2024/03/26 更新

写真a

スイヅ リエ
水津 理恵
SUIZU Rie
所属
大学院理学研究科 理学専攻 化学 特任助教
職名
特任助教
外部リンク

学位 1

  1. 博士(理学) ( 2001年3月   東北大学 ) 

受賞 1

  1. 黒田チカ賞

    1999年3月   青葉理学振興会  

    塩沢 理恵

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論文 43

  1. Optoelectronic conversion and polarization hysteresis in organic MISM and MISIM devices with DA-type single-component molecules 招待有り 査読有り 国際誌

    Tomimatsu, A; Suizu, R; Nakazawa, M; Shirahata, T; Misaki, Y; Kinoshita, N; Awaga, K

    FARADAY DISCUSSIONS   250 巻 ( 0 ) 頁: 96 - 109   2024年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Faraday Discussions  

    Organic electronic devices offer various advantages, such as low cost and tunability. However, the organic semiconductors used in these devices have significant drawbacks, including instability in air and low carrier mobility. To address these challenges, we recently introduced organic MISM and MISIM (M = metal, I = insulator, S = semiconductor) devices, which effectively generate photo-induced displacement current and exhibit ferroelectric behavior. In previous studies, the S layer consisted of an organic donor-acceptor (DA) bilayer. In the present research, we fabricated MISM and MISIM devices using DA-type single-component molecules as the S layer and examined their photocurrent and polarization hysteresis. While the performance of these devices does not surpass that of DA bilayer devices, we discovered that DA-type single-component molecules can be utilized for photoelectric conversion and polarization trapping.

    DOI: 10.1039/d3fd00125c

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  2. グラフ理論で解き明かす分子性強等方性構造の電子物性

    水津 理恵

    日本結晶学会誌   66 巻 ( 1 ) 頁: 31 - 38   2024年2月

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    記述言語:日本語   出版者・発行元:日本結晶学会  

    DOI: 10.5940/jcrsj.66.31

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  3. Critical transition to a highly conductive state through PEDOT oligomer percolation in redox-active COFs

    Cao, CQ; Chen, Q; Suizu, R; Awaga, K

    JOURNAL OF MATERIALS CHEMISTRY C   12 巻 ( 9 ) 頁: 3072 - 3076   2024年2月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Materials Chemistry C  

    Covalent organic frameworks (COFs) have garnered significant attention in recent years, but they generally suffer from low electrical conductivity. In our previous studies, we observed that the nano-hybrid material PEDOT@AQ-COF (PEDOT = poly(3,4-ethylenedioxythiophene) and AQ-COF = ketoenamine-linked COF with anthraquinone (AQ) moieties), formed by polymerizing the organic conductive polymer PEDOT within the hollow pores of a COF, demonstrates outstanding electrical conductivity and energy storage properties. In this study, we systematically synthesized samples with various ratios of PEDOT to AQ-COF by adjusting the concentration of the precursor molecule in AQ-COF. Elemental analysis results indicated that PEDOT exists as oligomers with a degree of polymerization between 3.4 and 5.6, and there is a saturation point for the amount of PEDOT. This saturation state suggests that the PEDOT chains are densely packed within the cavity of AQ-COF, forming molecular contacts between PEDOT and AQ-COF. We assessed the electrical conductivity, electrochemical properties, and electron paramagnetic resonance (EPR) of the PEDOT@AQ-COF series. We observed that, upon reaching the saturation point of PEDOT, a critical transition occurs to a highly conductive state. In this state, the cyclic voltammetry curves exhibit redox reactions of AQ-COF, assisted by the PEDOT guest molecules. Compared to the low-conductivity sample, the high-conductivity samples in EPR displayed a broader linewidth component with nearly temperature-independent spin susceptibility.

    DOI: 10.1039/d3tc04794f

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  4. Synthesis of a novel triptycene-derived protected dithiolene ligand precursor for tri-nuclear mixed ligand metal dithiolene complexes

    Wang A., Shuku Y., Suizu R., Robertson N., Awaga K.

    Chemistry Letters   53 巻 ( 2 )   2024年2月

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    出版者・発行元:Chemistry Letters  

    We synthesized a novel triptycene analogue, 3,3′,3″,3″′,3″″,3″″′-((triptycene-2,3,6,7,14,15-hexayl)hexakis(sulfanediyl))hexapropanenitrile (3), which served as a valuable precursor for the triptycene-derived tris-bidentate bridging dithiolene ligand, triptycene-2,3,6,7,14, 15-hexakis(thiolate) (4), following the removal of the cyanoethyl moiety protection group. We determined the molecular and crystal structures of compound 3 and confirmed its capacity to yield compound 4. By reacting 3 with [NiCl2(BPY)] and [PtCl2(BPY)] (BPY: 2,2′-bipyridine) in methanol, we obtained crude samples of [Ni3(4)(BPY)3] and [Pt3(4)(BPY)3], respectively.

    DOI: 10.1093/chemle/upad051

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  5. X-ray crystallographic analysis of the antiferromagnetic low-temperature phase of galvinoxyl: investigating magnetic duality in organic radicals

    Suizu, R; Shuku, Y; Robert, V; Roseiro, P; Ben Amor, N; Khawar, Z; Robertson, N; Awaga, K

    DALTON TRANSACTIONS   53 巻 ( 5 ) 頁: 1961 - 1965   2024年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Dalton Transactions  

    Galvinoxyl, as one of the most extensively studied organic stable free radicals, exhibits a notable phase transition from a high-temperature (HT) phase with a ferromagnetic (FM) intermolecular interaction to a low-temperature (LT) phase with an antiferromagnetic (AFM) coupling at 85 K. Despite significant research efforts, the crystal structure of the AFM LT phase has remained elusive. This study successfully elucidates the crystal structure of the LT phase, which belongs to the P1̄ space group. The crystal structure of the LT phase is found to consist of a distorted dimer, wherein the distortion arises from the formation of short intermolecular distances between anti-node carbons in the singly-occupied molecular orbital (SOMO). Starting from the structure of the LT phase, wave function calculations show that the AFM coupling 2J/kB varies significantly from −1069 K to −54 K due to a parallel shift of the molecular planes within the dimer.

    DOI: 10.1039/d3dt03601d

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  6. Ideal trigonal prismatic coordination geometry of Co(ii) in a honeycomb MOF with a triptycene-based ligand

    Shuku, Y; Suizu, R; Tsuchiizu, M; Awaga, K

    CHEMICAL COMMUNICATIONS   59 巻 ( 67 ) 頁: 10105 - 10108   2023年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemical Communications  

    A metal-organic framework (MOF) comprised of cobalt ions and triptycene-based 3-fold symmetric bridging ligands 9,10-[1,2]benzenoanthracene-2,3,6,7,14,15(9H,10H)-hexaone (o-TT) was prepared. Single-crystal structure analysis revealed a 2D honeycomb network structure and the ideal trigonal prismatic geometry of the Co(ii) ion. The magnetic anisotropy of the Co(ii) ion in the trigonal prism coordination geometry was analyzed via magnetic measurements and model calculations.

    DOI: 10.1039/d3cc02986g

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  7. Engineering Dirac cones and topological flat bands with organic molecules 査読有り

    Shuku, Y; Suizu, R; Nakano, S; Tsuchiizu, M; Awaga, K

    PHYSICAL REVIEW B   107 巻 ( 15 )   2023年4月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Physical Review B  

    We investigated polyhedral π-conjugated molecules with threefold rotation symmetry, which can be suitable building blocks for both Dirac cones and a topological flat-band system. The two dimensional network structures of such molecules can be characterized by intra- and intermolecular interactions. We constructed tight binding models of these structures by systematically changing the intra- (t0) and intermolecular (t1) transfer integrals as independent parameters. The degree of freedom for the interactions provides a topological flat band and a massless or massive Dirac cone. We analyzed the topological features and origins of the flat band and Dirac cone of a molecule-based triangular lattice.

    DOI: 10.1103/PhysRevB.107.155123

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    その他リンク: http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.107.155123/fulltext

  8. Enhanced Circularly Polarized Luminescence by a Homochiral Guest-Host Interaction in Gyroidal MOFs, [Ru(bpy)<sub>3</sub>] [M<sub>2</sub>(ox)<sub>3</sub>] (bpy = 2,2'-Bipyridyl, ox = Oxalate, M = Zn, Mn) 査読有り

    Nakashima, K; Suizu, R; Morishita, S; Tsurumachi, N; Funahashi, M; Masu, H; Ozawa, R; Nakamura, K; Awaga, K

    ACS MATERIALS AU   3 巻 ( 3 ) 頁: 201 - 205   2023年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Materials Au  

    We report the circularly polarized luminescence (CPL) for [Ru(bpy)3]I2 (1) and [Ru(bpy)3][M2(ox)3] (M = Zn (2), Mn (3)). Whereas compound 1 is a simple salt of [Ru(bpy)3]2+, 2 and 3 are MOFs in which the chiral [Ru(bpy)3]2+ ions are encapsulated in a homochiral gyroidal skeleton of [M2(ox)3]2-. Whereas the solution of 1 exhibited weak CPL with a luminescence dissymmetry factor of |glum| ∼ 10-4, the CPL was significantly enhanced in solid-state 1-3 with |glum| = 2 × 10-2 for 1, 4 × 10-2 for 2, and 1 × 10-1 for 3. The enhanced CPL in 3 was attributable to an energy transfer between the homochiral guest and host in 3.

    DOI: 10.1021/acsmaterialsau.2c00081

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  9. Fabrication of MXene transparent conductive films via transfer process 査読有り

    Shibata, Y; Suizu, R; Awaga, K; Hirotani, J; Omachi, H

    APPLIED PHYSICS EXPRESS   16 巻 ( 3 )   2023年3月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied Physics Express  

    In this study, we fabricate MXene transparent conductive films via a transfer process. The results show that the transferred transparent conductive films using titanium carbide MXene have ca. 100 times higher electrical conductivity than conventional spray-coated samples. Transparency and electrical conductivity are easily controlled by changing the amount of MXene materials. The scanning electron microscopy observations reveal that the transferred films have a smooth and uniform MXene flake network. The closer interlayer distance of the MXene flakes when compared to the spray-coated sample, which enables superior electrical conductivity, is confirmed by the X-ray diffraction measurement.

    DOI: 10.35848/1882-0786/acbbb8

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  10. CNT Gels Formed by a Triptycene Analogue Enabling Coexistence of CNT-gelator and Intergelator Interactions 査読有り

    Ushiroguchi, R; Suizu, R; Matsunaga, Y; Omachi, H; Doi, Y; Masubuchi, Y; Bandow, S; Awaga, K

    CHEMISTRY LETTERS   51 巻 ( 11 ) 頁: 1070 - 1073   2022年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemistry Letters  

    We report carbon nanotube (CNT) gels, formed by mechanically mixing CNTs, organic solvents, and a small molecule, Trip-Phz, that have a strong affinity for fullerene materials. There is a clear threshold value in the amount of Trip-Phz needed for the transition from soft to hard gels.

    DOI: 10.1246/cl.220319

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  11. N-doped nonalternant aromatic belt via a six-fold annulative double N-arylation

    Sato Hiroki, Suizu Rie, Kato Tomoki, Yagi Akiko, Segawa Yasutomo, Awaga Kunio, Itami Kenichiro

    CHEMICAL SCIENCE   13 巻 ( 34 ) 頁: 9947 - 9951   2022年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemical Science  

    The design and synthesis of nitrogen (N)-doped molecular nanocarbons are of importance since N-doped nanocarbons have received significant attention in materials science. Herein, we report the synthesis and X-ray crystal structure of a nitrogen-inserted nonalternant aromatic belt. The palladium-catalyzed six-fold annulative double N-arylation provided an aromatic belt bearing six nitrogen atoms in one step from cyclo[6]paraphenylene-Z-ethenylene, the precursor of the (6,6)carbon nanobelt. The C3i-symmetric structure of the aromatic belt in the solid state was revealed using X-ray crystallography. The multistep (electro)chemical oxidation behavior of the belt, which was facilitated by the six p-methoxyaniline moieties, was studied, and a stable dication species was successfully identified by X-ray crystallography. The present study not only shows the unique structure and properties of the N-doped nonalternant aromatic belt but also expands the scope of accessibility of synthetically difficult belt molecules by the conventional intramolecular contraction pathway.

    DOI: 10.1039/d2sc02647c

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  12. Improvement in Cycle Life of Organic Lithium-Ion Batteries by In-Cell Polymerization of Tetrathiafulvalene-Based Electrode Materials

    Yoshimura, A; Hemmi, K; Moriwaki, H; Sakakibara, R; Kimura, H; Aso, Y; Kinoshita, N; Suizu, R; Shirahata, T; Yao, MSR; Yorimitsu, H; Awaga, K; Misaki, Y

    ACS APPLIED MATERIALS & INTERFACES   14 巻 ( 31 ) 頁: 35978 - 35984   2022年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Applied Materials and Interfaces  

    Redox-active organic molecules are promising candidates for next-generation electrode materials. Nevertheless, finding low-molecular-weight organic materials with a long cycle life remains a crucial challenge. Herein, we demonstrate the application of tetrathiafulvalene and its vinyl analogue bearing triphenylamines as long-cycle-life electrodes for lithium-ion batteries (LIBs). These molecules were successfully synthesized using palladium-catalyzed C-H arylation. Electrochemical analysis revealed that a polymer formed on the electrode. LIBs comprising these molecules exhibited noteworthy charge-discharge properties with a long cycle life (the capacity after 100 cycles was greater than 90% of the discharge capacity in the third cycle) and a high utilization ratio (approximately 100%). "In-cell"polymerization during the first charge process is considered to contribute to the effect. This study indicates new avenues for the creation of organic materials for rechargeable batteries.

    DOI: 10.1021/acsami.2c09302

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  13. Exfoliation of Al-Residual Multilayer MXene Using Tetramethylammonium Bases for Conductive Film Applications 査読有り 国際誌

    Saita, E; Iwata, M; Shibata, Y; Matsunaga, Y; Suizu, R; Awaga, K; Hirotani, J; Omachi, H

    FRONTIERS IN CHEMISTRY   10 巻   頁: 841313 - 841313   2022年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Frontiers in Chemistry  

    This study describes the concise exfoliation of multilayer Ti3C2Tx MXene containing residual aluminum atoms. Treatment with tetramethylammonium base in a co-solvent of tetrahydrofuran and H2O produced single-layer Ti3C2Tx, which was confirmed via atomic force microscopy observations, with an electrical conductivity 100+ times that of Ti3C2Tx prepared under previously reported conditions. The scanning electron microscopy and X-ray diffraction measurements showed that the exfoliated single-layer Ti3C2Tx MXenes were reconstructed to assembled large-domain layered films, enabling excellent macroscale electric conductivity. X-ray photoelectron spectroscopy confirmed the complete removal of residual Al atoms and the replacement of surface fluorine atoms with hydroxy groups. Using the exfoliated dispersion, a flexible transparent conductive film was formed and demonstrated in an electrical application.

    DOI: 10.3389/fchem.2022.841313

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  14. Line graph theory reveals hidden spin frustration and bond frustration in molecular crystals with strong isotropy 査読有り

    Suizu, R; Awaga, K

    JOURNAL OF MATERIALS CHEMISTRY C   10 巻 ( 4 ) 頁: 1196 - 1203   2022年1月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Materials Chemistry C  

    Graph theory has demonstrated that only three lattices, namely, honeycomb, K4, and diamond lattices, possess a strong isotropic property. It is also recognized that their line graphs correspond to kagome, hyper-kagome, and pyrochlore lattices, respectively, which are well known as spin frustration lattices. This relation suggests that the materials with the strong isotropic lattices possess "hidden"frustration. In this review article, after introducing the strong isotropy and the line graph transformation, we describe the spin frustration and formation of the spin liquid state in a honeycomb MOF, Cu3(HHTP), and in a molecule-based K4, (-)-NDI-Δ. We also report the unusual phase transitions in a molecule-based diamond, bpBDTDA, which are considered to result from bond frustration: specific periodical lattice distortions in the strong isotropic lattices are forbidden, in such a way that long-range antiferromagnetic orderings are forbidden in the spin frustration lattices.

    DOI: 10.1039/d1tc05161j

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  15. 3D supramolecular chiral crystal structures of radical anion salts of (-)-NDI-Delta and possible magnetic phase diagrams 査読有り

    Mizuno Asato, Shuku Yoshiaki, Suizu Rie, Tsuchiizu Masahisa, Awaga Kunio

    CRYSTENGCOMM   23 巻 ( 29 ) 頁: 5053 - 5059   2021年8月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CrystEngComm  

    Supramolecular chiral crystals of radical anion salts of a rigid triangular chiral electron acceptor, (−)-naphthalene diimide (NDI)-Δ, were electrochemically grown in propylene carbonate (PC) solutions of electrolytes (M·ClO4, M = K, Rb, Cs) in the presence of cyclic multidentate ligands, such as 18-crown-6, 15-crown-5, and 2,2,2-cryptand. The crystal structures were found to be formed by three-way branched π-π interactions between (−)-NDI-Δ radical anions, including [Rb(or K)(18-crown-6)]+complexes. The theoretical calculations on this structure revealed a possible magnetic phase diagram, which was governed by the ratio between two types of antiferromagnetic interactions.

    DOI: 10.1039/d1ce00628b

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  16. Stabilization of Interfacial Polarization and Induction of Polarization Hysteresis in Organic MISIM Devices 査読有り

    Yokokura, S; Tomimatsu, A; Ishiguro, J; Harada, J; Takahashi, H; Takahashi, Y; Nakamura, Y; Kishida, H; Suizu, R; Matsushita, MM; Awaga, K

    ACS APPLIED MATERIALS & INTERFACES   13 巻 ( 27 ) 頁: 31928 - 31933   2021年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Applied Materials and Interfaces  

    Molecule-based ferroelectrics has attracted much attention because of its advantages, such as flexibility, light weight, and low environmental load. In the present work, we examined an organic metal|insulator|semiconductor|insulator|metal (MISIM) device structure to stabilize the interfacial polarization in the S layer and to induce polarization hysteresis even without bulk ferroelectrics. The MISIM devices with I = parylene C and S = TMB (=3,3′,5,5′-tetramethylbenzidine)-TCNQ (=tetracyanoquinodimethane) exhibited hysteresis loops in the polarization-voltage (P-V) curves not only at room temperature but also over a wide temperature range down to 80 K. The presence of polarization hysteresis for MISIM devices was theoretically confirmed by an electrostatic model, which also explained the observed thickness dependence of the I layers on the P-V curves. Polarization hysteresis curves were also obtained in MISIM devices using typical organic semiconductors (ZnPc, C60, and TCNQ) as the S layer, demonstrating the versatility of the interfacial polarization mechanism.

    DOI: 10.1021/acsami.1c08417

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  17. Oxidative vaporization etching for molybdenum tip formation in air 査読有り

    Goto, Y; Suizu, R; Noguchi, Y; Yamada, TK

    APPLIED SURFACE SCIENCE   542 巻   頁: 148642 - 148642   2021年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied Surface Science  

    Oxidative vaporization in air using a flame with a temperature range of 1950–2300 K was employed for controlling the tip shape made from a nipper-cut metal molybdenum (Mo) wire edge. An extremely high vapor pressure of MoO3 generated on the Mo surface in flame is a driving force behind the tip shape formation. Since the MoO3 vaporization rate follows the flame temperature gradient, we could control the tip apex shape by selecting the proper flame etching condition. The best condition to obtain a sharp tip apex based on statistical tests of dozens of Mo tips was obtained by Mo wire edge insertion into the 2100 K flame from the side for one second. This was repeated twice, which reproducibly provided a tip apex with a radius of 50–100 nm and a cone angle of 20–30 degrees. The present Mo tips, fabricated without aqueous solutions, were examined for their suitability as probe tips through air-scanning tunneling microscopy (STM), ultrahigh vacuum STM, field emission spectroscopy, and conductance measurements.

    DOI: 10.1016/j.apsusc.2020.148642

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  18. Variable Host-Guest Charge-Transfer Interactions in 1D Channels Formed in a Molecule-Based Honeycomb Lattice of Phenazine Analogue of Triptycene 査読有り

    Ushiroguchi, R; Shuku, Y; Suizu, R; Awaga, K

    CRYSTAL GROWTH & DESIGN   20 巻 ( 12 ) 頁: 7593 - 7597   2020年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Crystal Growth and Design  

    We synthesized a phenazine analogue of triptycene acceptor, Trip-Phz, and found a honeycomb network of Trip-Phz with a wide 1D channel running through it. The interior surface of this channel was covered by the πelectrons of Trip-Phz. Even though there was no interaction between Trip-Phz and an organic donor, tetrathiafulvalene (TTF), in their solutions, the honeycomb crystals of Trip-Phz exhibited a host-guest charge-transfer (CT) interaction with TTF, specifically a reversible adsorption/desorption of TTF with the appearance/disappearance of a CT band.

    DOI: 10.1021/acs.cgd.0c01176

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  19. 分子性強等方性物質の合成とトポロジー物性の開拓 査読有り

    阿波賀邦夫, 水津理恵

    固体物理   55 巻 ( 9 ) 頁: 409 - 423   2020年9月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

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  20. ライングラフが解き明かす分子性K4およびDiamond格子の隠されたフラストレーション 査読有り

    水津理恵, 阿波賀邦夫

    Molecular Science   14 巻 ( 1 ) 頁: A0113 - A0113   2020年

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    担当区分:筆頭著者   記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:分子科学会  

    <p>In the graph theory, it is known that the line graphs of the <i>K</i><sub>4</sub> and diamond lattices are the hyper-kagome and pyrochlore lattices, respectively. The hyper-kagome and pyrochlore lattices are possible frustration lattices, because they consist of a triangular or tetrahedral component. In the present article, we describe the crystal structures and physical properties of a molecule-based <i>K</i><sub>4</sub>, (–)-NDI-Δ, and a molecule-based diamond, bpBDTDA. The line graph transformation reveals a spin frustration in (–)-NDI-Δ, which results in a spin liquid ground state, and a bond frustrations in bpBDTDA, which induces a stepwise and inhomogeneous lattice dimerization.</p>

    DOI: 10.3175/molsci.14.a0113

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  21. Self-assembled honeycomb lattice in the monolayer of cyclic thiazyl diradical BDTDA (=4,4 '-bis(1,2,3,5-dithiadiazolyl)) on Cu(111) with a zero-bias tunneling spectra anomaly 査読有り

    Yamamoto Masayuki, Suizu Rie, Dutta Sudipta, Mishra Puneet, Nakayama Tomonobu, Sakamoto Kazuyuki, Wakabayashi Katsunori, Uchihashi Takashi, Awaga Kunio

    SCIENTIFIC REPORTS   5 巻   頁: 18359   2015年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Scientific Reports  

    Scanning tunneling microscopy (STM) observation reveals that a cyclic thiazyl diradical, BDTDA (= 4,4′-bis(1,2,3,5-dithiadiazolyl)), forms a well-ordered monolayer honeycomb lattice consisting of paramagnetic corners with unpaired electrons on a clean Cu(111) surface. This BDTDA lattice is commensurate with the triangular lattice of Cu(111), with the former being 3 x 3 larger than the latter. The formation of the BDTDA monolayer structure, which is significantly different from its bulk form, is attributed to an interaction with the metal surface as well as the intermolecular assembling forces. STM spectroscopy measurements on the BDTDA molecules indicate the presence of a characteristic zero-bias anomaly centered at the Fermi energy. The origin of this zero-bias anomaly is discussed in terms of the Dirac cones inherent to the honeycomb structure.

    DOI: 10.1038/srep18359

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  22. Discovery of the K-4 Structure Formed by a Triangular pi Radical Anion 査読有り

    Mizuno Asato, Shuku Yoshiaki, Suizu Rie, Matsushita Michio M., Tsuchiizu Masahisa, Reta Maneru Daniel, Illas Francesc, Robert Vincent, Awaga Kunio

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   137 巻 ( 24 ) 頁: 7612 - 7615   2015年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of the American Chemical Society  

    The K4 structure was theoretically predicted for trivalent chemical species, such as sp2 carbon. However, since attempts to synthesize the K4 carbon have not succeeded, this allotrope has been regarded as a crystal form that might not exist in nature. In the present work, we carried out electrochemical crystallization of the radical anion salts of a triangular molecule, naphthalene diimide (NDI)-Δ, using various electrolytes. X-ray crystal analysis of the obtained crystals revealed the K4 structure, which was formed by the unique intermolecular π overlap directed toward three directions from the triangular-shape NDI-Δ radical anions. Electron paramagnetic resonance and static magnetic measurements confirmed the radical anion state of NDI-Δ and indicated an antiferromagnetic intermolecular interaction with the Weiss constant of θ = -10 K. The band structure calculation suggested characteristic features of the present material, such as a metallic ground state, Dirac cones, and flat bands.

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  23. Spatially inhomogeneous, stepwise phase transitions in a thiazyl diradical: a structural mismatch induced by lattice transformation 査読有り

    Suizu, R; Iwasaki, A; Shuku, Y; Awaga, K

    JOURNAL OF MATERIALS CHEMISTRY C   3 巻 ( 30 ) 頁: 7968 - 7977   2015年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Materials Chemistry C  

    A heterocyclic thiazyl diradical, bis(1,2,3,5-dithiadiazolyl)-4,4′-biphenylene (1), was synthesized, and its structural and thermodynamic properties were characterized. This compound exhibits unique spatially inhomogeneous, first-order phase transitions at 306 and 359 K, in a stepwise fashion. The unit cell in the high-temperature phase above 359 K consists of four regular π-stacking columns with the same stacking manners having a uniform interplanar distance d. These four columns are connected by intermolecular S⋯S and S⋯N contacts between the thiazyl radical moieties, but the molecular planes are shifted by a distance of d/4 due to a steric hindrance between the bulky biphenylene moieties. Below 359 K, three of the four stacking columns exhibit structural transitions toward zigzag chain structures, formed by an alternating dimerization between the radical moieties, while one column maintains the uniform π stacking. In the low-temperature phase below 306 K, the last column finally exhibits the radical dimerization toward a zigzag chain structure. These unique phase transitions in 1 can be understood in terms of the stepwise transitions from a "dimer liquid" to a "dimer solid" through a "dimer soliton phase".

    DOI: 10.1039/c5tc01410g

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  24. The key role of vibrational entropy in the phase transitions of dithiazolyl-based bistable magnetic materials 査読有り

    Vela, S; Mota, F; Deumal, M; Suizu, R; Shuku, Y; Mizuno, A; Awaga, K; Shiga, M; Novoa, JJ; Ribas-Arino, J

    NATURE COMMUNICATIONS   5 巻   頁: 4411   2014年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Nature Communications  

    The neutral radical 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) is a prototype of molecule-based bistable materials. TTTA crystals undergo a first-order phase transition between their low-temperature diamagnetic and high-temperature paramagnetic phases, with a large hysteresis loop that encompasses room temperature. Here, based on ab initio molecular dynamics simulations and new X-ray measurements, we uncover that the regular stacking motif of the high-temperature polymorph is the result of a fast intra-stack pair-exchange dynamics, whereby TTTA radicals continually exchange the adjacent TTTA neighbour (upper or lower) with which they form an eclipsed dimer. Such unique dynamics, observed in the paramagnetic phase within the whole hysteresis loop, is the origin of a significant vibrational entropic gain in the low-temperature to high-temperature transition and thereby it plays a key role in driving the phase transition. This finding provides a new key concept that needs to be explored for the rational design of novel molecule-based bistable magnetic materials. © 2014 Macmillan Publishers Limited.

    DOI: 10.1038/ncomms5411

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  25. Third-Order Nonlinear Optical Properties and Electroabsorption Spectra of an Organic Biradical, [Naphtho[2,1-d:6,5-d ']bis([1,2,3]dithiazole)] 査読有り

    Takauji Keigo, Suizu Rie, Awaga Kunio, Kishida Hideo, Nakamura Arao

    JOURNAL OF PHYSICAL CHEMISTRY C   118 巻 ( 8 ) 頁: 4303 - 4308   2014年2月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Physical Chemistry C  

    Thin films of a thiazyl biradical, naphtho[2,1-d:6,5-d′]bis([1,2,3] dithiazole), abbreviated as NT, exhibit nonlinear optical properties with a large third-order nonlinear susceptibility of 2.1 × 10-11 esu. The electroabsorption and low-temperature-absorption measurements reveal a series of degenerate electronic states, which is probably caused by the biradical character of NT. It is concluded that this degeneracy should enhance the third-order nonlinear optical properties. © 2014 American Chemical Society.

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  26. Electron-Transfer Processes in Highly-Correlated Electron Systems of Thiazyl Radicals 招待有り 査読有り

    Awaga, K; Nomura, K; Kishida, H; Fujita, W; Yoshikawa, H; Matsushita, MM; Hu, LG; Shuku, Y; Suizu, R

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   87 巻 ( 2 ) 頁: 234 - 249   2014年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Bulletin of the Chemical Society of Japan  

    Heterocyclic thiazyl radicals possess unique chemical and physical properties as building blocks for molecule-based conductors and magnetic materials. They do not need protecting groups on their molecular skeletons, and the lack of such substituents permits close packing in the solid state. Moreover, thiazyl radical solids often involve a multidimensional network consisting of π-π overlaps and S⋯N contacts. The electronic structures of the thiazyl radicals can be compared to highly-correlated electron systems. In this account, we describe various electron-transfer processes in the solids of the thiazyl radicals, which manifest themselves by external stimuli such as temperature change, electric field, and photoillumination. © 2013 The Chemical Society of Japan.

    DOI: 10.1246/bcsj.20130248

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  27. Multidimensional Network Structures and Versatile Magnetic Properties of Intermolecular Compounds of a Radical Anion Ligand, [1,2,5]Thiadiazolo[3,4-f][1,10]phenanthroline 1,1-Dioxide 査読有り

    Shuku, Y; Suizu, R; Domingo, A; Calzado, CJ; Robert, V; Awagat, K

    INORGANIC CHEMISTRY   52 巻 ( 17 ) 頁: 9921 - 9930   2013年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Inorganic Chemistry  

    The crystal structures and magnetic properties of seven kinds of [1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 1,1-dioxide (tdapO2) radical-anion salts, namely, K·tdapO2, K·tdapO 2·0.5MeCN, K·(tdapO2)2, Rb·(tdapO2)2, Cs7·(tdapO 2)6·ClO4, (NH4) 2·tdapO2·I, and Hppda·tdapO 2·MeCN, were investigated. Single-crystal X-ray analyses of these radical-anion salts revealed formation of π-stacking columns and the presence of intercolumnar coordination bonding or hydrogen bonding. The intermolecular magnetic coupling constants in these salts range from strong antiferromagnetic (J/kB = -310 K) to ferromagnetic (J/kB = 24 K). Ab initio calculations performed on the nearest-neighbor radical pairs in the π-stacking columns suggested that the magnetic interactions are strongly governed by the overlap between the two anionic radical species and well explain the observed ferromagnetic and antiferromagnetic interactions. In addition, calculations of a hypothetical oxygen-less tdap analogue suggested that the presence of oxygen in tdapO2 significantly reduces the hopping integral and enhances the probability of ferromagnetic interaction. © 2013 American Chemical Society.

    DOI: 10.1021/ic401078z

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  28. Electronic structure of organic biradical molecular films

    Kanai K., Koike H., Suizu R., Awaga K., Mase K., Kubo T.

    Journal of the Vacuum Society of Japan   56 巻 ( 1 ) 頁: 32 - 38   2013年3月

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    記述言語:日本語   出版者・発行元:Journal of the Vacuum Society of Japan  

    Most research in the fleld of organic electronics has focused on p-conjugated molecules with a closed-shell configuration, which accommodate their p-electrons in only bonding orbitals and are consequently quite stable. In general, closed-shell molecules have wide energy gaps, and they have significantly weaker intermolecular interactions. In contrast, recently organic biradicals have attracted considerable attention, owing to their interesting physical properties, e.g., a small energy gap and strong intermolecular interactions. Organic biradical molecules are composed of a pair of organic radicals that possess an open-shell configuration. Owing to their radical nature, biradical molecules exhibit unusual physical properties such as those listed above. This article is a review of our recent study on the electronic structure of two different types of organic biradical molecules that have potential as new materials for manufacturing electronic devices. In particular, our results show that organic biradicals are expected to form a new class of materials for use in organic electronics as new building blocks for highly ordered organic semiconducting films with wide energy band dispersion widths and a narrow energy gap.

    DOI: 10.3131/jvsj2.56.32

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  29. Monovalent and Mixed-Valent Potassium Salts of [1,2,5]Thiadiazolo[3,4-f][1,10]phenanthroline 1,1-Dioxide: A Radical Anion for Multidimensional Network Structures 査読有り

    Shuku Yoshiaki, Suizu Rie, Awaga Kunio

    INORGANIC CHEMISTRY   50 巻 ( 23 ) 頁: 11859 - 11861   2011年12月

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Inorganic Chemistry  

    A novel phenanthlorine derivative, [1,2,5]thiadiazolo[3,4-f][1,10] phenanthroline 1,1-dioxide (tdapO2), was prepared to act as a radical-anion building block for coordination polymers. The crystal structures and magnetic properties of the monovalent and mixed-valent radical-anion salts K•tdapO2 and K•(tdapO2)2 were elucidated and confirm the possibility of tdapO2 to act as a bridging ligand and its capability to exhibit magnetic ordering at 15 K. © 2011 American Chemical Society.

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  30. Effect of photoinduced charge displacement on organic optoelectronic conversion 査読有り

    Hu, LG; Iwasaki, A; Suizu, R; Noda, Y; Li, B; Yoshikawa, H; Matsushita, MM; Awaga, K; Ito, H

    PHYSICAL REVIEW B   84 巻 ( 20 ) 頁: 205329   2011年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Physical Review B - Condensed Matter and Materials Physics  

    As a significant drawback to organic electronics, poor mobility in organic materials makes it difficult for carriers to make long trips across thin film devices. In the present work, we show that a short carrier trip or even charge displacement can contribute to the functioning of optoelectronics without being influenced by the poor carrier mobility. Our findings are based on analysis of the current-voltage and capacitance-voltage characteristics, as well as the anomalous transient photocurrent of the photocells of a radical material, 4′4-bis(1,2,3,5-dithiadiazolyl). This photoinduced transient current was successfully analyzed based on the total current equation and was interpreted in terms of the polarization current induced by charge displacement in the films. This mechanism provides preliminary information with respect to the development of methods for high-speed organic optoelectronic conversion. © 2011 American Physical Society.

    DOI: 10.1103/PhysRevB.84.205329

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  31. Highly efficient alternating photocurrent from interactive organic-radical dimers: A novel light-harvesting mechanism for optoelectronic conversion 査読有り

    Hu, LG; Iwasaki, A; Suizu, R; Yoshikawa, H; Awaga, K; Ito, H

    CHEMICAL PHYSICS LETTERS   484 巻 ( 4-6 ) 頁: 177 - 180   2010年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemical Physics Letters  

    Thin films of interacting dimers of 4,4′-bis(1,2,3,5-dithiadiazolyl), sandwiched by ITO and Al, exhibit an anomalous transient current, due to a significant imbalance between the hole and electron mobilities and bulk polarization. We propose a new operational principle for organic optoelectronic conversion systems, which efficiently generates alternating photocurrent without being affected by the disadvantages of organic materials, such as poor mobility. © 2009 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.cplett.2009.11.013

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  32. Interactive Radical Dimers in Photoconductive Organic Thin Films 査読有り

    Iwasaki, A; Hu, LG; Suizu, R; Nomura, K; Yoshikawa, H; Awaga, K; Noda, Y; Kanai, K; Ouchi, Y; Seki, K; Ito, H

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   48 巻 ( 22 ) 頁: 4022 - 4024   2009年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Angewandte Chemie - International Edition  

    Fully interactive: Overlap between extended unoccupied molecular orbitals leads to the high photoconductivity of interactive radical dimers. Sandwich-type cells (see picture; ITO=indium tin oxide) comprising highly oriented thin films of a disjoint diradical, 4,4′-bis(1,2,3,5-dithiadiazolyl) (BDTDA) exhibit a photocurrent with a high on/off ratio at reverse bias voltages and photovoltaic behavior at zero bias voltage. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.

    DOI: 10.1002/anie.200900472

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  33. Fe(II) spincrossover complex of [1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 査読有り

    Shuku Yoshiaki, Suizu Rie, Awaga Kunio, Sato Osamu

    CRYSTENGCOMM   11 巻 ( 10 ) 頁: 2065 - 2068   2009年

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CrystEngComm  

    We prepared an iron(II) spin crossover complex with a new ligand, [1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline, which is a 1,10-phenanthroline analogue annulated with a thiadiazole moiety. X-Ray crystal analysis indicated a 3D network structure formed by short S⋯S contacts, and magnetic measurements revealed a broad transition above room temperature. © 2009 The Royal Society of Chemistry.

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  34. Electronic structure of disjoint diradical 4,4 '-bis(1,2,3,5-dithiadiazolyl) thin films 査読有り

    Kanai Kaname, Yoshida Hiroyuki, Noda Yukiko, Iwasaki Akito, Suizu Rie, Tsutumi Jun'ya, Imabayashi Hiroki, Ouchi Yukio, Sato Naoki, Seki Kazuhiko, Awaga Kunio

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   11 巻 ( 48 ) 頁: 11432 - 11436   2009年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Physical Chemistry Chemical Physics  

    The electronic structure of the thiazyl diradical, 4,4′-bis(1,2,3,5- dithiadiazolyl) (BDTDA), has been investigated by ultraviolet photoemission spectroscopy. Stacked BDTDA dimers showed an energy band dispersion of about 0.3 eV for the highest occupied molecular orbital in the direction of the surface normal of the BDTDA solid film. The π-orbital overlap between the stacked dimers therefore evolves into a quasi one-dimensional energy band along the dimer stacking direction. © 2009 the Owner Societies.

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  35. Molecular, crystal, and thin-film structures of octathio[8]circulene: Release of antiaromatic molecular distortion and lamellar structure of self-assembling thin films 査読有り

    Fujimoto, T; Suizu, R; Yoshikawa, H; Awaga, K

    CHEMISTRY-A EUROPEAN JOURNAL   14 巻 ( 20 ) 頁: 6053 - 6056   2008年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemistry - A European Journal  

    Single crystals and thin films of the sunflower 2 was prepared by X-ray single-crystal analysis. Single crystals of the parent compound 1 were grown by slow evaporation of the Et2O solution at room temperature. Single crystals of 2 were obtained as red needles by vacuum sublimation, and X-ray crystal analysis was carried out at 173 K. The space group was found to be the monoclinic P21/n, while it was assigned to the non-centrosymmetric P21 in the Rietveld analysis. The symmetry, obtained in the present re-determination of the crystal structure of 2, reduced the size of the asymmetric unit to one-half molecule. The out-of-plane measurements indicate several diffraction peaks. Thin-film XRD indicated a lamellar structure in which the molecular planes are nearly perpendicular to the substrates.

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  36. Synthesis and characterization of heteroleptic iron(II) thiolate complexes with weak iron-arene interactions 招待有り 査読有り

    Ohta, S; Ohki, Y; Ikagawa, Y; Suizu, R; Tatsumi, K

    JOURNAL OF ORGANOMETALLIC CHEMISTRY   692 巻 ( 21 ) 頁: 4792 - 4799   2007年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.jorganchem.2007.06.027

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  37. Synthesis and structures of cyclic ethynylphosphine ligands 査読有り

    Shiozawa, R; Sakamoto, K

    CHEMISTRY LETTERS   32 巻 ( 11 ) 頁: 1024 - 1025   2003年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1246/cl.2003.1024

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  38. Synthesis and properties of hetero-halogenated TTFs 査読有り

    Suizu, R; Imakubo, T

    ORGANIC & BIOMOLECULAR CHEMISTRY   1 巻 ( 21 ) 頁: 3629 - 3631   2003年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1039/b310822h

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  39. Reaction of silylpentacarbonylmanganese with hydride-transfer reagents: reduction of carbonyl ligands accompanied with Si-C and C-C coupling 査読有り

    Shiozawa, R; Tobita, H; Ogino, H

    JOURNAL OF ORGANOMETALLIC CHEMISTRY   650 巻 ( 1-2 ) 頁: 91 - 95   2002年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/S0022-328X(02)01188-9

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  40. Convenient preparation of Li[(eta(5)-C5Me5)M(CO)(2)] (M = Ru, Fe) by the reaction of (eta(5)-C5Me5)M(CO)(2)H with n-BuLi 査読有り

    Okazaki M, Satoh K, Akagi T, Iwata M, Jung KA, Shiozawa R, Okada H, Ueno K, Tobita H, Ogino H

    JOURNAL OF ORGANOMETALLIC CHEMISTRY   645 巻 ( 1-2 ) 頁: 201 - 205   2002年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/S0022-328X(01)01373-0

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  41. Novel reaction of silyl carbonyl complexes with hydride-transfer reagents: Reduction of a carbonyl ligand and coupling with a silyl group 査読有り

    Shiozawa, R; Tobita, H; Ogino, H

    ORGANOMETALLICS   17 巻 ( 16 ) 頁: 3497 - 3504   1998年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/om9802111

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  42. Reaction of silyl(carbonyl)iron complexes with LiAlH4 giving methylsilanes: Reduction of a carbonyl ligand and coupling with a silyl group 査読有り

    H Tobita, R Shiozawa, H Ogino

    CHEMISTRY LETTERS   ( 8 ) 頁: 805 - 806   1997年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    Treatment of CpFe(CO)(2)SiR3 (R-3 = (pTol)(2)H, ((p)Tol)(2)Me, MePh(1-Nap); 1-Nap = 1-naphthyl) with LiAlH4 in ether or THF at room temperature gave CH3SiR3 as a major product in moderate to high yield. The labeling experiments using LiAlD4 and CpFe((CO)-C-13)(2)SiR(pTol)(2) (R = H, Me) proved unambiguously that the carbonyl ligand is reduced with LiAlH4 and coupled with the silyl group to give the methylsilane.

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  43. Reaction of silyl(carbonyl)iron complexes with LiAlH4 giving methylsilanes: Reduction of a carbonyl ligand and coupling with a silyl group

    Tobita H, Shiozawa R, Ogino H

    CHEMISTRY LETTERS   ( 8 ) 頁: 805 - 806   1997年

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    記述言語:日本語  

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  1. ヨウ素化合物の機能と応用

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    シーエムシー出版  2005年 

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    担当ページ:193-206   記述言語:日本語 著書種別:学術書

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MISC 10

  1. ハニカムネットワークを有するBDTDA単層膜の低速電子線回折による構造解析

    水津理恵, 水津理恵, 花本大智, 山本真幸, 白澤徹郎, 坂本一之  

    分子科学討論会講演プログラム&amp;要旨(Web)11th 巻   頁: ROMBUNNO.2C09 (WEB ONLY)   2017年

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    記述言語:日本語  

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    水津理恵, 森岡健太, 阿波賀邦夫, 坂本一之  

    日本化学会講演予稿集94th 巻 ( 2 ) 頁: 261   2014年3月

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  3. 環状チアジルラジカル分子の扱着によるAg薄膜の量子井戸準位の変調

    林田崇志, 水津理恵, 珠玖良昭, 阿波賀邦夫, 坂本一之  

    日本物理学会講演概要集68 巻 ( 2 ) 頁: 811   2013年8月

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  4. 実デバイス環状チアジルラジカル分子薄膜の電子構造

    森岡健太, 水津理恵, 阿波賀邦夫, 坂本一之  

    日本物理学会講演概要集68 巻 ( 2 ) 頁: 803 - 803   2013年8月

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  5. ハニカム格子状に配列したラジカル分子BDTDA単層膜のSTM/S観察

    山本真幸, 水津理恵, MISHRA P, DUTTA S, 吉澤俊介, 坂本一之, 阿波賀邦夫, 中山知信, 若林克法, 内橋隆  

    日本物理学会講演概要集68 巻 ( 1 ) 頁: 926   2013年3月

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  6. 環状チアジルバイラジカルBDTDA薄膜の電子構造

    水津理恵, 森岡健太, 阿波賀邦夫, 坂本一之  

    分子科学討論会講演プログラム&amp;要旨(Web)7th 巻   頁: ROMBUNNO.3P045 (WEB ONLY)   2013年

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    記述言語:日本語  

    J-GLOBAL

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  7. 有機ビラジカル分子薄膜の電子構造

    金井要, 古池晴信, 水津理恵, 阿波賀邦夫, 間瀬一彦, 久保孝史  

    J. Vac. Soc. Jpn56 巻   頁: 32 - 38   2013年

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    記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

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  8. 27pPSA-17 環状チアジルラジカル分子の吸着によるAg薄膜の量子井戸準位の変調(領域9ポスターセッション,領域9(表面・界面,結晶成長))

    林田 崇志, 水津 理恵, 珠玖 良昭, 阿波賀 邦夫, 坂本 一之  

    日本物理学会講演概要集68 巻 ( 0 ) 頁: 811 - 811   2013年

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    記述言語:日本語   出版者・発行元:一般社団法人 日本物理学会  

    CiNii Books

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  9. Cu(111)上に作製した環状チアジルラジカルBDTDA超薄膜の構造と電子状態

    山本真幸, 水津理恵, MISHRA P, 中山知信, 阿波賀邦夫, 坂本一之, 内橋隆  

    日本物理学会講演概要集67 巻 ( 2 ) 頁: 816 - 816   2012年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    CiNii Books

    J-GLOBAL

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  10. 30aYF-8 非線形伝導を示すNT_3GaCl_4における電流発振現象とEPR(30aYF θ-ET系等,電荷秩序,非線形伝導,領域7(分子性固体・有機導体))

    野村 賢司, 松下 朱知雄, 水津 理恵, 阿波賀 邦夫, 岸田 英夫  

    日本物理学会講演概要集64 巻 ( 1 ) 頁: 855 - 855   2009年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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▼全件表示

科研費 4

  1. 原子レベルで制御された原子層結晶界面での新奇スピン物性

    研究課題/研究課題番号:22H01957  2022年4月 - 2025年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    坂本 一之, 宮町 俊生, 小田 竜樹, 水津 理恵

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    担当区分:研究分担者 

    固体表面上に作製した原子層結晶は、スピン軌道相互作用と表面垂直方向の反転対称性の破れにより、非磁性体であってもスピン偏極電子バンドを有するため、スピン偏極電流が流れる。原子層結晶上に磁性層を成長させ、原子層結晶にスピン偏極電流を流すとラシュバ・エデルシュタイン効果により界面にスピンが蓄積することが期待できる。本研究では、このスピン蓄積機構を解明することで、原子層結晶研究の新しい展開を切り拓くとともに、従来型の記憶素子を凌駕する原子層結晶を用いた次世代スピントロニクスデバイスの具現化への道筋をつける。
    固体表面上に作製した原子1層から数層の原子層結晶では、スピン軌道相互作用と層垂直方向の反転対称性に起因したスピン偏極電子バンドが生じる。原子層結晶の両端に電位差をかけるとこのバンドを介したスピン偏極電流が流れ、スピンホール効果によりその向きに依存して原子層の上もしくは下に電子スピンは移動するはずである。このことから、原子層結晶上に磁性層を成長させると、原子層結晶との界面でラシュバ・エデルシュタイン効果によるスピン蓄積機構が期待される。研究代表者は、これまで原子層結晶の構造に由来する、理想的なラシュバ効果では説明できない層垂直方向を向く特異な偏極スピンの存在や、ラシュバ効果が小さい重元素原子層結晶以外の系においても軌道角運動量の影響が大きければスピン偏極バンドが生成することを報告してきた。このことは、原子層結晶の構造などを制御することでスピンの向きだけでなく、スピン流の偏極度も制御可能であり、これまでにない概念のスピントロニクスデバイスが創出できる可能性を意味している。そこで、原子層結晶のスピン偏極電子バンドを大きく変調させることなく磁性層を成長させることを目的に、基板との相互作用が弱いことが期待される磁性分子を含む種々の有機分子を成長させた原子層結晶のバンド構造を測定した。その結果、In 2層からなる原子層結晶の場合、どの有機分子を蒸着してもバンド構造が大きく変調しないこと、TlとPbの合金1層からなる原子層結晶の場合は有機分子がCoを含む場合はCoとTlの強い相互作用のためにバンド構造が大きく崩れるものの、それ以外の有機分子では変調がほとんど見られなかった。現在は微小電流を流すことでの原子・分子構造やバンド構造への影響を調べている。また、主課題以外にも原子層結晶と同じくスピン偏極電子バンドを有するトポロジカル絶縁体への磁性有機分子蒸着の影響も調べた。
    磁性有機分子蒸着による原子層結晶の電子バンドへの影響を明らかにした。また、原子層結晶として、超伝導が発現するIn 2層の原子層結晶を用いた場合、蒸着分子によって超伝導転移温度が変わることとその要因を明らかにした。In原子層超伝導体にCuPc分子を蒸着すると、転移温度が上昇する。この要因はCuPcからIn層へのわずかなホールドープであると報告されていたが、ZnPcを蒸着したところCuPcよりも転移温度が大きく上がったものの電子バンドの測定からはそれに対応する大きなホールドープは認められなかった。このことから、転移温度の変化が分子から原子層結晶への電荷移動ではなく、分子吸着による原子層結晶の最外層の電子軌道の歪み、いわゆるプッシュバック効果であると結論した。また、電子親和力が大きいことから大きなホールドープが期待されるPDCDA分子を蒸着してIn原子層結晶の超伝導転移温度の変化を調べたが、ホールドープは観測されず、転移温度も蒸着量に依存して下がり、常伝導状態の面抵抗率も大きくなって絶縁体的な振る舞いを示した。このような変化はIn原子層結晶上に規則正しく配列するPc分子では観測されなかったことと、PCTDA分子は局所的に配列が大きく乱れていることから、このIn原子層結晶への局所的なポテンシャルの乱れが超伝導を壊していると結論した。In原子層超伝導体にCoPc、FePc、MnPcなどの磁性有機分子を蒸着すると超伝導転移温度は下がるが、原子層結晶の電子状態、磁性有機分子の分子軌道は大きく変調しなかった。これらの結果は当初の計画以上の成果があると言える。そのため、原子層結晶のスピン偏極電流が磁性層に与える影響の測定が計画通りに進まなかったものの、全体としておおむね順調に進展していると考えている。
    本年度は、昨年度得た結果をより発展させるため、以下のものを計画している。 (1)基板にわずかな電流を流した時の原子層結晶のバンド構造の変調と吸着分子の分子軌道の変調に関する知見を角度分解光電子分光で得る、(2)基板に電流を流した状態でスピン分解光電子分光とスピン偏極操作トンネル顕微鏡により分子軌道のスピン状態に関する情報を得ること、(3)昨年度は達成できなかった単分子で強い保磁力を示すダブルデッカー型テルビウム錯体TbPc2の合成と、(4)同分子蒸着によるIn原子層結晶とTlPb原子層結晶のバンド構造への影響に関する知見を得ることと、(5)得られた結果を第一原理計算から得た結果と比較・議論することで、原子層結晶-磁性有機分子界面での電子スピン物性を明らかにすることを計画している。また、超高真空中で作製した原子層結晶およびその上に成長させて磁性層は、大気にさらすと簡単に酸化すると想像できる。そこで、超高真空中で作製した試料の電子状態を破壊せずに大気中に取り出すため、超高真空中でイオン液体による試料をキャップすることを考えている。そこで、(6)現状では存在しない真空中でのイオン液体滴下装置を作製する。また、(7)イオン液体のキャップ材としての可能性を滴下前後の伝導測定から議論する。光電子分光測定は研究代表者の坂本が所有するスピン・角度分解光電子分光装置と国内外の放射光施設を用いて行う。イオン液体滴下装置の作製は坂本が行う。走査トンネル顕微鏡測定は研究分担者の宮町が所有するスピン偏極走査トンネル顕微鏡装置を用いて行い、新奇磁性有機分子の合成は研究分担者の水津が行う。第一原理計算は研究分担者の小田が担当する。

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  2. 強相関ラジカル分子構造体のライングラフ物性

    研究課題/研究課題番号:JPMJPR21A9  2021年10月 - 2025年3月

    科学技術振興機構  戦略的創造研究推進事業さきがけ 

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    担当区分:研究代表者 

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  3. 強相関ラジカル分子2次元ネットワークの物性探索と制御

    研究課題/研究課題番号:20H02707  2020年4月 - 2023年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    水津 理恵, 坂本 一之, 内橋 隆

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    担当区分:研究代表者 

    配分額:18200000円 ( 直接経費:14000000円 、 間接経費:4200000円 )

    本研究では、分子間に強い相互作用をもつ『強相関ラジカル分子』を用いて基板上に『自己集積二次元ネットワーク』を作製し、その物性の探索と制御を行う。構成ユニットをラジカル分子にすることで、電子対形成の安定化を受けていない不対電子が機能発現の源となる。また静電的相互作用や不対電子間の磁気的交換相互作用などの分子間相互作用に加えて、分子‐基板相互作用を組み合わせることで、バルク結晶では実現できない二次元ネットワークの作製を目指す。その二次元ネットワーク特有の電子構造に由来した新奇物性を探索し、さらに大きな空孔を利用した電気化学的な手法を用いたバンドフィリング制御による電子物性の制御方法を確立する。
    二次元ネットワークの構成分子として、フェナジン部位をもつトリプチセン誘導体Trip-Phzを合成した。結晶中において、π-π相互作用によってハニカム構造を形成していた。この分子配置を元にバンド計算を行ったところ、ディラック・コーンだけでなく、フラットバンドが含まれていることがわかった。そこでAg(111)の清浄表面上にTrip-Phzを蒸着させたところ、ハニカム格子が形成されていることがわかった。その格子定数は、単結晶のものと比べると20%ほど小さくなっており、エピタキシャル成長のためと考えられる。この物質の電子バンドを実験的に直接観測するため、有機分子仕様の光電子分光装置を導入した。
    学術的な意義として、3回対称性をもつ分子でハニカム格子をつくることで、必然的にディラック・コーンおよびフラットバンドが発現されることを提唱し、それを実験的に立証するための試料の作製方法の確立が挙げられる。バルク結晶の構造を基板上で構築することで、分子配列と電子構造の観測が可能となる。社会的意義としては、爆発的に増加している情報量を処理するためのデバイスの創出に関して、本研究の研究対象である分子性ハニカム格子は、バンドフィリングよって電子の有効質量を制御することが可能であり、全く新しい作動原理を持つデバイス創出の種となることが挙げられる。

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  4. 遷移金属錯体を用いた新規なケイ素-炭素結合形成反応の研究

    研究課題/研究課題番号:99J01418  1999年1月 - 2001年3月

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

    塩沢 理恵

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    担当区分:研究代表者 

    配分額:1800000円 ( 直接経費:1800000円 )

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