Rhenium Sulfide Research Articles

Preparation and Properties of Nanocolloidal Rhenium Sulfide Solution for Lymphoscintigraphic Methods of Micrometastase Examination

A method for the preparation of a nanocolloidal solution of rhenium sulfide is proposed. It includes the following stages: interaction of ammonium perrhenate and sodium thiosulfate in an aqueous solution of gelatin in an acidic medium with heating to 70–80°C; neutralization to pH 7.0; dialysis against saline; desalination and concentrating by ultrafiltration. The resulting colloidal solution contains 85% of particles with an optimal size of 80–100 nm and can be used as a diagnostic tool for lymphoscintigraphy of sentinel lymph nodes in patients with cancer and other diseases.

Preparation and Properties of Nanocolloidal Solution based on Rhenium Sulfide for Lymphoscintigraphy Methods of Micrometastases Investigation

A method for producing a nanocolloidal solution of rhenium sulfide has been suggested. It includes the following stages: interaction of ammonium perrhenate and sodium thiosulfate in aqueous solution of gelatin in an acidic medium by heating up to 70-80°C; pH neutralization up to 7.0; dialysis against saline; desalination and concentrating by ultrafiltration. The obtained colloidal solution contains 85% particles with the optimal size 80-100 nm and can be used as a diagnostic tool in lymphoscintigraphy of “sentinel” lymph nodes in patients with cancer and other diseases.

Layered rhenium sulfide on free-standing three-dimensional electrodes is highly catalytic for the hydrogen evolution reaction: Experimental and theoretical study

Hydrogen evolution reaction is the key for clean energy utilization. Recently, molybdenum disulfide (MoS2) was suggested as a replacement for the most efficient catalyst to date for such reaction, which is platinum. We show here that electrodes based on layered rhenium sulfide (ReS2) catalyst show dramatic improvement when compared to MoS2. We have shown by DFT calculations that ReS2 possesses metallic character of surface states which together with a higher position of Fermi level facilitates electron transfer and pronounced electrochemical activity of this surface. ReS2 has great potential for hydrogen evolution reaction applications.

Catalytic ring-opening addition of thiols to epoxides in the gas-phase over molecular rhenium sulfide cluster complexes [Re6S8X6] (X = Cl, OH, H2O) with retention of their octahedral metal frameworks

A series of molecular rhenium sulfide clusters K4[Re6S8Cl6] (1), K4[Re6S8(OH)6], and [Re6S8(H2O)6]SO4 supported on silica gel catalyze ring-opening addition of thiols to epoxides to yield β-hydroxy sulfides in a stream of hydrogen at temperatures ranging from 175 to 250°C. The thermal activation mechanisms of 1 is studied. Powder X-ray diffraction analyses and Raman spectrometry reveal the retention of integrity of the octahedral cluster framework up to 500°C. Thermogravimetry and elemental analyses of the silica gel-supported 1 show the loss of chlorido ligands, and evolution of hydrogen chloride is observed on activation. No coordinatively unsaturated metal site is observed by CO titration. Titration of the activated cluster shows the appearance of weak Brønsted acid sites with H0≈1.8. The catalytically active site of the silica gel-supported 1 is a hydroxo ligand that is formed by reaction with silanol groups.

Catalytic Activity of Molecular Rhenium Sulfide Clusters [Re6S8(OH)6−n (H2O) n ](4−n)− (n = 0, 2, 4, 6) with Retention of the Octahedral Metal Frameworks: Dehydrogenation and Dehydration of 1,4-Butanediol

A series of molecular rhenium sulfide clusters [Re6S8(OH)6−n (H2O) n ](4−n)− (n = 0, 2, 4, 6) catalyze dehydrogenation of alcohols, and hydrogenation of ketones and olefins in a hydrogen stream at 350 °C. The catalytic activities of the dianionic and neutral clusters (n = 2, 4) are lower than those of tetraanionic and dicationic clusters (n = 0, 6) for all the reactions. When 1,4-butanediol is allowed to react over K4[Re6S8(OH)6], dehydrogenation proceeds to yield 2-hydroxytetrahydrofuran and successively γ-butyrolactone above 300 °C. Over [Re6S8(H2O)6]SO4 dehydration proceeds to yield tetrahydrofuran above 250 °C. The thermal activation mechanisms of these clusters were studied by powder X-ray diffraction analyses, Raman spectrometry, extended X-ray absorption fine structure spectrometry, thermogravimetry, and differential thermal analyses. The catalytically active site of K4[Re6S8(OH)6] is an uncoordinated metal site (Lewis acid site) developed by the loss of a water molecule from two hydroxo ligands. The active site of [Re6S8(H2O)6]SO4 is a Bronsted acid site; the anhydrous aqua cluster dication disproportionates to a hydroxo cluster monocation and a proton. Both of the octahedral cluster frameworks are retained up to 500 °C.

A STUDY OF SELECTED PROPERTIES OF RHENIUM SULPHIDE DISPERSION

Due to potential application of rhenium sulphide in medicine and industry, this study is focused on the properties of synthetic and commercial rhenium sulphide. The main reaction of rhenium sulphide preparation involves potassium perrhenate and sodium thiosulphate in the acidic environment giving a mixture of rhenium sulphide and sulphur. The next step is removing sulphur by its dissolution in ether. Stabilization by Povidone K-25 is needed to obtain rhenium sulphide dispersed with the grain size of 0.5-4 m. The extrapolated value of pHiep for synthesised rhenium sulphide is 2.3 whereas for commercial samples this value is lower than 2. For synthetic sample a dependence of zeta potential on the carrier electrolyte concentration is found. It is larger than that for the commercial sample, probably due to surface oxidation during synthesis or purification.

Étude scintigraphique du drainage lymphatique de la chambre antérieure de l’œil de la souris et ses implications physiopathologiques

For many years, the intraocular lymphatic system and particularly the drainage of the aqueous humor by this system have been considered non-existant. Our study is the first to demonstrate, in a dynamic in vivo fashion, the existence of lymphatic drainage in the mouse eye. This has become possible with lymphoscintigraphy with nano-molecules of rhenium sulphide, marked by technetium-99m and injected into the anterior chamber of the mouse eye. Readings were taken using an experimental gamma camera specially built for the small animal. The hypothesis of a "uveolymphatic" drainage pathway within the ciliary body, contributing to aqueous outflow, has recently been highlighted by new improvements in microbiology (discovery of lymphatic endothelial-specific markers) and imaging. This new pathway may lead to many prospects: the development of techniques for visualization and quantification of this in vivo lymphatic flow may help to increase our understanding of the physiopathology and perhaps treatment of chronic glaucoma as well as neoplastic conditions.

Sentinel Lymph Node Biopsy in Breast Cancer: Review on Various Methodological Approaches

Sentinel lymph node biopsy has been accepted as a standard procedure for early stage breast cancer. In this retrospective analysis, the results obtained with different methodological approaches using radiocolloid with or without blue dye were examined. A total of 158 sentinel lymph node biopsies were performed in 152 patients. Group A (85 patients) underwent lymphatic mapping using a combination of periareolar intradermal radiocolloid and subareolar blue dye injections. Group B (73 patients) underwent only periareolar intradermal radiocolloid injection. One large tin colloid and two small radiocolloids (nanocolloid of serum albumin -NC- and colloidal rhenium sulphide -CS-) were used. Successful lymphatic mapping was attained in 157 of 158 procedures (99.4%). Radiocolloids localized sentinel lymph nodes in 99.4% and blue dye in 75.3% of the cases. The number of sentinel lymph nodes removed was greater in nanocolloid and colloidal rhenium sulphide groups (P ≤0.05). Among 60 metastatic sentinel lymph nodes, frozen section analysis using hematoxylin and eosin staining failed to detect 1 macro- and 10 micrometastasis. Radiocolloid uptake was higher in sentinel lymph nodes accumulating blue dye (1643 ± 3216 counts/10 sec vs 526 ± 1284 counts/10 sec, P <0.001). Higher count rates were obtained by using larger sized colloids (median and interquartile range: tin colloid, 2050 and 4548; nanocolloid, 835 and 1799; colloidal rhenium sulphide, 996 and 2079; P = 0.01). Only 2 extra-axillary sentinel lymph nodes were visualized using periareolar intradermal injection modality. Radiocolloids were more successful than blue dye in sentinel lymph node detection. More sentinel lymph nodes were harvested with small colloids, but different sized radiocolloids were similarly successful. Sentinel lymph nodes having higher radiocolloid uptake tended to accumulate blue dye more frequently. Sentinel lymph nodes manifested higher count rates when a larger colloid was used. Frozen section was very successful in detecting macrometastatic disease in sentinel lymph nodes, but the technique failed in most of the micrometastates.

Use of competitive kinetics for the understanding of deep hydrodesulfurization and sulfide catalysts behavior

Drastic regulations concerning sulfur content in fuels has lead to and still imply numerous researches on hydrotreating reactions and hydrodesulfurization catalysts. The objective of this paper was to illustrate how, besides physicochemical characterization techniques, the kinetics could be also a useful and precious tool for the understanding of the reactions involved and of the catalysts used in this process. That was illustrated by application of competitive kinetics to the comprehension of the transformation of sulfur refractory compounds, of the H2S partial pressure effect on the activity of transition metal sulfides, and to the understanding of support effect for rhenium sulfide based catalysts.

Determination of optimal conditions for pressure oxidative leaching of Sarcheshmeh Molybdenite concentrate using Taguchi method

The present research work is based on finding the optimum conditions for pressure oxidative leaching of the molybdenite concentrate to produce technical-grade molybdic oxide (MoO3) with high recovery through further treatment of the filtrate solution. The Taguchi method was used to design and minimize the number of experiments. By using Taguchi orthogonal (L25) array, five parameters (time, temperature, oxygen pressure, pulp density and acid concentration) at five levels were selected for 25 experiments. The experiments were designed and carried out in a high-pressure reactor in the presence of nitric acid as solvent and oxidizing agent for the molybdenite concentrate and its ReS2 content. The optimum conditions for pressure leaching of molybdenite were obtained through using Signal to Noise analysis and modified by using Minitab software prediction tool. Furthermore, the optimum condition for an economical pressure leaching of rhenium sulfide (ReS2) was achieved with the same process. Analysis of variance (ANOVA) showed that the pulp density is of paramount importance in this process.

The effect of the excisional biopsy in the detection of the sentinel lymph node by lymphoscintigraphy and intraoperative gamma probe in breast cancer.

Objective: Sentinel lymph node (SLN) scintigraphy is used widespread in breast cancer, but the effect of the radionuclide agent, injection technique, the method of biopsy, tumor localization, breast size remain controversial. We examined the effects of the excisional biopsy in the rate of the SLN identification with lymphoscintigraphy (LS) and intraoperative gamma probe (IGP).Material and Methods: One hundred patients (age range: 28-79 yr) with breast cancer were included in the study. They consisted of two groups: Group 1; there were 58 patients without excisional biopsy Group 2; there were 42 patients with excisional biopsy LS: 2 hours before the operation, 37 MBq/ ml Tc 99m colloidal rhenium sulphide was injected at the periaerolar region intradermally Anterior and lateral static images were acquired. IGP: The hot spot of greatest radioactivity were marked on the skin during the surgery with IGP and removed. Excised SLNs were examined with frozen section. After that histopathological and immunohistochemical examinations were performed.Results: SLNs were found in all patients in group 1 (100%), in 39 patients of group 2 (93%) with LS. SLNs were excised in 57 of the 58 patients of group 1 (98%), in 38 of the 42 patients of group 2 (90%) with IGF. Metastases were found in SLNs in 27 patients (28%). Axillary dissection was performed in these patients.Conclusion: According to results of our study the excisional biopsy was not the only factor but also other factors such as breast mass, calcified or metastatic lymph node may be affected the success rate of the SLN. Conflict of interest:None declared.

Chemistry of rhenium sulfide deposition from sulfuric acid solutions

Rhenium sulfi de deposition from sulfuric acid solutions of sodium thiosulfate was examined.

An Optimised Radiolabel Procedure to Prepare 99mTc-Colloidal Rhenium Sulphide to Improve Radiochemical Purity

More than 25% of 99mTc colloidal rhenium sulphide preparations have been reported to have a radiochemical purity of <95% in 11 radiopharmacies. To identify the key parameters involved in radiochemical purity, different preparation procedures were analysed to develop an optimised preparation method. In the first part of this study, various data such as the Nanocis kit batch number, the eluate volume, the time between the two final elutions, the temperature and duration of heating were collected and analysed to determine the critical parameters that significantly decrease radiochemical purity. In the second part, a new procedure was applied and then the same parameters and radiochemical purity values were collected and compared with the results before the new procedure. Among 184 preparations, 137 (75%) had a radiochemical purity exceeding 95%, 25 (13.6%) were between 90 and 95% pure and 22 (12%) were below 90%. Significantly higher radiochemical purity was observed after the implementation of the new preparation procedure (89.5% of 374 preparations had radiochemical purities of > 95%). This new procedure consists in lowering the 99mTc eluate volume and time of heating. The implementation of a new method for the preparation of (99m)Tc colloidal rhenium sulphide based on a comparison of practices in various radiopharmacies resulted in: i) a determination of the critical points of this preparation, ii) an optimised labelling technique to harmonise different practices, and iii) a significant improvement in the preparations radiochemical purity and the quality of the lymphoscintigraphy in the location of sentinel node.

Unexpected Support Effect in Hydrotreating: Evidence of a Metallic Character for ReS2/Al2O3 and ReS2/SiO2 Catalysts

Rhenium sulfide based catalysts were prepared by the incipient wetness impregnation method over alumina and silica supports and evaluated for 4,6-dimethyldibenzothiophene hydrodesulfurization in a high-pressure stirred-tank reactor. The catalyst prepared over silica was about six times more active for hydrodesulfurization than the corresponding catalyst prepared over alumina and a NiMo/Al2O3 industrial reference catalyst. This surprising and positive SiO2 support effect was explained by a metallic character of the supported sulfide, which was demonstrated using a kinetic approach of competitive hydrogenations and by XPS characterization.

Supported rhenium sulfide catalysts in thiophene and 4,6-dimethyldibenzothiophene hydrodesulfurization: Effect of acidity of the support over activities

Three different zeolites, γ-alumina and silica supports were used to prepare ReS 2 catalysts by incipient wetness impregnation of ammonium perrhenate (NH 4ReO 4). The catalysts were characterized and tested in the hydrodesulfurization (HDS) of thiophene in an atmospheric fixed bed reactor, and of the 4,6-dimethyldibenzothiophene (4,6-DMDBT) HDS in a high pressure stirred tank reactor. The results showed that the acidity of the zeolites has a detrimental influence over hydrodesulfurization activity of the Re sulfide, contrarily to the enhancement observed previously with zeolite-supported Mo sulfide catalysts. The catalyst prepared over a non-acidic zeolite (HSZ-390) was found very efficient in thiophene HDS and comparable to silica for 4,6-DMDBT.

Kinetic characterization of unsupported ReS 2 as hydroprocessing catalyst

The hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities of an unsupported rhenium sulfide and a sulfided CoMo/Al 2O 3–SiO 2 catalyst are compared using 4,6-diethyldibenzothiophene (46DEDBT) and 3-ethylcarbazole (3ECBZ) as probe molecules. The active site densities and adsorption-reaction rate constants are determined from transient experiments. It is found that ReS 2 has an unusually high selectivity toward hydrogenation. As such, it has a far higher activity than CoMo/Al 2O 3–SiO 2 for desulfurizing 46DEDBT in the absence of 3ECBZ. The higher activity of ReS 2 arises from a higher turnover frequency as the active site density on ReS 2 is about one-third that on CoMo/Al 2O 3–SiO 2. Due to ReS 2’s higher hydrogenation power, the HDS of 46DEDBT on ReS 2 is less resilient to 3ECBZ inhibition than that on CoMo/Al 2O 3–SiO 2. ReS 2 shows about a sevenfold activity advantage over the CoMo/Al 2O 3–SiO 2 catalyst in the hydrodenitrogenation of 3ECBZ. The results shed some light on the HDS–HDN interactions in real-feed deep HDS.

Catalytic Condensation of Primary Amines, Dehydrogenation of Secondary Amines, and Dealkylation of Tertiary Amines over Solid-State Rhenium Sulfide Clusters with an Octahedral Metal Framework

When solid-state rhenium sulfide clusters with an octahedral metal framework are treated in a hydrogen stream above 300 °C, a catalytic activity for condensation of butylamine to yield N-butylidenebutylamine develops. Primary amines such as ethylamine, pentylamine, and hexylamine are also converted to the corresponding N-alkylidenealkylamines. Secondary amines such as diethylamine, dipropylamine, and dibutylamine are dehydrogenated to the corresponding N-alkylidenealkylamines. When triethylamine is allowed to react, dealkylation proceeds to yield diethylamine and its dehydrogenated product N-ethylideneethylamine. Trimethylamine is also dealkylated to dimethylamine. This series of catalytic behavior is the same as that of palladium and platinum metals. The similarity in selectivity is attributable to the rhenium atom that accepts electrons from the sulfur ligands leading to isoelectronic with the platinum group metals.

Influence of colloid particle profile on sentinel lymph node uptake

Particle size of colloids employed for sentinel lymph node (LN) detection is not well studied. This investigation aimed to correlate particle size and distribution of different products with LN uptake. All agents (colloidal tin, dextran, phytate and colloidal rhenium sulfide) were labeled with (99m)Tc according to manufacturer's instructions. Sizing of particles was carried out on electron micrographs using Image Tool for Windows (Version 2.0). Biodistribution studies in main excretion organs as well as in popliteal LN were performed in male Wistar rats [30 and 90 min post injection (p.i.)]. The injected dose was 0.1 ml (37 MBq) in the footpad of the left posterior limb. Dynamic images (0-15 min p.i.) as well as static ones (30 and 90 min) were acquired in gamma camera. Popliteal LN was clearly reached by all products. Nevertheless, particle size remarkably influenced node uptake. Colloidal rhenium sulfide, with the smallest diameter (5.1 x 10(-3)+/-3.9 x 10(-3) microm), permitted the best result [2.72+/-0.64 percent injected dose (%ID) at 90 min]. Phytate displayed small particles (<15 microm) with favorable uptake (1.02+/-0.14%ID). Dextran (21.4+/-12.8 microm) and colloidal tin (39.0+/-8.3 microm) were less effective (0.55+/-0.14 and 0.06+/-0.03%ID respectively). Particle distribution also tended to influence results. When asymmetric, it was associated with biphasic uptake which increased over time; conversely, symmetric distribution (colloidal tin) was consistent with a constant pattern. The results are suggesting that particle size and symmetry may interfere with LN radiopharmaceutical uptake.

Synthesis of magnetic rhenium sulfide composite nanoparticles

Rhenium sulfide nanoparticles are associated with magnetic iron oxide through coprecipitation of iron salts with tetramethylammonium hydroxide. Sizes of the formed magnetic rhenium sulfide composite particles are in the range 5.5–12.5 nm. X-ray diffraction and energy-dispersive analysis of X-rays spectra demonstrate the coexistence of Fe 3O 4 and ReS 2 in the composite particle, which confirm the formation of the magnetic rhenium sulfide composite nanoparticles. The association of rhenium sulfide with iron oxide not only keeps electronic state and composition of the rhenium sulfide nanoparticles, but also introduces magnetism with the level of 24.1 emu g –1 at 14 kOe. Surface modification with monocarboxyl-terminated poly(ethylene glycol) (MPEG-COOH) has the role of deaggregating the composite nanoparticles to be with average hydrodynamic size of 27.3 nm and improving the dispersion and the stability of the composite nanoparticles in water.

Divergent Electronic Structures of Isoelectronic Metalloclusters: Tungsten(II) Halides and Rhenium(III) Chalcogenide Halides

Same but different: DFT calculations on hexanuclear tungsten(II) halide clusters [W(6)X(8)X'(6)](2-) (X, X'=Cl, Br, I) indicate a breakdown in the isoelectronic analogy between themselves and the isostructural rhenium(III) chalcogenide clusters [Re(6)S(8)X(6)](4-) (see figure).The hexanuclear tungsten(II) halide clusters and the sulfido-halide clusters of rhenium(III) are subsets of a broad system of 24-electron metal-metal bonded assemblies that share a common structure. Tungsten(II) halide clusters and rhenium(III) sulfide clusters luminesce from triplet excited states upon ultraviolet or visible excitation; emission from both cluster series has been extensively characterized elsewhere. Reported here are density-functional theory studies of the nine permutations of [W(6)X(8)X'(6)](2-) (X, X'=Cl, Br, I). Ground-state properties including geometries, harmonic vibrational frequencies, and orbital energy-level diagrams, have been calculated. Comparison is made to the sulfide clusters of rhenium(III), of which [Re(6)S(8)Cl(6)](4-) is representative. [W(6)X(8)X'(6)](2-) and [Re(6)S(8)Cl(6)](4-) possess disparate electronic structures owing to the greater covalency of the metal-sulfur bond and hence of the [Re(6)S(8)](2+) core. Low-lying virtual orbitals are raised in energy in [Re(6)S(8)Cl(6)](4-) with the result that the LUMO+7 (or LUMO+8 in some cases) of tungsten(II) halide clusters is the LUMO of [Re(6)S(8)Cl(6)](4-) species. An inversion of the HOMO and HOMO-1 between the two cluster series also occurs. Time-dependent density-functional calculations using asymptotically correct functionals do not recapture the experimentally observed periodic trend in [W(6)X(14)](2-) luminescence (E(em) increasing in the order [W(6)Cl(14)](2-) < [W(6)Br(14)](2-) < [W(6)I(14)](2-)), predicting instead that emission energies decrease with incorporation of the heavier halides. This circumstance is either a gross failure of the time-dependent formalism of DFT or it indicates extensive multistate emission in [W(6)X(8)X'(6)](2-) clusters. The inapplicability of isoelectronic analogies between clusters of Group 6 and Group 7 is emphasized.