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.

Doping effect of buckminsterfullerene in conducting polymer: Change of absorption spectrum and quenching of luminescene

We introduce the development of conductive organic molecular assemblies including organic metals, superconductors, single component conductors, conductive films, and conductive liquids, particularl...

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

Toward systematic understanding of diversity of electronic properties in low-dimensional molecular solids.

Well conducted: a two-dimensional porphyrin covalent organic framework is described. Owing to the eclipsed stacking alignment, the framework is conductive and allows high-rate carrier transport through the porphyrin columns. The central metal in the porphyrin rings changes the conducting nature of the material from hole to electron, and to ambipolar conduction. It also drives the high on-off ratio photoconductivity of the framework.

High‐Rate Charge‐Carrier Transport in Porphyrin Covalent Organic Frameworks: Switching from Hole to Electron to Ambipolar Conduction

Optical and electrical properties of an organic superconductor di[bis(ethylenedithio)tetrathiafulvalenium dithiocuanocuprateI, (BEDT- TTF 2 [Cu(SCN ) 2 ]

Evolution of superconductivity of KxC60 upon K-doping : microwave low-field signal and ESR study

We have succeeded in synthesis of C 60 single crsytals with orthorhombic lattice structure contrary to the known cubic form. The structure of the orthorhombic form was confirmed by a four-circle X-ray diffractometer. The intense microwave absorption signal in low magnetic field was detected on the K-doped C 60 single crystals with the onset of superconductivity at Tc = 17.7 K.

Structure and superconductivity of single crystalline C60

Reflectance spectra of β -, θ -, and κ-(BEDT-TTF)2I3, and β″- and β′-(BEDT-TTF)2ICl2: Relation between the inter-band transition and the dimeric structure

Temperature dependence of the polarized reflectance spectra have been measured on the single crystals of (DMe-DCNQI)2Ag, (DMe-DCNQI)2Na, (MeBr-DCNQI)2Cu, and (DMe-DCNQI)2−Cu (DCNQI stands for dicyanoquinonediimine). The optical spectra evidence one-dimensional band structures of Ag- and Na-salts and anisotropic three-dimensional ones of Cu-salts. The dimensionality crossover is found in (MeBr-DCNQI)2Cu around the metal-insulator phase transition.

A. Ugawa

Papers

Optical and electrical properties of an organic superconductor di[bis(ethylenedithio)tetrathiafulvalenium dithiocuanocuprateI, (BEDT- TTF 2 [Cu(SCN ) 2 ]

Evolution of superconductivity of KxC60 upon K-doping : microwave low-field signal and ESR study

Structure and superconductivity of single crystalline C60

Reflectance spectra of β -, θ -, and κ-(BEDT-TTF)2I3, and β″- and β′-(BEDT-TTF)2ICl2: Relation between the inter-band transition and the dimeric structure

Polarized reflectance spectra of DCNQI salts