Perrhenate Ion Research Articles

Proton Presence and Motion in Rhenium-Oxide Films and Their Application to Liquid-Crystalline Cells

Disordered solid phases, containing appreciable amounts of hydrogen ions, are grown at the surface of rhenium oxide crystals, because of the high reactivity of this compound with ambient moisture. To investigate such phenomena, a comparative study is performed on ground powder and thermally evaporated or sputtered films using x-ray diffraction and micro-Raman spectroscopy. Two types of solid phases were found in the films: HxReO3 distorted perovskite structures, based on corner-sharing ReO6 octahedra as in the bulk crystals, and ordered HReO4 crystalline structures, based on tetrahedral perrhenate ions. The complex impedance measurements on ReO3 films support the hypothesis of mobile hydrogen ions in such defective films. Moreover, this relevant protonic conductivity allows the application of these films as active layers inserted into asymmetric nematic liquid-crystalline cells to rectify the electro-optical response of such devices, with performances quite similar to previously studied oxides such as WO3.

Tetra-μ-acetamidato-κ4N:O;κ4O:N-diaquadirhodium(II,III) perrhenate

In the title compound, [Rh2(C2H4NO)4(H2O)2][ReO4], the cation lies on an inversion center and the anion on a twofold axis. The cations are connected two-dimensionally by O—H⋯O and N—H⋯O hydrogen bonding. Hydrogen bonds to perrhenate ions connect the two-dimensional sheets.

Sorption of sulfate ions onto hematite studied by attenuated total reflection-infrared spectroscopy: Kinetics and competition with other ions

In this paper, after a short discussion about the use of attenuated total reflection-infrared spectroscopy (ATR-IR) to study sorption of inorganic ions onto iron oxides, results of ATR-IR spectroscopy of surface complexes adsorbed on hematite are presented. Kinetics of sorption of sulfate ions was followed, showing an equilibrium after half an hour. The infrared band was assigned to a monodentate surface complex with a low contribution of a bidentate complex with help of second-derivative spectral analysis. The effect of several ions ( SeO 4 2 - , ReO 4 - , UO 2 2 + ) after sorption of sulfate (10 μM) was investigated. Selenate ions (10–100 μM) were shown to compete with sulfate ions, while perrhenate ions (1–100 μM) did not desorbed sulfate complexes. Experiments were also carried out in the hematite–sulfate (10 μM)–uranyl (10 μM) system, but no ternary complex was observed.

Novel and Efficient Preparation of Precursor [188Re(OH2)3(CO)3]+ for the Labeling of Biomolecules

A novel and efficient method for preparing 188Re(I) tricarbonyl precursor [188Re(OH2)3(CO)3]+ has been developed by reacting [188Re]perrhenate with Schibli's kit in the presence of borohydride exchange resin (BER) as a reducing agent and an anion scavenger. The precursor was produced in more than 97% yield by reacting a solution of tetrahydroborate exchange resin (BER, 3 mg), borane-ammonia (BH3.NH3, 3 mg), and potassium boranocarbonate (K2[H3BCO2], 3 mg) in 0.9% saline with a solution of sodium perrhenate (Na188ReO4) with up to 50 MBq and concentrated phosphoric acid (85%, 7 microL) at 60 degrees C for 15 min. HPLC and TLC revealed 0% unreacted [188Re]perrhenate ion and <3% of colloidal 188ReO2. Since the precursor is produced with high radiochemical purity and labeling efficiency under the milder conditions than those required for the conventional reducing agents, the latter can be replaced.

Changes in the local symmetry of the ReO 4 − anion near the melting point of alkali metal perrhenates

Raman spectra of alkali metal perrhenates in the vicinity of the crystal-melt phase transition have been studied. A premelting region characterized by high-temperature activation of the reorientational mobility of perrhenate ions has been revealed.

Column Performance Testing of SuperLig® 639 Resin with Simulated Hanford Waste Supernates: Identification of the Primary Sorbing Species and Detailed Characterization of Their Desorption Profiles

:Several benchscale column tests (resin bed volume ≤75 mL) have been conducted with SuperLig® 639 resin and simulated U.S. Department of Energy tank waste supernates. Rhenium (surrogate for technetium in actual waste samples) breakthrough profiles were determined for three simulant compositions, which are representative of the basic waste categories requiring treatment in the Hanford River Protection Project Waste Treatment Plant. Considerable loading performance variability was observed between the three waste types, although the resin is effective at rhenium removal from each solution. Careful and frequent analysis during elution studies conducted at the conclusion of the column loading tests confirmed that sodium nitrate and sodium perrhenate ion pairs are primary sorbing species on SuperLig® 639 resin. Furthermore, it was discovered that potassium nitrate and potassium perrhenate salts are significant competitors for sorption sites on the resin. Successive desorption profiles were identified for all four salt species during elution tests. Integration of the desorption profiles revealed that the resin is selective for removal of the potassium salts over the sodium salts.

Microwave Assisted Facile One-Pot Synthesis of 188Re-Complex Using a Tetrahydroborate Exchange Resin. A Bifunctional Chelating Agent for Radiopharmaceuticals

Abstract A facile one-pot synthesis of 188Re-complex as a bifunctional chelating agent for the preparation of therapeutic radiopharmaceuticals was accomplished with good labeling yields and radiochemical purity by using a tetrahydroborate exchange resin as a reducing agent for a disulfide ligand as well as the [188Re]perrhenate ion under microwave irradiation.

Removal of dissolved rhenium by sorption onto organic polymers: study of rhenium as an analogue of radioactive technetium

Technetium ( 99Tc) is one of the main components of nuclear wastes. Tc characteristics can be predicted by studying rhenium ( 75Re), one of its chemical analogue, thus avoiding the use of a radioactive element at high concentrations. The objectives of this experimental study was to understand the sorption behavior of Re with natural organic materials in order to define the possible condition of Tc uptake in case where Tc may be transferred into surface or ground waters. As the well-defined organic sorbents we chose chitosan which contains amine –NH 2 groups; poly-galacturonic acid (PGA) and poly-styrene sulfonates (PSS) which contain respectively carboxyl –COOH and sulfonate –SO 3H groups. Concerning the reaction of Re with PGA or with PSS, no interaction between Re and carboxyl or sulfonate groups was found within the detection limit of this study. Re sorption on chitosan was found to be dependent on ionic strength and pH. We propose that non-specific sorption of perrhenate ion ReO 4 – via electrostatic interaction takes place at the protonated amine groups NH 3 +. The polymer-solution interface can be described by the electric diffuse double layer model combined with the Langmuir-Freundlich model. The calculation is in good agreement with our experimental results.

Electrochemical behavior of aqueous acid perrhenate-containing solutions on noble metals: critical review and new experimental evidence

The actual state of the art in the reduction of perrhenate ions on noble metals is reviewed and discussed. Also, with the aim of contributing to better knowledge of this process, results of several experiments are presented. For the first time, spectroscopic evidence on the nature of the deposited rhenium layer on Pt and Rh and the detection of an intermediate in the reduction pathway toward metallic rhenium is provided. The role of the substrate in the electroreduction of perrhenate ions in aqueous acid media is emphasized, because it is directly associated with the formation of different H-containing species as reducing agents. Thus, those metals capable of adsorbing H atoms are able to reduce ReO 4 − to ReO 2 by H ad at potentials more positive than that of the hydrogen evolution reaction. Moreover, H ad reacts with the ReO 2 layer previously deposited, resulting in the formation of Re(III)-soluble species, which subsequently undergo disproportionation to Re and ReO 2. For metals that are not capable of adsorbing H, i.e., Au, molecular hydrogen is the reducing agent, leading to the formation of metallic Re. In addition, ReO 4 − is chemically reduced to metallic Re by hydride.

Synthesis and Characterization of Organic−Inorganic Hybrid Mesoporous Anion-Exchange Resins for Perrhenate (ReO4-) Anion Adsorption

Organic−inorganic hybrid mesoporous anion-exchange resins based on either pure silica or organosilica support materials were prepared and tested for the adsorption of perrhenate (ReO4-) anions in aqueous solutions. The prepared samples were characterized using nitrogen adsorption−desorption measurements, Fourier transform infrared spectroscopy, Raman spectroscopy, small-angle X-ray scattering, 29Si cross-polarization/magic-angle-spinning nuclear magnetic resonance, and scanning transmission electron microscopy. Among the prepared samples, the hybrid mesoporous anion-exchange resins functionalized with N-((trimethoxysilyl)propyl)-N,N,N-tri-n-butylammonium ions showed higher affinities for perrhenate ions than did the resins functionalized with N-((trimethoxysilyl)propyl)-N,N,N-trimethylammonium ions. The enhancement by the bulky ammonium functional ligand is consistent with Hofmeister selectivity.

Radioactively labelled porphyrin derivatives

Radioactive labelling of guanidine-bearing tetraphenylporphyrin and Dy—texaphyrin with selected radionuclides (166Ho and 90Y) is described. A basic characterisation of studied porphyrin and texaphyrin, including their behaviour in a wide range of pH values and data on holmium and yttrium complexation with these compounds was probed using UV-VIS absorption spectrometry. The labelling yield of these macrocyclic molecules depends on the pH of the reaction mixture, metal: ligand ratio and time of incubation. Optimal reaction conditions for formation of porphyrin and texaphyrin radioactive complexes were determined by thin layer chromatography with the detection of β- activity. The ability of porphyrin derivatives to bind anions was examined as well. Our experiments were focused on perrhenate ion (ReO4−) because radiopharmaceuticals labelled with isotopes 186Re and 188Re play an important role in therapy of numerous tumour diseases. The possibility of applying ReO4− anion directly for labelling purposes, without the necessity of its reduction to lower oxidation state, was not proved.

Kinetics of rhenium dioxide deposition on columnar structured platinum electrodes

The kinetics concerning the early stage of the electrodeposition of rhenium dioxide on columnar-structured platinum electrodes from acid aqueous containing perrhenate ions was studied. The results demonstrate a zero-order kinetics obtained by holding the potential at two different values.

Mutual effects of oxo anions in extraction with tetraoctylammonium salts in polar solvents

Mutual effects of perrhenate, permanganate, pertechnetate and perchlorate ions in extraction with quaternary ammonium salts in polar solvents has been studied.

Adsorption–Spectrophotometric Determination of Rhenium from Reflectance Spectra of Its Complexes on a PAN–AV-17 Adsorbent

A simple and sensitive procedure for determining rhenium in 500-mL water samples with a detection limit of 0.2 μg/L was developed. The analysis took 15–20 min. The procedure was based on the dynamic preconcentration of perrhenate ions from neutral or weakly acidic solutions on disks made of a poly(acrylonitrile) (PAN) fiber and filled with an AV-17 ion exchanger (PAN–AV-17 adsorbent). After preconcentration, rhenium was determined at 420 nm from diffuse reflectance spectra of a colored thiocyanate complex that was obtained on treating the disks with a hydrochloric acid solution of potassium thiocyanate and tin(II). The procedure was tested in analyses of lake water and can be used in field conditions.

Crystallization and rhenium MAD phasing of the acyl-homoserinelactone synthase EsaI.

Acyl-homoserine-L-lactones (AHLs) are diffusible chemical signals that are required for virulence of many Gram-negative bacteria. AHLs are produced by AHL synthases from two substrates, S-adenosyl-L-methionine and acyl-acyl carrier protein. The AHL synthase EsaI, which is homologous to the AHL synthases from other pathogenic bacterial species, has been crystallized in the primitive tetragonal space group P4(3), with unit-cell parameters a = b = 66.40, c = 47.33 A. The structure was solved by multiple-wavelength anomalous diffraction with a novel use of the rhenium anomalous signal. The rhenium-containing structure has been refined to a resolution of 2.5 A and the perrhenate ion binding sites and liganding residues have been identified.

Rhenium-Based Hydrosols: Preparation and Properties

Transmission electron microscope (TEM), ultraviolet–visible (UV/vis), electrospray mass spectrometric (ESMS), and X-ray photoelectron spectroscopic (XPS) studies are presented on a little studied rhenium hydrosol system produced by reduction of aqueous K2ReCl6 with hydrazine in the presence or absence of a gum arabic protecting agent. The studies indicate that hydrazine-generated “rhenium hydrosols” are unstable in water and slowly dissolve over time in aqueous media to form the highly stable perrhenate ion.

Ion pairing as a strategy for extraction by modified supercritical carbon dioxide: extraction of radioactive metal ions.

Supercritical fluid carbon dioxide was investigated for its potential to extract perrhenate ion pairs. This has implications for radioactive waste processing because Tc-99, the second row congener of Re, is produced in approximately 6% fission yield from nuclear fuel and pertechnetate is its most common chemical form in aqueous environments. The variables examined to maximize extraction of the perrhenate ion pair were temperature, pressure, solvent modification, and ion-pairing agents. The tetrabutyl-ammonium cation was found to form the most efficient ion pair for extracting perrhenate using methanol-modified (approximately 10%) SFCO2 at 70 degrees C and 477 atm, with 0.083 mg of Re/g of SFCO2 extracted.

Complexes of sodium and caesium perrhenates with calix[4]arene bis(crown-6): a model for pertechnetate ion extraction

The ability of calix[4]arene bis(crown-6) in the 1,3-alternate conformation (BC6) to co-extract caesium and pertechnetate ions from acidic or basic aqueous to organic solutions, which is of interest for nuclear waste reprocessing, has previously been demonstrated. We report the crystal structures of the complexes formed by this ligand with sodium and caesium ions with perrhenate (isoelectronic to pertechnetate) counter-ions, in an acidic medium. The sodium complex [(Na +·H 2O) 2BC6](ReO 4 − ) 2 ( 1) differs from the previously reported sodium nitrate complex mainly by the dissociation of the anion–cation pair. Three forms of the caesium complex are described, [(Cs +) 2(ReO 4 − )BC6](ReO 4 − )·H 2O ( 2), [(Cs +) 2(ReO 4 − )(H 2O)BC6](ReO 4 − )(H 2O) 0.5 ( 3) and [(Cs +) 1.5(ReO 4 − )BC6](ReO 4 − ) 0.5 ( 4), which differ one from the other by the coordination mode of the perrhenate ions (monodentate, bidentate, bridging) and the position of the caesium ion in the crown.

Electrochemical quartz crystal microbalance study of perchlorate and perrhenate anion adsorption on polycrystalline gold electrode

The electrochemical quartz crystal microbalance (EQCM) was used to study adsorption/desorption of perchlorate and perrhenate ions on a bare polycrystalline gold electrode. An electrode mass change in perrhenate solution was about double that of perchlorate. The equivalent mass of adsorbed anions (about 260 and 120 g F −1 respectively) suggests adsorption of perchlorate and perrhenate anions on a polycrystalline gold electrode in the double-layer region. Water molecules are partially expelled from the gold surface during the initial stages of anion adsorption. The water loss is about three times larger for perrhenate compared to perchlorate due to the bigger ionic radius (volume) of the perrhenate anion.

ReO2(dppp)2]Ix[ReO4]1-x.xH2O.CH3OH forx= 0.17 (1), 0.36 (1) and 1 [dppp is 1,3-bis(diphenylphosphino)propane

The crystal structures of [ReO 2 (dppp) 2 ]I x [ReO 4 ] 1-x -xH 2 O.CH 3 OH, where x = 0.17(1), 0.36(1) and 1, i.e. dioxo[propane-1,2-diylbis(diphenylphosphine)-P,P']-rhenium iodide perrhenate hydrate methanol solvate, with iodide partially substituted by the perrhenate ion, are described. The compositions studied correspond to x = 0.17 (1), 0.36 (1) and 1. A solvent water molecule participates in the crystallization in a 1: 1 stoichiometric ratio with the iodide ion. The iodide ion and the water molecule together occupy nearly the same space and volume as the perrhenate ion and this facilitates their substitution. The three compositions studied are isostructural and crystallize in space group P2 1 /n. A contraction of the unit cell is detected as the iodide-ion concentration increases.