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1.
Two species of iodide ions (I 3? and I 5?) are found in iodine—nylon 6 complexes. Orientation of I 5? arrays (most likely I 2/I 3? complex) along the polymer chain and I 3? ions perpendicular to the chain axis in uniaxially drawn films and in films with planar orientation suggests that there is and intrinsic relation between the direction of iodide ion arrays and nylon 6 chains. When an unoriented film of nylon 6 in the amorphous or the α crystalline form is treated with an aqueous solution of iodine—potassium iodide, the I 3? species in the resulting iodine—nylon complex lie in planes parallel to the surface of the film, and I 2/I 3? units are oriented normal to the surface of the film. The γ form obtained by desorbing the iodine from this complex shows considerable uniaxial rientation with the nylon chains oriented perpendicular to the plane of the film; this orientation is maintained during the γ to α transition. It is proposed that the iodine-induced orientation of the nylon 6 chains is due to the nucleating effects of the iodide ion species as the iodine diffuses unidirectionally into the film. 相似文献
2.
We report the preparation and X‐ray crystallographic characterization of the first crystalline homoatomic polymer chain, which is part of a semiconducting pyrroloperylene–iodine complex. The crystal structure contains infinite polyiodide I ∞δ?. Interestingly, the structure of iodine within the insoluble, blue starch–iodine complex has long remained elusive, but has been speculated as having infinite chains of iodine. Close similarities in the low‐wavenumber Raman spectra of the title compound and starch–iodine point to such infinite polyiodide chains in the latter as well. 相似文献
4.
Iodocyclization products of 2-allylthioquinoline are obtained in the form of polyiodides with different stoichiometric compositions. X-ray crystallography data are analyzed for two different crystal structures of 1-iodomethyl-1,2-dihydro[1,3]thiazolo[3,2- a]quinolinium polyiodides: triiodide C 12H 11INS +I 3 ? and complex polyiodide 2(C 12H 11INS +I 3 ? )·I 2. A comparison is made of the nonbonding interactions of dihydrothiazoloquinolinium with atoms of the triiodide anion and complex polyiodide to show the crystal structure features attributed to the participation of molecular iodine. 相似文献
5.
The synthesis and characterization of a novel class of polymeric phthalocyanines (Pc), (PcMX) n (M-Al, Ga, Cr; X?F and M-Si, Ge, Sn; X?0) of exceptional thermal stability are summarized. These materials possess a linear MX backbone surrounded by a sheath of cofacial M-centered Pc rings. (PcAlF) n and (PcGaF) n are sublimable (10 ?3mmHg,540°C and 430°C, respectively) allowing for thin film formation. Iodine-doping leading to compositions (PcMXI y) n with y ranging from 0.06 to 5.5 is reported. Thermogravimetric analysis has proven useful for iodine analyses and has revealed that the order of thermal stability with regard to loss of iodine is (PcCrFI y) n < (PcGaFI y) n< (PcAlFI y) n < (PcSioI y) n. Raman spectra point to I 3-and I 5-as the principle polyiodide species, though their relative proportions vary depending on M and doping level. Increases in the electrical conductivity by as much as 10 9 with maximum conductivities in the range of 0.01–1 ohm ?1cm ?1 result from iodine doping. Conduction appears to be thermally activated (77–300K) with an apparent activation energy of 0.04eV. It is likely that electron transport is primarily ligand based and is metal-like in character. 相似文献
6.
The photodissociation of methyl iodide in various matrices at low temperature was studied. The observed Raman spectra excited by 514.5 nm laser radiation showed that there were two different photolytically produced iodine species isolated in the matrices after illumination by a medium pressure mercury lamp. One species which was dominant at lower iodine concentrations and exhibited a progression with an ωe of 201 cm ?1, belonged to the matrix isolated iodine monomer (I 2). The other species, which was dominant at higher iodine concentrations with an ω e of approximately 180 cm ?1, belonged to the iodine aggregate ((I 2) n). Five progressions of resonance Raman or resonance fluorescence of these two species were also observed in the other matrices. The iodine aggregate in the methyl iodide matrix at 77 K was formed in a crystalline structure, while the photolytically generated iodine aggregate from CH 3I/Ar (2/3) matrix at 10 K, after illumination with a mercury lamp, was in amorphous form. The rearrangement of photolytically produced iodine aggregate in methyl iodide matrix was observed as a function of the duration of illumination. Local heating effects of the laser radiation might induce the iodine monomer to aggregate in matrices. The photodissociation mechanism of methyl iodide in matrices is also proposed. 相似文献
7.
A Three Dimensional Network of Iodide Ions and Iodine Molecules in the Crystal Structure of [Pr(Benzo-15-Crown-5) 2]I 21 Black polyhedra of [Pr(benzo-15-crown-5) 2]I 21 were grown from an ethanol / dichlormethane solution of PrI 3, benzo-15-crown-5 and I 2. The crystal structure (orthorhombic, P2 1cn, a = 1201.1(1), b = 2168.3(1), c = 2571.1(1) pm, Z = 4) is built up from sandwich like cations [Pr(benzo-15-crown-5) 2] 3+ and polyiodide anions I 213-. This unique polyiodide anion exhibits a complex connection pattern of iodide ions and iodine molecules with variable bond lengths forming a complicated network. 相似文献
8.
α-Cyclodextrin, a torus shaped molecule with a 5 Å wide central cavity, forms a number of deep green, blue and black crystals when complexed with iodine/metal iodide. In contrast, β-cyclodextrin, having a 6 Å cavity produces only one type of reddish-brown crystal, no matter what metal iodide is used. The complex (β-cyclodextrin) 2 ·KI 7·9H 2O displays space group P2 1 (pseudo- C2) with cell constants a=19.609(5), b=24.513(7), c=15.795(6)Å, β=109.50(2)°, Z=4. The crystal structure was solved in C2 on the basis of 3022 absorption corrected Cu Kα (Ni-filter) X-ray intensities and refined by full matrix least squares to R=17%. This relatively high R-factor is due to many weak reflections (pseudo- C2) and considerable disorder exhibited by water and iodine. In the complex, β-cyclodextrin adopts a ‘round’ shape with O(2)...O(3) interglucose hydrogen bonds formed and all O(6) hydroxyls pointing away from the cavity. Two molecules are arranged head-to-head to produce a dimer, and dimers are stacked such that a slightly zigzagged cylinder with a 6 Å-wide cavity is formed. In the cavity described by each dimer, an I 7 ? ion composed of I 2·I 3 ? ·I 2 units is located, with I 2 and I 3 ? perpendicular to each other. K + ions and 9 H 2O molecules are found in interstices between the β-cyclodextrin cylinders. This zigzag polyiodide contrasts with the linear form observed in the 5 Å wide α-cyclodextrin channels. It explains differences in color of the crystals and suggests that β-cyclodextrin polyiodide is not a good model for blue starch-iodine. 相似文献
9.
The reaction of iodine with the interesting mixed oxygen—nitrogen cyclic base 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (TODACOD) has been investigated spectrophotometrically in the solvent 1,2-dichloroethane. The spectra indicate the formation of the pentaiodide ion, I −5, judging from its two strong absorptions around 360 and 290 nm. Elemental analysis for the solid iodine—(TODACOD) complex indicate that the (TODACOD) base—iodine ratio is 1:3 in agreement with the ratio concluded from the photometric titration plots based on the absorptions of the formed polyiodide ion. Therefore, the formed iodine complex is formulated as [(TODACOD)I] +.I −5. The formation of the I −5 species was also confirmed by the resonance Raman spectrum of the solid product. The Raman spectrum can be explained entirely by the presence of the bent I −5 ion with C2υ structure. The vibrations of I −5 ion are ν s(II); outer, ν s(II); inner, ν as(II); outer, and ν as(II); inner and are assigned as expected at 164, 110, 137 and 87 cm −1, respectively. 相似文献
10.
Diaphragm cells have been used to measure ternary diffusion coefficients for I 2+NaI and I 2+KI in aqueous solution at 25°C. Although most of the iodine molecules are bound to iodide ions and are transported as the triiodide species [I 2(aq)+I –(aq)=I
3
–
(aq)], diffusion of the iodide salts produces relatively small countercurrent coupled flows of the iodine component. The ternary diffusivity of the iodine component in the solutions is 10 to 20% larger than the diffusivity of the triiodide species. This behavior can be understood by considering electrostatic coupling of the ionic flows. The diffusion equations for I 2+NaI and I 2+KI components are reformulated in terns of NaI 3+NaI and KI 3+KI mixed electrolyte components. 相似文献
11.
Zn−I 2 batteries stand out in the family of aqueous Zn-metal batteries (AZMBs) due to their low-cost and immanent safety. However, Zn dendrite growth, polyiodide shuttle effect and sluggish I 2 redox kinetics result in dramatically capacity decay of Zn−I 2 batteries. Herein, a Janus separator composed of functional layers on anode/cathode sides is designed to resolve these issues simultaneously. The cathode layer of Fe nanoparticles-decorated single-wall carbon nanotubes can effectively anchor polyiodide and catalyze the redox kinetics of iodine species, while the anode layer of cation exchange resin rich in −SO 3− groups is beneficial to attract Zn 2+ ions and repel detrimental SO 42−/polyiodide, improving the stability of cathode/anode interfaces synergistically. Consequently, the Janus separator endows outstanding cycling stability of symmetrical cells and high-areal-capacity Zn−I 2 batteries with a lifespan over 2500 h and a high-areal capacity of 3.6 mAh cm −2. 相似文献
12.
The reaction of 1-methyl-3-methylthio-5-phenyl-1,2,4-triazinium (MTPT) iodide with diiodine in a solution leads to monoiodide crystal structure that in excess of iodine gives the unusual tetraiodide anion with two central iodine atoms in disorder. The bonding within the anion has been characterized as I–…I2…I–; the existence of the bound iodine molecule inside has been proven by the characteristic band in experimental and calculated Raman spectra. Non-covalent interactions of MTPT in considered crystal structures are different. Monoiodide anion as a strong electron donor allows the formation of the S…I chalcogen bonds that are absent in tetraiodide structure. The features of halogen bonds within the I42– anion are also performed. 相似文献
13.
Plating battery electrodes typically deliver higher specific capacity values than insertion or conversion electrodes because the ion charge carriers represent the sole electrode active mass, and a host electrode is unnecessary. However, reversible plating electrodes are rare for electronically insulating nonmetals. Now, a highly reversible iodine plating cathode is presented that operates on the redox couples of I 2/[ZnI x(OH 2) 4?x] 2?x in a water‐in‐salt electrolyte. The iodine plating cathode with the theoretical capacity of 211 mAh g ?1 plates on carbon fiber paper as the current collector, delivering a large areal capacity of 4 mAh cm ?2. Tunable femtosecond stimulated Raman spectroscopy coupled with DFT calculations elucidate a series of [ZnI x(OH 2) 4?x] 2?x superhalide ions serving as iodide vehicles in the electrolyte, which eliminates most free iodide ions, thus preventing the consequent dissolution of the cathode‐plated iodine as triiodides. 相似文献
14.
At T < 250 K, the polyiodide inclusion complex (α-cyclodextrin) 2·Sr 0.5·I 5·17H 2O displays two separate relaxation processes due to both the frozen-in proton motions in an otherwise ordered H-bonding network and the order–disorder transition of some normal H-bonds to flip-flop ones. At T>250 K, the AC-conductivity is dominated by the combinational contributions of the disordered water network, the mobile Sr 2+ ions, the polyiodide charge-transfer interactions and the dehydration process. The evolution of the Raman spectroscopic data with temperature reveals the coexistence of four discrete pentaiodide forms. In form (I) (I ? 3·I 2 ? I 2·I ? 3), the occupancy ratio ( x/ y) of the central I ? ion differs from 50/50. In form (IIa) (I 2·I ? ·I 2) x/ y = 50/50, whereas in its equivalent form (IIb) (I 2·I ? ·I 2) * as well as in form (III) (I ? 3·I 2), x/ y = 100/0 (indicative of full occupancy). Through slow cooling and heating, the inverse transformations (I) → (IIa) and (IIa) → (I) occur, respectively. 相似文献
15.
On the Structure of Two Isothiazolium Polyiodides (C 19H 16FeNS)I 5 and (C 15H 12NS) 2I 8 By oxidation of 3‐phenylamino thiopropenones with iodine two isothiazolium polyiodides were obtained, whose structures have been determined by X‐ray structure analysis. 2‐Phenyl‐5‐ferrocenyl‐isothiazolium pentaiodide(C 19H 16FeNS)I 5 forms a layer structure with isothiazolium cations and polyiodide anions. The polyiodide layers contain pentaiodide ions I 5–, triiodide ions I 3– and iodine molecules I 2. Bis(2,5‐diphenyl‐isothiazolium) octaiodide (C 15H 12NS) 2I 8 also forms a layer structure with isothiazolium cations and polyiodide anions. The polyiodide layers are built up by octaiodide ions I 82–, pentaiodide ions I 5– and triiodide ions I 3–. 相似文献
16.
The open-circuit behavior of iodine films formed on platinum by electrooxidation of iodide was studied at rotating disk and rotating ring-disk electrodes. The potential transient and ring current transient at open circuit for cI?>0.012 M can be explained by assuming: (1) convective-diffusion controlled dissolution of the film; (2) establishment of the I 2+I ?→ I 3? equilibrium; (3) establishment of the I 2 (solid) →I 2 (solution) equilibrium. The behavior at lower concentrations of cI? suggests that convective-diffusion control is absent. 相似文献
17.
The title compound, 2C 6H 7ClN +·I ?·I 3?, crystallizes with undulating layers of chains containing alternate iodide and triiodide anions formed from iodine and the heterocyclic iodide salt. 相似文献
18.
It has been shown by electrospray ionization–ion‐trap mass spectrometry that B 12I 122? converts to an intact B 12 cluster as a result of successive stripping of single iodine radicals or ions. Herein, the structure and stability of all intermediate B 12I n? species ( n=11 to 1) determined by means of first‐principles calculations are reported. The initial predominant loss of an iodine radical occurs most probably via the triplet state of B 12I 122?, and the reaction path for loss of an iodide ion from the singlet state crosses that from the triplet state. Experimentally, the boron clusters resulting from B 12I 122? through loss of either iodide or iodine occur at the same excitation energy in the ion trap. It is shown that the icosahedral B 12 unit commonly observed in dodecaborate compounds is destabilized while losing iodine. The boron framework opens to nonicosahedral structures with five to seven iodine atoms left. The temperature of the ions has a considerable influence on the relative stability near the opening of the clusters. The most stable structures with five to seven iodine atoms are neither planar nor icosahedral. 相似文献
19.
The electrochemical behavior of iodine and iodide has been studied in AlCl 3+NaCl mixtures with compositions ranging from NaCl saturated melts to AlCl 3+NaCl (63+37 mol %) at platinum and tungsten electrodes. Iodide is oxidized in two steps to iodine and I(I); a reduction wave to iodide and an oxidation wave to I(I) are obtained in iodine solutions. The equilibrium constant for the reaction, I ?+I(I)=I 2, is 6×10 8 l mol ?1 in molten chloroaluminate melts at 175°C. 相似文献
20.
Quasi-solid-state electrolytes were fabricated with mesoporous silica SBA-15 as a framework material. Ionic conductivity measurements revealed that SBA-15 can enhance the conductivity of the quasi-solid-state electrolyte. The diffusion coefficients of polyiodide ions such as Ⅰ3ˉ and Ⅰ5ˉ which were confirmed by Raman spectroscopic measurement, were about twice larger than that of I-. The optimized photoenergy conversion efficiency of dye-sensitized solar cells (DSSC) with the quasi-solid-state electrolyte was 4.3% under AM 1.5 irradiation at 75 mW·cm^-2 light intensity. 相似文献
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