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This dissertation will present three different variations of solvothermal methods for the obtainment of distinct classes of extended materials: the ionothermal synthesis of metal-doped nanoporous aluminophosphates, the hydrothermal synthesis of cationic coordination polymers, and the solvothermal synthesis for the crystallization of racemic polypeptide mixtures.Chapter 1 introduces the field of metal-doped nanoporous aluminophosphates, a class of zeolitic material commonly used as catalysts in the petrochemical industry. The history that led to the development of these materials, their unique chemistry, and their synthetic details are discussed. Ionothermal synthesis is presented as an alternative to the usual hydrothermal method, and its concepts and advantages are detailed. The last section of this chapter is a literature review presenting – to the best of our knowledge – all the current reports of MAPOs synthesized via the ionothermal route. Chapter 2 explores the ionothermal synthesis of AlPO4-5 molecular sieves and the doping of its inorganic framework with Mn2+ or Ni2+. The ionic liquids diisopropylimidazolium bromide (DIPI) and diisobutylimidazolium bromide (DIBU) were used as both the solvents and structure-directing agents, and HF was used as the mineralizer. Varying amounts of water, metal, and HF in the medium led to either AFI, cristobalite, or tridymite framework structures. The product’s phase(s) were determined by powder X-ray diffraction (PXRD). Further structural insights were obtained by studying the coordination of Al3+, P5+, and F- by solid-state nuclear magnetic resonance (SS-NMR) spectroscopy. Electron paragenetic resonance (EPR) spectroscopy and X-ray absorption spectroscopy (XAS) were used to investigate the metal incorporation in the framework. AlPO4-5 and MnAPO-5 phases were isolated. Although there was no evidence of NiAPO-5 formation, the presence of Ni2+ in the reaction medium affected the phase selectivity. Lastly, the thermal stability of the products was determined by thermogravimetric analysis (TGA).Chapter 3 describes the hydrothermal synthesis and single-crystal structure of the novel phase SLUG-53 [Ag(2,4'-bypiridine)NO3]. Close examination of PXRD and single-crystal X-ray diffraction (SCXRD) data reveals the material behaves as a soft-porous crystal, as temperature perturbations led to anisotropic distortions of the unit cell. SLUG-53 undergoes an anion exchange reaction, where the nitrate ions are replaced by perrhenate, a surrogate for the radioactive and hazardous ion pertechnetate. The structure of the resulting material, the novel SLUG-54 ([Ag(2,4'-bypiridine)ReO4]), was also elucidated by SCXRD and revealed that an 8-membered inorganic ring is formed between perrhenate ions and two adjacent chains of polymeric Ag-2,4'-bipyridine. Kinetics studies showed that the exchange reaction follows a pseudo-second-order mechanism. The data was fitted to the Langmuir model to reveal that SLUG-53 shows a superior adsorption capacity of 764 mg ReO4/g SLUG-53. Chapter 4 presents the first high-resolution crystal structure study on the rippled β-sheet formation predicted in 1953 by Pauling and Corey to occur in racemic polypeptide mixtures. While other predictions of these scientists have now become textbook knowledge, such as the pleated β-sheet, the then theorized rippled arrangement was yet to be deeply investigated. The study presented here describes the solvothermal obtainment of [FFF.fff], where L,L,L-tripenhylalanine and D,D,D-triphenylalanine polypeptides strands were found to form dimers in an antiparallel rippled configuration for the first time. Such dimeric units are then further arranged in a herringbone fashion. Ramachandran angles were investigated for [FFF.fff] and three other racemic proteins presenting rippled motifs, which were selected after extensive database mining. Chapter 5 presents a summary and describes future lines of investigation for each of the three projects discussed in this dissertation.

The β- emitter, rhenium-188 (188Re), has long been recognized as an attractive candidate for targeted cancer radionuclide therapy (TRNT). This transition metal shares chemical similarities with its congener element technetium, whose nuclear isomer technetium-99m (99mTc) is the current workhorse of diagnostic nuclear medicine. The differences between these two elements have a significant impact on the radiolabelling methods and should always receive critical attention. This review aims to highlight what needs to be considered to design a successful radiopharmaceutical incorporating 118Re. Some of the most effective strategies for preparing therapeutic radiopharmaceuticals with 188Re are illustrated and rationalized using the concept of the inorganic functional group (core) and a simple ligand field theoretical model combined with a qualitative definition of frontiers orbitals. Of special interest are the Re(V) oxo and Re(V) nitrido functional groups. Suitable ligands for binding to these cores are discussed, successful clinical applications are summarized, and a prediction of viable future applications is presented. Rhenium-188 decays through the emission of a high energy beta particle (2.12 MeV max energy) and a half-life of 16.9 h. An ideal biological target would therefore be a high-capacity target site (transporters, potential gradients, tumour microenvironment) with less emphasis on saturable targets such as overexpressed receptors on smaller metastases. ispartof: MOLECULES vol:28 issue:3 ispartof: location:Switzerland status: published

In this communication experimental and theoretical results are reported affording strong evidence that interactions between electron rich atoms and the metal of tetroxide anions of group 7 elements are a new case of attractive and σ-hole interactions. Single crystal X-ray analyses, molecular electrostatic potentials, quantum theory of atoms-in-molecules, and noncovalent interaction plot analyses show that in crystalline permanganate and perrhenate salts the metal in Mn/ReO4- anion can act as electron acceptors, the oxygen of another Mn/ReO4- anion can act as the donor and supramolecular anionic dimers or polymers are formed. The name matere bond (MaB) is proposed to categorize these noncovalent interactions and to differentiate them from the classical metal-ligand coordination bond.

The thermal analysis behavior of C6H6N3[ReO4] was studied by simultaneous thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) up to 700 °C under argon. Such analysis afforded rhenium metal, which was characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. XRD peak broadening due to crystallite size and lattice strain was analyzed by both Williamson-Hall (W-H) and Debye-Scherrer (D-S) methods. Efforts to isolate Re metal from the thermal treatment of benzotriazole (BTA = C6H5N3) with NH4ReO4 and Re2O7 under various atmospheres and temperatures are also reported. The results provide a significant insight into the chemistry of group VII transition metals, investigate the potential use of benzotriazole as a reducing agent for metal productions, and demonstrate a successful convenient method for rhenium metal production, which could be applied to other refractory metals.

In this work, an ion imprinted polymer (ReO4–-IIP) of the perrhenate ion based on acrylamide (AM) and acrylic acid (AA) was prepared by solution polymerization using ReO4– as a template ion, N,N-me...

Computationally designed ion imprinted polymers (IIP) were synthesised for selective binding of perrhenate ion from CMSX-4 superalloy leach solutions. A library of functional monomers was screened using Density Functional Theory (DFT) based on their binding energy with perrhenate ion. DFT calculations were also employed to determine the template:monomer ratio of 1:2 from binding energy calculation of the complex formed, and perrhenate ion formed the most stable complex with protonated 4-vinylpyridine (4VP) at 1:2 molecular ratio. An optimum imprinting ratio of 2:4:40 for the functional monomer:cross-linker:perrhenate ion template was calculated using molecular dynamics simulation of a fixed number of component molecules in a periodic boundary and isothermal conditions (NVT-Molecular Dynamics) using MM+ force field. The perrhenate ion selective IIPs were synthesised via bulk polymerisation and combinatorial screening of the imprinting porogen composition was employed to compliment the computational screening. The resulted IIPs showed fast kinetics, high binding capacity (122 mg Re/g polymer), and adsorption processes governed by pseudo-second order kinetics. The IIP synthesised using 4-vinylpyridine and ethylene glycol dimethylacrylate (EGDMA) show superior selectivity towards perrhenate ion in the presence of the oxides, hydroxides, and chlorides of Al, Co, Cr, Hf, Mo, Ni, Ta, Ti, and W in the feed leach solution at pH = 7.0. The perrhenate ion IIPs demonstrated excellent chemical and physical stability towards extreme acidic stripping conditions, and storage for an extended period. Therefore, the use of perrhenate ion imprinted polymers for separation as part of the industrial recycling of rhenium from superalloy leach solutions is recommended.

The theoretical description of a new sandwich-like rhenium-based polymer composite cathodic electrodeposition has been given. The cathodic process is realized by perrhenate-ion electrochemical reduction to rhenium (IV) oxide, acting as an in situ formed oxidant for 3,4-dimethoxypyrrole polymerization. It is shown that the polymer deposition in this system is realized by more efficient manner than during the direct electropolymerization. The polymer composite has to have a well-developed morphology and enhanced conductivity by sandwich-like structure. The oscillatory behavior, in this case, is also possible, being caused by the DEL influences on both electrochemical and chemical stages of the process. DOI: http://dx.doi.org/10.17807/orbital.v12i2.1193

The strength of hydrogen bonding to and structure of hydrated oxometallate ions in aqueous solution have been studied by double difference infrared (DDIR) spectroscopy and large-angle X-ray scattering (LAXS), respectively. Anions are hydrated by accepting hydrogen bonds from the hydrating water molecules. The oxygen atom of the permanganate and perrhenate ions form weaker and longer hydrogen bonds to water than the hydrogen bonds in bulk water (i.e., they act as structure breakers), while the oxygen atoms of the chromate, dichromate, molybdate, tungstate, and hydrogenvanadate ions form hydrogen bonds stronger than those in bulk water (i.e., they act as structure makers). The oxometallate ions form one hydration shell distinguishable from bulk water as determined by DDIR spectroscopy and LAXS. The hydration of oxoanions results in X–O bond distances ca. 0.02 Å longer than those in unsolvated ions in the solid state not involved in strong bonding to counterions. The oxygens of oxoanions with a central atom from the second and third series in the periodic table and the hydrogenvanadate ion hydrogen bind three hydrating water molecules, while oxygens of oxoanions with a heavier central atom only form hydrogen bonds to two water molecules., The strength of the hydrogen bonding to and the structure of hydrated oxometallate ions in aqueous solution have been studied by double difference infrared spectroscopy and large-angle X-ray scattering, respectively.

In this article, nano-sized calcium perrhenate was prepared using the microemulsion reaction method. By the aid of surfactant, the calcium perrhenate was suspended in pentaerythritol ester base oil to serve as a lubricating additive. The tribological performances of the oil containing calcium perrhenate at elevated temperatures were investigated by four-ball tests and ball-on-disk reciprocating sliding tests. The underlying lubricating mechanism of the calcium perrhenate additive was explored using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry/thermogravimetry, Raman spectroscopy, and X-ray photoelectron spectroscopy. The four-ball test results indicated that the oil containing calcium perrhenate featured lower friction coefficients, smaller wear scar diameters, and lower temperature rising performance than the base oil under an applied load of 392 N. The optimum lubricating property was obtained when the additive was at a concentration of 0.05 wt%. The tribological performance in a wide temperature range results showed that the friction coefficients of the oil containing calcium perrhenate were slightly lower than those of the base oil at a relatively low temperature range, and decreased as the temperature increased within a high range. The improved tribological performances owed to the formation of a protective layer, which consisted of the shear-susceptible calcium perrhenate additive as well as some native metal oxides that enhanced the layer carrying capacity during rubbing after chemical degradation of base oil. This protective layer acted as a barrier between the rubbing surfaces, preventing them from directly contacting each other at elevated temperatures.

Abstract Carbon aerogels are unique type of amorphous carbon-based materials with an extraordinary properties including light weight, well-developed and tailored pore structure, high specific surface area, low electrical resistivity and high purity. Therefore carbon aerogels can be used in numerous applications, including energy storage materials such as supercapacitors or lithium-ion batteries. Synthesis of hydrogel requires accurate concentration of monomers and catalysts, exact temperature and time. Low-density carbon aerogel can be produced using a complicated supercritical drying method, which allows to expel solvent without carbon porous structure collapse. Here we report a possibility to use novel type of resorcinol/formaldehyde gelation catalyst based on rhenium salt. The organic gel obtained using lithium perrhenate was traditionally carbonized and examined with respect to energy storage properties. It was found that interaction of lithium and rhenium atoms with monomers resulted in completely different structure than using typical sodium carbonate catalyst. Graphic abstract

Highly selective anion recognition and extraction are critical and challenging to deep removal of pollutants from the environment and effective recovery of valuable chemicals from low–content (at sub–ppm or ppb level) sources. Herein, we detail the gram–scale synthesis of a superphane 2, a new supramolecular host that was found capable of encapsulating ReO4– with high selectivity, as suggested by the single–crystal structures, NMR spectroscopy and theoretical calculations. Under solid–liquid extraction condidtions, 2 proved able to extract perrhenate from the solid mixture containing trace ReO4– (as low as 200 ppb) with near 100% selectivity over other 7 competing anions. Under liquid–liquid extraction conditions, using 2 as the supramolecular extractant, over 99.99% of ReO4– could be separated from the complex simulated aqueous waste streams containing ppm–level perrhenate and large excess of competing ions. Notably, after extraction, 2 could be recycled and reused by simple treatment with NaHCO3. This study opens up the door to development of superphane–based advanced materials for deep elimination of pollutants from the envirenment and purification of chemicals of interest with high efficiency and selectivity.

Liquid-liquid extraction for the removal of pertechnetate (99TcO4-) and perrhenate (ReO4-) is reported based on using the tripodal extractant N,N,N',N',N″,N″-hexa-n-octylnitrilotriacetamide (HONTA) composed of three amide groups and a tertiary amine. The extraction behaviors were compared with those using alkyldiamideamines (ADAAM(Oct) and ADAAM(EH)), and the commercial amine-type extractant, trioctylamine (TOA). HONTA quantitatively extracted 99TcO4- and ReO4- in the pH range from 1.0 to 2.5 by the co-extraction of protons. The extraction performance of the extractants was improved in the order of HONTA > ADAAM(Oct) > ADAAM(EH) > TOA. 99TcO4- and ReO4- in the extracting phase were successfully stripped using neutral aqueous solutions as the receiving phase, and the extraction ability of HONTA was maintained after five repeated uses.

We report the structural, spectroscopic, and computational studies of two new Re(I) tricarbonyl complexes bearing 2,3,6,7-tetraphenyl-1,4,5,8-tetraazaphenanthrene (Ph4TAP) and 4,5-diazafluoren-9-one (dafone) having a coordinated perrhenate group obtained via in situ superoxidation of Re(I) to Re(VII); intramolecular and intermolecular n → π* interactions are dominant and stabilize the molecular geometry and crystal packing.

The anions pertechnetate, TcO4-, and perrhenate, ReO4-, exhibit very similar chemical and physical properties. Revealing and understanding disparities between them enhances fundamental understanding of both. Electrospray ionization generated the gas-phase proton bound dimer (TcO4-)(H+)(ReO4-). Collision induced dissociation of the dimer yielded predominantly HTcO4 and ReO4-, which according to Cooks' kinetic method indicates that the proton affinity (PA) of TcO4- is greater than that of ReO4-. Density functional theory computations agree with the experimental observation, providing PA[TcO4-] = 300.1 kcal mol-1 and PA[ReO4-] = 297.2 kcal mol-1. Attempts to rationalize these relative PAs based on elementary molecular parameters such as atomic charges indicate that the entirety of bond formation and concomitant bond disruption needs to be considered to understand the energies associated with such protonation processes. Although in both the gas and solution phases, TcO4- is a stronger base than ReO4-, it is noted that the significance of even such qualitative accordance is tempered by the very different natures of the underlying phenomena.

A polyligand citrate-pyrophosphate electrolyte is proposed, which makes it possible to obtain uniform bright coatings containing 15–40 at.% Re and 10–4 at.% W and a current efficiency of up to 93% depending on the concentration of potassium perrhenate in the solution. The dependence of the chemical composition, current efficiency and morphology of ternary electrolytic alloys CoWRe on the electrolyte components and the electrolysis conditions is presented. The coatings obtained are fine-crystalline and X-ray amorphous and have a high microhardness of 574–788 HV.

The title hydrated salt, tris­[hexa­amminecobalt(III)] tetroxidorhenate(VII) tetra­kis­[hexa­fluorido­rhenate(IV)] hexa­hydrate, arose unexpectedly due to possible contamination of the K2ReF6 starting material with KReO4. It consists of octa­hedral [Co(NH3)6]3+ cation (Co1 site symmetry 1), tetra­hedral [ReVIIO4]− anions (Re1 site symmetry 1) and octa­hedral [ReIVF6]2− anions (Re site symmetries, Re2: 1; Re3 and Re4: ). A network of N—H⋯F hydrogen bonds consolidates the structure., The title hydrated salt, tris­[hexa­amminecobalt(III)] tetraoxidorhenate(VII) tetra­kis­[hexa­fluorido­rhenate(IV)] hexa­hydrate, arose unexpectedly due to possible contamination of the K2ReF6 starting material with KReO4. It consists of octa­hedral [Co(NH3)6]3+ cation (Co1 site symmetry 1), tetra­hedral [ReVIIO4]− anions (Re site symmetry 1) and octa­hedral [ReIVF6]2− anions (Re site symmetries 1and ). The [ReF6]2− octa­hedral anions (mean Re—F = 1.834 Å), [Co(NH3)6]3+ octa­hedral cations (mean Co—N = 1.962 Å), and the [ReO4]− tetra­hedral anion (mean Re—O = 1.719 Å) are slightly distorted. A network of N—H⋯F hydrogen bonds consolidates the structure. The crystal studied was refined as a two-component twin.

Technetium-99 (99Tc) is a major contaminant at nuclear power plants and several US Department of Energy sites. Its most common aqueous species, pertechnetate (TcO4-), is very mobile in the environment, and currently there are no effective technologies for its sequestration. In this work, a porous iron (pFe) material was investigated for TcO4- and perrhenate (ReO4-) sequestration from artificial groundwater. The pFe was significantly more effective than granular iron for both TcO4- and ReO4- sequestration under oxic conditions. The Tc removal capacity was 27.5 mg Tc/g pFe at pH ˜6.8, while the Re removal capacity was 23.9 mg Re/g pFe at pH ˜10.6. Tc K-edge XANES and EXAFS analyses indicated that the removed Tc species was 70-80% Tc(IV) that was likely incorporated into Fe corrosion products (i.e., Fe(OOH), Fe3O4) and 20-30% unreduced TcO4-. In contrast, the removed Re species was ReO4- only, without detectable Re(IV). In addition, the sequestered ReO4- was not extracted (

The standard (p° = 0.1 MPa) molar enthalpies of sublimation, at 298.15 K, of methyltrioxorhenium(VII), Δ sub H m o [CH3ReO3] = 70.2 ± 0.4 kJ mol−1, and dirhenium decacarbonyl, Δ sub H m o [Re2(CO)10] = 97.4 ± 0.9 kJ mol−1, corresponding to well characterized crystalline phases, were determined by Calvet microcalorimetry. These results, along with structural information obtained in this work by single crystal X-ray diffraction for CH3ReO3, or previously reported for Re2(CO)10, tetramethylammonium perrhenate(VII), [N1111][ReO4], and hexamethylrhenium(VI), Re(CH3)6, were used to extend our previously developed all-atom force field for organometallic compounds, to rhenium species. The new parametrization was able to reproduce the enthalpies of sublimation and unit cell parameters of the test set with maximum absolute deviations of 3.3 kJ⋅mol−1 and

Oxorhenium catalysts effectively transform biomass-derived polyols into corresponding alkenes via deoxydehydration (DODH) with a secondary alcohol as a hydrogen donor. This study describes the preparation of unsupported rhenium oxide nanoparticles (ReOx NPs), their use as DODH heterogeneous catalyst, and changes in the speciation and structure of Re during catalysis leading to a possible mechanism for DODH by a heterogeneous catalyst. The unsupported nanoparticles catalyze various polyols transformation to produce alkenes with high efficiency and recyclability. X-ray spectroscopy analysis shows that the structure of as-prepared ReOx NPs is similar to perrhenate with oxidation state between Re(VI) and Re(VII). Under reaction conditions and postcatalysis, the ReOx NPs are reduced by approximately two oxidation units. Kinetic isotope effect demonstrates that dissociation of a C–H bond during reduction of ReOx NPs by 3-octanol is part of the rate-determining step. Based on all experimental observations, the m...

Актуальность. Рений и его сплавы являются тугоплавкими, жаропрочными, жаростойкими и коррозионностойкими материалами, которые используются в авиа- и ракетостроении, электротехнике, при производстве катализаторов. Рений относится к редким и рассеянным элементам, что обусловливает необходимость совершенствования технологических процессов по его извлечению из природного сырья и отработанных материалов, а также повышения точности аналитических методик его определения. Электрохимические методы являются оптимальными с точки зрения затратности, экспрессности и доступности для анализа и переработки ренийсодержащего сырья. В связи с этим изучение закономерностей протекания электродных процессов с участием рения и его соединений является актуальным. Цель: установить последовательность протекания катодного восстановления перренат-ионов в щелочных электролитах. Объекты: растворы перрената аммония, растворы гидроксида натрия. Методы: постоянно- и переменнотоковая полярография, циклическая вольтамперометрия, накопительный потенциостатический электролиз. Результаты. Определён интервал потенциалов катодного восстановления ионов ReO4- (1*10-5…1*10-2 М) в щелочной среде (1…10 М NaOH) на ртутных электродах, составляющий -1,25…-1,75 В (нас. х.с.э.). По результатам определения температурной зависимости величины предельного тока восстановления и зависимости тока от высоты столба капающего электрода установлен существенный вклад каталитической и адсорбционной составляющих в суммарное значение катодного тока. С использованием циклической вольтамперометрии установлена последовательность и предложена схема восстановления ReO4- в щелочных электролитах, включающая электродные, химические и адсорбционные стадии. При интерпретации результатов использованы данные по потенциостатическому электролизу и вольтамперометрии химически синтезированного оксида ReO2. Показана важность учёта полученных результатов при определении рения с использованием электрохимических методов анализа. Relevance. Rhenium and its alloys are refractory, heat-resistant, high-temperature, and corrosion-resistant materials which are used in aircraft and rocket engineering, electrical engineering, in production of catalysts. Rhenium belongs to rare elements, this necessitates the improvement of technological processes for its extraction from natural raw materials and waste materials, as well as improving the accuracy of analytical methods for its determination. Electrochemical methods are optimal in terms of cost, expressiveness and availability for analysis and processing of rhenium-containing raw materials. In this regard, the study of the regularities of the electrode processes involving rhenium and its compounds is relevant. The aim of the research is to establish the sequence of cathodic reduction of perrhenate ions in alkaline electrolytes. Objects: ammonium perrhenate solutions, sodium hydroxide solutions. Methods: direct and alternating current polarography, cyclic voltammetry, accumulative potentiostatic electrolysis. Results. The authors have determined the interval of potentials of cathodic reduction of ReO4 - ions (1*10-5…1*10-2М) in alkaline medium (1...10 M NaOH) at mercury electrodes is -1,25…-1,75 V (sat. Ag/AgCl/KCl). A significant contribution of catalytic and adsorption current components to the total value of cathodic current was established on the basis of temperature dependence of limiting current and current dependence on height of dropping Hg-electrode column. A sequence for reduction of ReO4 - in alkaline electrolytes was established using cyclic voltammetry, and a scheme of the cathodic process was proposed which includes electrode, chemical and adsorption stages. Experimental data on potentiostatic electrolysis and on voltammetry of chemically synthesized ReO2 were used to interpret the polarographic results. The paper demonstrates the importance of the obtained results for analytical determination of rhenium.

Environmental contamination by 99Tc(VII) from radioactive wastewater streams is of particular concern due to the long half-life of 99Tc and high mobility of pertechnetate. Herein, we report a novel MXene-polyelectrolyte nanocomposite with three-dimensional networks for enhanced removal of perrhenate, which is pertechnetate simulant. The introduction of poly(diallyldimethylammonium chloride) (PDDA) regulates the surface charge and improves the stability of Ti2CT x nanosheet, resulting in Re(VII) removal capacity of up to 363 mg g-1, and fast sorption kinetics. The Ti2CT x/PDDA nanocomposite furthermore exhibits good selectivity for ReO4- when competing anions (such as Cl- and SO42-) coexist at a concentration of 1800 times. The immobilization mechanism was confirmed as a sorption-reduction process by batch sorption experiments and X-ray photoelectron spectroscopy. The pH-dependent reducing activity of Ti2CT x/PDDA nanocomposite toward Re(VII) was clarified by X-ray absorption spectroscopy. As the pH increases, the local environment gradually changes from octahedral-coordinated Re(IV) to tetrahedral-coordinated Re(VII). The overall results suggest that Ti2CT x/PDDA nanocomposite may be a promising candidate for efficient elimination of Tc contamination. The reported surface modification strategy might result in applications of MXene-based materials in environmental remediation of other oxidized anion pollutants.

The methods of stationary voltammetry and chronovoltammetry have been used to study deposition processes of ternary CoWRe alloys at different rhenium content of the electrolyte and deposition current density. It has been found that the limiting currents have a diffusive nature and are proportional to the concentration of perrhenate ions in the electrolyte. The CoWRe alloys should be formed by the discharge of bimetallic citrate complexes of the following composition [(Co)(WO4)(H)(Cit)]2- and rhenium electrodeposition. Rhenium does not form complexes with citrate ions and deposits better in an alloy with iron group metals than in the form of an individual metal from a perrhenate solution. It can be assumed that the discharge of rhenium into the alloy occurs from a surface complex, the nature of which has not yet been established. The alloy current efficiency reaches 93% due to the high overpotential of hydrogen evolution on the alloy surface. According to the results of investigations of the catalytic properties of alloys in the hydrogen reduction reaction, it has been found that with increasing the rhenium content of the electrolyte and alloy, an increase in hydrogen overpotential is observed. Based on the Tafel coefficients found, it was found that in an acidic and neutral medium, the limiting stage of the cathodic and anodic reaction is the transfer of the first electron. In an alkaline medium, the anode process is complicated by the simultaneous transport of two electrons. The found values of corrosion resistance are 1-2 kOm·cm-2 in solutions of 0.01 M H2SO4; 20-110 kOm·cm-2 in 2.5% NaCl; 10-30 kOm·cm-2 in 1.0 M KOH. Based on the dependence of corrosion resistance on the refractory metals content of the alloy and the electrodeposition conditions, the optimum deposition current density of 10 mA·cm-2 has been found.

A family of pyridyl-functionalized arylacetylene C–H hydrogen bonding (HB) receptors were synthesized and binding interactions to perrhenate (ReO4–) studied in the solid state. The protonation and alkylation state of the pyridine nitrogen dictate the location and denticity of the interactions. X-ray structures of neutral 1 and singly charged 2a+·ReO4– reveal the formation of favorable self-complementary dimers, owing to the presence of nitrogen HB acceptor sites. Dismissal of these dimers upon elimination of nitrogen HB acceptors on the receptor result in an array of multidentate C–H HB receptor–guest contacts.