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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.

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.

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.

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.

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.

The viologen radical salt (VRS), consisting of phenyl viologen (PV) dications and 2,2,6,6-tetramethyl-1-piperidinyloxy derivative (TEMPOD) anions, was successfully synthesized. The VRS was combined with N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) to form an electrochromic device (ECD). This ECD offers significant transmittance changes (>60% at both 580 and 620 nm), but only requires 0.4 V for switching, the lowest driving voltage ever reported. Such a low driving voltage further strengthens the energy-saving capability of the ECD. The incorporation of TEMPOD in the ECD greatly improved its write–erase ability while insufficient bleaching was clearly observed within only 5 cycles in the case of its counterpart without adding TEMPOD anions. No significant decay in the transmittance change was noticed in the proposed ECD after subjecting to 100 cycles. Even better cycling stability would be expected if counter anions with multiple TEMPO units were utilized.

Electrocrystallisations of the chiral donor molecule S,S-bis(2-hydroxylpropylthio)ethylenedithiotetrathiafulvalene have produced a series of 1 : 1 semiconducting radical-cation salts with anions bromide, chloride, perchlorate and hexafluorophosphate. The flexibility and hydrogen bonding ability of the donor's chiral side chains lead to three quite different packing arrangements of donor cation pairs. Conductivity is maintained despite significant separations of donor cation pairs in some cases.

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.

While an addition product was formed by the reaction of AZADO (2-azaadamantane N-oxyl) with TCNQF4 (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane), the reaction of AZADO with thiourea provided an inclusion compound, in which AZADO molecules are incorporated in cylindrical channels formed by thiourea molecules.

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.

A series of aryl-substituted naphthalenediimide derivatives that contain nitroxide radicals were prepared and their crystal structures were elucidated. Much stronger charge-transfer interactions were present in the derivatives with perfluorobenzene substituents than those with phenyl or 4-fluorophenyl substituents. These interactions result in the formation of single-component charge-transfer complexes by self-assembly of the naphthalenediimide derivatives to provide black crystals. As a consequence, the naphthalenediimide derivatives with perfluorobenzene substituents have better field-effect transistor (FET) properties than the other derivatives.

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.

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.

Several ferrocene derivatives (1–6) carrying nitroxide radical were prepared as dual redox compounds. They have distorted molecular structures and exhibit oxidation potentials based on both ferrocene and nitroxide groups except 4. The multi-step charge–discharge processes are discriminated for mono-substituted derivatives with the first discharge capacity up to 400 Ah kg−1 for imino-derivative 3, while relatively characterless profiles are observed for bis-substituted derivatives 4 and 6 with capacity over 300 Ah kg−1.

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.

A couple of naphthalenediimide 4 and 5 and series of perylenediimide derivatives 6–9 carrying TEMPO radical were prepared and their redox, FET, and magnetic properties were investigated. The radica...

We have prepared new organic anionic acceptors, Br2XQNHCH2SO3− (2: X=Br, 3: X=BryCl1−y (y≈0.5), 4: X=Cl; Q=1,4-benzoquinone), that possess both an electron acceptor part (1,4-benzoquinone) and an anionic part (sulfonate). The reduction potentials of the PPh4 salts of 2, 3 and 4 are −0.45, −0.45 and −0.46 V (vs. SCE in CH3CN), respectively. The results indicate that they are weaker acceptors than chloranil (−0.13 V) and bromanil (−0.12 V). Each anionic acceptor (AA) provided two BEDT-TTF salts, β-(ET)5(AA)2·DCE·zH2O and λ-(ET)2(AA)·CH3OH (AA=2, 3, or 4; z=2: 0.97, 3: 0.83 and 4: 0.40). The structures and transport properties of the salts are reported.

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...

The first chiral BEDT-TTF-tris(oxalato)metallate(III) salt has been crystallised from a solution containing the racemic anion in the chiral solvent (R)-(−)-carvone.

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.

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.

Magnets play a crucial role in a modern life; as we know, a vast number of devices are employed in the electromagnetic industry. In ancient times human beings experienced magnetic phenomena by utilizing natural iron minerals, especially magnetite. It was not until modern times that magnetic phenomena were appreciated from the standpoint of electromagnetics, to which many physicists such as Oersted and Faraday made a great contribution. In particular, Amp e re explained magnetic materials in 1822, based on a small circular electric current. This was the fi rst explanation of a molecular magnet. Furthermore, Amp e re ’ s circuital law introduced the concept of a magnetic moment or magnetic dipoles, similar to electric dipoles. Macroscopic electromagnetic phenomena are depicted in Figure 1.1 , in which a bar magnet and a circuital current in a wire are physically equivalent. Microscopic similarity is shown in Figure 1.2 , in which a magnetic moment or dipole and a microscopic electron rotational motion are comparable but not 1

We have prepared a novel organic anionic weak acceptor, 2-aminomethylsulfo-3,5,6-trichloro-1,4-benzoquinone (1), as a PPh4 salt. Cyclic voltammetry indicates that its reduction potential is 0.53 V lower than that of chloranil. Electrocrystallisation with BEDT-TTF gave two salts, β - β -(BEDT-TTF)2(1)⋅0.5H2O (2) and β ″ - (BEDT-TTF)2(1)⋅CH3OH (3). Their crystal structures and physical properties are reported.

Picosecond optical excitation of electron spin precession has been observed at room temperature by detecting an induced EMF for acetone solutions of tetraethylammonium iron(III) tetrachloride ((C 2 H 5 ) 4 NFeCl 4 ), tetraethylammonium iron(III) tetrabromide ((C 2 H 5 ) 4 NFeBr 4 ), and iron(III) trichloride (FeCl 3 ). A detection bandwidth of 7 GHz allowed the free induction decay (FID) signal with a sub-nanosecond decay time. Magnetic field dependence of the FID frequency for (C 2 H 5 ) 4 NFeCl 4 is well fitted with the Zeeman energy splitting given by the S = 5 2 spin Hamiltonian with a g -value of 2.015±0.007 and a zero fine structure constant. A Fourier transform of the FID waveform shows a Lorentzian shape. The dephasing time T 2 coincides with the longitudinal decay time T 1 and is independent of the magnetic field, indicating that the spin system we studied is under the motional narrowing regime. The optical technique allows Fourier transformed (FT) ESR without microwave excitation at an arbitrary magnetic field.

Over the last decades scientists have faced growing requirements in novel methods of fast and sensitive analysis of antioxidant status of biological systems, spin redox probing and spin trapping, investigation of molecular dynamics, and of convenient models for studies of photophysical and photochemical processes. In approaching this problem, methods based upon the use of dual chromophore-nitroxide (CN) compounds have been suggested and developed. A CN consists of two molecular sub-functionality (a chromophore and a stable nitroxide radical) tethered together by spacers. In the dual compound the nitroxide is a strong intramolecular quencher of the fluorescence from the chromophore fragment. Reduction to hydroxylamine, oxidation of the nitroxide fragment or addition of an active radical yield the fluorescence increase and the parallel decay of the fragment electron spin resonance (ESR) signal. At certain conditions the dual molecules undergo photomagnetic switching and form excited state multi-spin systems. These unique properties of CN were intensively exploited as the basis for several methodologies, which include molecular probing, modeling intramolecular photochemical and photophysical processes, and construction of new magnetic materials.

Series of organic radical compounds with trans -azobenzene chromophore have been prepared to see the photo-induced isomerizations to the corresponding cis -azobenzenes and the possible changes of intermolecular magnetic interactions based on the isomerizations. Although the cis -isomers with p -nitro- or p -dimethylamino-substituent on one side and TEMPO-attached long alkoxy group on the other side could not be isolated as stable solids, the cis -isomers of unsubstituted derivatives at 4-position and with a TEMPO group at 4′-position have successfully been isolated as relatively stable solid materials showing apparent changes of intermolecular magnetic interactions. A couple of Mn(hfac) 2 complexes derived from isomeric TEMPO-substituted esters were found to be reluctant to the photo-isomerization upon irradiation.

Several radical salts derived from a TEMPO-substituted 2,4,6-triphenyl pyridinium have been prepared by replacing the fluoroborate anion with an anionic metal-complex such as Ni(dmit) 2 , Pd(dmit) 2 or Ni(mnt) 2 and their structures and physical properties were investigated. The oxidized salts of the Ni(dmit) 2 as well as Pd(dmit) 2 complexes show semi-conducting properties with relatively high conductivities and low activation energies.

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

Hall resistance and magnetic torque measurements have been carried out in the field-induced spin-density-wave (FISDW) phase of deuterated (TMTSF)2ClO4 for various cooling rates through the anion ordering temperature. We have found that the Hall resistance in the intermediate cooled state shows a phase transition from the non-quantized Hall phase to the quantized Hall phase (n=1) with hysteresis. We have also found that the magnetic torque in the non-quantized Hall phase rapidly decreases with increasing cooling rate. These results suggest that there is a new phase transition from the non-quantized Hall phase to the quantized Hall phase in (TMTSF)2ClO4.

The first radical-cation salts in the extensive family (BEDT-TTF)x[(A)M(C2O4)3]·Guest containing lithium as the counter cation have been synthesized and characterised.

A new BEDT-TTF-based salt with an organic free radical TEMPO has been prepared. The salt consists of alternate layers of conducting and magnetic sheets, between which are short S(BEDT-TTF) …O(TEMPO) contacts. The magnetic susceptibility is well modelled by the combination of a 2D Heisenberg and a Curie–Weiss model with J = − 89 K and θ = + 0.05 K .

The pressure-induced conducting behavior of the charge-transfer salts (BDA-TTP)2X [BDA-TTP=2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene; X=ClO4·H2O, ClO4, BF4·H2O, BF4, and I3] has been investigated. With increasing pressure, the transition temperature to insulator observed in the ClO4·H2O, ClO4, BF4·H2O, and BF4 salts increases. On the other hand, the resistance of the I3 salt as a function of temperature at 10.0 kbar shows a drop attributable to a superconducting transition with an onset at 4.5 K. The superconducting transition temperature (Tc) can reach 8.2 K by applying a pressure of 10.3 kbar, but gradually decreases with further increases in the pressure.

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.

We have measured Hall resistance and magnetic torque in the field-induced spin-density-wave (FISDW) phase of deuterated (TMTSF) 2 ClO 4 for various cooling rates through the anion ordering temperature. The Hall resistance with the magnetic field parallel to c* is not sensitive to cooling rate above 16T. On the other hand, the Hall resistance between 9 and 14 T rapidly and continuously decreases with increasing cooling rate. This result means that the Hall resistance in the semimetallic SDW phase between 9 and 14 T is not quantized in the intermediate cooled states. A new phase transition from the non-quantized phase to the quantized (n = 1) Hall phase exists with hysteresis of the Hall resistance. Moreover, the new phase boundary is shifted towards a lower field when the cooling rate is increased. We have also found that the magnetic torque in the non-quantized phase rapidly decreases with increasing cooling rate. A possible ground state of non-quantized and Hall phase of the FISDW phase of (TMTSF) 2 ClO 4 is discussed from the viewpoint of the peculiar SDW nesting vector.

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.

Series of monoradicals and biradicals having an aromatic core on one hand and long alkyl groups on the other hand have been prepared. It was found from their magnetic data that the biradical compounds having aromatic cores (azoxy, or azo) and long alkyl groups with TEMPO radicals at their ends showed fairly large antiferromagnetic interactions ( J = −34, −39 K) being well expressed by ST model, while only weak antiferromagnetic interactions were observed in the corresponding PROXYL derivatives together with the corresponding monoradicals. The change of intermolecular magnetic interactions based on the structural change from trans - to cis -isomer by irradiation was found to be possible in a couple of azobenzene derivatives with an aminoxyl radical.

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.