical properties and functionalities related to electrical conductivity and magnetic, dielectric, and optical properties. Their experimental and theoretical studies have extensively been performed by a wide range of researchers in the fields of organic chemistry, physical chemistry, solid-state physics, and so on. In particular, synthetic organic chemists have devoted continuous effort to the design and synthesis of new functional molecular crystals and component molecules, which led to numerous important discoveries in this interdisciplinary research field. Here we report the development of a new type of organic conductors based on catechol-fused tetrathiafulvalene (TTF) derivatives. Interestingly, dynamic properties of hydrogen bonds through the catechol moiety are coupled with pi-electrons on the TTF skeleton, which allowed us to discover unprecedented phase transitions, physical properties, and functionalities. In this paper, the design, synthesis, structures, and properties of our new molecules and crystals are described from a molecular point of view.
SOC SYNTHETIC ORGANIC CHEM JPN, Oct. 2017, Journal of Synthetic Organic Chemistry, Japan, 75 (10), 1045 - 1054, Japanese[Refereed]
Introduction scientific journal
- The Physical Society of Japan (JPS), 26 Aug. 2013, Meeting abstracts of the Physical Society of Japan, 68 (2), JapaneseUniversal Nature of Quantum Spin Liquid in Organic Triangular Lattices Probed by Torque Magnetometry
- The Physical Society of Japan (JPS), 24 Aug. 2012, Meeting abstracts of the Physical Society of Japan, 67 (2), Japanese20pEB-10 Possible spin-liquid state of a dimer-Mott insulator κ-H_3(Cat-EDT-TTF)_2
- 09 Mar. 2012, 日本化学会講演予稿集, 92nd (2), 304, Japaneseピリジル置換TTF誘導体を用いたプロトン性電荷移動錯体の構造と物性
- 09 Mar. 2012, 日本化学会講演予稿集, 92nd (2), 303, Japaneseカテコール縮環TTF Cat‐TTF誘導体を用いた水素結合を有するκ‐型単一成分電導体の作成,構造と物性
- 05 Mar. 2012, 日本物理学会講演概要集, 67 (1), 868, Japanese水素結合を有する新奇な単一成分κ型分子性伝導体の高圧物性
- 一般社団法人 日本物理学会, 2012, Meeting Abstracts of the Physical Society of Japan, 67 (0), Japanese18pEB-15 Infrared Imaging of the Organic Charge-Order Insulators β-(meso-DMBEDT-TTF)_2PF_6
- 一般社団法人 日本物理学会, 2012, Meeting Abstracts of the Physical Society of Japan, 67 (0), Japanese24pBK-6 Competition between Dimer-Mott and Charge-Order Insulators in β-(meso-DMBEDT-TTF)_2PF_6
- The Physical Society of Japan, 2010, Meeting Abstracts of the Physical Society of Japan, 65 (0), Japanese20aGT-4 Magnetoresistance and nonlinear conduction for α-(BEDT-TTF)_2I_3 and α'-(BEDT-TTF)_2IBr_2
- The Physical Society of Japan, 2009, Meeting Abstracts of the Physical Society of Japan, 64 (0), Japanese29pYF-3 Nonlinear conduction and giant magnetoresistance for α-(BEDT-TTF)_2I_3
The first preparation of an Fe(II) spin-crossover complex including a 1,3-dithiole ligand is reported. Crystal analyses of both the low- and the high-temperature phases reveal that short S ... S contacts play a key role in an abrupt spin transition.
ROYAL SOC CHEMISTRY, 2003, Chemical Communications, (18), 2374 - 2375, EnglishWe report the first observation of a color change from red to purple for a thermochromic complex, [Cu(dieten)(2)](BF4)(2) (dieten = N,N-diethylethylenediamine), which is induced by illuminating with UV light.
ROYAL SOC CHEMISTRY, 2002, Chemical Communications, (15), 1578 - 1579, EnglishNew families of extended tris-fused TTFs, in which aromatic rings are inserted, have been synthesized. Cyclic voltammetry and theoretical calculation of them indicate electronic structure of the furan and thiophene derivatives may be regarded as tris-fused TTFs, whereas the benzene derivative as a dimeric (2-methylidene- l,3-dithiolo[4,5-d])-TTF.
CHEMICAL SOC JAPAN, 2002, Chemistry Letters, (10), 1002 - 1003, EnglishThe title donor, where SM-PDT is 2-[4,5-bis(selenomethyl)-1,3-dithiol-2-ylidene]-5-(pyran4-ylidene)-1,2,4,6-tetrathiapental-ene, formed semiconducting I:I salts with various anions. The crystal structure analysis of (SM-PDT)PF6(PhCl)(x) has revealed that an edge-to-edge chalcogen interaction gave two-dimensional sheet-like structure.
CHEMICAL SOC JAPAN, 2001, Chemistry Letters, (2), 162 - 163, English- AMER CHEMICAL SOC, 2000, Journal of Organic Chemistry, 65 (8), 2577 - 2579, English
A new extended pi-conjugated TCNQ, hexacyanostilbenequinodimethane, was isolated as a dianion salt. Its cyclic voltammograms show that the dianion is reduced reversibly to a trianion radical, while the oxidized species, a monoradical anion, dimerizes to give the dimer dianion, which is further electrochemically oxidized to a neutral polymer. (C) 1999 Elsevier Science Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, 1999, Tetrahedron Letters, 40 (29), 5349 - 5352, English
Presentations
- 日本物理学会第75回年次大会, Mar. 2020, Japanese, 名古屋大学, Domestic conferenceS=1/2 反強磁性鎖KCuMoO4(OH)の単結晶ESR測定II
Poster presentation
- 日本化学会第100春季年会, Mar. 2020, Japanese, 東京理科大学野田キャンパス, Domestic conferenceメトホルミンからなる金属錯体の構造と性質
Oral presentation
- 日本化学会第100春季年会, Mar. 2020, Japanese, 東京理科大学野田キャンパス, Domestic conferenceアゾビスフェノレート誘導体を有する遷移金属錯体の構造と酸化還元特性
Oral presentation
- 日本化学会第100春季年会, Mar. 2020, Japanese, 東京理科大学野田キャンパス, Domestic conferenceアゾビスフェノレート鉄(III)錯体のスピン転移が誘起する結合異性現象
Oral presentation
- 日本化学会第100春季年会, Mar. 2020, Japanese, 東京理科大学野田キャンパス, Domestic conferenceスピンクロスオーバー(SCO)によって誘起される鉄(II)錯体の構造転移
Oral presentation
- 若手フロンティア研究会2019, 19 Dec. 2019, Japanese, 神戸大学百年記念館, Domestic conferenceスピン転移が誘起する新奇な結合異性
Poster presentation
- 若手フロンティア研究会2019, 19 Dec. 2019, Japanese, 神戸大学百年記念館, Domestic conference二種類の配位部位を持つ多座配位子錯体の配位構造制御
Poster presentation
- 若手フロンティア研究会2019, 19 Dec. 2019, Japanese, 神戸大学百年記念館, Domestic conference鉄(II)錯体におけるスピンクロスオーバー誘起構造転移
Poster presentation
- MRS-J第29回年次大会, 27 Nov. 2019, Japanese, 横浜万国会議センター, Domestic conference赤外領域光学スペクトルからみたスピンクロスオーバー相転移を起こす複合磁性材料における光誘起状態
Oral presentation
- 第28回有機結晶シンポジウム, 10 Nov. 2019, Japanese, 香川大学創造工学部林町キャンパス, Domestic conferenceピリジン環を有する多座配位子を用いた配位高分子錯体の合成および構造評価
Poster presentation
- 第28回有機結晶シンポジウム, 09 Nov. 2019, Japanese, 香川大学創造工学部林町キャンパス, Domestic conferenceアゾ配位子を有する鉄(III)錯体のスピン転移誘起結合異性
Oral presentation
- 第10回サイエンスフロンティア研究発表会, 26 Oct. 2019, Japanese, 神戸大学, Domestic conferenceアニオンのサイズ形状による鉄(II)スピンクロスオーバー錯体の磁気挙動の変化
Poster presentation
- 第10回サイエンスフロンティア研究発表会, 26 Oct. 2019, Japanese, 神戸大学, Domestic conference鉄(III)錯体のスピン転移に伴う結合異性化
Poster presentation
- 7th Asain conference on coordination chemistry, English, Kuala lumpur, Malaysia, International conferenceOptical study of the photo-induced state of the spin-crossover hybrid system
Poster presentation
- 13th International Symposium on Crystalline Organic Metals, Superconductors and Magnets, 24 Sep. 2019, English, Tomar, Portugal, International conferenceThe structure of the photoinduced state of the spin-crossover hybrid system
Poster presentation
- 錯体化学会第69回討論会, 21 Sep. 2019, 名古屋大学東山キャンパス, Domestic conference鉄(II)スピンクロスオーバー錯体における対アニオンのサイズ形状効果
Oral presentation
- 錯体化学会第69回討論会, 21 Sep. 2019, Japanese, 名古屋大学東山キャンパス, Domestic conferenceヘテロレプティック鉄(III)錯体のスピンクロスオー バー転移と配位子の結合異性
Oral presentation
- 第13回分子科学討論会, 20 Sep. 2019, Japanese, 名古屋大学, Domestic conference原子価互変異性金属錯体における電気分極の分光観測
Poster presentation
- 日本物理学会2019年秋季大会（物性）, 12 Sep. 2019, Japanese, 岐阜大学, Domestic conferenceS=1/2反強磁性鎖KCuMoO4(OH)の単結晶ESR測定
Oral presentation
- 日本物理学会2019年秋季大会（物性）, 12 Sep. 2019, Japanese, 岐阜大学, Domestic conference赤外領域光学スペクトルからみたスピンクロスオーバー相転移を起こす複合磁性材料における光誘起状態
Poster presentation
- 2019年日本物理学会2019年秋季大会（物性）, 11 Sep. 2019, Japanese, 岐阜大学, Domestic conferenceスピンクロスオーバー相転移を起こす複合磁性材料における光誘起状態の構造解析
Oral presentation
- 日本化学会 第99春季年会 (2019), Mar. 2019, Japanese, 甲南大学 岡本キャンパス, Domestic conference電荷を持つ鉄(II)錯体におけるスピンクロスオーバー挙動のアニオン効果
Oral presentation
- 日本化学会 第99春季年会 (2019), Mar. 2019, Japanese, 甲南大学 岡本キャンパス, Domestic conference多機能性配位子を用いた配位高分子の構造と物性
Oral presentation
- 日本化学会 第99春季年会 (2019), Mar. 2019, Japanese, 甲南大学 岡本キャンパス, Domestic conferenceπ拡張ヘテロレプティック鉄(III)スピンクロスオーバー錯体薄膜の評価
Oral presentation
- 日本化学会 第99春季年会 (2019), Mar. 2019, Japanese, 甲南大学 岡本キャンパス, Domestic conferenceヘテロレプティック鉄(III)スピンクロスオーバー錯体誘導体の構造と物性
Oral presentation
- 神戸大学 研究基盤センター 若手フロンティア研究会2018, Dec. 2018, Japanese, 神戸大学百年記念館, Domestic conference配位能を持つアクセプターからなる錯体の構造と性質
Poster presentation
- 神戸大学 研究基盤センター 若手フロンティア研究会2018, Dec. 2018, Japanese, 神戸大学百年記念館, Domestic conferenceスピンクロスオーバー錯体簿膜のFET特性
Poster presentation
- 第27回有機結晶シンポジウム, Oct. 2018, Japanese, 近畿大学東大阪キャンパス, Domestic conference中性ヘテロレプティック鉄（Ⅲ）錯体の結晶構造と磁気挙動への置換効果
Poster presentation
- 第27回有機結晶シンポジウム, Oct. 2018, Japanese, 近畿大学東大阪キャンパス, Domestic conferenceピリジン環を有する電子受容性配位子とその錯体の構造と物性
Poster presentation
- 第27回有機結晶シンポジウム, Oct. 2018, Japanese, 近畿大学東大阪キャンパス, Domestic conferenceスピンクロオーバー転移に与える格子エンタルピーの効果
Oral presentation
- 第12回分子科学討論会, Sep. 2018, Japanese, 福岡国際会議場, Domestic conferenceスピン-電荷結合系二核金属錯体[Fe(RR-cth)(Co(SS-cth)(dhbq)](PF6)3における自発電気分極の焦電観測
Oral presentation
- 日本物理学会2018秋季大会, Sep. 2018, Japanese, 同志社大学京田辺キャンパス, Domestic conferenceスピンクロスオーバー相転移を起こす複合磁性材料における光誘起状態の研究
Oral presentation
- 43rd International Conference on Coordination Chemistry, Aug. 2018, English, Sendai International Center, International conferenceContribution of non-covalent interactions to spin crossover compounds
Oral presentation
- 日本化学会第98春季年会（2018）, Mar. 2018, Japanese, 日本大学理工学部, Domestic conference含窒素芳香環を有する電子受容体を用いた新規分子性錯体の合成と性質
Oral presentation
- 日本化学会第98春季年会（2018）, Mar. 2018, Japanese, 日本大学理工学部, Domestic conferenceπ共役系配位子を有する中性鉄錯体の磁気的性質と電流-電圧特性
Oral presentation
- 第27回日本MRS年次大会, Dec. 2017, English, 万国橋会議センター, Domestic conferenceElectronic structure and photoinduced dynamics in the synergistic spin transition system
Oral presentation
- 日本物理学会 2017年秋季大会, Sep. 2017, Japanese, 岩手大学上田キャンパス, Domestic conference磁性‐非磁性相転移とスピンクロスオーバー転移が結合した複合分子系の電子構造及び光誘起ダイナミクス
Poster presentation
- 12th International Symposium on Crystalline Organic Metals, Superconductors and Magnets, Sep. 2017, English, Miyagi Zao Royal Hotel, International conferenceDevelopment of New π-Electron Acceptors with Aromatic N-Heterocycles
Poster presentation
- 日本化学会第97春季年会, Mar. 2017, Japanese, 慶應義塾大学 日吉キャンパス, Domestic conference新規中性ヘテロレプティック鉄錯体の構造と物性
Oral presentation
- 日本化学会第97春季年会, Mar. 2017, Japanese, 慶應義塾大学 日吉キャンパス, Domestic conference含窒素芳香環を有する新規π電子受容体の合成と性質
Oral presentation
- 第64回応用物理学会春季学術講演会, Mar. 2017, Japanese, パシフィコ横浜, Domestic conferenceMgO/Mg2Si/MgB2ナノ複合結晶の磁気異方性
Oral presentation
- 兵庫県立大学大学院物質理学研究科フロンティア機能物質創製センター第３回シンポジウム, Jan. 2017, Japanese, 兵庫県立大学播磨理学キャンパス, Domestic conference分子間相互作用を活かした機能性分子固体の創製
[Invited]
Invited oral presentation
- 若手フロンティア研究会2016, Dec. 2016, Japanese, KobeUniversity, Domestic conference新規電子受容性配位子の合成と性質
Poster presentation
- 若手フロンティア研究会2016, Dec. 2016, Japanese, KobeUniversity, Domestic conference新規中性ヘテロレプティック鉄(III)錯体の協同的転移
Poster presentation
- 第10回物性科学領域横断研究会, Dec. 2016, Japanese, KobeUniversity, Domestic conference新規中性ヘテロレプティック鉄(III)スピンクロスオーバー錯体の構造と物性
Poster presentation
- 第10回物性科学領域横断研究会, Dec. 2016, Japanese, KobeUniversity, Domestic conferenceπ電子受容性配位子およびその錯体の合成と物性
Poster presentation
- 第7回サイエンスフロンティア研究発表会, Oct. 2016, Japanese, 神戸大学, Domestic conference新規電子受容性配位子およびその錯体の構造と性質
Poster presentation
- 第7回サイエンスフロンティア研究発表会, Oct. 2016, Japanese, 神戸大学, Domestic conferenceπ拡張アニオン性スピンクロスオーバー錯体の合成と性質
Poster presentation
- 第７回イオン液体討論会, Oct. 2016, Japanese, 金沢市文化ホール, Domestic conferenceキレート錯体系クロモトロピックイオン液体の開発
Oral presentation
- 第25回有機結晶シンポジウム, Sep. 2016, Japanese, 京都大学, Domestic conference鉄(II)錯体の示す脱溶媒誘起結晶相転移とスピンクロスオーバー協同性との相関
Oral presentation
- 第10回分子科学討論会, Sep. 2016, Japanese, 神戸ファッションマート, Domestic conference新規電子受容性配位子の合成と錯形成の検討
Poster presentation
- 錯体化学会第66回討論会, Sep. 2016, Japanese, 福岡大学, Domestic conference新規π拡張スピンクロスオーバーアニオンを基盤とした複合機能性錯体の開発
Poster presentation
- 第25回有機結晶シンポジウム, Sep. 2016, Japanese, 京都大学, Domestic conference新規スピンクロスオーバーアニオンからなるプロトン性錯体の構造と物性
Poster presentation
- 第10回分子科学討論会, Sep. 2016, Japanese, 神戸ファッションマート, Domestic conference新奇アニオン性スピンクロスオーバー錯体のπ拡張誘導体の構造と物性
Oral presentation
- 日本セラミックス協会 第29回秋季シンポジウム, Sep. 2016, Japanese, 広島大学 東広島キャンパス, Domestic conference格子整合したヘテロ界面を有するMgO/Mg2Si/MgB2ナノ複合結晶の合成とその電気・磁気特性
Oral presentation
- 第10回分子科学討論会, Sep. 2016, Japanese, 神戸ファッションマート, Domestic conferenceニッケル錯体をカチオンとする磁性サーモクロミックイオン液体の開発
Poster presentation
- 第10回分子科学討論会, Sep. 2016, Japanese, 神戸ファッションマート, Domestic conferenceスピンクロスオーバー錯体における結晶転移と協同性との相関
Oral presentation
- The 15th International Conference on Molecule-Based Magnets, Sep. 2016, English, Sendai International Center, International conferenceSpin Crossover in Anionic Weak Ligand-Field Fe(III) Complexes
Poster presentation
- Post-ICMM Symposium2016, Sep. 2016, English, Fukuoka University, International conferenceOrigin and Functionalization of Novel Anionic Spin Crossover Complexes: Toward Development of the Multifunctional Compounds
Oral presentation
- 日本化学会第96春季年会, Mar. 2016, Japanese, Doshisha University, Domestic conference鉄(II)錯体の示す結晶水脱離に伴う構造転移とスピンクロスオーバー特性変化
Oral presentation
- 日本化学会第96春季年会, Mar. 2016, Japanese, Doshisha University, Domestic conference新規アニオン性スピンクロスオーバー錯体に与える配位子置換効果
Oral presentation
- 日本化学会第96春季年会(2016), Mar. 2016, Japanese, 同志社大学 京田辺キャンパス, Domestic conferenceニッケル錯体からなるサーモクロミックイオン液体の合成と物性
Oral presentation
- 神戸大学研究基盤センター「若手フロンティア研究会2015」, Dec. 2015, Japanese, Kobe University, Domestic conference銅(I)配位高分子の構造異性に基づく構造転移と発光挙動
Poster presentation
- 平成27年度神戸大学物性実験研究室セミナー, Dec. 2015, Japanese, 神戸大学瀧川記念学術交流会館, Domestic conference機能性スピンクロスオーバー錯体の開発
[Invited]
Invited oral presentation
- 神戸大学研究基盤センター「若手フロンティア研究会2015」, Dec. 2015, Japanese, Kobe University, Domestic conferenceアニオン性スピンクロスオーバー錯体に与えるπ拡張効果
Poster presentation
- Pacifichem 2015, Dec. 2015, English, Hawaii Convention Center, International conferenceRole of Intermolecular Interactions for Functional Spin Crossover Molecular Materials
Oral presentation
- The 65th Japan Society of Coordination Chemistry Symposium, Sep. 2015, Japanese, Nara Women's University, Domestic conference新規電子受容性配位子を用いた銅錯体の構造と性質
Oral presentation
- Annual Meeting of Japan Society for Molecular Science, Sep. 2015, Japanese, Tokyo Institute of Technology, Domestic conference新規アクセプター性配位子を用いた銅錯体の構造と発光挙動
Oral presentation
- The 65th Japan Society of Coordination Chemistry Symposium, Sep. 2015, Japanese, Nara Women's University, Domestic conferenceプロトンドナー配位子からなる鉄(II)スピンクロスオーバー錯体の構造と性質
Poster presentation
- 日本物理学会2015年秋季大会, Sep. 2015, Japanese, Kansai University, Domestic conferenceS=1/2擬1次元強磁性鎖CavanciteのESR測定法の開発
Oral presentation
- 日本化学会第95春季年会2015, Mar. 2015, Japanese, 公益社団法人 日本化学会, 日本大学 理工学部船橋キャンパス, Domestic conference新規アクセプター性配位子を用いた金属錯体の構造と性質
Oral presentation
- 日本化学会第95春季年会2015, Mar. 2015, Japanese, 公益社団法人 日本化学会, 日本大学 理工学部船橋キャンパス, Domestic conferenceハロゲン結合相互作用を導入した鉄(II)ハイブリッド錯体の構造と物性
Oral presentation
- 神戸大学研究基盤センター「若手フロンティア研究会2014」, Dec. 2014, Japanese, 神戸, Domestic conference磁性アニオンを含有した鉄(II)錯体の構造と磁気物性
Poster presentation
- 神戸大学研究基盤センター「若手フロンティア研究会2014」, Dec. 2014, Japanese, 神戸, Domestic conferenceハロゲン結合を持つスピンクロスオーバー伝導体の特異な構造転移
Poster presentation
- 短期研究会「有機固体化学の最前線」, Dec. 2014, Japanese, 愛媛大学, Domestic conferenceシナジー型スピンクロスオーバーハイブリッド材料の創製
Public discourse
- 第８回分子科学討論会2014, Sep. 2014, Japanese, 広島大学 東広島キャンパス, Domestic conference複合機能鉄（Ⅲ）スピンクロスオーバー錯体へのハロゲン置換効果
Oral presentation
- 第８回分子科学討論会2014, Sep. 2014, Japanese, 広島大学 東広島キャンパス, Domestic conference金属ジチオレンアニオンを含有する鉄（Ⅱ）スピンクロスオーバー錯体の構造と物性
Oral presentation
- 第８回分子科学討論会2014, Sep. 2014, Japanese, 広島大学 東広島キャンパス, Domestic conferenceプロンドナー性配位子を用いた鉄（Ⅱ）錯体の構造と物性
Poster presentation
- The 14th International Conference on Molecule-based Magnets, Jul. 2014, English, St. Petersburg, International conferenceUnusual magntetic behaviors of spin-crossover related mononuclear iron compounds
Poster presentation
- 日本化学会第94春季年会, Mar. 2014, Japanese, 名古屋, Domestic conference新規プロトン性配位子とその金属錯体の合成と性質
Poster presentation
- 日本化学会第94春季年会, Mar. 2014, Japanese, 名古屋, Domestic conference新規スピンクロスオーバーアニオンからなる複合機能性錯体の合成と性質
Oral presentation
- 日本化学会第94春季年会, Mar. 2014, Japanese, 名古屋, Domestic conference磁性アニオンを有する鉄(II)スピンクロスオーバー錯体の構造と物性
Oral presentation
- 日本化学会第94春季年会, Mar. 2014, Japanese, 名古屋, Domestic conferenceハロゲン結合相互作用を導入したスピンクロスオーバー伝導体の特異な構造転移
Oral presentation
- 神戸大学研究基盤センター「若手フロンティア研究会2013」, Dec. 2013, Japanese, 神戸, Domestic conferenceスピンクロスオーバーを示す新規アニオン性鉄(III)錯体の構造と物性
Poster presentation
- 錯体化学会第63回討論会, Nov. 2013, Japanese, 沖縄, Domestic conference新規な鉄(III)錯アニオンからなるスピンクロスオーバー錯体の構造と物性
Poster presentation
- 錯体化学会第63回討論会, Nov. 2013, Japanese, 沖縄, Domestic conferenceハロゲン結合を導入した複合機能性錯体の構造と物性
Oral presentation
- 分子研研究会「光による分子性伝導体の電子相制御」, Oct. 2013, Japanese, 岡崎, Domestic conferenceスピンクロスオーバー伝導体とその関連物質の外場応答
[Invited]
Invited oral presentation
- 第7回分子科学討論会, Sep. 2013, Japanese, 京都, Domestic conference新規アニオン性スピンクロスオーバー錯体の構造と物性
Poster presentation
- 第7回分子科学討論会, Sep. 2013, Japanese, 京都, Domestic conferenceカチオン–アニオン間相互作用を導入したスピンクロスオーバー複合機能性錯体の構造と物性
Oral presentation
- 日本化学会第93春季年会, Mar. 2013, Japanese, 草津, Domestic conference単核金属錯体を基盤とした多核金属錯体の合成と性質
Oral presentation
- 日本化学会第93春季年会, Mar. 2013, Japanese, 草津, Domestic conferenceハロゲン結合を導入した複合機能性スピンクロスオーバー錯体の構造と物性
Oral presentation
- 新学術領域研究「分子自由度が拓く新物質科学」第 7 回領域会議, Mar. 2013, Japanese, 東京, Domestic conferenceカチオン―アニオン間分子間相互作用による協同的スピン転移と磁性スイッチング
Nominated symposium
- 日本化学会第93春季年会, Mar. 2013, Japanese, 滋賀, Domestic conferenceCu(TCNQ)のヨウ素吸蔵能の評価
Oral presentation
- 九州大学先導物質化学研究所「先導研セミナー」, Feb. 2013, Japanese, 福岡, Domestic conference分子間相互作用に着目した双安定物質の開発と物性評価
Public discourse
- 兵庫県立大学大学院物質理学研究科フロンティア機能物質創製センターシンポジウム New materials Science from Hyogo, Dec. 2012, Japanese, 姫路, Domestic conference単核錯体を出発物質とした多核錯体の合成と物性
Poster presentation
- 神戸大学研究基盤センター「若手フロンティア研究会2012」, Dec. 2012, Japanese, 神戸, Domestic conference単核金属錯体配位子を基盤とした多核金属錯体の合成と性質
Poster presentation
- 兵庫県立大学大学院物質理学研究科フロンティア機能物質創製センターシンポジウム New materials Science from Hyogo, Dec. 2012, Japanese, 姫路, Domestic conferenceスピンクロスオーバーによる電気伝導性制御
Oral presentation
- 兵庫県立大学大学院物質理学研究科フロンティア機能物質創製センターシンポジウム New materials Science from Hyogo, Dec. 2012, Japanese, 姫路, Domestic conferenceカチオンーアニオン間相互作用を導入した複合機能性スピンクロスオーバー錯体の構造と物性
Poster presentation
- International Symposium on Materials Science Opened by Molecular Degrees of Freedom (MDF2012), Dec. 2012, English, Miyazaki, International conferencePressure and Photo Responses of Spin Crossover Related Compounds
Poster presentation
- 第22回(平成24年度)日本赤外線学会研究発表会, Nov. 2012, Japanese, 日本赤外線学会, Domestic conference非磁性不純物置換したS=1/2 ２本鎖スピン梯子物質(pipdH)2(Cu1-xZnx)Br4のテラヘルツESR測定
Poster presentation
- 日本化学会第92春季年会, Mar. 2012, Japanese, 日本生化学会, 横浜, Domestic conference鉄チオラート錯体からなるサーモクロミックイオン液体の開発
Oral presentation
- 日本化学会第92春季年会, Mar. 2012, Japanese, 日本生化学会, 横浜, Domestic conference固相反応によるTCNQ系電荷移動塩の合成と物性評価
Oral presentation
- 日本化学会第92春季年会, Mar. 2012, Japanese, 横浜, Domestic conference局在スピンを有する単核鉄錯体の構造と磁性
Oral presentation
- 熊本大学プロジェクトゼミナール, Mar. 2012, Japanese, 熊本, Domestic conference外場応答型分子性伝導体の開発
[Invited]
Invited oral presentation
- MDF International Mini-Workshop: Development of Molecular Degree of Freedom towards Novel Functionality, Nov. 2011, English, Kobe, Japan, International conferenceUnusual Magnetic Behavior of a Mononuclear Fe(III) Complex with a Phthalocyanione Anion
Oral presentation
- MDF International mini-Workshop "Development of Molecular Degree of Freedom towards Novel Functionality", Nov. 2011, English, International conferenceReversible Iodine Absorption of Alkali-TCNQ Salts Accompanying Drastic Changes of Physical Properties
Poster presentation
- MDF International Workshop: Open-shell Organic Molecules-Synthesis and Electronic Structure Freedom-, Oct. 2011, Japanese, Osaka, Japan, International conferenceDevelopment of Multifunctional Molecular Solids Coupled to a Spin Crossover Conversion
[Invited]
Invited oral presentation
- International Conference on the Applications of the Mössbauer Effect, Sep. 2011, English, Kobe, Japan, International conferenceMagnetic Splitting of Mössbauer Spectra in the Mononuclear Fe(III) Complex with a Phthalocyanine Anion
Oral presentation
Association Memberships
Japan Society of Molecular Science
The Society of Synthetic Organic Chemistry
The Physical Society of Japan
The Chemical Society of Japan
Research Projects
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Kobe University, 01 Apr. 2019 - 31 Mar. 2022機能性金属錯体における分子間相互作用の役割とその応用
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Kobe University, 01 Apr. 2014 - 31 Mar. 2017
Molybdenum blue bronze (MBB) is a CDW (charge density wave) material and its nanosized particles are expected to exhibit good photo-response and ballistic electron conduction. We revealed the formation mechanism of MBB nanoribbons and succeeded in finding out suitable conditions of their single-phase or nearly single-phase preparations. Furthermore, we succeeded in preparing various kinds of partially reduced alpha-MoO3 nanoribbons, the formation of which was found in this research program, and revealed they exhibit interesting properties for various gas detections.
Competitive research funding
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Kobe University, 01 Apr. 2013 - 31 Mar. 2017, Principal investigator
Spin crossover (SCO) complexes have attracted much attention as one of molecular switching materials induced by temperature, pressure, and light. In order to introduce intermolecular interactions between a cation and anion, multifunctional SCO compounds from the SCO cation and magnetic anion with halogen-bonding interactions were developed. The structural and magnetic characterizations revealed that it was successful to control a paramagnetic-nonmagnetic transformation of the magnetic anion by SCO. We also discovered completely novel SCO compounds featuring N2O4 and N3O3 donor atom sets which have never been reported. The systematic studies revealed that not isotropic interactions such as Coulomb and dispersion interactions but anisotropic intermolecular interactions such as π-π interactions played a crucial role in the SCO cooperativity which reflects the correlation between the spin-states of the neighboring SCO molecules.
Competitive research funding
- 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), Kobe University, 01 Apr. 2012 - 31 Mar. 2016
Functional metal-containing ionic liquids were synthesized from various cationic metal complexes. First, ionic liquids exhibiting vapochromic, magnetic, and other properties were developed from chelate complexes. Second, a series of ionic liquids were synthesized from metallocenium complexes, and their physical properties and chemical reactivities investigated. Correlations between the crystal structures and thermal properties of metallocenium salts were also investigated.
Competitive research funding
- 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), The University of Tokyo, 13 Nov. 2008 - 31 Mar. 2013
As the results in the aim for novel electronic functionalities by controlling intermolecular interaction, (1) novel molecular superconductors competitive with charge-ordered states were developed, (2) the theoretical analysis of the obtained superconductor proposed the symmetry of superconductivity. (3) Novel magnetic conductors and spin crossover complexes were developed by coordination of functional redox molecules to paramagnetic metals. (4) Novel purely organic single-component conductors and quantum spin liquid crystals were developed by coupling hydrogen-bonded protons and itinerant electrons.
- 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), The University of Tokyo, 2008 - 2011
The response of electric field has been investigated for the molecular conductorυ-(meso-DMeET) 2PF6, which is in the peculiar electronic state of both checkerboard-type charge ordering and dimer-Mott at low temperatures. The titled crystal shows the large nonlinear conduction and the electric-field induced metastable state. This response is quick in proportional to(electric field)^3. The measurement of raman spectroscopy synchronized to the pulsed electric field suggests the melting of the charge ordering in the metastable state with the intermediate resistivity.
- 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), The University of Tokyo, 2007 - 2008
温度・圧力・光・電場などの外場に応答する新しい分子性物質を開発するために、双安定分子であるスピンクロスオーバー分子を分子性伝導体や分子性誘電体へ導入することにより、スピンクロスオーバーと伝導性・誘電性のカップルしたスピンクロスオーバー伝導体や誘電体の開発に成功した。そのカップリングのメカニズムの検討からスピンクロスオーバー分子間に働く強い分子間相互作用が複合機能性を実現するための重要なポイントであることを明らかにした。
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Priority Areas, Grant-in-Aid for Scientific Research on Priority Areas, The University of Tokyo, 2006 - 2007新奇磁性分子性導体の開発
磁性分子性導体の多くはπ電子ドナーと遷移金属磁性アニオンからなる伝導体であり、伝導電子と局在スピンとの間の磁気的相互作用は結晶構造に大きく依存しているため、π電子ドナー分子の設計からその磁気的相互作用を予測することができないのが現状である。そこで(1)π電子ドナーに安定有機ラジカルを結合させることにより、分子内での磁気的相互作用が期待される磁性分子性導体の開発(2)局在スピンとして鉄スピンクロスオーバーイオンを有する外場応答型磁性分子性導体の開発という二通りのアプローチで新奇磁性伝導体の開発を行ってきた。本年度は(1)昨年度開発した安定有機ラジカルPROXYL縮環π電子ドナーPROXYL-STFのπ共役系を拡張したPROXYL-DS-TTP誘導体の合成とキャラクタリゼーションに成功した。電解酸化により得られたカチオンラジカル塩(PROXYL-DS-TTP)BF_4・PhCIの結晶構造解析からPROXYLラジカルの存在が示唆され、この系において今後安定有機ラジカルを有するドナーからなる分子性金属への展開が期待される。(2)昨年度報告した光応答型スピンクロスオーバー伝導体[Fe^
(qsal)_2][Ni(dmit)_2]_3-CH_3CN-H_2Oの類縁体[Fe^ (qnal)_2][Pd(dmit)_2]_5-acetoneがM(dmit)_2錯体として二例目となるスピンクロスオーバー伝導体であり、その低温相と高温相の結晶構造解析からスピンクロスオーバーによるカチオンの構造変化ばかりではなく、スピンクロスオーバーカチオン間の強い分子間相互作用による協同的な一軸格子変調が伝導性の変化を誘起しているというメカニズムを明らかにすることができた。このような分子間相互作用による協同効果が双安定状態の実現に対して重要であり、今後伝導性以外の電子物性制御への展開が期待される結果である。 - Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), The University of Tokyo, 2005 - 2007Research of Competition and Coexistence of Charge-ordered and Superconducting States in Novel Organic Superconductors
In order to investigate the relationship between charge ordering and superconductivity for novel organic superconductor beta-(meso-DMBEDT-TTF)_2PF_6, the detailed measurements of electrical resistivity and magnetoresistivity have been carried out. Our results are followings. (1) Determination of superconducting state by measurements of electrical and magnetoresistivity under pressureThe detailed measurements of electrical resistivity under pressure revealed that the resistance drop of observed at Tc(onset) = 4.6 K under relatively low pressure 0.6 kbar, whose superconductivity was confirmed by applying magnetic field. The superconducting phase extends widely to Tc=2.6K under 5.2 kbar. (2) Determination of charge-ordered state by temperature and magnetic field dependences of magnetoresistance under pressure The temperature dependence of resistivity for beta-(meso-DMBEDT-TTF)_2PF_6 is peculiar under 0.6 kbar; the resistivity minimum is observed at 60K, the increase of resistivity by 8 times with lowering temperature, and the sudden drop of resitivity is observed at 4.6K. The raman spectroscopy under pressure demonstrates that the resistivity increase is originated by charge ordering (CO). In this CO region, large magnetoresistance was observed, its increasing rate (ΔR/R(0T)) increases with applying pressure, and in even the metallic state at low temperatures, the magnetoresistance can be observed. Therefore, the illustrated P-T phase diagram reveals that the static and dyanimical CO states exist in neighbouring of superconducting state, which is the first experimental observation among molecular superconductors.
- ＪＳＴ戦略的創造研究推進制度（研究チーム型） （戦略的基礎研究推進事業：ＣＲＥＳＴ）, 2003 - 2007分子機能性材料
Competitive research funding
- JST Basic Research Programs (Core Research for Evolutional Science and Technology :CREST), 2003 - 2007Molecular-based Functional Materials
Competitive research funding
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows, Grant-in-Aid for JSPS Fellows, Kyoto University, 1999 - 2000分子性導体におけるカルコゲン原子間相互作用の結晶構造制御への応用