Osmium Oxide Research Articles

AACVD synthesized tungsten oxide-NWs loaded with osmium oxide as a gas sensor array: enhancing detection with PCA and ANNs.

This paper presents the fabrication of sensors based on tungsten trioxide nanowires decorated with osmium oxide nanoparticles using the aerosol-assisted chemical vapor deposition (AACVD) technique. This methodology allows the obtention of different osmium oxide decoration loadings on the tungsten oxide nanowires. The morphological and chemical characteristics; and the structural properties of the sensing layers of the sensors were studied using different techniques such as FESEM, HR-TEM, and ToF-SIMS. The gas sensing properties were analyzed for pure tungsten trioxide sensors and tungsten trioxide loaded with osmium exposed to nitrogen dioxide, hydrogen, and ethanol, thus assessing the impact of the loading on the sensor response. A sensor array comprising pure and osmium-loaded tungsten oxide devices coupled to multivariate pattern recognition techniques is shown to perform well in gas identification and quantification tasks, offering promising implications in the field of gas sensing technology.

Origin of Magnetism in a Supposedly Nonmagnetic Osmium Oxide.

A supposedly nonmagnetic 5d^{1} double perovskite oxide is investigated by a combination of spectroscopic and theoretical methods, namely, resonant inelastic x-ray scattering, x-ray absorption spectroscopy, magnetic circular dichroism, and multiplet ligand-field calculations. We found that the large spin-orbit coupling admixes the 5d t_{2g} and e_{g} orbitals, covalency raises the 5d population well above the nominal value, and the local symmetry is lower than O_{h}. The obtained electronic interactions account for the finite magnetic moment of Os in this compound and, in general, of 5d^{1} ions. Our results provide direct evidence of elusive Jahn-Teller distortions, hinting at a strong electron-lattice coupling.

Synthesis of biogenic cerium oxide-supported osmium oxide nanoalloy from Oldenlandia umbellata L. plant extract for pharmacological applications

Synthesis of biogenic cerium oxide-supported osmium oxide nanoalloy from Oldenlandia umbellata L. plant extract for pharmacological applications

Citrate-functionalized osmium nanoparticles with peroxidase-like specific activity for highly efficient degradation of phenolic pollutants

Platinum group metals-based nanomaterials have shown promise as enzyme mimics, and attracted much attention in the fields of chemical catalysis, biosensor, therapy and pollutants degradation. Surprisingly, only a few works exist on the exploration of osmium-based nanozymes, and the catalytic activities and applicable potentials thereof have not been comprehensively understood. Herein, we prepared a kind of citrate-functionalized osmium nanoparticles (Os-citrate NPs) by one-pot synthesis strategy. The obtained Os-citrate NPs can boost hydrogen peroxide (H2O2) to produce hydroxyl radical (•OH), enabling it to serve as a peroxidase mimic. Steady-state kinetics revealed that Os-citrate NPs is rather potent and peroxidase-like specific nanozyme. Doping a certain amount of osmium oxides (OsO2) in the surface of Os-citrate NPs can greatly improve the production of •OH from H2O2, enhancing the peroxidase-like specific activity. We applied this Os-citrate catalyst in advanced oxidative degradation of phenolic pollutants. In a wide pH range of 2.0–10, 4-nitrophenol could be fast degraded by the combination of H2O2 with Os-citrate NPs. As a proof-of-concept, the Os-citrate nanozyme was successfully employed in highly efficient degradation of phenolic pollutants. To the best of our knowledge, this is the first report on the application of Os-based peroxidase-like nanozymes in highly efficient degradation of organic pollutants.

The Myth of Median Nerve in Forearm and Its Role in Double Crush Syndrome: A Cadaveric Study.

Purpose: This study aims to histologically compare the median nerve in the arm, forearm, and wrist, to help understand how cervical radiculopathy in a double crush phenomenon causes distal nerve dysfunction at the carpal tunnel and median nerve with concurrent absence of symptoms at the forearm.Methods: The study was performed on 12 fresh cadaveric upper limbs free from any injury or operation. Male cadavers in the age range of 35–40 years were used. The dissection of the median nerve and the histological examination of the specimens from the arm, forearm, and wrist were conducted to evaluate variations in the epineurium thickness (μm), perineurium thickness (μm), number of fascicles per nerve trunk, area percent of myelin covering, and area percent of neurolemmal sheath.Results: Morphometric and statistical results of the cadaveric median nerve trunk revealed that the mean epineurium and perineurium thickness measured in H&E-stained sections in the forearm were significantly greater than those in the arm and wrist specimens. Further, the mean percent area of the myelin covering in the forearm was significantly lower than that in the arm and wrist specimens in the sections stained with osmium oxide (p < 0.001). There were, however, no significant differences in the neurolemmal sheath among the arm, forearm, and wrist specimens in the silver-stained sections.Conclusion: The histological differences explained the high concomitant occurrence of carpal tunnel syndrome (CTS) and cervical radiculopathy and the concurrent absence of symptoms at the forearm. Hence, we suggest cautious evaluation of patients with upper limb symptoms, since the management of these conditions requires a different approach.

Thermogravimetric Study of Oxidation Firing of Rhenium- and Osmium-Containing Lead Sludge

Results are provided for thermal and thermogravimetric studies of lead sludge in the presence of and without oxidizing agents in order to determine the thermally active part of the charge composition. It is shown that during oxidation firing of lead sludge the process begins with charge dewatering and organic compound decomposition, and rare metal oxidation commences after complete destruction of organic compounds. Addition of sodium nitrate or calcium hypochlorite oxidizing agents provides complete oxidation of rhenium and osmium in the range of 400–650°C with the subsequent extraction of osmium into sublimate and concentration of rhenium in the form of perrhenate compounds in the ash. In this case decomposition of organic substances proceeds in parallel with oxidation reactions of rare metals without affecting their oxidation.

Advantages and limitations of catalytic oxidation with hydrogen peroxide: from bulk chemicals to lab scale process

ABSTRACT 21st century global market place is moving towards subtainable development and without this approach our future would be at risk. Today’s chemical industries need to give more focus for the planet through improving the environmental footprints of fuels and chemicals manufacturing processes. Oxidation and hydrogenation processes are widely used in the production of chemicals and fuels. Oxidation processes are especially important to convert petroleum-based materials to useful petrochemicals of higher oxidation state. Many existing oxidation processes, however, still rely on the use of stoichiometric oxidants, such as dichromate/sulfuric acid, permanganates, periodates, chromium oxides, osmium oxide etc., and remain a major source of environmental pollution. Therefore, oxidation processes using eco-friendly oxidizing agents such as molecular oxygen, ozone and hydrogen peroxide (H2O2) are incresingly becoming important to improve the environmental sustainability. Hydrogen peroxide is especially attractive for the liquid-phase oxidation due to the presence of high percentage of active oxygen and the production of water as only by-product. As a result, H2O2-based eco-friendly oxidation processes are gradually replacing some well-established processes such as production of propylene oxide, caprolactam, phenol etc. Moreover, recent advances in the area of oxidation catalysis is promoting H2O2-based technologies to emerge as a frontline, eco-friendly sustainable processes. H2O2 is also finding greater applications in pulp/paper industries and waste water treatment as a substitute of chlorine-based oxidizing agents. Herein, we have analyzed various reactions using H2O2 as an oxidant and their recent advancement to bring important aspects of H2O2-based oxidation processes and catalysis. Moreover, various aspects of using H2O2 toward development of sustainable oxidation processes have been analyzed with respect to factors affecting the end uses in chemical industry such as efficiency, catalyst and reaction pathways. We have reviewed manufacturing trends of H2O2 and emerging applications of H2O2 in sustainable oxidation processes. Critical discussions have also been made on the opportunities and challenges with emerging H2O2 based oxidation processes in the production of bulk as well as specialty chemicals.

High-pressure synthesis, crystal structure, and magnetic properties of hexagonal Ba3CuOs2O9

A new polymorph of the triple perovskite Ba3CuOs2O9, which usually exists in the orthorhombic phase, was synthesized under high-pressure and high-temperature conditions at 6 GPa and 1100 °C. Under the synthetic condition, Ba3CuOs2O9 crystallizes into a hexagonal structure (P63/mmc) with a = 5.75178(1) Å and c = 14.1832(1) Å, and undergoes a 1.36% increment in density, compared to that of the orthorhombic phase. Although Ba3CuOs2O9 maintains its 6 H perovskite-type structure, the distribution of Cu and Os atoms are dramatically altered; (Cu)4a(Os,Os)8f transits to (Os)2a(Cu,Os)4f ordering over the corner- and face-sharing sites, respectively. The hexagonal Ba3CuOs2O9 exhibits a ferrimagnetic transition at 290 K, which is in stark contrast to the antiferromagnetic transition at 47 K exhibited by the orthorhombic Ba3CuOs2O9. The enhanced transition temperature is most likely due to the strongly antiferromagnetic Os5+–O–Os5+ bonds and the moderately antiferromagnetic Os5+–O–Cu2+ bonds, the angles of which are both approximately 180°. The 290 K ferrimagnetic transition temperature is the highest reported for triple-perovskite osmium oxides. Besides, the coercive field is greater than 70 kOe at 5 K, which is remarkable among the coercive fields of magnetic oxides.

Computational study on epoxidation of propylene by dioxygen using the silanol-functionalized polyoxometalate-supported osmium oxide catalyst

The silanol-functionalized POM-supported single-site Os oxide catalyst has been theoretically considered for epoxidation of propylene in the presence of dioxygen based on density functional theory calculations.

Possible Origin of the Absence of Magnetic Order in LiOsO3: Spin–Orbit Coupling Controlled Ground State

LiOsO3 is the first experimentally confirmed polar metal with ferroelectric‐like distortion. One puzzling experimental fact is its paramagnetic state down to very low temperature with negligible magnetic moment, which is anomalous considering its 5d3 electron configuration since other osmium oxides (e.g., NaOsO3) with 5d3 Os ions are magnetic. Here the magnetic and electronic properties of LiOsO3 are re‐investigated carefully using the first‐principles density functional theory. The calculations reveal that the magnetic state of LiOsO3 can be completely suppressed by the spin–orbit coupling. The subtle balance between significant spin–orbit coupling and weak Hubbard U of 5d electrons can explain both the nonmagnetic LiOsO3 and magnetic NaOsO3. This work provides a reasonable understanding of the long‐standing puzzle of magnetism in some osmium oxides.

OsF6 ]x- : Molecular Models for Spin-Orbit Entangled Phenomena.

Heavy 5d elements, like osmium, feature strong spin-orbit interactions which are at the origin of exotic physical behaviors. Revealing the full potential of, for example, novel osmium oxide materials ("osmates") is however contingent upon a detailed understanding of the local single-ion properties. Herein, two molecular osmate analogues, [OsF6 ]2- and [OsF6 ]- , are reported as model systems for Os4+ and Os5+ centers found in oxides. Using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) techniques, combined with state-of-the-art ab initio calculations, their ground state was elucidated; mirroring the osmium electronic structure in osmates. The realization of such molecular model systems provides a unique chemical playground to engineer materials exhibiting spin-orbit entangled phenomena.

Synthesis of osmium borides by mechanochemical method

AbstractTransition metal osmium borides were synthesized by mechanochemical method using high‐energy ball‐milling with Os (Osmium) and B (Boron) powders as raw materials. The formation process, reaction mechanism, and thermal stability of the mechochemically synthesized osmium borides were studied. Almost pure Os2B3 phase was obtained when the Os‐to‐B molar ratio was 1:2; while ReB2‐type hexagonal OsB2 with a small amount of RuB2‐type orthorhombic OsB2 was obtained when the Os‐to‐B molar ratio was 1:3. Stoichiometry OsB2 was obtained from boron rich starting mixture powders due to the B loss during the high‐energy ball‐milling process. It was also found that WC and osmium oxide were present as contaminants after ball milling for 40 hours. Heat treatment results revealed that the as‐synthesized Os2B3 powders are thermally stable in flowing Ar up to 800°C, but a transformation from hexagonal to orthorhombic structure partially occurred for the OsB2 powders as low as 600°C.

Single‐Site Osmium Catalysts on MgO: Reactivity and Catalysis of CO Oxidation

MgO-supported osmium dioxo species, described as Os(=O)2 {-Osupport }1 or 2 (the brackets denote O atoms of the MgO surface), formed from Os3 (CO)12 via supported Os(CO)2 , and characterized by spectroscopy, microscopy, and theory, react with ethylene at 298 K to form osmium glycol species or with CO to give osmium mono- and di-carbonyls. Os(=O)2 {-Osupport }1 or 2 is the precursor of a CO oxidation catalyst characterized by a turnover frequency of 4.0×10-3 (molecules of CO)/(Os atom×s) at 473 K; the active species are inferred to be osmium monocarbonyls. The structures and frequencies calculated at the level of density functional theory with the B3LYP functional bolster the experimental results and facilitate structural assignments. The lowest-energy structures have various osmium oxidation and spin states. The results demonstrate not only new chemistry of the supported single-site catalysts but also their complexity and the value of complementary techniques used in concert to unravel the chemistry.

PLATINOID MICROINCLUSIONS OF NATIVE OSMIUM GROUP IN ANCIENT GOLD ARTIFACTS FROM SIBERIA AND URALS AS A SOURCE OF GEOARCHAEOLOGICAL INFORMATION

The analysis of Early Iron Age gold jewelry from Hankarinsky Dol and Inskoy Dol in the Altai, Arzhan II royal mound in Tuva, and Filippovka I and II royal mounds in the Southern Urals, has detected platinoid inclusions similar to those in artifacts from the Near East. Their morphology and composition suggest that gold was mined from placer deposits located near the gold and platinum bearing ultramafi c belts. Microinclusions consist of solid solutions of osmium, iridium, and ruthenium. Their nomenclature was evaluated by the proportion of these components. Triangular plots of microinclusions in artifacts from the Urals reveal four clusters: principal (ruthenium and iridium-osmium) and secondary (osmium-ruthenium and iridium-ruthenium), the latter relating to nanoscale particles surrounding larger ones. Their emergence is due to the impact of gold melt on microinclusions. During melting, heated air in micropores could cause oxidation of osmium with subsequent assimilation of oxidation products by melt. Micropores, 1–0.4 μ in size, were revealed in 5–10 %. This should be taken into account when comparing the composition of microinclusions and minerals from tentative placer sources. Artifacts from Siberia show a mostly ruthenium tendency. Osmium-ruthenium and iridium-osmium trends were also detected, but not the iridium-ruthenium trend, possibly due to small sample size relating to Siberia. The presence of PGE microinclusions in ancient gold artifacts may suggest that these were manufactured locally.

Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO3, LiOsO3, and Na2OsO4, were successfully grown under high-pressure and high-temperature conditions at 6GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal–insulator transition in NaOsO3, a ferroelectric-like transition in LiOsO3, and high-temperature ferrimagnetism driven by a local structural distortion in Ca2FeOsO6 may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices.

ChemInform Abstract: Stereochemical Investigation and Total Synthesis of Inuloidin, a Biologically Active Sesquiterpenoid from Heterotheca inuloides.

Abstract The stereochemistry of inuloidin (1), which was a sesquiterpenoid that was characterized as a plant growth inhibitory substance from Heterotheca inuloides, was investigated. The modified Mosher's method coupled with a total synthetic study using osmium oxidation and Burgess dehydration as key steps were performed to clarify the stereochemistry of 1, which was determined to be a 2S,4R isomer.

Osmium dimethyl sulfoxide complexes: Synthesis and properties of [H(dmso)2][OsIII(dmso)2Br4

The reaction of H2[OsBr6] with DMSO in ethanol solution resulted in DMSO complex [H(dmso-O)2][OsIII(dmso-S)2Br4] (1) described previously as an intermediate product in the reaction of K2[OsBr6] with DMSO and characterized by EAS and ESR spectra. The coordination of DMSO molecules was established by IR and 1H and 13C NMR spectroscopy. The oxidation state of osmium and trans arrangement of DMSO molecules in the anion were established by ESR. The behavior of complex 1 in solutions was studied by EAS, ESR, and mass-spectrometry: a displacement of Br− ions accompanied by the reduction of osmium to oxidation state +2 occurs in DMSO, a solvation with displacement of DMSO molecules is observed at the first stage in water and methanol (rate constants 2.3 × 10−4 and 1.7 × 10−3 s−1, respectively), the sequential substitution of DMSO molecules and osmium oxidation to form [OsIVBr6]2− ions takes place in 4 mol/L HBr.

酸化オスミウム（VIII）を含む電子顕微鏡試料作製廃液の再生に関する研究

酸化オスミウム（VIII）を含む電子顕微鏡試料作製廃液の再生に関する研究

Stereochemical investigation and total synthesis of inuloidin, a biologically active sesquiterpenoid from Heterotheca inuloides

The stereochemistry of inuloidin (1), which was a sesquiterpenoid that was characterized as a plant growth inhibitory substance from Heterotheca inuloides, was investigated. The modified Mosher's method coupled with a total synthetic study using osmium oxidation and Burgess dehydration as key steps were performed to clarify the stereochemistry of 1, which was determined to be a 2S,4R isomer.

A glance at the reactivity of osma(II)cycles [Os(C–N)x(bpy)3 − x]m + (x = 0–3) Covering a 1.8 V Potential Range toward Peroxidase through Monte Carlo Simulations (−C–N = o-2-phenylpyridinato, bpy = 2,2′-bipyridine)

Three cyclometalated and one coordination compounds [Os(C–N)x(bpy)3−x]m (x/m=0/2+ (4); 1/1+ (3); 2/1+ (2); 3/0 (1); −C–N=2-phenylpyridinato, bpy=2,2′-bipyridine) with drastically different reduction potentials have been used for analyzing the second-order rate constants for one-electron, metal-based osmium(II) to osmium(III) oxidation of the complexes by compound I (k2) and compound II (k3) of horseradish peroxidase. Previously unknown k2 and k3 have been determined by digital simulation of cyclic voltammograms measured in phosphate buffer of pH7.6 and 21±1°C. Osmium(II) species derived from osmium(III) complexes 1 and 2 were generated electrochemically in situ. Under the conditions used the reduction potentials for the OsIII/II feature equal −0.90, −0.095, 0.23 and 0.85V versus NHE (normal hydrogen electrode) for 1–4, respectively. The rate constants k2 equal ~5×107, 6×108, 2×106 and 1×105M−1s−1 and the rate constants k3 equal ~9×106, 4×107, 1×106 and 1×105M−1s−1 for complexes 1–4, respectively. Both rate constants k2 and k3 first increase with increasing the reaction driving force on going from 4 to 2 but then both decrease on going to complex 1 though the reaction driving force is the highest in this case. The system described has been explored theoretically using docking Monte Carlo simulations.