Iodine, complex conductivities

The poly-(2-vinyl pyridine) is present in the cathode to solubilize the iodine via a complexation facilitating its diffusion. On fabrication, the cathode sheet, an iodine complex in a mixture with excess elemental iodine, is pressed against the Li metal anode. On contact a thin passivating, but Li-ion conductive, film of Lil is formed. It fails to grow further until the circuit is closed. Because the conductiv-... 

Cross-linked polymers produced in this way cannot be worked easily. In this respect, charge transfer complexes from polymeric donors and acceptors are more advantageous. The poly(2-vinyl pyridine) and iodine complex, for example, has a specific conductivity of 10 H" cm . It is used as a cathode in Li/h batteries for implantable heart pacemakers. This solid state battery has a higher energy density than the best lead accumulators and a lifetime of about ten years. 

All the conductivity titrations showed a well-developed maximum at the 2/3 stoichiometry for phenothiazine derivative iodine complexes. The curves obtained with the meprazine and perazine derivatives are shown in Figures 8 and 9, respectively. 

Moller, M., and Lenz, R. W., Poly(2-vinylpyridine) block copolymers. Phase separation and electronic conductivity of iodine complexes, Makromol Chem., 190, 1153-1168... 

An XPS investigation [109] of iodine complexes of the copolymer revealed that electrical conductivity. Is content and amount of positively charged nitrogen decrease with increasing concentration of A/-methylpyr-role units in the doped copolymer. 

The simultaneous polymerization and oxidation of azulene with bromine or iodine in acetonitrile have recently been reported. The resultant slightly soluble poly(azulene)-bromine and insoluble poly(azulene)-iodine complexes have lower electrical conductivities than the electrochemically produced polymer, 5x10 and 10 S/cm, respectively. Removal of soluble oligomers from the former leads to a slight improvement of the electrical conductivity. [119,127]. 

The insulating oligomers were reacted with iodine to create a new, cation-radical salt structure of high conductivity. The crystal structure of the iodine complex of N,N -diphenyl-p-phenylene diamine (PPAa)cI> 2 partially resolved by Huml and... 

The results of this study lead to the conclusion that poly(acetylene) oxidized by iodine essentially consists of three different components unreacted bulk polymer, iodine covered surfaces and/or amorphous regions containing iodine and a metallic conducting polymer-iodine complex salt structure with a new lattice composed of rearranged chains together with I -chains. The conductivity data indicated a percolation process involving the metallic conductive parts of the sample as component of a system with a complex texture. 

A lithium ion conducting solid electrolyte such as lithium iodide or lithium iodide-f alumina (33 mol%). The lithium iodide solid electrolyte is formed as a very thin film by directly contacting lithium metal with the positive electrode material, iodine, complexed with polyvinylpyridine. Such cells are only capable of discharge at a low rate (< 100 pAcm" ), at ambient temperatures but they perform excellently when only required to provide a low power, e.g. for a heart pacemaker. The lifetime in service can be many years and the shelf-life during storage is also long. 

The first report of a perylene-iodine complex with metallic conductivity was Per(l2)4 by Kao et al. [10], with values as high as 51.9 S/cm at 300 K. A broad maximum of conductivity exists at ca. 235 K (Figure 2.3). In a few samples that did not crack at lower temperatures, a gap of 0.1 eV was measured. The EPR linewidth at room temperature is 10.9 G, clearly distinguishable from the Per2(l2)3 complex. The authors indicate that spin density from EPR exhibits an activated behaviour with = 0.02 eV in the range 100-300 K, consistent with a model of a narrow band-gap semiconductor. The determination of the crystalline structure was not accomplished, but from X-ray oscillation photographs, an incommensurate structure was proposed. 

The use of the tetrachalcogenoperylene molecules such as TTP to obtain molecular conductors has been greatly limited by the low solubility of these compounds, which is much smaller than perylene in the usual solvents. Hilti et al. [120] obtained, by cosublimation of this donor and iodine, a highly conducting compound, TTP-I. 28- In this case, as opposed to the perylene—iodine complexes, the iodine composition was found to be much more stable in a... 

In the same era of the 1960s, work from Czechoslovak researchers established the concept of iodine doping for polyaniline. A conductivity of up to 1 S/cm for polyaniline-iodine complexes was obtained. ... 

Iodine is one of the most effective substances in the presence of which the conductance of phospholipid bilayers increases. Various interpretations of the results of measurements of the conductance of bilayers in the presences of the I /I systems have been the subject of discussion. A number of authors believed that in the presence of iodine electron conductance is possible in the membrane as a result of the formation of iodine complexes with phospholipids. In contrast to this view, it was claimed that only ionic conductance is possible. The impedence of bilayers in the presence of iodine was first measured by Louger et aL By measuring the impedance of bilayers it is possible to detect the motion of ions inside the membrane, during the measurement of the impedance at a sufficiently high frequency which would not give ions to pass from the membrane into the solution. the impedance of a bilayer membrane formed from egg lecithin with cholesterol in the presence of 10" MI2 in an aqueous solution, measured by Lebedev et al is given in Figs. 16a and 16b as a function of the concentration of KI added to the solution. 

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... 

The dinuclear [Fe(C5H5)(C0)2(CgH4S8-C8H4Sg)Fe(C5H5)C02] organometallic complex exhibits ligand-centered oxidation at a low potential [94]. The crystalline material that forms upon chemical oxidation with iodine contains both I3 and I5 anions and has a room temperature compressed pellet conductivity of 1.7 x 1CT4 S cm-1. 

Semiconducting black polymers characterized as 44 have been prepared via slow heating of triple-decker (allyl)nickel diborolyl triple-decker complexes.44 EXAFS studies reveal an Ni-Ni distance of 3.35 A and a powder conductivity of ca. 10-2 S cm-1. When doped with iodine or oxygen, the conductivity of these polymers... 

When sodium lignosulfonate or sulfur lignin are compounded, for instance, with iodine or bromine, complexes supposedly form (16-17). These systems are conductors with mixed ionic and electronic nature. Presumably they are charge transfer complexes, since the electronic conductivity predominates (18-19). These compounded materials form charge transfer structures (20). Water is supposed to introduce ionic conductivity to the system. Impurities affect conductivity, too (21). In any case, the main models of conductivity are probably based on the band model and/or the hopping model. 

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