7.7.8.8- Tetracyanoquinodi-methane

Typical Applications EPR spectra were obtained for both the interfacial reduction of 7,7,8,8,-tetracyanoquinodi-methane (TCNQ) and oxidation of tetrathi-afulvalene (TTF), when dissolved in DCE by the aqueous phase ferri/ferrocyanide redox couple, following the application of a potential difference directly to the liquid I liquid interface. Previous work [111, 112] suggested that a charge-transfer process occurs at the liquid liquid interface, due to the heterogeneous reduction of TCNQ by the aqueous couple,... 

Allyl (27, 60, 119-125) and benzyl (26, 27, 60, 121, 125-133) radicals have been studied intensively. Other theoretical studies have concerned pentadienyl (60,124), triphenylmethyl-type radicals (27), odd polyenes and odd a,w-diphenylpolyenes (60), radicals of the benzyl and phenalenyl types (60), cyclohexadienyl and a-hydronaphthyl (134), radical ions of nonalternant hydrocarbons (11, 135), radical anions derived from nitroso- and nitrobenzene, benzonitrile, and four polycyanobenzenes (10), anilino and phenoxyl radicals (130), tetramethyl-p-phenylenediamine radical cation (56), tetracyanoquinodi-methane radical anion (62), perfluoro-2,l,3-benzoselenadiazole radical anion (136), 0-protonated neutral aromatic ketyl radicals (137), benzene cation (138), benzene anion (139-141), paracyclophane radical anion (141), sulfur-containing conjugated radicals (142), nitrogen-containing violenes (143), and p-semi-quinones (17, 144, 145). Some representative results are presented in Figure 12. 

Another experimental example of the effect of chemical reactions on voltammetry in resistive media is given by the reduction of tetracyanoquinodi-methane (TCNQ) in acetonitrile. At high ionic strength, voltammograms of TCNQ have two one-electron waves of equal amplitude [75]. The waves correspond to the following electrochemical processes ... 

The ionization constants,331 NMR spectra,174 and mass spectra1227 of representative amino-1,6-naphthyridines have been compared with those of related amino derivatives. Complexes of l,6-naphthyridin-2-amines with tetracyanoquinodi-methane have been studied.416 4-(3-Dimethylamino-l-methylpropylamino)-l,6-naphthyridine showed significant antimalarial activity.236 X-ray analyses of a number of 5-amino-1,6-naphthyridines have been reported in connection with their antibacterial activities for example, ethyl 5-amino-7-benzylseleno-8-cyano-4-(fur-2-yl)-l,2-dimethyl-l,4-dihydro-l,6-naphthyridine-3-carboxylate (10) proved to be a mixture of two symmetric conformers in each crystal 772 the other related compounds appear to be composed of single conformers.558,560 562 759 781 1289... 

Acetylcholineesterase and choline oxidase Enzyme immobilized over tetra-thiafulvalene tetracyanoquinodi-methane crystals packed into a cavity at the tip of a carbon-fiber electrode. The immobilization matrix consisted of dialdehyde starch/glutaraldehyde, and the sensor was covered with an outer Nafion membrane. The ampero-metric performance of the sensor was studied with the use of FIA system. An applied potential of +100 mV versus SCE (Pt-wire auxiliary electrode) and a carrier flow rate of 1 mL/min. The Ch and ACh biosensors exhibited linear response upto 100 pM and 50 pM, respectively. Response times were 8.2 s. [97]... 

Crystalline mixtures of the dimers (150-152) with tetracyanoquinodi-methane (153) undergo photoinduced intermolecular electron transfer when irradiated at >350 nm. Cleavage of the C-C bond and the formation of the monomers then occurs. The photochromic properties of the chromene (154) have been studied.The ring opening kinetics using 357 nm were measured and ring closure was effected by irradiation at 422 nm. The quantum yields of the forward and back processes were also measured. Kaneko and coworkers have studied the photochemical cyclization of the enediyne (155) which forms the aromatic compound (156). The best yields are obtained using hexane as the solvent. 

The temperature dependence of the dynamic nuclear polarization enhancement (A ) of the protons in tetrathiafulvalinium tetracyanoquinodi-methane (TTF-TCNQ) and potassium TCNQ (K.TCNQ) is reported. Theoretical expression of A is given experimental results are discussed and allow us to... 

More recently, crystalline cation-radical anion-radical salts of the donor tetrathiofulvalene with the acceptors tetracyanoquinodi-methane (Phillips et al., 1973 Ferraris et al., 1973 Butler et al., 1974) and tetracyanomuconitrile (WudI and Southwick, 1974) have... 

Section 15.7 contains tables of magnetic data obtained from anion radicals of compounds fliat don t comfortably fall into any of the previous sections. The subsection on fullerene anion radicals requires a special note as there are several papers of around the same period which vary shghtly in the preparation, solvent or physical parameters of the measurements. As the only data in many cases is the g factor it was decided to include the majority of these entries even though they relate to the same species. The data have been divided into the following subsections sulphides and sulphones, imines and imides, fullerenes, tetracyanoquinodi-methanes, phenylcarbonitriles, phosphaaUcenes and alkylcyclosilanes. Some of these subsections have been further subdivided. 

Fig. 7 Cyclic voltammetric break-in of a poly(tetracyanoquinodi methane) electrode. Electrolyte 2.5 M LiCl. Sweep rate 6 mV. (a) Consecutive cyclic voltammograms, (b) simultaneously obtained EQCM frequency curves [148].

The stabilization of the radical cation in SDS micelles is consistent with the formation of the surface complex already mentioned in Sect. 2.1.1. There are a number of examples of the stabilization of radical ions in micelles of the opposite sign. The electrochemical reduction of nitrobenzene in homogeneous solutions is two-electronic, but in micellar CTAB solutions it is resolved into two separate reactions [135]. So the presence of cationic micelles inhibits the disproportionation of nitrobenzene radical anions. It may be caused by the reduced mobility of the radical ions in the surface layer of the micelles due to complex formation with the end groups of the micelles. It can account for the inhibition of the disproportionation because the latter needs a coUision of two radical ions. The salt formation of the radical cation of N-methylphenothiazine with the end groups of SDS micelles was proposed in the study of electrochemical oxidation of N-methylphenothiazine in micellar solution [136]. Tetracyanoquinodi-methane is solubilized in dodecylpyridinium-inverted micelles in the form of a radical anion with the oxidation of the iodide ion [137]. 

One of the most interesting developments in 1,3-dithiole chemistry is the discovery that the complex formed between the 2,2 -bi-1,3-dithiole (74 R = H) and tetracyanoquinodi methane (75) has remarkable electrical properties, behaving like a metal over a large temperature range. This intensely... 

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