Iodine Chains Research Articles

Stable double helical iodine chains inside single-walled carbon nanotubes

The helicity of stable double helical iodine chains inside single-walled carbon nanotubes (SWCNTs) is studied by calculating the systematic interaction energy. Our results present clear images of stable double helical structures inside SWCNTs. The optimum helical radius and helical angle increase and decrease with increasing diameter, respectively. The tube's diameter plays a leading role in the helicity of encapsulated structures, while the tube's chirality may induce different metastable structures. This study indicates that the observed double helical iodine chains in experiments are not necessarily the optimum structures, but may also be metastable structures.

Inside Back Cover: Infinite Polyiodide Chains in the Pyrroloperylene–Iodine Complex: Insights into the Starch–Iodine and Perylene–Iodine Complexes (Angew. Chem. Int. Ed. 28/2016)

Inside Back Cover: Infinite Polyiodide Chains in the Pyrroloperylene–Iodine Complex: Insights into the Starch–Iodine and Perylene–Iodine Complexes (Angew. Chem. Int. Ed. 28/2016)

Infinite Polyiodide Chains in the Pyrroloperylene-Iodine Complex: Insights into the Starch-Iodine and Perylene-Iodine Complexes.

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.

Infinite Polyiodide Chains in the Pyrroloperylene–Iodine Complex: Insights into the Starch–Iodine and Perylene–Iodine Complexes

AbstractWe 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.

Crystal structure of 1-ethyl-5-iodoindolin-2-one

In the title indolinone derivative, C10H10INO, all the non-H atoms, except the terminal methyl C atom, are almost coplanar. The mol-ecules are arranged into columns extending along the a-axis direction and inter-act with the mol-ecules in adjacent columns via C-H⋯O hydrogen bonds [H⋯O distance = 2.57 (3) Å] and I⋯I short contacts of 3.8986 (3) Å. A one-dimensional zigzag iodine chain along the a axis is apparent between two neighbouring columns.

Structural transformation of confined iodine in the elliptical channels of AlPO4-11 crystals under high pressure

Iodine molecules confined in the elliptical nanochannels of AlPO4-11 crystals can only rotate in the plane passing through the major axis of the elliptical cross-section due to size confinement. This leads to different dynamic behaviors of iodine from those confined in round channels of AlPO4-5 crystals under ambient conditions. In this work, we use high pressure technology to manipulate the nanoscaled iodine species confined in the elliptical channels of AlPO4-11 crystals. In situ polarized Raman measurements and theoretical simulations have been carried out to study the topological geometry of the confined iodine species upon compression. It was found that the population of iodine chains could significantly increase at the expense of standing iodine molecules under pressure up to 6 GPa, due to the pressure-induced rotation of standing iodine molecules. Besides, the contraction of the host framework along the channel axis favors the formation of iodine chains and strengthens the interaction of neighbouring molecules in a chain, consequently leading to a frequency redshift of the corresponding Raman mode. The different transformation dynamics of the confined iodine in AlPO4-11 crystals upon compression, compared to those in round channels of AlPO4-5 crystals, have been discussed in terms of the unique nanochannels that offer the quasi two-dimensional nanoscaled confinement environment.

Pressure-Driven Topological Transformations of Iodine Confined in One-Dimensional Channels

The behavior of molecules and molecular chains confined in 1D nanochannels imposed by external interactions is a problem of fundamental interest. Here, we report structural manipulation of iodine confined inside zeolite (AFI) nanochannels by the application of high pressure. Structural transformations of the confined iodine under pressure have been unambiguously identified by polarized Raman spectroscopy combined with theoretical simulation. The length of the iodine chains and the orientation and intermolecular interaction of the confined iodine have been tuned at the molecular level by applied pressure. Almost all the confined iodine can be tuned into an axially oriented state upon compression, favoring the formation of long chains. The long iodine chains can be preserved to ambient pressure when released from intermediate pressures.

Dual-ligand approach to synthesize a new 3-D heterometallic framework consisting of dysprosium–carboxyl belt and inorganic copper–iodine chain

A novel three-dimensional (3-D) Dy(III)–Cu(I) heterometallic polymer, [Dy 2 (pca) 2 (npa) 2 (H 2 O) 3 ](Cu 2 I 2 ) ( 1 , pca = 2-pyrazinecarboxylic acid, npa = 1,8- naphthalenedicarboxylic acid), has been synthesized by hydrothermal reactions of Dy 2 O 3 , CuI, 2-pyrazinecarboxylic acid, 1,8-naphthalene anhydride in water in the presence of HClO 4 . Compound 1 has been characterized by elemental analysis, infrared spectroscopy, powder X-ray diffraction and single-crystal X-ray diffraction analysis, respectively. The thermal stability and luminescence property of compound 1 have also been studied. Single crystal X-ray diffraction analysis reveals that compound 1 contains two distinct units of 1-D Dy–carboxyl belt and Cu–I chain. The two types of 1-D units are further linked via pca ligands to give a heterometallic Dy–Cu framework. A novel three-dimensional (3-D) Dy–Cu heterometallic polymer 1 contains two distinct units of 1-D Dy–carboxyl belt and Cu–I chain. The two types of 1-D units are further linked via pca ligands to give a heterometallic Dy–Cu framework. The two different types of 1-D building units are rarely observed in the reported heterometallic framework. • Compound 1 is a 3-D Dy–Cu heterometallic framework. • Compound 1 contains two distinct units of 1-D Dy–carboxyl belt and Cu–I chain. • Compound 1 is synthesized by dual-ligand approach.

Visible‐Light Hypervalent Iodide Carboxylate Photo(trifluoro)methylations and Controlled Radical Polymerization of Fluorinated Alkenes

IFAB-ulous trifluoromethylation: (CX3COO)2I(III) h (X=F, H) and (CH3COO)3I(V)(C6H4COO) are introduced as CX3·/CX3I precursors for metal-free, visible-light, radical (trifluoro)(iodo)methylations of alkenes, illustrated by their use as photoinitiators for the controlled radical polymerization of vinylidene fluoride with external (I(CF2)6I) and in situ generated (CF3I) iodine chain transfer agents, and for block copolymer synthesis.

FTIR Spectra of Hydrogen-Bonded Inclusion Compounds of Iodine

The inclusion compounds of iodine such as α-cyclodextrin-KI-I2-4H2O, β-cyclodextrin-KI-I2-H2O, and amylose-iodine are hydrogen bonded with dyes such as Para red, Congo red, Direct red, Bismark brown, Trypan blue, and Evans blue. Hydrogen bonding of these with dyes containing O–H and N–H occurs in glucosidic oxygen atoms or O–H groups of the polysaccharides. Excitons are emitted and absorbed by the electrons along the iodine chains as revealed by the analysis, which reduces band gap along the polyiodide chains.

Electronic band structure of helical iodine chains

AbstractThe electronic band structure of helical iodine chains was calculated within the empirical tight binding approach. The screw symmetry of the system was used to reduce the size of the problem to a single atom with four atomic orbitals. The overlap parameters were fitted to reproduce the DFT results for a linear iodine chain. The obtained results for helical chains have shown the energy band splitting due to the overlap between p orbitals introduced by the structure twisting. The splitting magnitude depends on the pitch of the helix.

High fish consumption in French Polynesia and prenatal exposure to metals and nutrients.

French Polynesians consume high quantities of fish and are therefore exposed to seafood-related contaminants such as mercury (Hg) or lead (Pb) and nutrients such as iodine, selenium and long chain polyunsaturated fatty acids (LC-PUFAs). As the developing foetus is sensitive to contaminants and nutrients, a cross-sectional study was conducted in French Polynesia in 2005-2006 to assess prenatal exposure to contaminants and nutrients through fish consumption. Two hundred and forty one (241) delivering women originating from all islands of French Polynesia were recruited and agreed to answer questions on fish consumption and gave permission to collect umbilical cord blood for metals and nutrients analyses. All parameters were found in high concentrations in cord blood samples except for lead. Mercury concentrations averaged 64.6 nmol/L (or 13 microg/L) with values ranging from 0.25 to 240 nmol/L. Of the sample, 82.5% had Hg concentrations above the US-EPA blood guide-line of 5.8 microg/L. Tuna was the fish species which contributed the most to Hg exposure. High selenium and LC-PUFAs may counterbalance the potential risk of prenatal exposure to Hg in French Polynesia. Due to the high fish consumption of mothers, Polynesian newborns are prenatally exposed to high doses of mercury. Although selenium and omega-3 fatty acids may counteract mercury toxicity, informing pregnant women on both the mercury and nutrient content of local fish species is important.

Polymorphic Structures of Iodine and Their Phase Transition in Confined Nanospace

Atomic chains and crystal of iodine were successfully generated in a controlled manner inside single-walled carbon nanotubes (SWNTs). The structure is strongly dependent on the diameter of SWNTs; the single, double, and triple helical structures became quite stable when the diameter of SWNTs matches the certain size. More than three chains of iodine are not very stable, and they often crystallize inside the carbon nanotube when the diameter is larger than 1.45 nm. The crystallization or phase transition in a confined nanospace is thus directly observed, and there is indeed a critical size of the hollow nanospace for the stable formation of the atomic chains of iodine.

EXAFS investigations of iodine-doped carbon nanotubes

We report an x-ray absorption fine structure study at the iodine-K edge of the local structure in iodine-doped carbon nanotubes. The iodine-carbon host interaction is shown to be weaker in multiwalled carbon nanotubes (MWNTs) than in single-walled carbon nanotubes (SWNTs). Iodine species are only localized at the surface of the external tube for MWNTs, whereas iodine species enter inside SWNTs. For doped SWNTs, both the experimental and the theoretical EXAFS spectra allow us to establish the structure of the iodine chain as disordered pentaiodide at the saturation level.

Diffuse scattering and short-range order in uranium iodine phthalocyanine [U1-xPc(2)]I2-y and the X-ray structure analysis of crystals with diffuse superstructure reflections.

Crystals of uranium iodine phthalocyanine present an example of a disordered commensurate modulated structure of the intergrowth type. The short-range order of both uranium ions and iodine chains [I(3)(-)](n) has been analysed by Reverse Monte Carlo (RMC) simulation of X-ray diffuse scattering. The diffraction pattern of uranium iodine phthalocyanine contains diffuse superstructure reflections. In the routine crystal structure analysis diffuse superstructure reflections may be either omitted or measured and classified along with other Bragg reflections. The crystal structure of uranium iodine phthalocyanine is an example of such ambiguity. The crystal structures of two specimens of [U(1-x)Pc(2)]I(2-y) with slightly different composition have been published in the literature with different space groups and unit cells. We have shown that the structure of both specimens differs only in the degree of short-range order and is isostructural with [YbPc(2)]I(2). We have also shown that while the omission of diffuse reflections results in the average crystal structure, the treatment of these reflections as normal Bragg reflections is incorrect and produces the structure averaged over a limited small range.

Diffuse X-ray scattering and reverse Monte Carlo simulation of the short-range order in ytterbium iodine phthalocyanine [YbPc(2)]I(2).

Iodine-doped ytterbium phthalocyanine, C(64)H(32)N(16)YbI(2), [YbPc(2)]I(2) (YPI), presents an example of a disordered modulated crystal structure of the intergrowth type. The short-range order in YPI has been studied at ambient temperature by the diffuse X-ray scattering technique. Both Yb and I atoms are disordered. In a unit cell of the average structure, the Yb atoms occupy two positions, 1/2, 1/2, 1/4 or 1/2, 1/2, 3/4, with occupancy 0.5. In the neighbouring unit cells in the (001) plane there is, however, a strong tendency towards an alternating distribution of ytterbium in positions shifted by Delta z = 1/2. The crystal structure of YPI consists of one-dimensional columnar stacks of [YbPc(2)(2/3+)](n) and of linear iodine chains [I(3)(-)](n). The modulation is commensurate since the period c(I) of iodine chains [I(3)(-)](n) in the [001] direction is equal to one-half of the period c of the [YbPc(2)(2/3+)](n) stacks. In the crystal structure, each stack of [YbPc(2)(2/3+)](n) may occur in two settings shifted by c/2 and each iodine chain in three settings shifted along [001] by one-third of the period c(I). The short-range order of iodine chains distributed over three settings results in a complicated pattern. Iodine chains of the same setting tend to form ribbons perpendicular to <100> and running along [001].

Synthesis and structural investigation of iodine doped uranium diphthalocyanine-UPc 2I 2

Partially oxidized by iodine uranium(IV) diphthalocyanine, U(C 32H 16N 8) 2I 2, (UPc 2I 2) was obtained by the direct reaction of pure powder uranium with 1,2-dicyanobenzene under a stream of iodine. The compound crystallizes in a space group P4/ nnc of the tetragonal system with two molecules in a unit cell. The U atoms in the crystal are disordered onto two different crystallographic positions ( 2a and 2b) in ratio of 1:5. The crystal is composed of partially oxidized UPc 2 units, which form a pseudo monodimensional stack along [001] direction. The stacks are surrounded by disordered chains of iodine, identified as I 3 − ions by Raman spectroscopy. The EPR measurement exhibits a single signal at g=2.0013, the spin concentration (0.15 spins per UPc 2 molecule) indicates spin–spin coupling between the monooxidized Pc − ring within the columns.

Synthesis and X-ray characterization of the iodine-doped metallodiphthalocyanine UPc 2I 5/3

Partially oxidized by iodine, uranium(IV) diphthalocyanine, U(C 32H 16N 8) 2I 5/3, (UPc 2I 5/3), was obtained by the direct reaction of pure powder uranium with 1,2-dicyanobenzene under a stream of iodine. The compound crystallizes in a space group D 4h 2 − P4/mcc of the tetragonal system with one molecule in a unit. The two heavy atoms (U and I) are disordered in the crystal. The crystal is composed of partially oxidized UPc 2 units, which form a pseudo monodimensional stack along the [001] direction. The stacks are surrounded by disordered chains of iodine, identified as I 3 − ions by Raman spectroscopy. The EPR measurements ( g=2.0014) confirm that phthalocyaninato ligand is partially oxidized.

Reversible Intercalation of Charged Iodine Chains into Carbon Nanotube Ropes

We report intercalation of charged polyiodide chains into the interstitial channels in a single-wall carbon nanotube (SWNT) rope lattice, suggesting a new carbon chemistry for nanotubes, distinctly different from that of graphite and ${\mathrm{C}}_{60}$. This structural model is supported by results from Raman spectroscopy, x-ray diffraction, $Z$-contrast electron microscopy, and electrical transport data. Iodine-doped SWNTs are found to be air stable, permitting the use of a variety of techniques to explore the effect of charge transfer on the physical properties of these novel quantum wires.

Resonance Raman Spectra and Crystal Structure of Lithium Phthalocyaninate(1-) Iodine: a Realistic Model for the Starch-Iodine Complex

The lithium phthalocyaninate(1-) iodine inclusion complex [( Lipc −)· I ], prepared by the reaction of anhydrous lithium iodide with molten 1,2-dicyanobenzene, crystallizes tetragonally in the space group P4/mcc with a = 14.057(3) Å, b = 6.397(1) Å, V = 1264.0(4) Å3, Z = 2. Lithium is in a crystallographically imposed strictly square planar coordination geometry with a Li - N distance of 1.940(7) Å. Linear chains of equidistant iodine atoms are segregated from adjacent metal-over-metal stacks of the planar lithium phthalocyaninate(1-) molecules, which are staggered by 40.2(5)°. Resonance Raman spectra have been studied in comparison with those of the starch-iodine complex [(starch)·I]. The identity of the iodine chromophore in both complexes is essentially the same. It consists of an iodine chain in a hydrophobic environment. Its character is predominately ‘aliphatic’ in [(starch)·I] and ‘aromatic’ in [( Lipc −)· I ].