Update 1 of: Calorimetric Investigation of Phase Transitions Occurring in Molecule-Based Magnets

Sorai, Michio; Nakazawa, Yasuhiro; Nakano, Motohiro; Miyazaki, Yuji

doi:10.1021/cr300156s

Cited by 96 publications

(61 citation statements)

References 644 publications

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“…These thermodynamic parameters are typical for first order spin-transitions. 31 Notably, although its hysteresis is wider, the overall midpoint X-ray powder diffraction on 3[BF 4 ] 2 ·2MeNO 2 , that had been exposed to air, showed it to be poorly crystalline at 298 K which is consistent with solvent loss from the sample. The peaks in the powder pattern still showed a reasonable match with a simulation from the 200 K crystal structure, however.…”

Section: Resultsmentioning

confidence: 93%

Iron(II) Complexes of Tridentate Indazolylpyridine Ligands: Enhanced Spin-Crossover Hysteresis and Ligand-Based Fluorescence

et al. 2015

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ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. ABSTRACTReaction of 2,6-difluoropyridine with 2 equiv indazole and NaH at room temperature affords a mixture of 2,6-bis(indazol-1-yl)pyridine (1-bip), 2-(indazol-1-yl)-6-(indazol-2-yl)pyridine (1,2-bip) and 2,6-bis(indazol-2-yl)pyridine (2-bip), which can be separated by solvent extraction. A two-step procedure using the same conditions also affords both 2-(indazol-1-yl)-6-(pyrazol-1-yl)pyridine (1-ipp) and 2-(indazol-1-yl)-6-(pyrazol-2-yl)pyridine (2-ipp). These are all annelated analogues of 2,6-di(pyrazol-1-yl)pyridine, an important ligand for spin-crossover complexes.Iron (

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Section: Resultsmentioning

confidence: 93%

Iron(II) Complexes of Tridentate Indazolylpyridine Ligands: Enhanced Spin-Crossover Hysteresis and Ligand-Based Fluorescence

et al. 2015

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“…18 The magnetic properties are reported to be sensitive even under weak external magnetic fields by¯SR experiments for κ-(BEDT-TTF) 2 Cu 2 (CN) 3 . 31 The C p T ¹1 vs. T 2 plot of κ-(BEDT-TTF) 2 Cu 2 (CN) 3 shown in Figure 4a resembles the metallic organic charge-transfer complexes consisting of BEDT-TTF, TMTSF, or BETS, among others, whose details were recently reviewed in ref 4.…”

Section: ç Absence Of Magnetic Ordering and Gapless Excitations In Ormentioning

confidence: 89%

“…The heat capacity measurements can give information on changes in these microscopic degrees of freedom, and they are effective in detecting phase transitions and crossover features. 3,4 Moreover, thermodynamic measurements at low temperatures can clarify the nature of the ground states, since it is possible to extract spectroscopic information on the low-energy excitation spectrum from them. 5 Recently, an unusual liquid-like state of spins was observed in organic charge-transfer salts with triangle lattice structures.…”

Section: 2mentioning

confidence: 99%

“…9 Numerous insulating compounds which have AF-ordered ground states or chargeordered ground states show vanishing £. 4,5 The heat capacity data of κ-(BEDT-TTF) 2 2 ]Br, and β¤-(BEDT-TTF) 2 ICl 2 , typical Mott insulating compounds, are shown for reference in Figure 4a. They all show 3D AF ordering around 2030 K and superconductivity at lower temperatures under pressure.…”

Section: ç Absence Of Magnetic Ordering and Gapless Excitations In Ormentioning

confidence: 99%

“…The origin of the upturns was the nuclear Schottky contribution for κ-(BEDT-TTF) 2 Cu 2 (CN) 3 and rotational tunneling levels of methyl groups for [Pd(dmit) 2 ] compounds and should be considered separately from the present magnetic characteristics. The insensitivity to external magnetic fields is also a common feature of metallic compounds and is in fine contrast with usual paramagnetic materials with localized spin moments 4 and superconducting compounds. 5 The absence of magnetic field dependence in the temperature-linear term in heat capacity means that the excitation levels exist as a continuous spectrum, and the magnitude of £ is in proportion to the density of states of such an excitation spectrum.…”

Section: ç Absence Of Magnetic Ordering and Gapless Excitations In Ormentioning

confidence: 99%

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Thermodynamics of a Liquid-like Spin State in Molecule-based Magnets with Geometric Frustrations

Nakazawa

2013

Chemistry Letters

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We review novel thermodynamic properties of κ-(BEDT-TTF) 2 Cu 2 (CN) 3 and EtMe 3 Sb[Pd(dmit) 2 ] 2 , where BEDT-TTF stands for bisethylenedithiotetrathiafulvalene and dmit stands for 1,3-dithiole-2-thione-4,5-dithiolate unveiled via singlecrystal calorimetry. These compounds are organic dimer-based Mott insulators with a two-dimensional triangular lattice, where electron correlations produce localized radical spins on each molecular dimer. Néel-type magnetic orderings are prohibited by geometric frustrations and strong quantum mechanical fluctuations. The spin orientation of localized π electron fluctuates like a liquid even at zero energy, and the so-called spin-liquid (SL) ground state appears in them. We have performed heat capacity measurements down to extremely low temperatures and observed that the low-temperature heat capacities show a gapless character, evidenced by the finite electronic heat capacity coefficient, £. Although the chargetransport properties of these compounds are insulating, the thermodynamic parameters, which reflect the low-energy excitations from the liquid ground state, resemble those of typical metallic compounds with Fermi-liquid characteristics. The magnitude of the £ was scaled with the magnetic susceptibility extrapolated down to T = 0. The realization of the unusual magnetic state coupled with the charge degree of freedom is suggested by several other experiments in addition to the heat capacity measurements. Herein we review thermodynamic discussions based on the experiments reported up to now to clarify the novelty of this magnetic ground state. Ç IntroductionThermodynamic measurements of molecular compounds can give macroscopic information of materials. The accurate measurements of the heat capacity, C p , as a function of temperature give information on the enthalpy, H, and the entropy, S, by integrating C p and C p T ¹1 with respect to temperature. Not only the detection of phase transitions by observing thermal anomalies but also possible phase relations including short range correlations can be investigated. 1,2Measurements under tunable external parameters such as pressure, magnetic field, and electric field can give thermodynamics information as a function of these parameters, leading to the detection of external pressure-and field-induced phase transitions and the understanding of their mechanism. Usually, thermodynamic quantities are determined by ensemble averages obeying statistical principles, which are related to microscopic structures, energies, and quantum mechanical properties of component molecules.For molecular assembly systems, such as organic conductors, organic magnets, metal complexes, liquid crystals, etc., physical properties are determined by molecular structures, electronic state of consisting molecules, molecular arrangements, and also molecular dynamics with various time scales. The heat capacity measurements can give information on changes in these microscopic degrees of freedom, and they are effective in detecting phase transitions and cr...

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Dual Association Modes of the 2,5,8‐Tris(pentafluorophenyl)phenalenyl Radical

Uchida

Hirao

Kurata

et al. 2014

Chemistry An Asian Journal

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The 2,5,8-tris(pentafluorophenyl)phenalenyl radical was obtained by a straightforward synthesis in 11 steps from 2,7-dibromonaphthalene. This radical crystallized as a σ dimer from a solution in MeCN and as a π-stack from a melted liquid. The π stack was not confined to dimerization, but extended into a uniform 1D stack with an interplanar distance of 3.503 Å. This unique duality in association mode arose from the thermodynamic stability of the phenalenyl moiety.

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Update 1 of: Calorimetric Investigation of Phase Transitions Occurring in Molecule-Based Magnets

Cited by 96 publications

References 644 publications

Iron(II) Complexes of Tridentate Indazolylpyridine Ligands: Enhanced Spin-Crossover Hysteresis and Ligand-Based Fluorescence

Iron(II) Complexes of Tridentate Indazolylpyridine Ligands: Enhanced Spin-Crossover Hysteresis and Ligand-Based Fluorescence

Thermodynamics of a Liquid-like Spin State in Molecule-based Magnets with Geometric Frustrations

Dual Association Modes of the 2,5,8‐Tris(pentafluorophenyl)phenalenyl Radical

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