Tetrathiafulvalene compounds

Single-Stack Donor. Ion-radical salts can also be formed from electron donors such as tetrathiafulvalene (TTE) or TMPD (N,N,N N-tetramethyl- phenylene diamine) with inorganic acceptors such as halogens. The resulting stmcture of compounds such as TTE(A)... 

Whereas the fulvalenes 1-6 are relatively unstable hydrocarbons and therefore largely of theoretical interest, their heteroatom analogs demand considerable attention in synthetic chemistry and material sciences. Tlie general principle of heterocyclic chemistry to relate heterocyclic compounds to carbocyclic ones was the driving force for the synthesis and their application to heteroful-valenes. Numerous heterocyclic derivatives iso-rr-electronic with, for example, heptafulvalene 3 were accessible in which pairs of carbon atoms linked by double bonds were replaced by heteroatoms capable of contributing two tt-electrons. By this principle, the well-known tetrathiafulvalene and its derivatives have been synthesized successfully (Scheme 2). 

Certain abbreviations are used in the article for compounds that are mentioned repeatedly. Tlius, TTF is tetrathiafulvalene, TCNQ is tetracyanoquin-odimethane, TTDAF is tetrathiadiazafulvalene, DTDAF is dithiadiazafulva-lene, and TAF is tetraazafulvalene. 

Extended tetrathiafulvalenes with acetylenic cores are interesting compounds because of their redox and chromophoric properties. Such molecules are both interesting from materials and supramolecular chemistry perspectives. A tetraethynylethene-extended tetrathiafulvalene, for instance, was prepared using a microwave-promoted Sonogashira reaction [72]. Coup-... 

A C60 derivative with an attached fluorinated chain gave a limiting area of 0.78 nm molecule [266]. It was reported that this film was so mechanically rigid that it pushed the Wilhehny plate out of the water at 11 14 mN m The monolayer spreading of this compound arises from the even greater hydrophobicity of the fluorocarbon chains and their orientation away from the water surface. The LB films with a fluorinated tetrathiafulvalene derivative did not show evidence of charge transfer in their UV spectra. 

The silver(I) complexes with the tetrakis(methylthio)tetrathiafulvalene ligand have been reported, the nitrate salt presents a 3D structure with an unprecedented 4.16-net porous inorganic layer of silver nitrate,1160 the triflate salt presents a two interwoven polymeric chain structure.1161 The latter behaves as a semiconductor when doped with iodine. With a similar ligand, 2,5-bis-(5,5,-bis(methylthio)-l,3,-dithiol-2 -ylidene)-l,3,4,6-tetrathiapentalene, a 3D supramolecular network is constructed via coordination bonds and S"-S contacts. The iodine-doped compound is highly conductive.1162 (Methylthio)methyl-substituted calix[4]arenes have been used as silver-selective chemically modified field effect transistors and as potential extractants for Ag1.1163,1164... 

Electron mediators successfully used with oxidases include 2,6-dichlorophenolindophol, hexacyanoferrate-(III), tetrathiafulvalene, tetracyano-p-quinodimethane, various quinones and ferrocene derivatices. From Marcus theory it is evident that for long-range electron transfer the reorganization energies of the redox compound have to be low. Additionally, the redox potential of the mediator should be about 0 to 100 mV vs. standard calomel electrode (SCE) for a flavoprotein (formal potential of glucose oxidase is about -450 mV vs SCE) in order to attain rapid vectrial electron transfer from the active site of the enzyme to the oxidized form of the redox species. 

Tetrathiafulvalene (TTF), 23 707 electrochromic material, 6 581, 581t polymers of, 23 708-709 Tetrathiomolybdate ion, 17 22-23 Tetravalent lead, 14 783 Tetravalent manganese compounds,... 

The following compounds are the most popular donors for organic metals (see Scheme 8.9) TTF, tetraselenafulvalene (TSeF), tetrathiatetracene (TTT), tetraselenatetracene (TSeT), tetra-methyl tetraselenafulvalene (TMeTSeF), bis(thiadimethylene) tetrathiafulvalene (BTDM-TTF), bis(ethylenedithia) tetrathiafulvalene (BEDT TTF or ET), tetrakis(methyltelluro) tetrathiafulvalene (TTeCj-TTF), tetramethylbis(ethylenedithia) tetrathiafulvalene (TMET), 2,2 -(2,6-naphthalenediy-lydene) bis(l,3-dithiole) (NBDT). All the abbreviations are those used in the current literature. 

Neilands O (2001) Dioxo-and aminooxopyrimido-fused tetrathiafulvalenes-base compounds for novel organic semiconductors and for design of sensors for recognition of nucleic acid components. Mol Cryst Liq Cryst 355 331-349... 

Koshihara S, Tokura Y, Mitani T, Saito G, Koda T (1990) Photoinduced valence instability in the organic molecular compound tetrathiafulvalene-p-chloranil (TTF-CA). Phys Rev B42 6853-6856... 

Bousseau L, Valade L, Legros JP, Cassoux P, Garbauskas M, Interrante LV (1986) Highly conducting charge-transfer compounds of tetrathiafulvalene and transition metal- dmit complexes. J Am Chem Soc 108 1908-1916... 

There has again been a large amount of work on tetrathiafulvalenes (TTFs) and derivatives and a short review of such compounds has appeared <99M1617>. New simple TTF derivatives prepared include the terakis-bromomethyl compound <99TL2927> and doubly C-labelled... 

Tetrathiafulvalene derivatives undergo reaction with nucleophiles, such as 195, to produce the linearly-fused TTF compounds such as 51 in reasonable yields (Equation 130). A small amount of the angularly substituted regioisomer is... 

The prospective applications ofmolecular assemblies seem so wide that their limits are difficult to set. The sizes of electronic devices in the computer industry are close to their lower limits. One simply cannot fit many more electronic elements into a cell since the walls between the elements in the cell would become too thin to insulate them effectively. Thus further miniaturization of today s devices will soon be virtually impossible. Therefore, another approach from bottom up was proposed. It consists in the creation of electronic devices of the size of a single molecule or of a well-defined molecular aggregate. This is an enormous technological task and only the first steps in this direction have been taken. In the future, organic compounds and supramolecular complexes will serve as conductors, as well as semi- and superconductors, since they can be easily obtained with sufficient, controllable purity and their properties can be fine tuned by minor adjustments of their structures. For instance, the charge-transfer complex of tetrathiafulvalene 21 with tetramethylquinodimethane 22 exhibits room- temperature conductivity [30] close to that of metals. Therefore it could be called an organic metal. Several systems which could serve as molecular devices have been proposed. One example of such a system which can also act as a sensor consists of a basic solution of phenolophthalein dye 10b with P-cyciodextrin 11. The purple solution of the dye not only loses its colour upon the complexation but the colour comes back when the solution is heated [31]. 

As a final example, let us mention that Little 143,144) has discussed the possibility of obtaining organic superconductors that operate at high temperature. The first superconductive model compound to be proposed was a polymethine chain connected with highly polarizable sensitizing cyanine dyes (see e.g. Table 3). The first report on superconducting fluctuations in tetrathiafulvalene-tetra-cyanochinodimethane crystals appeared recently 145>. 2... 

Tetrathiafulvalene and its derivatives are electroactive and can be easily and reversibly oxidized to TTF + and TTF2 +. The TTF skeleton now occupies a critical position as far as switchable properties are concerned, and behaves as a key unit for a number of supramolecular concepts. For instance, the recent years have seen an increasing contribution of TTF to the preparation of interlocked compounds such as rotaxanes and catenanes. These systems are of particular importance as candidates for molecular machines. 

The precursor dithiocarbonates were also used to prepare mesomorphic derivatives of TTF (tetrathiafulvalene), a strong electron donor compound used in the formation of highly conductive charge transfer complexes. Attempts to prepare CT complexes between the mesomorphic dithiolenes as acceptors and these mesomorphic TTF donors showed that the electron acceptor strength of this type of dithiolene does not suffice to form strong donor-acceptor complexes mixtures of the two components form mixed crystals without any visible degree of charge transfer.208... 

The combination of a phthalocyanine ring with crown ether moieties and redox-active tetrathiafulvalenes gave compound 117 (Scheme 64) and was described by Zou as a good candidate for a redox-active Na+ sensor [133]. 

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