Conductivity cationic

The only new chemistry concerns electrochemical oxidation of the tetrathiafulvene derivative 41 to the radical cation perchlorate 42 (Equation 1) <2005MCL575>. The salt 42 was formed electrochemically as a dense thin film on the electrode surface and shown to be a conducting cation-radical salt that behaves like an organic metal. The electrical conductivity shows an interesting variation with temperature which may be related to a phase transition at 102K <2005MCL575>. 

Electrical conductance, cation transference number and activity coefficient of the halide systems are discussed on page 37. 

Probably the best known early crown ether example is the chundle reported by Jullien and Lehn (Jullien and Lehn, 1988). Their strategy used a central crown ether unit with sidearms radiating from it. The stereochemistry of the sidearms was fixed by incorporation of tartaric acid units within the macrocycle. The name was given because the compound was a channel formed from a bundle of fibers. In this first report, no information about insertion or transport appeared, and the assertion that the compound was a channel apparently rested on the intent of the design. Later work from this group showed that related compounds, called bouquet molecules, did conduct cations, albeit rather slowly (Canceill etal., 1992). 

MacFarlane et al. [129] and Watanabe et al. [24a, 114] discussed the difference in diffusivity of component ions. Reported diffusion coefficients of ILs are shown in Table 3.19 together with viscosity and ionic conductivity. From that table, it is easy to see that lower viscosity ILs show larger diffusion coefficients and higher ionic conductivity. Cations generally have larger diffusion coefficient values than do anions in ILs. This means that the cation diffuses more easily than the anion. However, the transference numbers of onium cation (t+) in ILs calculated from the results of PFG-NMR is in the range 0.5 to 0.6 and their contribution to the ionic conductivity is mostly the same, irrespective of the ion species. In the case of [bpy][BF4], the BF4- shows a larger diffusion coefficient than that of bpy+, and therefore t+ is below 0.5 [24a], Thus, as well as thermal and electrochemical properties, the diffusion behavior of component ions is dependent on their structure. 

The ability of compounds 21, 22, 23, 25, and 28-32 to conduct cations was examined in planar bilayers composed of phosphatidylethanolamine (PE) painted across a 200 pm diameter aperture in a septum between two aqueous compartments filled with 600 mM KC1 (10 mM HEPES pH 7.2) (Figure 13). Bilayer quiescence was confirmed at 148 mV and bilayer stability was observed to be unaffected by the addition of up to 5 pL of DMSO. Stock solutions of the channel compounds (10 pM) were prepared immediately prior to use, and 0.1-5 pL (i.e. 1-50 pmol of substance) in DMSO was added to the stirred solution in the cis chamber. Typically, channel insertion into the bilayer occurred between 30 s and 30 min. 

Polymer electrolytes conduct cations by segmental motions of the polymer backbone that carry the cations from one complexation site to the next.60-62 Since this requires significant fluidity, the polymers are conductive only in the amorphous state, i.e. above the crystalline to gel transition temperature. For the bulk polymer of PHB, this temperature is in the range of 0° to 10 °C. Accordingly, single molecules of PHB dissolved in fluid lipid bilayers should be capable of considerable segmental motions at physiological temperatures. 

Fig. 4-12. HPICE chromatogram of a human serum. - Separator column IonPac ICE-AS2 (precursor of IonPac ICE-AS1) eluent 0.01 mol/L HC1 flow rate 0.8 mL/ min detection suppressed conductivity (cation exchanger in Ag form) (A) strong inorganic acids, (B) phosphoric acid group, (C) pyruvic add group, (D) lactic acid group, (E) hydroxybutyric acid group.

The study of electrical conductivity of molten salts is one of the indirect methods used for the determination of molten salts structure and of component interaction in molten mixtures. The change in composition of a molten mixture is often accompanied by structural changes, which affect the dependence character of the electrical conductivity on composition. Consequently, an analysis of this dependence should provide some information regarding the present ionic species and their arrangement in the melt. Supplementary information, i.e. concerning the formation and decomposition of complex ions, the character of the cation-anion bond, and the character of conductivity, cationic, anionic, electronic, etc., can be obtained from analysis of the dependence of the activation energy on composition. 

In the polymer electrolyte fuel cell (PEFC), proton-conducting cation-exchange membranes are used as electrolyte, which consist of an organic... 

Early progress in polythiophene chemistry was achieved by the synthesis of mono- and dialkoxy-substituted thiophene derivatives developed by Leclerc [6] and industrial scientists at Hoechst AG [7-9]. However, most polymers of mono- and dialkoxythiophenes exhibited low conductivity in the oxidized, doped state. A breakthrough in this area was the synthesis of polymers of the bicyclic 3,4-ethylenedioxythiophene (EDT or EDOT) and its derivatives—electrochemically polymerized by Heinze et al. and chemically polymerized by Jonas et al. of the Bayer Corporate Research Laboratories [10,11]. In contrast to the nonbicyclic polymers of mono- and dialkoxythiophenes, PEDT has a very stable and highly conductive cationic doped state. The low HOMO-LUMO bandgap of conductive PEDT allowed the formation of a tremendously stable, highly conductive ICP [12]. Technical use and commercialization quickly followed today ICPs based on PEDT are commercially available in multiton quantities. 

Since in situ PEDT polymers are quite insoluble in most commonly used solvents, in situ PEDT cannot be easily made into a processable, coatable solution. However, an industrially usefiil form of oxidized PEDT can be made by aqueous oxidative polymerization of the EDT monomer in the presence of a template polymer, usually polystyrene sulfonic acid (PSS or PSSA). PSS is a commercially available water-soluble polymer and can thus serve as a good dispersant for aqueous PEDT. Polymerization with the oxidant sodium peroxodisulfate yields a PEDT PSS-complex in its conductive, cationic form (Figure 10.5). 

Semi-)Conductivity Cation formation Metallic character Polymer formation... 

Sensors are typically based upon SO2 concentration cells with a reference SO2 gas circulation (Imanaka et al. 1986, Adachi and Imanaka 1995). The principle of sensing is based upon equilibrium being achieved between the conducting cation, Na+ and the gas phase containing SO3 and O2. In fact the emf is related to the concentration in the gas phase of the two electrodes by the following equation ... 

K. Takahashi, T. Ise, T. Mori, H. Mori and S. Tanaka, Synthesis of BEDT-BDTBS and crystal structures of its conducting cation radical salts, Chem. Lett., 1001-1002 (1996). 

Electrical resistance or electrical conductivity Cation- and anion content, salt content, silicate content (Si02)... 

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