Reversibility of the doping of polyacetylene with iodine in the gas phase

The reversibility of the doping reaction with iodine of Shirakawa polyacetylene (PA) films, carried out in the gas phase, has been studied by means of electrical conductivity, i.r. and ESR measurements. As expected, the level of the doping strongly influences the rate of the back reaction, diffusion processes being involved through the various parts of the film. These processes are characterized by diffusion constants which differ by orders of magnitude. For lightly doped PA samples, it is easily possible to recover the initial characteristics of the electrical conductivity, while the optical i.r. characteristics may be recovered by heating the samples at 50°C, if both cis and trans isomers are present. For lightly doped all trans samples, this heat treatment was not necessary. The heavily doped all trans PA samples also regain their initial characteristics after brief heating, showing that the desorption of I₂ from the interior of the film needs to be thermally activated.     

ELECTRICAL CONDUCTIVITY OF IODINE DOPED POLY(PHTHALOCYANINATOSILOXANE)/PPTA BLEND FIBERS

Poly(phthalocyaninatosiloxane), [Si(Pc)O]n, with the number average degree of polymerization of about 130 was prepared by heating its monomer Si(Pc) (OH)_2, in solid state at 420℃for 42 hrs at 10~(-3) torr dynamic vacuum. The [Si(Pc)O]n powder was iodine doped with I_2-bensene solution for 48 hrs. Pure iodine doped poly(phthalocyaninatosiloxune), {[Si(Pc)O]I_y}n, fibers and {[Si(Pc)O]I_y}n/poly(p-pbenylene terephthalamide) blend fibers were wet-spun with dry nltrogen-sealed Teflon lined device. D.C. electrical conductivity of the fibers was measured by the four-probe method with an automated charge transport measurement system from 80K to room temperature. It was found that the dependence of conductivity, σ, on temperature, T, could fit a group of thermal fluctuation-induced tunnelling (TFIT) equations, and that the dependence of conductivity on volume fraction, φ, of the iodine doped {[Si(Pc)O]I_y}n could fit a group of modified percolation equations. A thrce-dimensioual composite plot of σ-1 / T-φshows that these two groups of equations match each other quite well. It has been pointed out that for the blend fibers their composition is the most important factor for both mechanical and electrical properties.     

Conductivity of I2‐Doped High trans‐1,4‐Polybutadiene

High trans‐l,4‐polybutadiene ( ?96% (trans)) was prepared by lanthanum naphthenate catalytic system. The conductivity of obtained polybutadiene doped with iodine reaches about ?100 s/cm, which is 2 orders of magnitude higher than the value reported.^4,5 During the I₂‐doping, the conjugated sequence was formed through double bond shifting reaction. According to the relationship between conductivity and temperature, conducting mechanism of doped high trans‐l,4‐polybutadiene is fit on variable range hoping (VRH) model.     

Design of anhydrous electrorheological (ER) suspensions based on I2-doped poly(pyridinium salt)

A rigid-rod aromatic poly(pyridinium salt) was synthesized and doped with iodine (I₂) for making anhydrous electrorheological (ER) fluids. The I₂-doped particles were further processed into ones having insulating skins. Dielectric properties and current densities of the suspensions containing these particles were studied to elucidate the roles of conductivity of the dispersed phase in the ER suspension. © 1994 John Wiley & Sons, Inc.     

Face‐Capped M4L4 Tetrahedral Metal–Organic Cage: Iodine Capture and Release,Ion Exchange,and Electrical Conductivity

An M⁴L₄ type metal–organic cage (MOC‐19) has been synthesized from the one‐pot reaction of tri(pyridinylmethylene)phenylbenzeneamine (TPBA) with hydrated Zn(ClO₄)₂ under mild conditions and characterized by single‐crystal X‐Ray diffraction. Iodine capture studies show that the porous crystals of MOC‐19 exhibit a versatile behavior to accumulate iodine species not only in vapor (for I₂) but also in solution (for I₂ and I₃^?), and anion‐exchange experiments indicate the capacity to extract IO₃^? anions from aqueous solution. Enrichment of iodine species from KI/I₂ aqueous solution proceeds facilely, revealing a pseudo‐second‐order kinetics of I₃^? adsorption. Furthermore, the electrical conductivity of MOC‐19 single crystals could be significantly altered by I₂ inclusion.     

Beiträge zur Kristallchemie und zum thermischen Verhalten von wasserfreien Phosphaten. XXXIII [1] In2P2O7, ein Indium(I)‐diphosphato‐indat(III) und In4(P2O7)3 — Darstellung,Kristallisation und Kristallstrukturen

Contributions on Crystal Chemistry and Thermal Behaviour of Anhydrous Phosphates. XXXIII [1] In₂P₂O₇ an Indium(I)‐diphosphatoindate(III), and In₄(P₂O₇)₃ — Synthesis, Crystallization, and Crystal Structure Solid state reactions via the gas phase lead to the new mixed‐valence indium(I, III)‐diphosphate In₂P₂O₇. Colourless single crystals of In₂P₂O₇ have been grown by isothermal heating of stoichiometric amounts of InPO₄ and InP (800 °C; 7d) using iodine as mineralizer. The structure of In₂P₂O₇ [P2₁/c, a = 7.550(1) Å, b = 10.412(1) Å, c = 8.461(2) Å, b = 105.82(1)°, 2813 independent reflections, 101 parameter, R1 = 0.031, wR2 = 0.078] is the first example for an In⁺ cation in pure oxygen coordination. Observed distances d(In^I‐O) are exceptionally long (d_min(In^I‐O) = 2.82 Å) and support assumption of mainly s‐character for the lone‐pair at the In⁺ ion. Single crystals of In₄(P₂O₇)₃ were grown by chemical vapour transport experiments in a temperature gradient (1000 → 900 °C) using P/I mixtures as transport agent. In contrast to the isostructural diphosphates M₄(P₂O₇)₃ (M = V, Cr, Fe) monoclinic instead of orthorhombic symmetry has been found for In₄(P₂O₇)₃ [P2₁/a, a = 13.248(3) Å, b = 9.758(1) Å, c = 13.442(2) Å, b = 108.94(1)°, 7221 independent reflexes, 281 parameter, R1 = 0.027, wR2 = 0.067].     

Determination of total iodine in samples with an organic matrix by solid-phase spectrophotometry

A solid-phase spectrophotometry method is proposed for determining total iodine in samples with an organic matrix. The method involves the sorption of I₂ formed in oxidation of iodide with oxone (active ingredient potassium peroxomonosulfate) by polyurethane foams, followed by the registration of the adsorbent absorbance at 360 nm. Sample preparation includes treatment with an aqueous methanolic solution of tetramethylammonium hydroxide followed by thermostation at 90 ± 2°C for 3 h. The detection limit for iodine calculated using the 3s-test is 0.03 μg in a sample aliquot portion of ≤8 cm³. The relative standard deviation is 8–12% for iodine concentration in the range 0.3–5.0 μg/g.     

Crystal structure and electrical conductivity of nickel 6, 13-di (p-tolyl)-5, 14-dihydrodibenzo [b,i]-1,4,8,11-tetraaza [14]annulene Iodide (Ni (dtdbtaa)I2.58)

Single crystals of the title compound are monoclinic, space group P2₁/n with two formula units per cell of the following dimensions: a = 18.209, b = 19.076, c = 4.075 Å, β = 92.43°. The crystals show metallic conductivity along the needle axis from room temperature down to ca. 180 K , the maximum conductivity at room temperature being 455 (Ω cm)^?1. The unoxidized (iodine free) parent compound crystallizes n the monoclinic space group P2₁/c with 2 molecules per cell of dimensions: a = 4.988, b = 20.192, c = 11.871 Å, β = 94.41°.     

A COMPARISON OF POLYACETYLENES PREPARED WITH VARIOUS CATALYST SYSTEMS

A comparison of polyacetylenes (PA) prepared with rare earth(Ln) and titanium(Ti) basedcatalyst systems in regard to the isomerization rate, conductivity and doping behaviour is presented.It is found that PA synthesized with Ln-catalyst showed the lower isomerization rate than Ti-PA.Room temperature conductivity of I_2-doped Ln-PA is higher than that of Ti-PA under the sameconditions, this might related to the uniform conjugation length of Ln-PA. The difference in thedoping behaviors was observed for cis and trans PA films. and the complicated doping behavioursof cis-PA could be attributed to the simultaneously occurring isomerization reaction during doping.     

Semiconducting poly(dicyanoacetylenes)

Poly(dicyanoacetylene) (PDCA) has been synthesized and characterized. The pristine polymer has EPR g-value, linewidth, unpaired spin concentration, spin—spin relaxation time (T₂), and room temperature dc conductivity (σ_RT) very similar to those of pristine cis-polyacetylene (PA), but shorter spin—lattice relaxation time (T₁). Saturation doping with iodine has little effect on most EPR characteristics of the polymer except for a slight increase in T₁. The doped PDCA has σ_RT value of only 5 X 10^-9 (Ω cm)^-1, indicating either low carrier concentration and/or carrier mobility. Partial cyclization of the nitrile groups by heating at 400°C of PDCA produces l-PDCA with significant increases in unpaired spin concentration and σ_RT but marginal effects on other properties. Saturation doping of l-PDCA with iodine increases σ_RT to 7 × 10^-3 (Ω cm)^-1 without appreciable changes in EPR characteristics. The dopants in both polymers can be removed by evacuation indicating only weak charge transfer interactions. The possible stereoelectronic contribution toward the property differences between the PDCA polymers and PA are discussed.     

Pb5I2P28, $^{1}_{\infty}\rm [PbP_{14}]{\rm ^{2-}}$ Strands Coordinated to a Unique [Pb3I2]4+ Unit

Pb₅I₂P₂₈ is the first compound containing a former unseen [P₃I₂]⁴⁺ unit, connecting two crystallographically independent adjacent [PbP₁₄]^2? polyphosphide strands. The polyanion substructure is closely related to the one realized in the HgPbP₁₄ structure type, with a homo‐nuclear coordination of the cations to the polyanions. It has been prepared by using the mineralizator concept for polyphosphides from the elements and PbI₂ as the mineralizator species. The new polyphosphide has a pronounced tendency to form easy cleavable, needle shaped crystals featuring massive stacking vaults. Nevertheless, a single crystal structure determination was possible from inter‐grown crystals. Pb₅I₂P₂₈ crystallizes monoclinically in the space group P2₁/n (No. 14) with lattice parameters of a = 9.792(2), b = 17.717(2), c = 19.191(3) Å, β = 96.39(1)°, V = 3308.6(8) ų. Depending on the preparation route, the aspect ratio of the needle shaped crystals can be varied.     

Dilation and plasticization of polystyrene by carbon dioxide

We have used an optical interference technique to measure the dilation of polystyrene films in the presence of carbon dioxide or helium at pressures up to 20 atm. Dilation isotherms (plots of dilation versus gas pressure at constant temperature) were obtained for three samples of polystyrene which had widely differing molecular weights. The dilation isotherms have the same general shape as sorption isotherms, which means that all of the sorbed gas molecules contribute to volume dilation and non can be thought of as occupying molecular-sized voids in the polymer. Using sorption results from the literature we show that the partial molar volume of CO₂ at 35°C is about 39 cm³ mol^?1 and appears to be independent of polystyrene molecular weight. For a polystyrene sample with M_n = 3600, the partial molar volume of sorbed CO₂ increases to 44 and 50 cm³ mol^?1 at 45 and 55°C, respectively. The sorption of CO₂ in polystyrene is shown to depress the glass transition temperature of the mixture, consistent with theoretical predictions. The shape of the dilation and sorption isotherms are consistent with the depression of the glass transition temperature.     

DC Electrical Conductivity of Polymercaptobenzothiazole Disulfide Copper Complex

Polymercaptobenzothiazole disulfide-copper complex PMBTS-Cu has been synthesized by reacting 2-mercaptobenzothiazole disulfide with CuCl₂ in absolute ethanol and dimethyl sulfoxide (DMSO) under reflux for 24 h. PMBTS-Cu has been characterized by several techniques using electronic spectra, elemental analyses, FTIR spectroscopy, and its solubility has been investigated. DC electrical conductivity variation with temperature, in the range 300–500 K, after annealing for 24 h at 100°C, and doping with different ratios of I₂, is determined for comparison. Doping was done in two ways: by mixing and chemically. Activation energies were calculated and the results were interpreted using the band energy model. DC electrical conductivity of I₂doped PMBTS-Cu complex increased with increasing temperature due to the variation of the carrier concentration with temperature as in the case of semiconductors. PMBTS-Cu complex has a copper ion in its backbone and copper salt is known to be a good dopant. Thus, these materials are doped internally, so the doped polymer-Cu complex are only one or two orders of magnitude higher in DC electrical conductivity than the annealed state. However, the energy gap is very small, which suggests suitability in applications like photovoltaic cells.     

Preparation of a novel polymer gel electrolyte based on N-methyl-quinoline iodide and its application in quasi-solid-state dye-sensitized solar cell

Using poly(acrylonitrile-co-styrene) as polymer host, 1,2-propanediol carbonate, dimethyl carbonate and ethylene carbonate as mixture solvent, N-methyl-quinoline iodide and iodine as the source of I⁻/I₃ ⁻, a novel polymer gel electrolyte with ionic conductivity of 5.12 × 10⁻³ S· cm⁻¹ at 25°C was prepared by sol-gel and hydrothermal methods. Based on the polymer gel electrolyte, a quasi-solid-state dye-sensitized solar cell was fabricated. The solar cell possess better long-term stability and light-to-electrical energy conversion efficiency of 4.04% under irradiation of 100 mW· cm⁻². The influences of polymer host, solvent, N-methyl-quinoline iodide and temperature on ionic conductivity of the polymer gel electrolyte and the performance of the dye-sensitized solar cell was discussed.     

Der chemische Transport von FeP2 und FeP4 mit lod

Chemical Transport of FeP₂ and FeP₄ with Iodine Experiments on the chemical transport of FeP₂ and FeP₄ with iodine are discussed, considering the gaseous molecules I₁, I₂, FeI₂, Fe₂I₄, FeI₃, Fe₂I₆, PI₃, P₂I₄, P₄, P₂, and P. Thermodynamic calculations give δH°(298) = 56.322 kcal and ΔS°(298) = 39.5 cal/K for the reaction FeP_2,f + I₂ = FeI₂ + 0.5 P₄ and δG°(923) = 35.8 kcal for the reaction FeP_4,f + I₂ = FeI₂ + P₄.     

Bis(methyltri‐o‐tolylphosphonium) octaiodide

In the crystal structure of the title compound, 2C₂₂H₂₄P⁺·I₈²⁻, the I₈²⁻ anion is located on a crystallographic inversion centre and consists of two tri‐iodide anions linked by di‐iodine at angles of 89.92 (4)° to form a planar `Z'‐shaped dianion. The octaiodides are linked via long‐range interactions [3.877 (11) Å] into infinite polyiodide ribbons. This is the first example of a structure containing an [(o‐tolyl)₃PMe]⁺ cation, and the C_Me—P—C—C_Me torsion angles of −54.0 (11), −51.3 (11) and −48.2 (11)° indicate that the configuration is exo₃.     

Conducting polymers VIII: Optical and electrical conductivity of poly(bis-m-phenylenediaminosulphoxide)

Poly(bis-m-phenylenediaminosulphoxide) (PPDS) was prepared from Michael addition of N,N′-bis-sulphinyl-m-phenylenediamine and m-phenylenediamine. The prepared PPDS was then doped with iodine. PPDS was characterized by FTIR, ¹H-NMR, elemental microanalysis, thermogravimetric analysis (TGA), UV-visible absorption and fluorescence emission spectra. Thermal gravimetric analysis TGA showed that PPDS is thermally stable up to 179 °C. Electronic transitions showed main absorption peak at λ = 340 nm and two emission peaks at 460 and 490 nm. The behavior of both dc and ac electrical conductivities of PPDS were studied. The direct current electrical conductivity (σ_dc) and the alternating current electrical conductivity (σ_ac) were enhanced by the physical doping of I₂ in the polymer matrix. The conduction mechanisms for dc and ac electrical conductivities have been investigated.     

Two New Modifications of [P(C6H5)4]2[Cu2I4]

Single crystals of two new modifications of [P(C₆H₅)₄]₂[Cu₂I₄] were obtained by reaction of granulated copper with iodine and [P(C₆H₅)₄]I in dry acetone under nitrogen atmosphere. They crystallise monoclinically, space group P2₁/n (No. 14), a = 11.550(6), b = 7.236(2), c = 27.232(13) Å, β = 98.13(3)°, V = 2253(2) ų, and Z = 2 ([P(C₆H₅)₄]₂[Cu₂I₄]-C), and space group Cc (No. 9), a = 17.133(5), b = 15.941(5), c = 18.762 (6) Å, β = 114.02(1)°, V = 4681(3) ų, and Z = 4 ([P(C₆H₅)₄]₂[Cu₂I₄]-D), respectively. In these compounds the [CuI₂]^? anions form dimers di-μ-iodo-diiodocuprate(I), which are either planar ( C ) or folded ( D ).     

Phosphaniminato-Komplexe des Iods. Synthese und Kristallstrukturen von Ph3PNIO2 und Ph3PNSiMe3 · I2

Phosphoraneiminato Complexes of Iodine. Syntheses and Crystal Structures of Ph₃PNIO₂ and Ph₃PNSiMe₃ · I₂ Ph₃PNIO₂ has been prepared as yellow crystals by the reaction of Ph₃PNSiMe₃ with I₂O₅ in boiling acetonitrile, whereas the molecular complex Ph₃PNSiMe₃ · I₂ is formed as brown crystals by the reaction of Ph₃PNSiMe₃ with iodine in acetonitrile solution. Both complexes were characterized by crystal structure determinations. Ph₃PNIO₂: Space group P2₁/n, Z = 4, 2 858 observed unique reflections, R = 0.039. Lattice dimensions at 19°C: a = 972.8(2), b = 1 743.4(3), c = 1 073.7(2) pm, β = 115.46(3)°. The compound forms monomeric molecules with pyramidal geometry at the iodine atom. The bond angle PNI (126.9°) is unusually small; the PN bond length of 159.2 pm corresponds with a double bond. Ph₃PNSiMe₃ · I₂: Space group P1 , Z = 2, 3 560 observed unique reflections, R = 0.033. Lattice dimensions at 19°C: a = 941.2(2), b = 1 041.7(2), c = 1 287.4(3) pm, α = 78.34(1)°, β = 72.00(2)°, γ = 86.08(2)°. The compound forms monomeric molecules, in which the I₂ molecule and the nitrogen atom of the phosphoraneimine molecule realize a linear N? I? I axis with a bond length N? I of 243.2 pm.     

Electrical transport properties of pristine and iodine doped polyetherimides

Electrical conduction behavior of pristine and iodine doped polyetherimides(PEI) has been investigated under both transient and steady state conditions in the operating temperature range 50-200℃at various electric fields of 12-60 kV/cm.The transient currents show the hyperbolic decay character,and the decay exponent p(a measure of current decay rate) decreases with temperature(7) and doping concentration.The origin of transient currents has been attributed to the dipolar nature of carbonyl((?)C=O) groups...