TTF-TCNQ composites

Figure 19 Dependence of electrical conductivity crM and activation energy Ea of TTF/TCNQ composites on molar fraction x of donor TTF. (From Ref. 87.)...

Figure 21 Dependence of crM and of Ea at low x values (TTF/TCNQ composites). Note the logarithmic scales. (From Ref. 86.)...

Based on poly(vinyl chloride) tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) composite electrode... 

A PVC/TTF-TCNQ composite electrode is employed as detector for the simultaneous detection of AA and uric acid... 

Cano, M., B. Palenzuela, and R. Rodriguez-Amaro. 2006. A PVC/TTF-TCNQ composite electrode for use as a detector in flow injection analysis. Electroanalysis 18 1727-1729. 

What makes the TTF-TCNQ family distinct from the other salts of TCNQ with cations, such as alkali metals and tetramethylammonium, is that the charge transfer,/ in the TTF-TCNQ family is incomplete (f < 1). TTF-TCNQ members are also different from the TTF-halides in the TTF-halides, where the charge on each halide atom is unity, partial charge transfer (mixed valency) is realized by the formation of nonstoichiometric materials, while in the TTF-TCNQ family, the composition is stoichiometric (1 1), but mixed valence arises because of partial electron-transfer. 

Llopis et al. [37] Cola beverage Glucose oxidase (GOD)/ entrapped together with the mediator in the bulk of the biocomposite material Graphite and nonconducting epoxy resin composite electrode/ +0.3 V vs. Ag/AgCl Tetrathiafulvalene-tetracyanoquino-dimethane (TTF - TCNQ)... 

Incommensurate structures have been known for a long time in minerals, whereas TTF-TCNQ is one of the very first organic material in which a incommensurate phase has been observed. There are two main types of incommensurate crystal structures. The first class is that of intergrowth or composite structures, where two (or more) mutually incommensurate substructures coexist, each with a different three-dimensional translational periodicity. As a result, the composite crystal consists of several modulated substructures, which penetrate each other and we cannot say which is the host substructure. The second class is that of a basic triperiodic structure which exhibits a periodic distortion either of the atomic positions (displa-cive modulation) and/or of the occupation probability of atoms (density modulation). When the distortion is commensurate with the translation period of the underlying lattice, the result is a superstructure otherwise, it is an incommensurately modulated structure (IMS) that has no three-dimensional lattice periodicity. 

Several groups have reported work with polymer films that resemble composite materials in that conductive particles are dispersed within the film. These include TTF-TCNQ (106), carbon... 

Particles may also be incorporated into composite-type electrodes. Zeolites have been incorporated into carbon paste (91,9 ) and TTF-TCNQ has been incorporated into polymer paste (115). Solid crosslinked-polystyrene-composite electrodes modified with alumina, layered double hydroxides, and zeolites were shown to have useful analytical and electrocatalytic properties (78). 

For example, at a ratio of molecular iodine to tetrathiatetracene (TTT) of 1 2, mixtures of iodides (TTT)i(I)i and (TTT)2(I)3 can be obtained on fast cooling. Slow cooling of the same component mixture in the same proportion leads to the single product (TTT)2(I)3. The latter is just the product that possesses metallic properties. Sometimes, even at nonstoichiometric ratio, salts of the 1 1 composition are formed. Interaction between TTF and TCNQ can be exemplified. To obtain the 2 1 composition, an indirect synthesis is appropriate. The synthesis is based on an exchange reaction of the following type ... 

Recent work (Lupinski et al., 1967 Hadek et al., 1971 Barlow et al., 1976) has shown that the maximum conductivity depends critically upon the precise composition of the complex salts and is essentially controlled by the neutral impurity molecules. Just as radical anion salts are based on strong electron acceptors such as TCNQ, radical cation salts based on strong electron donors such as TTF are also known. A listing of the more important radical ion salts is included in Table 3. As a rule these salts give rise to an intense esr signal with their spin concentrations reaching 1 to 1.5 spins per DA pair. 

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