91 results on '"Hiroki Akutsu"'
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2. Electronic Heat Capacity and Lattice Softening of Partially Deuterated Compounds of κ-(BEDT-TTF)2Cu[N(CN)2]Br
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Yuki Matsumura, Shusaku Imajo, Satoshi Yamashita, Hiroki Akutsu, and Yasuhiro Nakazawa
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organic superconductor ,strong electron correlations ,heat capacity ,Mott transition ,Crystallography ,QD901-999 - Abstract
Thermodynamic investigation by calorimetric measurements of the layered organic superconductors, κ-(BEDT-TTF)2Cu[N(CN)2]Br and its partially deuterated compounds of κ-(d[2,2]-BEDT-TTF)2Cu[N(CN)2]Br and κ-(d[3,3]-BEDT-TTF)2Cu[N(CN)2]Br, performed in a wide temperature range is reported. The latter two compounds were located near the metal–insulator boundary in the dimer-Mott phase diagram. From the comparison of the temperature dependences of their heat capacities, we indicated that lattice heat capacities of the partially deuterated compounds were larger than that of the pristine compound below about 40 K. This feature probably related to the lattice softening was discussed also by the sound velocity measurement, in which the dip-like structures of the Δv/v were observed. We also discussed the variation of the electronic heat capacity under magnetic fields. From the heat capacity data at magnetic fields up to 6 T, we evaluated that the normal-state γ value of the partially deuterated compound, κ-(d[3,3]-BEDT-TTF)2Cu[N(CN)2]Br, was about 3.1 mJ K−2 mol−1. Under the magnetic fields higher than 3.0 T, we observed that the magnetic-field insulating state was induced due to the instability of the mid-gap electronic state peculiar for the two-dimensional dimer-Mott system. Even though the volume fraction was much reduced, the heat capacity of κ-(d[3,3]-BEDT-TTF)2Cu[N(CN)2]Br showed a small hump structure probably related to the strong coupling feature of the superconductivity near the boundary.
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- 2021
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3. Structures and Properties of New Organic Conductors: BEDT-TTF, BEST and BETS Salts of the HOC2H4SO3− Anion
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Hiroki Akutsu, Yuta Koyama, Scott S. Turner, Keigo Furuta, and Yasuhiro Nakazawa
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organic conductors ,bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) ,bis(ethylenediseleno)tetrathiafulvalene (BEST) ,bis(ethylenedithio)tetraselenafulvalene (BETS) ,electrical resistivity ,magnetic susceptibility ,Crystallography ,QD901-999 - Abstract
New bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF)-, bis(ethylenediseleno)tetrathiafulvalene (BEST)- and bis(ethylenedithio)tetraselenafulvalene (BETS)-based organic charge-transfer (CT) salts—α-(BEDT-TTF)3(HOC2H4SO3)2 (1), β-(BEST)3(HOC2H4SO3)2·H2O (2) and α-(BETS)2(HOC2H4SO3)·H2O (3)—have been prepared. Salts 1 and 2 show semiconducting behaviour. Salt 3, which is almost isostructural to α-(BETS)2I3, shows metallic behaviour down to 70 K and then shows a broader metal–insulator transition than that of α-(BETS)2I3. The reason for the difference in behaviour is estimated by the comparison of the Madelung energies of the full set of patterns of possible donor’s charge-ordered and anion’s disordered states.
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- 2020
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4. Magnetic and Electronic Properties of π-d Interacting Molecular Magnetic Superconductor κ-(BETS)2FeX4 (X = Cl, Br) Studied by Angle-Resolved Heat Capacity Measurements
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Shuhei Fukuoka, Sotarou Fukuchi, Hiroki Akutsu, Atsushi Kawamoto, and Yasuhiro Nakazawa
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π-d system ,thermodynamic measurement ,superconductivity ,antiferromagnetism ,single crystal heat capacity measurement ,magnetic conductor ,Crystallography ,QD901-999 - Abstract
Thermodynamic picture induced by π-d interaction in a molecular magnetic superconductor κ-(BETS)2FeX4 (X = Cl, Br), where BETS is bis(ethylenedithio)tetraselenafulvalene, studied by single crystal calorimetry is reviewed. Although the S = 5/2 spins of Fe3+ in the anion layers form a three-dimensional long-range ordering with nearly full entropy of Rln6, a broad hump structure appears in the temperature dependence of the magnetic heat capacity only when the magnetic field is applied parallel to the a axis, which is considered as the magnetic easy axis. The scaling of the temperature dependence of the magnetic heat capacity of the two salts is possible using the parameter of |Jdd|/kB and therefore the origin of the hump structure is related to the direct magnetic interaction, Jdd, that is dominant in the system. Quite unusual crossover from a three-dimensional ordering to a one-dimensional magnet occurs when magnetic fields are applied parallel to the a axis. A notable anisotropic field-direction dependence against the in-plane magnetic field was also observed in the transition temperature of the bulk superconductivity by the angle-resolved heat capacity measurements. We discuss the origin of this in-plane anisotropy in terms of the 3d electron spin configuration change induced by magnetic fields.
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- 2019
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5. Chemical Modifications of BDH-TTP [2,5-Bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene]: Control of Electron Correlation
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Hiroki Akutsu and Jun-ichi Yamada
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organic molecular conductor ,strongly correlated electron system ,electron correlation ,superconductivity ,chemical modification ,donor molecule ,itinerant electron system ,bandwidth ,Crystallography ,QD901-999 - Abstract
Organic molecular conductors with a strongly correlated electron system, in which the itinerancy of electrons (or holes) and the electron correlation (U/W, U, the on-site Coulomb repulsion, W, the bandwidth) compete with each other, are promising candidates for achieving superconductivity and also for exploring remarkable physical properties induced by external stimuli such as pressure, light, voltage and current. Our synthetic approach to the construction of strongly correlated organic electron systems is based on chemical modifications to the donor molecule BDH-TTP [2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] capable of producing metallic CT (charge-transfer) salts stable down to low temperatures (4.2–1.5 K). This aims at enhancing the electron correlation in the itinerant electron system by decreasing the bandwidth. Chemical modifications of BDH-TTP such as ring expansion of two outer dithiolane rings, replacement of one sulfur atom in an outer dithiolane ring with an oxygen atom and introduction of two methyl substituents into an outer ditiolane ring led to BDA-TTP [2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene], DHOT-TTP [2-(1,3-dithiolan-2-ylidene)-5-(1,3-oxathiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] and DMDH-TTP [2-(4,5-dimethyl-1,3-dithiolan-2-ylidene)-5-(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene], respectively. In this review, the physical properties and the crystal and electronic structures of molecular conductors derived from these donor molecules will be described.
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- 2012
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6. Single-Component Charge-Transfer Crystals Based on Spin-Carrying TCNQ (7,7,8,8-Tetracyanoquinodimethane) Derivatives
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Shin’ichi Nakatsuji, Jun-ichi Yamada, Hiroki Akutsu, and Hideto Suzuki
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CT complex ,nitroxide ,TCNQ ,redox property ,magnetic property ,crystal structure ,Crystallography ,QD901-999 - Abstract
Three TCNQ derivatives carrying nitroxide radicals (3a–3c) were prepared and were found to form single-component charge-transfer (CT) complexes by self-assembly, in which outer nitroxide groups of a couple of different molecules work as donors and the inner TCNQ unit of another molecule as an acceptor. While the CT interactions found for the TEMPO (2,2,6,6-tetramethylpiperidin-1-oxy) derivative 3a and the PROXYL (2,2,5,5-tetramethylpirrolidin-1-oxy) derivative 3b are point-to-face fashion between the oxygen atom of each nitroxide group and the six-membered ring of inner TCNQ unit, the CT interactions found for the PO (2,2,5,5-tetramethyl-3-pyrrolin-1-oxy) derivative 3c are point-to-point contacts between the oxygen atoms of outer nitroxide groups and the carbon atoms of a couple of cyano groups.
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- 2012
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7. A New BEDT-TTF-Based Organic Charge Transfer Salt with a New Anionic Strong Acceptor, N,N'-Disulfo-1,4-benzoquinonediimine
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Scott S. Turner, Shin’ichi Nakatsuji, Jun-ichi Yamada, and Hiroki Akutsu
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organic conductor ,BEDT-TTF ,hole doping effect ,anionic acceptor ,transport properties ,magnetic properties ,Crystallography ,QD901-999 - Abstract
A novel organic dianion, N,N'-Disulfo-1,4-benzoquinonediimine (1) has been prepared, which is a strong electron acceptor. The reduction potential of the PPh4 salt indicates that 1 is a stronger acceptor than DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone). The dianionic acceptor provided a BEDT-TTF salt, (BEDT-TTF)41·3H2O, the structures and physical properties of which are reported.
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- 2012
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8. Thermodynamic Picture of Dimer-Mott Organic Superconductors Revealed by Heat Capacity Measurements with External and Chemical Pressure Control
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Yasuhiro Nakazawa, Shusaku Imajo, Yuki Matsumura, Satoshi Yamashita, and Hiroki Akutsu
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organic superconductor ,dimer-Mott system ,heat capacity ,electron correlations ,d-wave ,pressure ,Crystallography ,QD901-999 - Abstract
This article reviews and discusses the thermodynamic properties of dimer-Mott-type molecular superconductive compounds with (BEDT-TTF)2X composition, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene and X denotes counter-anions, respectively. We focus mainly on the features occurring in the κ-type structure in which the d-wave superconductive phase appears depending on the Coulomb repulsion U and the bandwidth W, which is tunable by external and chemical pressures. First, we report the high-pressure ac (alternating current) calorimetry technique and experimental system constructed to measure single-crystal samples of molecule-based compounds to derive low-temperature thermodynamic parameters. Using extremely small resistance chips as a heater and a thermometer allows four-terminal detection of an accurate temperature and its oscillation in the sample part with sufficient sensitivity. From the analyses of the temperature dependence of the ac heat capacity of κ-(BEDT-TTF)2Cu(NCS)2 under external pressures, we discuss the changes in the peak shape of the thermal anomaly at the superconductive transition temperature Tc at various external pressures p. The rather sharp peak in CpT−1 at Tc = 9.1 K with a strong coupling character at ambient pressure is gradually reduced to weaker coupling as the pressure increases to 0.45 GPa concomitant with suppression of the transition temperature. This feature is compared with the systematic argument of the chemical–pressure effect on the basis of thermal anomalies around the superconductive transition of κ-(BEDT-TTF)2X compounds and other previously studied typical dimer-Mott 2:1 compounds. Finally, the discussion is extended to the chemical pressure effect on the normal state electronic heat capacity coefficient γ obtained by applying magnetic fields higher than Hc2 and the residual γ*, which remains in the superconductive state due to the induced electron density of states around the node structure. From the overall arguments with respect to both chemical and external pressures, we suggest that a crossover of the electronic state inside the superconductive phase occurs and the coupling strength of electron pairs varies from the electron correlation region near the metal-insulator boundary to the band picture region.
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- 2018
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9. Asymmetric N-heteroacene tetracene analogues as potential n-type semiconductors
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Andrew J. P. White, Mark Oxborrow, Max Attwood, Anthony Maho, Wern Ng, Sandrine Heutz, Joseph H. L. Hadden, Hao Wu, Hiroki Akutsu, Dong Kuk Kim, Engineering & Physical Science Research Council (EPSRC), and Engineering & Physical Science Research Council (E
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Technology ,Materials science ,Materials Science ,Heteroatom ,Materials Science, Multidisciplinary ,Crystal structure ,Physics, Applied ,ACENES ,chemistry.chemical_compound ,Materials Chemistry ,Molecule ,Thin film ,0912 Materials Engineering ,HOMO/LUMO ,0306 Physical Chemistry (incl. Structural) ,PENTACENE ,Science & Technology ,CRYSTAL ,DERIVATIVES ,Physics ,SUBSTITUTION ,0303 Macromolecular and Materials Chemistry ,General Chemistry ,STATE ,Organic semiconductor ,Crystallography ,Tetracene ,chemistry ,Physical Sciences ,THIN-FILM TRANSISTORS ,Single crystal - Abstract
In the search for high performance n-type organic semiconductors (OSCs) a simple strategy might be substitution of aromatic CH groups for nitrogen heteroatoms. Here, we report the synthesis and characterisation of two novel N-heteroacene compounds, namely, 1,5,12-triazatetracene (TrAT1) and 2,5,12-triazatetracene (TrAT2). Their potential as n-type materials is evaluated against 5,12-diazatetracene (DAT) by UV/vis and EPR spectroscopy, cyclic voltammetry, DFT, single crystal X-ray diffraction and thin film characterisation. Increasing the number of N-heteroatoms was found to stabilise the HOMO and LUMO leading to electron affinities for TrAT1 and TrAT2 of ca. −4 eV. Both compounds were found to exhibit columns of co-facial π-stacked molecules. For TrAT1, molecules are also linked by hydrogen bonding, while the crystal structure of TrAT2 was found to be inherently disordered. Thin films of DAT, TrAT1 and TrAT2 were grown by organic molecular beam deposition (OMBD) and found to form discontinuous films, where TrAT1 exhibited a preferential orientation.
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- 2021
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10. Structural, magnetic and Mössbauer spectroscopic studies of the [Fe(3-bpp)2](CF3COO)2 complex: role of crystal packing leading to an incomplete Fe(<scp>ii</scp>) high spin ⇋ low spin transition
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Djulia Onggo, Varimalla Raghavendra Reddy, Hiroki Akutsu, Ashis Bhattacharjee, Yasuhiro Nakazawa, Hari Sutrisno, and Kristian Handoyo Sugiyarto
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Diffraction ,Materials science ,Transition temperature ,Spin transition ,General Chemistry ,Condensed Matter Physics ,Crystal ,chemistry.chemical_compound ,Crystallography ,chemistry ,Mössbauer spectroscopy ,Pyridine ,General Materials Science ,Single crystal ,Spin-½ - Abstract
Single crystal X-ray diffraction, magnetic and 57Fe Mossbauer spectroscopic studies of a new iron(II)-based spin transition complex – [Fe(3-bpp)2](CF3COO)2 (bpp = 2,6-bis(pyrazol-3-yl)pyridine) are reported. The complex exhibits an incomplete thermal high spin (HS) low spin (LS) transition at ∼226 K which is not associated with any crystallographic transition. Only one of the two crystallographic iron(II) sites undergoes the spin transition, while the other HS site remains invariant of temperature down to 10 K. The origin of the incomplete spin transition is understood by analysing the nature of crystal packing below and above the transition temperature with special attention to the degree of distortion. The present study shows the role of the degree of distortion associated with the cations in the [Fe(3-bpp)2]2+ spin transition complexes.
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- 2021
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11. Chiral metal down to 4.2 K - a BDH-TTP radical-cation salt with spiroboronate anion B(2-chloromandelate)2−
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Hiroshi Nishimoto, Yasuhiro Nakazawa, Michael Brannan, Tomofumi Kadoya, Lee Martin, Hiroki Akutsu, Toby J. Blundell, and Jun-ichi Yamada
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chemistry.chemical_classification ,Chiral ligand ,Metals and Alloys ,Salt (chemistry) ,General Chemistry ,Crystal structure ,Catalysis ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Metal ,Crystallography ,chemistry ,Radical ion ,visual_art ,Materials Chemistry ,Ceramics and Composites ,visual_art.visual_art_medium ,Racemic mixture ,Enantiomer ,Chirality (chemistry) - Abstract
We report the first example of a chiral BDH-TTP radical-cation salt. Chirality is induced in the structure via the use of a chiral spiroboronate anion where three stereocentres are present, one on each chiral ligand and one on the boron centre. Despite starting from a labile racemic mixture of BS and BR enantiomers, only one enantiomer is present in the crystal lattice. The anions pack in a novel double anion layer which is the thickest anion layer found in a BDH-TTP salt. This material is chiral and shows metallic behaviour down to at least 4.2 K.
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- 2021
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12. Structure and Properties of a New Purely Organic Magnetic Conductor, δ′-(BEDT-TTF)2(PO-CONHCH(cyclopropyl)SO3)·1.7H2O
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Akiko Kohno, Scott S. Turner, Yasuhiro Nakazawa, and Hiroki Akutsu
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chemistry.chemical_classification ,chemistry.chemical_compound ,Crystallography ,chemistry ,010405 organic chemistry ,Salt (chemistry) ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Tetrathiafulvalene ,0104 chemical sciences ,Ion ,Conductor - Abstract
A new bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF)-based salt with an organic magnetic anion, PO-CONHCH(cyclopropyl)SO3−, has been prepared (PO = 2,2,5,5-tetramethyl-3-pyrrolin-1-oxyl free radi...
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- 2020
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13. Different electronic states of isomorphous chiral vs. racemic organic conducting salts, β′′-(BEDT-TTF)2(S- and rac-PROXYL-CONHCH2SO3)
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Satoshi Yamashita, Akiko Kohno, Scott S. Turner, Hiroki Akutsu, and Yasuhiro Nakazawa
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Materials science ,Point reflection ,02 engineering and technology ,Orders of magnitude (numbers) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Electronic states ,Metal ,Crystallography ,Chemistry (miscellaneous) ,Electrical resistivity and conductivity ,visual_art ,Atom ,visual_art.visual_art_medium ,General Materials Science ,0210 nano-technology ,Electronic band structure - Abstract
The chiral and racemic salts β′′-(BEDT-TTF)2(S- and rac-PROXYL-CONHCH2SO3) (S-2 and rac-2) are almost isomorphous apart from a deviation in the C–H bond direction at the chiral centre. Both salts are metallic at room temperature, with similar broad metal-insulator transitions. Band structure calculations of the chiral and racemic salts indicate that both electronic structures are quite similar. However, at 30 K, S-2 has a resistivity that is nearly three orders of magnitude higher than that of rac-2. The results suggest a significant effect of the broken inversion symmetry, due to the positional change of only one atom.
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- 2020
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14. Exceptionally high temperature spin crossover in amide-functionalised 2,6-bis(pyrazol-1-yl)pyridine iron(ii) complex revealed by variable temperature Raman spectroscopy and single crystal X-ray diffraction
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Pierre Le Maguere, Max Attwood, Lee Martin, Scott S. Turner, Hiroki Akutsu, and Toby J. Blundell
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Inorganic Chemistry ,symbols.namesake ,Crystallography ,Materials science ,Differential scanning calorimetry ,Spin states ,Hydrogen bond ,Spin crossover ,X-ray crystallography ,symbols ,Crystal structure ,Raman spectroscopy ,Single crystal - Abstract
The synthesis of a novel amide-functionalised 2,6-bis(pyrazol-1-yl)pyridine-4-carboxamide ligand (bppCONH2) is described. The complex salts [Fe(bppCONH2)2](BF4)2 and [Fe(bppCONH2)2](ClO4)2 were synthesised and characterised by SQUID magnetometry, differential scanning calorimetry, variable temperature Raman spectroscopy and single crystal X-ray diffraction. DSC measurements of [Fe(bppCONH2)2](BF4)2 indicate a spin-crossover (SCO) transition with T↑ at 481 K and T↓ at 461 K, showing a 20 K hysteresis. DSC for the perchlorate salt shows an SCO transition with T↑ at 459 K and T↓ at 445 K with a 14 K hysteresis. For the BF4− salt analysis of low and high-spin state crystal structures at 101, 290 and 500 K, suggest stabilisation of the low spin state due to the formation of 1D hydrogen-bonded cationic chains. Variable temperature Raman studies of the BF4 salt support the presence of a high temperature SCO. It is speculated that the presence of hysteresis may be attributed to differences in the inter-molecular hydrogen bonding in the low spin and high spin states.
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- 2021
15. Structures and Properties of New Organic Molecule-Based Metals, (D)2BrC2H4SO3 [D = BEDT-TTF and BETS]
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Hiroki Akutsu, Yuta Koyama, Yasuhiro Nakazawa, and Scott S. Turner
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crystal structure ,Materials science ,band structure ,Crystal structure ,organic anions ,Metal ,organic conductors ,chemistry.chemical_compound ,Electrical resistivity and conductivity ,Materials Chemistry ,Molecule ,electrocrystallization ,Electronic band structure ,QD1-999 ,biology ,Magnetic susceptibility ,Electronic, Optical and Magnetic Materials ,Chemistry ,Crystallography ,chemistry ,Chemistry (miscellaneous) ,visual_art ,visual_art.visual_art_medium ,biology.protein ,electrical resistivity ,magnetic susceptibility ,Tetrathiafulvalene ,Organic anion - Abstract
An organic anion, 2-bromoethanesulfonate (BrC2H4SO3−), provides one bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and two bis(ethylenedithio)tetraselenafulvalene (BETS) salts, the compositions of which are β’’-β’’-(BEDT-TTF)2BrC2H4SO3 (1), β’’-β’’-(BETS)2BrC2H4SO3 (2), and θ-(BETS)2BrC2H4SO3 (3), respectively. Compound 1 shows a metal–insulator transition at around 70 K. Compound 2 is isomorphous to 1, and 3 is polymorphic with 2. Compounds 2 and 3 show metallic behavior at least down to 4.2 K. The pressure dependence of the electrical resistivity of 1 is also reported.
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- 2021
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16. First Molecular Superconductor with the Tris(Oxalato)Aluminate Anion, β″-(BEDT-TTF)4(H3O)Al(C2O4)3·C6H5Br, and Isostructural Tris(Oxalato)Cobaltate and Tris(Oxalato)Ruthenate Radical Cation Salts
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Yasuhiro Nakazawa, Shusaku Imajo, Toby J. Blundell, Hiroki Akutsu, Michael Brannan, Lee Martin, and Joey Mburu-Newman
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Tris ,Chemistry ,Aluminate ,Metal ions in aqueous solution ,02 engineering and technology ,Crystal structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Paramagnetism ,Crystallography ,chemistry.chemical_compound ,Metallate ,Radical ion ,Chemistry (miscellaneous) ,Materials Chemistry ,Isostructural ,0210 nano-technology ,molecular conductor ,superconductor ,metal ,semiconductor ,BEDT-TTF ,tris(oxalato)metallate - Abstract
Peter Day’s research group reported the first molecular superconductor containing paramagnetic metal ions in 1995, β″-(BEDT-TTF)4(H3O)Fe(C2O4)3·C6H5CN. Subsequent research has produced a multitude of BEDT-TTF-tris(oxalato)metallate salts with a variety of structures and properties, including 32 superconductors to date. We present here the synthesis, crystal structure, and conducting properties of the newest additions to the Day series including the first superconductor incorporating the diamagnetic tris(oxalato)aluminate anion, β″-(BEDT-TTF)4(H3O)Al(C2O4)3·C6H5Br, which has a superconducting Tc of ~2.5 K. β″-(BEDT-TTF)4(H3O)Co(C2O4)3·C6H5Br represents the first example of a β″ phase for the tris(oxalato)cobaltate anion, but this salt does not show superconductivity.
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- 2021
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17. New Spin-Crossover Compounds Containing the [Ni(mnt)] Anion (mnt = Maleonitriledithiolate)
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Peter N. Horton, Scott S. Turner, Hiroki Akutsu, Volker Schünemann, Simon J. Coles, and Joanna Daniell
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Pyrazine ,Chemistry ,Cationic polymerization ,spin-crossover ,molecular magnets ,magnetic materials ,molecular materials ,Electronic, Optical and Magnetic Materials ,Ion ,Magnetization ,chemistry.chemical_compound ,Crystallography ,Chemistry (miscellaneous) ,Spin crossover ,Mössbauer spectroscopy ,Pyridine ,Materials Chemistry ,QD1-999 ,Single crystal - Abstract
Two novel salts containing the anion [Ni(mnt)2]− (mnt = maleonitriledithiolate) have been synthesized. The counter-ions, [Fe(II)(L1 or L2)2], are cationic complexes where L1 and L2 are methylated derivatives of 2,6-bis(pyazolyl)pyridine or pyrazine, which are similar to ligands found in a series of spin-crossover (SCO) complexes. Both salts are characterized by variable temperature single crystal X-ray diffraction and bulk magnetization measurements. Compound 1, [Fe(II)(L1)2][Ni(mnt)2]2 displays an incomplete and gradual SCO up to 300 K, followed by a more rapid increase in the high-spin fraction between 300 and 350 K. Compound 2, [Fe(II)(L2)2][Ni(mnt)2]2.MeNO2, shows a gradual, but more complete SCO response centered at 250 K. For compound 2, the SCO is confirmed by variable temperature Mössbauer spectroscopy. In both cases, the anionic moieties are isolated from each other and so no electrical conductivity is observed.
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- 2021
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18. A new Ni(dmit)2-based organic magnetic charge-transfer salt, (m-PO-CONH-N-methylpyridinium)[Ni(dmit)2]·CH3CN
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Soichi Ito, Tomofumi Kadoya, Shin'ichi Nakatsuji, Jun-ichi Yamada, Hiroki Akutsu, Scott S. Turner, and Yasuhiro Nakazawa
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chemistry.chemical_classification ,Spins ,010405 organic chemistry ,Radical ,Salt (chemistry) ,Crystal structure ,010402 general chemistry ,01 natural sciences ,Magnetic susceptibility ,0104 chemical sciences ,Inorganic Chemistry ,Crystallography ,chemistry ,Ferromagnetism ,Mean field theory ,Materials Chemistry ,Physical and Theoretical Chemistry ,Spin (physics) - Abstract
A new Ni(dmit)2-based organic magnetic charge-transfer (CT) salt, (m-PO-CONH-N-methylpyridinium)[Ni(dmit)2]·CH3CN, where PO = 2,2,5,5-Tetramethyl-3-pyrrolin-1-oxyl free radical and dmit = 2-Thioxo-1,3-dithiole-4,5-dithiolate, was obtained, the crystal structure and magnetic properties of which are reported. Magnetic susceptibility of the CT salt obeys a combination of 1D ferromagnetic (1DF) Heisenberg (J1DF = +0.26 K) and Singlet-Triplet (ST) models (JST = -51.2 K) with mean field (MF) approximation (JMF = -6.7 K), suggesting that spins on the PO radicals form 1D ferromagnetic chains and spins on the Ni(dmit)2 monoanions forms spin dimers at low temperature, the latter of which was also confirmed by band calculations.
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- 2018
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19. Bulk Kosterlitz–Thouless Type Molecular Superconductor β″-(BEDT-TTF)2[(H2O)(NH4)2Cr(C2O4)3]·18-crown-6
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Jordan R. Lopez, Lee Martin, Shusaku Imajo, Hiroki Akutsu, and Yasuhiro Nakazawa
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Superconductivity ,Superstructure ,18-Crown-6 ,02 engineering and technology ,Crystal structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Magnetic field ,Ion ,Inorganic Chemistry ,chemistry.chemical_compound ,Crystallography ,chemistry ,Molecule ,Physical and Theoretical Chemistry ,0210 nano-technology ,Critical field - Abstract
A new molecular superconductor, β”-(BEDTTTF)2[(H2O)(NH4)2Cr(C2O4)3].18-crown-6, has been synthesized from the organic donor molecule BEDT-TTF with the anion Cr(C2O4)3 3- . The crystal structure consists of conducting organic layers of BEDT-TTF molecules which adopt the β” packing motif (layer A), layers of NH4 + and Λ-Cr(C2O4)3 3- (layer B), layers of (H2O)(NH4)18- crown-6 (layer C), and layers of NH4 + and Δ-Cr(C2O4)3 3- (layer D) which produce a superstructure with a repeating pattern of ABCDABCDA. As a result of this packing arrangement this is the 2D superconductor with the widest gap between conducting layers where only a single donor packing motif is present (β”). Superconducting critical temperatures at ambient pressure observed by electrical transport and magnetic measurements are 4.0- 4.9 and 2.5 K, respectively. The strong 2D nature of this system, the broad transition to Tzero at 1.8K, and the transition of α of V ∝ Iα from 1 to 3 on I-V curves strongly suggests that the superconducting transition is very close to a Kosterlitz-Thouless transition. The magnetic field dependence of the superconducting critical temperature parallel to the conducting plane gives an upper critical field μ0Hc2// > 8 T, which is over the calculated Pauli-Clogston limit for this material.
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- 2017
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20. Anion polarity-induced self-doping in a purely organic paramagnetic conductor, α′-α′-(BEDT-TTF) 2 (PO-CONH- m -C 6 H 4 SO 3 )·H 2 O where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene and PO is the radical 2,2,5,5-Tetramethyl-3-pyrrolin-1-oxyl
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Shin'ichi Nakatsuji, Soich Ito, Scott S. Turner, Yasuhiro Nakazawa, Keita Ishihara, Jun-ichi Yamada, Hiroki Akutsu, and Fumiyoshi Nishiyama
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Stereochemistry ,Doping ,Fermi level ,02 engineering and technology ,Crystal structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Magnetic susceptibility ,0104 chemical sciences ,Ion ,Inorganic Chemistry ,Dipole ,Paramagnetism ,chemistry.chemical_compound ,Crystallography ,symbols.namesake ,chemistry ,Materials Chemistry ,symbols ,Physical and Theoretical Chemistry ,0210 nano-technology ,Tetrathiafulvalene - Abstract
A new BEDT-TTF-based salt with an organic free radical, α′-α′-(BEDT-TTF)2(PO-CONH-m-C6H4SO3)·H2O, has been prepared. The crystal structure consists of alternating donor and anion/water layers propagated along the c axis. The anisotropic radical anions form a head-to-head arrangement, which provides a permanent dipole moment. The effect on the nearest donor layer has been estimated to be 4.0 V. The salt has two crystallographically independent donor layers (A and B), one of which (A) is surrounded by the negative ends of the anion layer dipole whereas the B layers are bordered by the positive ends of the dipole. This structural feature suggests that layers A and B have different Fermi levels. To eliminate the imbalance, self-doping occurs whereby electron density is transferred from layer A to B. The temperature dependence of the magnetic susceptibility has 11.1% of extra Curie spins, from which a doping ratio of 12.7% has been estimated.
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- 2017
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21. Enantiopure and racemic radical-cation salts of bis(2′-hydroxylpropylthio)(ethylenedithio)TTF with polyiodide anions
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Anthony Christian, Shin'ichi Nakatsuji, Milena A. Guziak, Hiroki Akutsu, Peter Maksymiw, Lee Martin, John D. Wallis, Jun-ichi Yamada, and Florence Konalian-Kempf
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Stereochemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Polyiodide ,Crystallography ,Enantiopure drug ,chemistry ,Radical ion ,Side chain ,Molecule ,Triiodide ,Enantiomer ,0210 nano-technology ,Tetrathiafulvalene - Abstract
The chiral TTF-based donor molecule bis(2′-hydroxylpropylthio)(ethylenedithio)tetrathiafulvalene (BHPT-EDT-TTF) has produced enantiopure R,R and S,S radical-cation salts with polyiodide anions I3− and I82−. Enantiomorphic 6 : 6 donor : I3 phases grown from either the R,R or S,S donor are semiconducting with similar activation energies of 0.24–0.30 eV and 0.22–0.23 eV, respectively, and contain three unique face-to-face donor pairs whose relative orientation is determined by side chain conformations and hydrogen bonding. Racemic material under the same conditions gave an insulating centrosymmetric phase with R,R and S,S donor cations in a face-to-face pair partnered with an octaiodide dianion, and with a ca. 3 : 1 disorder between the enantiomers. Enantiopure BHPT-EDT-TTF yielded two further insulating crystalline phases of composition 2 : 2 with triiodide and 2 : 1 with octaiodide.
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- 2017
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22. Above room temperature spin crossover in thioamide-functionalised 2,6-bis(pyrazol-1-yl)pyridine iron(ii) complexes
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Max Attwood, Scott S. Turner, Hiroki Akutsu, Lee Martin, and Dyanne L. Cruickshank
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Inorganic Chemistry ,chemistry.chemical_classification ,chemistry.chemical_compound ,Crystallography ,Differential scanning calorimetry ,chemistry ,Spin states ,Spin crossover ,Pyridine ,Cooperativity ,Crystal structure ,Single crystal ,Thioamide - Abstract
This work describes the synthesis of two novel functionalised 2,6-bis(pyrazol-1-yl)pyridine (bpp) ligands, namely 2,6-bis(pyrazol-1-yl)pyridine-4-carbothioamide (bppCSNH2) and N-methyl-2,6-bis(pyrazol-1-yl)pyridine-4-carbothioamide (bppCSNHMe). The corresponding solvated or non-solvated Fe(II) salts, [Fe(bppCSNH2)2]X2 and [Fe(bppCSNHMe)2]X2 (X = BF4− or ClO4−) were synthesised and their properties measured by SQUID magnetometry, Evans NMR, differential scanning calorimetry and single crystal X-ray diffraction. In the solid state [Fe(bppCSNH2)2]2+ salts persist in the low spin state below 350 K. The structure of [Fe(bppCSNH2)2](BF4)2·2MeNO2 shows a network of intermolecular interactions responsible for the low spin state stabilisation, relative to the prototypical [Fe(bpp)2]2+ spin crossover (SCO) salts. By contrast the complexes of bppCSNHMe both display abrupt SCO above 300 K. [Fe(bppCSNHMe)2](BF4)2·MeNO2 requires solvent loss before SCO can be observed centred at 332 K. The non-solvated [Fe(bppCSNHMe)2](ClO4)2 shows SCO centred at 325 K. Analysis of solvated and non-solvated crystal structures suggests that cooperativity is facilitated by thioamide-group interactions with neighbouring pyrazolyl and pyridyl moieties.
- Published
- 2019
23. 2D Molecular Superconductor to Insulator Transition in the β′′- (BEDT-TTF)2[(H2O)(NH4)2M(C2O4)3]·18-crown‑6 Series (M = Rh, Cr, Ru, Ir)
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Enric Canadell, Toby J. Blundell, Hiroki Akutsu, Jordan R. Lopez, Lee Martin, Alexander L. Morritt, Yasuhiro Nakazawa, Shusaku Imajo, Japan Society for the Promotion of Science, Royal Society (UK), Ministerio de Ciencia, Innovación y Universidades (España), and Generalitat de Catalunya
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Inorganic Chemistry ,Superconductivity ,chemistry.chemical_compound ,Crystallography ,chemistry ,Series (mathematics) ,010405 organic chemistry ,18-Crown-6 ,Physical and Theoretical Chemistry ,Insulator (genetics) ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences - Abstract
The series of salts β′′-(BEDT-TTF)2[(H2O)(NH4)2M(C2O4)3]·18-crown-6 show ambient-pressure superconductivity when M = Cr, Rh. Evidence indicates that the previously reported Cr and Rh salts show a bulk Berezinski–Kosterlitz–Thouless superconducting transition. The isostructural ruthenium and iridium salts are reported here. The Ir salt represents the first radical-cation salt to contain a 5d tris(oxalato)metalate anion. The Ru and Ir salts do not show superconductivity but instead undergo a broad chemically induced metal to insulator transition at 155 K for ruthenium and at 100 K for iridium. The c axes of the Ru and Ir salts are much shorter than those of the Rh and Cr salts. Thus, the more stable metallic state of the Cr and Rh salts is associated with the more strongly 2D electronic systems. The different low-temperature behavior of the Ru and Ir salts, which exhibit a smaller interlayer spacing, could originate from a structural change in the anionic layer which thus can be easily transmitted to the donor layers and generate a localized state. However, another possibility is that it originates from Berezinski–Kosterlitz–Thouless effects., This work has been supported by a Royal Society Leverhulme Trust Senior Research Fellowship, and the JSPS (KAKENHI Grant Number JP17H01144) and Royal Society (Research Grants (RG100853 and RG081209), International Exchange Scheme (IE130367 and IE150152), and International Joint Project (JP0869972)). L.M. thanks the Royal Society and Leverhulme Trust for a Senior Research Fellowship. J.R.L. and L.M. thank Nottingham Trent University for Ph.D. funding. E.C. acknowledges support by the MICIU (Spain) through Grant PGC2018-096955-BC44 and the Severo Ochoa Centers of Excellence Program (Grant SEV-2015-0496) as well as by the Generalitat de Catalunya (2017SGR1506).
- Published
- 2019
24. New Family of Six Stable Metals with a Nearly Isotropic Triangular Lattice of Organic Radical Cations and Diluted Paramagnetic System of Anions: κ(κ⊥)-(BDH-TTP)4MX4·Solv, where M = CoII, MnII; X = Cl, Br, and Solv = (H2O)5, (CH2X2)
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A. A. Bardin, Jun-ichi Yamada, and Hiroki Akutsu
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Chemistry ,Isotropy ,Inorganic chemistry ,02 engineering and technology ,General Chemistry ,Electronic structure ,Crystal structure ,Conductivity ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Ion ,Paramagnetism ,Crystallography ,General Materials Science ,Hexagonal lattice ,Isostructural ,0210 nano-technology - Abstract
A new family of six paramagnetic metals, namely, κ-(BDH-TTP)4CoCl4·(H2O)5 (I), κ-(BDH-TTP)4Co0.54Mn0.46Cl4·(H2O)5 (II), κ-(BDH-TTP)4MnCl4·(H2O)5 (III), κ⊥-(BDH-TTP)4CoBr4·(CH2Cl2) (IV), κ⊥-(BDH-TTP)4MnBr4·(CH2Cl2) (V), and κ⊥-(BDH-TTP)4MnBr4·(CH2Br2) (VI), has been synthesized and characterized by X-ray crystallography, four-probe conductivity measurements, SQUID magnetometry, and calculations of electronic structure. The newly discovered κ⊥-type packing motif of organic layers differs from the parent κ-type by a series of longitudinal shifts of BDH-TTP radical cations in the crystal structure. Salts I–VI form two isostructural groups: I–III (κ) and IV–VI (κ⊥). Salts I–III are isostructural to the previously discovered κ-(BDH-TTP)2FeIIIX4 (X = Cl, Br) even though the charge of FeX4– anions is half that of the MX42– (M = Co, Mn) anions. The tetrahedral anions are disordered in I–III but completely ordered in IV–VI. The type of included solvent molecule is solely determined by the anion size. The paramagnet...
- Published
- 2016
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25. Variation of Electronic Heat Capacity of κ-(BEDT-TTF)2Cu[N(CN)2]Br Induced by Partial Substitution of Donor Layers
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Emre Yesil, Hiroki Akutsu, Tetsuya Nomoto, Yasuhiro Nakazawa, Shusaku Imajo, and Satoshi Yamashita
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Crystallography ,Materials science ,Organic superconductor ,General Physics and Astronomy ,Molecule ,Partial substitution ,Heat capacity - Abstract
Low temperature thermodynamic properties of an organic superconductor κ-[(BEDT-TTF)0.95(BEDSe-TTF)0.05]2Cu[N(CN)2]Br where 5% of donor molecules of κ-(BEDT-TTF)2Cu[N(CN)2]Br are substituted by BEDS...
- Published
- 2020
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26. Structure and properties of a BEDT-TTF-based organic conductor with a ferrocene-based magnetic anion octamethylferrocenedisulfonate
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Shin'ichi Nakatsuji, Yasuhiro Nakazawa, Jun-ichi Yamada, Scott S. Turner, Hiroki Akutsu, and Ryuichiro Hashimoto
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chemistry.chemical_classification ,Spins ,Chemistry ,business.industry ,Salt (chemistry) ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Ion ,Conductor ,Inorganic Chemistry ,chemistry.chemical_compound ,Crystallography ,Semiconductor ,Ferrocene ,0210 nano-technology ,business ,Tetrathiafulvalene - Abstract
The structure and properties of a new semiconducting BEDT-TTF-based charge-transfer salt containing the magnetic monoanion octamethylferrocenedisulfonate (–O3SC5( CH3)4Fe+C5(CH3)4-SO3 – (ofds)), -(BEDT-TTF)5(ofds)2 is described (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene). The salt is a semiconductor with RT = 5.6 103 ·cm and Ea = 0.11 eV. There are two types of spins not only on the ferrocenyl parts but also the 2D donor layers. The former and latter spins obey Curie-Weiss (C = 0.721 emu K mol-1and = -5.5 K) and 2D Heisenberg (J2DH = - 80.3 K) models, respectively.
- Published
- 2018
27. Radical-cation salt with novel BEDT-TTF packing motif containing tris(oxalato)germanate(IV)
- Author
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Jordan R. Lopez, Hiroki Akutsu, and Lee Martin
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Tris ,Materials science ,Mechanical Engineering ,Inorganic chemistry ,Metals and Alloys ,Crystal structure ,Activation energy ,Conductivity ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Ion ,Crystallography ,chemistry.chemical_compound ,Radical ion ,chemistry ,Mechanics of Materials ,Electrical resistivity and conductivity ,Materials Chemistry ,Germanate - Abstract
The synthesis, crystal structure and resistivity of a new semiconducting BEDT-TTF radical-cation salt containing the tris(oxalato)germanate(IV) anion is reported. BEDT-TTF 4 [Ge(C 2 O 4 ) 3 ].0.5dichloromethane crystallizes in the space group P 2 1 / c, a = 18.322(7), b = 11.919(4), c = 32.746(11) A, β = 105.797(5)°, V = 6881(4) A 3 , T = 295(1) K, Z = 4. Electrical resistivity measurements show that BEDT-TTF 4 [Ge(C 2 O 4 ) 3 ].0.5dichloromethane is a semiconductor with an activation energy of 0.224 eV and room temperature resistivity of 212 Ω cm.
- Published
- 2015
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28. Structures and properties of diradical compounds containing disulfide and nitroxide groups
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Hiroki Akutsu, Kouki Fujikura, Shin'ichi Nakatsuji, Masaharu Satoh, and Jun-ichi Yamada
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Nitroxide mediated radical polymerization ,Chemistry ,Diradical ,Mechanical Engineering ,Inorganic chemistry ,Metals and Alloys ,Disulfide bond ,Charge density ,Crystal structure ,Condensed Matter Physics ,Nitroxide radical ,Redox ,Electronic, Optical and Magnetic Materials ,Crystallography ,Mechanics of Materials ,Materials Chemistry ,Cyclic voltammetry - Abstract
In order to develop a kind of dual redox system with rechargeable battery property having potential high charge density, eight disulfide compounds carrying nitroxide radical have been prepared. Reflecting their multi-redox nature observed in their cyclic voltammetry data, they exhibit multi-step charge–discharge profiles with fairly large capacities over 200 Ah kg−1 for the first discharging processes. The Curie–Weiss type behaviors or 1D Heisenberg type profiles found for the respective radical compounds could be understandable by investigating the clarified crystal structures of four compounds (3, 4, 7, and 8) among them.
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- 2015
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29. Molecular conductors from bis(ethylenedithio)tetrathiafulvalene with tris(oxalato)rhodate
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Yanjun Guo, Yoshihiko Ihara, Bin Zhang, Jordan R. Lopez, Yasuhiro Nakazawa, Yan Zhang, Shusaku Imajo, Hiroki Akutsu, Lee Martin, and Alexander L. Morritt
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Inorganic chemistry ,Fluorobenzene ,02 engineering and technology ,Crystal structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Crystallography ,symbols.namesake ,Benzonitrile ,chemistry ,Bromobenzene ,Chlorobenzene ,Electrical resistivity and conductivity ,symbols ,0210 nano-technology ,Raman spectroscopy ,Tetrathiafulvalene - Abstract
This article reports a family of new radical-cation salts of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with tris(oxalato)rhodate: three salts with the formula β′′-(BEDT-TTF)4[(cation)Rh(C2O4)3]·solvent (solvent = fluorobenzene, chlorobenzene, or bromobenzene) and one with the formula pseudo-κ-(BEDT-TTF)4[(NH4)Rh(C2O4)3]·benzonitrile. We report here the syntheses, crystal structures, electrical properties and Raman spectroscopy of these new molecular conductors. The bromobenzene salt shows a decrease in resistivity below 2.5 K indicative of a superconducting transition and a Shubnikov–de Haas oscillation with a frequency of 232 T and effective mass m* of 1.27me.
- Published
- 2017
30. Ambient-pressure molecular superconductor with a superlattice containing layers of tris(oxalato)rhodate enantiomers and 18-crown-6
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Hiroki Akutsu, Alexander L. Morritt, Jordan R. Lopez, Yoshihiko Ihara, Lee Martin, Shusaku Imajo, and Yasuhiro Nakazawa
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Tris ,Superconductivity ,Condensed matter physics ,Superlattice ,18-Crown-6 ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Magnetic susceptibility ,0104 chemical sciences ,Ion ,Inorganic Chemistry ,chemistry.chemical_compound ,Crystallography ,chemistry ,Physical and Theoretical Chemistry ,0210 nano-technology ,Hybrid material ,Ambient pressure - Abstract
We report a novel multilayered organic–inorganic hybrid material, β″-(BEDT-TTF)2[(H2O)(NH4)2Rh(C2O4)3]·18-crown-6. This is the first molecular superconductor to have a superlattice with layers of both BEDT-TTF and 18-crown-6 and also the first with the anion tris(oxalato)rhodate. This is the 2D superconductor with the widest gap between conducting layers, where only a single donor packing motif is observed (β″). The strong 2D nature of this system strongly suggests that the superconducting transition is a Kosterlitz–Thouless transition. A superconducting Tc of 2.7 K at ambient pressure was found by transport measurements and 2.5 K by magnetic susceptibility measurements.
- Published
- 2017
31. Stereoisomeric semiconducting radical cation salts of chiral bis(2-hydroxypropylthio)ethylenedithioTTF with tetrafluoroborate anions
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John D. Wallis, Hiroki Akutsu, Lee Martin, Shin'ichi Nakatsuji, Jordan R. Lopez, Jun-ichi Yamada, Milena A. Guziak, and Jack Oxspring
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chemistry.chemical_classification ,Tetrafluoroborate ,Chemistry ,Stereochemistry ,Salt (chemistry) ,General Chemistry ,Crystal structure ,Condensed Matter Physics ,chemistry.chemical_compound ,Crystallography ,Enantiopure drug ,Radical ion ,General Materials Science ,Orthorhombic crystal system ,Isostructural ,Monoclinic crystal system - Abstract
The new chiral TTF-based donor molecule bis(2-hydroxypropylthio)ethylenedithiotetrathiafulvalene has produced enantiopure R,R and S,S radical cation salts with the tetrafluoroborate anion as well as the nearly isostructural meso/racemate mixture. The enantiopure R,R or S,S salts are both 1:1 semiconducting salts with activation energies of 0.19–0.24 eV, both crystallising in the orthorhombic space group C2221. The semiconducting salt containing both meso and racemic donor cations has a very similar crystal structure but crystallising in the monoclinic space group C2/c (β = 91.39°) with similar S⋯S interactions but a smaller activation energy of 0.15–0.17 eV. This is in contrast to previous families of this type where the disordered racemate has a larger activation energy than its enantiopure salts.
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- 2014
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32. A strongly polarized organic conductor
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Hiroki Akutsu, Jun-ichi Yamada, Keita Ishihara, Yasuhiro Nakazawa, Scott S. Turner, and Shin'ichi Nakatsuji
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chemistry.chemical_classification ,Materials science ,Salt (chemistry) ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Ion ,Conductor ,Crystal ,Crystallography ,Dipole ,chemistry ,Group (periodic table) ,Moment (physics) ,General Materials Science ,Polar space ,0210 nano-technology - Abstract
The electrically conducting salt α-(BEDT-TTF)2(PO-CON(CH3)CH2SO3)·3H2O crystallized in the polar space group, Pna21. 2D conducting BEDT-TTF layers and anion layers alternate along the crystallographic c axis. In the crystal, permanent dipoles of all anions point along the c axis, providing a net crystal dipole moment.
- Published
- 2016
33. A new BEDT-TTF-based organic metal with an anionic weak acceptor 2-sulfo-1,4-benzoquinone
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Shin'ichi Nakatsuji, Jun-ichi Yamada, Scott S. Turner, Hiroki Akutsu, and Yuka Maruyama
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chemistry.chemical_classification ,education.field_of_study ,Chemistry ,Mechanical Engineering ,Inorganic chemistry ,Population ,Metals and Alloys ,Salt (chemistry) ,Electron acceptor ,Condensed Matter Physics ,Acceptor ,Electronic, Optical and Magnetic Materials ,1,4-Benzoquinone ,Metal ,Crystallography ,chemistry.chemical_compound ,Mechanics of Materials ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,education ,Single crystal ,Tetrathiafulvalene - Abstract
An anionic weak acceptor, 2-sulfo-1,4-benzoquinone, has provided a new BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) salt (BEDT-TTF)2(2-sulfo-1,4-benzoquinone)·H2O. Single crystal X-ray analysis indicates that the unit cell has two crystallographically independent donor layers, one of which has a β″-type packing motif and the other being disordered. Population analysis and SQUID magnetometry suggests that non-β″-layer has an α‴-type packing motif. The dual-layered salt shows metallic behavior with a metal–insulator transition at 90 K.
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- 2011
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34. BEDT-TTF Tris(oxalato)germanate(IV) Salts with Novel Donor Packing Motifs
- Author
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Hiroki Akutsu, Peter N. Horton, Peter Day, Shin'ichi Nakatsuji, Jun-ichi Yamada, and Lee Martin
- Subjects
Crystal ,Tris ,Crystallography ,chemistry.chemical_compound ,Chemistry ,Inorganic chemistry ,Germanate ,General Chemistry ,Crystal structure - Abstract
The synthesis, crystal structure, and conducting properties of two new BEDT-TTF charge-transfer salts containing tris(oxalato)germanate(IV) anions are described. (BEDT-TTF)5[Ge(C2O4)3]2 (1) crystal...
- Published
- 2010
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35. New radical salts based on TEMPO-substituted 2,4,6-triphenylpyridinium and transition metal complexes
- Author
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Hiroki Akutsu, Keishi Ohara, Shin'ichi Nakatsuji, Bilkish Rahman, and Jun-ichi Yamada
- Subjects
chemistry.chemical_classification ,Tetrafluoroborate ,Curie–Weiss law ,Heisenberg model ,Mechanical Engineering ,Inorganic chemistry ,Metals and Alloys ,Salt (chemistry) ,Crystal structure ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Crystallography ,chemistry ,Transition metal ,Mechanics of Materials ,Materials Chemistry ,Antiferromagnetism ,Pyridinium - Abstract
Series of radical salts derived from a 2,4,6-triphenylpyridinium (TPP) carrying TEMPO-substituent and transition metal complexes were prepared by the anion exchange of the TPP–TEMPO tetrafluoroborate with [n-Bu4N][Ni(dmit)2], [n-Bu4N]2[Pd(dmit)2], [n-Bu4N]2[Pt(dmit)2], [n-Bu4N][Ni(mnt)2], or [n-Bu4N]2[Ni(mnt)2] to give crystals with different structural features. While weak antiferromagnetic interactions of the Curie–Weiss behavior of S = 1/2 spin are predominantly observed in the salts of Pd(dmit)2, Pt(dmit)2 and Ni(mnt)2, the magnetic behavior of 1:1 Ni(dmit)2 salt can be explained by the additional contribution from the spins on Ni(dmit)2 anions (χ − χTEMPO), obeying the 2D Heisenberg model. A couple of the oxidized salts, [TPP][Ni(dmit)2] as well as [TPP]2[Pd(dmit)2], exhibit semi-conducting properties with relatively high room temperature conductivities.
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- 2009
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36. Structures and magnetic properties of Mn(hfac)2 complexes derived from Bis-TEMPO-substituted diamines
- Author
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Jun-ichi Yamada, Shin'ichi Nakatsuji, Hidetoshi Kinoshita, and Hiroki Akutsu
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Stereochemistry ,Intermolecular force ,Spin system ,chemistry.chemical_element ,Ethylenediamine ,Manganese ,Inorganic Chemistry ,Metal ,chemistry.chemical_compound ,Crystallography ,chemistry ,visual_art ,Atom ,Materials Chemistry ,visual_art.visual_art_medium ,Antiferromagnetism ,Physical and Theoretical Chemistry ,Spin (physics) - Abstract
Structures and properties of three Mn(hfac)2 (hfac = hexafluoroacetylacetonate) complexes derived from two kinds of bis-TEMPO (2,2,6,6-tetramethylpiperdinyl-1-oxy)-substituted diamines are reported. In a complex derived from bis-TEMPO-substituted ethylenediamine, the unit is coordinated to the manganese atom to afford a spin system with weak antiferromagnetic intermolecular interactions, while apparent ligations of both TEMPO groups to the metal atom are observed in a couple of Mn(hfac)2 complexes derived from bis-TEMPO-substituted piperadine to result in spin systems with fairly large antiferromagnetic interactions.
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- 2008
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37. Molecular Complexes Based on Tetrathiafulvalene and Dialkylviologens
- Author
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Hiroki Akutsu, Shin'ichi Nakatsuji, Bilkish Rahman, and Jun-ichi Yamada
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Models, Molecular ,crystal structure ,Solid-state chemistry ,Catenane ,Molecular Conformation ,Supramolecular chemistry ,Pharmaceutical Science ,Crystal structure ,Crystallography, X-Ray ,Photochemistry ,Viologens ,Analytical Chemistry ,lcsh:QD241-441 ,chemistry.chemical_compound ,symbols.namesake ,lcsh:Organic chemistry ,Heterocyclic Compounds ,Drug Discovery ,medicine ,Physical and Theoretical Chemistry ,Alkyl ,chemistry.chemical_classification ,Molecular Structure ,Full Paper ,viologen ,Chemistry ,Organic Chemistry ,Hydrogen Bonding ,Viologen ,Crystallography ,Models, Chemical ,Chemistry (miscellaneous) ,symbols ,Molecular Medicine ,Indicators and Reagents ,TTF ,van der Waals force ,Crystallization ,Molecular complex ,Tetrathiafulvalene ,CT complex ,medicine.drug - Abstract
Three kinds of molecular complexes based on tetrathiafulvalene (TTF) and dialkylviologens were prepared and their crystal structures elucidated. While TTF-dimethylviologen complex forms a mixed stack arrangement of donors and acceptors in its crystal structure, TTF donors aggregate with long alkyl groups by CH/π and/or van der Waals interactions in a couple of TTF-heptylviologen complexes. Keywords: Molecular complex; CT complex; TTF; viologen; crystal structure Introduction Considerable attention has recently been paid in the field of supramolecular and materials chemistry to the incorporation of electroactive components into supramolecular assemblies. Among them, the supramolecular and macrocyclic assemblies derived from redox-controllable TTF 1 and dialkyl-4,4’-bipyridinium dications (dialkylviologens) such as 2 , have evoked attention, not only as catenanes and rotaxanes, but also as molecular switche s and potential molecular el ectronics devices [1]. The assembly of such kinds of molecular complexes relies strongly upon non-covalent charge-transfer (CT) interactions between donors and acceptors [2]. Since a dialkylviolgen
- Published
- 2007
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38. Organic biradical compounds with a mesogenic core and long alkoxy groups: preparation, structures and magnetic properties
- Author
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Takamitsu Amano, Jun-ichi Yamada, Shin'ichi Nakatsuji, and Hiroki Akutsu
- Subjects
Biphenyl ,Stereochemistry ,Radical ,Mesogen ,Organic Chemistry ,Crystal structure ,chemistry.chemical_compound ,Crystallography ,Azobenzene ,chemistry ,Alkoxy group ,Antiferromagnetism ,Physical and Theoretical Chemistry ,Naphthalene - Abstract
Series of organic biradical compounds 3a–3h consisting of a mesogenic core (biphenyl, naphthalene, azobenzene and azoxybenzene) and long alkoxy groups with PROXYL or TEMPO radicals were prepared. The TEMPO derivatives (3b, 3d, 3f, and 3h) were found to show fairly large antiferromagnetic interactions (J = −34 ∼ −45 K) being well expressed by singlet-triplet model irrespective of the mesogenic cores and the behavior is understandable by taking a hand-in-hand like assembled structure into consideration. On the other hand, only weak antiferromagnetic interactions with Curie–Weiss behavior were observed in all of the PROXYL derivatives (3a, 3c, 3e, and 3d) affording a sharp contrast with the TEMPO-based biradicals. Copyright © 2006 John Wiley & Sons, Ltd.
- Published
- 2006
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39. New organic free radical anions and their TTF and/or BEDT-TTF salts
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Hiroki Akutsu, Kenji Mori, Jun-ichi Yamada, Shin'ichi Nakatsuji, and Kazuyoshi Masaki
- Subjects
Inorganic Chemistry ,chemistry.chemical_classification ,Crystallography ,chemistry ,X-ray crystallography ,Inorganic chemistry ,Materials Chemistry ,Salt (chemistry) ,Crystal structure ,Physical and Theoretical Chemistry ,Metathesis - Abstract
We have prepared eight TEMPO-containing anions TEMPO – A – CO – ( n - ) C 6 H 4 S O 3 - (n = o, m, p for A = NH (N1, N2, N3), n = o, p for A = NCH3 (M1, M3), and n = o, m, p for A = O (O1, O2, O3)) as PPh4 salts. Metathesis of their salts with (TTF)3(BF4)2 gave their TTF salts. Electrocrystallization of BEDT-TTF with PPh4 · M1 yielded the α-(BEDT-TTF)3(M1)2 · 8H2O salt. We report their crystal structures, electrical resistivities, and magnetic properties. The relation between crystal structures and physical properties are discussed.
- Published
- 2005
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40. New organic magnetic anions (n=0–3 for A=H, n=2 for A=CH3) and their TTF, TMTSF, and/or BEDT-TTF salts
- Author
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Jun-ichi Yamada, Shin'ichi Nakatsuji, Hiroki Akutsu, and Akiko Yamashita
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Inorganic Chemistry ,chemistry.chemical_classification ,Crystallography ,chemistry ,X-ray crystallography ,Materials Chemistry ,Salt (chemistry) ,Organic chemistry ,Crystal structure ,Physical and Theoretical Chemistry - Abstract
Five TEMPO-containing anions TEMPO - CONA ( CH 2 ) n SO 3 - (H0−, A = H, n = 0; H1−, A = H, n = 1; H2−, A = H, n = 2; H3−, A = H, n = 3; M2−, A = CH3, n = 2) have been prepared as PPh4 salts. So far three TTF salts ((TTF)(H1) · 2H2O, (TTF)(H2) · H2O, and (TTF)(M2) · 0.50H2O), one TMTSF salt ((TMTSF)(H1) · 2H2O · PhCl), and one BEDT-TTF salt (α-(BEDT-TTF)5(H1)2 · 6H2O) have been obtained. Their crystal structures, electrical resistivities, and magnetic properties are reported.
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- 2005
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41. New Organic Functional Anions: Ferrocenyl-(CONHCH2SO3−)n (n = 1–2) and their TTF Salts
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Hiroki Akutsu, Jun-ichi Yamada, Shin'ichi Nakatsuji, and Keigo Furuta
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Magnetic measurements ,Curie–Weiss law ,Magnetic moment ,Condensed matter physics ,Chemistry ,Mechanical Engineering ,Dimer ,Metals and Alloys ,Condensed Matter Physics ,Redox ,Electronic, Optical and Magnetic Materials ,Crystallography ,chemistry.chemical_compound ,Mechanics of Materials ,Materials Chemistry ,Antiferromagnetism ,Ferrocenyl group - Abstract
New organic functional anions that includes the ferrocenyl group, CpFeCp-CONHCH 2 SO 3 − and Fe(Cp-CONHCH 2 SO 3 − ) 2 , are prepared as tetraphenylphosphonium (PPh4) salts. They reacted with (TTF) 3 (BF 4 ) 2 to give TTF monocation salts. The X-ray analyses indicate that for all salts TTF forms a dimer which is separated by the relatively larger anions. The oxidation reaction of (PPh 4 )(CpFeCp-CONHCH 2 SO 3 ) with I 2 gave the Zwitter-ion, CpFe + Cp-CONHCH 2 SO 3 − , which shows a Curie-Weiss behavior ( C = 0.800 emu·K/mol, θ = −1.13 K) with weak antiferromagnetic interaction. This magnetic moment is found to be attributed to the ferrocenyl radical.
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- 2005
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42. Novel organic magnetic conductors based on organochalcogen donors and an organic magnetic anion, TEMPO-NHCOCH2SO3−
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Jun-ichi Yamada, Hiroki Akutsu, and Shin'ichi Nakatsuji
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chemistry.chemical_classification ,Curie–Weiss law ,Condensed matter physics ,biology ,Heisenberg model ,Mechanical Engineering ,Metals and Alloys ,Salt (chemistry) ,Electrolyte ,Crystal structure ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Crystallography ,chemistry ,Mechanics of Materials ,Electrical resistivity and conductivity ,Materials Chemistry ,biology.protein ,Tetrathiafulvalene ,Organic anion - Abstract
We report here four novel purely organic magnetic conductors containing common electron donors together with an organic anion including an organic free radical, (TTF)(TEMPO-NHCOCH 2 SO 3 )·0.5H 2 O ( 1 ), (TMTSF)(TEMPO-NHCOCH 2 SO 3 )·2H 2 O ( 2 ), (BEDT-TTF) 3 (TEMPO-NHCOCH 2 SO 3 ) 2 ·2H 2 O ( 3 ), and α-(BEDT-TTF) 3 (TEMPO-NHCOCH 2 SO 3 ) 2 ·6H 2 O ( 4 ). The TTF complex was prepared by metathesis of (TTF) 3 (BF 4 ) 2 and the PPh 4 salt of the anion ( 5 ). The other complexes were obtained by electrocrystallization of the corresponding donors with the salt 5 as an electrolyte. Crystal structures of 2–4 have been solved. The salts 1 and 2 show relatively high resistivities (>10 7 and 5 × 10 3 Ω·cm), whilst the BEDT-TTF salts 3 and 4 have rather low room temperature resistivities (1.2 and 5.1 Ω·cm) with small activation energies (0.041 and 0.050 eV). The magnetic behavior of complex 1 obeys the Curie-Weiss law ( C = 0.379 emu·K/mol and θ = −3.29 K) and those of the other complexes obey the 1-D Heisenberg model ( C / J = 0.366/−0.32 for 2 , 0.373/−0.81 for 3 , and 0.380 emu·K·mol −1 /+0.42 K for 4 ). The relationships between the crystal structures and the physical properties are discussed.
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- 2005
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43. Crystal structures and physical properties of new BDA-TTP conductors
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Hiroki Akutsu, Kazuya Fujimoto, Shin'ichi Nakatsuji, Koichi Kikuchi, Hiroyuki Nishikawa, and Jun-ichi Yamada
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Superconductivity ,Phase transition ,Condensed matter physics ,Chemistry ,Mechanical Engineering ,Metals and Alloys ,Crystal structure ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Crystallography ,Transition metal ,Mechanics of Materials ,Materials Chemistry ,Antiferromagnetism ,Isostructural ,Metal–insulator transition ,Néel temperature - Abstract
The TaF 6 and FeBr 4 salts of BDA-TTP [2,5-bis(1,3-dithian-2-ylidene)-l,3,4,6-tetrathiapentalene] have been prepared and characterized as β-(BDA-TIP) 2 TaF 6 and β-(BDA-TIP) 2 FeBr 4 , respectively. The crystal structure of β-(BDA-TTP) 2 TaF 6 is isostructural to those of the ambient-pressure superconductors β-(BDA-TTP) 2 X (X = SbF 6 , AsF 6 and PF 6 ), but this salt undergoes an Ml (metal-to-insulator) transition instead of a superconducting transition at ambient pressure. The β-(BDA-TTP) 2 FeBr 4 salt, which is isomorphous to the superconductors β-(BDA-TTP) 2 MCl 4 (M = Fe and Ga) under applied pressures, exhibits a phase transition near 170 K and antiferromagnetic ordering with the Neel temperature (T N ) of about 9.5 K at ambient pressure.
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- 2005
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44. Structures and Physical Properties of New β′-BEDT-TTF Tris-Oxalatometallate (III) Salts Containing Chlorobenzene and Halomethane Guest Molecules
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Hiroki Akutsu, Peter Day, A Akutsu-Sato, Mark E. Light, Akiko Kobayashi, D.A. Tocher, Takehiko Mori, Shin'ichi Nakatsuji, Jun-ichi Yamada, M.B. Hurstho, and Scott S. Turner
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Mechanical Engineering ,Inorganic chemistry ,Metals and Alloys ,Halomethane ,Conductivity ,Condensed Matter Physics ,Oxalate ,Electronic, Optical and Magnetic Materials ,Metal ,chemistry.chemical_compound ,Crystallography ,chemistry ,Mechanics of Materials ,Electrical resistivity and conductivity ,Chlorobenzene ,visual_art ,Pyridine ,Materials Chemistry ,visual_art.visual_art_medium ,Molecule - Abstract
We report the structures and physical properties of new β′-(BEDT-TTF)[Fe(oxalate)]·G salts where A = HO, G = PhCl; A = Rb G = Pyridine. The structure of the PhCl salt is isomorphous with β′-(BEDT-TTF)[(HO)M(oxalate)] with other guest molecules. PhCl is ordered in die hexagonal pockets formed by the [(HO)Fe(oxalate)] layer. The electrical conductivity is metallic down to 100 K, below which the resistivity increases with decreasing temperature. The specific conductivity at room temperature is about 10 S/cm. We also report the salt β′-(BEDT-TTF) [RbFe(oxalate)]·Pyridine where Rb replaces HO. The electrical resistivity shows metallic behavior down to 100 K. and turns up gradually to a maximum at 65 K below which the system re-enters the metallic state down to liquid helium temperature. Neither salt shows superconductivity down to 2 K. In addition, other new β′-(BEDT-TTF)[(HO)M(oxalate) ]·salts with M = Cr, Ga, Fe; G = CHCl , CHClBr, CHBr are also reported. © 2005 Elsevier B.V. All rights reserved.
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- 2005
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45. New Organic Conductors and Superconductors Based on Dihydro-TTF (DHTTF) Donors
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Isao Ikemoto, Jun-ichi Yamada, Koichi Kikuchi, Hiroki Akutsu, Shin'ichi Nakatsuji, Hiroyuki Nishikawa, and Reiji Hayashi
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Metal ,Superconductivity ,Crystallography ,Range (particle radiation) ,Materials science ,visual_art ,visual_art.visual_art_medium ,General Materials Science ,General Chemistry ,Crystal structure ,Condensed Matter Physics ,Electrical conductor - Abstract
The synthesis of dihydrotetrathiafulvalene (DHTTF) donors and the preparation of their charge-transfer (CT) salts have been undertaken to develop new organic metals and superconductors. The molecular structures of methylenedithio-DHTTF (MDHT), 1,4-dioxane-2,3-diyldithio-DHTTF (DODHT), and methylmethylidenedithio-DHTTF (Me-MDHT) are secured by X-ray crystallographic analyses. These DHTTF donors provide CT salts characterized by a wide range of conducting behavior from semiconducting to metallic and superconducting. The crystal structures of CT salts from each category are described.
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- 2005
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46. Thermotropic properties of ferrocene derivatives bearing a cholesteryl unit: structure-properties correlations
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Hiroki Akutsu, Dan Scutaru, Daniela Apreutesei, Shin’ichi Nakatsuji, Gabriela Lisa, and Nicolae Hurduc
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Steric effects ,Azo compound ,Chemistry ,Mesogen ,General Chemistry ,Thermotropic crystal ,Inorganic Chemistry ,chemistry.chemical_compound ,Crystallography ,Ferrocene ,Liquid crystal ,Organic chemistry ,Chirality (chemistry) ,Metallocene - Abstract
The synthesis and structural characterization of new liquid-crystalline compounds containing ferrocene, azo-aromatic and cholesteryl groups are reported. Taking into account the advantage brought by chirality, ferrocene and azo units, these structures could be good precursors for obtaining materials capable of responding to magnetic and electric fields or to UV-light exposure. The influence of each structural unit (ferrocene, cholesterol, azo aromatic core and flexible chain length) has been studied by comparing analogous compounds possessing the same structure but without the element being analyzed. Ferrocene is a three-dimensional bulky unit, so that, regardless of the substituents' nature, this unit could cause steric repulsions with neighboring molecules. These interactions could lead to a decrease of the transition temperature domain. Surprisingly, a decrease in the clearing point was not observed for the compounds discussed. This behavior was possible because ferrocene is connected to the mesogen via a flexible unit. As a consequence, both phenyl analogues and ferrocene derivatives presented liquid-crystalline properties with similarly high clearing points, but above the thermal stability of derivatives with azo groups. Their melting points depend on the way the molecules are packed, with different crystalline states being detected in the case of ferrocene derivatives. In order to explain the liquid-crystalline behavior of the compounds synthesized, molecular simulations were performed using the Hyperchem program. Copyright © 2005 John Wiley & Sons, Ltd.
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- 2005
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47. N-Salicylideneamine Derivatives with TEMPO Substituents
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Hiroki Akutsu, Jun-ichi Yamada, Masayuki Hata, and Shin'ichi Nakatsuji
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Models, Molecular ,crystal structure ,Radical ,Salicylideneamine ,Pharmaceutical Science ,salicylideneaniline ,Crystal structure ,Crystallography, X-Ray ,Photochemistry ,Article ,Analytical Chemistry ,Cyclic N-Oxides ,lcsh:QD241-441 ,Light responsive ,lcsh:Organic chemistry ,magnetic property ,Drug Discovery ,Antiferromagnetism ,Amines ,Physical and Theoretical Chemistry ,Schiff Bases ,Chemistry ,Organic Chemistry ,Intermolecular force ,Temperature ,Salicylates ,Crystallography ,Ferromagnetism ,Chemistry (miscellaneous) ,Molecular Medicine ,TEMPO - Abstract
Three N-salicylideneamine derivatives bearing TEMPO (2,2,6,6-tetra- methyl-1-piperidinyloxy) substituents were prepared in order to study their structure and property relationships and to investigate the possibilities of the existence of heat and/or light responsive magnetic properties. Curie-Weiss behavior with weak ferromagnetic intermolecular spin-spin interactions was observed in one of the radicals, while antiferromagnetic interactions were predominant for the other radicals and the structure-property relationships were investigated for the radical compounds from their crystal structures obtained by X-ray analyses. Preliminary results of the examination of their responses towards light and heat are also described.
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- 2004
48. Freezing of Crankshaft Motion of trans-Stilbene Molecule in Charge-Transfer Complexes, STB-TCNQ and STB-TCNQF4
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Hiroki Akutsu, Kazuya Saito, Mizuho Okada, Michio Sorai, and and Akane Sato
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Trans stilbene ,Charge (physics) ,Calorimetry ,Tetracyanoquinodimethane ,Acceptor ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Crystallography ,chemistry ,Materials Chemistry ,Molecule ,Physical and Theoretical Chemistry ,Adiabatic process ,Glass transition - Abstract
Heat capacities of crystalline charge-transfer (CT) complexes between trans-stilbene (STB) and tetracyanoquinodimethane (TCNQ) or (TCNQ)F4 were precisely measured below room temperature by adiabatic calorimetry. Although orientational disorder is seemingly absent, a glass transition due to freezing of the crankshaft motion is observed in STB-(TCNQ)F4 around 240 K as in the case of highly disordered STB-TCNQ around 250 K. Assessment of the degree of CT by IR and structural methods indicates that STB-(TCNQ)F4 is not a fully but weakly (only partially) ionic complex with a similar degree of CT of 0.1-0.2 to that in STB-TCNQ, despite the large difference in acceptor ability.
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- 2004
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49. Preparation and Magnetic Properties of Radical Anion Salts Derived from Styrylpyryliums and the Corresponding Photo-Dimers
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Shin'ichi Nakatsuji, Jun-ichi Yamada, Hiroki Akutsu, and Yuya Ogawa
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chemistry.chemical_classification ,Crystallography ,chemistry.chemical_compound ,Monomer ,Ferromagnetism ,Chemistry ,Heisenberg model ,Inorganic chemistry ,Salt (chemistry) ,Antiferromagnetism ,General Chemistry ,Crystal structure ,Ion - Abstract
The preparation and magnetic properties of organic radical anion salts derived from styrylpyrylium derivatives 1a and 2a are described and compared to those of the corresponding photo-dimers. The magnetic properties of the radical anions for TCNQ salt 1b and TCNQF4 salt 1c are rather different, showing antiferromagnetic interactions based on the 1-D Heisenberg model in the former, and ferromagnetic interactions in the latter. This difference is considered to be a result of the fairly large difference in their crystal structures. A considerable change in the magnetic properties was found between the radical anion salts of monomers and the corresponding photo-dimers, in which magnetic susceptibilities are largely diminished.
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- 2003
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50. Development of New Organic Metals and Superconductors from a Non-Ttf Donor System
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Hiroyuki Nishikawa, Hiroki Akutsu, Koichi Kikuchi, Takashi Toita, Isao Ikemoto, Shin'ichi Nakatsuji, Jun-ichi Yamada, and M. Watanabe
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Superconductivity ,Condensed matter physics ,General Chemistry ,Crystal structure ,Condensed Matter Physics ,Metal ,Paramagnetism ,chemistry.chemical_compound ,Crystallography ,chemistry ,visual_art ,visual_art.visual_art_medium ,Antiferromagnetism ,General Materials Science ,Metal–insulator transition ,Néel temperature ,Tetrathiafulvalene - Abstract
The study of three kinds of non-tetrathiafulvalene (TTF) donors, 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA), 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene (BDH), and 2-(1,3-dithiolan-2-ylidene)-5-(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (DHDA), which contain the bis-fused 1,3-dithiole-2-ylidene unit instead of the TTF unit as a π-electron system, has been undertaken to develop new molecular-based organic superconductors, magnetic conductors, and organic metals. The BDA donor produces the superconducting SbF 6 , AsF 6 , and PF 6 salts. The κ-(BDH) 2 FeCl 4 salt is a paramagnetic organic metal stable down to 1.5 K, whereas β-(BDA) 2 FeCl 4 exhibits metallic conducting behavior with a sharp metal-to-insulator (MI) transition (T MI = 113K), and antiferromagnetic ordering with a Neel temperature of near 8.5 K. Several salts of DHDA, a hybrid of BDA and BDH, are found to be metallic.
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- 2003
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