Redox Regulation of Cellular Signalling

The Fermi gas model of one-dimensional conductors is reviewed. The exact solutions known for particular values of the coupling constants in a single chain problem (Tomonaga model, Luther-Emery model) are discussed. Renormalization group arguments are used to extend these solutions to arbitrary values of the couplings. The instabilities and possible ground states are studied by investigating the behaviour of the response functions. The relationship between this model and others is discussed and is used to obtain further information about the behaviour of the system. The model is generalized to a set of coupled chains to describe quasi-one-dimensional systems. The crossover from one-dimensional to three-dimensional behaviour and the type of ordering are discussed.

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The Fermi gas model of one-dimensional conductors

We review the progress in the theory of one-dimensional (ID) Fermi liquids which has occurred over the past decade. The usual Fermi liquid theory, based on a quasi-particle picture, breaks down in one dimension because of the Peierls divergence in the particle-hole bubble, producing anomalous dimensions of operators, and because of charge-spin separation. Both are related to the importance of scattering processes transferring finite momentum. A description of the low-energy properties of gapless 1D quantum systems can be based on the exactly solvable Luttinger model which incorporates these features, and whose correlation functions can be calculated. Special properties of the eigenvalue spectrum, parameterized by one renormalized velocity and one effective coupling constant per degree of freedom, fully describe the physics of this model. Other gapless 1D models share these properties in a low-energy subspace. The concept of a Luttinger liquid implies that their low-energy properties are described by an effective Luttinger model, and constitutes the universality class of these quantum systems. Once the mapping on the Luttinger model is achieved, one has an asymptotically exact solution of the 1D many-body problem. Lattice models identified as Luttinger liquids include the 1D Hubbard model off half-filling, and variants such as the t-J- or the extended Hubbard model. In addition, 1D electron-phonon systems or metals with impurities can be Luttinger liquids, as well as the edge states in the quantum Hall effect.

https://iopscience.iop.org/article/10.1088/0034-4885/58/9/002/pdf

One-dimensional Fermi liquids

This review attempts to present the most salient developments of research on organic conductors and superconductors during the past 10 years. A theoretical introduction treats instabilities of quasi-one-dimensional electron systems and associated precursor effects which are relevant to the experimental results on organic conductors. We then describe the characterization of quasi-one-dimensional organic conductors by their transport, optical and magnetic properties. Finally, two sections are devoted to the experimental investigation of the low temperature instabilities: lattice instability in TTF-TCNQ and related compounds, superconducting or antiferromagnetic instabilities in the (TMTSF) 2 X series. The importance of one-dimensional fluctuations is emphasized in both lattice and superconducting instabilities.

Organic conductors and superconductors

Tetrathiafulvalene (TTF) and its derivatives were originally prepared as strong electron-donor molecules for the development of electrically conducting materials. This Review emphasizes how TTF and its derivatives offer new and in some cases little-exploited possibilities at the molecular to the supramolecular levels, as well as in macromolecular aspects. TTF is a well-established molecule whose interest goes beyond the field of materials chemistry to be considered an important building block in supramolecular chemistry, crystal engineering, and in systems able to operate as machines. At the molecular level, TTF is a readily available molecule which displays a strong electron-donor ability. However, its use as a catalyst for radical-polar crossover reactions, thus mimicking samarium iodide chemistry, has only recently been addressed. Important goals have been achieved in the use of TTF at the macromolecular level where TTF-containing oligomers, polymers, and dendrimers have allowed the preparation of new materials that integrate the unique properties of TTF with the processability and stability that macromolecules display. The TTF molecule has also been successfully used in the construction of redox-active supramolecular systems. Thus, chemical sensors and redox-switchable ligands have been prepared from TTF while molecular shuttles and molecular switches have been prepared from TTF-containing rotaxanes and catenanes. A large synthetic effort has been devoted to the preparation of the so-called organic ferromagnets, many of which are derived from TTF. The main task in these systems is the introduction of ferromagnetic coupling between the conduction electrons and localized electrons. TTF has also played a prominent role in molecular electronics where TTF-containing D-sigma-A molecules have allowed the preparation of the first confirmed unimolecular rectifier. Recently, it has been confirmed that TTF can display efficient nonlinear optic (NLO) responses in the second and third harmonic generation as well as a good thermal stability. These findings can be combined with the redox ability of TTF as an external stimuli to provide a promising strategy for the molecular engineering of switchable NLO materials. Fullerenes endowed with TTF exhibit outstanding photophysical properties leading to charge-separated (CS) states that show remarkable lifetimes.

New Concepts in Tetrathiafulvalene Chemistry.

We report the superconductivity with the onset temperature as high as 8 K in the organic conductor of β-(BEDT-TTF) 2 I 3 , bis-ethylenedithio otetrathiofulvalene-triiodide. The increased superconducting transition temperature was achieved by an application of a soft pressure, i.e. 1.3 kb. High value of the upper critical field, H c2 was observed. ( H c2 >13 kOe at 1.5 K along the c * -axis.)

Superconductivity with the Onset at 8 K in the Organic Conductor β-(BEDT-TTF)2I3 under Pressure

By the X-ray scattering measurements of TTF-TCNQ, two anomalies at q b =0.29 b * and 0.41 b * are studied, where q b is the component of the wave vectors of phonons and superstructures along the b * -axis. The anomaly at 0.29 b * appears in the TA phonon mode below 150 K and becomes the superstructure below 54 K. The anomaly at 0.41 b * appears in the LA phonon mode below room temperature and it also forms the superstructure below 54 K. It is concluded that the wave vector of the modulation of the superstructure at 0.41 b * (which is equivalent to 0.59 b * in the reduced zone scheme) is twice the wave vector of that at 0.29 b * (including the temperature dependent a * -component). Further, it was found that the wave number of the phonon anomaly at 0.41 b * varies from 0.41 b * to 0.45 b * with increasing temperature from 150 K to room temperature.

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X-Ray Scattering Study of Phonon Anomalies and Superstructures in TTF–TCNQ

Evidences of the Kohn anomaly and the Peierls transition in TTF-TCNQ were found by X-ray scattering experiments. The Kohn anomalies observed at T =293 K and 63 K give the Fermi wave number, k F , of the one-dimensional electron system as 2 k F = b * /(3.7±0.2), where b * is the reciprocal lattice vector. At 54 K, the one-dimensional ordering of the lattice deformation due to the Peierls transition was found along the b -axis with the period of b '=(3.7±0.2) b . At 27 K, the three-dimensional ordering was observed giving the new unit cell as a '=4 a , b '=3.7 b and c '= c .

Observation of the Kohn Anomaly and the Peierls Transition in TTF-TCNQ by X-Ray Scattering

Nitroxide radicals play a central role in the recent development of organomagnetic materials or molecular-based magnetic materials. This feature article considers the recent progress in the development of molecular-based magnetic materials dealing mainly with nitroxide radical crystals and charge transfer (CT) complexes consisting of nitroxide radicals. We present a view of the progress of this rapidly growing field of materials science over the past few years, showing the results of several research groups (including ours) based on nitroxide radicals in order to introduce the readers to the present situation and to further perspectives to possible degree.

Recent progress in the development of organomagnetic materials based on neutral nitroxide radicals and charge transfer complexes derived from nitroxide radicals

Hiroyuki Anzai

Papers

Superconductivity with the Onset at 8 K in the Organic Conductor β-(BEDT-TTF)2I3 under Pressure

X-Ray Scattering Study of Phonon Anomalies and Superstructures in TTF–TCNQ

Observation of the Kohn Anomaly and the Peierls Transition in TTF-TCNQ by X-Ray Scattering

Recent progress in the development of organomagnetic materials based on neutral nitroxide radicals and charge transfer complexes derived from nitroxide radicals

A possible immunosuppressant, cycloprodigiosin hydrochloride, obtained from Pseudoalteromonas denitrificans