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Sample records for cobalt ii oxinate

  1. Gravimetric determination of beryllium with sodium oxinate.

    PubMed

    Hundekar, A M; Umapathy, P; Sen, D N

    1978-04-01

    Sodium oxinate is found to precipitate Be(II) quantitatively in the pH range 7.5-8.2. The complex has the composition Be(2)O(C(9)H(6)NO)(2).2H(2)O, is stable and can be weighed directly after drying at 105-110 degrees . A method for the estimation of Be(II) and its separation from interfering elements is described. The monohydrate has been prepared from the dihydrate and characterized. The results show the presence of hydroxyl bridges in the monohydrate. Methods using various organic reagents for the direct estimation of beryllium in ores and alloys have been examined and it is found that 4-chloro-2,5-dimethoxyacetoacetanilide gives the best results. A method for the determination of be(II) in beryl without prior separation of Fe(III) and Al(III) is described.

  2. Cobalt(II) and Cobalt(III) Coordination Compounds.

    ERIC Educational Resources Information Center

    Thomas, Nicholas C.; And Others

    1989-01-01

    Presents a laboratory experiment which illustrates the formation of tris(phenanthroline)cobalt complexes in the 2+ and 3+ oxidation states, the effect of coordination on reactions of the ligand, and the use of a ligand displacement reaction in recovering the transformed ligand. Uses IR, UV-VIS, conductivity, and NMR. (MVL)

  3. Cobalt(II) complexes with hydroxypyridines and halogenides

    NASA Astrophysics Data System (ADS)

    Dojer, Brina; Pevec, Andrej; Jagličić, Zvonko; Kristl, Matjaž

    2017-01-01

    We have synthesized and characterized two new cobalt(II) complexes: difluoridotetrakis(3-hydroxypyridine-κN)cobalt(II), [CoF2(C5H5NO)4] (1) and hexa(2-pyridone-κO)cobalt(II) tetrachloridocobaltate(II), [Co(C5H5NO)6][CoCl4] (2). The complexes were prepared by solvothermal synthesis. A methanol solution of hydroxypyridine was added to water solution of cobalt(II) acetate dihydrate followed by a few drops of concentrated hydrofluoric or hydrochloric acid into the mixture. The crystals of the compounds 1 and 2 are stable on air. The compounds were characterized structurally by single-crystal X-ray diffraction analysis, spectrally by FT-IR spectroscopy and thermally. Thermal analysis showed that the final product of both complexes after heating to 900 °C is elemental cobalt. The interactions between building units in the crystal structures include intra- and intermolecular hydrogen bonds in both compounds and π-π interactions in compound 2.

  4. Analysis of cobalt(II) in 2-(5-cyanotetrazolato)pentaammine cobalt(III) perchlorate

    SciTech Connect

    Schumacher, R.J.; Brown, N.E.; Deutsch, E.A.

    1985-10-30

    A new method of analysis is described for cobalt(II) complexes in 2-(5-cyanotetrazolato)pentaammine cobalt(III) perchlorate. The color reagent is 2,2'-dipyridyl-2-pyridyl hydrazone (DPPH), which complexes with the Co(II) and is oxidized to a substitution inert Co(III) (DPPH)/sub 2/ complex. Interferences from other ions is not a problem because the complex is stable at pH 2 - where complexes formed between DPPH and other ions are not stable. The usual air oxidant in this type of analysis has been replaced with ammonium peroxydisulfate improving both the precision and accuracy. The Sandell sensitivity is 0.0015 ..mu..g Co(II)/cm/sup 2/. The system obeys Beer's Law up to 4 ..mu..g in Co(II)mL of solution and has a molar absorptivity of 3.9 x 10/sup 4/ L/mole cm at 514 nm. The procedure was used to determine the degree of decomposition in samples that had undergone partial thermal decomposition. 11 refs., 4 figs., 6 tabs.

  5. Cobalt(II) selective membrane electrode based on palladium(II) dichloro acetylthiophene fenchone azine.

    PubMed

    Isa, I M; Mustafar, S; Ahmad, M; Hashim, N; Ghani, S A

    2011-12-15

    A new cobalt(II) ion selective electrode based on palladium(II) dichloro acetylthiophene fenchone azine(I) has been developed. The best membrane composition is found to be 10:60:10:21.1 (I)/PVC/NaTPB/DOP (w/w). The electrode exhibits a Nerstian response in the range of 1.0 × 10(-1)-1.0 × 10(-6)M with a detection limit and slope of 8.0 × 10(-7)M and 29.6 ± 0.2 mV per decade respectively. The response time is within the range of 20-25s and can be used for a period of up to 4 months. The electrode developed reveals good selectivity for cobalt(II) and could be used in pH range of 3-7. The electrode has been successfully used in the determination of cobalt(II) in water samples.

  6. Cobalt.

    PubMed

    Fowler, Joseph F

    2016-01-01

    Cobalt has been a recognized allergen capable of causing contact dermatitis for decades. Why, therefore, has it been named 2016 "Allergen of the Year"? Simply put, new information has come to light in the last few years regarding potential sources of exposure to this metallic substance. In addition to reviewing some background on our previous understanding of cobalt exposures, this article will highlight the recently recognized need to consider leather as a major site of cobalt and the visual cues suggesting the presence of cobalt in jewelry. In addition, a chemical spot test for cobalt now allows us to better identify its presence in suspect materials.

  7. Cobalt

    SciTech Connect

    1993-02-01

    Cobalt is typical a by- or co-product with copper or nickel. The average crustal abundance of cobalt is 23 pans per million. Cobalt-containing minerals include cobaltite, skutterudite, and linnaeite. Due to the diversity of cobalt deposits, several techniques are used to extract the ore. The copper/cobalt-bearing ores of Zaire are extracted by open pit and underground methods. In Zambia, similar deposits are mined using modified sublevel, and cut-and-fill underground stoping methods. The sulfide and oxide ore concentrates mined in Zaire are roasted and leached in sulfuric acid. Copper is subsequently recovered by electrolysis, and cobalt is precipitated in the form of a hydrate. Finally, the hydrate is dissolved in acid and cobalt is recovered by electrolysis.

  8. [Study on the thermodynamical molar absorptivity of the interaction of cobalt(II) and the histidine].

    PubMed

    Chen, L; Zhang, D; Yang, D; He, Z; Wang, Y

    1999-02-01

    In this paper UV-Vis absorption spectrum of Cobalt(II) with the histidine and the thermodynamical molar absorptivity of the complex reaction were determined and the complexes of Cobalt(II) with the histidine were compared in terms of stability.

  9. Cobalt

    SciTech Connect

    Fox, G.J.

    1994-12-01

    Traditionally, cobalt has been well-known for its chemical uses, including pigments used in ceramic glazes that create the popular cobalt blue color derived from cobalt aluminate. Because of its diverse physical properties, the element is linked to many other applications, including superalloys, permanent magnets, and chemical catalysts. Cobalt 60, a radioisotope of cobalt, continues to be a contributor to the success of high-technology advancements, including innovations in medical treatments. Typically a by-product of copper and nickel production, significant cobalt reserves are found in only a few countries. The African countries of Zaire and Zambia, as well as Canada, are leading cobalt producers. Although the USA is the world's largest consumer, accounting for about one-third of total consumption, it has no domestic production and relies solely upon foreign imports to satisfy demand. The world market has been plagued with the effects of economic and political factors throughout the years, and consequently, price instability has been common. Presently, supply and demand are moving toward a closer balance, and lower market prices are expected within the next year.

  10. Biosorption of copper(II) and cobalt(II) from aqueous solutions by crab shell particles.

    PubMed

    Vijayaraghavan, K; Palanivelu, K; Velan, M

    2006-08-01

    Biosorption of each of the heavy metals, copper(II) and cobalt(II) by crab shell was investigated in this study. The biosorption capacities of crab shell for copper and cobalt were studied at different particle sizes (0.456-1.117 mm), biosorbent dosages (1-10 g/l), initial metal concentrations (500-2000 mg/l) and solution pH values (3.5-6) in batch mode. At optimum particle size (0.767 mm), biosorbent dosage (5 g/l) and initial solution pH (pH 6); crab shell recorded maximum copper and cobalt uptakes of 243.9 and 322.6 mg/g, respectively, according to Langmuir model. The kinetic data obtained at different initial metal concentrations indicated that biosorption rate was fast and most of the process was completed within 2h, followed by slow attainment of equilibrium. Pseudo-second order model fitted the data well with very high correlation coefficients (>0.998). The presence of light and heavy metal ions influenced the copper and cobalt uptake potential of crab shell. Among several eluting agents, EDTA (pH 3.5, in HCl) performed well and also caused low biosorbent damage. The biosorbent was successfully regenerated and reused for five cycles.

  11. Determination of cobalt(II)-EDTA, cobalt(III)-EDTA, and cobalt(II) in an aqueous solution

    SciTech Connect

    Ayres, D.M.; Davis, A.P.

    1996-11-01

    The determination of Co-EDTA species is critical to the understanding of radionuclide migration in the environment, as well as determining efficiencies of various complexed-Co treatment technologies. A new, simple column-oxidation separation methodology was devised to determine the fraction of uncomplexed Co(II), Co(II)-EDTA, and Co(III)-EDTA in an aqueous mixture. A Dowex 50W (H{sup +}) ion-exchange resin, and the oxidative conversion of residual Co(II)-EDTA to Co(III)-EDTA using H{sub 2}O{sub 2}, allowed the separation of species fractions. Only atomic absorption spectrophotometric measurements were required after separation of the fractions. Analysis of individual Co species separated from mixtures ranging in concentration from 3 {times} 10{sup {minus}5} to 3 {times} 10{sup {minus}3} M total Co resulted in average recoveries of 97 {plus_minus} 4%. 15 refs., 2 tabs.

  12. Leukemic cell labeling with indium-111-oxine

    SciTech Connect

    Uchida, T.; Takagi, Y.; Matsuda, S.; Yui, T.; Ishibashi, T.; Kimura, H.; Kariyone, S.

    1984-01-01

    Leukemic cells were labeled with In-111-oxine in patients with acute leukemia. In vitro labeling studies revealed that labeling efficiency reached maximum 80.8 +- 3.6% (mean +- 1SD) by 2 times washes after 20 minutes incubation time. Cell viability was assessed by trypan blue exclusion test and in vitro culture of leukemic cells, which showed no cellular damage during labeling procedure. Elution of In-111 from the labeled cells was 10.0 +- 1.2% at 12 hours after labeling. For in vivo leukemic cell kinetic studies, more than 10/sup 8/ leukemic cells separated from Ficoll-Hypacque sedimentation were labeled by 30 minutes of In-111-oxine incubation and two times washes at 37/sup 0/C. In vivo studies were performed in 7 patients with acute myeloblastic, lymphoblastic leukemia and blastic crisis of chronic myelocytic leukemia. Labeled leukemic cells disappeared in single exponential fashion with half life of 9.6 to 31.8 hours. Total leukemic cell pool in peripheral circulation was calculated, which correlated well with peripheral leukemic cell counts (r=0.99). No relationship was observed between total leukemic cell pool and leukemic cell turnover rate. Migration patterns of labeled leukemic cells showed that pulmonary uptake was evident within 15 minutes after the infusion and returned to base-line. Splenic and hepatic uptake showed gradual increase up to 24 hours. Bone marrow accumulation was shown only in 2 cases. Presently, there are no suitable radionuclides for leukemic cell labeling. In-111-oxine labeled leukemic cells would overcome this difficulty.

  13. Structure of catabolite activator protein with cobalt(II) and sulfate

    SciTech Connect

    Rao, Ramya R.; Lawson, Catherine L.

    2014-04-15

    The crystal structure of E. coli catabolite activator protein with bound cobalt(II) and sulfate ions at 1.97 Å resolution is reported. The crystal structure of cyclic AMP–catabolite activator protein (CAP) from Escherichia coli containing cobalt(II) chloride and ammonium sulfate is reported at 1.97 Å resolution. Each of the two CAP subunits in the asymmetric unit binds one cobalt(II) ion, in each case coordinated by N-terminal domain residues His19, His21 and Glu96 plus an additional acidic residue contributed via a crystal contact. The three identified N-terminal domain cobalt-binding residues are part of a region of CAP that is important for transcription activation at class II CAP-dependent promoters. Sulfate anions mediate additional crystal lattice contacts and occupy sites corresponding to DNA backbone phosphate positions in CAP–DNA complex structures.

  14. Synthesis, Characterization, and Use of a Cobalt(II) Complex as an NMR Shift Reagent.

    ERIC Educational Resources Information Center

    Goff, Harold M.; And Others

    1982-01-01

    Describes procedures for preparing acetylacetonate complex of cobalt(II), followed by spectrophotometric analysis to characterize the material, with additional characterization methods supplied by students to provide open-ended dimension for the experiment. (SK)

  15. [Study on the interaction of cobalt (II) polyamidomine dendrimer with DNA by spectrometry techniques].

    PubMed

    Li, Jin-Huan; Ai, Shi-Yun; Shi, Wei-Jie; Yin, Huan-Shun; Du, Hong-Xia

    2009-03-01

    Cobalt (II) polyamidomine dendrimer was prepared by the reaction of cobalt chloride, glyoxal and polyamidomine dendrimer of 5.0 generation. The interaction of cobalt (II) polyamidomine dendrimer complex with herring sperm (hsDNA) was carried out using methylene blue (MB) as the probe molecule by absorption and fluorescence spectroscopy and synchronous fluorescence spectroscopy. The results showed that the intensity of absorption peaks and fluorescence peaks increased when the complex interacted with hsDNA. The effect of sodium chloride showed that sodium ion can significantly constrain the interaction of cobalt(II) polyamidomine dendrimer with hsDNA. The curves indicated the competitive inhibition of MB binding to hsDNA in the presence of cobalt (II) polyamidomine dendrimer complexes, also MB could insert into interior of cobalt (II) polyamidomine dendrimer complexes. The results suggested that the complex mainly interacted with negatively charged phosphate moieties on hsDNA through electrostatic attraction and stacked on the surface of double stranded hsDNA, which may reduce the binding affinity of MB to hsDNA in the surrounding site. It was indicated that sodium ion might neutralize the negatively charged phosphate backbone of hsDNA, and then weaken the electrostatic attraction between complexes and hsDNA.

  16. Synthesis, characterization, and photoactivated DNA cleavage by copper (II)/cobalt (II) mediated macrocyclic complexes.

    PubMed

    Naik, H R Prakash; Naik, H S Bhojya; Aravinda, T; Lamani, D S

    2010-01-01

    We report the synthesis of new photonuclease consisting of two Co(II)/Cu(II) complexes of macrocyclic fused quinoline. Metal complexes are [MLX(2)], type where M = Co(II) (5), Cu(II) (6), and X = Cl, and are well characterized by elemental analysis, Fourier transform infrared spectroscopy, (1)H-NMR and electronic spectra. We have shown that photocleavage of plasmid DNA is markedly enhanced when this ligand is irradiated in the presence of Cu(II), and more so than that of cobalt. The chemistry of ternary and binary Co(II) complexes showing efficient light induced (360 nm) DNA cleavage activity is summarized. The role of the metal in photoinduced DNA cleavage reactions is explored by designing complex molecules having macrocyclic structure. The mechanistic pathways are found to be concentration dependent on Co(II)/Cu(II) complexes and the photoexcitation energy photoredox chemistry. Highly effective DNA cleavage ability of 6 is attributed to the effective cooperation of the metal moiety.

  17. Carbene radicals in cobalt(II)-porphyrin-catalysed carbene carbonylation reactions; a catalytic approach to ketenes.

    PubMed

    Paul, Nanda D; Chirila, Andrei; Lu, Hongjian; Zhang, X Peter; de Bruin, Bas

    2013-09-23

    One-pot radicals: Cobalt(III)-carbene radicals, generated by metallo-radical activation of diazo compounds and N-tosylhydrazone sodium salts with cobalt(II) complexes of porphyrins, readily undergo radical addition to carbon monoxide, allowing the catalytic production of ketenes. These ketenes subsequently react with various amines, alcohols and imines in one-pot tandem transformations to produce differently substituted amides, esters and β-lactams in good isolated yields.

  18. Cobalt (II) β-diketonate adducts as new precursors for the growth of cobalt oxide films by liquid injection MOCVD

    NASA Astrophysics Data System (ADS)

    Pasko, S.; Abrutis, A.; Hubert-Pfalzgraf, L. G.; Kubilius, V.

    2004-02-01

    New metalorganic compounds—adducts of cobalt(II) acetylacetonate (acac) and cobalt(II) 2,2,6,6-tetramethyl-3,5-heptanedionate (thd) with N,N,N',N'-tetramethyl-1,2-diaminoethane have been synthesized and studied as potential precursors for liquid injection metalorganic chemical vapor deposition of Co 3O 4 films. The properties of the films were compared with those deposited using standard [Co(acac) 2] 4 and Co(thd) 2 precursors. Depositions were carried out at 350-600°C on LaAlO 3 (1 0 0), sapphire (R-plane), MgO (1 0 0) and Si (1 0 0) substrates. The films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy. Depending on substrate material, highly (1 1 0) or (1 0 0) textured Co 3O 4 films have been deposited; moreover, films exhibited preferential in-plane orientation. No significant difference has been found in the quality of Co 3O 4 films deposited from different precursors.

  19. Solvent effects on the stability of nifuroxazide complexes with cobalt(II), nickel(II) and copper(II) in alcohols.

    PubMed

    Khan, Mustayeen A; Ali, S Kauser; Bouet, Gilles M

    2002-05-21

    A spectrophotometric study of the complexation of nifuroxazide with cobalt(II), nickel(II) and copper(II) was carried out in different alcohols. The formation of a complex in each case is reported and their stability constants have been calculated. For a given solvent, the stability of the complexes increases from cobalt to copper. In the case of copper(II), the stability varies as an inverse function of the dielectric constant of the solvent. A possible structure of the complex is proposed.

  20. Aggregation of Cobalt (II) Tetrasulfonated Phthalocyanine in Methanol- Water Solutions

    DTIC Science & Technology

    1983-06-01

    dimerization at either 250 or 280 C. Helper observed the same irregular features in the thermodynamics of the ioniza- tion of acetic and chloroacetic acids in...4, 1-95 (1975). 70. Miller, F.J., Wu, C., and Hepler, L.G. Thermodynamics of Ionization of Acetic and Chloroacetic Acids in Ethanol-Water Mixtures. J...of 4-sulfophthalic acid , ammonium chloride, urea, ammonium molybdate, and cobalt sulfate heptahydrate in hot nitrobenzene. The purifi- cation

  1. Monomeric square-planar cobalt(II) acetylacetonate: mystery or mistake?

    PubMed

    Vreshch, Volodimir D; Yang, Jen-Hsien; Zhang, Haitao; Filatov, Alexander S; Dikarev, Evgeny V

    2010-09-20

    No evidence was found for the existence of a previously reported mononuclear square-planar form of unsolvated cobalt(II) acetylacetonate, Co(acac)(2), in all samples that have been obtained by using a variety of preparative techniques and crystallization conditions. It was confirmed that the structure of tetramer Co(4)(acac)(8), reported back in 1964 by Cotton and Elder, is correct, the synthesis is reproducible, and the bulk material corresponds to single-crystal data. Additionally, the title compound can be isolated in tetranuclear form by reducing cobalt(III) acetylacetonate with cobalt metal in solvent-free conditions or by crystallization from a hexanes solution. At the same time, from noncoordinating halogenated solvents, Co(acac)(2) crystallizes as a trinuclear core molecule, in which all Co atoms also exhibit octahedral coordination. From coordinating solvents such as ethanol, cobalt(II) acetylacetonate was found to appear in the form of its bis-adduct Co(acac)(2)(EtOH)(2). On the basis of observations made in this work and the details presented in the original paper, we suggest that the reported mononuclear structure of square-planar acetylacetonate should likely contain copper instead of cobalt.

  2. Study of the influence of the bridge on the magnetic coupling in cobalt(II) complexes.

    PubMed

    Fabelo, Oscar; Cañadillas-Delgado, Laura; Pasán, Jorge; Delgado, Fernando S; Lloret, Francesc; Cano, Joan; Julve, Miguel; Ruiz-Pérez, Catalina

    2009-12-07

    Two new cobalt(II) complexes of formula [Co(2)(bta)(H(2)O)(6)](n) x 2nH(2)O (1) and [Co(phda)(H(2)O)](n) x nH(2)O (2) [H(4)bta = 1,2,4,5-benzenetetracarboxylic acid, H(2)phda = 1,4-phenylenediacetic acid] have been characterized by single crystal X-ray diffraction. Compound 1 is a one-dimensional compound where the bta(4-) ligand acts as 2-fold connector between the cobalt(II) ions through two carboxylate groups in para-conformation. Triply bridged dicobalt(II) units occur within each chain, a water molecule, a carboxylate group in the syn-syn conformation, and an oxo-carboxylate with the mu(2)O(1);kappa(2)O(1),O(2) coordination mode acting as bridges. Compound 2 is a three-dimensional compound, where the phda(2-) group acts as a bridge through its two carboxylate groups, one of them adopting the mu-O,O' coordination mode in the syn-syn conformation and the other exhibiting the single mu(2)-O'' bridging mode. As in 1, chains of cobalt(II) ions occur in 2 with a water molecule, a syn-syn carboxylate group, and an oxo-carboxylate constitute the triply intrachain bridging skeleton. Each chain is linked to other four ones through the phda(2-) ligand, giving rise to the three-dimensional structure. The values of the intrachain cobalt-cobalt separation are 3.1691(4) (1) and 3.11499(2) A (2) whereas those across the phenyl ring of the extended bta(4-) (1) and phda(2-) (2) groups are 10.1120(6) and 11.4805(69 A, respectively. The magnetic properties of 1 and 2 have been investigated in the temperature range 1.9-300 K, and their analysis has revealed the occurrence of moderate intrachain ferromagnetic couplings [J = +5.4 (1) and +2.16 cm(-1) (2), J being the isotropic magnetic coupling parameter], the magnetic coupling through the extended bta(4-) and phda(2-) with cobalt-cobalt separations larger than 10 A being negligible. The nature and magnitude of the magnetic interactions between the high-spin cobalt(II) ions in 1 and 2 are compared to those of related systems and

  3. Equilibrium studies of cobalt(II) extraction with 2-pyridineketoxime from mixed sulphate/chloride solution.

    PubMed

    Wieszczycka, Karolina; Krupa, Marta; Wojciechowska, Aleksandra; Wojciechowska, Irmina; Olszanowski, Andrzej

    In present paper the equilibrium of cobalt extraction with 1-(2-pyridyl)tridecan-1-one oxime from the chloride/sulphate solutions was studied. The presented results indicated that extraction depends on a number of process variables, including the pH, metal and Cl(-) concentration in the aqueous feed, and concentration of the oxime in the organic phase. The created cobalt-complexes with the 2-pyridine ketoxime were stable and only concentrated HCl was found to be a suitable stripping agent for coordinated metal. The separation of Co(II) from Zn(II), Ni(II) and Cu(II) was also studied, but the selective recovery of the metals was possible using the multi-stage stripping process.

  4. Method for labelling leucocytes with indium In-111 oxine

    SciTech Connect

    Kaminsky, D.

    1992-03-03

    This patent describes an improved method for radio-labelling leucocytes with Indium In-111 oxine. It comprises separating the leucocytes from whole blood for obtaining separated leucocytes mixed with residual red blood cells; and then labelling the separated leucocytes with Indium In-111 oxine; wherein the improvement comprises the following further step: depleting residual red blood cells from the separated leucocytes by resuspending the leucocytes in an isotonic saline solution, then rocking the resuspended leucocytes for causing the leucocytes to preferentially settle out, and then removing residual red blood cells which remain suspended within the supernatant isotonic saline solution.

  5. Characterization of cobalt(II) chloride-modified condensation polyimide films

    NASA Technical Reports Server (NTRS)

    Rancourt, J. D.; Taylor, L. T.

    1988-01-01

    The effect of solvent extraction on the properties of cobalt(II) chloride-modified polyimide films was investigated. Solvent-cast films were prepared from solutions of cobalt chloride in poly(amide acid)/N,N-dimethylacetamide (DMAc) and were subsequently dried and cured in static air, forced air, or inert gas ovens with controlled humidity. The films were extracted by either of the three processes (1) soaking in a tray with distilled water at room temperature, (2) soxhlett extraction with distilled water, or (3) soxhell extraction with DMAc. Extraction with DMAc was found to remove both cobalt and chlorine from the films and to slightly increase bulk thermal stability and both surface resistivity and electrical resistivity.

  6. Synthesis, crystal structure and magnetic property of a new cobalt(II) vanadate

    SciTech Connect

    Zhang, Su-Yun; Guo, Wen-Bin; Yang, Ming; Tang, Ying-Ying; Wang, Nan-Nan; Huang, Rong-Rong; Cui, Mei-Yan; He, Zhang-Zhen

    2015-05-15

    A new cobalt(II) vanadate has been synthesized by hydrothermal reaction. It exhibits 3D cobalt(II) oxide architecture with Co{sub 12} member ring (MR) and Co{sub 6} MR tunnels along c-axis. V(2)O{sub 4} tetrahedra are located at the center of Co{sub 6}-MR tunnels whereas V(1)O{sub 4} tetrahedra and ‘isolated’ 1D Co(1)O{sub 6} octahedral chains are located at the Co{sub 12}-MR tunnels. The 3D cobalt(II) oxide architecture is constructed on irregular ladder chains formed by edge- and face-sharing of Co(2)O{sub 6} octahedra whereas the ‘isolated’ 1D Co(1)O{sub 6} octahedral chain in the tunnels are formed by face-sharing of Co(1)O{sub 6} octahedra. Magnetic property is investigated by means of magnetic susceptibility, magnetization and heat capacity measurement. Magnetic susceptibility and heat capacity measurement indicate a typical long-range spin-canting antiferromagnetic ordering below ~71 K; metamagnetic behavior was detected in the isothermal magnetization measurement at 2 K. - Graphical abstract: A cobalt(II) vanadate, Co{sub 7}V{sub 4}O{sub 16}(OH){sub 2}(H{sub 2}O) has been synthesized and structurally characterized. It exhibits antiferromagnetic interaction with weak spin-canting below ~71 K; metamagnetic behavior was detected in isothermal magnetization at 2 K. - Highlights: • Hydrothermal reaction of CoCl{sub 2}·6H{sub 2}O and Na{sub 3}VO{sub 4} yielded a new cobalt(||) vanadate. • It shows novel structure since its large Co/V ratio. • It shows long-range spin-canting antiferromagnetic ordering below ~71 K. • Metamagnetic behavior was detected in the isothermal magnetization at 2 K.

  7. Sol-gel synthesized adsorbents for mercury(II), chromium(III) and cobalt(II) separations

    NASA Astrophysics Data System (ADS)

    Nam, Kwan-Hyun

    Novel organo-ceramic adsorbents are synthesized and characterized for mercury(II), chromium(III) and cobalt(II) separations from aqueous streams. Mercury(II) adsorption on thiol functional adsorbents (SOL-AD-IV) is studied for two systems: (1) coal-fired utility plant scrubber water, and (2) acidic nuclear wastes. To exemplify the removal of mercury from these systems, simulants are prepared and used. Results show that the mercury adsorption capacity is higher than reported in the literature. In addition, the adsorbent exhibits high adsorption capacity even at 4 M HNO3. In column operation, flow rates as high as 1100 BV/h could be employed with effluent concentrations reaching below 0.06 mug/L. This adsorbent is found to exhibit superior mercury adsorption characteristics with a demonstrated long life cycle. Chromium(III) and cobalt(II) adsorption is evaluated using phosphonic acid (SOL-PHONIC) and phosphinic acid (SOL-PHINIC) functional adsorbents synthesized via sol-gel processing by co-condensation of clusters of functional precursor (FPS) and cross-linking (CA) silanes. Nuclear magnetic resonance (NMR) spectroscopy is used to examine the evolution of oligomeric species with hydrolysis and condensation reaction times. The effects of both the FPS and CA oligomeric species on the physicochemical properties of the resulting adsorbent materials are evaluated and explained in terms of structural and adsorption capacity characteristics. The adsorbents are further characterized by solid-state NMR spectroscopy to elucidate the incorporation of the FPS and the nature of the functional groups in the adsorbent matrix. SOL-PHONIC is employed for the removal of chromium, and both SOL-PHONIC and SOL-PHINIC are employed for the removal of cobalt. Results show that chromium and cobalt adsorptions are solution pH dependent. Cobalt adsorption tests evaluated using the two adsorbents show that SOL-PHONIC exhibits a higher selectivity towards cobalt over nickel. The adsorption

  8. Copper(II)-8-hydroxquinoline coprecipitation system for preconcentration and separation of cobalt(II) and manganese(II) in real samples.

    PubMed

    Soylak, Mustafa; Kaya, Betul; Tuzen, Mustafa

    2007-08-25

    A separation-preconcentration procedure based on the coprecipitation of cobalt(II) and manganese(II) ions with copper(II)-8-hydroxquinoline system has been developed. The analytical parameters including pH, amount of copper(II) as carrier element, amount of 8-hydroxquinoline, sample volume, etc., was investigated for the quantitative recoveries of Co(II) and Mn(II). No interferic effects were observed from the concomitant ions which are present in real samples. The detection limits for analyte ions by three sigma criteria were 0.86microgL(-1) for cobalt and 0.98microgL(-1) for manganese. The validation of the presented preconcentration procedure was performed by the analysis of NIST SRM 2711 Montana soil and GBW 07605 Tea certified reference materials. The procedure presented was applied to the analyte contents of real samples including natural waters and some food samples with successfully analytical results.

  9. A bio-inspired switch based on cobalt(II) disulfide/cobalt(III) thiolate interconversion.

    PubMed

    Gennari, Marcello; Gerey, Bertrand; Hall, Nikita; Pécaut, Jacques; Collomb, Marie-Noëlle; Rouzières, Mathieu; Clérac, Rodolphe; Orio, Maylis; Duboc, Carole

    2014-05-19

    Disulfide/thiolate interconversion supported by transition-metal ions is proposed to be implicated in fundamental biological processes, such as the transport of metal ions or the regulation of the production of reactive oxygen species. We report herein a mononuclear dithiolate Co(III) complex, [Co(III)LS(Cl)] (1; LS=sulfur containing ligand), that undergoes a clean, fast, quantitative and reversible Co(II) disulfide/Co(III) thiolate interconversion mediated by a chloride anion. The removal of Cl(-) from the Co(III) complex leads to the formation of a bis(μ-thiolato) μ-disulfido dicobalt(II) complex, [Co2(II,II)LSSL](2+) (2(2+)). The structures of both complexes have been resolved by single-crystal X-ray diffraction; their magnetic, spectroscopic, and redox properties investigated together with DFT calculations. This system is a unique example of metal-based switchable M(n)2-RSSR/2 M((n+1))-SR (M=metal ion, n=oxidation state) system that does not contain copper, acts under aerobic conditions, and involves systems with different nuclearities.

  10. Local structure studies of some cobalt (II) complexes using extended X-ray absorption fine structure

    NASA Astrophysics Data System (ADS)

    Mishra, Ashutosh; Ninama, Samrath; Trivedi, Apurva

    2014-09-01

    Extended X-ray Absorption Fine Structure (EXAFS) analysis of Cobalt (II) complex as a ligand of 2 -methyl-3-[(bis-aniline(R) phenyl]-3H-l,5 benzodiazepine for finding local structure using conventional method .The Co(II) complexes were prepared by chemical root method. The EXAFS spectra were recorded at Cobalt K-edge i.e.; 7709 eV using Dispersive EXFAS beam line at 2.5GeV Indus-2 Synchrotron Radiation Source(SRS) at RRCAT, Indore, India. The recorded EXAFS data were analysed using the computer software Athena for determine the nearest neighbouring distances (bond lengths) of these complexes with conventional methods and it compared with Fourier transform(FT) analysis. The Fourier Transform convert EXAFS data signal into r-space or k-space. This is useful for visualizing the major contributions to the EXAFS spectrum.

  11. Nitrous oxide activation by a cobalt(ii) complex for aldehyde oxidation under mild conditions.

    PubMed

    Corona, Teresa; Company, Anna

    2016-10-07

    Nitrous oxide (N2O) is a waste gas produced in many industrial processes with an important environmental impact. Thus, its application as an oxidant is highly desirable because it produces innocuous N2 as a by-product. In this work we report a new cobalt(ii) complex that reacts with N2O under mild conditions and the catalytic application of this system to carry out the oxidation of aldehydes.

  12. A highly selective and sensitive fluorescence assay for determination of copper(II) and cobalt(II) ions in environmental water and toner samples.

    PubMed

    Tsai, Chia-Yi; Lin, Yang-Wei

    2013-02-21

    In this study, a highly selective and sensitive fluorescence assay has been proposed for the determination of copper(II) and cobalt(II) ions in environmental water and toner samples. In the presence of hydrogen peroxide, copper(II) reacted with a new fluorescence reagent Amplex® UltraRed (AUR), forming a fluorescence product only at pH 7.0, while the fluorescence product of cobalt(II) with AUR formed only at pH 9.0. The fluorescence signal obtained was linear with respect to the copper(II) concentration over the range of 1.6-12.0 μM (R(2) = 0.988) and was linear with respect to the cobalt(II) concentration over the range of 45.0 nM to 1.0 μM (R(2) = 0.992). The limits of detection (at a signal-to-noise ratio of 3) for copper(II) and cobalt(II) were 0.17 μM and 14.0 nM, respectively. Our present approach is simpler, faster, and more cost-effective than other techniques for the detection of copper(II) and cobalt(II) ions in environmental water samples and that of copper(II) ions in toner samples.

  13. Structural and magnetic properties of cobalt(II) complexes with pyridinecarboxamide ligands

    NASA Astrophysics Data System (ADS)

    Dojer, Brina; Pevec, Andrej; Belaj, Ferdinand; Jagličić, Zvonko; Kristl, Matjaž; Drofenik, Miha

    2014-11-01

    The synthesis and characterization of two new cobalt(II) coordination compounds with nicotinamide (nia) and isonicotinamide (isn) are reported. The products were characterized magnetically, structurally by single-crystal X-ray diffraction analysis and spectrally by FT-IR spectroscopy. Using the reaction of cobalt(II) acetate tetrahydrate and nicotinamide in methanol we obtained light-red crystals of the mononuclear complex [Co(nia)2(H2O)4](CH3COO)2·2H2O (1). The synthesis in a system cobalt(II) acetate dihydrathe, isonicotinamide and dimethylformamide-methanol mixture gave a new dinuclear coordination compound with the formula [Co2(CH3COO)4(isn)4]·2C3H7NO (2). In both compounds a trans arrangement of pyridinecarboxamide ligands was found. Intermolecular hydrogen bonds in the crystal structures of both complexes are discussed. The magnetic properties were studied between 2 K and 300 K giving the result μeff = 4.6 BM for 1 and μeff = 4.7 BM for 2 in the paramagnetic region.

  14. Synthesis, magnetic properties, and STM spectroscopy of cobalt(II) Cubanes [Co(II) (4)(Cl)(4)(HL)(4)].

    PubMed

    Scheurer, Andreas; Ako, Ayuk M; Saalfrank, Rolf W; Heinemann, Frank W; Hampel, Frank; Petukhov, Konstantin; Gieb, Klaus; Stocker, Michael; Müller, Paul

    2010-04-26

    Reaction of cobalt(II) chloride hexahydrate with N-substituted diethanolamines H(2)L(2-4) (3) in the presence of LiH in anhydrous THF leads under anaerobic conditions to the formation of three isostructural tetranuclear cobalt(II) complexes [Co(II) (4)(Cl)(4)(HL(2-4))(4)] (4) with a [Co(4)(mu(3)-O)(4)](4+) cubane core. According to X-ray structural analyses, the complexes 4 a,c crystallize in the tetragonal space group I4(1)/a, whereas for complex 4 b the tetragonal space group P$\\bar 4$ was found. In the solid state the orientation of the cubane cores and the formation of a 3D framework were controlled by the ligand substituents of the cobalt(II) cubanes 4. This also allowed detailed magnetic investigations on single crystals. The analysis of the SQUID magnetic susceptibility data for 4 a gave intramolecular ferromagnetic couplings of the cobalt(II) ions (J(1) approximately 20.4 K, J(2) approximately 7.6 K), resulting in an S=6 ground-state multiplet. The anisotropy was found to be of the easy-axis type (D=-1.55 K) with a resulting anisotropy barrier of Delta approximately 55.8 K. Two-dimensional electron-gas (2DEG) Hall magnetization measurements revealed that complex 4 a is a single-molecule magnet and shows hysteretic magnetization characteristics with typical temperature and sweep-rate dependencies below a blocking temperature of about 4.4 K. The hysteresis loops collapse at zero field owing to fast quantum tunneling of the magnetization (QTM). The structural and electronic properties of cobalt(II) cubane 4 a, deposited on a highly oriented pyrolytic graphite (HOPG) surface, were investigated by means of STM and current imaging tunneling spectroscopy (CITS) at RT and standard atmospheric pressure. In CITS measurements the rather large contrast found at the expected locations of the metal centers of the molecules indicated the presence of a strongly localized LUMO.

  15. Synthesis and DNA cleavage activities of mononuclear macrocyclic polyamine zinc(II), copper(II), cobalt(II) complexes which linked with uracil.

    PubMed

    Wang, Xiao-Yan; Zhang, Ji; Li, Kun; Jiang, Ning; Chen, Shan-Yong; Lin, Hong-Hui; Huang, Yu; Ma, Li-Jian; Yu, Xiao-Qi

    2006-10-01

    Mononuclear macrocyclic polyamine zinc(II), copper(II), cobalt(II) complexes, which could attach to peptide nucleic acid (PNA), were synthesized as DNA cleavage agents. The structures of these new mononuclear complexes were identified by MS and (1)H NMR spectroscopy. The catalytic activities on DNA cleavage of these mononuclear complexes with different central metals were subsequently studied, which showed that copper complex was better catalyst in the DNA cleavage process than zinc and cobalt complexes. The effects of reaction time, concentration of complexes were also investigated. The results indicated that the copper(II) complexes could catalyze the cleavage of supercoiled DNA (pUC 19 plasmid DNA) (Form I) under physiological conditions to produce selectively nicked DNA (Form II, no Form III produced) with high yields. The mechanism of the cleavage process was also studied.

  16. Neutral (bis-beta-diketonato) iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) metallocycles: structural, electrochemical and solvent extraction studies.

    PubMed

    Clegg, Jack K; Bray, David J; Gloe, Kerstin; Gloe, Karsten; Hayter, Michael J; Jolliffe, Katrina A; Lawrance, Geoffrey A; Meehan, George V; McMurtrie, John C; Lindoy, Leonard F; Wenzel, Marco

    2007-05-07

    Neutral dimeric metallocyclic complexes of type [M(2)(L(1))(2)B(n)] (where M = cobalt(II), nickel(II) and zinc(II), L(1) is the doubly deprotonated form of a 1,3-aryl linked bis-beta-diketone ligand of type 1,3-bis(RC(O)CH(2)C(O))C(6)H(4) (R=Me, n-Pr, t-Bu) and B is pyridine (Py) or 4-ethylpyridine (EtPy)) have been synthesised, adding to similar complexes already reported for copper(II). New lipophilic ligand derivatives with R = octyl or nonyl were also prepared for use in solvent extraction experiments. Structural, electrochemical and solvent extraction investigations of selected metal complex systems from the above series are reported, with the X-ray structures of [Co(2)(L(1))(2)(Py)(4)] x 2.25CHCl(3) x 0.5H(2)O (R=Pr), [Co(2)(L(1))(2)(EtPy)(4)] (R=t-Bu), [Ni(2)(L(1))(2)(EtPy)(4)] (R=t-Bu), [Zn(2)(L(1))(2)(EtPy)(2)] (R=Me) and [Zn(2)(L(1))(2)(EtPy)(4)] (R=t-Bu) being presented. The electrochemistry of H(2)L(1) (R=t-Bu) and of [Fe(2)(L(1))(3)], [Co(2)(L(1))(2)(Py)(4)], [Ni(2)(L(1))(2)(Py)(4)], [Cu(2)(L(1))(2)] and [Zn(2)(L(1))(2)(Py)(2)] has been examined. Oxidative processes for the complexes are dominantly irreversible, but several examples of quasireversible behaviour were observed and support the assignment of an anodic process, seen between +1.0 and +1.6 V, as a metal-centred oxidation. The reduction processes for the respective metal complexes are not simple, and irreversible in most cases. Solvent extraction studies (water/chloroform) involving variable concentrations of metal, bis-beta-diketone and heterocyclic base have been performed for cobalt(II) and zinc(II) using a radiotracer technique to probe the stoichiometries of the extracted species in each case. Synergism was observed when 4-ethylpyridine was added to the bis-beta-diketone ligand in the chloroform phase. Competitive extraction studies show a clear uptake preference for copper(II) over cobalt(II), nickel(II), zinc(II) and cadmium(II).

  17. Crystal structures of salicylideneguanylhydrazinium chloride and its copper(II) and cobalt(III) chloride complexes

    SciTech Connect

    Chumakov, Yu. M. Tsapkov, V. I.; Bocelli, G.; Antosyak, B. Ya.; Shova, S. G.; Gulea, A. P.

    2006-01-15

    The crystal structures of salicylideneguanylhydrazinium chloride hydrate hemiethanol solvate (I), salicylideneguanylhydrazinium trichloroaquacuprate(II) (II), and bis(salicylideneguanylhydrazino)cobalt(III) chloride trihydrate (III) are determined using X-ray diffraction. The structures of compounds I, II, and III are solved by direct methods and refined using the least-squares procedure in the anisotropic approximation for the non-hydrogen atoms to the final factors R = 0.0597, 0.0212, and 0.0283, respectively. In the structure of compound I, the monoprotonated molecules and chlorine ions linked by hydrogen bonds form layers aligned parallel to the (010) plane. In the structure of compound II, the salicylaldehyde guanylhydrazone cations and polymer chains consisting of trichloroaquacuprate(II) anions are joined by an extended three-dimensional network of hydrogen bonds. In the structure of compound III, the [Co(LH){sub 2}]{sup +} cations, chloride ions, and molecules of crystallization water are linked together by a similar network.

  18. Synthesis, Crystal Structure, and Thermal Decomposition of the Cobalt(II) Complex with 2-Picolinic Acid

    PubMed Central

    Li, Di

    2014-01-01

    The cobalt(II) complex of 2-picolinic acid (Hpic), namely, [Co(pic)2(H2O)2] · 2H2O, was synthesized with the reaction of cobalt acetate and 2-picolinic acid as the reactants by solid-solid reaction at room temperature. The composition and structure of the complex were characterized by elemental analysis, infrared spectroscopy, single crystal X-ray diffraction, and thermogravimetry-differential scanning calorimetry (TG-DSC). The crystal structure of the complex belongs to monoclinic system and space group P2(1)/n, with cell parameters of a = 9.8468(7) Å, b = 5.2013(4) Å, c = 14.6041(15) Å, β = 111.745(6)°, V = 747.96(11) Å3, Z = 2, Dc = 1.666 g cm−3, R1 = 0.0297, and wR2 = 0.0831. In the title complex, the Co(II) ion is six-coordinated by two pyridine N atoms and two carboxyl O atoms from two 2-picolinic acid anions, and two O atoms from two H2O molecules, and forming a slightly distorted octahedral geometry. The thermal decomposition processes of the complex under nitrogen include dehydration and pyrolysis of the ligand, and the final residue is cobalt oxalate at about 450°C. PMID:24578654

  19. Diaqua-bis-(hydrogen tartrato)cobalt(II) dihydrate.

    PubMed

    Du, Chao-Jun; Zhang, Qun-An; Wang, Li-Sheng; Du, Chao-Ling

    2012-02-01

    The title complex, [Co(C(4)H(5)O(6))(2)(H(2)O)(2)]·2H(2)O, contains a Co(II) ion, two single deprotonated tartrate anions, two coordinated water mol-ecules and two lattice water mol-ecules. The coordination geometry of the Co(II) ion is a distorted octa-hedron with two O atoms from two coordinated water mol-ecules occupying cis positions in the equatorial plane and four O atoms from two hydrogen tartrate ions occupying the remaining positions. In the crystal, inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

  20. Selective, Tunable O2 Binding in Cobalt(II)-Triazolate/Pyrazolate Metal-Organic Frameworks.

    PubMed

    Xiao, Dianne J; Gonzalez, Miguel I; Darago, Lucy E; Vogiatzis, Konstantinos D; Haldoupis, Emmanuel; Gagliardi, Laura; Long, Jeffrey R

    2016-06-08

    The air-free reaction of CoCl2 with 1,3,5-tri(1H-1,2,3-triazol-5-yl)benzene (H3BTTri) in N,N-dimethylformamide (DMF) and methanol leads to the formation of Co-BTTri (Co3[(Co4Cl)3(BTTri)8]2·DMF), a sodalite-type metal-organic framework. Desolvation of this material generates coordinatively unsaturated low-spin cobalt(II) centers that exhibit a strong preference for binding O2 over N2, with isosteric heats of adsorption (Qst) of -34(1) and -12(1) kJ/mol, respectively. The low-spin (S = 1/2) electronic configuration of the metal centers in the desolvated framework is supported by structural, magnetic susceptibility, and computational studies. A single-crystal X-ray structure determination reveals that O2 binds end-on to each framework cobalt center in a 1:1 ratio with a Co-O2 bond distance of 1.973(6) Å. Replacement of one of the triazolate linkers with a more electron-donating pyrazolate group leads to the isostructural framework Co-BDTriP (Co3[(Co4Cl)3(BDTriP)8]2·DMF; H3BDTriP = 5,5'-(5-(1H-pyrazol-4-yl)-1,3-phenylene)bis(1H-1,2,3-triazole)), which demonstrates markedly higher yet still fully reversible O2 affinities (Qst = -47(1) kJ/mol at low loadings). Electronic structure calculations suggest that the O2 adducts in Co-BTTri are best described as cobalt(II)-dioxygen species with partial electron transfer, while the stronger binding sites in Co-BDTriP form cobalt(III)-superoxo moieties. The stability, selectivity, and high O2 adsorption capacity of these materials render them promising new adsorbents for air separation processes.

  1. Dinuclear cobalt(II) and copper(II) complexes with a Py2N4S2 macrocyclic ligand.

    PubMed

    Núñez, Cristina; Bastida, Rufina; Lezama, Luis; Macías, Alejandro; Pérez-Lourido, Paulo; Valencia, Laura

    2011-06-20

    The interaction between Co(II) and Cu(II) ions with a Py(2)N(4)S(2)-coordinating octadentate macrocyclic ligand (L) to afford dinuclear compounds has been investigated. The complexes were characterized by microanalysis, conductivity measurements, IR spectroscopy and liquid secondary ion mass spectrometry. The crystal structure of the compounds [H(4)L](NO(3))(4), [Cu(2)LCl(2)](NO(3))(2) (5), [Cu(2)L(NO(3))(2)](NO(3))(2) (6), and [Cu(2)L(μ-OH)](ClO(4))(3)·H(2)O (7) was also determined by single-crystal X-ray diffraction. The [H(4)L](4+) cation crystal structure presents two different conformations, planar and step, with intermolecular face-to-face π,π-stacking interactions between the pyridinic rings. Complexes 5 and 6 show the metal ions in a slightly distorted square-pyramidal coordination geometry. In the case of complex 7, the crystal structure presents the two metal ions joined by a μ-hydroxo bridge and the Cu(II) centers in a slightly distorted square plane or a tetragonally distorted octahedral geometry, taking into account weak interactions in axial positions. Electron paramagnetic resonance spectroscopy is in accordance with the dinuclear nature of the complexes, with an octahedral environment for the cobalt(II) compounds and square-pyramidal or tetragonally elongated octahedral geometries for the copper(II) compounds. The magnetic behavior is consistent with the existence of antiferromagnetic interactions between the ions for cobalt(II) and copper(II) complexes, while for the Co(II) ones, this behavior could also be explained by spin-orbit coupling.

  2. Octahedral-tetrahedral equilibrium and solvent exchange of cobalt(II) ions in primary alkylamines.

    PubMed

    Aizawa, Sen-ichi; Funahashi, Shigenobu

    2002-08-26

    The enthalpy differences (Delta H degrees ) of the equilibrium between the octahedral and tetrahedral solvated cobalt(II) complexes were obtained in some primary alkylamines such as propylamine (pa, 36.1 +/- 2.3 kJ mol(-1)), n-hexylamine (ha, 34.9 +/- 1.0 kJ mol(-1)), 2-methoxyethylamine (meea, 44.8 +/- 3.1 kJ mol(-1)), and benzylamine (ba, 50.1 +/- 3.6 kJ mol(-1)) by the spectrophotometric method. The differences in the energy levels between the two geometries of the cobalt(II) complexes in the spherically symmetric field (Delta E(spher)) were estimated from the values of Delta H degrees by offsetting the ligand field stabilization energies. It was indicated that the value of Delta E(spher) is the decisive factor in determining the value of Delta H degrees and is largely dependent on the electronic repulsion between the d-electrons and the donor atoms and the interelectronic repulsion in the d orbitals. The comparison between activation enthalpies (Delta H(++)) for the solvent exchange reactions of octahedral cobalt(II) ions in pa and meea revealed that the unexpectedly large rate constant and small Delta H(++) in pa are attributed to the strong electronic repulsion in the ground state and removal of the electronic repulsion in the dissociative transition state, which can give the small Delta E(spher) between the ground and transition states. Differences in the solvent exchange rates and the DeltaH(++) values of the octahedral metal(II) ions in some other solvents are discussed in connection with the electronic repulsive factors.

  3. Management of Stage II glottic cancer. [Cobalt 60

    SciTech Connect

    Jose, B.,; Mohammed, A.; Calhoun, D.L.

    1981-08-01

    A detailed retrospective analysis was done of 55 patients with Stage II (TsNqMq) glottic cancer, treated at the University of Louisville Radiation Center from October 1953 to December 1975. Ninety-one percent of the patients were male. Eight-five percent of the patients had squamous cell carcinoma. The five year adjusted survival rate was 81% with a standard error of 5%. Twenty-seven percent of the patients had local failure and 58% of them were salvaged by further surgery. The median time to recurrence was eleven months. There was no case of laryngeal necrosis, and good function of the larynx was achieved in the majority of the patients. Eight second cancers were diagnosed during the continued follow-up of these patients. A brief review of the literature is included.

  4. Solvent extraction separation of nickel and cobalt from a sulfate solution containing iron(II) and magnesium using versatic 10

    NASA Astrophysics Data System (ADS)

    Ichlas, Zela Tanlega; Purwadaria, Sunara

    2017-01-01

    The separation of nickel and cobalt from a synthetic sulfate solution that contains iron(II) and magnesium via solvent extraction techniques using a neodecanoic acid, Versatic 10, as extractant was explored. The extraction behavior of the metals was investigated by varying the operating pH while the stripping behavior was investigated by varying the acidity of the stripping agent which was sulfuric acid. The experimental results demonstrate that nickel, cobalt and iron(II) can be separated easily from magnesium via selective extraction using 20% Versatic 10 as extractant and 5% tri-n-butyl phosphate (TBP) as phase modifier at pH 7.0, while the nickel and cobalt in the loaded organic phase can be separated from iron(II) by selective stripping of the two metals using 0.1 mol/L sulfuric acid solution leaving iron(II) in the organic phase. Attempts to optimize the extraction and stripping processes were reported.

  5. Cytotoxic activity, X-ray crystal structures and spectroscopic characterization of cobalt(II), copper(II) and zinc(II) coordination compounds with 2-substituted benzimidazoles.

    PubMed

    Sánchez-Guadarrama, Obdulia; López-Sandoval, Horacio; Sánchez-Bartéz, Francisco; Gracia-Mora, Isabel; Höpfl, Herbert; Barba-Behrens, Noráh

    2009-09-01

    Herein we present the synthesis, structural and spectroscopic characterization of coordination compounds of cobalt(II), copper(II) and zinc(II) with 2-methylbenzimidazole (2mbz), 2-phenylbenzimidazole (2phbz), 2-chlorobenzimidazole (2cbz), 2-benzimidazolecarbamate (2cmbz) and 2-guanidinobenzimidazole (2gbz). Their cytotoxic activity was evaluated using human cancer cell lines, PC3 (prostate), MCF-7 (breast), HCT-15 (colon), HeLa (cervic-uterine), SKLU-1 (lung) and U373 (glioblastoma), showing that the zinc(II) and copper(II) compounds [Zn(2mbz)(2)Cl(2)].0.5H(2)O, [Zn(2cmbz)(2)Cl(2)].EtOH, [Cu(2cmbz)Br(2)].0.7H(2)O and [Cu(2gbz)Br(2)] had significant cytotoxic activity. The isostructural cobalt(II) complexes showed not significant activity. The cytotoxic activity is related to the presence of halides in the coordination sphere of the metal ion. Recuperation experiments with HeLa cells, showed that the cells recuperated after removing the copper(II) compounds and, on the contrary, the cells treated with the zinc(II) compounds did not. These results indicate that the mode of action of the coordination compounds is different.

  6. Bis[bis-(penta-methyl-cyclo-penta-dien-yl)cobalt(III)] tetra-chlorido-cobaltate(II) di-chloro-methane disolvate.

    PubMed

    Merola, Joseph S; Ngo, Mai; Karpin, George W

    2013-01-01

    The title compound, [Co(C10H15)2]2[CoCl4]·2CH2Cl2, was isolated as a dichloromethane solvate and was formed in the reaction between lithium penta-methyl-cyclo-penta-dienide and anyhydrous cobalt(II) chloride in tetra-hydro-furan. There are two deca-methyl-cobaltocenium cations, one tetrachloridocobaltate(II) anion and two di-chloro-methane solvent mol-ecules in the formula unit. There is a slight disorder of the di-chloro-methane solvent which was treated with a two-site model [occupancy rates = 0.765 (4) and 0.235 (4)]. The di-chloro-methane mol-ecules display significant C-H⋯Cl inter-actions with the tetrachloridocobaltate(II) dianion. The cobalt atom of the deca-methyl-cobaltocenium cation sits on a twofold rotation axis, with only one penta-methyl-cyclo-penta-diene ligand being unique and the second generated by symmetry. The cobalt atom of the [CoCl4](-2) ion sits on a special site with -4 symmetry, with one unique chloride ligand and the others generated by the fourfold inversion axis.

  7. Fluorescence reaction of 5-(p-methoxyphenylazo)-8-(p-tolylsulfonamido)quinoline with cobalt(II) and its analytical application

    SciTech Connect

    Zeng Zuotao ) Xu Qiheng )

    1992-08-01

    5-(p-Methoxyphenylazo)-8-(p-tolylsulfonamido)quinoline(MTAQ) has been synthesized. The product was checked by IR, thermogravimetry, NMR and elemental analysis. A highly sensitive spectrofluorimetric method has been developed for the determination of cobalt(II) based on the formation of a complex with MTAQ in slightly basic medium aqueous solution and in the presence of nonionic surfactant, tween-80. The complex shows two excitation maxima at 304 nm and 338 nm, its emission maximum is centered at 402nm. The fluorescence intensity is proportional to cobalt(II) concentration in the range of 0-85 ppb. The method has good selectivity and has been applied to the direct fluorimetric determination of trace cobalt(II) in pig's liver, Dianchi shrimp and celery.

  8. Part I. Cobalt thiolate complexes modeling the active site of cobalt nitrile hydratase. Part II. Formation of inorganic nanoparticles on protein scaffolding in Escherichia coli glutamine synthetase

    NASA Astrophysics Data System (ADS)

    Kung, Irene Yuk Man

    Part I. A series of novel cobalt dithiolate complexes with mixed imine/amine ligand systems is presented here as electronic and structural models for the active site in the bacterial enzyme class, nitrile hydratase (NHase). Pentadentate cobalt(II) complexes with S2N 3 ligand environments are first studied as precursors to the more relevant cobalt(III) complexes. Adjustment of the backbone length by removal of a methylene group increases the reactivity of the system; whereas reduction of the two backbone imine bonds to allow free rotation about those bonds may decrease reactivity. Reactivity change due to the replacement of the backbone amine proton with a more sterically challenging methyl group is not yet clear. Upon oxidation, the monocationic pentadentate cobalt(III) complex, 1b, shows promising reactivity similar to that of NHase. The metal's open coordination site allows reversible binding of the endogenous, monoanionic ligands, N 3- and NCS-. Oxygenation of the thiolate sulfur atoms by exposure to O2 and H2O 2 produces sulfenate and sulfinate ligands in complex 8, which resembles the crystal structure of "deactivated" Fe NHase. However, its lack of reactivity argues against the oxygenated enzyme structure as the active form. Six-coordinate cobalt(III) complexes with S2N4 amine/amine ligand systems are also presented as analogues of previously reported iron(III) compounds, which mimic the spectroscopic properties of Fe NHase. The cobalt complexes do not seem to similarly model Co NHase. However, the S = 0 cobalt(III) center can be spectroscopically silent and difficult to detect, making comparison with synthetic models using common techniques hard. Part II. Dodecameric Escherichia coli glutamine synthetase mutant, E165C, stacks along its six-fold axis to produce tubular nanostructures in the presence of some divalent metal ions, as does the wild type enzyme. The centrally located, engineered Cys-165 residues appear to bind to various species and may serve as

  9. Simultaneous Determination of Cobalt(II) and Nickel(II) by Fourth-Order Derivative Spectrophotometric Method Using 2-Hydroxy-3-Methoxy Benzaldehyde Thiosemicarbazone

    PubMed Central

    Kumar, A. Praveen; Reddy, P. Raveendra; Reddy, V. Krishna

    2007-01-01

    A simple and new simultaneous fourth derivative spectrophotometric method is proposed for the analysis of a two-component system containing cobalt(II) and nickel(II) without separation using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a chromophoric reagent. The reagent reacts with cobalt(II) and nickel(II) at pH 6.0, forming soluble brown and yellow colored species, respectively. Cobalt(II) and nickel(II) present in themixture are simultaneously determined without solving the simultaneous equations bymeasuring the fourth derivative amplitudes at 468.5 nm and 474.5 nm, respectively. The derivative amplitudes obey Beer's law at 468.5 nm and 474.5 nm for Co(II) and Ni(II) in the range 0.059–3.299 μg mL−1 and 0.058–3.285 μg mL−1 respectively. A large number of foreign ions do not interfere in the present method. The present simultaneous method is used for the determination of micro amounts of cobalt in biological samples, nickel in plant samples, and in some alloy steels and soil sample. PMID:17671609

  10. Correlation of reactivity with structural factors in a series of Fe(II) substituted cobalt ferrites

    SciTech Connect

    Sileo, Elsa E.; Garcia Rodenas, Luis; Paiva-Santos, Carlos O.; Stephens, Peter W.; Morando, Pedro J. . E-mail: morando@cnea.gov.ar; Blesa, Miguel A.

    2006-07-15

    A series of powdered cobalt ferrites, Co {sub x} Fe{sub 3-} {sub x} O{sub 4} with 0.66{<=}x<1.00 containing different amounts of Fe{sup II}, were synthesized by a mild procedure, and their Fe and Co site occupancies and structural characteristics were explored using X-ray anomalous scattering and the Rietveld refinement method. The dissolution kinetics, measured in 0.1 M oxalic acid aqueous solution at 70 deg. C, indicate in all cases the operation of a contracting volume rate law. The specific rates increased with the Fe{sup II} content following approximately a second-order polynomial expression. This result suggests that the transfer of Fe{sup III} controls the dissolution rate, and that the leaching of a first layer of ions Co{sup II} and Fe{sup II} leaves exposed a surface enriched in slower dissolving octahedral Fe{sup III} ions. Within this model, inner vicinal lattice Fe{sup II} accelerates the rate of Fe{sup III} transfer via internal electron hopping. A chain mechanism, involving successive electron transfers, fits the data very well. - Graphical abstract: The electron exchange between octahedral Fe{sup II} and Fe{sup III} ions has important consequences on the specific dissolution rates. Display Omitted.

  11. Selective, Tunable O2 Binding in Cobalt(II)–Triazolate/Pyrazolate Metal–Organic Frameworks

    PubMed Central

    2016-01-01

    The air-free reaction of CoCl2 with 1,3,5-tri(1H-1,2,3-triazol-5-yl)benzene (H3BTTri) in N,N-dimethylformamide (DMF) and methanol leads to the formation of Co-BTTri (Co3[(Co4Cl)3(BTTri)8]2·DMF), a sodalite-type metal–organic framework. Desolvation of this material generates coordinatively unsaturated low-spin cobalt(II) centers that exhibit a strong preference for binding O2 over N2, with isosteric heats of adsorption (Qst) of −34(1) and −12(1) kJ/mol, respectively. The low-spin (S = 1/2) electronic configuration of the metal centers in the desolvated framework is supported by structural, magnetic susceptibility, and computational studies. A single-crystal X-ray structure determination reveals that O2 binds end-on to each framework cobalt center in a 1:1 ratio with a Co–O2 bond distance of 1.973(6) Å. Replacement of one of the triazolate linkers with a more electron-donating pyrazolate group leads to the isostructural framework Co-BDTriP (Co3[(Co4Cl)3(BDTriP)8]2·DMF; H3BDTriP = 5,5′-(5-(1H-pyrazol-4-yl)-1,3-phenylene)bis(1H-1,2,3-triazole)), which demonstrates markedly higher yet still fully reversible O2 affinities (Qst = −47(1) kJ/mol at low loadings). Electronic structure calculations suggest that the O2 adducts in Co-BTTri are best described as cobalt(II)–dioxygen species with partial electron transfer, while the stronger binding sites in Co-BDTriP form cobalt(III)–superoxo moieties. The stability, selectivity, and high O2 adsorption capacity of these materials render them promising new adsorbents for air separation processes. PMID:27180991

  12. Spectrophotometric Determination of Iron(II) and Cobalt(II) by Direct, Derivative, and Simultaneous Methods Using 2-Hydroxy-1-Naphthaldehyde-p-Hydroxybenzoichydrazone.

    PubMed

    Devi, V S Anusuya; Reddy, V Krishna

    2012-01-01

    Optimized and validated spectrophotometric methods have been proposed for the determination of iron and cobalt individually and simultaneously. 2-hydroxy-1-naphthaldehyde-p-hydroxybenzoichydrazone (HNAHBH) reacts with iron(II) and cobalt(II) to form reddish-brown and yellow-coloured [Fe(II)-HNAHBH] and [Co(II)-HNAHBH] complexes, respectively. The maximum absorbance of these complexes was found at 405 nm and 425 nm, respectively. For [Fe(II)-HNAHBH], Beer's law is obeyed over the concentration range of 0.055-1.373 μg mL(-1) with a detection limit of 0.095 μg mL(-1) and molar absorptivity ɛ, 5.6 × 10(4) L mol(-1) cm(-1). [Co(II)-HNAHBH] complex obeys Beer's law in 0.118-3.534 μg mL(-1) range with a detection limit of 0.04 μg mL(-1) and molar absorptivity, ɛ of 2.3 × 10(4) L mol(-1) cm(-1). Highly sensitive and selective first-, second- and third-order derivative methods are described for the determination of iron and cobalt. A simultaneous second-order derivative spectrophotometric method is proposed for the determination of these metals. All the proposed methods are successfully employed in the analysis of various biological, water, and alloy samples for the determination of iron and cobalt content.

  13. Uptake of {sup 64}Cu-oxine by marine phytoplankton

    SciTech Connect

    Croot, P.L.; Karson, B.; Elteren, J.T. van; Kroon, J.J.

    1999-10-15

    Short-term uptake experiments using fie phytoplankton species (Synechococcus clone DC2, Amphidinium carterae, Chrysochromulina polylepis, Ditylum brightwelli, and Prorocentrum micans) demonstrated rapid uptake of the lipophilic complex {sup 64}Cu-oxine, presumably by diffusion of the complex across the plasma membrane. This passive uptake mechanism was extremely rapid and significantly faster than facilitated uptake by the free metal ion. Measured values of the observed permeability, P{sub obs}, ranged from 0.55 to 18.6 x 10{sup {minus}4} cm s{sup {minus}1}, showing only small differences between the various algal species. Removal rate constants, k{sup bio}, varied much more widely, 0.009--570 x 10{sup {minus}9} L cell{sup {minus}1} h{sup {minus} 1}, between the algae, indicating the influence of surface area on the uptake kinetics. Maximum internal Cu levels were reached after approximately 2 h, showing that a major limiting factor in the uptake of Cu from Cu-oxine is the concentration of intracellular Cu binding sites.

  14. Thermochemical study of the processes of complexation of cobalt(II) ions with L-histidine in aqueous solution

    NASA Astrophysics Data System (ADS)

    Gorboletova, G. G.; Metlin, A. A.

    2015-09-01

    Thermal effects of the complexation of cobalt(II) ions with L-histidine at 298.15 K and several values of the ionic strength against the background of KNO3 are determined by means of direct calorimetry. The standard thermodynamic characteristics of the reactions of complexation in the aqueous solution have been calculated.

  15. Synthesis and Temperature-Induced Structural Phase and Spin Transitions in Hexadecylboron-Capped Cobalt(II) Hexachloroclathrochelate and Its Diamagnetic Iron(II)-Encapsulating Analogue.

    PubMed

    Vologzhanina, Anna V; Belov, Alexander S; Novikov, Valentin V; Dolganov, Alexander V; Romanenko, Galina V; Ovcharenko, Victor I; Korlyukov, Alexander A; Buzin, Mikhail I; Voloshin, Yan Z

    2015-06-15

    Template condensation of dichloroglyoxime with n-hexadecylboronic acid on the corresponding metal ion as a matrix under vigorous reaction conditions afforded n-hexadecylboron-capped iron and cobalt(II) hexachloroclathrochelates. The complexes obtained were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV-vis, (1)H and (13)C{(1)H} NMR, (57)Fe Mössbauer spectroscopies, SQUID magnetometry, electron paramagnetic resonance, and cyclic voltammetry (CV) and by X-ray crystallography. The multitemperature single-crystal X-ray diffraction, SQUID magnetometry, and differential scanning calorimetry experiments were performed to study the temperature-induced spin-crossover [for the paramagnetic cobalt(II) complex] and the crystal-to-crystal phase transitions (for both of these clathrochelates) in the solid state. Analysis of their crystal packing using the molecular Voronoi polyhedra and the Hirshfeld surfaces reveals the structural rearrangements of the apical long-chain alkyl substituents resulting from such phase transitions being more pronounced for a macrobicyclic cobalt(II) complex. Its fine-crystalline sample undergoes the gradual and fully reversible spin transition centered at approximately 225 K. The density functional theory calculated parameters for an isolated molecule of this cobalt(II) hexachloroclathrochelate in its low- and high-spin states were found to be in excellent agreement with the experimental data and allowed to localize the spin density within a macrobicyclic framework. CV of the cobalt(II) complex in the cathodic range contains one reversible wave assigned to the Co(2+/+) redox couple with the reduced anionic cobalt(I)-containing species stabilized by the electronic effect of six strong electron-withdrawing chlorine substituents. The quasireversible character of the Fe(2+/+) wave suggests that the anionic iron(I)-containing macrobicyclic species undergo substantial structural changes and side chemical reactions after such

  16. Kinetics of Formation of Cobalt(II)- and Nickel(II) Carbonic Anhydrase.

    ERIC Educational Resources Information Center

    McQuate, Robert S.; Reardon, John E.

    1978-01-01

    Discusses the kinetic behavior associated with the interaction of metal ions with apocarbonic anhydrase, focusing on the formation of two metallocarbonic anhydrase--the biochemically active Co(II) and the inactive Ni(II)derivatives. (GA)

  17. Thermochromism, stability and thermodynamics of cobalt(II) complexes in newly synthesized nitrate based ionic liquid and its photostability.

    PubMed

    Banić, Nemanja; Vraneš, Milan; Abramović, Biljana; Csanádi, János; Gadžurić, Slobodan

    2014-11-07

    In this work a 1-(2-hydroxyethyl)-3-methylimidazolium nitrate ionic liquid, [HO(CH2)2mim]NO3, has been synthesized in order to serve as a new thermochromic material upon addition of cobalt(II) ions. Spectrophotometric measurements of a series of cobalt(II) nitrate and cobalt(II) chloride solutions in [HO(CH2)2mim]NO3 at 298.15, 308.15, 318.15, 328.15, and 338.15 K, were performed. Based on the recorded spectra, the overall stability constants and thermodynamic parameters for the cobalt(II) associations with chloride and nitrate ions were calculated. The thermodynamic calculations suggest that thermochromism is not observed in the ionic medium due to a small entropy change during the replacement of nitrate with chloride ions in the co-ordination sphere of cobalt(II). The absence of the molecular solvent was also the reason for the lack of thermochromism. Thus, cobalt(II) solutions in [HO(CH2)2mim]NO3 and water mixtures were studied as a new and green medium that can be used for the auto-regulation of the light intensity and shade protection. The investigated system with water upon addition of cobalt(II) was found to be a far more efficient and responsive thermochromic medium for all of the studied systems up until now. The structure of [HO(CH2)2mim]NO3 was confirmed by both (1)H NMR and IR spectroscopy. Also, the efficiency of different advanced oxidation processes (UV-induced photolysis, UV/H2O2 photolysis, heterogeneous photocatalysis using TiO2 Degussa P25 and TiO2 with 7.24%, w/w Fe catalysts) for [HO(CH2)2mim]NO3 degradation were investigated. The reaction intermediates formed during the photo-oxidation process were identified using LC-ESI-MS/MS and (1)H NMR techniques.

  18. Inhibitory effect of water on the oxygen reduction catalyzed by cobalt(II) tetraphenylporphyrin.

    PubMed

    Trojánek, Antonín; Langmaier, Jan; Kvapilová, Hana; Záliš, Stanislav; Samec, Zdeněk

    2014-03-20

    Stopped-flow kinetic measurements, UV-vis spectroscopy, rotating disk voltammetry, and quantum chemical calculations are used to clarify the role of water in the homogeneous two-electron reduction of O2 to H2O2 in 1,2-dichloroethane (DCE) using ferrocene (Fc) as an electron donor, tetrakis(pentafluorophenyl)boric acid (HTB) as a proton donor, and [5,10,15,20-tetraphenyl-21H,23H-porphine]cobalt(II) (Co(II)TTP) as a catalyst. Kinetic analysis suggests that the reaction is controlled by the intramolecular proton coupled electron transfer to the O2 molecule coordinated to the metal center producing the O2H(•) radical. This rate-determining step is common to both the O2 reduction by Fc catalyzed by Co(II)TPP and the O2 reduction by Co(II)TPP itself. Experimental data point to the competitive coordination of water to the metal center leading to a strong inhibition of the catalytic reaction. In agreement with this finding, quantum chemical calculations indicate that water is bound to the metal center much more strongly than triplet O2. A similar effect is demonstrated also for the O2 reduction catalyzed by the porphyrin free base (H2TPP), though its rate is lower by 2 orders of magnitude.

  19. A Bioinspired Molecular Polyoxometalate Catalyst with Two Cobalt(II) Oxide Cores for Photocatalytic Water Oxidation.

    PubMed

    Wei, Jie; Feng, Yingying; Zhou, Panpan; Liu, Yan; Xu, Jingyin; Xiang, Rui; Ding, Yong; Zhao, Chongchao; Fan, Linyuan; Hu, Changwen

    2015-08-24

    To overcome the bottleneck of water splitting, the exploration of efficient, selective, and stable water oxidation catalysts (WOCs) is crucial. We report an all-inorganic, oxidatively and hydrolytically stable WOC based on a polyoxometalate [(A-α-SiW9 O34)2Co8(OH)6(H2O)2(CO3)3](16-) (Co8 POM). As a cobalt(II)-based cubane water oxidation catalyst, Co8POM embeds double Co(II)4O3 cores. The self-assembled catalyst is similar to the oxygen evolving complex (OEC) of photosystem II (PS II). Using [Ru(bpy)3](2+) as a photosensitizer and persulfate as a sacrificial electron acceptor, Co8POM exhibits excellent water oxidation activity with a turnover number (TON) of 1436, currently the highest among bioinspired catalysts with a cubical core, and a high initial turnover frequency (TOF). Investigation by several spectroscopy, spectrometry, and other techniques confirm that Co8POM is a stable and efficient catalyst for visible light-driven water oxidation. The results offer a useful insight into the design of water oxidation catalysts.

  20. Coordination conversion of cobalt(II) in binary aqueous-organic solvents

    SciTech Connect

    Khvostova, N.O.; Karapetyan, G.O.; Yanush, O.V.

    1985-11-01

    It has been shown that the thermochromic conversions of cobalt(II) in binary solvents are influenced by a number of factors: the nature of the solvent, the strength of the complexes of octahedral symmetry formed, the outer-sphere influence of the solvent on the complexes, the form of the anion, the solvation of the participants in the reaction, and the interaction of the components of the solvent with one another. A correlation between the strength and the spectral position of the absorption bands of the complexes of the activator has been established, and a spectroscopic criterion for selecting the solvents has been proposed. The expediency of using binary solvents to create effective thermochromic media with variable phototransmission has been substantiated.

  1. Engineering surface atomic structure of single-crystal cobalt (II) oxide nanorods for superior electrocatalysis

    PubMed Central

    Ling, Tao; Yan, Dong-Yang; Jiao, Yan; Wang, Hui; Zheng, Yao; Zheng, Xueli; Mao, Jing; Du, Xi-Wen; Hu, Zhenpeng; Jaroniec, Mietek; Qiao, Shi-Zhang

    2016-01-01

    Engineering the surface structure at the atomic level can be used to precisely and effectively manipulate the reactivity and durability of catalysts. Here we report tuning of the atomic structure of one-dimensional single-crystal cobalt (II) oxide (CoO) nanorods by creating oxygen vacancies on pyramidal nanofacets. These CoO nanorods exhibit superior catalytic activity and durability towards oxygen reduction/evolution reactions. The combined experimental studies, microscopic and spectroscopic characterization, and density functional theory calculations reveal that the origins of the electrochemical activity of single-crystal CoO nanorods are in the oxygen vacancies that can be readily created on the oxygen-terminated {111} nanofacets, which favourably affect the electronic structure of CoO, assuring a rapid charge transfer and optimal adsorption energies for intermediates of oxygen reduction/evolution reactions. These results show that the surface atomic structure engineering is important for the fabrication of efficient and durable electrocatalysts. PMID:27650485

  2. Engineering surface atomic structure of single-crystal cobalt (II) oxide nanorods for superior electrocatalysis.

    PubMed

    Ling, Tao; Yan, Dong-Yang; Jiao, Yan; Wang, Hui; Zheng, Yao; Zheng, Xueli; Mao, Jing; Du, Xi-Wen; Hu, Zhenpeng; Jaroniec, Mietek; Qiao, Shi-Zhang

    2016-09-21

    Engineering the surface structure at the atomic level can be used to precisely and effectively manipulate the reactivity and durability of catalysts. Here we report tuning of the atomic structure of one-dimensional single-crystal cobalt (II) oxide (CoO) nanorods by creating oxygen vacancies on pyramidal nanofacets. These CoO nanorods exhibit superior catalytic activity and durability towards oxygen reduction/evolution reactions. The combined experimental studies, microscopic and spectroscopic characterization, and density functional theory calculations reveal that the origins of the electrochemical activity of single-crystal CoO nanorods are in the oxygen vacancies that can be readily created on the oxygen-terminated {111} nanofacets, which favourably affect the electronic structure of CoO, assuring a rapid charge transfer and optimal adsorption energies for intermediates of oxygen reduction/evolution reactions. These results show that the surface atomic structure engineering is important for the fabrication of efficient and durable electrocatalysts.

  3. Cytotoxic copper(II), cobalt(II), zinc(II), and nickel(II) coordination compounds of clotrimazole.

    PubMed

    Betanzos-Lara, Soledad; Gómez-Ruiz, Celedonio; Barrón-Sosa, Lidia R; Gracia-Mora, Isabel; Flores-Álamo, Marcos; Barba-Behrens, Noráh

    2012-09-01

    Sixteen novel mononuclear Cu(II), Co(II), Zn(II), and Ni(II) complexes of the biologically active ligand clotrimazole (clotri) of the forms [M(clotri)(2)Cl(2)]·nH(2)O (1-4), [M(clotri)(2)Br(2)]·nH(2)O (5-7), [M(clotri)(3)Br(2)] (8), [M(clotri)(3)NO(3)]NO(3)·nH(2)O (9, 11), [M(clotri)(3)(NO(3))(2)]·nH(2)O (10), and [M(clotri)(3)(OH(2))(2)NO(3)]NO(3)·nH(2)O (12) were synthesized and fully characterized. Dinuclear [Cu(2)(clotri)(4)μ(2)-Cl(4)]·2H(2)O (1a) and [Cu(2)(clotri)(4)μ(2)-Br(2)]·2H(2)O (5b) as well as tetranuclear [Cu(4)(clotri)(4)μ(4)-Br(6)μ(4)-O] (5a) complexes were also isolated. Complexes 1-7, 9, and 11 present a tetrahedral geometry; complex 8 exhibits a pentacoordinated structure; complexes 1a, 10 and 12 an octahedral geometry. X-ray crystal structures of [Cu(clotri)(2)Cl(2)](1), [Cu(clotri)(2)(EtOH)Cl(2)](1·EtOH), [Zn(clotri)(2)Cl(2)] (3), [Zn(clotri)(2)Br(2)] (7), and [Cu(4)(clotri)(4)μ(4)-Br(6)μ(4)-O] (5a) were obtained. Complexes 1-12 were tested for cytotoxic activity against the human carcinoma cell lines HeLa (cervix-uterine), PC3 (prostate), and HCT-15 (colon) displaying IC(50) values <30 μM. Confocal microscopy and nuclear dying (DAPI) for complex 1 showed condensation of cromatin and nuclear membrane fragmentation. Immunocytochemical detection/expression of biomarkers suggests that complexes 1 and 9 induce cell death via apoptosis. TUNEL assay detected DNA fragmentation in HeLa cells, resulting from apoptotic signaling cascades induced by Cu(II) complexes 1 and 9. (1)H NMR studies of the Zn(II) complexes showed that they can bind to nucleotides.

  4. Single-ion magnet behaviour in mononuclear and two-dimensional dicyanamide-containing cobalt(ii) complexes.

    PubMed

    Switlicka-Olszewska, Anna; Palion-Gazda, Joanna; Klemens, Tomasz; Machura, Barbara; Vallejo, Julia; Cano, Joan; Lloret, Francesc; Julve, Miguel

    2016-06-21

    Three cobalt(ii) complexes of formulae [Co(dca)2(bim)4] (), [Co(dca)2(bim)2]n () and [Co(dca)2(bmim)2]n () [dca = dicyanamide, bim = 1-benzylimidazole and bmim = 1-benzyl-2-methylimidazole] were prepared and structurally analyzed by single-crystal X-ray crystallography. Compound is a mononuclear species where the cobalt(ii) ion is six-coordinate with four bim molecules in the equatorial positions [Co-Nbim = 2.1546(15) and 2.1489(15) Å] and two trans-positioned dca ligands [Co-Ndca = 2.1575(18) Å] in the axial sites of a somewhat distorted octahedral surrounding. The structures of and consist of two-dimensional grids of cobalt(ii) ions where each metal atom is linked to the other four metal centres by single dca bridges exhibiting the μ1,5-dca coordination mode [Co-Ndca = 2.190(3)-2.220(3) () and 2.127(3)-2.153(3) Å ()]. Two trans-coordinated bim ()/bmim () molecules achieve the six-coordination around each cobalt(ii) ion [Co-Nbim = 2.128(3)-2.134(4) Å () and Co-Nbmim = 2.156(3)-2.163(39) Å ()]. The values of the cobalt-cobalt separation through the single dca bridges are 8.927(2) and 8.968(2) Å in and 8.7110(5) and 8.7158(5) Å in . Magnetic susceptibility measurements for in the temperature range of 2.0-300 K reveal that these compounds behave as magnetically isolated high-spin cobalt(ii) ions with a significant orbital contribution to the magnetic moment. Alternating current (ac) magnetic susceptibility measurements for show a frequency dependence of out-of-phase susceptibility under static applied fields in the range of 500-2500 G, a feature which is characteristic of the single-ion magnet behaviour (SIM) of the Co(ii) ion in them. The values of the energy barrier for the magnetic relaxation (Ea) are 5.45-7.74 (), 4.53-9.24 () and 11.48-15.44 cm(-1) (). They compare well with those previously reported for the analogous dca-bridged 2D compound [Co(dca)2(atz)2]n () (Ea = 5.1 cm(-1) under an applied static field of 1000 G), which was the subject of a

  5. Adsorptive separation of rhodium(III) using Fe(III)-templated oxine type of chemically modified chitosan

    SciTech Connect

    Alam, M.S.; Inoue, Katsutoshi; Yoshizuka, Kazuharu; Ishibashi, Hideaki

    1998-03-01

    The oxine type of chemically modified chitosan was prepared by the template crosslinking method using Fe(III) as a template ion. Batchwise adsorption of rhodium(III) on this chemically modified chitosan was examined from chloride media in the absence and presence of a large amount of tin(II). It was observed that the Fe(III)-templated oxine type of chemically modified chitosan shows better performance for rhodium adsorption than that of the original chitosan. When Sn(II) is absent from the solution, Rh(III) is hardly adsorbed on the modified chitosan and the order of selectivity of the adsorption of Rh(III), Pt(IV), and Cu(II) was found to be Pt(IV) > Cu(II) {approx} Rh(III). On the other hand, adsorption of rhodium is significantly increased in the presence of Sn(II) and the selectivity order of the adsorption was drastically changed to Rh(III) > Pt(IV) {much_gt} Cu(II), which ensures selective separation of Rh(III) from their mixture. Adsorption of Rh(III) increases with an increase in the concentration of Sn(II) in the aqueous solution, and maximum adsorption is achieved at a molar ratio, [Sn]/[Rh], of >6. The adsorption of Rh(III) decreases at a high concentration of hydrochloric acid. The maximum adsorption capacity was evaluated to be 0.92 mol/kg-dry adsorbent. Stripping tests of rhodium from the loaded chemically modified chitosan were carried out using different kinds of stripping agents containing some oxidizing agent. The maximum stripping of rhodium under these experimental conditions was found to be 72.5% by a single contact with 0.5 M HCl + 8 M HNO{sub 3}.

  6. Crystal and molecular structures of trichloro-cobalt(II) complexes of epiquinine, epiquinidine, and epidihydrocinchonine.

    PubMed

    Tesarowicz, Iwona; Oleksyn, Barbara J; Nitek, Wojciech

    2007-02-01

    Cinchona alkaloids are very well known antimalarials but the mechanism of their biological action still remains to be elucidated. The structural studies of active erythro and inactive threo alkaloid complexes are an important step to this aim. In this paper results of crystal structure analysis of three cobalt complexes of threo alkaloids are presented: (epiquininium)trichlorocobalt(II) (EpiQnCoCl3), (epiquinidinium)trichlorocobalt(II) (EpiQdCoCl3) and (epidihydrocinchoninium)trichlorocobalt(II) (EpiCnCoCl3). The complexes are zwitterions in which trichlorocobalt substituents are coordinated to quinoline nitrogen atoms and quinuclidine nitrogen atoms are protonated. EpiQnCoCl3 adopts uncommon conformation with quinoline moiety oriented in the opposite direction in comparison to the analogous uncomplexed alkaloid. The packing in the crystal structures is determined mainly by the hydrogen bonds, in which the chlorine atoms of substituents and solvent molecules contribute. Atoms participating in hydrogen bonds in EpiQnCoCl3 and EpiQdCoCl3 form large rings, while in EpiCnCoCl3 only chains are present. Solvent molecules are very important for the packing mode. In contrast to most erythro alkaloids, the hydroxyl oxygen atom in the title complexes forms weak or not well defined hydrogen bonds. The contribution of very weak intramolecular interactions N1--H1...O12 cannot be excluded. Such "trace" interactions can be considered a relic of the unprotonated status of an epi alkaloid.

  7. Octanuclear zinc(II) and cobalt(II) clusters produced by cooperative tetrameric assembling of oxime chelate ligands.

    PubMed

    Akine, Shigehisa; Dong, Wenkui; Nabeshima, Tatsuya

    2006-06-12

    We have synthesized an octanuclear zinc(II) cluster [L4Zn8(H2O)3] by the complexation of 3-hydroxysalamo (H4L) with zinc(II) acetate. The complex crystallizes in the triclinic system, space group P, with unit cell parameters a = 18.233(10) A, b = 20.518(11) A, c = 21.366(11) A, alpha = 98.7557(2) degrees, beta = 99.191(11) degrees, gamma = 108.309(10) degrees, and Z = 4. The crystallographic analysis revealed the S4 symmetrical assembling of four ligands and that the tetrameric complex has three water molecules in an unsymmetrical fashion. Spectroscopic analysis of the complex strongly suggests that the octanuclear cluster also exists in solution and maintains a conformation similar to that in the crystal structure, although exchange of the coordinating water molecules presumably takes place. In addition, the formation process of the octanuclear complex is highly cooperative. A high coordinating ability of the [(salamo)Zn] unit as well as the catecholato2- moieties probably stabilizes the octanuclear assembly and makes the complexation process cooperative. The corresponding octanuclear cobalt(II) cluster [L4Co8(EtOH)3] was prepared in a similar manner. Complex [L4Co8(H2O)2X] (X = H2O or EtOH) was obtained by the recrystallization from chloroform/hexane. The complex crystallizes in the triclinic system, space group P, with unit cell parameters a = 15.2359(10) A, b = 16.9625(12) A, c = 18.9325(13) A, alpha = 101.9710(10) degrees, beta = 105.5410(10) degrees, gamma = 97.1290(10) degrees, and Z = 2. Temperature dependence of magnetic susceptibility showed a continuous decrease in the chi(M)T value with decreasing temperature, suggesting antiferromagnetic interaction among cobalt(II) ions. The magnetic susceptibility above 40 K obeys the Curie-Weiss law with a Weiss constant theta of -39 K and a Curie constant C of 19.7 cm(3) K mol(-1).

  8. Cobalt(II) sheet-like systems based on diacetic ligands: from subtle structural variances to different magnetic behaviors.

    PubMed

    Fabelo, Oscar; Pasán, Jorge; Cañadillas-Delgado, Laura; Delgado, Fernando S; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

    2009-07-06

    The preparation, X-ray crystallography, and magnetic investigation of the compounds [Co(H(2)O)(2)(phda)](n) (1), [Co(phda)](n) (2), and [Co(chda)](n) (3) [H(2)phda = 1,4-phenylenediacetic acid and H(2)chda = 1,1-cyclohexanediacetic acid] are described herein. The cobalt atoms in this series are six- (1) and four-coordinated (2 and 3) in distorted octahedral (CoO(6)) and tetrahedral (CoO(4)) environments. The structures of 1-3 consists of rectangular-grids which are built up by sheets of cobalt atoms linked through anti-syn carboxylate bridges, giving rise to either a three-dimensional structure across the phenyl ring (1 and 2) or to regularly stacked layers with the cyclohexyl groups acting as organic separators (3). The magnetic properties of 1-3 were investigated as a function of the temperature and the magnetic field. Ferromagnetic coupling between the six-coordinate cobalt(II) ions across the anti-syn carboxylate bridge occurs in 1 (J = +1.2 cm(-1)) whereas antiferromagnetic coupling among the tetrahedral cobalt(II) centers within the sheets is observed in 2 and 3 [J = -1.63 (2) and -1.70 cm(-1) (3)] together with a spin-canted structure in 3 giving rise a long-range magnetic ordering (T(c) = 7.5 K).

  9. Synthesis and oxidation catalysis of [tris(oxazolinyl)borato]cobalt(II) scorpionates

    DOE PAGES

    Reinig, Regina R.; Mukherjee, Debabrata; Weinstein, Zachary B.; ...

    2016-04-28

    The reaction of CoCl2·THF and thallium tris(4,4-dimethyl-2-oxazolinyl)phenylborate (TlToM) in tetrahydrofuran (THF) provides ToMCoCl (1) in 95 % yield; however, appropriate solvents and starting materials are required to favor 1 over two other readily formed side-products, (ToM)2Co (2) and {HToM}CoCl2 (3). ESR, NMR, FTIR, and UV/Vis spectroscopies were used to distinguish these cobalt(II) products and probe their electronic and structural properties. Even after the structures indicated by these methods were confirmed by X-ray crystallography, the spectroscopic identification of trace contaminants in the material was challenging. The recognition of possible contaminants in the synthesis of ToMCoCl in combination with the paramagnetic naturemore » of these complexes provided impetus for the utilization of X-ray powder diffraction to measure the purity of the ToMCoCl bulk sample. Furthermore, the X-ray powder diffraction results provide support for the bulk-phase purity of ToMCoCl in preparations that avoid 2 and 3. Thus, 1 is a precursor for new [tris(oxazolinyl)borato]cobalt chemistry, as exemplified by its reactions with KOtBu and NaOAc to give ToMCoOtBu (4) and ToMCoOAc (5), respectively. Compound 5 is a catalyst for the oxidation of cyclohexane with meta-chloroperoxybenzoic acid (mCPBA), and the rate constants and selectivity for cyclohexanol versus cyclohexanone and ϵ-caprolactone were assessed.« less

  10. Synthesis and oxidation catalysis of [tris(oxazolinyl)borato]cobalt(II) scorpionates

    SciTech Connect

    Reinig, Regina R.; Mukherjee, Debabrata; Weinstein, Zachary B.; Xie, Weiwei; Albright, Toshia; Baird, Benjamin; Gray, Tristan S.; Ellern, Arkady; Miller, Gordon J.; Winter, Arthur H.; Bud'ko, Sergey L.; Sadow, Aaron D.

    2016-04-28

    The reaction of CoCl2·THF and thallium tris(4,4-dimethyl-2-oxazolinyl)phenylborate (TlToM) in tetrahydrofuran (THF) provides ToMCoCl (1) in 95 % yield; however, appropriate solvents and starting materials are required to favor 1 over two other readily formed side-products, (ToM)2Co (2) and {HToM}CoCl2 (3). ESR, NMR, FTIR, and UV/Vis spectroscopies were used to distinguish these cobalt(II) products and probe their electronic and structural properties. Even after the structures indicated by these methods were confirmed by X-ray crystallography, the spectroscopic identification of trace contaminants in the material was challenging. The recognition of possible contaminants in the synthesis of ToMCoCl in combination with the paramagnetic nature of these complexes provided impetus for the utilization of X-ray powder diffraction to measure the purity of the ToMCoCl bulk sample. Furthermore, the X-ray powder diffraction results provide support for the bulk-phase purity of ToMCoCl in preparations that avoid 2 and 3. Thus, 1 is a precursor for new [tris(oxazolinyl)borato]cobalt chemistry, as exemplified by its reactions with KOtBu and NaOAc to give ToMCoOtBu (4) and ToMCoOAc (5), respectively. Compound 5 is a catalyst for the oxidation of cyclohexane with meta-chloroperoxybenzoic acid (mCPBA), and the rate constants and selectivity for cyclohexanol versus cyclohexanone and ϵ-caprolactone were assessed.

  11. Cobalt(II) β-ketoaminato complexes as novel inhibitors of neuroinflammation.

    PubMed

    Madeira, Jocelyn M; Beloukhina, Natalia; Boudreau, Kalun; Boettcher, Tyson A; Gurley, Lydia; Walker, Douglas G; McNeil, W Stephen; Klegeris, Andis

    2012-02-15

    Neuroinflammation contributes to the pathogenesis of neurological disorders including stroke, head trauma, multiple sclerosis, amyotrophic lateral sclerosis as well as age-associated neurodegenerative disorders including Alzheimer's and Parkinson's diseases. Therefore, anti-inflammatory drugs could be used to slow the progression of these diseases. We studied the anti-neuroinflammatory activity of four novel square planar cobalt(II) compounds bearing tetradentate β-ketoaminato ligands with variation in the number of CF(3) ligand substituents, as well as their corresponding unmetallated organic ligands. Cobalt (Co) complexes were consistently more active than their corresponding ligands. One of the complexes, L(3)Co at concentrations (1-10 μM) that were not toxic to cells, significantly reduced cytotoxic secretions by human monocytic THP-1 cells, astrocytoma U-373 MG cells, and primary human microglia. This anti-neurotoxic action of L(3)Co was reduced by SP600125 and PD98059, selective inhibitors of c-Jun NH2-terminal kinase (JNK) and extracellular signal regulated kinase (ERK) kinase (MEK)1/2 respectively. L(3)Co had no effect on secretion of monocyte chemotactic protein-1 (MCP-1) by THP-1 cells, but it inhibited the NADPH oxidase-dependent respiratory burst activity of differentiated human HL-60 cells. L(3)Co upregulated heme oxygenase-1 (HOX-1) expression by THP-1 cells, which may be one of the molecular mechanisms responsible for its anti-inflammatory properties. Two of the Co compounds tested showed activity only at high concentrations (50 μM), but L(2)Co was highly toxic to all cell types used. Select Co complexes, such as L(3)Co, may exhibit pharmacological properties beneficial in human diseases involving neuroinflammatory processes. Further studies of the in vivo efficacy, safety and pharmacokinetics of L(3)Co are warranted.

  12. 31-day study of cobalt(II) chloride ingestion in humans: pharmacokinetics and clinical effects.

    PubMed

    Finley, Brent L; Unice, Kenneth M; Kerger, Brent D; Otani, Joanne M; Paustenbach, Dennis J; Galbraith, David A; Tvermoes, Brooke E

    2013-01-01

    The United Kingdom Expert Group on Vitamins and Minerals concluded that ingesting cobalt (Co)-containing supplements up to 1400 μg Co/d is unlikely to produce adverse health effects. However, the associated blood Co concentrations and safety of Co-containing dietary supplements have not been fully characterized. Thus, blood Co kinetics and a toxicological assessment of hematological and biochemical parameters were evaluated following Co dietary supplementation in 5 male and 5 female volunteers who ingested approximately 1000 μg Co/d (10-19 μg Co/kg-d) as cobalt(II) chloride for a period of 31 d. Supplement intake was not associated with significant overt adverse events, alterations in clinical chemistries including blood counts and indicators of thyroid, cardiac, liver, or kidney functions, or metal sensitization. A non-clinically significant (<5%) increase in hemoglobin, hematocrit, and red blood cell (RBC) counts were observed in males but not females 1 wk after dose termination. Mean Co concentrations in whole blood/serum after 31 d of dosing were approximately two-fold higher in females (33/53 μg/L) than in males (16/21 μg/L). In general, steady-state concentrations of Co were achieved in whole blood and/or red blood cells (RBC) within 14-24 d. Temporal patterns of whole blood and serum Co concentrations indicated metal sequestration in RBC accompanied by slower whole blood clearance compared to serum. Data also indicated that peak whole blood Co concentrations up to 91.4 μg/L were not associated with clinically significant changes in clinical chemistries. In addition, Co blood concentrations and systemic uptake via ingestion were generally higher in females.

  13. Recent Advances of Cobalt(II/III) Redox Couples for Dye-Sensitized Solar Cell Applications.

    PubMed

    Giribabu, Lingamallu; Bolligarla, Ramababu; Panigrahi, Mallika

    2015-08-01

    In recent years dye-sensitized solar cells (DSSCs) have emerged as one of the alternatives for the global energy crisis. DSSCs have achieved a certified efficiency of >11% by using the I(-) /I3 (-) redox couple. In order to commercialize the technology almost all components of the device have to be improved. Among the various components of DSSCs, the redox couple that regenerates the oxidized sensitizer plays a crucial role in achieving high efficiency and durability of the cell. However, the I(-) /I3 (-) redox couple has certain limitations such as the absorption of triiodide up to 430 nm and the volatile nature of iodine, which also corrodes the silver-based current collectors. These limitations are obstructing the commercialization of this technology. For this reason, one has to identify alternative redox couples. In this regard, the Co(II/III) redox couple is found to be the best alternative to the existing I(-) /I3 (-) redox couple. Recently, DSSC test cell efficiency has risen up to 13% by using the cobalt redox couple. This review emphasizes the recent development of Co(II/III) redox couples for DSSC applications.

  14. Cobalt(II) chloride adducts with acetonitrile, propan-2-ol and tetrahydrofuran: considerations on nuclearity, reactivity and synthetic applications.

    PubMed

    Stinghen, Danilo; Rüdiger, André Luis; Giese, Siddhartha O K; Nunes, Giovana G; Soares, Jaísa F; Hughes, David L

    2017-02-01

    High-spin cobalt(II) complexes are considered useful building blocks for the synthesis of single-molecule magnets (SMM) because of their intrinsic magnetic anisotropy. In this work, three new cobalt(II) chloride adducts with labile ligands have been synthesized from anhydrous CoCl2, to be subsequently employed as starting materials for heterobimetallic compounds. The products were characterized by elemental, spectroscopic (EPR and FT-IR) and single-crystal X-ray diffraction analyses. trans-Tetrakis(acetonitrile-κN)bis(tetrahydrofuran-κO)cobalt(II) bis[(acetonitrile-κN)trichloridocobaltate(II)], [Co(C2H3N)4(C4H8O)2][CoCl3(C2H3N)]2, (1), comprises mononuclear ions and contains both acetonitrile and tetrahydrofuran (thf) ligands, The coordination polymer catena-poly[[tetrakis(propan-2-ol-κO)cobalt(II)]-μ-chlorido-[dichloridocobalt(II)]-μ-chlorido], [Co2Cl4(C3H8O)4], (2'), was prepared by direct reaction between anhydrous CoCl2 and propan-2-ol in an attempt to rationalize the formation of the CoCl2-alcohol adduct (2), probably CoCl2(HO(i)Pr)m. The binuclear complex di-μ-chlorido-1:2κ(4)Cl:Cl-dichlorido-2κ(2)Cl-tetrakis(tetrahydrofuran-1κO)dicobalt(II), [Co2Cl4(C4H8O)4], (3), was obtained from (2) after recrystallization from tetrahydrofuran. All three products present cobalt(II) centres in both octahedral and tetrahedral environments, the former usually less distorted than the latter, regardless of the nature of the neutral ligand. Product (2') is stabilized by an intramolecular hydrogen-bond network that appears to favour a trans arrangement of the chloride ligands in the octahedral moiety; this differs from the cis disposition found in (3). The expected easy displacement of the bound solvent molecules from the metal coordination sphere makes the three compounds good candidates for suitable starting materials in a number of synthetic applications.

  15. Cobalt(II) and Nickel(II) Transfer through Charged Polysulfonated Cation Exchange Membranes.

    PubMed

    Ersoz; Kara

    2000-12-15

    The transport of Co(II) and Ni(II) ions through charged polysulfonated ion exchange membranes under Donnan dialysis conditions has been studied as a function of pH gradient at 25 degrees C. In the Donnan dialysis process, the membrane is bounded by two electrolyte solutions, the one side (donor phase) initially containing metal salts and the other H(2)SO(4) with no external potential field applied. The transport of metal ions through membranes was correlated with the flux data as well as with estimated diffusion coefficients and was found to depend on the interaction between the fixed groups in the membrane and the metal ions. It was observed that the pH gradient influences the transport of metals and the flux of ions increases with H ion concentration in the receiver phase. Copyright 2000 Academic Press.

  16. Biosorption of cobalt(II) with sunflower biomass from aqueous solutions in a fixed bed column and neural networks modelling.

    PubMed

    Oguz, Ensar; Ersoy, Muhammed

    2014-01-01

    The effects of inlet cobalt(II) concentration (20-60 ppm), feed flow rate (8-19 ml/min) and bed height (5-15 cm), initial solution pH (3-5) and particle size (0.25cobalt(II) concentration, 5 cm bed height and 8 ml/min flow rate, pH 6.5 and 0.25cobalt(II) in fixed bed columns.

  17. Quinolones and non-steroidal anti-inflammatory drugs interacting with copper(II), nickel(II), cobalt(II) and zinc(II): structural features, biological evaluation and perspectives.

    PubMed

    Psomas, George; Kessissoglou, Dimitris P

    2013-05-14

    The structural features of copper(II), nickel(II), cobalt(II) and zinc(II) complexes with the antimicrobial drugs quinolones and non-steroidal anti-inflammatory drugs (NSAIDs) as ligands are discussed. The binding properties of these complexes to biomolecules (calf-thymus DNA, bovine or human serum albumin) are presented and evaluated. The biological activity (antimicrobial, antioxidant and antiproliferative) of selected complexes is investigated. Further perspectives concerning the synthesis and the biological activity of novel complexes with quinolones or NSAIDs attractive to synthetic chemists, biochemists and/or biologists are presented.

  18. Cobalt(II/III) redox electrolyte in ZnO nanowire-based dye-sensitized solar cells.

    PubMed

    Fan, Jiandong; Hao, Yan; Cabot, Andreu; Johansson, Erik M J; Boschloo, Gerrit; Hagfeldt, Anders

    2013-03-01

    In this work, we explore the use of cobalt complex redox shuttles in dye sensitized solar cells (DSCs) based on ZnO nanowires (NWs). Arrays of vertically aligned ZnO NWs produced by a low-cost hydrothermal method are used to fabricate DSCs with [Co(bpy)3](2+/3+) as electrolyte. A direct comparison of the performance of [Co(bpy)3](2+/3+)-based ZnO DSC with I(-)/I3(-)-based ones demonstrates the higher suitability of the cobalt complex, both in terms of a larger open circuit voltage (VOC) and a higher photocurrent. The [Co(bpy)3](2+/3+) electrolyte results in VOC enhancements above 200 mV. This VOC increase is associated to the better match between the cobalt complex redox potential and the oxidation potential of the dye. The incident photon-to-current efficiency (IPCE) enhancement is attributed to a less competitive visible light absorption of the cobalt redox couple. Thus the present study opens new opportunities to improve energy conversion efficiency in ZnO-based DSCs.

  19. trans-Dichlorido­tetra­kis­[(di­methyl­phosphor­yl)methanaminium-κO]cobalt(II) tetra­chloridocobaltate(II)

    PubMed Central

    Reiss, Guido J.

    2013-01-01

    The asymmetric unit of the title structure, [CoCl2(C3H11NOP)4][CoCl4]2, consists of one half of the trans-dichlorido­tetra­kis­[(di­methyl­phosphor­yl)methanaminium]cobalt(II) tetra­cation lying on an inversion center and one tetra­chloridocobaltate(II) dianion on a general position. Four O-coordinated cationic (di­methyl­phosphor­yl)methanaminium (dpmaH+) ligands occupy the equatorial coordination sites, whereas the chloride ligands occupy axial positions of the roughly o­cta­hedral coordination polyhedron of the cobalt metal center. Intra­molecular hydrogen bonds between the aminium groups and the O atom of the phosphoryl groups and additional hydrogen bonds between the aminium groups and the chloride ligands are present. Furthermore, four of the six H atoms not involved in intra­molecular bonding of each cobalt(II) tetra­cation form weak hydrogen bonds to four adjacent tetra­chloridocobaltate(II) counter-anions. By these inter­molecular hydrogen bonds, one-dimensional polymeric strands are formed along the b-axis direction. The hydrogen bonding is analyzed using the graph-set method and the structural similarity with dpmaHCl is discussed. PMID:23723763

  20. Sorption of lead (II), cobalt (II) and copper (II) ions from aqueous solutions by γ-MnO2 nanostructure

    NASA Astrophysics Data System (ADS)

    Chung Le, Ngoc; Van Phuc, Dinh

    2015-01-01

    Manganese dioxide γ-MnO2 was synthesized via the reduction-oxidation reaction between KMnO4 and C2H5OH at room temperature and characterized with x-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmet-Teller nitrogen adsorption (BET-N2 adsorption). The results showed that γ-MnO2 was about 10-18 nm in size and the BET surface area was about 65 m2 g-1. The feasibility of γ-MnO2 used as a low cost adsorbent for the adsorption of Pb(II), Co(II) and Cu(II) from aqueous solutions was explored. During the adsorption process, batch technique was used, and the effects of contact time and pH on adsorption efficiency under room temperature were studied. The adsorption data showed that the Freundlich, Langmuir and Redlich-Peterson isotherms are a good model for the sorption of Co(II) and Cu(II), while the Langmuir and Redlich-Peterson isotherms provide a reasonable fit to the experimental data for Pb(II). By using the Langmuir isotherm, the adsorption capacities for Pb(II), Co(II) and Cu(II) are found to be 200 mg g-1, 90.91 mg g-1 and 83.33 mg g-1, respectively. The effectiveness of γ-MnO2 in the sorption of the three metal ions from aqueous system has the order Pb(II) > Co(II) > Cu(II). Kinetic studies showed that a pseudo-second-order model was more suitable than the pseudo-first-order model. Also, the intra-particle diffusion models were used to ascertain the mechanism of the sorption process. It is concluded that γ-MnO2 can be used as an effective adsorbent for removing Pb(II), Co(II) and Cu(II) from aqueous solutions.

  1. Photoinduced hydrogen evolution with new tetradentate cobalt(ii) complexes based on the TPMA ligand.

    PubMed

    Natali, Mirco; Badetti, Elena; Deponti, Elisa; Gamberoni, Marta; Scaramuzzo, Francesca A; Sartorel, Andrea; Zonta, Cristiano

    2016-10-07

    Hydrogen production from water splitting is nowadays recognized as a target, fundamental reaction for the production of clean fuels. Indeed, tremendous efforts have been devoted towards the research of suitable catalysts capable of performing this reaction. With respect to heterogeneous systems, molecular catalysts such as metal complexes are amenable to chemical functionalization in order to fine tune the catalytic properties. In this paper a new class of tris(2-pyridylmethyl)-amine (TPMA) cobalt(ii) complexes (CoL0-4) has been synthesized and employed as hydrogen evolving catalysts under photochemical conditions taking advantage of Ru(bpy)3(2+) (where bpy is 2,2'-bipyridine) as a light-harvesting sensitizer and ascorbic acid as a sacrificial electron donor. Tuning of the photocatalytic activity has been attempted through the introduction of different substituents at the catalyst periphery rather than through a direct chemical modification of the chelating TPMA ligand. The results show that CoL0-4 behave as competent hydrogen evolving catalysts (HECs), although the effects played by the different substituents on the catalysis are relatively modest. Possible reasons supporting the observed behavior as well as possible improvements of the aforementioned tuning approach are discussed.

  2. EPR study of Cu(2+) ion doped orotato(nicotinamid)cobalt(II) single crystal.

    PubMed

    Yıldırım, I; Karabulut, B; Büyükgüngör, O

    2016-01-05

    We have studied the Cu(2+) ion doped orotato(nicotinamid)cobalt(II) complex by using EPR spectroscopy and X-ray diffraction. The single crystal is triclinic with the space group P1‾. The unit cell dimensions of the crystal are a=7.2785(4)Å, b=10.2349(5)Å, c=12.7372(6)Å, α=69.297(4)°, β=74.791(4)° and γ=76.995(4)°, with Z=2. We analyzed the EPR spectra of both single crystal and powder of the complex at room temperature. EPR analysis indicates the presence of only one Cu(2+) site. We obtained the spin Hamiltonian parameters from the single crystal data for the complex. The spin Hamiltonian parameters are gx=2.032, gy=2.116, gz=2.319, Ax=28G, Ay=66G, Az=126G. These data indicate that the symmetry of paramagnetic center is rhombic. We constructed the ground state wave function of the Cu(2+) ion.

  3. Aspartic acid interaction with cobalt(II) in dilute aqueous solution: A 57Co emission Mössbauer spectroscopic study

    NASA Astrophysics Data System (ADS)

    Kamnev, Alexander A.; Tugarova, Anna V.; Kovács, Krisztina; Homonnay, Zoltan; Kuzmann, Erno; Vértes, Attila

    2012-03-01

    Emission (57Co) Mössbauer spectra of the aspartic acid—57CoCl2 system were measured at T = 80 K in frozen aqueous solution and in the form of a dried residue of this solution. The Mössbauer spectra, besides a weak contribution from after-effects, showed two Fe2 + /Co2 + components which were ascribed to octahedrally and tetrahedrally coordinated 57CoII microenvironments in the Asp-cobalt(II) complex. This dual coordination mode may be due to the involvement of the second terminal carboxylic group of aspartic acid in the coordination sphere of Co.

  4. Dynamic interactions of dissolution, surface adsorption, and precipitation in an aging cobalt(II)-clay-water system

    NASA Astrophysics Data System (ADS)

    Thompson, Hillary A.; Parks, George A.; Brown, Gordon E.

    1999-06-01

    We have studied the dynamic interactions of mineral dissolution, cation surface adsorption, and precipitation in aqueous slurries initially containing kaolinite and millimolar quantities of cobalt(II) in 0.1 molar NaNO 3 solution. Batch slurries spent an initial 24 hours at pH 4.2, then NaOH was added to increase pH to 7.8, where pH was maintained for several months. Dissolved Co, Al, and Si concentrations were monitored by ICP-MS; solid-phase products were characterized using EXAFS and TEM. At low pH, kaolinite dissolved, releasing Al and Si to solution. Aluminum hydroxide and aluminosilicate phases precipitated rapidly as pH increased. Cobalt uptake from solution began as pH increased and continued throughout the remainder of the experiment. Rapid surface adsorption and precipitation accounted for early Co uptake; much slower precipitation caused continued Co uptake. Cobalt adsorbed on kaolinite in the form of hydroxy-bridged polymers or multimers and precipitated as a hydrotalcite-like solid that contained aluminum ions derived from kaolinite and aluminum hydroxide dissolution. The cobalt hydrotalcite precipitate had the approximate stoichiometry [Co 6Al 2(OH) 16(A n-) 2/n], with nitrate or silicate anions occupying A sites. Precipitate particles were several nanometers in diameter and some probably precipitated homogeneously. Some of the Co originally adsorbed was later incorporated into precipitate. Slow kaolinite dissolution near neutral pH limited the rate of Co uptake by precipitation, thereby accounting for the slow second stage of Co uptake. Continued changes in solution composition indicate that even this relatively simple system did not reach equilibrium under fixed solution conditions after several months. For this set of conditions, cobalt hydrotalcite appears to be the stable Co-containing phase, and its precipitation can reduce dissolved metal ion concentrations below levels achievable by simple adsorption on kaolinite.

  5. Dynamic interactions of dissolution, surface adsorption, and precipitation in an aging cobalt(II)-clay-water system

    SciTech Connect

    Thompson, H.A.; Parks, G.A.; Brown, G.E. Jr. |

    1999-06-01

    The authors have studied the dynamic interactions of mineral dissolution, cation surface adsorption, and precipitation in aqueous slurries initially containing kaolinite and millimolar quantities of cobalt(II) in 0.1 molar NaNO{sub 3} solution. Batch slurries spent an initial 24 hours at pH 4.2, then NaOH was added to increase pH to 7.8, where pH was maintained for several months. Dissolved Co, Al, and Si concentrations were monitored by ICP-MS; solid-phase products were characterized using EXAFS and TEM. At low pH, kaolinite dissolved, releasing Al and Si to solution. Aluminum hydroxide and aluminosilicate phases precipitated rapidly as pH increased. Cobalt uptake from solution began as pH increased and continued throughout the remainder of the experiment. Rapid surface adsorption and precipitation accounted for early Co uptake; much slower precipitation caused continued Co uptake. Cobalt adsorbed on kaolinite in the form of hydroxy-bridged polymers or multimers and precipitated as a hydrotalcite-like solid that contained aluminum ions derived from kaolinite and aluminum hydroxide dissolution. The cobalt hydrotalcite precipitate had the approximate stoichiometry [Co{sub 6}Al{sub 2}(OH){sub 16}(N{sup n{minus}}){sub 2/n}], with nitrate or silicate anions occupying A sites. Precipitate particles were several nanometers in diameter and some probably precipitated homogeneously. Some of the Co originally adsorbed was later incorporated into precipitate. Slow kaolinite dissolution near neutral pH limited the rate of Co uptake by precipitation, thereby accounting for the slow second stage of Co uptake. Continued changes in solution composition indicate that even this relatively simple system did not reach equilibrium under fixed solution conditions after several months. For this set of conditions, cobalt hydrotalcite appears to be the stable Co-containing phase, and its precipitation can reduce dissolved metal ion concentrations below levels achievable by simple

  6. Synthesis and characterization of cobalt(II), nickel(II), copper(II) and zinc(II) complexes with Schiff base derived from 4-amino-3-mercapto-6-methyl-5-oxo-1,2,4-triazine.

    PubMed

    Singh, Kiran; Barwa, Manjeet Singh; Tyagi, Parikshit

    2007-03-01

    A few (1:1) and (1:2) metal complexes of cobalt(II), nickel(II), copper(II) and zinc(II) have been isolated with ligand derived from the condensation of 4-amino-3-mercapto-6-methyl-5-oxo-1,2,4-triazine with 2-acetylpyridine (L(1)) and characterized by elemental analysis, conductivity measurements, infrared, electronic, (1)H NMR spectral data, magnetic and thermogravimetric analyses. Due to insolubility in water and most of the common organic solvents and infusibility at higher temperatures, all the complexes are thought to be polymeric in nature. A square-planar geometry was suggested for copper(II) and octahedral proposed for cobalt(II), nickel(II) and zinc(II). Some of the chemically synthesized compounds have been screened in vitro against the three Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis) and two Gram-negative (Salmonella typhi and Escherichia coli) organisms. It is observed that the coordination of metal ion has pronounced effect on the microbial activities of the ligand. The metal complexes have higher antimicrobial effect than the free ligands.

  7. Biosorption of copper(II), lead(II), iron(III) and cobalt(II) on Bacillus sphaericus-loaded Diaion SP-850 resin.

    PubMed

    Tuzen, Mustafa; Uluozlu, Ozgur Dogan; Usta, Canan; Soylak, Mustafa

    2007-01-09

    The biosorption of copper(II), lead(II), iron(III) and cobalt(II) on Bacillus sphaericus-loaded Diaion SP-850 resin for preconcentration-separation of them have been investigated. The sorbed analytes on biosorbent were eluted by using 1 mol L(-1) HCl and analytes were determined by flame atomic absorption spectrometry. The influences of analytical parameters including amounts of pH, B. sphaericus, sample volume etc. on the quantitative recoveries of analytes were investigated. The effects of alkaline, earth alkaline ions and some metal ions on the retentions of the analytes on the biosorbent were also examined. Separation and preconcentration of Cu, Pb, Fe and Co ions from real samples was achieved quantitatively. The detection limits by 3 sigma for analyte ions were in the range of 0.20-0.75 microg L(-1) for aqueous samples and in the range of 2.5-9.4 ng g(-1) for solid samples. The validation of the procedure was performed by the analysis of the certified standard reference materials (NRCC-SLRS 4 Riverine Water, SRM 2711 Montana soil and GBW 07605 Tea). The presented method was applied to the determination of analyte ions in green tea, black tea, cultivated mushroom, boiled wheat, rice and soil samples with successfully results.

  8. Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand.

    PubMed

    Kamble, Ganesh S; Ghare, Anita A; Kolekar, Sanjay S; Han, Sung H; Anuse, Mansing A

    2011-12-15

    A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5-10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is 10 min for extraction of cobalt(III) from organic phase. The absorbance of coloured organic layer in chloroform is measured spectrophotometrically at 490 nm against reagent blank. The Beer's law was obeyed in the concentration range 2.5-15 μg mL(-1) of cobalt(II) and optimum concentration range was 5-12.5 μg mL(-1) of cobalt(II) and it was evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 1.109×10(3) L mol(-1) cm(-1) and 0.053 μg cm(-2), respectively while molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT complex in chloroform are 6.22×10(2) L mol(-1) cm(-1) and 0.096 μg cm(-2), respectively. The composition of cobalt(II)-2',4'-dinitro APTPT-pyridine complex (1:2:2) was established by slope ratio method, mole ratio method and Job's method of continuous variation. The ternary complex was stable for more than 48 h. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The method is successfully applied for the determination of cobalt(II) in binary, synthetic mixtures and real samples. A repetition of the method was checked by finding relative standard deviation (R.S.D.) for n=5 which was 0.15%. The reliability of the method is confirmed by comparison of experimental results with atomic absorption spectrophotometer.

  9. Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand

    NASA Astrophysics Data System (ADS)

    Kamble, Ganesh S.; Ghare, Anita A.; Kolekar, Sanjay S.; Han, Sung H.; Anuse, Mansing A.

    2011-12-01

    A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5-10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is 10 min for extraction of cobalt(III) from organic phase. The absorbance of coloured organic layer in chloroform is measured spectrophotometrically at 490 nm against reagent blank. The Beer's law was obeyed in the concentration range 2.5-15 μg mL -1 of cobalt(II) and optimum concentration range was 5-12.5 μg mL -1 of cobalt(II) and it was evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 1.109 × 10 3 L mol -1 cm -1 and 0.053 μg cm -2, respectively while molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT complex in chloroform are 6.22 × 10 2 L mol -1 cm -1 and 0.096 μg cm -2, respectively. The composition of cobalt(II)-2',4'-dinitro APTPT-pyridine complex (1:2:2) was established by slope ratio method, mole ratio method and Job's method of continuous variation. The ternary complex was stable for more than 48 h. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The method is successfully applied for the determination of cobalt(II) in binary, synthetic mixtures and real samples. A repetition of the method was checked by finding relative standard deviation (R.S.D.) for n = 5 which was 0.15%. The reliability of the method is confirmed by comparison of experimental results with atomic absorption spectrophotometer.

  10. /sup 111/In-oxine platelet survivals in thrombocytopenic infants

    SciTech Connect

    Castle, V.; Coates, G.; Kelton, J.G.; Andrew, M.

    1987-09-01

    Thrombocytopenia is a common occurrence (20%) in sick neonates, but the causes have not been well studied. In this report we demonstrate that thrombocytopenia in the neonate is characterized by increased platelet destruction as shown by shortened homologous /sup 111/In-oxine-labeled platelet life spans. Thirty-one prospectively studied thrombocytopenic neonates were investigated by measuring the /sup 111/In-labeled platelet life span, platelet-associated IgG (PAIgG), and coagulation screening tests. In every infant, the thrombocytopenia was shown to have a destructive component since the mean platelet life span was significantly shortened to 65 +/- 6 (mean +/- SEM) hours with a range of one to 128 hours compared with adult values (212 +/- 8; range, 140 to 260; gamma function analysis). The platelet survival was directly related to the lowest platelet count and inversely related to both the highest mean platelet volume and duration of the thrombocytopenia. In 22 infants the percent recovery of the radiolabeled platelets was less than 50%, which suggested that increased sequestration also contributed to the thrombocytopenia. Infants with laboratory evidence of disseminated intravascular coagulation (n = 8) or immune platelet destruction evidenced by elevated levels of PAIgG (n = 13) had even shorter platelet survivals and a more severe thrombocytopenia compared with the ten infants in whom an underlying cause for the thrombocytopenia was not apparent. Full-body scintigraphic images obtained in 11 infants showed an increased uptake in the spleen and liver, with a spleen-to-liver ratio of 3:1. This study indicates that thrombocytopenia in sick neonates is primarily destructive, with a subgroup having evidence of increased platelet sequestration.

  11. Cobalt (II) removal from aqueous solutions by natural hemp fibers: Batch and fixed-bed column studies

    NASA Astrophysics Data System (ADS)

    Tofan, Lavinia; Teodosiu, Carmen; Paduraru, Carmen; Wenkert, Rodica

    2013-11-01

    Natural hemp fibers were explored as sorbent for the removal of Co(II) ions from aqueous solutions in batch and dynamic conditions. The batch Co(II) sorption capacity increased up to pH 5, reached the maximum (7.5-7.8 mg/g) over the initial pH of 4.5-5. As the initial concentration of metal ion increased (in the range of 25-200 mg/L), the cobalt uptake was enhanced, but the Co(II) removal efficiency decreased. The batch sorption of Co(II) on the tested hemp follows a pseudo-second order model, which relies on the assumption that the chemisorptions may be the rate-controlling step. The Langmuir model better described the Co(II) sorption process on the natural hemp fibers in comparison with the Freundlich model. This finding complies with the results of fixed-bed studies which emphasize that the optimal solution for describing the behavior of the investigated hemp bed column is provided by the Thomas model. The sorption capacity of the hemp fibers column (15.44 mg/g) performed better than that of the Co(II)-hemp batch system (13.58 mg/g). The possibility to use hemp fibers as an alternative in the Co(II) wastewater treatment should be studied under pilot scale applications, so as to complete the studies concerning the removal efficiencies with technical and economic factors that influence process scale-up.

  12. Mercury-based cobalt magnetic fluids and cobalt nanoparticles

    NASA Astrophysics Data System (ADS)

    Massart, R.; Rasolonjatovo, B.; Neveu, S.; Cabuil, V.

    2007-01-01

    This paper describes the synthesis of a magnetic and conducting liquid consisting of cobalt nanoparticles dispersed in mercury. The magnetic nanoparticles are obtained in one step by the electroreduction of a cobalt(II) solution on mercury. These particles are then extracted using an organic solution of surfactant in order to obtain a ferrofluid based on cobalt nanoparticles.

  13. 2,6-Bis(2,6-diethylphenyliminomethyl)pyridine coordination compounds with cobalt(II), nickel(II), copper(II), and zinc(II): synthesis, spectroscopic characterization, X-ray study and in vitro cytotoxicity.

    PubMed

    Martinez-Bulit, Pablo; Garza-Ortíz, Ariadna; Mijangos, Edgar; Barrón-Sosa, Lidia; Sánchez-Bartéz, Francisco; Gracia-Mora, Isabel; Flores-Parra, Angelina; Contreras, Rosalinda; Reedijk, Jan; Barba-Behrens, Norah

    2015-01-01

    Coordination compounds with cobalt(II), nickel(II), copper(II) and zinc(II) and the ligand 2,6-bis(2,6-diethylphenyliminomethyl)pyridine (L) were synthesized and fully characterized by IR and UV-Vis-NIR spectroscopy, elemental analysis, magnetic susceptibility and X-ray diffraction for two representative cases. These novel compounds were designed to study their activity as anti-proliferative drugs against different human cancer cell lines. The tridentate ligand forms heptacoordinated compounds from nitrate metallic salts, where the nitrate acts in a chelating form to complete the seven coordination positions. In vitro cell growth inhibition was measured for Co(II), Cu(II) and Zn(II) complexes, as well as for the free ligand. Upon coordination, the IC50 value of the transition-metal compounds is improved compared to the free ligand. The copper(II) and zinc(II) compounds are the most promising candidates for further in vitro and in vivo studies. The activity against colon and prostate cell lines merits further research, in views of the limited therapeutic options for such cancer types.

  14. Binuclear cobalt(II), nickel(II), copper(II) and palladium(II) complexes of a new Schiff-base as ligand: synthesis, structural characterization, and antibacterial activity.

    PubMed

    Geeta, B; Shravankumar, K; Reddy, P Muralidhar; Ravikrishna, E; Sarangapani, M; Reddy, K Krishna; Ravinder, V

    2010-11-01

    A binucleating new Schiff-base ligand with a phenylene spacer, afforded by the condensation of glycyl-glycine and o-phthalaldehyde has been served as an octadentate N₄O₄ ligand in designing some binuclear complexes of cobalt(II), nickel(II), copper(II), and palladium(II). The binding manner of the ligand to the metal and the composition and geometry of the metal complexes were examined by elemental analysis, conductivity measurements, magnetic moments, IR, ¹H, ¹³C NMR, ESR and electronic spectroscopies, and TGA measurements. There are two different coordination/chelation environments present around two metal centers of each binuclear complex. The composition of the complexes in the coordination sphere was found to be [M₂(L)(H(2)O)₄] (where M=Co(II) and Ni(II)) and [M₂(L)] (where M=Cu(II) and Pd(II)). In the case of Cu(II) complexes, ESR spectra provided further information to confirm the binuclear structure and the presence of magnetic interactions. All the above metal complexes have shown moderate to good antibacterial activity against Gram-positive and Gram-negative bacteria.

  15. Penta­cobalt(II) divanadium(III) tetrakis(diphosphate), Co5V2(P2O7)4

    PubMed Central

    Bronova, Anna; Glaum, Robert; Litterscheid, Christian

    2013-01-01

    Co5V2(P2O7)4 was crystallized by chemical vapour transport using HCl as transport agent. Its crystal structure is isotypic to that of FeII 5FeIII 2(P2O7)4 and can be regarded as a member of the thortveitite structure family with corrugated layers of metal–oxygen polyhedra extending parallel to (010). Significant occupational disorder between cobalt(II) and vanadium(III) is observed. Four of the five cation sites are occupied by both cobalt and vanadium. The fifth cation site (Co1) is occupied by cobalt only. Sites Co1, M3 and M4 are located on twofold axes. Sites Co1, M2, M3 and M4 show o­cta­hedral coordination by oxygen; M5 has a square-pyramidal environment. PMID:23723750

  16. A controllable gate effect in cobalt(II) organic frameworks by reversible structure transformations.

    PubMed

    Chen, Qiang; Chang, Ze; Song, Wei-Chao; Song, Han; Song, Hai-Bin; Hu, Tong-Liang; Bu, Xian-He

    2013-10-25

    With H2 O or NH3 stimuli, the blue cobalt-based metal-organic framework (MOF) BP can reversibly transform to red RP. The removal/recovery of terephthalate ligands accompanied by the transformation leads to a gate effect, which allows the encapsulation and release of small solvent molecules under certain conditions. This is the first example of topology transformation from a self-penetrating to interpenetrating net in 3D MOFs.

  17. Carbonaceous material obtained from exhausted coffee by an aqueous solution combustion process and used for cobalt (II) and cadmium (II) sorption.

    PubMed

    Serrano-Gómez, J; López-González, H; Olguín, M T; Bulbulian, S

    2015-06-01

    New carbonaceous materials were obtained using a fast aqueous solution combustion process from mixtures of exhausted coffee, ammonium nitrate (oxidizer) and urea (fuel) heated at 600, 700, 800 or 900 °C. The resulting powders were effective adsorbents for removing Co(II) and Cd(II) from aqueous solutions. Exhausted coffee was also calcined at different temperatures and compared. The products were characterized, and the obtained carbons had BET specific surface areas of 114.27-390.85 m(2)/g and pore diameters of 4.19 to 2.44 nm when the temperature was increased from 600 to 800 °C. Cobalt and cadmium adsorption by the carbonaceous materials was correlated with the maximum adsorption capacities and specific surface areas of the materials. The method reported here is advantageous because it only required 5 min of reaction to improve the textural properties of carbon obtained from exhausted coffee, which play an important role in the material's cobalt and cadmium adsorption capacities.

  18. Aromatic carboxylate effect on dimensionality of three bis(benzimidazole)-based cobalt(II) coordination polymers: Syntheses, structures and properties

    SciTech Connect

    Zhang, Ju-Wen; Gong, Chun-Hua; Hou, Li-Li; Tian, Ai-Xiang; Wang, Xiu-Li

    2013-09-15

    Three new metal-organic coordination polymers [Co(4-bbc){sub 2}(bbbm)] (1), [Co(3,5-pdc)(bbbm)]·2H{sub 2}O (2) and [Co(1,4-ndc)(bbbm)] (3) (4-Hbbc=4-bromobenzoic acid, 3,5-H{sub 2}pdc=3,5-pyridinedicarboxylic acid, 1,4-H{sub 2}ndc=1,4-naphthalenedicarboxylic acid and bbbm=1,1-(1,4-butanediyl)bis-1H-benzimidazole) were hydrothermally synthesized and structurally characterized. Polymer 1 is a 1D chain formed by the bbbm ligands and Co{sup II} ions. Polymer 2 exhibits a 2D network with a (3·4·5)(3{sup 2}·4·5·6{sup 2}·7{sup 4}) topology. Polymer 3 possesses a 3D three-fold interpenetrating framework. The versatile structures of title polymers indicate that the aromatic carboxylates have an important influence on the dimensionality of 1–3. Moreover, the thermal stability, electrochemical and luminescent properties of 1–3 were investigated. - graphical abstract: Three bis(benzimidazole)-based cobalt(II) coordination polymers tuned by aromatic carboxylates were hydrothermally synthesized and structurally characterized. The aromatic carboxylates play a key role in the dimensionality of three polymers. The electrochemical and luminescent properties of three polymers were investigated. Display Omitted - Highlights: • Three bis(benzimidazole)-based cobalt(II) coordination polymers tuned by aromatic carboxylates were obtained. • The aromatic carboxylates have an important influence on the dimensionality of three polymers. • The electrochemical and luminescent properties of three polymers were investigated.

  19. Pharmacological Role of Anions (Sulphate, Nitrate, Oxalate and Acetate) on the Antibacterial Activity of Cobalt(II), Copper(II) and Nickel(II) Complexes With Nicotinoylhydrazine-Derived ONO, NNO and SNO Ligands

    PubMed Central

    Rauf, Abdur

    1996-01-01

    Mixed ligands biologically active complexes of cobalt(II), copper(II) and nickel(II) with nicotinoylhydrazine-derived ONO, NNO and SNO donor schiff-base ligands having the same metal ion but different anions such as sulphate, nitrate, oxalate and acetate have been synthesised and characterised on the basis of their physical, analytical and spectral data. In order to evaluate the role of anions on their bioability, these ligands and their synthesised metal complexes with various anions have been screened against bacterial species such as Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus and the title studies have proved a definative role of anions in increasing the biological activity PMID:18472896

  20. Three cobalt(II)-linked {P8W48} network assemblies: syntheses, structures, and magnetic and photocatalysis properties.

    PubMed

    Jiao, Yan-Qing; Qin, Chao; Wang, Xin-Long; Wang, Chun-Gang; Sun, Chun-Yi; Wang, Hai-Ning; Shao, Kui-Zhan; Su, Zhong-Min

    2014-02-01

    Three cobalt(II)-containing tungstophosphate compounds, Na8Li8Co5[Co5.5(H2O)19P8W48.5O184]⋅60 H2O (1), K2Na4Li11Co5[Co7(H2O)28P8W48O184]Cl⋅ 59 H2O (2), and K2Na4LiCo11[Co8(H2O)32P8W48O184](CH3COO)4Cl⋅47 H2O (3), have been synthesized and characterized by IR spectroscopy, thermogravimetric analysis, elemental analyses, and magnetic measurements. The pH value impacts the formation of distinct cobalt-linked frameworks. The cyclic cavity of the polyanion accommodates 5.5, 7, and 8 cobalt ions in 1, 2, and 3, respectively. In compounds 1 and 2, each {Co5.5P8W48} and {Co7P8W48} fragment links to four others through multiple {Co-O-W} coordination bonds to generate a two-dimensional network. Compound 3 can be considered as a 3D network based on the {Co-O-W} coordination bonds and the {Co3(CH3COO)2(H2O)10} linkers between the {P8W48} fragments. Interestingly, acetate ligands have been employed to form the {Co3(CH3COO)2(H2O)10} unit, thereby inducing the construction of a 12-connected framework. To the best of our knowledge, compound 3 contains the largest-ever number of cobalt ions in a {P8W48}-based polyoxometalate when counterions are taken into account and the {P8W48} unit shows the highest number of connections thanks to the carboxyl bridges. The UV/Vis diffuse reflectance spectra of these powder samples indicate that the corresponding well-defined optical absorption associated with Eg can be assessed at 2.58, 2.48, and 2.73 eV and reveal the presence of an optical band gap. The photocatalytic H2 evolution activities of these {P8W48}-based compounds are evaluated.

  1. Bis[bis­(penta­methyl­cyclo­penta­dien­yl)cobalt(III)] tetra­chlorido­cobaltate(II) di­chloro­methane disolvate

    PubMed Central

    Merola, Joseph S.; Ngo, Mai; Karpin, George W.

    2013-01-01

    The title compound, [Co(C10H15)2]2[CoCl4]·2CH2Cl2, was isolated as a dichloromethane solvate and was formed in the reaction between lithium penta­methyl­cyclo­penta­dienide and anyhydrous cobalt(II) chloride in tetra­hydro­furan. There are two deca­methyl­cobaltocenium cations, one tetrachloridocobaltate(II) anion and two di­chloro­methane solvent mol­ecules in the formula unit. There is a slight disorder of the di­chloro­methane solvent which was treated with a two-site model [occupancy rates = 0.765 (4) and 0.235 (4)]. The di­chloro­methane mol­ecules display significant C—H⋯Cl inter­actions with the tetrachloridocobaltate(II) dianion. The cobalt atom of the deca­methyl­cobaltocenium cation sits on a twofold rotation axis, with only one penta­methyl­cyclo­penta­diene ligand being unique and the second generated by symmetry. The cobalt atom of the [CoCl4]−2 ion sits on a special site with -4 symmetry, with one unique chloride ligand and the others generated by the fourfold inversion axis. PMID:24426998

  2. Synthesis and characterization of iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of salicylidene-N-anilinoacetohydrazone (H2L1) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H2L2).

    PubMed

    AbouEl-Enein, S A; El-Saied, F A; Kasher, T I; El-Wardany, A H

    2007-07-01

    Salicylidene-N-anilinoacetohydrazone (H(2)L(1)) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H(2)L(2)) and their iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes have been synthesized and characterized by IR, electronic spectra, molar conductivities, magnetic susceptibilities and ESR. Mononuclear complexes are formed with molar ratios of 1:1, 1:2 and 1:3 (M:L). The IR studies reveal various modes of chelation. The electronic absorption spectra and magnetic susceptibility measurements show that the iron(III), nickel(II) and cobalt(II) complexes of H(2)L(1) have octahedral geometry. While the cobalt(II) complexes of H(2)L(2) were separated as tetrahedral structure. The copper(II) complexes have square planar stereochemistry. The ESR parameters of the copper(II) complexes at room temperature were calculated. The g values for copper(II) complexes proved that the Cu-O and Cu-N bonds are of high covalency.

  3. Optical, thermal, mechanical and dielectric properties of hexakis(urea)cobalt(II) sulfate monohydrate: A semiorganic crystal

    NASA Astrophysics Data System (ADS)

    Muthu, K.; Rajasekar, M.; Meenakshisundaram, SP.

    2013-04-01

    Single crystals of hexakis(urea)cobalt(II) sulfate monohydrate have been grown by slow evaporation solution growth technique at room temperature. The single crystal X-ray diffraction study reveals that the crystal belongs to orthorhombic system with noncentrosymmetric space group Pca21 and the cell parameters are, a=15.0549(6) Å, b=7.2105(3) Å, c=20.0284(9) Å, V=2174.15 (16) Å3 and Z=4. The functional groups of the metal-urea complex were confirmed by Fourier transform infrared spectroscopy. The powder X-ray diffraction study reveals the crystallinity of the as-grown material. The band-gap energy of the specimen is estimated by Kubelka-Munk algorithm. The dielectric results indicate an increase in dielectric and conductivity parameters with an increase of temperature at all frequencies. The crystal is further characterized by mechanical and thermal analysis.

  4. Molecular, crystal, and electronic structure of the cobalt(II) complex with 10-(2-benzothiazolylazo)-9-phenanthrol

    NASA Astrophysics Data System (ADS)

    Linko, R. V.; Sokol, V. I.; Polyanskaya, N. A.; Ryabov, M. A.; Strashnov, P. V.; Davydov, V. V.; Sergienko, V. S.

    2013-05-01

    The reaction of 10-(2-benzothiazolylazo)-9-phenanthrol (H L) with cobalt(II) acetate gives the coordination compound [Co L 2] · CHCl3 ( I). The molecular and crystal structure of I is determined by X-ray diffraction. The coordination polyhedron of the Co atom in complex I is an octahedron. The anion L acts as a tridentate chelating ligand and is coordinated to the Co atom through the phenanthrenequinone O1 atom and the benzothiazole N1 atom of the moieties L and the N3 atom of the azo group to form two five-membered metallocycles. The molecular and electronic structures of the compounds H L, L, and Co L 2 are studied at the density functional theory level. The results of the quantum-chemical calculations are in good agreement with the values determined by X-ray diffraction.

  5. Studies on the sorption of praseodymium (III), holmium (III) and cobalt (II) from nitrate medium using TVEX-PHOR resin.

    PubMed

    El-Dessouky, S I; El-Sofany, E A; Daoud, J A

    2007-05-08

    The use of TVEX-PHOR resin for the sorption of praseodymium (III), holmium (III) and cobalt (II) from nitrate medium was carried out using batch and column techniques. Various parameters affecting the uptake of these metal ions such as v/m ratio, pH and the metal ion concentration were separately studied. Effect of temperature on the equilibrium distribution values has been studied to evaluate the changes in standard thermodynamic quantities. Experimental results of the investigated metal ions were found to fit to Freundlich isotherm model over the entire studied concentration range. Selectivity sequence of the resin for these metals is Ho>Pr>Co. The recovery of the investigated metals from the loaded resin is preformed with 0.1M sulphuric acid.

  6. Porphyrin-sensitized solar cells with cobalt (II/III)-based redox electrolyte exceed 12 percent efficiency.

    PubMed

    Yella, Aswani; Lee, Hsuan-Wei; Tsao, Hoi Nok; Yi, Chenyi; Chandiran, Aravind Kumar; Nazeeruddin, Md Khaja; Diau, Eric Wei-Guang; Yeh, Chen-Yu; Zakeeruddin, Shaik M; Grätzel, Michael

    2011-11-04

    The iodide/triiodide redox shuttle has limited the efficiencies accessible in dye-sensitized solar cells. Here, we report mesoscopic solar cells that incorporate a Co((II/III))tris(bipyridyl)-based redox electrolyte in conjunction with a custom synthesized donor-π-bridge-acceptor zinc porphyrin dye as sensitizer (designated YD2-o-C8). The specific molecular design of YD2-o-C8 greatly retards the rate of interfacial back electron transfer from the conduction band of the nanocrystalline titanium dioxide film to the oxidized cobalt mediator, which enables attainment of strikingly high photovoltages approaching 1 volt. Because the YD2-o-C8 porphyrin harvests sunlight across the visible spectrum, large photocurrents are generated. Cosensitization of YD2-o-C8 with another organic dye further enhances the performance of the device, leading to a measured power conversion efficiency of 12.3% under simulated air mass 1.5 global sunlight.

  7. Assembling an alkyl rotor to access abrupt and reversible crystalline deformation of a cobalt(II) complex.

    PubMed

    Su, Sheng-Qun; Kamachi, Takashi; Yao, Zi-Shuo; Huang, You-Gui; Shiota, Yoshihito; Yoshizawa, Kazunari; Azuma, Nobuaki; Miyazaki, Yuji; Nakano, Motohiro; Maruta, Goro; Takeda, Sadamu; Kang, Soonchul; Kanegawa, Shinji; Sato, Osamu

    2015-11-04

    Harnessing molecular motion to reversibly control macroscopic properties, such as shape and size, is a fascinating and challenging subject in materials science. Here we design a crystalline cobalt(II) complex with an n-butyl group on its ligands, which exhibits a reversible crystal deformation at a structural phase transition temperature. In the low-temperature phase, the molecular motion of the n-butyl group freezes. On heating, the n-butyl group rotates ca. 100° around the C-C bond resulting in 6-7% expansion of the crystal size along the molecular packing direction. Importantly, crystal deformation is repeatedly observed without breaking the single-crystal state even though the shape change is considerable. Detailed structural analysis allows us to elucidate the underlying mechanism of this deformation. This work may mark a step towards converting the alkyl rotation to the macroscopic deformation in crystalline solids.

  8. A four-coordinate cobalt(II) single-ion magnet with coercivity and a very high energy barrier

    PubMed Central

    Rechkemmer, Yvonne; Breitgoff, Frauke D.; van der Meer, Margarethe; Atanasov, Mihail; Hakl, Michael; Orlita, Milan; Neugebauer, Petr; Sarkar, Biprajit; van Slageren, Joris

    2016-01-01

    Single-molecule magnets display magnetic bistability of molecular origin, which may one day be exploited in magnetic data storage devices. Recently it was realised that increasing the magnetic moment of polynuclear molecules does not automatically lead to a substantial increase in magnetic bistability. Attention has thus increasingly focussed on ions with large magnetic anisotropies, especially lanthanides. In spite of large effective energy barriers towards relaxation of the magnetic moment, this has so far not led to a big increase in magnetic bistability. Here we present a comprehensive study of a mononuclear, tetrahedrally coordinated cobalt(II) single-molecule magnet, which has a very high effective energy barrier and displays pronounced magnetic bistability. The combined experimental-theoretical approach enables an in-depth understanding of the origin of these favourable properties, which are shown to arise from a strong ligand field in combination with axial distortion. Our findings allow formulation of clear design principles for improved materials. PMID:26883902

  9. What Controls the Sign and Magnitude of Magnetic Anisotropy in Tetrahedral Cobalt(II) Single-Ion Magnets?

    PubMed

    Vaidya, Shefali; Tewary, Subrata; Singh, Saurabh Kumar; Langley, Stuart K; Murray, Keith S; Lan, Yanhua; Wernsdorfer, Wolfgang; Rajaraman, Gopalan; Shanmugam, Maheswaran

    2016-10-03

    A family of mononuclear tetrahedral cobalt(II) thiourea complexes, [Co(L1)4](NO3)2 (1) and [Co(Lx)4](ClO4)2 where x = 2 (2), 3 (3), 4 (4) (where L1 = thiourea, L2 = 1,3-dibutylthiourea, L3 = 1,3-phenylethylthiourea, and L4 = 1,1,3,3-tetramethylthiourea), has been synthesized using a rationally designed synthetic approach, with the aim of stabilizing an Ising-type magnetic anisotropy (-D). On the basis of direct-current, alternating-current, and hysteresis magnetic measurements and theoretical calculations, we have identified the factors that govern the sign and magnitude of D and ultimately the ability to design a single-ion magnet for a tetrahedral cobalt(II) ion. To better understand the magnetization relaxation dynamics, particularly for complexes 1 and 2, dilution experiments were performed using their diamagnetic analogues, which are characterized by single-crystal X-ray diffraction with the general molecular formulas of [Zn(L1)4](NO3)2 (5) and [Zn(L2)4](ClO4)2 (6). Interestingly, intermolecular interactions are shown to play a role in quenching the quantum tunneling of magnetization in zero field, as evidenced in the hysteresis loop of 1. Complex 2 exhibits the largest Ueff value of 62 cm(-1) and reveals open hysteresis loops below 4 K. Furthermore, the influence of the hyperfine interaction on the magnetization relaxation dynamics is witnessed in the hysteresis loops, allowing us to determine the electron/nuclear spin S(Co) = (3)/2/I(Co) = (7)/2 hyperfine coupling constant of 550 MHz, a method ideally suited to determine the hyperfine coupling constant of highly anisotropic metal ions stabilized with large D value, which are otherwise hard to determine by conventional methods such as electron paramagnetic resonance.

  10. Syntheses, structures and magnetic properties of two new one-dimensional cobalt (II) phosphites with organic amines acting as ligands

    SciTech Connect

    Li Gaijuan; Xing Yan Song Shuyan

    2008-04-15

    Two new one-dimensional (1D) inorganic-organic hybrid cobalt (II) phosphites Co(HPO{sub 3}) (py) (1) and [Co(OH)(py){sub 3}][Co(py){sub 2}][HPO{sub 2}(OH)]{sub 3} (2) have been prepared under solvothermal conditions in the presence of pyridine (py). Compound 1 crystallizes in the monoclinic system, space group p2(1)/c, a=5.3577(7) A, b=7.7503(10) A, c=17.816(2) A, {beta}=94.327(2){sup o}, V=737.67(16) A{sup 3}, Z=4. Compound 2 is orthorhombic, Cmcm, a=16.3252(18) A, b=15.7005(16) A, c=13.0440(13) A, {beta}=90.00{sup o}V=3343.4(6) A{sup 3} and Z=4. Compound 1 possesses a 1D ladder-like framework constructed from CoO{sub 3}N tetrahedral, HPO{sub 3} pseudo-pyramids and pyridine ligands. While compound 2 is an unusual inorganic-organic hybrid 1D chain, which consists of corner-shared six-membered rings made of CoO{sub 3}N{sub 3}/CoO{sub 4}N{sub 2} octahedra and HPO{sub 3} pseudo-pyramids through sharing vertices. - Graphical abstract: Two new 1D inorganic-organic hybrid cobalt (II) phosphites have been prepared under solvothermal conditions in the presence of pyridine. Co(HPO{sub 3}) (py) possesses a 1D ladder-like framework constructed from CoO{sub 3}N tetrahedral, HPO{sub 3} pseudo-pyramids and pyridine ligands (left); 1D-chain structure of [Co(OH)(py){sub 3}][Co(py){sub 2}][HPO{sub 2}(OH)]{sub 3} consists of corner-shared six-membered rings (right)

  11. The Porphyromonas gingivalis HmuY haemophore binds gallium(iii), zinc(ii), cobalt(iii), manganese(iii), nickel(ii), and copper(ii) protoporphyrin IX but in a manner different to iron(iii) protoporphyrin IX.

    PubMed

    Wójtowicz, Halina; Bielecki, Marcin; Wojaczyński, Jacek; Olczak, Mariusz; Smalley, John W; Olczak, Teresa

    2013-04-01

    Porphyromonas gingivalis, a major etiological agent of chronic periodontitis, acquires haem from host haemoproteins through a haem transporter HmuR and a haemophore HmuY. The aim of this study was to analyse the binding specificity of HmuY towards non-iron metalloporphyrins which may be employed as antimicrobials to treat periodontitis. HmuY binds gallium(iii), zinc(ii), cobalt(iii), manganese(iii), nickel(ii), and copper(ii) protoporphyrin IX but in a manner different to iron(iii) protoporphyrin IX which uses His(134) and His(166) as axial ligands. The metal ions in Ga(iii)PPIX and Zn(ii)PPIX can accept only His(166) as an axial ligand, whereas nickel(ii) and copper(ii) interact exclusively with His(134). Two forms of pentacoordinate manganese(iii) are present in the Mn(iii)PPIX-HmuY complex since the metal accepts either His(134) or His(166) as a single axial ligand. The cobalt ion is hexacoordinate in the Co(iii)PPIX-HmuY complex and binds His(134) and His(166) as axial ligands; however, some differences in their environments exist. Despite different coordination modes of the central metal ion, gallium(iii), zinc(ii), cobalt(iii), and manganese(iii) protoporphyrin IX bound to the HmuY haemophore cannot be displaced by excess haem. All of the metalloporphyrins examined bind to a P. gingivalis wild-type strain with higher ability compared to a mutant strain lacking a functional hmuY gene, thus corroborating binding of non-iron metalloporphyrins to purified HmuY protein. Our results further clarify the basis of metalloporphyrin acquisition by P. gingivalis and add to understanding of the interactions with porphyrin derivatives which exhibit antimicrobial activity against P. gingivalis.

  12. Ternary complexes of copper(II) and cobalt(II) involving nitrite/pyrazole and tetradentate N4-coordinate ligand: Synthesis, characterization, structures and antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Solanki, Ankita; Sadhu, Mehul H.; Kumar, Sujit Baran

    2015-12-01

    Five new mononuclear mixed ligand complexes of the type [Cu(NCCH3)(dbdmp)](ClO4)2, [M(ONO)(dbdmp)]ClO4, [M(pz) (dbdmp)](ClO4)2 where M = Cu(II) and Co(II), pz = 3,5-dimethylpyrazole and dbdmp = N,N-diethyl-N‧,N‧-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine have been synthesized and characterized by physico-chemical and spectroscopy studies. The crystal structures of three copper(II) complexes [Cu(NCCH3)(dbdmp)](ClO4)2, [Cu(ONO)(dbdmp)]ClO4 and [Cu(pz)(dbdmp)](ClO4)2 have been determined by single crystal X-ray diffraction studies. Structural analyses reveal the geometry of [Cu(pz)(dbdmp)](ClO4)2 is distorted square pyramidal and other two copper(II) complexes have distorted trigonal bipyramidal geometry. Molecular composition of cobalt(II) complexes have been determined by mass spectral data. The EPR spectra of copper(II) complexes in frozen acetonitrile solution exhibit axial spectra, characteristic of dx2-y2 ground state. Electrochemical studies of copper(II) complexes using glassy carbon as working electrode in acetonitrile solution show Cu(II)/Cu(I) couple with quasi reversible electron transfer versus Ag/Ag+ reference electrode. Antimicrobial activity of all the synthesized complexes were investigated against two Gram positive and two Gram negative bacterial strains.

  13. Ferromagnetic coupling and magnetic anisotropy in oxalato-bridged trinuclear chromium(III)-cobalt(II) complexes with aromatic diimine ligands.

    PubMed

    Vallejo, Julia; Castro, Isabel; Cañadillas-Delgado, Laura; Ruiz-Pérez, Catalina; Ferrando-Soria, Jesús; Ruiz-García, Rafael; Cano, Joan; Lloret, Francesc; Julve, Miguel

    2010-03-07

    Two novel heterotrinuclear chromium(III)-cobalt(II) complexes of formula {[Cr(III)(bpy)(ox)(2)](2)Co(II)(Me(2)bpy)}.2H(2)O (1) and {[Cr(III)(phen)(ox)(2)](2)Co(II)(Me(2)bpy)}.1.5H(2)O (2) [ox = oxalato, bpy = 2,2'-bipyridine, Me(2)bpy = 6,6'-dimethyl-2,2'-bipyridine, and phen = 1,10-phenanthroline] have been synthesized using the "complex-as-ligand/complex-as-metal" strategy. The X-ray crystal structure of 2 consists of neutral oxalato-bridged Cr(III)(2)Co(II) bent entities formed by the coordination of two anionic [Cr(III)(phen)(ox)(2)](-) complexes through one of their oxalato groups toward a cationic cis-[Co(II)(Me(2)bpy)](2+) complex. The three tris(chelated), six-coordinated metal atoms possess alternating propeller chiralities leading thus to a racemic mixture of heterochiral (Lambda,Delta,Lambda)- and (Delta,Lambda,Delta)-Cr(III)Co(II)Cr(III) triads, whereby the two peripheral chromium(III) ions adopt a trigonal distorted trapezoidal bipyramidal geometry and the central high-spin cobalt(II) ion exhibits a compressed rectangular bipyramidal one. The intermolecular pi-pi stacking interactions between the enantiomeric pairs of heterochiral Cr(III)(2)Co(II) entities through the aromatic diimine terminal ligands lead to a unique two-dimensional supramolecular network. Variable temperature (2.0-300 K) magnetic susceptibility and variable-field (0-5.0 T) magnetization measurements for 1 and 2 reveal the presence of weak but non-negligible intermolecular antiferromagnetic interactions [zj = -0.012 (2a) and -0.08 cm(-1) (2b)] between the Cr(III)(2)Co(II) molecules possessing a moderately anisotropic S = 9/2 ground state. This results from the moderately weak intramolecular ferromagnetic coupling [J = +2.43 (1) and +2.34 cm(-1) (2)] between the two peripheral Cr(III) (S(Cr) = 3/2) and the central high-spin Co(II) (S(Co) = 3/2) ions across the oxalato bridge as well as the appreciable single-ion axial magnetic anisotropy of the central high-spin Co(II) (S(Co) = 3

  14. Characterization of the Unusual Product from the Reaction between Cobalt(II) Chloride, Ethane-1,2-diamine, and Hydrochloric Acid: An Undergraduate Project Involving an Unknown Metal Complex.

    ERIC Educational Resources Information Center

    Curtis, Neil F.; And Others

    1986-01-01

    Discusses the need for student research-type chemistry projects based upon "unknown" metal complexes. Describes an experiment involving the product from the reaction between cobalt(II) chloride, ethane-1,2-diamine (en) and concentrated hydrochloric acid. Outlines the preparation of the cobalt complex, along with procedure, results and…

  15. Cobalt(II), nickel(II) and copper(II) complexes of a hexadentate pyridine amide ligand. Effect of donor atom (ether vs. thioether) on coordination geometry, spin-state of cobalt and M(III)-M(II) redox potential.

    PubMed

    Pandey, Sharmila; Das, Partha Pratim; Singh, Akhilesh Kumar; Mukherjee, Rabindranath

    2011-10-28

    Using an acyclic hexadentate pyridine amide ligand, containing a -OCH(2)CH(2)O- spacer between two pyridine-2-carboxamide units (1,4-bis[o-(pyrydine-2-carboxamidophenyl)]-1,4-dioxabutane (H(2)L(9)), in its deprotonated form), four new complexes, [Co(II)(L(9))] (1) and its one-electron oxidized counterpart [Co(III)(L(9))][NO(3)]·2H(2)O (2), [Ni(II)(L(9))] (3) and [Cu(II)(L(9))] (4), have been synthesized. Structural analyses revealed that the Co(II) centre in 1 and the Ni(II) centre in 3 are six-coordinate, utilizing all the available donor sites and the Cu(II) centre in 4 is effectively five-coordinated (one of the ether O atoms does not participate in coordination). The structural parameters associated with the change in the metal coordination environment have been compared with corresponding complexes of thioether-containing hexadentate ligands. The μ(eff) values at 298 K of 1-4 correspond to S = 3/2, S = 0, S = 1 and S = 1/2, respectively. Absorption spectra for all the complexes have been investigated. EPR spectral properties of the copper(II) complex 4 have been investigated, simulated and analyzed. Cyclic voltammetric experiments in CH(2)Cl(2) reveal quasireversible Co(III)-Co(II), Ni(III)-Ni(II) and Cu(II)-Cu(I) redox processes. In going from ether O to thioether S coordination, the effect of the metal coordination environment on the redox potential values of Co(III)-Co(II) (here the effect of spin-state as well), Ni(III)-Ni(II) and Cu(II)-Cu(I) processes have been systematically analyzed.

  16. Differential diagnosis of CT-hypodense cranial lesions with indium-111-oxine-labeled leukocytes

    SciTech Connect

    Bellotti, C.; Aragno, M.G.; Medina, M.; Viglietti, A.L.; Oliveri, G.; Ettorre, F.; Barrale, S.; Camuzzini, G.

    1986-05-01

    Scintigraphy using indium-111-oxine-labeled white blood cells was used as a complementary diagnostic study in the differential diagnosis of 20 intracerebral cystic lesions for which computerized tomography scanning did not exclude abscess. To lower the rate of false-positive findings with scintiscanning, three criteria of positivity were tested in the 20 lesions. The most stringent criterion yielded 100% sensitivity, 94% specificity, and 96% diagnostic accuracy. The clinical and surgical implications of these results are discussed.

  17. Diaquatetrakis(tert-butyl isocyanide)cobalt(II) bis(perchlorate): an example of cobalt(II) coordinated by only four alkyl isocyanide ligands.

    PubMed

    Becker, Clifford A L; Forbes, Roy P; Black, Robert S

    2009-08-01

    The title compound, [Co(C5H9N)4(H2O)2](ClO4)2, crystallizes in the monoclinic space group C2/m. The cation has space-group-imposed 2/m symmetry, while the perchlorate ion is disordered about a mirror plane. The two slightly non-equivalent Co-C bonds [1.900 (3) and 1.911 (3) A] form a rectangular plane, with a C-Co-C bond angle of 86.83 (11) degrees, and the linear O-Co-O C2 axis is perpendicular to this plane. The C[triple-bond]N bond lengths are 1.141 (4) A and the Co-C[triple-bond]N and C[triple-bond]N-C angles average 175.5 (4) degrees. The perchlorate counter-ions are hydrogen bonded to the water molecules. The title compound is the first example of four alkyl isocyanide ligands coordinating Co(II) upon initial reaction of Co(ClO4)(2).6H2O/EtOH with alkyl isocyanide. In all other known examples, five alkyl isocyanide molecules are coordinated, as in [(RNC)5Co-Co(CNR)5](ClO4)4 (R = Me, Et, CHMe2, CH2Ph, C4H9-n or C6H11) or [Co(CNC8H17-t)5](ClO4)2. This complex, therefore, is unique and somewhat unexpected.

  18. Antibacterial cobalt (II), copper (II), nickel (II) and zinc (II) complexes of mercaptothiadiazole--derived furanyl, thienyl, pyrrolyl, salicylyl and pyridinyl Schiff bases.

    PubMed

    Chohan, Zahid H; Pervez, Humayun; Rauf, Abdul; Khan, Khalid M; Supuran, Claudiu T

    2006-04-01

    A series of Co (II), Cu (II), Ni (II) and Zn (II) complexes of mercaptothiadiazole-derived furanyl, thienyl, pyrrorlyl, salicylyl and pyridinyl Schiff bases were synthesized, characterized and screened for their in vitro antibacterial activity against four Gram-negative, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Shigella fexneri, and two Gram-positive; Bacillus subtilis and Staphylococcus aureous bacterial strains. The results of these studies show the metal complexes to be more antibacterial as compared to the prepared un-complexed Schiff bases.

  19. 89Zr-Oxine Complex PET Cell Imaging in Monitoring Cell-based Therapies

    PubMed Central

    Wu, Haitao; Asiedu, Kingsley O.; Szajek, Lawrence P.; Griffiths, Gary L.; Choyke, Peter L.

    2015-01-01

    Purpose To develop a clinically translatable method of cell labeling with zirconium 89 (89Zr) and oxine to track cells with positron emission tomography (PET) in mouse models of cell-based therapy. Materials and Methods This study was approved by the institutional animal care committee. 89Zr-oxine complex was synthesized in an aqueous solution. Cell labeling conditions were optimized by using EL4 mouse lymphoma cells, and labeling efficiency was examined by using dendritic cells (DCs) (n = 4), naïve (n = 3) and activated (n = 3) cytotoxic T cells (CTLs), and natural killer (NK) (n = 4), bone marrow (n = 4), and EL4 (n = 4) cells. The effect of 89Zr labeling on cell survival, proliferation, and function were evaluated by using DCs (n = 3) and CTLs (n = 3). Labeled DCs (444–555 kBq/[5 × 106] cells, n = 5) and CTLs (185 kBq/[5 × 106] cells, n = 3) transferred to mice were tracked with microPET/CT. In a melanoma immunotherapy model, tumor targeting and cytotoxic function of labeled CTLs were evaluated with imaging (248.5 kBq/[7.7 × 106] cells, n = 4) and by measuring the tumor size (n = 6). Two-way analysis of variance was used to compare labeling conditions, the Wilcoxon test was used to assess cell survival and proliferation, and Holm-Sidak multiple tests were used to assess tumor growth and perform biodistribution analyses. Results 89Zr-oxine complex was synthesized at a mean yield of 97.3% ± 2.8 (standard deviation). It readily labeled cells at room temperature or 4°C in phosphate-buffered saline (labeling efficiency range, 13.0%–43.9%) and was stably retained (83.5% ± 1.8 retention on day 5 in DCs). Labeling did not affect the viability of DCs and CTLs when compared with nonlabeled control mice (P > .05), nor did it affect functionality. 89Zr-oxine complex enabled extended cell tracking for 7 days. Labeled tumor-specific CTLs accumulated in the tumor (4.6% on day 7) and induced tumor regression (P < .05 on day 7). Conclusion We have developed a 89Zr-oxine

  20. Synthesis, characterization, and catalytic properties of cationic hydrogels containing copper(II) and cobalt(II) ions.

    PubMed

    Lombardo Lupano, Lucía Victoria; Lázaro Martínez, Juan Manuel; Piehl, Lidia Leonor; Rubín de Celis, Emilio; Torres Sánchez, Rosa María; Campo Dall' Orto, Viviana

    2014-03-18

    Here, we report the synthesis and characterization of a hydrogel based on ethylene glycol diglycidyl ether (EGDE) and 1,8-diamino-3,6-dioxaoctane (DA). Chemically stable Co(II) and Cu(II) coordination complexes were prepared with this nonsoluble polyelectrolyte, poly(EGDE-DA), and studied by ss-NMR, FT-IR, thermogravimetry, and microscopy. Mesopores were found in all the samples, the thermal stability of the polymer matrix was highly affected by the presence of metal ions, and the (13)C CP-MAS spectrum for the Cu(II)-complex evidenced a significant increase in the reticulation degree by Cu(II) ions. The catalytic activity of these materials on H2O2 activation was studied by electron spin resonance (ESR). The Co(II)-poly(EGDE-DA)/H2O2 heterogeneous system produced O2, an anion superoxide (O2(•)¯), and a hydroxyl radical (OH(•)), which diffused into the solution at the time that a decrease in pH was detected. In the same way, the Cu(II)-poly(EGDE-DA)/H2O2 heterogeneous system produced O2 and OH(•). H2O2 activation by the poly(EGDE-DA) complexes with Co(II) and Cu(II) were applied on the decolorization of solutions of the azo-dye methyl orange (MO). In the presence of 63 mM H2O2, 87% of MO was removed in 10 min with Cu(II)-poly(EGDE-DA) and in 110 min with Co(II)-poly(EGDE-DA). In addition, the pharmaceutical product epinephrine was partially oxidized to adrenochrome by the O2(•)¯ released from the Co(II)-poly(EGDE-DA)/H2O2 heterogeneous system.

  1. Cobalt(II), nickel(II), copper(II), zinc(II) and hafnium(IV) complexes of N'-(furan-3-ylmethylene)-2-(4-methoxyphenylamino)acetohydrazide.

    PubMed

    Emam, Sanaa M; El-Saied, Fathy A; Abou El-Enein, Saeyda A; El-Shater, Heba A

    2009-03-01

    Cobalt(II), nickel(II), copper(II), zinc(II) and hafnium(IV) complexes of furan-2-carbaldehyde 4-methoxy-N-anilinoacetohydrazone were synthesized and characterized by elemental and thermal (TG and DTA) analyses, IR, UV-vis and (1)H NMR spectra as well as magnetic moment and molar conductivity. Mononuclear complexes are obtained with 1:1 molar ratio except complexes 3 and 9 which are obtained with 1:2 molar ratios. The IR spectra of ligand and metal complexes reveal various modes of chelation. The ligand behaves as a neutral bidentate one and coordination occurs via the carbonyl oxygen atom and azomethine nitrogen atom. The ligand behaves also as a monobasic tridentate one and coordination occurs through the enolic oxygen atom, azomethine nitrogen atom and the oxygen atom of furan ring. Moreover, the ligand behaves as a neutral tridentate and coordination occurs via the carbonyl oxygen, azomethine nitrogen and furan oxygen atoms as well as a monobasic bidentate and coordination occurs via the enolic oxygen atom and azomethine nitrogen atom. The electronic spectra and magnetic moment measurements reveal that all complexes possess octahedral geometry except the copper complex 10 possesses a square planar geometry. The thermal studies showed the type of water molecules involved in metal complexes as well as the thermal decomposition of some metal complexes.

  2. Coordination modes of a schiff base pentadentate derivative of 4-aminoantipyrine with cobalt(II), nickel(II) and copper(II) metal ions: synthesis, spectroscopic and antimicrobial studies.

    PubMed

    Chandra, Sulekh; Jain, Deepali; Sharma, Amit Kumar; Sharma, Pratibha

    2009-01-01

    Transition metal complexes of Co(II), Ni(II) and Cu(II) metal ions with general stoichiometry [M(L)X]X and [M(L)SO(4)], where M = Co(II), Ni(II) and Cu(II), L = 3,3'-thiodipropionic acid bis(4-amino-5-ethylimino-2,3-dimethyl-1-phenyl-3-pyrazoline) and X = NO(3)(-), Cl(-) and OAc(-), have been synthesized and structurally characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements and spectral techniques like IR, UV and EPR. The nickel(II) complexes were found to have octahedral geometry, whereas cobalt(II) and copper(II) complexes were of tetragonal geometry. The covalency factor (beta) and orbital reduction factor (k) suggest the covalent nature of the complexes. The ligand and its complexes have been screened for their antifungal and antibacterial activities against three fungi, i.e. Alternaria brassicae, Aspergillus niger and Fusarium oxysporum and two bacteria, i.e. Xanthomonas compestris and Pseudomonas aeruginosa.

  3. Dichloridobis[2-methyl-sulfanyl-4-(pyridin-2-yl)pyrimidine-κN,N]cobalt(II).

    PubMed

    Yang, Wen-Na

    2011-09-01

    The asymmetric unit of the title compound, [CoCl(2)(C(10)H(9)N(3)S)(2)], contains one half-mol-ecule with the Co(II) atom situtated on a twofold rotational axis. The Co(II) atom, in an octa-hedral enviroment, is coordinated by four N atoms from two 2-methyl-sulfanyl-4-(pyridin-2-yl)pyrimidine ligands and two Cl atoms.

  4. Metalloantibiotics: synthesis, characterization and in-vitro antibacterial studies on cobalt (II), copper (II), nickel (II) and zinc (II) complexes with cloxacillin.

    PubMed

    Chohan, Zahid H; Supuran, Claudiu T

    2006-08-01

    The synthesis and characterization of cloxacillin (clox) complexes with divalent metal ions [Co (II), Cu (II), Ni (II) and Zn (II)] is described. The nature of bonding of the chelated cloxacillin and the structures of the metal complexes have been elucidated on the basis of their physical and spectroscopic data. In all the complexes, the cloxacillin acts as a uninegatively charged bidentate ligand with coordination involving the carboxylate-O and endocyclic-N of the beta-lactam ring. The new compounds have been screened for in-vitro antibacterial activity against Escherichia coli (a), Klebsiella pneumonae (b), Proteus mirabilis (c), Pseudomonas aeruginosa (d), Salmonella typhi (e), Shigella dysentriae (f), Bacillus cereus (g), Corynebacterium diphtheriae (h), Staphylococcus aureus (j) and Streptococcus pyogenes (k) bacterial strains. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties. All compounds, respectively, showed a promising activity (90%) against five bacterial species at 10 microg/ml concentration and a significant activity (52%) against the same test bacteria at 25 microg/ml concentration.

  5. Solvent effects of N-nitroso, N-(2-chloroethyl), N',N'-dibenzylsulfamid and its copper(II) and cobalt(II) complexes: fluorescence studies.

    PubMed

    Bensouilah, Nadjia; Fisli, Hassina; Dhaoui, Nabila; Benali-Cherif, Nourredine; Abdaoui, Mohamed

    2013-01-01

    The structure of N-nitroso, N-(2-chloroethyl), N',N'-dibenzylsulfamid (CENS) was established by X-ray crystallography. The atomic coordinates, factors of isotropic thermal agitation, bond lengths and valence angles were determined. The solvent effects on the electronic absorption and fluorescence spectra of CENS were investigated at room temperature. The effects of solvent polarity and of hydrogen bonding were interpreted by means of linear solvation energy relationships (LSERs). Multiple linear regression analysis indicated that the hydrogen donation properties of the solvent play an important role in determining the position of the absorption maximum, while the classical polarity of the medium is the only dominating parameter in determining the emission maximum and the Stokes' shift. Complexation of the investigated compound by two different transition metal ions was studied. Fluorescence measurements show that fluorescence quenching by cobalt(II) is more important than that by copper(II). This phenomenon can be attributed to good stereo-structural matching between the electronic configuration of the Co(2+) ion and the active site distribution of CENS in aqueous solution.

  6. Corroborative models of the cobalt(II) inhibited Fe/Mn superoxide dismutases.

    PubMed

    Scarpellini, Marciela; Wu, Amy J; Kampf, Jeff W; Pecoraro, Vincent L

    2005-07-11

    Attempting to model superoxide dismutase (SOD) enzymes, we designed two new N3O-donor ligands to provide the same set of donor atoms observed in the active site of these enzymes: K(i)Pr2TCMA (potassium 1,4-diisopropyl-1,4,7-triazacyclononane-N-acetate) and KBPZG (potassium N,N-bis(3,5-dimethylpyrazolylmethyl) glycinate). Five new Co(II) complexes (1-5) were obtained and characterized by X-ray crystallography, mass spectrometry, electrochemistry, magnetochemistry, UV-vis, and electron paramagnetic resonance (EPR) spectroscopies. The crystal structures of 1 and 3-5 revealed five-coordinate complexes, whereas complex 2 is six-coordinate. The EPR data of complexes 3 and 4 agree with those of the Co(II)-substituted SOD, which strongly support the proposition that the active site of the enzyme structurally resembles these models. The redox behavior of complexes 1-5 clearly demonstrates the stabilization of the Co(II) state in the ligand field provided by these ligands. The irreversibility displayed by all of the complexes is probably related to an electron-transfer process followed by a rearrangement of the geometry around the metal center for complexes 1 and 3-5 that probably changes from a trigonal bipyramidal (high spin, d7) to octahedral (low spin, d6) as Co(II) is oxidized to Co(III), which is also expected to be accompanied by a spin-state conversion. As the redox potentials to convert the Co(II) to Co(III) are high, it can be inferred that the redox potential of the Co(II)-substituted SOD may be outside the range required to convert the superoxide radical (O2*-) to hydrogen peroxide, and this is sufficient to explain the inactivity of the enzyme. Finally, the complexes reported here are the first corroborative structural models of the Co(II)-substituted SOD.

  7. Lutein Attenuates Both Apoptosis and Autophagy upon Cobalt (II) Chloride-Induced Hypoxia in Rat Műller Cells

    PubMed Central

    Fung, Frederic K. C.; Law, Betty Y. K.; Lo, Amy C. Y.

    2016-01-01

    Retinal ischemia/reperfusion injury is a common feature of various retinal diseases such as glaucoma and diabetic retinopathy. Lutein, a potent anti-oxidant, is used to improve visual function in patients with age-related macular degeneration (AMD). Lutein attenuates apoptosis, oxidative stress and inflammation in animal models of acute retinal ischemia/hypoxia. Here, we further show that lutein improved Műller cell viability and enhanced cell survival upon hypoxia-induced cell death through regulation of intrinsic apoptotic pathway. Moreover, autophagy was activated upon treatment of cobalt (II) chloride, indicating that hypoxic injury not only triggered apoptosis but also autophagy in our in vitro model. Most importantly, we report for the first time that lutein treatment suppressed autophagosome formation after hypoxic insult and lutein administration could inhibit autophagic event after activation of autophagy by a pharmacological approach (rapamycin). Taken together, lutein may have a beneficial role in enhancing glial cell survival after hypoxic injury through regulating both apoptosis and autophagy. PMID:27936094

  8. Ring-opening of unsymmetrical 1,2-dioxines using cobalt(II) salen complexes.

    PubMed

    Greatrex, Ben W; Taylor, Dennis K

    2005-01-21

    The regioselectivity of the metal-catalyzed ring opening of unsymmetrical 1,2-dioxines to cis-gamma-hydroxyenones was investigated using two different Co(II) salen complexes. Regioselectivity was determined by direct examination of the enone ratios and by derivitization with a stabilized phosphorus ylide. The steric influence of the substituents on the 1,2-dioxine was the primary influence on regioselectivity. Temperature played little role; however, solvent and selection of Co(II) complex could be used to mildly influence the outcome of the rearrangement for selected substrates. The origins of the selectivity for the reaction are discussed.

  9. Kagóme Cobalt(II)-Organic Layers as Robust Scaffolds for Highly Efficient Photocatalytic Oxygen Evolution.

    PubMed

    Xu, Jiaheng; Wang, Zhi; Yu, Wenguang; Sun, Di; Zhang, Qing; Tung, Chen-Ho; Wang, Wenguang

    2016-05-23

    Two Kagóme cobalt(II)-organic layers of [Co3 (μ3 -OH)2 (bdc)2 ]n (1) and [Co3 (μ3 -OH)2 (chdc)2 ]n (2) (bdc=o-benzenedicarboxylate and chdc=1,2-cyclohexanedicarboxylate) that bear bridging OH(-) ligands were explored as water oxidation catalysts (WOCs) for photocatalytic O2 production. The activities of 1 and 2 towards H2 O oxidation were assessed by monitoring the in situ O2 concentration versus time in the reaction medium by utilizing a Clark-type oxygen electrode under photochemical conditions. The oxygen evolution rate (RO2 ) was 24.3 μmol s(-1)  g(-1) for 1 and 48.8 μmol s(-1)  g(-1) for 2 at pH 8.0. Photocatalytic reaction studies show that 1 and 2 exhibit enhanced activities toward the oxidation of water compared to commercial nanosized Co3 O4 . In scaled-up photoreactions, the pH value of the reaction medium decreased from 8.0 to around 7.0 after 20 min and the O2 production ceased. Based on the amounts of the sacrificial oxidant (K2 S2 O8 ) used, the yield of O2 produced is 49.6 % for 2 and 29.8 % for 1. However, the catalyst can be recycled without a significant loss of catalytic activity. Spectroscopic studies suggest that the structure and composition of recycled 1 and 2 are maintained. In isotope-labeling H2 (18) O (97 % enriched) experiments, the distribution of (16) O(16) O/(16) O(18) O/(18) O(18) O detected was 0:7.55:92.45, which is comparable to the theoretical values of 0.09:5.82:94.09. This work not only provides new catalysts that resemble ligand-protected cobalt oxide materials but also establishes the significance of the existence of OH(-) (or H2 O) binding sites at the metal center in WOCs.

  10. Reversible Oxygenation of α-Amino Acid–Cobalt(II) Complexes

    PubMed Central

    Zhang, Xincun; Yue, Fan; Li, Hui; Huang, Yan; Zhang, Yi; Wen, Hongmei; Wang, Jide

    2016-01-01

    We systematically investigated the reversibility, time lapse, and oxygenation-deoxygenation properties of 15 natural α-amino acid–Co(II) complexes through UV-vis spectrophotometer, polarographic oxygen electrode, and DFT calculations, respectively, to explore the relationship between the coordinating structure and reversible oxygenation of α-amino acid–Co(II) complexes. Results revealed that the α-amino acid structure plays a key role in the reversible oxygenation properties of these complexes. The specific configuration of the α-amino acid group affects the eg1 electron of Co(II) transfer to the π⁎ orbit of O2; this phenomenon also favors the reversible formation and dissociation of Co–O2 bond when O2 coordinates with Co(II) complexes. Therefore, the co-coordination of amino and carboxyl groups is a determinant of Co complexes to absorb O2 reversibly. The group adjacent to the α-amino acid unit evidently influences the dioxygen affinity and antioxidation ability of the complexes. The presence of amino (or imino) and hydroxy groups adjacent to the α-amino acid group increases the oxygenation-deoxygenation rate and the number of reversible cycles. Our findings demonstrate a new mechanism to develop reversible oxygenation complexes and to reveal the oxygenation of oxygen carriers. PMID:27022316

  11. Tc-99m hexamethylpropylene-amine oxine (HM-PAO) uptake in a bone metastasis

    SciTech Connect

    Hoshi, H.; Jinnouchi, S.; Sameshima, M.; Uwada, O.; Watanabe, K.

    1988-08-01

    Uptake of Tc-99m Hexamethylpropylene-amine Oxine (HM-PAO) was seen in bone metastases from carcinoma of the lung. The uptake was prominent when compared to Tc-99m MDP, I-123 IMP, and Ga-67 citrate. Brain imaging with Tc-99m HM-PAO and N-isopropyl-p-(I-123) iodoamphetamine (IMP) is now frequently performed. Uptake of these agents has been reported in brain tumors and melanomas. In this report, uptake of Tc-99m HM-PAO in a metastatic lesion in bone is discussed.

  12. Mechanistic aspects of the quenching of triplet methylene blue by complexes of cobalt(II)

    SciTech Connect

    Ohno, T.; Lichtin, N.N.

    1980-11-13

    A Q-switched ruby laser emitting 1.0-J flashes at 693.4 nm was used in a flash-photolytic, kinetic-spectrometric investigation of the mechanism of quenching of 10 ..mu..M triplet methylene blue by Co/sup II/(edta)/sup 2 -/, Co/sup II/(TIM)(H/sub 2/O)/sub 2//sup 2 +/, Co/sup II/(phen)/sub 3//sup 2 +/, and Co/sup II/(tpy)/sub 2//sup 2 +/ (edta = ethylenediamine-N,N-N',N'-tetraacetic acid; TIM = 1,4,8,11-tetraaza-2,3-dimethylcyclotetradeca-1,3,8,10-tetraene; phen = 1,10-phenanthroline; and tpy = 2,2',2''-terpyridine) in water and aqueous EtOH at pH approx. 2 and approx. 6, where the species quenched and the product of its reductive quenching are, respectively, /sup 3/MBH/sup 2 +/ and MBH/sup +/. Specific rates of quenching, k/sub q/, of net electron transfer during quenching, k/sub et/, and the kinetics of decay of the products of quenching were determined. Specific rates, k/sub ret/, of reverse electron transfer from MBH/sup +/. to complexes of Co(III), Co/sup III/L/sub x//sup m+1/, were evaluated by generating MBH/sup +/. by quenching /sup 3/MBH/sup 2 +/ with diphenylamine in the presence of Co/sup III/L/sub x//sup m+1/. Values of F/sub 1/ = k/sub et//k/sub q/, of F/sub 2/ = k/sub ret//k/sub D/, where k/sub D/ is the diffusion-controlled specific rate of encounter, and of F/sub 1/ + F/sub 2/ are compared with analogous data for quenching of /sup 3/MBH/sup 2 +/ by complexes of Fe(II) and with the detailed reversible electron-transfer model which was developed for the latter processes. It is concluded that reversible electron transfer is not the only significant mechanism of quenching of /sup 3/MBH/sup 2 +/ by the four complexes of Co(II) employed in this research. At least one other mechanism, e.g., energy transfer or physical quenching, is followed to a significant degree.

  13. Formation of a cobalt(III)-phenoxyl radical complex by acetic acid promoted aerobic oxidation of a Co(II)salen complex.

    PubMed

    Vinck, Evi; Murphy, Damien M; Fallis, Ian A; Strevens, Robert R; Van Doorslaer, Sabine

    2010-03-01

    The activation of N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamino Co(II), [Co(II)(1)], by the addition of acetic acid under aerobic conditions has been investigated by a range of spectroscopic techniques including continuous-wave EPR, HYSCORE, pulsed ENDOR, and resonance Raman. These measurements have revealed for the first time the formation of a coordinated cobalt(III)-bound phenoxyl radical labeled [Co(III)(1(*))(OAc)(n)](OAc)(m) (n = m = 1 or n = 2, m = 0). This cobalt(III)-bound phenoxyl radical is characterized by the following spin Hamiltonian parameters: g(x) = 2.0060, g(y) = 2.0031, g(z) = 1.9943, A(x) = 17 MHz, A(y) = 55 MHz, and A(z) = 14 MHz. Although the radical contains coordinated acetate(s), the experiments unambiguously proved that the phenoxyl radical is situated on ligand (1) as opposed to a phenoxyl radical ligated to cobalt in the axial position. Density functional theory computations on different models corroborate the stability of such a phenoxyl radical species and suggest the ligation of one or two acetate molecules to the complex. A mechanism is proposed, which accounts for the formation of this unusual and extremely robust phenoxyl radical, never previously observed for [Co(1)].

  14. Chemical modification of silica gel with synthesized new Schiff base derivatives and sorption studies of cobalt (II) and nickel (II)

    NASA Astrophysics Data System (ADS)

    Kursunlu, Ahmed Nuri; Guler, Ersin; Dumrul, Hakan; Kocyigit, Ozcan; Gubbuk, Ilkay Hilal

    2009-08-01

    In this study, three Schiff base ligands and their complexes were synthesized and characterized by infrared spectroscopy (IR), thermogravimetric analyses (TGA), nuclear magnetic resonance (NMR), elemental analysis and magnetic susceptibility apparatuses. Silica gel was respectively modified with Schiff base derivatives, (E)-2-[(2-chloroethylimino)methyl]phenol, (E)-4-[(2-chloroethylimino)methyl]phenol and N, N'-[1,4-phenilendi(E)methylidene]bis(2-chloroethanamine), after silanization of silica gel by (3-aminopropyl)trimethoxysilane (APTS) by using a suitable method. Characterization of the surface modification was also performed with IR, TGA and elemental analysis. The immobilized surfaces were used for Co(II) and Ni(II) sorption from aqueous solutions and values of sorption were detected by atomic absorption spectrometer (AAS).

  15. Physicochemical and biological properties of oxovanadium(IV), cobalt(II) and nickel(II) complexes with oxydiacetate anions.

    PubMed

    Wyrzykowski, Dariusz; Kloska, Anna; Pranczk, Joanna; Szczepańska, Aneta; Tesmar, Aleksandra; Jacewicz, Dagmara; Pilarski, Bogusław; Chmurzyński, Lech

    2015-03-01

    The potentiometric and conductometric titration methods have been used to characterize the stability of series of VO(IV)-, Co(II)- and Ni(II)-oxydiacetato complexes in DMSO-water solutions containing 0-50 % (v/v) DMSO. The influence of DMSO as a co-solvent on the stability of the complexes as well as the oxydiacetic acid was evaluated. Furthermore, the reactivity of the complexes towards superoxide free radicals was assessed by employing the nitro blue tetrazolium (NBT) assay. The biological properties of the complexes were investigated in relation to their cytoprotective activity against the oxidative damage generated exogenously by using hydrogen peroxide in the Human Dermal Fibroblasts adult (HDFa) cell line as well as to their antimicrobial activity against the bacteria (Bacillus subtilis, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis). The relationship between physicochemical and biological properties of the complexes was discussed.

  16. Diaqua­bis­(hydrogen tartrato)cobalt(II) dihydrate

    PubMed Central

    Du, Chao-Jun; Zhang, Qun-An; Wang, Li-Sheng; Du, Chao-Ling

    2012-01-01

    The title complex, [Co(C4H5O6)2(H2O)2]·2H2O, contains a CoII ion, two single deprotonated tartrate anions, two coordinated water mol­ecules and two lattice water mol­ecules. The coordination geometry of the CoII ion is a distorted octa­hedron with two O atoms from two coordinated water mol­ecules occupying cis positions in the equatorial plane and four O atoms from two hydrogen tartrate ions occupying the remaining positions. In the crystal, inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional network. PMID:22346896

  17. Radical polymerization of vinyl acetate with bis(tetramethylheptadionato)cobalt(II): coexistence of three different mechanisms.

    PubMed

    Santhosh, Kumar; Gnanou, Yves; Champouret, Yohan; Daran, Jean-Claude; Poli, Rinaldo

    2009-01-01

    The complex [Co(II)(tmhd)(2)] (4; tmhd = 2,2,6,6-tetramethylhepta-3,5-dionato) has been investigated as a mediator for controlled radical polymerization of vinyl acetate (VAc) and compared with the analogue [Co(II)(acac)(2)] (1; acac = acetylacetonato). A relatively well controlled process occurs, after an induction time, with 2,2'-azobis(4-methoxyl-2,4-dimethylvaleronitrile) (V-70) as radical initiator at 30 degrees C. However, whereas the polymerization essentially stops after about six initiator half-lives in the presence of 1, it continues with a first-order rate law in the presence of 4. The successful simulation of the kinetic data shows that 4 operates simultaneously by associative (degenerative transfer, DT) and dissociative (organometallic radical polymerization, OMRP) mechanisms. The occurrence of OMRP was confirmed by an independent polymerization experiment starting from an isolated and purified [Co(tmhd)(2)](PVAc) macroinitiator. The polymer molecular weight evolves linearly with conversion in accordance with the expected values for one chain per Co atom when DT is the predominant mechanism and also during the pure OMRP process; however, observation of stagnating molecular weights at long reaction times with concomitant breakdown of the first-order rate law for monomer consumption indicates a competitive chain-transfer process catalyzed by an increasing amount of Co(II). In the presence of external donors L (water, pyridine, triethylamine) the DT pathway is blocked and the OMRP pathway is accelerated, and polymerization with complex 4 is then about five times slower than with complex 1. The reversal of relative effective OMRP rate constants k(eff) (4>1 in the absence of external donors, 4<1 in their presence) is rationalized through competitive steric effects on Co(III)-C and Co(II)-L bond strengths. These propositions are supported by (1)H NMR studies and by DFT calculations.

  18. Cobalt(II) complexes with bis(N-imidazolyl/benzimidazolyl) pyridazine: Structures, photoluminescent and photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Li, Jin-Ping; Fan, Jian-Zhong; Wang, Duo-Zhi

    2016-07-01

    Six new CoII complexes [Co(L1)4(OH)2] (1), {[Co(L1)(H2O)4]·2ClO4}∞ (2), {[Co(L1)(H2O)4]·SiF6}∞ (3), {[Co(L1)3]·2ClO4}∞ (4), [Co(L2)Cl2]∞ (5) and {[Co(L2)2]·SiF6}∞ (6) [L1=3,6-bis(N-imidazolyl) pyridazine, L2=3,6-bis (N-benzimidazolyl) pyridazine] have been synthesized and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. Complex 1 has a mononuclear structure, while complexes 2 and 3 have 1-D chain structures. Considering the CoII centers were linked by the L1 ligands, the 3-D framework of complex 4 can be rationalized to be a {4^12.6^3} 6-c topological net with the stoichiometry uninodal net. 5 reveals a coordination 1-D zigzag chain structure consisting of a neutral chain [Co(L2)Cl2]n with the CoII centers. Complex 6 has a rhombohedral grid with a (4, 4) topology. The TGA property, fluorescent property and photocatalytic activity of complexes 1-6 have been investigated and discussed.

  19. Cobalt(II) complexes with bis(N-imidazolyl/benzimidazolyl) pyridazine: Structures, photoluminescent and photocatalytic properties

    SciTech Connect

    Li, Jin-Ping; Fan, Jian-Zhong; Wang, Duo-Zhi

    2016-07-15

    Six new Co{sup II} complexes [Co(L{sup 1}){sub 4}(OH){sub 2}] (1), {[Co(L"1)(H_2O)_4]·2ClO_4}{sub ∞} (2), {[Co(L"1)(H_2O)_4]·SiF_6}{sub ∞} (3), {[Co(L"1)_3]·2ClO_4}{sub ∞} (4), [Co(L{sup 2})Cl{sub 2}]{sub ∞} (5) and {[Co(L"2)_2]·SiF_6}{sub ∞} (6) [L{sup 1}=3,6-bis(N-imidazolyl) pyridazine, L{sup 2}=3,6-bis (N-benzimidazolyl) pyridazine] have been synthesized and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. Complex 1 has a mononuclear structure, while complexes 2 and 3 have 1-D chain structures. Considering the Co{sup II} centers were linked by the L{sup 1} ligands, the 3-D framework of complex 4 can be rationalized to be a {4^12.6^3} 6-c topological net with the stoichiometry uninodal net. 5 reveals a coordination 1-D zigzag chain structure consisting of a neutral chain [Co(L{sup 2})Cl{sub 2}]{sub n} with the Co{sup II} centers. Complex 6 has a rhombohedral grid with a (4, 4) topology. The TGA property, fluorescent property and photocatalytic activity of complexes 1–6 have been investigated and discussed. - Graphical abstract: Six Co{sup II} complexes of bis(N-imidazolyl/benzimidazolyl)pyridazine were synthesized and structurally characterized. The fluorescence properties and photocatalytic activity for dye degradation under UV light of all complexes have been investigated and discussed. Display Omitted - Highlights: • Six new Co{sup II} complexes with bis(N-imidazolyl/benzimidazolyl) pyridazine. • Structural analysis of all complexes. • Fluorescent property of all complexes. • Photocatalytic activity for dye degradation under UV light of all complexes.

  20. Dibromidobis(3,5-dimethyl-1H-pyrazole-κN 2)cobalt(II)

    PubMed Central

    Tomyn, Stefania; Pavlenko, Vadim A.; Gumienna-Kontecka, Elżbieta; Penkova, Larysa; Kotova, Natalia V.

    2011-01-01

    In the mononuclear title complex, [CoBr2(C5H8N2)2], the CoII atom is coordinated by two N atoms from two monodentate 3,5-dimethyl­pyrazole ligands and two Br atoms in a highly distorted tetra­hedral geometry. In the crystal, the complex mol­ecules are linked by inter­molecular N—H⋯Br hydrogen bonds into chains along [101]. An intra­molecular N—H⋯Br hydrogen bond is also present. PMID:22219744

  1. Di- and tetra-nuclear copper(II), nickel(II), and cobalt(II) complexes of four bis-tetradentate triazole-based ligands: synthesis, structure, and magnetic properties.

    PubMed

    Olguín, Juan; Kalisz, Marguerite; Clérac, Rodolphe; Brooker, Sally

    2012-05-07

    Four bis-tetradentate N(4)-substituted-3,5-{bis[bis-N-(2-pyridinemethyl)]aminomethyl}-4H-1,2,4-triazole ligands, L(Tz1)-L(Tz4), differing only in the triazole N(4) substituent R (where R is amino, pyrrolyl, phenyl, or 4-tertbutylphenyl, respectively) have been synthesized, characterized, and reacted with M(II)(BF(4))(2)·6H(2)O (M(II) = Cu, Ni or Co) and Co(SCN)(2). Experiments using all 16 possible combinations of metal salt and L(TzR) were carried out: 14 pure complexes were obtained, 11 of which are dinuclear, while the other three are tetranuclear. The dinuclear complexes include two copper(II) complexes, [Cu(II)(2)(L(Tz2))(H(2)O)(4)](BF(4))(4) (2), [Cu(II)(2)(L(Tz4))(BF(4))(2)](BF(4))(2) (4); two nickel(II) complexes, [Ni(II)(2)(L(Tz1))(H(2)O)(3)(CH(3)CN)](BF(4))(4)·0.5(CH(3)CN) (5) and [Ni(II)(2)(L(Tz4))(H(2)O)(4)](BF(4))(4)·H(2)O (8); and seven cobalt(II) complexes, [Co(II)(2)(L(Tz1))(μ-BF(4))](BF(4))(3)·H(2)O (9), [Co(II)(2)(L(Tz2))(μ-BF(4))](BF(4))(3)·2H(2)O (10), [Co(II)(2)(L(Tz3))(H(2)O)(2)](BF(4))(4) (11), [Co(II)(2)(L(Tz4))(μ-BF(4))](BF(4))(3)·3H(2)O (12), [Co(II)(2)(L(Tz1))(SCN)(4)]·3H(2)O (13), [Co(II)(2)(L(Tz2))(SCN)(4)]·2H(2)O (14), and [Co(II)(2)(L(Tz3))(SCN)(4)]·H(2)O (15). The tetranuclear complexes are [Cu(II)(4)(L(Tz1))(2)(H(2)O)(2)(BF(4))(2)](BF(4))(6) (1), [Cu(II)(4)(L(Tz3))(2)(H(2)O)(2)(μ-F)(2)](BF(4))(6)·0.5H(2)O (3), and [Ni(II)(4)(L(Tz3))(2)(H(2)O)(4)(μ-F(2))](BF(4))(6)·6.5H(2)O (7). Single crystal X-ray structure determinations revealed different solvent content from that found by microanalysis of the bulk sample after drying under a vacuum and confirmed that 5', 8', 9', 11', 12', and 15' are dinuclear while 1' and 7' are tetranuclear. As expected, magnetic measurements showed that weak antiferromagnetic intracomplex interactions are present in 1, 2, 4, 7, and 8, stabilizing a singlet spin ground state. All seven of the dinuclear cobalt(II) complexes, 9-15, have similar magnetic behavior and remain in the [HS-HS] state

  2. A cobalt (II) complex with 6-methylpicolinate: Synthesis, characterization, second- and third-order nonlinear optical properties, and DFT calculations

    NASA Astrophysics Data System (ADS)

    Altürk, Sümeyye; Avcı, Davut; Tamer, Ömer; Atalay, Yusuf; Şahin, Onur

    2016-11-01

    A cobalt(II) complex of 6-methylpicolinic acid, [Co(6-Mepic)2(H2O)2]·2H2O, was prepared and fully determined by single crystal X-ray crystal structure analysis as well as FT-IR, FT-Raman. UV-vis spectra were recorded within different solvents, to illustrate electronic transitions and molecular charge transfer within complex 1. The coordination sphere of complex 1 is a distorted octahedron according to single crystal X-ray results. Moreover, DFT (density functional theory) calculations with HSEH1PBE/6-311 G(d,p) level were carried out to back up the experimental results, and form base for future work in advanced level. Hyperconjugative interactions, intramolecular charge transfer (ICT), molecular stability and bond strength were researched by the using natural bond orbital (NBO) analysis. X-ray and NBO analysis results demonsrate that O-H···O hydrogen bonds between the water molecules and carboxylate oxygen atoms form a 2D supramolecular network, and also adjacent 2D networks connected by C-H···π and π···π interactions to form a 3D supramolecular network. Additionally, the second- and third-order nonlinear optical parameters of complex 1 were computed at DFT/HSEH1PBE/6-311 G(d,p) level. The refractive index (n) was calculated by using the Lorentz-Lorenz equation in order to investigate polarization behavior of complex 1 in different solvent polarities. The first-order static hyperpolarizability (β) value is found to be lower than pNA value because of the inversion symmetry around Co (II). But the second-order static hyperpolarizability (γ) value is 2.45 times greater than pNA value (15×10-30 esu). According to these results, Co(II) complex can be considered as a candidate to NLO material. Lastly molecular electrostatic potential (MEP), frontier molecular orbital energies and related molecular parameters for complex 1 were evaluated.

  3. In vivo traffic of indium-111-oxine labeled human lymphocytes collected by automated apheresis

    SciTech Connect

    Read, E.J.; Keenan, A.M.; Carter, C.S.; Yolles, P.S.; Davey, R.J. )

    1990-06-01

    The in vivo traffic patterns of autologous lymphocytes were studied in five normal human volunteers using lymphocytes obtained by automated apheresis, separated on Ficoll-Hypaque gradients, and labeled ex vivo with {sup 111}In-oxine. Final lymphocyte infusions contained 1.8-3.1 X 10(9) cells and 270-390 microCi (9.99-14.43 MBq) {sup 111}In, or 11-17 microCi (0.41-0.63 MBq) per 10(8) lymphocytes. Gamma imaging showed transient lung uptake and significant retention of radioactivity in the liver and spleen. Progressive uptake of activity in normal, nonpalpable axillary and inguinal lymph nodes was seen from 24 to 96 hr. Accumulation of radioactivity also was demonstrated at the forearm skin test site, as well as in its associated epitrochlear and axillary lymph nodes, in a subject who had been tested for delayed hypersensitivity with tetanus toxoid. Indium-111-oxine labeled human lymphocytes may provide a useful tool for future studies of normal and abnormal lymphocyte traffic.

  4. New dinuclear cobalt(II) and zinc(II) complexes of a carboxylate-rich dinucleating ligand: synthesis, structure, spectroscopic characterization, and their interactions with sugars.

    PubMed

    Bera, Manindranath; Curtiss, Ashley B S; Musie, Ghezai T; Powell, Douglas R

    2012-11-19

    Sugar-metal ion interactions in aqueous medium are involved in many biochemical processes such as the transport and storage of metals, the function and regulation of sugar-metabolizing metalloenzymes, the mechanism of action of metal-containing pharmaceuticals, and toxic metal metabolism. To understand such interactions we synthesized and fully characterized two new dinuclear cobalt(II) and zinc(II) complexes as carbohydrate binding models for xylose/glucose isomerases (XGI). Synthesis of the dicobalt complex, Na3[Co2(ccdp)(μ-HCO2)]BF4·9H2O·2CH3OH (1), was performed in methanol with stoichiometric amounts of Co(BF4)2·6H2O and the dinucleating ligand, H5ccdp (H5ccdp = N,N'-bis[2-carboxybenzomethyl]-N,N'-bis[carboxymethyl]-1,3-diaminopropan-2-ol), in the presence of NaOH at ambient temperature in an argon glovebox. Similarly, the dizinc complex, [NMe4]2[Zn2(ccdp)(μ-OAc)]·CH3OH (2), was synthesized from Zn(OAc)2·2H2O and H5ccdp in the presence of NMe4OH at ambient temperature in methanol. Binding of the complexes with carbohydrates was investigated under different reaction conditions. In aqueous alkaline media, complexes 1 and 2 showed chelating ability towards the biologically important sugars, d-glucose and d-xylose, and a polyalcohol enzyme inhibitor (xylitol). In solution, each complex forms a 1:1 complex-substrate bound product with specific binding constant values. Synthesis, characterization details, and substrate binding using spectroscopic techniques and single-crystal X-ray diffraction are reported.

  5. Crystal structure of bis-(di-methyl-ammonium) hexa-aqua-cobalt(II) bis-(sulfate) dihydrate.

    PubMed

    Held, Peter

    2015-04-01

    The title salt, (C2H8N)2[Co(H2O)6)](SO4)2·2H2O, is isotypic with (C2H8N)2[Ni(H2O)6)](SO4)2·2H2O. The Co-O bond lengths in the [Co(H2O)6](2+) complex cation show very similar distances as in the related Tutton salt (NH4)2[Co(H2O)6)](SO4)2 [average 2.093 (17) Å], but are significantly longer than in the isotypic Ni(II) compound (Δd ≃ 0.04 Å). The cobalt cation reaches an overall bond-valence sum of 1.97 valence units. The S-O distances are nearly equal, ranging from 1.454 (4) to 1.470 (3) Å [mean 1.465 (12) Å]; however, the O-S-O angles vary clearly from 108.1 (2) to 110.2 (2)° [average bond angle 109.5 (9)°]. The non-coordinating water mol-ecules and di-methyl-ammonium cations connect the sulfate tetrahedra and the [Co(H2O)6](2+) octa-hedron via O-H⋯O and N-H⋯O hydrogen bonds of weak up to medium strength into a three-dimensional framework whereby the complex metal cations and sulfate anions are arranged in sheets parallel to (001).

  6. Rates of water exchange for two cobalt(II) heteropoly-oxotungstate compounds in aqueous solution

    SciTech Connect

    Ohlin, C. Andre; Harley, Stephen J.; McAlpin, J. Gregory; Hocking, Rosalie K.; Mercado, Brandon Q.; Johnson, Rene L.; Villa, Eric M.; Fidler, Mary Kate; Olmstead, Marilyn M.; Spiccia, Leone; Britt, R. David; Casey, William H.

    2011-03-17

    Polyoxometalate ions are used as ligands in water-oxidation processes related to solar energy production. An important step in these reactions is the association and dissociation of water from the catalytic sites, the rates of which are unknown. Here we report the exchange rates of water ligated to CoII atoms in two polyoxotungstate sandwich molecules using the 17O-NMR-based Swift–Connick method. The compounds were the [Co4(H2O)2(B-α-W9O34)2]-10 and the larger αββα-[Co4(H2O)2(P2W15O56)2]-16 ions, each with two water molecules bound trans to one another in a CoII sandwich between the tungstate ligands. The clusters, in both solid and solution state, were characterized by a range of methods, including NMR, EPR, FT-IR, UV-Vis, and EXAFS spectroscopy, ESI-MS, single-crystal X-ray crystallography, and potentiometry. For [Co4(H2O)2(B-α-PW9O34)2]-10 at pH 5.4, we estimate: k 298=1.5(5)±0.3×106 s-1, ΔH=39.8±0.4 kJ mol-1, ΔS=+7.1±1.2 J mol-1 K-1 and ΔV=5.6 ±1.6 cm3 mol-1. For the Wells–Dawson sandwich cluster (αββα-[Co4(H2O)2(P2W15O56)2]-16) at pH 5.54, we find: k298=1.6(2)±0.3×106 s-1, ΔH=27.6±0.4 kJ mol-1 ΔS=-33±1.3 J mol-1 K-1 and ΔV=2.2±1.4 cm3mol-1 at pH 5.2. The molecules are clearly stable and monospecific in slightly acidic solutions, but dissociate in strongly acidic solutions. This dissociation is detectable by EPR

  7. Bioaccessibility testing of cobalt compounds.

    PubMed

    Stopford, Woodhall; Turner, John; Cappellini, Danielle; Brock, Tom

    2003-08-01

    Testing of metal compounds for solubility in artificial fluids has been used for many years to assist determining human health risk from exposure to specific compounds of concern. In lieu of obtaining bioavailability data from samples of urine, blood, or other tissues, these studies measured solubility of compounds in various artificial fluids as a surrogate for bioavailability. In this context, the measurement of metal "bioaccessibility" can be used as an in vitro substitute for measuring metal bioavailability. Bioaccessibility can be defined as a value representing the availability of metal for absorption when dissolved in in vitro surrogates of body fluids or juices. The aim of this study was to measure and compare the bioaccessibility of selected cobalt compounds in artificial human tissue fluids and human serum. A second aim was to initiate studies to experimentally validate an in vitro methodology that would provide a conservative estimate of cobalt bioavailability in the assessment of dose from human exposure to various species of cobalt compounds. This study evaluated the bioaccessibility of cobalt(II) from 11 selected cobalt compounds and an alloy in 2 physical forms in 5 surrogate human tissue fluids and human serum. Four (4) separate extraction times were used up to 72 hours. The effect of variables such as pH, dissolution time, and mass-ion effect on cobalt bioaccessibility were assessed as well. We found that the species of cobalt compound as well as the physico-chemical properties of the surrogate fluids, especially pH, had a major impact on cobalt solubility. Cobalt salts such as cobalt(II) sulfate heptahydrate were highly soluble, whereas cobalt alloys used in medical implants and cobalt aluminate spinels used as pigments, showed minimal dissolution over the period of the assay.

  8. Effect of ligand denticity on the nitric oxide reactivity of cobalt(ii) complexes.

    PubMed

    Deka, Hemanta; Ghosh, Somnath; Saha, Soumen; Gogoi, Kuldeep; Mondal, Biplab

    2016-07-05

    The activation of nitric oxide (NO) by transition metal complexes has attracted a wide range of research activity. To study the role of ligand denticity on the NO reactivity of Co(ii) complexes, three complexes (, and ) were prepared with ligands , and [ = N(1),N(2)-bis(2,4,6-trimethylbenzyl)ethane-1,2-diamine; = N(1)-(2,4,6-trimethylbenzyl)-N(2)-(2-((2,4,6-trimethylbenzyl)amino)ethyl)ethane-1,2-diamine] and = N(1)-(2,4,6-trimethylbenzyl)-N(2),N(2)-bis(2-((2,4,6-trimethylbenzyl)amino)ethyl)ethane-1,2-diamine], respectively. The complexes differ from each other in terms of denticity and flexibility of the ligand frameworks. In degassed methanol solution, they were exposed to NO gas and their reactivity was studied using various spectroscopic techniques. In the case of complex with a bidentate ligand, reductive nitrosylation of the metal ion with concomitant dinitrosation of the ligand framework was observed. Complex with a tridentate ligand did not undergo reductive nitrosylation; rather, the formation of [Co(III)(NO(-))] was observed. The nitrosyl complexes were isolated and structurally characterized. On the other hand, complex with a tetradentate tripodal ligand did not react with NO. This can be attributed to the geometry of the complex as well as due to the accessibility of the corresponding redox potential.

  9. Synthesis, structure, properties and immobilization on a gold surface of the monoribbed-functionalized tris-dioximate cobalt(II) clathrochelates and an electrocatalytic hydrogen production from H+ ions.

    PubMed

    Voloshin, Y Z; Belov, A S; Vologzhanina, A V; Aleksandrov, G G; Dolganov, A V; Novikov, V V; Varzatskii, O A; Bubnov, Y N

    2012-05-28

    The cycloaddition of the mono- and dichloroglyoximes to the cobalt(II) bis-α-benzyldioximate afforded the cobalt(II) mono- and dichloroclathrochelates in moderate yields (40-60%). These complexes undergo nucleophilic substitution of their reactive chlorine atoms with aliphatic amines, alcohols and thiolate anions. In the case of ethylenediamine and 1,2-ethanedithiol, only the macrobicyclic products with α,α'-N(2)- and α,α'-S(2)-alicyclic six-numbered ribbed fragments were obtained. The cobalt(II) cage complexes with terminal mercapto groups were synthesized using aliphatic dithiols. The crystal and molecular structures of the six cobalt(II) clathrochelates were obtained by X-ray diffraction. Their CoN(6)-coordination polyhedra possess a geometry intermediate between a trigonal prism and a trigonal antiprism, and the encapsulated cobalt(II) ions are shifted from their centres due to the structural Jahn-Teller effect with the Co-N distances varying significantly (by 0.10-0.26 Å). The electrochemistry of the complexes obtained was studied by cyclic voltammetry (CV). The anodic waves correspond to the quasi-reversible Co(2+/3+) oxidations, whereas the cathodic ranges contain the quasi-reversibile waves assigned to the Co(2+/+) reductions; all the cobalt(i)-containing clathrochelate anions formed are stable in the CV time scale. The electrocatalytic properties of the cobalt complexes obtained were studied in the production of hydrogen from H(+) ions: the addition of HClO(4) resulted in the formation of the same catalytic cathodic reduction Co(2+/+) waves. The controlled-potential electrolysis with gas chromatography analysis confirmed the production of H(2) in high Faraday yields. The efficiency of this electrocatalytic process was enhanced by an immobilization of the complexes with terminal mercapto groups on a surface of the working gold electrode.

  10. gamma-Tocotrienol modulates the paracrine secretion of VEGF induced by cobalt(II) chloride via ERK signaling pathway in gastric adenocarcinoma SGC-7901 cell line.

    PubMed

    Bi, Sheng; Liu, Jia-Ren; Li, Yang; Wang, Qi; Liu, Hui-Kun; Yan, Ya-Geng; Chen, Bing-Qing; Sun, Wen-Guang

    2010-01-01

    Hypoxia is a common characteristic feature of solid tumors, and carcinoma cells are known to secrete many growth factors. These growth factors, such as vascular endothelial growth factor (VEGF), play a major role in the regulation of tumor angiogenesis and metastasis. In this study, the effect of gamma-tocotrienol, a natural product commonly found in palm oil and rice bran, on the accumulation of HIF-1alpha protein and the paracrine secretion of VEGF in human gastric adenocarcinoma SGC-7901 cell line induced by cobalt(II) chloride (as a hypoxia mimic) was investigated. These results showed that cobalt(II) chloride induced the high expression of VEGF in SGC-7901 cells at dose of 150 micromol/L for 24h. Both basal level and cobalt(II) chloride-induced HIF-1alpha protein accumulation and VEGF paracrine secretion were inhibited in SGC-7901 cells treated with gamma-tocotrienol at 60 micromol/L treatment for 24 h. U0126, a MEK1/2 inhibitor, decreased the expression of HIF-1alpha protein and the paracrine secretion of VEGF under normoxic and hypoxic conditions. In this study, gamma-tocotrienol also significantly inhibited the hypoxia-stimulated expression of phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2). The mechanism seems to involve in inhibiting hypoxia-mediated activation of p-ERK1/2, it leads to a marked decrease in hypoxia-induced HIF-1alpha protein accumulation and VEGF secretion. These data suggest that HIF-1alpha/VEGF could be a promising target for gamma-tocotrienol in an effective method of chemoprevention and chemotherapy in human gastric cancer.

  11. The determination of cobalt(II) at DME using catalytic hydrogen current technique in various water samples, agricultural materials and pharmaceuticals.

    PubMed

    Kanchi, S; Saraswathi, K; Venkatasubba Naidu, N

    2011-12-01

    Two novel and facile ligands ammonium piperidine dithiocarbamate (Amm Pip-DTC) and ammonium morpholine dithiocarbamate (Amm Mor-DTC) were synthesized for the development of rapid and cost effective catalytic hydrogen current technique to analyze cobalt(II) in the presence of NH(4)Cl-NH(4)OH at pH 7.8 and 8.4 with Amm Pip-DTC and Amm Mor-DTC. These ligands produce catalytic hydrogen currents with Co(II) at peak potentials -1.24 V and -1.44 V vs. SCE respectively. Quantitative experimental conditions are developed by studying effect of pH, supporting electrolyte (NH(4)Cl), ligand and metal ion concentrations and effect of adverse ions on peak height to improve the sensitivity, selectivity and detection limits of the catalytic hydrogen current technique and compared it in terms of Student's t test and variance ratio f test with differential pulse polarographic (DPP) method. The developed technique was applied for the analysis of cobalt(II) in various water samples, agricultural materials and pharmaceuticals and the results obtained are in good agreement with the DPP data.

  12. Cobalt(II) Porphyrin-Catalyzed Intramolecular Cyclopropanation of N-Alkyl Indoles/Pyrroles with Alkylcarbene: Efficient Synthesis of Polycyclic N-Heterocycles.

    PubMed

    Reddy, Annapureddy Rajasekar; Hao, Fei; Wu, Kai; Zhou, Cong-Ying; Che, Chi-Ming

    2016-01-26

    A protocol on chemoselective cobalt(II) porphyrin-catalyzed intramolecular cyclopropanation of N-alkyl indoles/pyrroles with alkylcarbenes has been developed. The reaction enables the rapid construction of a range of nitrogen-containing polycyclic compounds in moderate to high yields from readily accessible materials. These N-containing polycyclic compounds can be converted into a variety of N-heterocycles with potential synthetic and biological interest. Compared to their N-tosylhydrazone counterparts, the use of bulky N-2,4,6-triisopropylbenzenesulfonyl hydrazones as carbene precursors allows cyclopropanation to occur under milder reaction conditions.

  13. 1,2,4,5-benzenetetracarboxylate- and 2,2'-bipyrimidine-containing cobalt(II) coordination polymers: preparation, crystal structure, and magnetic properties.

    PubMed

    Fabelo, Oscar; Pasán, Jorge; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

    2008-05-05

    Three new mixed-ligand cobalt(II) complexes of formula [Co2(H2O)6(bta)(bpym)]n.4nH2O (1), [Co2(H2O)2(bta)(bpym)]n (2), and [Co2(H2O)4(bta)(bpym)]n.2nH2O ( 3) (bpym = 2,2'-bipyrimidine and H 4bta = 1,2,4,5-benzenetretracaboxylic acid) have been synthesized and characterized by single crystal X-ray diffraction. 1 is a chain compound of mer-triaquacobalt(II) units which are linked through regular alternating bis-bidentate bpym and bis-monodentate bta groups. 2 and 3 are three-dimensional compounds where aquacobalt(II) ( 2) and cis-diaquacobalt(II) ( 3) entities are linked by bis-bidentate bpym ( 2 and 3) and tetrakis- ( 2 and 3) and octakis-monodentate ( 2) bta ligands. The cobalt atoms in 1- 3 exhibit somewhat distorted octahedral surroundings. Two bpym-nitrogen atoms ( 1- 3) and either two bta-oxygens ( 2) or one bta-oxygen and a water molecule ( 1 and 3) build the equatorial plane, whereas the axial positions are filled either by two water molecules ( 1) or by a bta-oxygen atom and a water molecule ( 2 and 3). The values of the cobalt-cobalt separation across the bridging bpym vary in the range 5.684(2)-5.7752(7) A, whereas those through the bta bridge cover the ranges 5.288(2)-5.7503(5) A (across the anti-syn carboxylate) and 7.715(3)-11.387(1) A (across the phenyl ring). The magnetic properties of 1- 3 have been investigated in the temperature range 1.9-290 K. They are all typical of an overall antiferromagnetic coupling with the maxima of the magnetic susceptibility at 14.5 ( 1) and 11.5 K ( 2 and 3). Although exchange pathways through bis-bidentate bpym and carboxylate-bta in different coordination modes are involved in 1- 3, their magnetic behavior is practically governed by that across the bpym bridge, the magnitude of the exchange coupling being J = -5.59(2) ( 1), -4.41(2) ( 2), and -4.49(2) ( 3) with the Hamiltonian H = - JS 1 S 2.

  14. Computational, electrochemical, and spectroscopic studies of two mononuclear cobaloximes: the influence of an axial pyridine and solvent on the redox behaviour and evidence for pyridine coordination to cobalt(i) and cobalt(ii) metal centres.

    PubMed

    Lawrence, Mark A W; Celestine, Michael J; Artis, Edward T; Joseph, Lorne S; Esquivel, Deisy L; Ledbetter, Abram J; Cropek, Donald M; Jarrett, William L; Bayse, Craig A; Brewer, Matthew I; Holder, Alvin A

    2016-06-21

    [Co(dmgBF2)2(H2O)2] (where dmgBF2 = difluoroboryldimethylglyoximato) was used to synthesize [Co(dmgBF2)2(H2O)(py)]·0.5(CH3)2CO (where py = pyridine) in acetone. The formulation of complex was confirmed by elemental analysis, high resolution MS, and various spectroscopic techniques. The complex [Co(dmgBF2)2(solv)(py)] (where solv = solvent) was readily formed in situ upon the addition of pyridine to complex . A spectrophotometric titration involving complex and pyridine proved the formation of such a species, with formation constants, log K = 5.5, 5.1, 5.0, 4.4, and 3.1 in 2-butanone, dichloromethane, acetone, 1,2-difluorobenzene/acetone (4 : 1, v/v), and acetonitrile, respectively, at 20 °C. In strongly coordinating solvents, such as acetonitrile, the lower magnitude of K along with cyclic voltammetry, NMR, and UV-visible spectroscopic measurements indicated extensive dissociation of the axial pyridine. In strongly coordinating solvents, [Co(dmgBF2)2(solv)(py)] can only be distinguished from [Co(dmgBF2)2(solv)2] upon addition of an excess of pyridine, however, in weakly coordinating solvents the distinctions were apparent without the need for excess pyridine. The coordination of pyridine to the cobalt(ii) centre diminished the peak current at the Epc value of the Co(I/0) redox couple, which was indicative of the relative position of the reaction equilibrium. Herein we report the first experimental and theoretical (59)Co NMR spectroscopic data for the formation of Co(i) species of reduced cobaloximes in the presence and absence of py (and its derivatives) in CD3CN. From spectroelectrochemical studies, it was found that pyridine coordination to a cobalt(i) metal centre is more favourable than coordination to a cobalt(ii) metal centre as evident by the larger formation constant, log K = 4.6 versus 3.1, respectively, in acetonitrile at 20 °C. The electrosynthesis of hydrogen by complexes and in various solvents demonstrated the dramatic effects of the axial

  15. New cobalt(II) and nickel(II) complexes of benzyl carbazate Schiff bases: Syntheses, crystal structures, in vitro DNA and HSA binding studies.

    PubMed

    Nithya, Palanivelu; Helena, Sannasi; Simpson, Jim; Ilanchelian, Malaichamy; Muthusankar, Aathi; Govindarajan, Subbiah

    2016-12-01

    In the present study, new Schiff base complexes with the composition [M(NCS)2(L1)2]·nH2O, where M=Co (n=0) (1) and Ni (n=2) (2); [M(NCS)2(L2)2], M=Co (3) and Ni (4) as well as [M(NCS)2(L3)2], M=Co (5) and Ni (6); (L1=benzyl 2-(propan-2-ylidene)hydrazinecarboxylate, L2=benzyl 2-(butan-2-ylidene)hydrazinecarboxylate and L3=benzyl 2-(pentan-3-ylidene)hydrazinecarboxylate) have been synthesized by a template method. The complexes were characterised by analytical methods, spectroscopic studies, thermal and X-ray diffraction techniques. The structures of all the complexes explore that the metal(II) cation has a trans-planar coordination environment, the monomeric units containing a six-coordinated metal center in octahedral geometry with N-bound isothiocyanate anions coordinated as terminal ligands. Furthermore, the binding of the two Schiff base ligands to the metal centers involves the azomethine nitrogen and the carbonyl oxygen in mutually trans configuration. The binding interactions of all the complexes with Calf thymus-deoxyribonucleic acid (CT-DNA) and human serum albumin (HSA) have been investigated using absorption and emission spectral techniques. The CT-DNA binding properties of these complexes reveal that they bind to CT-DNA through a partial intercalation mode and the binding constant values were calculated using the absorption and emission spectral data. The binding constant values (~10×10(6)moldm(-3)) indicate strong binding of metal complexes with CT-DNA. HSA binding interaction studies showed that the cobalt and nickel complexes can quench the intrinsic fluorescence of HSA through static quenching process. Also, molecular docking studies were supported out to apprehend the binding interactions of these complexes with DNA and HSA which offer new understandings into the experimental model observations.

  16. Crystal structure of a CoII coordination polymer: catena-poly[[μ-aqua-bis­(μ-2-methyl­propano­ato)-κ2 O:O′;κ2 O:O-cobalt(II)] monohydrate

    PubMed Central

    Gurzhiy, Vladislav V.; Aleksandrova, Julia V.; Pakina, Maria I.

    2017-01-01

    In the title cobalt(II) coordination polymer with isobutyrate ligands, {[Co{CH(CH3)2CO2}2(H2O)]·H2O}n, the Co2+ ion is hexa­coordinated in a slightly distorted octa­hedral coordination environment defined by two O atoms from two bridging water mol­ecules and four O atoms from four bridging carboxyl­ate ligands. The carboxyl­ates adopt two different coordination modes, μ-(κ2 O:O′) and μ-(κ2 O:O), forming a one-dimensional polymeric chain extending along [010]. The intra-chain cobalt⋯cobalt separation is 3.2029 (2) Å. The polymeric chains are linked by hydrogen bonds involving the water mol­ecules of solvation, giving a two-dimensional network structure lying parallel to (100). PMID:28316799

  17. Characteristics of polyaniline cobalt supported catalysts for epoxidation reactions.

    PubMed

    Kowalski, Grzegorz; Pielichowski, Jan; Grzesik, Mirosław

    2014-01-01

    A study of polyaniline (PANI) doping with various cobalt compounds, that is, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following acetonitrile/acetic acid solution or acetonitrile and then acetic acid solution. Moreover different ratios of Co(II) : PANI were studied. Catalysts obtained with both methods and at all ratios were investigated using various techniques including AAS and XPS spectroscopy. The optimum conditions for preparation of PANI/Co catalysts were established. Catalytic activity of polyaniline cobalt(II) supported catalysts was tested in dec-1-ene epoxidation with molecular oxygen at room temperature. The relationship between the amount of cobalt species, measured with both AAS and XPS techniques, and the activity of PANI-Co catalysts has been established.

  18. Characteristics of Polyaniline Cobalt Supported Catalysts for Epoxidation Reactions

    PubMed Central

    Kowalski, Grzegorz; Pielichowski, Jan; Grzesik, Mirosław

    2014-01-01

    A study of polyaniline (PANI) doping with various cobalt compounds, that is, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following acetonitrile/acetic acid solution or acetonitrile and then acetic acid solution. Moreover different ratios of Co(II) : PANI were studied. Catalysts obtained with both methods and at all ratios were investigated using various techniques including AAS and XPS spectroscopy. The optimum conditions for preparation of PANI/Co catalysts were established. Catalytic activity of polyaniline cobalt(II) supported catalysts was tested in dec-1-ene epoxidation with molecular oxygen at room temperature. The relationship between the amount of cobalt species, measured with both AAS and XPS techniques, and the activity of PANI-Co catalysts has been established. PMID:24701183

  19. In vivo crossmatching with Tc-99m-RBC's and In-111-oxine-RBC's

    SciTech Connect

    Marcus, C.S.; Myhre, B.A.; Angulo, M.C.; Salk, R.D.; Essex, C.E.

    1984-01-01

    In vitro crossmatching techniques are often inadequate for patients who have received multiple prior transfusions. These patients usually have multiple antibodies to minor blood groups, not all of which are necessarily important to vivo. It becomes increasingly difficult to obtain appropriate units for transfusion, and often units are used with hopes that a minor group antibody will not be significantly active in vivo. If a transfusion reaction occurs, the unit is stopped. The authors have developed and successfully tested a method whereby 1.5 to 3c of potential donor RBC's are labeled with 25-50 ..mu..Ci of Tc-99m using the BNL kits. After injection, samples are drawn at 10, 20, 60, and 120 minutes and the RBC survival is measured. If it is desirable to test 2 units simultaneously, the authors use 400 ..mu..Ci Tc-99m to label an RBC aliquot of one unit and 25 ..mu..Ci In-111-oxine to label the other; both labeled aliquots are injected together. The method is simple and reliable. In addition to assessing compatibility, the authors may also estimate the % viability of transfused, compatible RBC's by starting with 400 ..mu..Ci of Tc-99m and multiplying % survival at 24 hours by 1.2. For 24 hr. survival measurements of IN-111-oxine-RBC's, 25 ..mu..Ci is adequate and no multiplication factor is necessary. The authors have performed 13 in vivo crossmatches, 4 of which were double, in 6 patients. One documented mild transfusion reaction occurred. There were no false positive or false negative results.

  20. Indium-111-oxine labeled platelet kinetics in patients with diabetes mellitus

    SciTech Connect

    Forstrom, L.A.; Luikens, B.; Johnson, T.

    1984-01-01

    The possible role of abnormal platelet function in the pathogenesis of vascular disease in patients with diabetes mellitus remains controversial. In vitro studies have shown variable alterations in platelet function in such patients. Studies of in vivo platelet kinetics in diabetic patients have been inconclusive, although decreased platelet survival has been observed in some cases. Earlier studies were carried out using chromium-51 or selenium-75 for platelet labeling. The authors have performed Indium-111-oxine labeled platelet kinetic and biodistribution studies in 4 patients with diabetes mellitus (ages 49-61 years), and in 4 control subjects (ages 46-60 years). All subjects were male. All diabetic patients were poorly controlled at the time of study, with blood glucose > 140 mg% and hemoglobin A-1c > 10%. Autologous platelets were labeled with Indium-111-oxine in ACD:plasma by previously reported methods, and reinjected in a dose of approximately 50 ..mu..Ci (range 42-67..mu..Ci). Average recovery of the injected platelets was 67% (range 41-85%). Computer analyzed images at 24 hours showed no significant difference in liver uptake between diabetic and control subjects. Mildly increased splenic uptake in diabetic patients was of borderline significance (p=.07). Platelet survival was slightly decreased in diabetic subjects by 3 of 4 models utilized (linear, exponential, multiple hit and weighted mean), although the difference achieved significance only for the weighted man model (p=.05). These data support observations by earlier methods which suggest that platelet survival may be decreased in patients with diabetes mellitus.

  1. Binding, Electrochemical Activation and Cleavage of DNA by Cobalt(II)tetrakis-N-Methylpyridyl Porphyrin and its β-Pyrrole Brominated Derivative

    PubMed Central

    Yellappa, Shivaraj; Seetharamappa, Jaldappagari; Rogers, Lisa M.; Chitta, Raghu; Singhal, Ram P.; D’Souza, Francis

    2008-01-01

    The binding of nucleic acids by water soluble cobalt(II) tetrakis-N-methylpyridyl porphyrin, (TMPyP)Co and its highly electron deficient derivative, cobalt(II) tetrakis-N-methyl pyridyl-β-octabromoporphyrin, (Br8TMPyP)Co was investigated by UV-visible absorption, circular dichroism (CD), electrochemical and gel electrophoresis methods. The changes of the absorption spectra during the titration of these complexes with polynucleotides revealed a shift in the absorption maxima and a hypochromicity of the porphyrin Soret bands. The intrinsic binding constants were found to be in the range of 105 – 106 M−1. These values were higher for more electron deficient (Br8TMPyP)Co. Induced CD bands were noticed in the Soret region of the complexes due to the interaction of these complexes with different polynucleotides and an analysis of the CD spectra supported mainly external mode of binding. Electrochemical studies revealed the cleavage of polynucleotide by (TMPyP)Co and (Br8TMPyP)Co in the presence of oxygen preferentially at the A-T base pair region. Gel electrophoresis experiments further supported the cleavage of nucleic acids. The results indicate that the β-pyrrole brominated porphyrin, (Br8TMPyP)Co binds strongly and cleaves nucleic acids efficiently as compared to (TMPyP)Co. This electrolytic procedure offers a unique tool in biotechnology for cleaving double-stranded DNA with specificity at the A-T regions. PMID:17105219

  2. Molybdophosphonate clusters as building blocks in the oxomolybdate-organodiphosphonate/cobalt(II)-organoimine system: structural influences of secondary metal coordination preferences and diphosphonate tether lengths.

    PubMed

    Armatas, N Gabriel; Allis, Damian G; Prosvirin, Andrew; Carnutu, Gabriel; O'Connor, Charles J; Dunbar, Kim; Zubieta, Jon

    2008-02-04

    Hydrothermal conditions have been used in the preparation of a series of organic-inorganic hybrid materials of the cobalt-molybdophosphonate family. The reactions of MoO(3), cobalt(II) acetate or cobalt(II) acetylacetonate, tetra-2-pyridylpyrazine (tpyprz), and organodiphosphonic acids H(2)O(3)P(CH(2))nPO(3)H(2) (n = 1-5 and 9) of varying tether lengths yielded compounds of the general type {Co(2)(tpyprz)(H(2)O)(m)}4+/MoxOy{O(3)P(CH(2))(n)PO(3)}z. The recurring theme of the structural chemistry is the incorporation of {Mo(5)O(15)(O(3)PR)(2)}(4-) clusters as molecular building blocks observed in the structures of nine phases (compounds 2-9 and 11). The structural consequences of variations in reaction conditions are most apparent in the series with propylene diphosphonate, where four unique structures 4-7 are observed, including two distinct three-dimensional architectures for compounds 5 and 6 whose formulations differ only in the number of water molecules of crystallization. With pentyldiphosphonate, a second phase 10 is obtained which exhibits a unique cluster building block, the hexamolybdate [Mo(6)O(18){O(3)P(CH(2))(5)PO(3)}](4-). In the case of methylenediphosphonic acid, a third structural motif, the trinuclear {(Mo(3)O(8))(O(3)PCH(2)PO(3))}2- subunit, is observed in compound 1. The structural chemistry of compounds 1-11 of this study is quite distinct from that of the {Ni(2)(tpyprz)(H(2)O)(m)}(4+)/Mo(x)O(y){O(3)P(CH(2))(n)PO(3)}z family, as well as that of the copper-based family. The structural diversity of this general class of materials reflects the coordination preferences of the M(II) sites, the extent of aqua ligation to the M(II) sites, the participation of both phosphate oxygen atoms and molybdate oxo-groups in linking to the M(II) sites, and the variability in the number of attachment sites at the molybdophosphonate clusters. Since the charge densities at the peripheral oxygen atoms of the clusters are quite uniform, the attachment of {M(2)(tpyprz

  3. Tetra­aqua­bis­[2-(2-nitro­phen­yl)acetato-κO]cobalt(II)

    PubMed Central

    Danish, Muhammad; Tahir, Muhammad Nawaz; Iftikhar, Sana; Raza, Muhammad Asam; Ashfaq, Muhammad

    2015-01-01

    The mol­ecule of the title compound, [Co(C8H6NO4)2(H2O)4], is centrosymmetric. It is a cobalt(II) complex, bearing two (2-nitro­phen­yl)acetate and four aqua ligands. The coordination around the CoII atom is distorted octa­hedral, defined by four O atoms of water mol­ecules in the equatorial plane and by two carboxyl­ate O atoms at axial positions. The dihedral angles between the benzene ring and the acetate and nitro groups are 61.90 (10) and 19.21 (11)°, respectively. The water mol­ecules form O—H⋯O hydrogen bonds with the nitro and carboxyl­ate groups, leading to a layered structural arrangement parallel to (001). PMID:25844208

  4. Structural, MALDI-TOF-MS, magnetic and spectroscopic studies of new dinuclear copper(II), cobalt(II) and zinc(II) complexes containing a biomimicking μ-OH bridge.

    PubMed

    Núñez, Cristina; Bastida, Rufina; Macías, Alejandro; Valencia, Laura; Neuman, Nicolás I; Rizzi, Alberto C; Brondino, Carlos D; González, Pablo J; Capelo, José Luis; Lodeiro, Carlos

    2010-12-28

    The Py(2)N(4)S(2) octadentate coordinating ligand afforded dinuclear cobalt, copper and zinc complexes and the corresponding mixed metal compounds. The overall geometry and bonding modes have been deduced on the basis of elemental analysis data, MALDI-TOF-MS, IR, UV-vis and EPR spectroscopies, single-crystal X-Ray diffraction, conductivity and magnetic susceptibility measurements. In the copper and zinc complexes, a μ-hydroxo bridge links the two metal ions. In both cases, the coordination geometry is distorted octahedral. Magnetic and EPR data reveal weakly antiferromagnetic high spin Co(II) ions, compatible with a dinuclear structure. The magnetic characterization of the dinuclear Cu(II) compound indicates a ferromagnetically coupled dimer with weak antiferromagnetic intermolecular interactions. The intra-dimer ferromagnetic behaviour was unexpected for a Cu(II) dimer with such μ-hydroxo bridging topology. We discuss the influence on the magnetic properties of non-covalent interactions between the bridging moiety and the lattice free water molecules.

  5. Synthesis, structural and magnetic characterisation of iron(II/III), cobalt(II) and copper(II) cluster complexes of the polytopic ligand: N-(2-pyridyl)-3-carboxypropanamide.

    PubMed

    Russell, Mark E; Hawes, Chris S; Ferguson, Alan; Polson, Matthew I J; Chilton, Nicholas F; Moubaraki, Boujemaa; Murray, Keith S; Kruger, Paul E

    2013-10-07

    Herein we describe the synthesis, structural and magnetic characterisation of three transition metal cluster complexes that feature the polytopic ligand N-(2-pyridyl)-3-carboxypropanamide (H2L): [Fe3(III)Fe2(II)(HL)6(O)(H2O)3][ClO4]5·3MeCN·4H2O, 1, [Co8(HL)8(O)(OH)4(MeOH)3(H2O)]-[ClO4]3·5MeOH·2H2O, 2, and [Cu6(L(ox))4(MeOH)(H2O)3]·MeOH, 3. Complex 1 is a mixed valence penta-nuclear iron cluster containing the archetypal {Fe3(III)O} triangular basic carboxylate cluster at its core, with two Fe(II) ions above and below the core coordinated to three bidentate pyridyl-amide groups. The structure of the octanuclear Co(II) complex, 2, is based upon a central Co4 square with the remaining four Co(II) centres at the 'wing-tips' of the complex. The cluster core is replete with bridging oxide, hydroxide and carboxylate groups. Cluster 3 contains an oxidised derivative of the ligand, L(ox), generated in situ through hydroxylation of an α-carbon atom. This hexanuclear cluster has a 'barrel-like' core and contains Cu(II) ions in both square planar and square-based pyramidal geometries. Bridging between Cu(II) centres is furnished by alkoxide and carboxylate groups. Magnetic studies on 1-3 reveals dominant antiferro-magnetic interactions for 1 and 2, leading to small non-zero spin ground states, while 3 shows ferro-magnetic exchange between the Cu(II) centres to give an S = 3 spin ground state.

  6. Enrichment of iron(III), cobalt(II), nickel(II), and copper(II) by solid-phase extraction with 1,8-dihydroxyanthraquinone anchored to silica gel before their determination by flame atomic absorption spectrometry.

    PubMed

    Goswami, Anupama; Singh, Ajai K

    2002-10-01

    A chelating matrix prepared by immobilizing 1,8-dihydroxyanthraquinone on silica gel modified with 3-aminopropyltriethoxysilane has been characterized by use of cross-polarization magic angle spinning (CPMAS) NMR, diffuse reflectance infrared Fourier transformation (DRIFT) spectroscopy, and thermogravimetric analysis and used to preconcentrate Fe(III), Co(II), Ni(II), and Cu(II) before their determination by flame atomic absorption spectrometry. The optimum pH ranges for quantitative sorption are 6.5-8.0, 6.0-7.0, 6.0-8.0, and 7.0-8.5 for Cu, Fe, Co, and Ni, respectively. All the metal ions can be desorbed with 2 mol L(-1) HCl or HNO3. The sorption capacity ( micromol g(-1) matrix) and preconcentration factor were 226.6, 250; 365.6, 300; 101.8, 150; and 109.0, 250 for Cu, Fe, Co, and Ni, respectively. The lowest concentration for quantitative recovery was 4.0, 3.3, 6.6, and 4.0 ng mL(-1), respectively for the four metal ions. The limits up to which electrolytes NaNO3, NaCl, NaBr, Na2SO4, and Na3PO4 and cations Ca(II) and Mg(II) can coexist with the four metal ions during their sorption without adverse effect are reported. The simultaneous enrichment and determination of all the four metals is possible if the total load of metal ions is less than the sorption capacity. Flame AAS was used to determine the metal ions in underground, tap, and river water samples (RSDcobalt content of pharmaceutical samples (multivitamin tablet) preconcentrated by use of this silica gel matrix and determined by FAAS was found to be 2.00 microg g(-1), with RSDtilde;1.7% (reported concentration level, 1.99 microg g(-1)).

  7. Technical considerations in the study of /sup 111/In-oxine labelled platelet survival patterns in dogs

    SciTech Connect

    Sharefkin, J.; Rich, N.M.

    1982-04-01

    A detailed technique for labelling canine platelets with /sup 111/In-oxine for the study of platelet survival patterns in four to six dogs at a time was developed. Useful modifications of earlier methods included splitting of the platelet rich plasma into multiple aliquots to improve pelleting efficiency at low gravity forces, use of saved platelet poor plasma to flush out injection syringes, and prompt use of commercial /sup 111/In-oxine sources 3 to 5 minutes after mixing with Ringer's Citrate Dextrose. Avoidable pitfalls of the method included excessive lengths of incubation time in plasma free medium and loss of labelling efficacy by exposure of the chelate to iron or other metal contaminants in glassware. The method was used to study changes in platelet survival time in dogs with large synthetic arterial prostheses, and gave results in good agreement with earlier studies using /sup 51/Cr labelled platelets.

  8. Unique ligand-radical character of an activated cobalt salen catalyst that is generated by aerobic oxidation of a cobalt(II) salen complex.

    PubMed

    Kurahashi, Takuya; Fujii, Hiroshi

    2013-04-01

    The Co(salen)(X) complex, where salen is chiral N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine and X is an external axial ligand, has been widely utilized as a versatile catalyst. The Co(salen)(X) complex is a stable solid that has been conventionally described as a Co(III)(salen)(X) complex. Recent theoretical calculations raised a new proposal that the Co(salen)(H2O)(SbF6) complex contains appreciable contribution from a Co(II)(salen(•+)) electronic structure (Kochem, A.; Kanso, H.; Baptiste, B.; Arora, H.; Philouze, C.; Jarjayes, O.; Vezin, H.; Luneau, D.; Orio, M.; Thomas, F. Inorg. Chem. 2012, 51, 10557-10571), while other theoretical calculations for Co(salen)(Cl) indicated a triplet Co(III)(salen) electronic structure (Kemper, S.; Hrobárik, P.; Kaupp, M.; Schlörer, N. E. J. Am. Chem. Soc. 2009, 131, 4172-4173). However, there have been no experimental data to evaluate these theoretical proposals. We herein report key experimental data on the electronic structure of the Co(salen)(X) complex (X = CF3SO3(-), SbF6(-), and p-MeC6H4SO3(-)). The X-ray crystallography shows that Co(salen)(OTf) has a square-planar N2O2 equatorial coordination sphere with OTf as an elongated external axial ligand. Magnetic susceptibility data indicate that Co(salen)(OTf) complexes belong to the S = 1 spin system. (1)H NMR measurements provide convincing evidence for the Co(II)(salen(•+))(X) character, which is estimated to be about 40% in addition to 60% Co(III)(salen)(X) character. The CH2Cl2 solution of Co(salen)(X) shows an intense near-IR absorption, which is assigned as overlapped transitions from a ligand-to-metal charge transfer in Co(III)(salen)(X) and a ligand-to-ligand charge transfer in Co(II)(salen(•+))(X). The present experimental study establishes that the electronic structure of Co(salen)(X) contains both Co(II)(salen(•+))(X) and Co(III)(salen)(X) character.

  9. Nanocellulose/nanobentonite composite anchored with multi-carboxyl functional groups as an adsorbent for the effective removal of Cobalt(II) from nuclear industry wastewater samples.

    PubMed

    Anirudhan, T S; Deepa, J R; Christa, J

    2016-04-01

    A novel adsorbent, poly(itaconic acid/methacrylic acid)-grafted-nanocellulose/nanobentonite composite [P(IA/MAA)-g-NC/NB] with multi carboxyl functional groups for the effective removal of Cobalt(II) [Co(II)] from aqueous solutions. The adsorbent was characterized using FTIR, XRD, SEM-EDS, AFM and potentiometric titrations before and after adsorption of Co(II) ions. FTIR spectra revealed that Co(II) adsorption on to the polymer may be due to the involvement of COOH groups. The surface morphological changes were observed by the SEM images. The pH was optimized as 6.0. An adsorbent dose of 2.0g/L found to be sufficient for the complete removal of Co(II) from 100mg/L at room temperature. Pseudo-first-order and pseudo-second-order models were tested to describe kinetic data and adsorption of Co(II) follows pseudo-second-order model. The equilibrium attained at 120min. Isotherm studies were conducted and data were analyzed using Langmuir, Freundlich and Sips isotherm models and best fit was Sips model. Thermodynamic study confirmed endothermic and physical nature of adsorption of the Co(II) onto the adsorbent. Desorption experiments were done with 0.1MHCl proved that without significant loss in performance adsorbent could be reused for six cycles. The practical efficacy and effectiveness of the adsorbent were tested using nuclear industrial wastewater. A double stage batch adsorption system was designed from the adsorption isotherm data of Co(II) by constructing operating lines.

  10. In vivo tracing of indium-111 oxine-labeled human peripheral blood mononuclear cells in patients with lymphatic malignancies

    SciTech Connect

    Mueller, C.Z.; Zielinski, C.C.; Linkesch, W.; Ludwig, H.; Sinzinger, H.

    1989-06-01

    The in vivo migration of (/sup 111/In)oxine-labeled peripheral mononuclear cells (PMNC) was studied in 20 patients with various lymphatic malignancies and palpable enlarged lymph nodes. The maximal labeling dose of 10 microCi (0.37 MBq) (/sup 111/In)oxine/10(8) PMNC was found not to adversely influence either cell viability or lymphocyte proliferation in vitro. For in vivo studies, 1.5 X 10(9) PMNC were gained by lymphapheresis and reinjected intravenously after radioactive labeling, 150 microCi (5.55 MBq). The labeling of enlarged palpable lymph nodes was achieved in three out of three patients with Hodgkin's disease and in five out of five with high-malignant lymphoma, whereas three out of seven patients with low malignant lymphoma and no patient with chronic lymphatic leukemia had positive lymph node imaging. We thus conclude that PMNC retain their ability to migrate after (/sup 111/In)oxine labeling and that these cells traffic to involved lymph nodes of some, but not all hematologic malignancies.

  11. Solid-phase extraction of cobalt(II) from lithium chloride solutions using a poly(vinyl chloride)-based polymer inclusion membrane with Aliquat 336 as the carrier.

    PubMed

    Kagaya, Shigehiro; Cattrall, Robert W; Kolev, Spas D

    2011-01-01

    The extraction of cobalt(II) from solutions containing various concentrations of lithium chloride, hydrochloric acid, and mixtures of lithium chloride plus hydrochloric acid is reported using a poly(vinyl chloride) (PVC)-based polymer inclusion membrane (PIM) containing 40% (w/w) Aliquat 336 as a carrier. The extraction from lithium chloride solutions and mixtures with hydrochloric acid is shown to be more effective than extraction from hydrochloric acid solutions alone. The solution concentrations giving the highest amounts of extraction are 7 mol L(-1) for lithium chloride and 8 mol L(-1) lithium chloride plus 1 mol L(-1) hydrochloric acid for mixed solutions. Cobalt(II) is easily stripped from the membrane using deionized water. The cobalt(II) species extracted into the membrane are CoCl(4)(2-) for lithium chloride solutions and HCoCl(4)(-) for mixed solutions; these form ion-pairs with Aliquat 336. It is also shown that both lithium chloride and hydrochloric acid are extracted by the PIM and suppress the extraction of cobalt(II) by forming ion-pairs in the membrane (i.e. R(3)MeN(+)·HCl(2)(-) for hydrochloric acid and R(3)MeN(+)·LiCl(2)(-) for lithium chloride).

  12. Low-temperature CVD of iron, cobalt, and nickel nitride thin films from bis[di(tert-butyl)amido]metal(II) precursors and ammonia

    SciTech Connect

    Cloud, Andrew N.; Abelson, John R.; Davis, Luke M.; Girolami, Gregory S.

    2014-03-15

    Thin films of late transition metal nitrides (where the metal is iron, cobalt, or nickel) are grown by low-pressure metalorganic chemical vapor deposition from bis[di(tert-butyl)amido]metal(II) precursors and ammonia. These metal nitrides are known to have useful mechanical and magnetic properties, but there are few thin film growth techniques to produce them based on a single precursor family. The authors report the deposition of metal nitride thin films below 300 °C from three recently synthesized M[N(t-Bu){sub 2}]{sub 2} precursors, where M = Fe, Co, and Ni, with growth onset as low as room temperature. Metal-rich phases are obtained with constant nitrogen content from growth onset to 200 °C over a range of feedstock partial pressures. Carbon contamination in the films is minimal for iron and cobalt nitride, but similar to the nitrogen concentration for nickel nitride. X-ray photoelectron spectroscopy indicates that the incorporated nitrogen is present as metal nitride, even for films grown at the reaction onset temperature. Deposition rates of up to 18 nm/min are observed. The film morphologies, growth rates, and compositions are consistent with a gas-phase transamination reaction that produces precursor species with high sticking coefficients and low surface mobilities.

  13. Effect of three bis-pyridyl-bis-amide ligands with various spacers on the structural diversity of new multifunctional cobalt(II) coordination polymers

    SciTech Connect

    Lin, Hong-Yan; Lu, Huizhe; Le, Mao; Luan, Jian; Wang, Xiu-Li; Liu, Guocheng; Zhang, Juwen

    2015-03-15

    Three new cobalt(II) coordination polymers [Co{sub 2}(1,4-NDC){sub 2}(3-bpye)(H{sub 2}O)] (1), [Co(1,4-NDC)(3-bpfp)(H{sub 2}O)] (2) and [Co(1,4-NDC)(3-bpcb)] (3) [3-bpye=N,N′-bis(3-pyridinecarboxamide)-1,2-ethane, 3-bpfp=bis(3-pyridylformyl)piperazine, 3-bpcb=N,N′-bis(3-pyridinecarboxamide)-1,4-benzene, and 1,4-H{sub 2}NDC=1,4-naphthalenedicarboxylic acid] have been hydrothermally synthesized. The structures of complexes 1–3 have been determined by X-ray single crystal diffraction analyses and further characterized by infrared spectroscopy (IR), powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Complex 1 is a 3D coordination structure with 8-connected (4{sup 20}.6{sup 8}) topology constructed from 3D [Co{sub 2}(1,4-NDC){sub 2}(H{sub 2}O)]{sub n} framework and bidentate 3-bpye ligands. Complex 2 shows 1D “cage+cage”-like chain formed by 1D [Co{sub 2}(1,4-NDC){sub 2}]{sub n} ribbon chains and [Co{sub 2}(3-bpfp){sub 2}] loops, which are further linked by hydrogen bonding interactions to form a 3D supramolecular network. Complex 3 displays a 3D coordination network with a 6-connected (4{sup 12}.6{sup 3}) topology based on 2D [Co{sub 2}(1,4-NDC){sub 2}]{sub n} layers and bidentate 3-bpcb bridging ligands. The influences of different bis-pyridyl-bis-amide ligands with various spacers on the structures of title complexes are studied. Moreover, the fluorescent properties, electrochemical behaviors and magnetic properties of complexes 1–3 have been investigated. - Graphical abstract: Three multifunctional cobalt(II) complexes constructed from three bis-pyridyl-bis-amide and 1,4-naphthalenedicarboxylic acid have been hydrothermally synthesized and characterized. The fluorescent, electrochemical and magnetic properties of 1–3 have been investigated. - Highlights: • Three multifunctional cobalt(II) complexes based on various bis-pyridyl-bis-amide ligands. • Complex 1 is a 3D coordination structure with 8-connected (4{sup 20}.6{sup 8

  14. Part I. Synthesis and applications of molecular sieves. Part II. The effect of temperature and support in reduction of cobalt oxide: An in situ XRD study

    NASA Astrophysics Data System (ADS)

    Garces Trujillo, Luis Javier

    Part I. Alkylation of aniline (PhNH2) with methanol (MeOH) over co-crystallized zeolite RHO-Zeolite X (FAU) and over zeolite Linde Type L (Sr,K-LTL) as catalysts has been studied. Co-crystallized zeolite RHO-Zeolite X (FAU) favors the formation of N,N-dimethylaniline (NNDMA), with high selectivity >90%, having an advantage over pure zeolite X(FAU) of staying active even after 10 h of reaction. Activity of co-crystallized RHO-Zeolite X (FAU) is higher than that for Sr,K-LTL in terms of production of NNDMA. Octahedral molecular sieves (OMS-2) have been reported as catalysts for oxidation reactions. Effects of using polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) in the synthesis of OMS-2 have been studied. Structure of OMS-2 was kept when PVA or PVP were used as indicated by XRD and FTIR data. PVA and PVP were useful to improve the film hardness of OMS-2 applied on glass surfaces as measured by the pencil hardness test, and Knoop microhardness test. By using PVA or PVP as non-chelating agents, an increase in surface area from 59 (m2/g) to 114 (m2/g), a decrease in particle size, from 29.8 nm to 12.1 nm, and a hardness value of 4H using the pencil hardness test, and 17.73 HK by Knoops micro hardness tests for OMS-2 prepared with PVA were observed. ZK-5 (KFI) molecular sieve was synthesized in the K2O: SrO: Al2O3: SiO2: 160 H2O: THF system using conventional hydrothermal heating. Products were characterized by XRD, TGA, FESEM, EDX and TPD-MS. Molar ratios of THF/Al2O3 from 0.4 to 1.0 gives best results in terms of crystallinity and purity for the prepared ZK-5. Part II. Reduction of cobalt oxide (Co 3O4) at different temperatures and in combination with different modifiers and supported on gamma-Al2O3 was monitored by in situ X-ray diffraction. Complete reduction of cobalt oxide to the (hcp) phase is observed at 250°C. Different reduction sequence can give different results in terms of crystalline phase obtained for cobalt even if the same maximum reduction

  15. Cobalt poisoning

    MedlinePlus

    ... the wear and tear of some cobalt/chromium metal-on-metal hip implants. This type of implant is an ... hip socket that is created by fitting a metal ball into a metal cup. Sometimes, metal particles ( ...

  16. The investigation of the solvent effect on coordination of nicotinato ligand with cobalt(II) complex containing tris(2-benzimidazolylmethyl)amine: A computational study

    NASA Astrophysics Data System (ADS)

    Sayin, Koray; Karakaş, Duran

    2014-11-01

    The electronic structure of [Co(ntb)(nic)]+ complex ion are optimized by using density functional theory (DFT) method with mix basis set. Where (ntb) represents tris(2-benzimidazolylmethyl)amine ligand and (nic) is the anion of nicotinic acids. Six different fields, vacuum, chloroform, butanonitrile, methanol, water and formamide solvents are used in these calculations. The calculated structural parameters indicate that (nic) ligand coordinates to cobalt(II) containing (ntb) ligand with one oxygen atom in butanonitrile, methanol, water and formamide solvents but coordinates with two oxygen atoms in vacuum. These results are supported with IR, UV and 1H NMR spectra. According to the calculated results, the geometry of [Co(ntb)(nic)]+ complex ion is distorted octahedral in vacuum while the geometry is distorted square pyramidal in the all other solvents. Distorted octahedral [Co(ntb)(nic)]+ complex ion have not been synthesized as experimentally and it is predicted with computational chemistry methods.

  17. Studies on the Interaction Mechanism of 1,10-Phenanthroline Cobalt(II) Complex with DNA and Preparation of Electrochemical DNA Biosensor

    PubMed Central

    Niu, Shuyan; Li, Feng; Zhang, Shusheng; Wang, Long; Li, Xuemei; Wang, Shiying

    2006-01-01

    Fluorescence spectroscopy and ultraviolet (UV) spectroscopy techniques coupled with cyclic voltammetry (CV) were used to study the interaction between salmon sperm DNA and 1,10-Phenanthroline cobalt(II) complex, [Co(phen)2(Cl)(H2O)]Cl·H2O, where phen = 1,10-phenanthroline. The interaction between [Co(phen)2(Cl)(H2O)]+ and double-strand DNA (dsDNA) was identified to be intercalative mode. An electrochemical DNA biosensor was developed by covalent immobilization of probe single-strand DNA (ssDNA) related to human immunodeficiency virus (HIV) on the activated glassy carbon electrode (GCE). With [Co(phen)2(Cl)(H2O)]+ being the novel electrochemical hybridization indicator, the selectivity of ssDNA-modified electrode was investigated and selective detection of complementary ssDNA was achieved using differential pulse voltammetry (DPV).

  18. Growth mechanism of Cobalt(II) Phthalocyanine(CoPc) thin films on SiO{sub 2} and muscovite substrates

    SciTech Connect

    Gedda, Murali; Subbarao, Nimmakayala V. V.; Goswami, Dipak K.

    2014-01-28

    Thin films of Cobalt(II) Phthalocyanine (CoPc) were grown by thermal evaporation technique on two different substrates namely SiO{sub 2} and atomically cleaned muscovite mica(001) at various substrate temperatures. Deposition rate has been maintained to 0.3Å/sec during the growth of the films. The growth process is studied by means of atomic force microscopy (AFM). Films on SiO{sub 2} exhibit only three-dimensional islands and uniformity of these islands improved with substrate temperatures, whereas films on mica (001) consist of long oriented percolated structures. The results revealed that the growth mechanism of CoPc strongly depends on substrate temperatures as well as nature of substrate used. Optical properties were characterized by UV-Visible spectroscopy and structural properties were studied using X-ray diffraction.

  19. Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy

    DOE PAGES

    Chen, Lei; Cui, Hui-Hui; Stavretis, Shelby E.; ...

    2016-12-07

    We synthesized and studied three mononuclear cobalt(II) tetranitrate complexes (A)2[Co(NO3)4] with different countercations, Ph4P+ (1), MePh3P+ (2), and Ph4As+ (3), using X-ray single-crystal diffraction, magnetic measurements, inelastic neutron scattering (INS), high-frequency and high-field EPR (HF-EPR) spectroscopy, and theoretical calculations. Furthermore, the X-ray diffraction studies reveal that the structure of the tetranitrate cobalt anion varies with the countercation. 1 and 2 exhibit highly irregular seven-coordinate geometries, while the central Co(II) ion of 3 is in a distorted-dodecahedral configuration. The sole magnetic transition observed in the INS spectroscopy of 1–3 corresponds to the zero-field splitting (2(D2 + 3E2)1/2) from 22.5(2) cm–1 inmore » 1 to 26.6(3) cm–1 in 2 and 11.1(5) cm–1 in 3. The positive sign of the D value, and hence the easy-plane magnetic anisotropy, was demonstrated for 1 by INS studies under magnetic fields and HF-EPR spectroscopy. The combined analyses of INS and HF-EPR data yield the D values as +10.90(3), +12.74(3), and +4.50(3) cm–1 for 1–3, respectively. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal the slow magnetization relaxation in 1 and 2 at an applied dc field of 600 Oe, which is a characteristic of field-induced single-molecule magnets (SMMs). Finally, the electronic structures and the origin of magnetic anisotropy of 1–3 were revealed by calculations at the CASPT2/NEVPT2 level.« less

  20. Series of Hydrated Heterometallic Uranyl-Cobalt(II) Coordination Polymers with Aromatic Polycarboxylate Ligands: Formation of U═O-Co Bonding upon Dehydration Process.

    PubMed

    Falaise, Clément; Delille, Jason; Volkringer, Christophe; Vezin, Hervé; Rabu, Pierre; Loiseau, Thierry

    2016-10-06

    Five new heterometallic UO2(2+)-Co(2+) coordination polymers have been obtained by hydrothermal reactions of uranyl nitrate and metallic cobalt with aromatic polycarboxylic acids. Single-crystal X-ray diffraction reveals the formation of four 3D frameworks with the mellitate (noted mel) ligand and one 2D network with the isophthalate (noted iso) ligand. The compounds [(UO2(H2O))2Co(H2O)4(mel)]·4H2O (1), [UO2Co(H2O)4(H2mel)]·2H2O (2), and [(UO2(H2O))2Co(H2O)4(mel)] (4) consist of 3D frameworks built up from the connection of mellitate ligands and mononuclear metallic centers. These three compounds exhibit two types of geometry for the uranyl cation: pentagonal bipyramidal environment for 1 and 4, and hexagonal bipyramidal environment for 2. Using the mellitate ligand, the uranyl dinuclear unit is isolated in the compound [(UO2)2(OH)2(Co(H2O)4)2(mel)]·2H2O (3). Due to their 2D framework and the presence of uncoordinated cobalt(II) cations, the compound [(UO2)(iso)3][Co(H2O)6]·3(H2O) (5) is drastically different than the previous one. The thermal behavior of compounds 1, 2, and 3 has been studied by thermogravimetric analysis, X-ray thermodiffraction, and in situ infrared. By heating, the dehydration of compounds 1 and 2 promotes two structural transitions (1 → 1' and 2 → 2'). The crystal structures of [(UO2(H2O))2Co(H2O)2(mel)] (1') and [(UO2)Co(H2mel)] (2') were determined by single-crystal X-ray diffraction; each of them presents a heterometallic interaction between uranyl bond and the Co(II) center. Due to the rarely reported coordination environment for the cobalt center in compound 2' (square pyramidal configuration), the magnetic properties and EPR characterizations of the compounds 2 and 2' were also investigated.

  1. Synthesis, crystal structure, antibacterial activity and theoretical studies on a novel mononuclear cobalt(II) complex based on 2,4,6-tris(2-pyridyl)-1,3,5-triazine ligand

    NASA Astrophysics Data System (ADS)

    Maghami, Mahboobeh; Farzaneh, Faezeh; Simpson, Jim; Ghiasi, Mina; Azarkish, Mohammad

    2015-08-01

    A cobalt complex was prepared from CoCl2·6H2O and 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) in methanol and designated as [Co(tptz)(CH3OH)Cl2]·CH3OH·0.5H2O (1). It was characterized by several techniques including TGA analysis and FT-IR, UV-Vis and 1H NMR spectral studies. The crystal structure of 1 was determined by single-crystal X-ray diffraction. The Co(II) metal center in 1 is six coordinated with a distorted octahedral geometry. The tptz ligand is tridentate and coordinates to the cobalt through coplanar nitrogen atoms from the triazine and two pyridyl rings. Two chloride anions and a methanol molecule complete the inner coordination sphere of the metal ion. The optimized geometrical parameters obtained by DFT calculation are in good agreement with single XRD data. The in vitro antibacterial activity of various tptz complexes of Co(II), Ni(II), Cu(II), Mn(II) and Rh(III) were evaluated against Gram-positive (Bacillus subtilis, Staphylococcus aureus and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Whereas all complexes exhibited good activity in comparison to standard antibacterial drugs, the inhibitory effects of complexes were found to be more than that of the parent ligand. Overall, the obtained results strongly suggest that the cobalt(II) complex is a suitable candidate for counteracting antibiotic resistant microorganisms.

  2. Synthesis, physico-chemical studies of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes with some p-substituted acetophenone benzoylhydrazones and their antimicrobial activity.

    PubMed

    Singh, Vinod P; Singh, Shweta; Katiyar, Anshu

    2009-04-01

    Complexes of the type [M(pabh)(H2O)Cl], [M(pcbh)(H2O)Cl] and [M(Hpabh)(H2O)2 (SO4)] where, M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); Hpabh = p-amino acetophenone benzoyl hydrazone and Hpcbh = p-chloro acetophenone benzoyl hydrazone have been synthesized and characterized with the help of elemental analyses, electrical conductance, magnetic susceptibility measurements, electronic, ESR and IR spectra, thermal (TGA & DTA) and X-ray diffraction studies. Co(II), Ni(II) and Cu(II) chloride complexes are square planar, whereas their sulfate complexes have spin-free octahedral geometry. ESR spectra of Cu(II) complexes with Hpabh are axial and suggest d(x(2)-y(2) as the ground state. The ligand is bidentate bonding through > C = N--and deprotonated enolate group in all the chloro complexes, whereas, >C = N and >C = O groups in all the sulfato complexes. Thermal studies (TGA & DTA) on [Cu(Hpabh)(H2O)2(SO4)] indicate a multistep decomposition pattern, which are both exothermic and endothermic in nature. X-ray powder diffraction parameters for [Co(pabh)(H2O)Cl] and [Ni(Hpabh)(H2O)2(SO4)] correspond to tetragonal and orthorhombic crystal lattices, respectively. The ligands as well as their complexes show a significant antifungal and antibacterial activity. The metal complexes are more active than the ligand.

  3. Cobalt(II) complexation with small biomolecules as studied by 57Co emission Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Kamnev, Alexander A.; Perfiliev, Yurii D.; Kulikov, Leonid A.; Tugarova, Anna V.; Kovács, Krisztina; Homonnay, Zoltán; Kuzmann, Ernő

    2017-02-01

    In the emission (57Co) variant of Mössbauer spectroscopy (EMS), the 57Co radionuclide (with a half-life of 9 months) is used that undergoes a nuclear decay 57Co → 57Fe via electron capture followed by the emission of a γ-quantum, the energy of which is modified by the chemical state and the close coordination environment of the parent 57Co atom. While EMS has been used largely in materials science and nuclear chemistry, its high sensitivity can also be of great advantage in revealing fine structural features and for speciation analysis of biological complexes, whenever the 57Co2 + cation can be used directly as the coordinating metal or as a substitute for native cobalt or other metal ions. As such EMS applications are yet rare, in order to reliably interpret emission spectra of sophisticated 57Co2 +-doped biosystems, model EMS studies of simple cobalt biocomplexes are necessary. In this work, EMS spectroscopic data are analysed and discussed for 57Co2 + complexes with a range of small biomolecules of different structures, including 4-n-hexylresorcinol, homoserine lactone and a few amino acids (spectra measured in rapidly frozen dilute aqueous solutions or in the dried state at T = 80 K). The EMS data obtained are discussed with regard to the available literature data related to the coordination modes of the biocomplexes under study.

  4. In vitro effects on Indium-111-Oxine labeled leukocytes functions of N-etilmycin

    SciTech Connect

    Iacovo, R.D.; Perna, M.; Esposito, G.; Polese, C.; Frizzi, L.

    1985-05-01

    In order to study in vitro chemotaxis, phagocytosis and bactericydal efficiencies of granulocytes (PMN) and monocytes (Mo) of cancer patients with solid tumours, the authors have undertaken the evaluation of a method of measuring PMN and Mo chemotaxis with modified Boyden chambers, using In-111-oxine. The tests were performed in order to evaluate the interference of N-etilmycin with leukocyte functions, a currently fashionable antibiotic used in the treatment of gram-negative infections. The results both compare well with the visual method and are objective. Cancer patients, disease-free for a minimum of one year, were compared and evidenced normal chemotaxis and normal controls. No difference between the two groups was found (20.46% of those tested). The addition of N-etilmy-cin (6..mu..g/ml) to PMN and Mo further decreased the chemotaxis from 20.46% to 16.07% (t=2.81, P=0.0102). The addition of 30..mu..g/ml further decreased the chemotaxis from the mean control values to 5.925% (t=4.55,P 1%). The use of N-etilmycin in disease-free cancer patients should be avoided in the possible event of tumour enhancement.

  5. Endothelial cell labeling with indium-111-oxine as a marker of cell attachment to bioprosthetic surfaces

    SciTech Connect

    Sharefkin, J.B.; Lather, C.; Smith, M.; Rich, N.M.

    1983-03-01

    Canine vascular endothelium labeled with indium-111-oxine was used as a marker of cell attachment to vascular prosthetic surfaces with complex textures. Primarily cultured and freshly harvested endothelial cells both took up the label rapidly. An average of 72% of a 32 micro Ci labeling dose was taken up by 1.5 X 10(6) cells in 10 min in serum-free medium. Over 95% of freshly labeled cells were viable by trypan blue tests and only 5% of the label was released after 1 h incubations at 37 degrees C. Labeled and unlabeled cells had similar rates of attachment to plastic dishes. Scanning electron microscopic studies showed that labeled cells retained their ability to spread on tissue culture dishes even at low (1%) serum levels. Labeled endothelial cells seeded onto Dacron or expanded polytetrafluoroethylene vascular prostheses by methods used in current surgical models could be identified by autoradiography of microscopic sections of the prostheses, and the efficiency of cell attachment to the prosthesis could be measured by gamma counting. Indium-111 labeling affords a simple and rapid way to measure initial cell attachment to, and distribution on, vascular prosthetic materials. The method could also allow measurement of early cell loss from a flow surface in vivo by using external gamma imaging.

  6. Anisotropic Fermi couplings due to large unquenched orbital angular momentum: Q-band (1)H, (14)N, and (11)B ENDOR of bis(trispyrazolylborate) cobalt(II).

    PubMed

    Myers, William K; Scholes, Charles P; Tierney, David L

    2009-08-05

    We report Q-band ENDOR of (1)H, (14)N, and (11)B at the g( parallel) extreme of the EPR spectrum of bis(trispyrazolylborate) cobalt(II) [Co(Tp)(2)] and two structural analogs. This trigonally symmetric, high-spin (hs) S = 3/2 Co(II) complex shows large unquenched ground-state orbital angular momentum, which leads to highly anisotropic electronic g-values (g( parallel) = 8.48, g( perpendicular) = 1.02). The large g-anisotropy is shown to result in large dipolar couplings near g( parallel) and uniquely anisotropic (14)N Fermi couplings, which arise from spin transferred to the nitrogen 2s orbital (2.2%) via antibonding interactions with singly occupied metal d(x(2)-y(2)) and d(z(2)) orbitals. Large, well-resolved (1)H and (11)B dipolar couplings were also observed. Taken in concert with our previous X-band ENDOR measurements at g( perpendicular) ( Myers, W. K.; et al. Inorg. Chem. 2008, 47, 6701-6710 ), the present data allow a detailed analysis of the dipolar hyperfine tensors of two of the four symmetry distinct protons in the parent molecule. In the substituted analogs, changes in hyperfine coupling due to altered metal-proton distances give further evidence of an anisotropic Fermi contact interaction. For the pyrazolyl 3H proton, the data indicate a 0.2 MHz anisotropic contact interaction and approximately 4% transfer of spin away from Co(II). Dipolar coupling also dominates for the axial boron atoms, consistent with their distance from the Co(II) ion, and resolved (11)B quadrupolar coupling showed approximately 30% electronic inequivalence between the B-H and B-C sp(3) bonds. This is the first comprehensive ENDOR study of any hs Co(II) species and lays the foundation for future development.

  7. [Suppression of activity of Candida albicans proteinases by cobalt chloride].

    PubMed

    Kutyreva, M P; Mukhametzianova, A R; Ulakhovich, N A

    2012-01-01

    Influence of cobalt (II) chloride on the system of Candida albicans proteinase (SAP C. alb.) (both in solution and immobilized on a surface of nitrocellulose membranes) has been investigated. In solution cobalt chloride inactivated inducible but not constitute enzyme. In the heterogenous sytem proteolitical effect of the cobalt ion on inductible proteinase was also observed.

  8. Cobalt superalloy

    SciTech Connect

    Crook, P.

    1983-11-15

    Disclosed is a cobalt-base superalloy containing about 32% cobalt, 8% nickel, 26.5% chromium, 2.5% tungsten, 5% niobium, about 1% each manganese and silicon, about 0.4% carbon, and the balance about 23% iron plus incidental impurities and modifiers normally found in alloys of this class. The alloy is readily processed in the form of wrought products, castings, metal powder and all forms of welding and hardfacing materials. The outstanding characteristics of the new alloy include the resistance to cavitation erosion and galling, low cost and minimal use of strategic metals.

  9. Cobalt (II) complex with novel unsymmetrical tetradentate Schiff base (ON) ligand: in vitro cytotoxicity studies of complex, interaction with DNA/protein, molecular docking studies, and antibacterial activity.

    PubMed

    Shokohi-Pour, Zahra; Chiniforoshan, Hossein; Sabzalian, Mohammad R; Esmaeili, Seyed-Alireza; Momtazi-Borojeni, Amir Abbas

    2017-03-08

    [C20H17N3O2] and cobalt (II) complex [Co(L(2))(MeOH)2].ClO4, (L(2) = 4-((E)-1-((2-(((E)-pyridin-2-ylmethylene) amino) phenyl) imino) ethyl) benzene-1, 3-diol) novel Schiff base has been synthesiszed and chracterized by Fourier transform infrared, UV-vis, (1)H-NMR spectroscopy, and elemental analysis techniques. The interaction of Co(II) complex with DNA and BSA was investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroism, and thermal denaturation studies. Our experiments indicate that this complex could strongly bind to CT-DNA via minor groove mechanism. In addition, fluorescence spectrometry of BSA with the complex showed that the fluorescence quenching mechanism of BSA was of static type. The complex exhibited significant in vitro cytotoxicity against three human cancer cell lines (JURKAT, SKOV3, and U87). The molecular docking experiment effectively proved the binding of complex to DNA and BSA. Finally, antibacterial assay over gram-positive and gram-negative pathogenic bacterial strains was studied.

  10. Through-space and through-bond mixed charge transfer mechanisms on the hydrazine oxidation by cobalt(II) phthalocyanine in the gas phase.

    PubMed

    Paredes-García, V; Cardenas-Jirón, G I; Venegas-Yazigi, D; Zagal, J H; Paez, M; Costamagna, J

    2005-02-17

    Two quantum chemistry theoretical models in the gas phase at the density functional theory B3LYP/LACVP(d) level of calculation are proposed to rationalize the hydrazine oxidation by cobalt(II) phthalocyanine (Co(II)Pc). This oxidation reaction involves the net transfer of four electrons. These theoretical models that are described in terms of energy profiles include a through-space mechanism for the transfer of the first electron of the hydrazine and a through-bond mechanism proposed for the transfer of the three electrons remaining. The main difference between both models arises from a one-electron and one-proton alternate transfer for model 1 and a two-electron and two-proton alternate transfer for model 2. The main problem for experimental studies is to determine if the first transfer corresponds to an electron or a chemical transfer. Under this point of view, we proposed two models which deal with this problem. We conclude that model 1 is more reasonable than model 2 because the whole oxidation process is always exergonic.

  11. Concentration of In-111-oxine-labeled autologous leukocytes in noninfected and nonrejecting renal allografts: concise communication

    SciTech Connect

    Collier, B.D.; Isitman, A.T.; Kaufman, H.M.; Rao, S.A.; Knobel, J.; Hellman, R.S.; Zielonka, J.S.; Pelc, L.

    1984-02-01

    Autologous leukocytes labeled with In-111 oxine (ILL) concentrated in the renal allografts of eight patients for whom transplant rejection, infection, or acute tubular necrosis (ATN) could be excluded. All patients had good-to-adequate renal function at the time of ILL scintigraphy, and none developed rejection or renal transplant failure during a 1-mo follow-up period. It is concluded that normally functioning renal allografts without evidence of rejection, infection, or ATN often will concentrate ILL. When a baseline study is not available for comparison, this phenomenon limits the value of ILL scintigraphy as a diagnostic test for transplant rejection or infection.

  12. The feed forward neural network model for liquid-liquid extraction and separation of cobalt (II) from sodium acetate media using cyanex 272

    NASA Astrophysics Data System (ADS)

    Sudibyo, Aji, B. B.; Priyanto, S.

    2017-03-01

    Cobalt is one of the precious ferromagnetic metals, which widely used in the preparation of magnetic, wear-resistant and high-strength alloys. This metal was not found naturally in single metal form but is found as impurities in nickel or copper ore. The extraction process is one of the methods to separate cobalt from its impurities. However, this process needs an expensive organic solution. In practice, changing the composition of chemicals composition in extraction process always affect at a high cost. Therefore, the development of the artificial neural network (ANN) model to model the cobalt extraction process can serve as an important tool for predicting and investigating the optimum production for the cobalt extraction without the need to run the actual experiment. Hence, the development of the ANN model of cobalt extraction model is essential to simulate the process, which can lead to high yields of cobalt production. In this work a selected optimum multiple-input-single-output (MISO) model of feed forward neural network (FFNN) was used to predict the percentage of cobalt extraction. MISO FFNN with 20, 30 and 50 hidden nodes were used to simulate cobalt extraction process. The simulation results achieved was compared with data available in the literature. The results show that MISO FFNN with 50 hidden nodes has the best performance. The optimum result of MISO FFNN then exported to Simulink model in Matlab environment, hence make it easy to use in predicting and investigating for the optimum production of the cobalt extraction.

  13. Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy

    SciTech Connect

    Chen, Lei; Cui, Hui-Hui; Stavretis, Shelby E.; Hunter, Seth C.; Zhang, Yi-Quan; Chen, Xue-Tai; Sun, Yi-Chen; Wang, Zhenxing; Song, You; Podlesnyak, Andrey A.; Ouyang, Zhong-Wen; Xue, Zi-Ling

    2016-12-07

    We synthesized and studied three mononuclear cobalt(II) tetranitrate complexes (A)2[Co(NO3)4] with different countercations, Ph4P+ (1), MePh3P+ (2), and Ph4As+ (3), using X-ray single-crystal diffraction, magnetic measurements, inelastic neutron scattering (INS), high-frequency and high-field EPR (HF-EPR) spectroscopy, and theoretical calculations. Furthermore, the X-ray diffraction studies reveal that the structure of the tetranitrate cobalt anion varies with the countercation. 1 and 2 exhibit highly irregular seven-coordinate geometries, while the central Co(II) ion of 3 is in a distorted-dodecahedral configuration. The sole magnetic transition observed in the INS spectroscopy of 1–3 corresponds to the zero-field splitting (2(D2 + 3E2)1/2) from 22.5(2) cm–1 in 1 to 26.6(3) cm–1 in 2 and 11.1(5) cm–1 in 3. The positive sign of the D value, and hence the easy-plane magnetic anisotropy, was demonstrated for 1 by INS studies under magnetic fields and HF-EPR spectroscopy. The combined analyses of INS and HF-EPR data yield the D values as +10.90(3), +12.74(3), and +4.50(3) cm–1 for 1–3, respectively. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal the slow magnetization relaxation in 1 and 2 at an applied dc field of 600 Oe, which is a characteristic of field-induced single-molecule magnets (SMMs). Finally, the electronic structures and the origin of magnetic anisotropy of 1–3 were revealed by calculations at the CASPT2/NEVPT2 level.

  14. Cobalt(II) chloride complexes with 1,1'-dimethyl-4,4'-bipyrazole featuring first- and second-sphere coordination of the ligand.

    PubMed

    Domasevitch, Konstantin V

    2014-03-01

    In catena-poly[[dichloridocobalt(II)]-μ-(1,1'-dimethyl-4,4'-bipyrazole-κ(2)N(2):N(2'))], [CoCl2(C8H10N4)]n, (1), two independent bipyrazole ligands (Me2bpz) are situated across centres of inversion and in tetraaquabis(1,1'-dimethyl-4,4'-bipyrazole-κN(2))cobalt(II) dichloride-1,1'-dimethyl-4,4'-bipyrazole-water (1/2/2), [Co(C8H10N4)2(H2O)4]Cl2·2C8H10N4·2H2O, (2), the Co(2+) cation lies on an inversion centre and two noncoordinated Me2bpz molecules are also situated across centres of inversion. The compounds are the first complexes involving N,N'-disubstituted 4,4'-bipyrazole tectons. They reveal a relatively poor coordination ability of the ligand, resulting in a Co-pyrazole coordination ratio of only 1:2. Compound (1) adopts a zigzag chain structure with bitopic Me2bpz links between tetrahedral Co(II) ions. Interchain interactions occur by means of very weak C-H...Cl hydrogen bonding. Complex (2) comprises discrete octahedral trans-[Co(Me2bpz)2(H2O)4](2+) cations formed by monodentate Me2bpz ligands. Two equivalents of additional noncoordinated Me2bpz tectons are important as `second-sphere ligands' connecting the cations by means of relatively strong O-H...N hydrogen bonding with generation of doubly interpenetrated pcu (α-Po) frameworks. Noncoordinated chloride anions and solvent water molecules afford hydrogen-bonded [(Cl(-))2(H2O)2] rhombs, which establish topological links between the above frameworks, producing a rare eight-coordinated uninodal net of {4(24).5.6(3)} (ilc) topology.

  15. Anti-oxidant, in vitro, in vivo anti-inflammatory activity and antiproliferative activity of mefenamic acid and its metal complexes with manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II).

    PubMed

    Kovala-Demertzi, Dimitra; Hadjipavlou-Litina, Dimitra; Staninska, Malgorzata; Primikiri, Alexandra; Kotoglou, Chronis; Demertzis, Mavroudis A

    2009-06-01

    Some new complexes of mefenamic acid with potentially interesting biological activity are described. The complexes of mefenamic acid [Mn(mef)(2)(H(2)O)(2)], 1, [Co(mef)(2)(H(2)O)(2)], 2, [Ni(mef)(2)(H(2)O)(2)], 3, [Cu(mef)(2)(H(2)O)](2), 4 and [Zn(mef)(2)], 5, were prepared by the reaction of mefenamic acid, a potent anti-inflammatory drug with metal salts. Optical and infrared spectral data of these new complexes are reported. Monomeric six-coordinated species were isolated in the solid state for Mn(II), Ni(II) and Co(II), dimeric five-coordinated for Cu(II) and monomeric four-coordinated for Zn(II). In DMF or CHCl(3) solution the coordination number is retained and the coordinated molecules of water are replaced by solvent molecules. The anti-oxidant properties of the complexes were evaluated using the 1,1-diphenyl-2-picrylhydrazyl, DPPH, free radical scavenging assay. The scavenging activities of the complexes were measured and compared with those of the free drug and vitamin C. We have explored their ability to inhibit soybean lipoxygenase, beta-glucuronidase and trypsin- induced proteolysis. The complex [Mn(mef)(2)(H(2)O)(2)] exhibits the highest antioxidant activity and the highest inhibitory effect against the soybean lipogygenase (LOX), properties that are not demonstrated by mefenamic acid. Their inhibitory effects on rat paw edema induced by Carrageenan was studied and compared with those of mefenamic acid. The complex [Zn(mef)(2)] exhibited a strong inhibitory effect at 0.1 mmol/Kg B.W. (81.5 +/- 1.3% inhibition), superior to the inhibition induced by mefenamic acid at the same dose (61.5 +/- 2.3% inhibition). Mefenamic acid and its metal complexes have been evaluated for antiproliferative activity in vitro against the cells of three human cancer cell lines: MCF-7 (human breast cancer cell line), T24 (bladder cancer cell line), A-549 (non-small cell lung carcinoma) and a mouse fibroblast L-929 cell line. The copper(II) complex displays against T24, MCF-7

  16. Nickel acts as an adjuvant during cobalt sensitization.

    PubMed

    Bonefeld, Charlotte Menné; Nielsen, Morten Milek; Vennegaard, Marie T; Johansen, Jeanne Duus; Geisler, Carsten; Thyssen, Jacob P

    2015-03-01

    Metal allergy is the most frequent form of contact allergy with nickel and cobalt being the main culprits. Typically, exposure comes from metal-alloys where nickel and cobalt co-exist. Importantly, very little is known about how co-exposure to nickel and cobalt affects the immune system. We investigated these effects by using a recently developed mouse model. Mice were epicutaneously sensitized with i) nickel alone, ii) nickel in the presence of cobalt, iii) cobalt alone, or iv) cobalt in the presence of nickel, and then followed by challenge with either nickel or cobalt alone. We found that sensitization with nickel alone induced more local inflammation than cobalt alone as measured by increased ear-swelling. Furthermore, the presence of nickel during sensitization to cobalt led to a stronger challenge response to cobalt as seen by increased ear-swelling and increased B and T cell responses in the draining lymph nodes compared to mice sensitized with cobalt alone. In contrast, the presence of cobalt during nickel sensitization only induced an increased CD8(+) T cell proliferation during challenge to nickel. Thus, the presence of nickel during cobalt sensitization potentiated the challenge response against cobalt more than the presence of cobalt during sensitization to nickel affected the challenge response against nickel. Taken together, our study demonstrates that sensitization with a mixture of nickel and cobalt leads to an increased immune response to both nickel and cobalt, especially to cobalt, and furthermore that the adjuvant effect appears to correlate with the inflammatory properties of the allergen.

  17. Chemometrics-assisted simultaneous determination of cobalt(II) and chromium(III) with flow-injection chemiluminescence method

    NASA Astrophysics Data System (ADS)

    Li, Baoxin; Wang, Dongmei; Lv, Jiagen; Zhang, Zhujun

    2006-09-01

    In this paper, a flow-injection chemiluminescence (CL) system is proposed for simultaneous determination of Co(II) and Cr(III) with partial least squares calibration. This method is based on the fact that both Co(II) and Cr(III) catalyze the luminol-H 2O 2 CL reaction, and that their catalytic activities are significantly different on the same reaction condition. The CL intensity of Co(II) and Cr(III) was measured and recorded at different pH of reaction medium, and the obtained data were processed by the chemometric approach of partial least squares. The experimental calibration set was composed with nine sample solutions using orthogonal calibration design for two component mixtures. The calibration curve was linear over the concentration range of 2 × 10 -7 to 8 × 10 -10 and 2 × 10 -6 to 4 × 10 -9 g/ml for Co(II) and Cr(III), respectively. The proposed method offers the potential advantages of high sensitivity, simplicity and rapidity for Co(II) and Cr(III) determination, and was successfully applied to the simultaneous determination of both analytes in real water sample.

  18. Comparative cytotoxicity and genotoxicity of cobalt (II, III) oxide, iron (III) oxide, silicon dioxide, and aluminum oxide nanoparticles on human lymphocytes in vitro.

    PubMed

    Rajiv, S; Jerobin, J; Saranya, V; Nainawat, M; Sharma, A; Makwana, P; Gayathri, C; Bharath, L; Singh, M; Kumar, M; Mukherjee, A; Chandrasekaran, N

    2016-02-01

    Despite the extensive use of nanoparticles (NPs) in various fields, adequate knowledge of human health risk and potential toxicity is still lacking. The human lymphocytes play a major role in the immune system, and it can alter the antioxidant level when exposed to NPs. Identification of the hazardous NPs was done using in vitro toxicity tests and this study mainly focuses on the comparative in vitro cytotoxicity and genotoxicity of four different NPs including cobalt (II, III) oxide (Co3O4), iron (III) oxide (Fe2O3), silicon dioxide (SiO2), and aluminum oxide (Al2O3) on human lymphocytes. The Co3O4 NPs showed decrease in cellular viability and increase in cell membrane damage followed by Fe2O3, SiO2, and Al2O3 NPs in a dose-dependent manner after 24 h of exposure to human lymphocytes. The oxidative stress was evidenced in human lymphocytes by the induction of reactive oxygen species, lipid peroxidation, and depletion of catalase, reduced glutathione, and superoxide dismutase. The Al2O3 NPs showed the least DNA damage when compared with all the other NPs. Chromosomal aberration was observed at 100 µg/ml when exposed to Co3O4 NPs and Fe2O3 NPs. The alteration in the level of antioxidant caused DNA damage and chromosomal aberration in human lymphocytes.

  19. Synthesis, structure and magnetic properties of Na 9Co 2O 7, a new mixed-valent sodium cobaltate(II,III)

    NASA Astrophysics Data System (ADS)

    Sofin, M.; Peters, E.-M.; Jansen, M.

    2004-04-01

    Na 9Co 2O 7 was prepared via the azide/nitrate route. Stoichiometric mixtures of the precursors (Co 3O 4, NaN 3 and NaNO 3) were heated in a special regime up to 450 °C and annealed at this temperature for 100 h in specially designed silver containers. Single crystals have been grown by annealing a Na 2O/Na 9Co 2O 7 mixture (molar ratio 1:2) at 500 °C for 2000 h in silver crucibles, which were sealed in glass ampoules under dried Ar. According to the X-ray analysis of the crystal structure ( Pca2 1, Z=4, a=9.5477(6) Å, b=9.9040(6) Å, c=10.1919(7) Å, 4103 independent reflections, R1=5.23% (all data)) there are isolated Co IIIO 4 tetrahedra and Co IIO 3 triangles. Na 9Co 2O 7 is isostructural to Na 9Fe 2O 7, and shows Curie-Weiss behaviour down to ˜25 K. The best fit (for Co II ( S=3/2) and Co III ( S=2)) yields an average value of the magnetic moment (per cobalt) μ=3.23 μB ( g=2.07) and Θ=-6 K. At 20 K one observes an onset of ferromagnetic order.

  20. Spectrophotometric determination of some anti-tussive and anti-spasmodic drugs through ion-pair complex formation with thiocyanate and cobalt(II) or molybdenum(V)

    NASA Astrophysics Data System (ADS)

    El-Shiekh, Ragaa; Zahran, Faten; El-Fetouh Gouda, Ayman Abou

    2007-04-01

    Two rapid, simple and sensitive extractive specrophotometric methods has been developed for the determination of anti-tussive drugs, e.g., dextromethorphan hydrobromide (DEX) and pipazethate hydrochloride (PiCl) and anti-spasmodic drugs, e.g., drotaverine hydrochloride (DvCl) and trimebutine maleate (TM) in bulk and in their pharmaceutical formulations. The proposed methods depend upon the reaction of cobalt(II)-thiocyanate (method A) and molybdenum(V)-thiocyanate ions (method B) with the cited drugs to form stable ion-pair complexes which extractable with an n-butnol-dichloromethane solvent mixture (3.5:6.5) and methylene chloride for methods A and B, respectively. The blue and orange red color complexes are determined either colorimetrically at λmax 625 nm (using method A) and 467 or 470 nm for (DEX and PiCl) or (DvCl and TM), respectively (using method B). The concentration range is 20-400 and 2.5-50 μg mL -1 for methods A and B, respectively. The proposed method was successfully applied for the determination of the studied drugs in pure and in pharmaceutical formulations applying the standard additions technique and the results obtained in good agreement well with those obtained by the official method.

  1. Spectrophotometric determination of some anti-tussive and anti-spasmodic drugs through ion-pair complex formation with thiocyanate and cobalt(II) or molybdenum(V).

    PubMed

    El-Shiekh, Ragaa; Zahran, Faten; El-Fetouh Gouda, Ayman Abou

    2007-04-01

    Two rapid, simple and sensitive extractive specrophotometric methods has been developed for the determination of anti-tussive drugs, e.g., dextromethorphan hydrobromide (DEX) and pipazethate hydrochloride (PiCl) and anti-spasmodic drugs, e.g., drotaverine hydrochloride (DvCl) and trimebutine maleate (TM) in bulk and in their pharmaceutical formulations. The proposed methods depend upon the reaction of cobalt(II)-thiocyanate (method A) and molybdenum(V)-thiocyanate ions (method B) with the cited drugs to form stable ion-pair complexes which extractable with an n-butnol-dichloromethane solvent mixture (3.5:6.5) and methylene chloride for methods A and B, respectively. The blue and orange red color complexes are determined either colorimetrically at lambdamax 625 nm (using method A) and 467 or 470 nm for (DEX and PiCl) or (DvCl and TM), respectively (using method B). The concentration range is 20-400 and 2.5-50 microg mL-1 for methods A and B, respectively. The proposed method was successfully applied for the determination of the studied drugs in pure and in pharmaceutical formulations applying the standard additions technique and the results obtained in good agreement well with those obtained by the official method.

  2. Synthesis, characterization, antimicrobial activity and carbonic anhydrase enzyme inhibitor effects of salicilaldehyde-N-methyl p-toluenesulfonylhydrazone and its Palladium(II), Cobalt(II) complexes

    NASA Astrophysics Data System (ADS)

    Alyar, Saliha; Adem, Şevki

    2014-10-01

    We report the synthesis of the ligand, salicilaldehyde-N-methyl p-toluenesulfonylhydrazone (salptsmh) derived from p-toluenesulfonicacid-1-methylhydrazide (ptsmh) and its Pd(II) and Co(II) metal complexes were synthesized for the first time. The structure of the ligand and their complexes were investigated using elemental analysis, magnetic susceptibility, molar conductance and spectral (IR, NMR and LC-MS) measurements. Salptsmh has also been characterized by single crystal X-ray diffraction. 1H and 13C shielding tensors for crystal structure were calculated with GIAO/DFT/B3LYP/6-311++G(d,p) methods in CDCl3. The complexes were found to have general composition [ML2]. The results of elemental analysis showed 1:2 (metal/ligand) stoichiometry for all the complex. Magnetic and spectral data indicate a square planar geometry for Pd(II) complex and a distorted tetrahedral geometry for Co(II) complexes. The ligand and its metal chelates have been screened for their antimicrobial activities using the disk diffusion method against the selected Gram positive bacteria: Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Enterococcus faecalis, Gram negative bacteria: Eschericha coli, Pseudomonas aeruginosa, Klebsiella pneumonia. The inhibition activities of these compounds on carbonic anhydrase II (CA II) and carbonic anhydrase I (CA I) have been investigated by comparing IC50 and Ki values and it has been found that Pd(II) complex have more enzyme inhibition efficiency than salptsmh and Co(II) complex.

  3. Reversible guest exchange and ferrimagnetism (T(C) = 60.5 K) in a porous cobalt(II)-hydroxide layer structure pillared with trans-1,4-cyclohexanedicarboxylate.

    PubMed

    Kurmoo, Mohamedally; Kumagai, Hitoshi; Hughes, Suzanne M; Kepert, Cameron J

    2003-10-20

    The synthesis, characterization, and reversible guest-exchange chemistry of a new porous magnetic material that orders ferrimagnetically at 60.5 K are described. The material, Co(5)(OH)(8)(chdc).4H(2)O (chdc = trans-1,4-cyclohexanedicarboxylate), contains tetrahedral-octahedral-tetrahedral Co(II)-hydroxide layers of composition Co((oct))(3)Co((tet))(2)(OH)(8) that are linked together by bis(unidentate) chdc pillars. Noncoordinated water molecules occupy 1-D channels situated between the chdc pillars. The material remains monocrystalline during dehydration from Co(5)(OH)(8)(chdc).4H(2)O (CDCC.4H(2)O) to Co(5)(OH)(8)(chdc) (CDCC) via an intermediate Co(5)(OH)(8)(chdc).2H(2)O (CDCC.2H(2)O) upon heating or evacuation. In-situ single crystal and powder X-ray diffraction analyses indicate that the interlayer spacing decreases in two steps, each corresponding to the loss of two water molecules per formula unit as determined by thermogravimetry. The single crystal structure of the fully dehydrated material, CDCC, has no void volume due to a tilting of the pillars and 9% decrease of the interlayer spacing with water removal. Exposure of CDCC to air causes rapid rehydration of this material to CDCC.4H(2)O, as determined by single crystal X-ray diffraction, powder X-ray diffraction, thermogravimetry, and vibrational spectroscopy. Both the hydrated and dehydrated forms order magnetically below 60.5 K. The susceptibility data are consistent with ferrimagnetic behavior, and the value of the saturation magnetization at 2 K (ca. 2 micro(B)) is explained by a model of two sublattices, one comprising three octahedral cobalt atoms and another comprising two tetrahedral cobalt atoms. There is an enhanced 2-D correlation within the layer at temperatures just above the Curie temperature, as seen by nonlinearity in the ac susceptibility data and remanence in the isothermal magnetization. The crossover from 2-D to 3-D ordering occurs at T(C). The large anisotropy in the magnetization data

  4. A cobalt(II) bis(salicylate)-based ionic liquid that shows thermoresponsive and selective water coordination

    SciTech Connect

    Kohno, Y; Cowan, MG; Masuda, M; Bhowmick, I; Shores, MP; Gin, DL; Noble, RD

    2014-01-01

    A metal-containing ionic liquid (MCIL) has been prepared in which the [CoII(salicylate)(2)](2-) anion is able to selectively coordinate two water molecules with a visible colour change, even in the presence of alcohols. Upon moderate heating or placement in vacuo, the hydrated MCIL undergoes reversible thermochromism by releasing the bound water molecules.

  5. Crystal structure and magnetic properties of two isomeric three-dimensional pyromellitate-containing cobalt(II) complexes.

    PubMed

    Fabelo, Oscar; Pasán, Jorge; Cañadillas-Delgado, Laura; Delgado, Fernando S; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

    2008-09-15

    The hydrothermal preparation, crystal structure determination, and magnetic study of two isomers made up of 1,2,4,5-benzenetetracarboxylate and high-spin Co(II) ions of formula [Co2(bta)(H2O)4]n x 2n H2O (1 and 2; H4bta = 1,2,4,5-benzenetetracarboxylic acid) are reported. 1 and 2 are three-dimensional compounds whose structures can be described as (4,4) rectangular layers of trans-diaquacobalt(II) units with the bta(4-) anion acting as tetrakis-monodentate ligand through the four carboxylate groups, which are further connected through other trans-[Co(H2O)2](2+) (1) and planar [Co(H2O)4](2+) (2) entities, with the bridging units being a carboxylate group in either the anti-syn (1) or syn-syn (2) conformations and a water molecule (2). The study of the magnetic properties of 1 and 2 in the temperature range 1.9-300 K shows the occurrence of weak antiferromagnetic interactions between the high-spin Co(II) ions, with the strong decrease of chi(M)T upon cooling being mainly due to the depopulation of the higher energy Kramers doublets of the six-coordinated Co(II) ions. The computed values of the exchange coupling between the Co(II) ions across anti-syn carboxylate (1) and syn-syn carboxylate/water (2) bridges are J = -0.060 (1) and -1.90 (2) cm(-1) (with the Hamiltonian being defined as H = -Jsigma(i,j)S(i) x S(j)). These values follow the different conformations of the carboxylate bridge in 1 (anti-syn) and 2 (syn-syn) with the occurrence of a double bridge in 2 (water/carboxylate).

  6. The renewable bismuth bulk annular band working electrode: fabrication and application in the adsorptive stripping voltammetric determination of nickel(II) and cobalt(II).

    PubMed

    Baś, Bogusław; Węgiel, Krystian; Jedlińska, Katarzyna

    2015-06-30

    The paper presents the first report on fabrication and application of a user friendly and mercury free electrochemical sensor, with the renewable bismuth bulk annular band working electrode (RBiABE), in stripping voltammetry (SV). The sensor body is partly filled with the internal electrolyte solution, in which the RBiABE is cleaned and activated before each measurement. Time of the RBiABE contact with the sample solution is precisely controlled. The usefulness of this sensor was tested by Ni(II) and Co(II) traces determination by means of differential pulse adsorptive stripping voltammetry (DP AdSV), after complexation with dimethylglyoxime (DMG) in ammonia buffer (pH 8.2). The experimental variables (composition of the supporting electrolyte, pre-concentration potential and time, potential of the RBiABE activation, and DP parameters), as well as possible interferences, were investigated. The linear calibration graphs for Ni(II) and Co(II), determined individually and together, in the range from 1×10(-8) to 70×10(-8)molL(-1) and from 1×10(-9) to 70×10(-9)molL(-1) respectively, were obtained. The calculated limit of detection (LOD), for 30s of the accumulation time, was 3×10(-9)molL(-1) for Ni(II) in case of a single element's analysis, whereas the LOD was 5×10(-9)molL(-1) for Ni(II) and 3×10(-10)molL(-1) for Co(II), when both metal ions were measured together. The repeatability of the Ni(II) and Co(II) adsorptive stripping voltammetric signals obtained at the RBiABE were equal to 5.4% and 2.5%, respectively (n=5). Finally, the proposed method was validated by determining Ni(II) and Co(II) in the certified reference waters (SPS-SW1 and SPS-SW2) with satisfactory results.

  7. Anisotropic Change in the Magnetic Susceptibility of a Dynamic Single Crystal of a Cobalt(II) Complex.

    PubMed

    Yao, Zi-Shuo; Wu, Shu-Qi; Kitagawa, Yasutaka; Su, Sheng-Qun; Huang, You-Gui; Li, Guo-Ling; Ni, Zhong-Hai; Nojiri, Hiroyuki; Shiota, Yoshihito; Yoshizawa, Kazunari; Kang, Soonchul; Kanegawa, Shinji; Sato, Osamu

    2017-01-16

    Atypically anisotropic and large changes in magnetic susceptibility, along with a change in crystalline shape, were observed in a Co(II) complex at near room temperature. This was achieved by combining oxalate molecules, acting as rotor, and a Co(II) ion with unquenched orbital angular momentum. A thermally controlled 90° rotation of the oxalate counter anion triggered a symmetry-breaking ferroelastic phase transition, accompanied by contraction-expansion behavior (ca. 4.5 %) along the long axis of a rod-like single crystal. The molecular rotation induced a minute variation in the coordination geometry around the Co(II) ion, resulting in an abrupt decrease and a remarkable increase in magnetic susceptibility along the direction perpendicular and parallel to the long axis of the crystal, respectively. Theoretical calculations suggested that such an unusual anisotropic change in magnetic susceptibility was due to a substantial reorientation of magnetic anisotropy induced by slight disruption in the ideal D3 coordination environment of the complex cation.

  8. Microwave Mapping Demonstration Using the Thermochromic Cobalt Chloride Equilibrium

    ERIC Educational Resources Information Center

    Nguyen, Vu D.; Birdwhistell, Kurt R.

    2014-01-01

    An update to the thermochromic cobalt(II) chloride equilibrium demonstration is described. Filter paper that has been saturated with aqueous cobalt(II) chloride is heated for seconds in a microwave oven, producing a color change. The resulting pink and blue map is used to colorfully demonstrate Le Châtelier's principle and to illuminate the…

  9. New complexes of cobalt(II) ions with pyridinecarboxylic acid N-oxides and 4,4‧-byp

    NASA Astrophysics Data System (ADS)

    Hnatejko, Zbigniew; Dutkiewicz, Grzegorz; Kubicki, Maciej; Lis, Stefan

    2013-02-01

    This paper reports a study concerning the isolation and characterization of mixed ligand complexes of the Co(II) ions with pyridinecarboxylic acids N-oxides (picolinic (PNO), nicotinic (NNO) and isonicotinic (INO)), [Co(PNO)2(4,4'-byp)]·6H2O 1, [Co(NNO)(4,4'-byp)NO3]·8H2O 2 and [Co(INO)(4,4'-byp)NO3]·7H2O 3; (4,4'-byp = 4,4'-bipyridine). The complexes 2 and 3 were prepared by the hydrothermal synthesis. The structures of the complexes were elucidated on the basis of elemental analysis, thermal decomposition, IR and mass spectroscopy. IR spectra show that N-oxides act as bidentate ligands, in which both the N-oxide and the carboxylate groups are involved in coordination. In 2 and 3 the Co(II) ion exists in the same coordination environment. For 1, the X-ray crystal structure has been determined and it turned out that it contains the coordination polymers, created by the chains of Co ions joined by 4,4'-byp ligands. The Co(II) ion occupies the center of symmetry in the space group C2/c. This ion is coordinated by two nitrogen atoms (from two 4,4'-byp ligands) and four oxygen atoms from two PNO anions. The extensive network of hydrogen bonds involving six different water molecules connects the one-dimensional polymers into three-dimensional crystal structure.

  10. Dichloridobis(3,5-dimethyl-1H-pyrazol-4-amine-κN 2)cobalt(II)

    PubMed Central

    Cai, Xing-Wei; Zhao, Yu-Yuan; Han, Guang-Fan

    2008-01-01

    In the title compound, [CoCl2(C5H9N3)2], the CoII atom adopts a slightly distorted tetra­hedral coordination geometry provided by two chloride anions and two N atoms from the organic ligands. The dihedral angle between the pyrazole rings is 85.91 (10)°. In the crystal structure, mol­ecules are linked into a three-dimensional network by inter­molecular N—H⋯N and N—H⋯Cl hydrogen-bonding inter­actions. PMID:21203006

  11. In situ tetrazole templated chair-like decanuclear azido-cobalt(II) SMM containing both tetra- and octa-hedral Co(II) ions.

    PubMed

    Zhang, Yuan-Zhu; Gao, Song; Sato, Osamu

    2015-01-14

    An azido-bridged chair-like decanuclear cluster: [Co(II)10(bzp)8(Metz)2(N3)18]·4MeOH·3H2O (1, bzp = 2-benzoylpyridine and HMetz = 5-methyl-1H-tetrazole) was prepared with in situ tetrazolate anions as templates in a sealed system. 1 containing both octahedral and tetrahedral Co(II) ions exhibited slow relaxation of magnetization with an effective barrier of 26 K under an applied dc field of 1 kOe.

  12. Crystal structure of aqua-tris-(isonicotinamide-κN)bis-(thio-cyanato-κN)cobalt(II) 2.5-hydrate.

    PubMed

    Neumann, Tristan; Jess, Inke; Näther, Christian

    2016-09-01

    The asymmetric unit of the title compound, [Co(NCS)2(C6H6N2O)3(H2O)]·2.5H2O, comprises one Co(II) cation, three isonicotinamide ligands, two thio-cyanate anions, one aqua ligand and two water solvent mol-ecules in general positions, as well as one water solvent mol-ecule that is located on a twofold rotation axis. The Co(II) cations are octa-hedrally coordinated by two terminally N-bonded thio-cyanate anions, one water mol-ecule and three isonicotinamide ligands, each coordinating via the pyridine N atom. The discrete complexes are linked by inter-molecular O-H⋯O, N-H⋯O and N-H⋯S hydrogen bonding into a three-dimensional network that contains cavities in which the solvent water mol-ecules are located. The latter are linked by further O-H⋯O hydrogen bonds to the network. There are additional short contacts present in the crystal, indicative of weak C-H⋯S, C-H⋯O and C-H⋯N inter-actions.

  13. Spectrophotometric analysis of 5-coordinate cobalt(II) species for ligand substitution of hexakis(acetonitrile)cobalt(II) with bulky 1,1,3,3-tetramethylurea in noncoordinating nitromethane.

    PubMed

    Inada, Y; Hotta, N; Kuwabara, H; Funahashi, S

    2001-01-01

    The ligand substitution reaction of [Co(an)6]2+ (an = acetonitrile) with 1,1,3,3-tetramethylurea (TMU) in the noncoordinating solvent, nitromethane, was spectrophotometrically investigated by titration. The observed spectral changes were analyzed using a model with the four steps of ligand substitution. The component complexes involved in the substitution were found to be 6-coordinate [Co(an)6]2+ and [Co(an)5(tmu)]2+, 5-coordinate [Co(an)3(tmu)2]2+ and [Co(an)2(tmu)3]2+, and 4-coordinate [Co(tmu)4]2+. The logarithmic values of the stepwise equilibrium constant are 2.17 +/- 0.26, 1.06 +/- 0.15, 1.19 +/- 0.06, and -0.4 +/- 0.4 at 25 degrees C. The decrease in the coordination number of the Co(II) ion from 6 to 5 during the formation of [Co(an)3(tmu)2]2+ and from 5 to 4 during the formation of [Co(tmu)4]2+ is ascribed to the steric repulsion between the coordinating bulky TMU molecules.

  14. Electron-transfer reactions of cobalt(III) complexes. 1. The kinetic investigation of the reduction of various surfactant cobalt(III) complexes by iron(II) in surface active ionic liquids.

    PubMed

    Nagaraj, Karuppiah; Senthil Murugan, Krishnan; Thangamuniyandi, Pilavadi; Sakthinathan, Subramanian

    2015-05-15

    The kinetics of outer sphere electron transfer reaction of surfactant cobalt(III) complex ions, cis-[Co(en)2(C12H25NH2)2](3+) (1), cis-[Co(dp)2(C12H25NH2)2](3+) (2), cis-[Co(trien)(C12H25NH2)2](3+) (3), cis-[Co(bpy)2(C12H25NH2)2](3+) (4) and cis-[Co(phen)2(C12H25NH2)2](3+) (5) (en: ethylenediamine, dp: diaminopropane, trien : triethylenetetramine, bpy: 2,2'-bipyridyl, phen: 1,10-phenanthroline and C12H25NH2 : dodecylamine) have been interrogated by Fe(2+) ion in ionic liquid (1-butyl-3-methylimidazoliumbromide) medium at different temperatures (298, 303, 308, 313, 318 and 323K) by the spectrophotometry method under pseudo first order conditions using an excess of the reductant. Experimentally the reactions were found to be of second order and the electron transfer as outer sphere. The second order rate constant for the electron transfer reaction in ionic liquids was found to increase with increase in the concentration of all these surfactant cobalt(III) complexes. Among these complexes (from en to phen ligand), complex containing the phenanthroline ligand rate is higher compared to other complexes. By assuming the outer sphere mechanism, the results have been explained based on the presence of aggregated structures containing cobalt(III) complexes at the surface of ionic liquids formed by the surfactant cobalt(III) complexes in the reaction medium. The activation parameters (enthalpy of activation ΔH(‡) and entropy of activation ΔS(‡)) of the reaction have been calculated which substantiate the kinetics of the reaction.

  15. Bio-relevant cobalt(II) complexes with compartmental polyquinoline ligand: synthesis, crystal structures and biological activities.

    PubMed

    Li, Jun-Ling; Jiang, Lin; Wang, Bi-Wei; Tian, Jin-Lei; Gu, Wen; Liu, Xin; Yan, Shi-Ping

    2015-04-01

    Three new Co(II) complexes, [Co4(L)2(μ3-CrO4)2](ClO4)2·2CH3CN (1), [Co2(L)(μ2-na)(H2O)](ClO4)2 (2) and [Co2(L)(μ2-ba)](ClO4)2·0.5CH3CN (3) (Hna=nicotinic acid, Hba=benzoic acid, HL=N,N,N',N'-tetrakis (2-quinolylmethyl)-1,3-diaminopropan-2-ol), have been synthesized and characterized by various physicochemical techniques. The Co(II) centers are connected by endogenous alkoxy bridge from L(-) and various extrinsic auxiliary linkers, some of which display coordination number asymmetry (5, 6-coordinated for 1 and 2; 5, 5-coordinated for 3). It is worth mentioning that complex 1 contains two rare reported μ3-η(1), η(1), η(1)-CrO4(2-) moieties. Susceptibility data of three complexes indicated intramolecular antiferromagnetic coupling of high-spin Co(II) atoms with exchange integral values (J) -14.94 cm(-1), -11.26 cm(-1) and -13.66 cm(-1) for 1, 2 and 3, respectively. Interaction of compounds with calf thymus DNA (CT-DNA) have been investigated by absorption spectral titration, ethidium bromide (EB) displacement assay and viscosity measurement, which revealed that compounds bound to CT-DNA with a moderate intercalative mode, accompanied the affinities order: 1>2≈3. Three complexes exhibit oxidative cleavage of pBR322 plasmid DNA including a reliance on H2O2 as the activator. Compound 1 demonstrates an increased DNA cleavage activity as compared with 2 and 3, which could degrade super coiled DNA (SC DNA) into nicked coiled DNA (NC DNA) in lower concentration (5 μM). Moreover, all compounds could quench the intrinsic fluorescence of bovine serum albumin (BSA) in a static quenching process. Complex 1 also shows higher anticancer activity than cisplatin with lower IC50 value of incubation for both 24 h and 48 h.

  16. Synthesis, characterization and antitumoral activity of new cobalt(II)complexes: Effect of the ligand isomerism on the biological activity of the complexes.

    PubMed

    Morcelli, Samila R; Bull, Érika S; Terra, Wagner S; Moreira, Rafaela O; Borges, Franz V; Kanashiro, Milton M; Bortoluzzi, Adailton J; Maciel, Leide L F; de A Almeida, João Carlos; Júnior, Adolfo Horn; Fernandes, Christiane

    2016-08-01

    The synthesis, physico-chemical characterization and cytotoxicity against five human tumoral cell lines (THP-1, U937, Molt-4, Colo205 and H460) of three new cobalt(II) coordination compounds are reported (i.e. Co(HL1)Cl (1), Co(HL2)Cl (2) and [Co(HL3)Cl]0.0.5 (CH3)2CHOH (3)). H2L2 (2-{[[2-hydroxy-3-(1-naphthyloxy)propyl](pyridin-2-ylmethyl)amino]methyl}phenol) and H2L3 (2-{[[2-hydroxy-3-(2-naphthyloxy)propyl](pyridin-2-ylmethyl)amino]methyl}phenol) present α and β-naphthyl groups respectively, which is absent in H2L1 (N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)[(3-chloro)(2-hydroxy)]propylamine. These compounds were characterized by a range of physico-chemical methods. X-ray diffraction studies were performed for complex (3), indicating the formation of a mononuclear complex. Complexes (2) and (3), which contain α and β-naphthyl groups respectively, have presented lower IC50 values than those exhibited by complex (1). Complex (3) presents IC50 values lower than cisplatin against Colo205 (90 and 196μmolL(-1), respectively) and H460 (147 and 197μmolL(-1), respectively). These human neoplastic cells under investigation were also more susceptible toward complex (3) than peripheral blood mononuclear cells. Transmission electron microscopy investigations are in agreement with the loss of mitochondrial membrane potential (ΔΨm) observed by JC-1 mitochondrial potential sensor and indicate that the activity of complex (3) against leukemic cell line (U937) is mediated by an apoptotic mechanism associated with mitochondrial dysfunction (intrinsic pathway).

  17. Effect of dispersion on surface interactions of cobalt(II) octaethylporphyrin monolayer on Au(111) and HOPG(0001) substrates: a comparative first principles study.

    PubMed

    Chilukuri, Bhaskar; Mazur, Ursula; Hipps, K W

    2014-07-21

    A density functional theory study of a cobalt(II) octaethylporphyrin (CoOEP) monolayer on Au(111) and HOPG(0001) surfaces was performed under periodic boundary conditions. Calculations with and without dispersion corrections are performed and the effect of van der Waals forces on the interface properties is analyzed. Calculations have determined that the CoOEP molecule tends to bind at the 3-fold and the 6-fold center sites on Au(111) and HOPG(0001), respectively. Geometric optimizations at the center binding sites have indicated that the porphyrin molecules (in the monolayer) lie flat on both substrates. Calculations also reveal that the CoOEP monolayer binds slightly more strongly to Au(111) than to HOPG(0001). Charge density difference plots disclose that charge is redistributed mostly around the porphyrin plane and the first layer of the substrates. Dispersion interactions cause a larger substrate to molecule charge pushback on Au(111) than on HOPG. CoOEP adsorption tends to lower the work functions of either substrate, qualitatively agreeing with the experimental photoelectron spectroscopic data. Comparison of the density of states (DOS) of the isolated CoOEP molecule with that on gold and HOPG substrates showed significant band shifts around the Fermi energy due to intermolecular orbital hybridization. Simulated STM images were plotted with the Tersoff-Hamann approach using the local density of states, which also agree with the experimental results. This study elucidates the role of dispersion for better describing porphyrin-substrate interactions. A DFT based overview of geometric, adsorption and electronic properties of a porphyrin monolayer on conductive surfaces is presented.

  18. Effect of Low Dose Lead (Pb) Administration on Tail Immersion Test and Formalin-induced Pain in Wistar Rats: Possible Modulatory Role of Cobalt (II) Chloride.

    PubMed

    Umar, A H; Suleiman, I; Muhammed, H

    2017-03-06

    Lead (Pb) is cheap and there is a long tradition of its use, but its toxic effects have also been recognized. There is increased public health concern regarding the hazards of low dose Pb exposure to adults and children. Studies have shown the risks for hypertension, decrements in renal function, subtle decline in cognitive function, and adverse reproductive outcome at low blood Pb level. In this study, the possible modulatory role of cobalt (II) chloride (CoCl2) on low level Pb exposure on tail immersion test and formalin induced pain was investigated. Twenty adult Wistar rats of both sexes (weight 150g to 200g) were used. The animals were divided into four groups (n = 5) and administered Pb (5mg/kg), Pb (5mg/kg) + CoCl2 (50mg/kg) and CoCl2 (50mg/kg) orally for twenty-eight days. The last group served as control and were given distilled water only. In the tail immersion test, there was no significant change in reaction time for all three groups when compared to the control. In the formalin-induced pain, pain score after five and forty-five minutes also do not show significant change for all the three groups when compared to control. This work suggested that exposure to 5mg/kg Pb for twenty-eight days do not significantly impair reaction time in tail immersion test and pain score in formalin induced pain in Wistar rats. Also, administration of 50mg/kg CoCl2 do not improve performance of the animals in the experiments.

  19. Light-Activated Protein Inhibition through Photoinduced Electron Transfer of a Ruthenium(II)–Cobalt(III) Bimetallic Complex

    PubMed Central

    Holbrook, Robert J.; Weinberg, David J.; Peterson, Mark D.; Weiss, Emily A.; Meade, Thomas J.

    2015-01-01

    We describe a mechanism of light activation that initiates protein inhibitory action of a biologically inert Co(III) Schiff base (Co(III)-sb) complex. Photoinduced electron transfer (PET) occurs from a Ru(II) bipyridal complex to a covalently attached Co(III) complex and is gated by conformational changes that occur in tens of nanoseconds. Reduction of the Co(III)-sb by PET initiates displacement of the inert axial imidazole ligands, promoting coordination to active site histidines of α-thrombin. Upon exposure to 455 nm light, the rate of ligand exchange with 4-methylimidazole, a histidine mimic, increases by approximately 5-fold, as observed by NMR spectroscopy. Similarly, the rate of α-thrombin inhibition increases over 5-fold upon irradiation. These results convey a strategy for light activation of inorganic therapeutic agents through PET utilizing redox-active metal centers. PMID:25671465

  20. Bis[2,4-dibromo-6-(n-propyl-imino-methyl)phenolato-κN,O]cobalt(II).

    PubMed

    Li, Chunyan; Li, Rui; Zhang, Shufang

    2010-08-18

    In the title complex, [Co(C(10)H(10)Br(2)NO)(2)], the Co(II) atom lies on a twofold rotation axis, the N(2)O(2) units having distorted tetra-hedral coordination environments comprising two bidentate chelate 2,4-dibromo-6-(n-propyl-imino-meth-yl)phenolate Schiff base ligands [Co-N = 1.989 (3) Å, Co-O = 1.924 (2) Å and O/N-Co-O/N = 94.53 (10)-125.40 (15)°]. In the crystal structure, the mol-ecules are linked via weak inter-molecular C-H⋯O hydrogen bonds [3.334 (5) Å] and there are also short inversion-related intermolecular Br⋯Br contacts [3.4263 (6) Å].

  1. Light-activated protein inhibition through photoinduced electron transfer of a ruthenium(II)–cobalt(III) bimetallic complex

    DOE PAGES

    Holbrook, Robert J.; Weinberg, David J.; Peterson, Mark D.; ...

    2015-02-11

    In this paper, we describe a mechanism of light activation that initiates protein inhibitory action of a biologically inert Co(III) Schiff base (Co(III)-sb) complex. Photoinduced electron transfer (PET) occurs from a Ru(II) bipyridal complex to a covalently attached Co(III) complex and is gated by conformational changes that occur in tens of nanoseconds. Reduction of the Co(III)-sb by PET initiates displacement of the inert axial imidazole ligands, promoting coordination to active site histidines of α-thrombin. Upon exposure to 455 nm light, the rate of ligand exchange with 4-methylimidazole, a histidine mimic, increases by approximately 5-fold, as observed by NMR spectroscopy. Similarly,more » the rate of α-thrombin inhibition increases over 5-fold upon irradiation. Finally, these results convey a strategy for light activation of inorganic therapeutic agents through PET utilizing redox-active metal centers.« less

  2. Bis[bis-(1-ethyl-benzimidazol-2-ylmeth-yl) ether]cobalt(II) dipicrate dimethyl-formamide disolvate.

    PubMed

    Wu, Huilu; Yun, Ruirui; Sun, Tao; Li, Ke; Meng, Xuan

    2009-09-12

    In the title complex, [Co(C(20)H(22)N(4)O)(2)](C(6)H(2)N(3)O(7))(2)·2C(3)H(7)NO, the Co(II) ion is coordinated by two sets of two N atoms and an O atom from two independent tridendate ligands in a distorted octa-hedral coordination environment. There are significant differences between chemically equivalent coordination bond lengths. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds and weak π-π stacking inter-actions [centroid-centroid distance 3.495 (1) Å]. In one of the anions one nitro group is rotationally disordered about the C-N bond with refined occupancies of 0.524 (8) and 0.476 (8).

  3. Light-activated protein inhibition through photoinduced electron transfer of a ruthenium(II)–cobalt(III) bimetallic complex

    SciTech Connect

    Holbrook, Robert J.; Weinberg, David J.; Peterson, Mark D.; Weiss, Emily A.; Meade, Thomas J.

    2015-02-11

    In this paper, we describe a mechanism of light activation that initiates protein inhibitory action of a biologically inert Co(III) Schiff base (Co(III)-sb) complex. Photoinduced electron transfer (PET) occurs from a Ru(II) bipyridal complex to a covalently attached Co(III) complex and is gated by conformational changes that occur in tens of nanoseconds. Reduction of the Co(III)-sb by PET initiates displacement of the inert axial imidazole ligands, promoting coordination to active site histidines of α-thrombin. Upon exposure to 455 nm light, the rate of ligand exchange with 4-methylimidazole, a histidine mimic, increases by approximately 5-fold, as observed by NMR spectroscopy. Similarly, the rate of α-thrombin inhibition increases over 5-fold upon irradiation. Finally, these results convey a strategy for light activation of inorganic therapeutic agents through PET utilizing redox-active metal centers.

  4. Uptake of indium-111-labeled platelets and indium-111 oxine by murine kidneys after total-body irradiation

    SciTech Connect

    Ebbe, S.; Taylor, S.; Maurer, H.; Kullgren, B.

    1996-08-01

    Radiation nephropathy is a well-known late manifestation of renal irradiation in human beings and experimental animals. Its pathogenesis is unclear, but vascular injury may play a role. Endothelial cells have been demonstrated to manifest a variety of abnormalities within hours of exposure to radiation. In the present experiments mice were exposed to lethal doses of whole-body radiation, and the distribution of {sup 111}In-labeled platelets was evaluated during the first week after irradiation. The purpose was to determine if early abnormalities of endothelial cells would be manifested by altered sequestration of platelets in kidneys and other organs. It was found that the indium accumulated in the kidneys of irradiated mice to a greater extent than in nonirradiated mice, but the pattern of accumulation differed from that seen after injection of radiolabeled platelets. Renal hyperemia was not demonstrable with {sup 51}Cr-labeled red cells, renal vascular permeability was not detected with {sup 125}I-labeled albumin, and the pattern of renal uptake of plasma proteins labeled albumin, and the pattern of renal uptake of plasma proteins labeled with {sup 59}Fe {sup 111}In did not coincide with that seen from {sup 111}In administered as labeled platelets or oxine. Renal uptake of {sup 111}In-oxine was not associated with alterations in urinary or fecal excretion or an increase in total-body retention of the radioisotope. The findings are consistent with the notion that renal vascular injury at the time of irradiation results in accumulation of platelets or platelet constituents during the first week after total-body irradiation of mice. 29 refs., 5 figs., 3 tabs.

  5. Sperm-macrophage interaction in the mouse: a quantitative assay in vitro using 111indium oxine-labeled sperm

    SciTech Connect

    Olive, D.L.; Weinberg, J.B.; Haney, A.F.

    1987-12-01

    The role of reproductive tract macrophages in contraception and reproductive failure has become widely recognized. However, in vitro analysis of sperm phagocytosis by macrophages has relied upon a semi-quantitative method of sperm counting that is of limited accuracy and reproducibility. We have developed an assay using murine sperm labeled with /sup 111/indium oxine, and results indicate the labeling to be rapid and efficient. Incorporation of /sup 111/indium into sperm increased the dose and sperm concentration and reached 90% maximal uptake after 15 min incubation, with maximal uptake occurring at 30 min. No decrease in sperm motility was noted with levels of oxine in excess of those required for significant labeling. Maximal labeling efficiency occurred in phosphate-buffered saline (PBS), with Dulbecco's modified Eagle's medium (DMEM) + 10% adult bovine serum (ABS) producing significantly less uptake. Label dissociation was detectable in PBS at room temperature, but at 37 degrees C in DMEM + 10% ABS, loss of label occurred at a rate of 23.5%/h. Addition of labeled sperm to murine macrophage monolayers under optimal conditions resulted in uptake of /sup 111/indium by macrophages, while free label was unincorporated. Results indicated assay specificity for macrophage-limited uptake, with insignificant label uptake by nonphagocytic murine fibroblasts and better sensitivity than sperm counting. Macrophages from Bacillus Calmette-Guerin (BCG)-infected mice resulted in a decrease in sperm uptake. Female macrophages showed greater capacity for sperm uptake than those of the male mouse. These initial studies demonstrated the utility of this model system in enhancing the understanding of sperm-macrophage interaction in the female reproductive tract.

  6. In-vitro antibacterial, antifungal and cytotoxic activity of cobalt (II), copper (II), nickel (II) and zinc (II) complexes with furanylmethyl- and thienylmethyl-dithiolenes: [1, 3-dithiole- 2-one and 1,3-dithiole-2-thione].

    PubMed

    Chohan, Zahid H; Shaikh, Ali U; Supuran, Claudiu T

    2006-12-01

    Some antibacterial and antifungal furanylmethyl-and thienylmethyl dithiolenes and, their Co(II), Cu(II), Ni (II) and Zn (II) complexes have been synthesized, characterized and screened for their in vitro antibacterial activity against four Gram-negative; Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Shigella flexeneri, and two Gram-positive; Bacillus subtilis and Staphylococcus aureus bacterial strains, and for in-vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. All compounds showed significant antibacterial and antifungal activity. The metal complexes, however, were shown to possess better activity as compared to the simple ligands. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties.

  7. Synthesis and Reactivity of Four- and Five-Coordinate Low-Spin Cobalt(II) PCP Pincer Complexes and Some Nickel(II) Analogues.

    PubMed

    Murugesan, Sathiyamoorthy; Stöger, Berthold; Carvalho, Maria Deus; Ferreira, Liliana P; Pittenauer, Ernst; Allmaier, Günter; Veiros, Luis F; Kirchner, Karl

    2014-11-10

    Anhydrous CoCl2 or [NiCl2(DME)] reacts with the ligand PCP(Me)-iPr (1) in the presence of nBuLi to afford the 15e and 16e square planar complexes [Co(PCP(Me)-iPr)Cl] (2) and [Ni(PCP(Me)-iPr)Cl] (3), respectively. Complex 2 is a paramagnetic d(7) low-spin complex, which is a useful precursor for a series of Co(I), Co(II), and Co(III) PCP complexes. Complex 2 reacts readily with CO and pyridine to afford the five-coordinate square-pyramidal 17e complexes [Co(PCP(Me)-iPr)(CO)Cl] (4) and [Co(PCP(Me)-iPr)(py)Cl] (5), respectively, while in the presence of Ag(+) and CO the cationic complex [Co(PCP(Me)-iPr)(CO)2](+) (6) is afforded. The effective magnetic moments μeff of all Co(II) complexes were derived from the temperature dependence of the inverse molar magnetic susceptibility by SQUID measurements and are in the range 1.9 to 2.4 μB. This is consistent with a d(7) low-spin configuration with some degree of spin-orbit coupling. Oxidation of 2 with CuCl2 affords the paramagnetic Co(III) PCP complex [Co(PCP(Me)-iPr)Cl2] (7), while the synthesis of the diamagnetic Co(I) complex [Co(PCP(Me)-iPr)(CO)2] (8) was achieved by stirring 2 in toluene with KC8 in the presence of CO. Finally, the cationic 16e Ni(II) PCP complex [Ni(PCP(Me)-iPr)(CO)](+) (10) was obtained by reacting complex 3 with 1 equiv of AgSbF6 in the presence of CO. The reactivity of CO addition to Co(I), Co(II), and Ni(II) PCP square planar complexes of the type [M(PCP(Me)-iPr)(CO)] (n) (n = +1, 0) was investigated by DFT calculations, showing that formation of the Co species, 6 and 8, is thermodynamically favorable, while Ni(II) maintains the 16e configuration since CO addition is unfavorable in this case. X-ray structures of most complexes are provided and discussed. A structural feature of interest is that the apical CO ligand in 4 deviates significantly from linearity, with a Co-C-O angle of 170.0(1)°. The DFT-calculated value is 172°, clearly showing that this is not a packing but an electronic effect.

  8. Diacridinium trans-diaqua­bis(pyrazine-2,3-dicarboxyl­ato)cobaltate(II) hexa­hydrate

    PubMed Central

    Aghabozorg, Hossein; Attar Gharamaleki, Jafar; Parvizi, Mahdieh; Derikvand, Zohreh

    2010-01-01

    The title compound, (C13H10N)2[Co(C6H2N2O4)2(H2O)2]·6H2O, consists of mononuclear trans-[Co(pz-2,3-dc)2(H2O)2]2− complex anions, (acrH)+ cations and uncoordinated water mol­ecules (acr is acridine and pz-2,3-dcH2 is pyrazine-2,3-dicarboxylic acid). The CoII atom, which lies on a crystallographic center of symmetry, has a slightly distorted octa­hedral coordination environment, with two N and two O atoms from the (pz-2,3-dc)2− ligands in the equatorial plane and with two water mol­ecules in axial positions. In the crystal, the components are held together by two distinct N—H⋯O and C—H⋯O hydrogen bonds with R 2 2(8) graph-sets. The coordinated and uncoordinated water mol­ecules are also involved in O—H⋯O hydrogen bonds, which lead to the formation of layers with R 3 3(12) graph-set motifs. Extensive π–π stacking inter­actions between parallel aromatic rings of the acridinium ions, with distances ranging from 3.533 (1) to 3.613 (1) Å, occur in the structure. PMID:21579976

  9. Biogenic glutamic acid-based resin: Its synthesis and application in the removal of cobalt(II).

    PubMed

    Jamiu, Zakariyah A; Saleh, Tawfik A; Ali, Shaikh A

    2017-04-05

    Inexpensive biogenic glutamic acid has been utilized to synthesize a cross-linked dianionic polyelectrolyte (CDAP) containing metal chelating ligands. Cycloterpolymerization, using azoisobutyronitrile as an initiator, of N,N-diallylglutamic acid hydrochloride, sulfur dioxide and a cross-linker afforded a pH-responsive cross-linked polyzwitterionic acid (CPZA) which upon basification with NaOH was converted into CDAP. The new resin, characterized by a multitude of spectroscopic techniques as well as Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) analyses, was evaluated for the removal of Co(II) as a model case under different conditions. The adsorption capacity of 137mgg(-1) does indeed make the resin as one of the most effective sorbents in recent times. The resin leverages its cheap natural source and ease of regeneration in combination with its high and fast uptake capacities to offer a great promise for wastewater treatment. The resin has demonstrated remarkable efficiency in removing toxic metal ions including arsenic from a wastewater sample.

  10. Synthesis, X-ray crystal structure and spectroscopy of a Werner-type host Co(II) complex, trans-bisisothiocyanatotetrakis( trans-4-styrylpyridine)cobalt(II)

    NASA Astrophysics Data System (ADS)

    Karunakaran, C.; Thomas, K. R. J.; Shunmugasundaram, A.; Murugesan, R.

    2000-05-01

    Single crystals of the title Co(II) complex, [Co(stpy) 4(NCS) 2] [stpy= trans-4-styrylpyridine] are prepared and characterized by elemental analysis, IR, and UV-visible spectroscopy and X-ray crystal structure determination. The complex crystallizes in the orthorhombic space group Pna2 1 with unit-cell parameters, a=32.058(3), b=15.362(5), c=9.818(5) Å, and Z=4. The structure consists of discrete monomeric units of [Co(stpy) 4(NCS) 2]. The equatorial positions of the Co(II) polyhedron are occupied by nitrogen atoms of the four stpy ligands and the axial positions are occupied by the nitrogen atoms of the two thiocyanate ions. The unit cell packing reveals interpenetration of styryl groups owing to conformational flexibility of phenyl and pyridyl rings in stpy ligands. Thus, it leads to efficient packing of the crystal lattice leaving no space available for guest inclusion. IR spectra reveal nitrogen coordination from stpy and terminal -NCS coordination of the thiocyanate group. The optical reflectance bands 475, 540 (shoulder) and 1022 nm suggest octahedral geometry in accordance with the X-ray data. However, the optical spectrum of acetonitrile solution shows an intense band at 615 nm and a weak shoulder at 570 nm suggesting participation of the solvent molecules in the coordination sphere. These bands indicate the presence of both tetrahedral and octahedral species in solution.

  11. Immobilization of cobalt(II) Schiff base complexes on polystyrene resin and a study of their catalytic activity for the aerobic oxidation of alcohols.

    PubMed

    Jain, Suman; Reiser, Oliver

    2008-01-01

    The copper-catalyzed [3+2] azide-alkyne cycloaddition and the Staudinger ligation are readily applicable and highly efficient for the immobilization of cobalt Schiff base complexes onto polystyrene resins. Stepwise synthesis of polymer-bound Schiff bases followed by their subsequent complexation with metal ions were successfully carried out. Direct covalent attachment of preformed homogeneous cobalt Schiff base complexes to the resins was also possible. The catalytic efficiency of the so-prepared polystyrene-bound cobalt Schiff bases was studied for the oxidation of alcohols to carbonyl compounds using molecular oxygen as oxidant. The immobilized complexes were highly efficient and even more reactive than the corresponding homogenous analogues, thus affording better yields of oxidized products within shorter reaction times. The supported catalysts could easily be recovered from the reaction mixture by simple filtration and reused for subsequent experiments with consistent catalytic activity.

  12. Cadmium(II) and cobalt(II) complexes generated from benzimidazole-5-carboxylate: Self-assembly by hydrogen bonding and {pi}-{pi} interactions

    SciTech Connect

    Liu Zheng; Chen Yun; Liu Ping . E-mail: pliu@ms.fjirsm.ac.cn; Wang Jian; Huang Meihua

    2005-07-15

    Self-assembly of L{sup -} (HL=benzimidazole-5-carboxylic acid) with Cd(II) and Co(II), respectively, by layer-separating diffusion method at ambient temperature gives rise to two new supramolecular architectures [(CdL{sub 2}.H{sub 2}O).2CH{sub 3}OH]{sub n} (1) and {l_brace}[CoL{sub 2}(H{sub 2}O){sub 2}].2H{sub 2}O{r_brace}{sub n} (2), both of which are stabilized by the hydrogen bonding interactions and the intermolecular {pi}-{pi} interactions. 1 crystallizes in the triclinic system, space group P-1, with cell parameters M=516.78, a=9.084(2)A, b=10.063(10)A, c=11.533(8)A, {alpha}=90.21(11){sup o}, {beta}=99.48(6){sup o}, {gamma}=98.34(9){sup o}, V=1028.4(12)A{sup 3}, Z=2, R{sub 1}[I>2{sigma}(I)]=0.0257, wR{sub 2}[I>2{sigma}(I)]=0.0719. 2 crystallizes in the monoclinic system, space group C2/c, with cell parameters M=453.27, a=16.119(2)A, b=8.8952(13)A, c=14.195(2)A, {beta}=118.507(2){sup o}, V=1788.5(4)A{sup 3}, Z=4, R{sub 1}[I>2{sigma}(I)]=0.0802, wR{sub 2}[I>2{sigma}(I)]=0.1515. Complex 1 displays a remarkable three-dimensional (3-D) structure with unusual channels generated from the interlayer voids. Complex 2 exhibits the 3-D structure consisting of 1-D zigzag chains. The thermal and fluorescence properties associated with their crystal structures have been measured, and complex 1 displays intense blue emission in the solid state.

  13. Cobalt free maraging steel

    SciTech Connect

    Floreen, S.

    1984-04-17

    The subject invention is directed to ferrous-base alloys, particularly to a cobalt-free maraging steel of novel chemistry characterized by a desired combination of strength and toughness, notwithstanding that cobalt is non-essential.

  14. Splitting water with cobalt.

    PubMed

    Artero, Vincent; Chavarot-Kerlidou, Murielle; Fontecave, Marc

    2011-08-01

    The future of energy supply depends on innovative breakthroughs regarding the design of cheap, sustainable, and efficient systems for the conversion and storage of renewable energy sources, such as solar energy. The production of hydrogen, a fuel with remarkable properties, through sunlight-driven water splitting appears to be a promising and appealing solution. While the active sites of enzymes involved in the overall water-splitting process in natural systems, namely hydrogenases and photosystem II, use iron, nickel, and manganese ions, cobalt has emerged in the past five years as the most versatile non-noble metal for the development of synthetic H(2)- and O(2)-evolving catalysts. Such catalysts can be further coupled with photosensitizers to generate photocatalytic systems for light-induced hydrogen evolution from water.

  15. Copper catalysis for enhancement of cobalt leaching and acid utilization efficiency in microbial fuel cells.

    PubMed

    Liu, Yaxuan; Shen, Jingya; Huang, Liping; Wu, Dan

    2013-11-15

    Enhancement of both cobalt leaching from LiCoO2 and acid utilization efficiency (AUE) in microbial fuel cells (MFCs) was successfully achieved by the addition of Cu(II). A dosage of 10mg/L Cu(II) improved both cobalt leaching up to 308% and AUE of 171% compared to the controls with no presence of Cu(II). The apparent activation energy of cobalt leaching catalyzed by Cu(II) in MFCs was only 11.8 kJ/mol. These results demonstrate cobalt leaching in MFCs using Cu(II) as a catalyst may be an effective strategy for cobalt recovery and recycle of spent Li-ion batteries, and the evidence of influence factors including solid/liquid ratio, temperature, and pH and solution conductivity can contribute to improving understanding of and optimizing cobalt leaching catalyzed by Cu(II) in MFCs.

  16. Thrombus detection with a radiolabeled antiplatelet monoclonal antibody: Comparison with In-111-oxine technique in coronary and peripheral thrombi in dogs

    SciTech Connect

    Srivastava, S.C.; Esekowitz, M.D.; Meinken, G.E.; Lange, R.C.; Smith, E.; Carbo, P.; Scudder, L.E.; Coller, B.

    1985-05-01

    Platelets (P) labeled with low concentrations of an I-123 or In-111 labeled anti-P monoclonal antibody (7E3) were shown earlier to successfully image in-vivo thrombi. This study was carried out to compare this technique with In-111-oxine-P for localizing coronary and venous thrombi (CT and DVT) in dogs. Thrombi were induced using either transcatheter placement of a dacron pug, mechanical trauma, or electrocoagulation. 7E3 was labeled with I-131 in 70 +- 10% yield (labeling conditions: 100 ..mu..g 7E3; 5 ..mu..g chloramine T; I/sup -//7E3 less than or equal to1; 2 min reaction; 200 ..mu..l pH 7 phosphate buffer; Sp. act. 10-30 ..mu..Ci/..mu..g). Binding of I-131-7E3 to dog P was 75 +- 10% after 1 hr incubation with whole blood. The dogs were injected with 0.5 mCi In-111-oxine-P and 1 mCi I-131-7E3-P in quick succession and data (blood clearance and imaging) were collected for 4 hr. In one experiment, DVT were clearly imaged within 10 min and CT in 30-60 min with I-131-7E3-P. In contrast, In-oxine-P required at least 30 min for imaging DVT and CT were only faintly visualized at 3-4 hr. The DVT to blood and CT to blood ratios at 2.4 hr were 16 and 12.3 for I-131-7E3-P and 9.4 and 6.5 for In-111-oxine-P respectively. In these preliminary studies, I-131-7E3-P thus appears to be superior to In-oxine-P for imaging venous and coronary thrombi. Additionally, 7E3 can be labeled with Tc-99m and I-123 for reduced dose and better imaging properties.

  17. Comparison of different surface modification techniques for electrodes by means of electrochemistry and micro synchrotron radiation X-ray fluorescence. dimerization of cobalt(II) tetrasulfonated phthalocyanine and its influence on the electrodeposition on gold surfaces.

    PubMed

    Peeters, Karl; De Wael, Karolien; Vincze, Laszlo; Adriaens, Annemie

    2005-09-01

    This paper compares different electrochemical surface modification techniques with special attention to the immobilization of cobalt(II) tetrasulfonated phthalocyanine tetrasodium salt (Co(II)TSPc) on gold electrodes. Electrochemical and synchrotron radiation X-ray fluorescence (SR-XRF) microbeam analysis were performed in order to compare the amount of adsorbed CoTSPc onto the gold electrode and to determine the level of uniformity of the deposited layer. The nondestructive, quantitative characterization of CoTSPc deposition on gold electrodes by means of scanning SR-XRF on the microscopic scale has never been described before. The described methodology can be in general used for thin-film characterization. Depending on the degree of dimerization of the CoTSPc molecules, different electrochemical behavior is observed.

  18. Update on the genotoxicity and carcinogenicity of cobalt compounds

    PubMed Central

    Lison, D; De Boeck, M; Verougstraete, V; Kirsch-Volders, M

    2001-01-01

    OBJECTIVE—To integrate recent understandings of the mechanisms of genotoxicity and carcinogenicity of the different cobalt compounds.
METHOD—A narrative review of the studies published since the last IARC assessment in 1991 (genotoxicity, experimental carcinogenesis, and epidemiology).
RESULTS—Two different mechanisms of genotoxicity, DNA breakage induced by cobalt metal and especially hard metal particles, and inhibition of DNA repair by cobalt (II) ions contribute to the carcinogenic potential of cobalt compounds. There is evidence that soluble cobalt (II) cations exert a genotoxic and carcinogenic activity in vitro and in vivo in experimental systems but evidence in humans is lacking. Experimental data indicate some evidence of a genotoxic potential for cobalt metal in vitro in human lymphocytes but there is no evidence available of a carcinogenic potential. There is evidence that hard metal particles exert a genotoxic and carcinogenic activity in vitro and in human studies, respectively. There is insufficient information for cobalt oxides and other compounds.
CONCLUSION—Although many areas of uncertainty remain, an assessment of the carcinogenicity of cobalt and its compounds requires a clear distinction between the different compounds of the element and needs to take into account the different mechanisms involved.


Keywords: cobalt; DNA breakage; inhibition of DNA repair PMID:11555681

  19. A quantitative method to measure human platelet chemotaxis using /sup 111/In-oxine-labeled gel-filtered platelets

    SciTech Connect

    Lowenhaupt, R.W.; Silberstein, E.B.; Sperling, M.I.; Mayfield, G.

    1982-12-01

    Human blood platelets have been shown to migrate directionally and specifically toward collagen in plasma in vitro. We have developed a new system to monitor this behavior using a linear 7-compartment chamber with /sup 111/In-oxine-labeled gel-filtered platelets. The compartments are separated by various Nuclepore and Millipore filter membranes. Radiolabeled platelets suspended in plasma are placed in the central compartment and the other compartments are filled with platelet-free plasma. When collagen is added to an end compartment, platelets migrate toward that end. The degree of this directed movement or chemotaxis can be measured by counting the radioactivity of the contents of each compartment and then comparing the counts from radiolabeled platelets that have moved to the end that holds the chemotactic inducer with those that have randomly migrated to the opposite end, containing only plasma. This assay system allows quantitative comparisons between the chemotaxis-inducing abilities of different substances and permits the study of soluble materials. Experiments to determine the optimal conditions for the procedure are reported, and the advantages of this new method for the investigation of platelet chemotaxis and the identification of chemotaxins are discussed.

  20. A quantitative method to measure human platelet chemotaxis using indium-111-oxine-labeled gel-filtered platelets

    SciTech Connect

    Lowenhaupt, R.W.; Silberstein, E.B.; Sperling, M.I.; Mayfield, G.

    1982-12-01

    Human blood platelets have been shown to migrate directionally and specifically toward collagen in plasma in vitro. We have developed a new system to monitor this behavior using a linear 7-compartment chamber with /sup 111/In-oxine-labeled gel-filtered platelets. The compartments are separated by various Nuclepore and Millipore filter membranes. Radiolabeled platelets suspended in plasma are placed in the central compartment and the other compartments are filled with platelet-free plasma. When collagen is added to an end compartment, platelets migrate toward that end. The degree of this directed movement or chemotaxis can be measured by counting the radioactivity of the contents of each compartment and then comparing the counts from radiolabeled platelets that have moved to the end that holds the chemotactic inducer with those that have randomly migrated to the opposite end, containing only plasma. This assay system allows quantitative comparisons between the chemotaxis-inducing abilities of different substances and permits the study of soluble materials. Experiments to determine the optimal conditons for the procedure are reported, and the advantages of this new method for the investigation of platelet chemotaxis and the identification of chemotaxins are discussed.

  1. Scintigraphic assessment of bowel involvement and disease activity in Crohn's disease using technetium 99m-hexamethyl propylene amine oxine as leukocyte label

    SciTech Connect

    Schoelmerich, J.S.; Schmidt, E.; Schuemichen, C.B.; Billmann, P.; Schmidt, H.; Gerok, W.

    1988-11-01

    Using a novel labeling technique with technetium 99m-hexamethyl propylene amine oxine, we studied 29 patients with known or suspected Crohn's disease. Technetium 99m-hexamethyl propylene amine oxine leukocyte scanning (99mTc scan) was prospectively compared with the results of independently performed radiologic, endoscopic, and histologic examinations, and with findings at surgery, to assess the clinical usefulness of this technique to localize inflammatory lesions. In addition, uptake of technetium 99m-hexamethyl propylene amine oxine in the bowel was graded by comparing it with the uptake in liver and bone marrow and correlating this with established parameters of disease activity. The viability of homologous labeled leukocytes was greater than 95%. Less than 5% of lymphocytes were found in the final preparation. It was found that 45% +/- 12% of the label was bound to granulocytes, and 98% of the unbound label was washed off before reinjection. The results of 99mTc scan revealed a good correlation with those of barium enema (r = 0.880, p less than 0.001), of endoscopy/surgery (r = 0.983, p less than 0.001), and of all combined reference methods (r = 0.981, p less than 0.001). Activity as determined by 99mTc scan was weakly correlated with the results of Crohn's disease activity index (r = 0.559, p less than 0.01), van Hees index (r = 0.606, p less than 0.01), and erythrocyte sedimentation rate (r = 0.456, p less than 0.05) in 24 patients with proven Crohn's disease. The correlation was improved when the 99mTc scan was compared with a combination of these activity parameters and C-reactive protein (r = 0.781, p less than 0.001). Extraintestinal manifestations (joints) and complications (cholecystitis) were also identified correctly by the 99mTc scan.

  2. Binuclear copper(II), cobalt(II) and nickel(II) complexes of N1-ethyl-N2-(pyridin-2-yl) hydrazine-1,2-bis(carbothioamide): structural, spectral, pH-metric and biological studies.

    PubMed

    El-Gammal, O A; Abu El-Reash, G M; El-Gamil, M M

    2012-10-01

    Binuclear Cu(II), Co(II) and Ni(II) complexes derived from N(1)-ethyl-N(2)-(pyridin-2-yl) hydrazine-1,2-bis(carbothioamide) (H(2)PET) have been prepared and characterized by elemental analysis, spectral (IR, UV-vis, EI mass, ESR and (1)HNMR) and magnetic measurements. The isolated complexes assigned the general formula, [M(HPET)(H(2)O)(n)Cl](2)·xH(2)O where M=Cu(II), Co(II) and Ni(II), n=2, 1, 0 and x=0, 0.5 and 0, respectively. IR data revealed that the ligand behaves as monobasic tridentate through (CN)(py), (C-S) and new azomethine, (NC)(∗) groups in the Co(II) complex but in Cu(II) complex, the ligand coordinate via both (CS) groups, one of them in thiol form as well as the new azomethine group. In Ni(II) complex, H(2)PET acts as NSNS monobasic tetradente via (CN)(py), (C-S), (CS) and the new azomethine, (NC)(∗) groups. An octahedral geometry is proposed for all complexes. pH- metric titration was carried out in 50% dioxane-water mixture at 298, 308 and 318 °K, respectively and the dissociation constant of the ligand as well as the stability constants of its complexes were evaluated. Also the kinetic and thermodynamic parameters for the different thermal decomposition steps of the complexes were determined by Coats-Redfern and Horowitz-Metzger methods. Moreover, the anti-oxidant, anti-hemolytic, and cytotoxic activities of the compounds have been tested.

  3. Deprotonation or protonation: The coordination properties, crystal structures and spectra of cobalt (II) complex with 1-(2-pyridylazo)-2-acenaphthequinol ligand

    NASA Astrophysics Data System (ADS)

    Zhou, Jian-Liang; Sun, Hong-Wen; Yin, Dong-Hong; Li, Yan-Ling; Tuo, Su-Xing; Xu, Ya-Hui; Yan, Jun

    2017-04-01

    The reaction of 1-(2-pyridylazo)-2-acenaphthequinol (PAAL) with cobalt acetate in CHCl3 gave the complex of Co(PAAL-H)2 (1), and (PAAL + H)2[CoCl4]·2H2O (2) was isolated in the same system with ultraviolet light irradiation. Structures of both compounds were determined by X-Ray diffraction. The PAAL ligand was deprotonated in 1, but it further protonated on N position at pyridine group in 2 and form cations. The spectra of these two compounds were also studied, as well as the fluorescence properties. Also, the redox property of 1 was preliminary investigated by cyclic voltammogram.

  4. Cobalt(II)-mediated synthesis of 2,6-bis[5,7-di-tert-butyl-1,3-benzoxazol-2-yl]-pyridine: Structural analysis and coordination behavior

    NASA Astrophysics Data System (ADS)

    Garza-Ortíz, Ariadna; Martínez, Pablo A.; Duarte-Hernández, Angelica M.; Mijangos, Edgar; Flores-Álamo, Marcos; Pérez-Casas, Carol; Camacho-Camacho, Carlos; Contreras, Rosalinda; Flores-Parra, Angelina; Reedijk, Jan; Barba-Behrens, Norah

    2013-01-01

    The oxidative cyclization of 2,6-bis[2,4-di-tert-butyl-6-(methylidenylamino)phenol]-pyridine (L1) in acetonitrile, through the cobalt(II) coordination compound of L1, has resulted in a convenient route for the preparation of 2,6-bis[5,7-di-tert-butyl-1,3-benzoxazol-2-yl]-pyridine (L3). The X-ray diffraction analysis of L3 shows a planar molecule, with the oxygen atoms from the benzoxazole rings oriented to the pyridine nitrogen atom (conformer L3a). Ab initio calculations indicate that from the three possible planar conformers of L3, the more stable is L3a. The solid state conformation of the free ligand L3 and the relative energy of the three calculated conformers indicated stabilizing N → O interactions. Calculations of the protonated derivative of L3, compound 7, indicated that the most stable conformer has the benzoxazole nitrogen atoms pointing to the protonated pyridine NH (7c). The X-ray crystal analysis of ligand L3 coordinated to cobalt(II) nitrate, compound 4 is presented and conformer L3c is found in this compound. Two acid:base complexes [Zn(NO3)2(H2O)2][L3c]2, compound 5, and [NEt2H2Cl][L3c], compound 6, have also been investigated. Complex 5 crystallized and its X-ray diffraction analysis is reported, whereas compound 6 was studied in solution by NMR, mass spectrometry and ab initio calculations. Both complexes show that conformer L3c can form stable hydrogen bonding associations, with molecules having the motif YH2 (Y = N or O), that are of interest for building up supramolecular associations.

  5. Synthesis and characterization of dinuclear macrocyclic cobalt(II), copper(II) and zinc(II) complexes derived from 2,2,2('),2(')-S,S[bis(bis-N,N-2-thiobenzimidazolyloxalato-1,2-ethane)]: DNA binding and cleavage studies.

    PubMed

    Arjmand, Farukh; Aziz, Mubashira

    2009-02-01

    New homodinuclear macrocyclic complexes of cobalt(II), copper(II) and zinc(II) were isolated from the newly synthesized ligand 2,2,2',2'-S,S[bis(bis-N,N-2-thiobenzimidazolyloxalato-1,2-ethane)]. The structures of the complexes were elucidated by elemental analysis, molar conductance measurements, IR, 1H NMR, 13C NMR, electronic and ESI-MS spectroscopic techniques. In complex 1, Co(II) ions possess a tetrahedral coordination environment composed of O2S2 donor atoms while its Cu(II) and Zn(II) counterparts 2 and 3, respectively, reveal a six coordinate octahedral structure, defined by the O2S2 donors from the macrocyclic ring and two chloride ions. Molar conductance and spectroscopic data also support the proposed geometry of the complexes. DNA binding properties of complexes 1-3 were investigated using electronic absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and cyclic voltammetry. The absorption spectra of complexes 2 and 3 with calf thymus DNA showed hypochromism, while complex 1 showed hyperchromism attributed to a partial intercalation and electrostatic binding modes, respectively. The intrinsic binding constant K(b) of complexes 1-3 were determined as 16.6 x 10(4) M(-1), 4.25 x 10(4) M(-1) and 3.0 x 10(4) M(-1), respectively. The decrease in the relative specific viscosity of calf thymus DNA with increasing concentration of the complexes authenticates the partial intercalation binding mode. Gel electrophoresis of complex 2 with plasmid DNA demonstrated that complex exhibits excellent "artificial" nuclease activity.

  6. Solvent extraction of cobalt from laterite-ammoniacal leach liquors

    SciTech Connect

    Nilsen, D.N.; Siemens, R.E.; Rhoads, S.C.

    1980-01-01

    The Bureau of Mines is developing a method to recover Ni, Co, and Cu from laterites containing less than 1.2% Ni and 0.25% Co. The method consists of the following basic unit operations: (1) reduction roasting, (2) leaching, (3) solvent extraction, and (4) electrowinning. The method reflects three Bureau of Mines objectives: (1) recovery of critical minerals that are domestically in short supply from low-grade domestic laterites, (2) lower processing energy requirements, and (3) solution recycling. This report deals with the extraction of cobalt and the preparation of a suitable cobalt electrolyte by solvent extraction from liquor produced by this method. Nickel and copper are coextracted with LIX64N from an ammoniacal ammonium sulfate leach liquor containing about 1.00 g/1 Ni, 0.30 g/1 Co, 0.03 g/1 Cu, and 0.02 g/1 Zn. Cobalt (III) in the nickel-copper barren raffinate is reduced to cobalt (II) with cobalt metal. Reduction of cobalt (III) to cobalt (II) greatly aids subsequent extraction. Commercially available XI-51 extracts about 94% of the cobalt from the treated raffinate in one stage in a laboratory mixer-settler continuous circuit. Ammonia loaded on the solvent is removed in two washing steps. About 94% of the cobalt then is stripped from the XI-51 in one stage with spent cobalt electrolyte containing about 77 g/1 Co and 18 g/1 sulfuric acid (H/sub 2/SO/sub 4/). Electrolytes containing less H/sub 2/SO/sub 4/ also may be used. Preliminary data indicate that coextracted zinc may be removed from pregnant cobalt electrolyte containing 3 g/1 or less H/sub 2/SO/sub 4/ with di-(2 ethylhexyl) phosphoric acid (D2EHPA).

  7. Crystallographic studies of metal ion-DNA interactions: different binding modes of cobalt(II), copper(II) and barium(II) to N7 of guanines in Z-DNA and a drug-DNA complex.

    PubMed Central

    Gao, Y G; Sriram, M; Wang, A H

    1993-01-01

    Metal ion coordination to nucleic acids is not only required for charge neutralization, it is also essential for the biological function of nucleic acids. The structural impact of different metal ion coordinations of DNA helices is an open question. We carried out X-ray diffraction analyses of the interactions of the two transition metal ions Co(II) and Cu(II) and an alkaline earth metal ion Ba(II), with DNA of different conformations. In crystals, Co(II) ion binds exclusively at the N7 position of guanine bases by direct coordination. The coordination geometry around Co(II) is octahedral, although some sites have an incomplete hydration shell. The averaged Co-N7 bond distance is 2.3 A. The averaged Co-N7-C8 angle is 121 degrees, significantly smaller than the value of 128 degrees if the Co-N7 vector were to bisect the C5-N7-C8 bond angle. Model building of Co(II) binding to guanine N7 in B-DNA indicates that the coordinated waters in the axial positions would have a van der Waals clash with the neighboring base on the 5' side. In contrast, the major groove of A-DNA does not have enough room to accommodate the entire hydration shell. This suggests that Co(II) binding to either B-DNA or A-DNA may induce significant conformational changes. The Z-DNA structure of Cu(II)-soaked CGCGTG crystal revealed that the Cu(II) ion is bis-coordinated to N7 position of G10 and #G12 (# denotes a symmetry-related position) bases with a trigonal bipyramid geometry, suggesting a possible N7-Cu-N7 crosslinking mechanism. A similar bis-coordination to two guanines has also been seen in the interaction of Cu(II) in m5CGUAm5CG Z-DNA crystal and of Ba(II) with two other Z-DNA crystals. PMID:8371984

  8. A redox-silent analogue of tocotrienol inhibits cobalt(II) chloride-induced VEGF expression via Yes signaling in mesothelioma cells.

    PubMed

    Sato, Ayami; Virgona, Nantiga; Ando, Akira; Ota, Masako; Yano, Tomohiro

    2014-01-01

    Vascular endothelial growth factor (VEGF) plays a crucial role in tumor angiogenesis and represents an attractive anticancer target. We have previously demonstrated that a redox-silent analogue of α-tocotrienol, 6-O-carboxypropyl-α-tocotrienol (T3E) exhibits potent anti-carcinogenic property in human malignant mesothelioma (MM) cells. However, inhibition of tumor growth by targeting VEGF pathway remains undetermined. In this study, we explored the inhibitory effect of T3E on the paracrine secretion of VEGF in MM cells under mimicked hypoxia by cobalt chloride (CoCl2). In this study we examine whether T3E can suppress the secretion of VEGF in MM cells exposed to mimic hypoxia by cobalt chloride (CoCl2). We found that CoCl2-induced hypoxia treatment leads to increased up-regulated hypoxia-inducible factor-2α (HIF-2α) and subsequently induced the secretion of VEGF in MM cells. This up-regulation activation mainly depended on the activation of Yes, a member of the Src family of kinases. Treatment of hypoxic MM cells with T3E effectively inhibited the secretion of VEGF, On the other hand, T3E inhibited CoCl2-induced gene expression of VEGF due to the inactivation of Yes/HIF-2α signaling. These data suggest that Yes/HIF2-α/VEGF could be a promising therapeutic target of T3E in MM cells.

  9. International strategic minerals inventory summary report; cobalt

    USGS Publications Warehouse

    Crockett, R.N.; Chapman, G.R.; Forrest, M.D.

    1987-01-01

    Major world resources of cobalt are described in this summary report of information in the International Strategic Minerals Inventory {ISMI}. ISMI is a cooperative data-collection effort of earth-science and mineral-resource agencies in Australia, Canada, the Federal Republic of Germany, the Republic of South Africa, and the United States of America. This report, designed to be of benefit to policy analysts, contains two parts. Part I presents an overview of the resources and potential supply of cobalt on the basis of inventory information. Part II contains tables of some of the geologic information and mineral-resource and production data that were collected by ISMI participants.

  10. Cobalt(II), Nickel(II) and Copper(II) complexes of a tetradentate Schiff base as photosensitizers: Quantum yield of 1O2 generation and its promising role in anti-tumor activity.

    PubMed

    Pradeepa, S M; Bhojya Naik, H S; Vinay Kumar, B; Indira Priyadarsini, K; Barik, Atanu; Ravikumar Naik, T R

    2013-01-15

    In the present investigation, a Schiff base N'1,N'3-bis[(E)-(5-bromo-2-hydroxyphenyl)methylidene]benzene-1,3-dicarbohydrazide and its metal complexes have been synthesized and characterized. The DNA-binding studies were performed using absorption spectroscopy, emission spectra, viscosity measurements and thermal denatuaration studies. The experimental evidence indicated that, the Co(II), Ni(II) and Cu(II) complexes interact with calf thymus DNA through intercalation with an intrinsic binding constant Kb of 2.6×10(4) M(-1), 5.7×10(4) M(-1) and 4.5×10(4) M(-1), respectively and they exhibited potent photodamage abilities on pUC19 DNA, through singlet oxygen generation with quantum yields of 0.32, 0.27 and 0.30 respectively. The cytotoxic activity of the complexes resulted that they act as a potent photosensitizers for photochemical reactions.

  11. Cobalt(II), Nickel(II) and Copper(II) complexes of a tetradentate Schiff base as photosensitizers: Quantum yield of 1O2 generation and its promising role in anti-tumor activity

    NASA Astrophysics Data System (ADS)

    Pradeepa, S. M.; Bhojya Naik, H. S.; Vinay Kumar, B.; Indira Priyadarsini, K.; Barik, Atanu; Ravikumar Naik, T. R.

    2013-01-01

    In the present investigation, a Schiff base N'1,N'3-bis[(E)-(5-bromo-2-hydroxyphenyl)methylidene]benzene-1,3-dicarbohydrazide and its metal complexes have been synthesized and characterized. The DNA-binding studies were performed using absorption spectroscopy, emission spectra, viscosity measurements and thermal denatuaration studies. The experimental evidence indicated that, the Co(II), Ni(II) and Cu(II) complexes interact with calf thymus DNA through intercalation with an intrinsic binding constant Kb of 2.6 × 104 M-1, 5.7 × 104 M-1 and 4.5 × 104 M-1, respectively and they exhibited potent photodamage abilities on pUC19 DNA, through singlet oxygen generation with quantum yields of 0.32, 0.27 and 0.30 respectively. The cytotoxic activity of the complexes resulted that they act as a potent photosensitizers for photochemical reactions.

  12. Synthesis and electrochemistry of β-pyrrole nitro-substituted cobalt(II) porphyrins. The effect of the NO₂ group on redox potentials, the electron transfer mechanism and catalytic reduction of molecular oxygen in acidic media.

    PubMed

    Sun, Bin; Ou, Zhongping; Yang, Shuibo; Meng, Deying; Lu, Guifen; Fang, Yuanyuan; Kadish, Karl M

    2014-07-28

    Four cobalt(II) porphyrins, two of which contain a β-pyrrole nitro substituent, were synthesized and characterized by electrochemistry and spectroelectrochemistry. The investigated compounds are represented as (TRPP)Co and (NO2TRPP)Co, where TRPP is the dianion of a substituted tetraphenylporphyrin and R is a CH3 or OCH3 substituent on the four phenyl rings of the macrocycle. Two reductions and three oxidations are observed for each compound in CH2Cl2 containing 0.10 M tetra-n-butylammonium perchlorate. The first reduction of the compounds without a nitro substituent is metal-centered and leads to formation of a Co(I) porphyrin which then reacts with the CH2Cl2 solvent to generate a carbon σ-bonded Co(III)-R complex. A further reduction then occurs at more negative potentials to generate an unstable Co(II) σ-bonded compound. In contrast to these reactions, the first reduction of the nitro-substituted porphyrins is macrocycle-centered under the same solution conditions and gives a Co(II) porphyrin π-anion radical product. This reversible electron transfer is then followed at more negative potentials by a second reversible one-electron addition to give a Co(II) dianion. Three reversible one-electron oxidations are also seen for each compound. The first is metal-centered and the next two involve the conjugated π-system of the macrocycle. Each neutral Co(II) porphyrin was also examined as to its catalytic activity for electroreduction of molecular oxygen when coated on an edge-plane pyrolytic graphite electrode in 1.0 M HClO4. The β-pyrrole nitro-substituted derivatives were shown to be better catalysts than the non-nitro substituted compounds under the utilized experimental conditions.

  13. Marine cobalt resources

    USGS Publications Warehouse

    Manheim, F. T.

    1986-01-01

    Ferromanganese oxides in the open oceans are more enriched in cobalt than any other widely distributed sediments or rocks. Concentrations of cobalt exceed 1 percent in ferromanganese crusts on seamounts, ocean ridges, and other raised areas of the ocean. The cobalt-rich crusts may be the slowest growing of any earth material, accumulating one molecular layer every 1 to 3 months. Attention has been drawn to crusts as potential resources because they contain cobalt, manganese, and platinum, three of the four priority strategic metals for the United States. Moreover, unlike abyssal nodules, whose recovery is complicated by their dominant location in international waters, some of the most cobalt-rich crusts occur within the exclusive economic zone of the United States and other nations. Environmental impact statements for crust exploitation are under current development by the Department of the Interior.

  14. A Green Preconcentration Method for Determination of Cobalt and Lead in Fresh Surface and Waste Water Samples Prior to Flame Atomic Absorption Spectrometry

    PubMed Central

    Naeemullah; Kazi, Tasneem Gul; Shah, Faheem; Afridi, Hassan Imran; Khan, Sumaira; Arian, Sadaf Sadia; Brahman, Kapil Dev

    2012-01-01

    Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead (Pb) in fresh and wastewater samples. The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant. Experiments were conducted to assess the effect of different chemical variables such as pH, amounts of reagents (oxine and Triton X-114), temperature, incubation time, and sample volume. After phase separation, based on the cloud point, the surfactant-rich phase was diluted with acidic ethanol prior to its analysis by the flame atomic absorption spectrometry (FAAS). The enhancement factors 70 and 50 with detection limits of 0.26 μg L−1 and 0.44 μg L−1 were obtained for Co and Pb, respectively. In order to validate the developed method, a certified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with the certified values. The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and waste water sample. PMID:23227429

  15. Crystal structure of bis-(azido-κN)bis[2,5-bis(pyridin-2-yl)-1,3,4-thia-diazole-κ(2) N (2),N (3)]cobalt(II).

    PubMed

    Laachir, Abdelhakim; Bentiss, Fouad; Guesmi, Salaheddine; Saadi, Mohamed; El Ammari, Lahcen

    2015-05-01

    In the mononuclear title complex, [Co(N3)2(C12H8N4S)2], the cobalt(II) atom is located on an inversion centre and displays an axially weakly compressed octa-hedral coordination geometry. The equatorial positions are occupied by the N atoms of two 2,5-bis-(pyridin-2-yl)-1,3,4-thia-diazole ligands, whereas the axial positions are occupied by N atoms of the azide anions. The thia-diazole and pyridine rings linked to the metal are almost coplanar, with a maximum deviation from the mean plane of 0.0273 (16) Å. The cohesion of the crystal is ensured by weak C-H⋯N hydrogen bonds and by π-π inter-actions between pyridine rings [inter-centroid distance = 3.6356 (11) Å], forming a layered arrangement parallel to (001). The structure of the title compound is isotypic with that of the analogous nickel(II) complex [Laachir et al. (2013 ▶). Acta Cryst. E69, m351-m352].

  16. Crystal structure of bis­(azido-κN)bis[2,5-bis(pyridin-2-yl)-1,3,4-thia­diazole-κ2 N 2,N 3]cobalt(II)

    PubMed Central

    Laachir, Abdelhakim; Bentiss, Fouad; Guesmi, Salaheddine; Saadi, Mohamed; El Ammari, Lahcen

    2015-01-01

    In the mononuclear title complex, [Co(N3)2(C12H8N4S)2], the cobalt(II) atom is located on an inversion centre and displays an axially weakly compressed octa­hedral coordination geometry. The equatorial positions are occupied by the N atoms of two 2,5-bis­(pyridin-2-yl)-1,3,4-thia­diazole ligands, whereas the axial positions are occupied by N atoms of the azide anions. The thia­diazole and pyridine rings linked to the metal are almost coplanar, with a maximum deviation from the mean plane of 0.0273 (16) Å. The cohesion of the crystal is ensured by weak C—H⋯N hydrogen bonds and by π–π inter­actions between pyridine rings [inter­centroid distance = 3.6356 (11) Å], forming a layered arrangement parallel to (001). The structure of the title compound is isotypic with that of the analogous nickel(II) complex [Laachir et al. (2013 ▸). Acta Cryst. E69, m351–m352]. PMID:25995853

  17. Study of a series of cobalt(II) sulfonamide complexes: Synthesis, spectroscopic characterization, and microbiological evaluation against M. tuberculosis. Crystal structure of [Co(sulfamethoxazole)2(H2O)2]·H2O

    NASA Astrophysics Data System (ADS)

    Mondelli, Melina; Pavan, Fernando; de Souza, Paula C.; Leite, Clarice Q.; Ellena, Javier; Nascimento, Otaciro R.; Facchin, Gianella; Torre, María H.

    2013-03-01

    Nowadays, the research for new and better antimicrobial compounds is an important field due to the increase of immunocompromised patients, the use of invasive medical procedures and extensive surgeries, among others, that can affect the incidence of infections. Another big problem associated is the occurrence of drug-resistant microbial strains that impels a ceaseless search for new antimicrobial agents. In this context, a series of heterocyclic-sulfonamide complexes with Co(II) was synthesized and characterized with the aim of obtaining new antimicrobial compounds. The structural characterization was performed using different spectroscopic methods (UV-Vis, IR, and EPR). In spite of the fact that the general stoichiometry for all the complexes was Co(sulfonamide)2·nH2O, the coordination atoms were different depending on the coordinated sulfonamide. The crystal structure of [Co(sulfamethoxazole)2(H2O)2]·H2O was obtained by X-ray diffraction showing that Co(II) is in a slightly tetragonal distorted octahedron where sulfamethoxazole molecules act as a head-to-tail bridges between two cobalt atoms, forming polymeric chains. Besides, the activity against Mycobacterium tuberculosis, one of the responsible for tuberculosis, and the cytotoxicity on J774A.1 macrophage cells were evaluated.

  18. Isostructural dinuclear phenoxo-/acetato-bridged manganese(II), cobalt(II), and zinc(II) complexes with labile sites: kinetics of transesterification of 2-hydroxypropyl-p-nitrophenylphosphate.

    PubMed

    Arora, Himanshu; Barman, Suman K; Lloret, Francesc; Mukherjee, Rabindranath

    2012-05-21

    Using the dinucleating phenol-based ligand 2,6-bis[3-(pyridin-2-yl)pyrazol-1-ylmethyl]-4-methylphenol] (HL(2)), in its deprotonated form, the six new dinuclear complexes [M(II)(2)(L(2))(μ-O(2)CMe)(2)(MeCN)(2)][PF(6)] (M = Mn (2a), Co (3a), Zn (4a)) and [M(II)(2)(L(2))(μ-O(2)CMe)(2)(MeCN)(2)][BPh(4)] (M = Mn (2b), Co (3b), Zn (4b)) have been synthesized. Crystallographic analyses on 2b·2MeCN, 3b·2MeCN, and 4b·2MeCN reveal that these complexes have closely similar μ-phenoxo bis(μ-carboxylato) structures. The physicochemical properties (absorption and ESI-MS spectral data, 2a,b, 3a,b, and 4a,b; (1)H NMR, 4a,b) of the cations of 2a-4a are identical with those of 2b-4b. Each metal ion is terminally coordinated by a pyrazole nitrogen and a pyridyl nitrogen from a 3-(pyridin-2-yl)pyrazole unit and a solvent molecule (MeCN). Thus, each metal center assumes distorted-octahedral M(II)N(3)O(3) coordination. Temperature-dependent magnetic studies on Mn(II) and Co(II) dimers reveal the presence of intramolecular antiferromagnetic (J = -8.5 cm(-1)) for 2b and ferromagnetic exchange coupling (J = +2.51 cm(-1)) for 3b, on the basis of the Hamiltonian H = -JS(1)·S(2). The exchange mechanism is discussed on the basis of magneto-structural parameters (M···M distance). Spectroscopic properties of the complexes have also been investigated. The pH titration and kinetics of phosphatase (transesterification) activity on 2-hydroxypropyl-p-nirophenylphosphate (HPNP) were studied in MeOH/H(2)O (33%, v/v) with 2a-4a, due to solubility reasons. This comparative kinetic study revealed the effect of the metal ion on the rate of hydrolysis of HPNP, which has been compared with what we recently reported for [Ni(II)(2)(L(2))(μ-O(2)CMe)(2)(MeOH)(H(2)O)][ClO(4)] (1a). The efficacy in the order of conversion of substrate to product (p-nitrophenolate ion) follows the order 4a > 3a > 2a > 1a, under identical experimental conditions. Notably, this trend follows the decrease of pK(a) values of

  19. Samarium/Cobalt Magnets

    NASA Technical Reports Server (NTRS)

    Das, D.; Kumar, K.; Frost, R.; Chang, C.

    1985-01-01

    Intrinsic magnetic coercivities of samarium cobalt magnets made to approach theoretical limit of 350 kA/m by carefully eliminating oxygen from finished magnet by hot isostatic pressing (HIP). HIP process viable alternative to currently used sintering process.

  20. Simple and sensitive detection method for Cobalt(II) in water using CePO4:Tb3+ nanocrystals as fluorescent probes.

    PubMed

    Chen, Hongqi; Yuan, Fei; Xu, Juan; Zhang, Yiyang; Wu, Yong; Wang, Lun

    2013-04-15

    A simple and sensitive method for detecting cobalt by synchronous fluorescence spectrometry technique with a novel fluorescence probe CePO4:Tb(3+) has been developed. CePO4:Tb(3+) nanocrystals were synthesized in aqueous solutions and characterized by transmission electron microscopy, electron diffraction pattern spectroscopy and spectrofluorometry. When Δλ=210 nm, the selected synchronous fluorescence is produced at 284 nm. CePO4:Tb(3+) nanocrystals were negatively charged under weakly basic conditions (pH=8.2), which can interact with Co(2+) via electrostatic interaction. Moreover, there is the spectrum overlap between the emission wavelength of CePO4:Tb(3+) NCs and the absorbance of Co(2+). So the energy transfer would occur, leading to the quenching phenomenon. The quenching equation of the system was agreed with the Stern-Volmer equation. The linear range and detection limit of Co(2+) were 5-1.8 μM and 3.5 nM, respectively. The method is successfully applied to the quantification of Co(2+) in water samples.

  1. Isolation and (111)In-Oxine Labeling of Murine NK Cells for Assessment of Cell Trafficking in Orthotopic Lung Tumor Model.

    PubMed

    Malviya, Gaurav; Nayak, Tapan; Gerdes, Christian; Dierckx, Rudi A J O; Signore, Alberto; de Vries, Erik F J

    2016-04-04

    A noninvasive in vivo imaging method for NK cell trafficking is essential to gain further understanding of the pathogenesis of NK cell mediated immune response to the novel cancer treatment strategies, and to discover the homing sites and physiological distribution of NK cells. Although human NK cells can be labeled for in vivo imaging, little is known about the murine NK cell labeling and its application in animal models. This study describes the isolation and ex vivo radiolabeling of murine NK cells for the evaluation of cell trafficking in an orthotopic model of human lung cancer in mice. Scid-Tg(FCGR3A)Blt transgenic SCID mice were used to isolate NK cells from mouse splenocytes using the CD49b (DX5) MicroBeads positive selection method. The purity and viability of the isolated NK cells were confirmed by FACS analysis. Different labeling buffers and incubation times were evaluated to optimize (111)In-oxine labeling conditions. Functionality of the radiolabeled NK cell was assessed by (51)Cr-release assay. We evaluated physiological distribution of (111)In-oxine labeled murine NK cells in normal SCID mice and biodistribution in irradiated and nonirradiated SCID mice with orthotopic A549 human lung tumor lesions. Imaging findings were confirmed by histology. Results showed that incubation with 0.011 MBq of (111)In-oxine per million murine NK cells in PBS (pH 7.4) for 20 min is the best condition that provides optimum labeling efficiency without affecting cell viability and functionality. Physiological distribution in normal SCID mice demonstrated NK cells homing mainly in the spleen, while (111)In released from NK cells was excreted via kidneys into urine. Biodistribution studies demonstrated a higher lung uptake in orthotopic lung tumor-bearing mice than control mice. In irradiated mice, lung tumor uptake of radiolabeled murine NK cells decreased between 24 h and 72 h postinjection (p.i.), which was accompanied by tumor regression, while in nonirradiated mice

  2. The azide-bridged mixed-valent cobalt(II,III) compound [(CH(3))(3)NH](2)[CoCo(2)(N(3))(10)].

    PubMed

    Liu, Yan-Ju; Li, Yu-Xian; Xu, Min; Wang, Xia

    2010-12-04

    The crystal structure of the title compound, poly[bis-(tri-methyl-ammonium) hexa-μ(1,1)-azido-tetra-azido-tricobalt-ate(II,III)], [(CH(3))(3)NH](2)[Co(II)Co(III) (2)(N(3))(10)], consists of anionic chains [Co(II)Co(III) (2)(N(3))(10)](2-) extending parallel to the c axis and [(CH(3))(3)NH](+) counter-cations situated between the chains. In the anionic chain, one tetra-hedrally coordinated Co(II) atom (site symmetry 2) and two octa-hedrally coordinated Co(III) atoms are arranged alternately and are linked by μ(1,1)-azide bridges. The anionic chains and cations are connected via N-H⋯N hydrogen bonding into a three-dimensional structure.

  3. V-shaped ligand 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane and manganese(II), cobalt(II) and copper(II) complexes: Synthesis, crystal structure, DNA-binding properties and antioxidant activities.

    PubMed

    Wu, Huilu; Yang, Zaihui; Wang, Fei; Peng, Hongping; Zhang, Han; Wang, Cuiping; Wang, Kaitong

    2015-07-01

    A V-shaped ligand 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane (bebt) and its transition metal complexes, [Mn(bebt)(pic)2]·CH3OH (pic=picrate) 1, [Co(bebt)2](pic)22 and [Cu(bebt)2](pic)2·2DMF 3, have been synthesized and characterized. The coordinate forms of complexes 1 and 2 are basically alike, which can be described as six-coordinated distorted octahedron. The geometric structure around Cu(II) atom can be described as distorted tetrahedral in complex 3. The DNA-binding properties of the ligand bebt and complexes have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that bebt and complexes bind to DNA via an intercalative binding mode and the order of the binding affinity is 1<2<3

  4. Crystal structure of di­aqua­bis­(4-tert-butyl­benzoato-κO)bis­(nicotinamide-κN 1)cobalt(II) dihydrate

    PubMed Central

    Aşkın, Gülçin Şefiye; Necefoğlu, Hacali; Özkaya, Safiye; Çatak Çelik, Raziye; Hökelek, Tuncer

    2016-01-01

    The asymmetric unit of the mononuclear cobalt complex, [Co(C11H13O2)2(C6H6N2O)2(H2O)2]·2H2O, contains one half of the complex mol­ecule, one coordinating and one non-coordinating water mol­ecule, one 4-tert-butyl­benzoate (TBB) ligand and one nicotinamide (NA) ligand; the Co atom lies on an inversion centre. All ligands coordinating to the Co atom are monodentate. The four nearest O atoms around the Co atom form a slightly distorted square-planar arrangement, with the distorted octa­hedral coordination completed by the two pyridine N atoms of the NA ligands at distances of 2.1638 (11) Å. The coordinating water mol­ecules are hydrogen bonded to the carboxyl O atoms [O ⋯ O = 2.6230 (17) Å], enclosing an S(6) hydrogen-bonding motif, while inter­molecular O—H⋯O hydrogen bonds link two of the non-coordinating water mol­ecules to the coordinating water mol­ecules and NA anions. The dihedral angle between the planar carboxyl­ate group and the adjacent benzene ring is 29.09 (10)°, while the benzene and pyridine rings are oriented at a dihedral angle of 88.53 (4)°. In the crystal, O—H⋯O and N—H⋯O hydrogen bonds link the mol­ecules, enclosing R 2 2(8), R 2 2(10) and R 4 4(12) ring motifs, forming layers parallel to (001). The C and H atoms of the tert-butyl group of the TBB ligand are disordered over two sets of sites with an occupancy ratio of 0.631 (5):0.369 (5). PMID:27555924

  5. Polymeric cobalt(ii) thiolato complexes - syntheses, structures and properties of [Co(SMes)2] and [Co(SPh)2NH3].

    PubMed

    Eichhöfer, Andreas; Buth, Gernot

    2016-11-01

    Reactions of [Co(N(SiMe3)2)2thf] with 2.1 equiv. of MesSH (Mes = C6H2-2,4,6-(CH3)3) yield dark brown crystals of the one dimensional chain compound [Co(SMes)2]. In contrast reactions of [Co(N(SiMe3)2)2thf] with 2.1 equiv. of PhSH result in the formation of a dark brown almost X-ray amorphous powder of 'Co(SPh)2'. Addition of aliquots of CH3OH to the latter reaction resulted in the almost quantitative formation of crystalline ammonia thiolato complexes either [Co(SPh)2(NH3)2] or [Co(SPh)2NH3]. Single crystal XRD reveals that [Co(SPh)2NH3] forms one-dimensional chains in the crystal via μ2-SPh bridges whereas [Co(SPh)2(NH3)2] consists at a first glance of isolated distorted tetrahedral units. Magnetic measurements suggest strong antiferromagnetic coupling for the two chain compounds [Co(SMes)2] (J = -38.6 cm(-1)) and [Co(SPh)2NH3] (J = -27.1 cm(-1)). Interestingly, also the temperature dependence of the susceptibility of tetrahedral [Co(SPh)2(NH3)2] shows an antiferromagnetic transition at around 6 K. UV-Vis-NIR spectra display d-d bands in the NIR region between 500 and 2250 nm. Thermal gravimetric analysis of [Co(SPh)2(NH3)2] and [Co(SPh)2NH3] reveals two well separated cleavage processes for NH3 and SPh2 upon heating accompanied by the stepwise formation of 'Co(SPh)2' and cobalt sulfide.

  6. Novel Cobalt(II) complexes containing N,N-di(2-picolyl)amine based ligands; Synthesis, characterization and application towards methyl methacrylate polymerisation

    NASA Astrophysics Data System (ADS)

    Ahn, Seoung Hyun; Choi, Sang-Il; Jung, Maeng Joon; Nayab, Saira; Lee, Hyosun

    2016-06-01

    The reaction of [CoCl2·6H2O] with N‧-substituted N,N-di(2-picolyl)amine ligands such as 1-cyclohexyl-N,N-bis(pyridin-2-ylmethyl)methanamine (LA), 2-methoxy-N,N-bis(pyridin-2-ylmethyl)ethan-1-amine (LB), and 3-methoxy-N,N-bis(pyridin-2-ylmethyl)propan-1-amine (LC), yielded [LnCoCl2] (Ln = LA, LB and LC), respectively. The Co(II) centre in [LnCoCl2] (Ln = LA, and LC) adopted distorted bipyramidal geometries through coordination of nitrogen atoms of di(2-picolyl)amine moiety to the Co(II) centre along with two chloro ligands. The 6-coordinated [LBCoCl2] showed a distorted octahedral geometry, achieved through coordination of the two pyridyl units, two chloro units, and bidentate coordination of nitrogen and oxygen in the N‧-methoxyethylamine to the Co(II) centre. [LCCoCl2] (6.70 × 104 gPMMA/molCo h) exhibited higher catalytic activity for the polymerisation of methyl methacrylate (MMA) in the presence of modified methylaluminoxane (MMAO) compared to rest of Co(II) complexes. The catalytic activity was considered as a function of steric properties of ligand architecture and increased steric bulk around the metal centre resulted in the decrease catalytic activity. All Co(II) initiators yielded syndiotactic poly(methylmethacrylate) (PMMA).

  7. Determination of trace cobalt(II) by adsorptive stripping voltammetry on disposable microfabricated electrochemical cells with integrated planar metal-film electrodes.

    PubMed

    Kokkinos, Christos; Economou, Anastasios; Koupparis, Michael

    2009-01-15

    This work reports the determination of trace Co(II) by adsorptive stripping voltammetry on disposable three-electrode cells with on-chip metal-film electrodes. The heart of the sensors was a bismuth-film electrode (BiFE) with Ag and Pt planar strips serving as the reference and counter electrodes, respectively. Metals were deposited on a silicon chip by sputtering while the areas of the electrodes were patterned via a metal mask. Co(II) was determined by square wave adsorptive stripping voltammetry (SWAdSV) after complexation with dimethylglyoxime (DMG). The experimental variables (the DMG concentration, the preconcentration potential, the accumulation time and the SW parameters), as well as potential interferences, were investigated. Using the selected conditions, the 3 sigma limit of detection was 0.09 microg l(-1) of Co(II) (for 90s of preconcentration) and the relative standard deviation for Co(II) was 3.8% at the 2 microg l(-1) level (n=8). The method was applied to the determination of Co(II) in a certified river water sample. These mercury-free electrochemical devices present increased scope for field analysis and mu-TAS applications.

  8. Gallium(III), cobalt(III) and copper(II) protoporphyrin IX exhibit antimicrobial activity against Porphyromonas gingivalis by reducing planktonic and biofilm growth and invasion of host epithelial cells.

    PubMed

    Olczak, Teresa; Maszczak-Seneczko, Dorota; Smalley, John W; Olczak, Mariusz

    2012-08-01

    Porphyromonas gingivalis acquires heme for growth, and initiation and progression of periodontal diseases. One of its heme acquisition systems consists of the HmuR and HmuY proteins. This study analyzed the antimicrobial activity of non-iron metalloporphyrins against P. gingivalis during planktonic growth, biofilm formation, epithelial cell adhesion and invasion, and employed hmuY, hmuR and hmuY-hmuR mutants to assess the involvement of HmuY and HmuR proteins in the acquisition of metalloporphyrins. Iron(III) mesoporphyrin IX (mesoheme) and iron(III) deuteroporphyrin IX (deuteroheme) supported planktonic growth of P. gingivalis cells, biofilm accumulation, as well as survival, adhesion and invasion of HeLa cells in a way analogous to protoheme. In contrast, cobalt(III), gallium(III) and copper(II) protoporphyrin IX exhibited antimicrobial activity against P. gingivalis, and thus represent potentially useful antibacterial compounds with which to target P. gingivalis. P. gingivalis hmuY, hmuR and hmuY-hmuR mutants showed decreased growth and infection of epithelial cells in the presence of all metalloporphyrins examined. In conclusion, the HmuY protein may not be directly involved in transport of free metalloporphyrins into the bacterial cell, but it may also play a protective role against metalloporphyrin toxicity by binding an excess of these compounds.

  9. Enhanced photovoltaic performance of nanowire dye-sensitized solar cells based on coaxial TiO2@TiO heterostructures with a cobalt(II/III) redox electrolyte.

    PubMed

    Fan, Jiandong; Fàbrega, Cristian; Zamani, Reza R; Hao, Yan; Parra, Andres; Andreu, Teresa; Arbiol, Jordi; Boschloo, Gerrit; Hagfeldt, Anders; Morante, Joan Ramon; Cabot, Andreu

    2013-10-23

    The growth of a TiO shell at the surface of TiO2 nanowires (NWs) allowed us to improve the power conversion efficiency of NW-based dye-sensitized solar cells (DSCs) by a factor 2.5. TiO2@TiO core-shell NWs were obtained by a two-step process: First, rutile-phase TiO2 NWs were hydrothermally grown. Second, a hongquiite-phase TiO shell was electrochemically deposited at the surface of the TiO2 NWs. Bare TiO2 and heterojunction TiO2@TiO NW-based DSCs were obtained using a cobalt(II/III) redox electrolyte and LEG4 as the dye. With this electrolyte/dye combination, DSCs with outstanding Voc values above 900 mV were systematically obtained. While TiO2@TiO NW-based DSCs had slightly lower Voc values than bare TiO2 NW-based DSCs, they provided 3-fold higher photocurrents, overall reaching 2.5-fold higher power conversion efficiencies. The higher photocurrents were associated with the larger surface roughness and an enhanced charge-carrier separation/transfer at the NW/dye interface.

  10. Cobalt Complexes as Antiviral and Antibacterial Agents

    DTIC Science & Technology

    2010-01-01

    keratitis, one of the major causes of blindness in industrial nations [9]. Studies using the CTC class of drugs were performed using a rabbit eye model...CTC-96 inhibits membrane fusion events preventing virus entry, CTC-96 inhibited plaque formation by VSV (vesicular stomatitis virus) and VZV...antibacterial properties of cobalt complexes have appeared in the literature, with Co(II) complexes being the most studied , presumably due to their

  11. [Co(x)Cu(1-x)(DDOP)(OH2)(NO3)](NO3): hydrogen bond-driven distortion of cobalt(II) by solid solution 'network mismatch'.

    PubMed

    Fielden, John; Long, De-Liang; Speldrich, Manfred; Kögerler, Paul; Cronin, Leroy

    2012-04-28

    Late-first row transition metal nitrate complexes of the tetradentate N-donor ligand cis-3,5-bis[(2-pyridinyleneamino]-trans-hydroxycyclohexane (DDOP) adopt a mono-cationic [M(DDOP)(H(2)O)(NO(3))](+) structure (M = Co, 1; Cu, 2; Zn, 3) in which the DDOP ligand occupies the equatorial plane. The complexes are essentially isostructural and isomorphous, allowing the Co(II) and Cu(II) complexes to co-crystallize in mixed-metal solid solutions with the formula [Co(x)Cu(1-x)(DDOP)(NO(3))(H(2)O)](NO(3)), where x = 0.4 (4), 0.1 (5), and 0.7 (6). For 4, structural and magnetochemical analysis indicate that the geometry of the octahedral Co(II) complex distorts to match that of the dominant Jahn-Teller distorted Cu(II) center. Magnetic susceptibility data of octahedral Co(II) are sensitive to ligand geometry distortions and have been analyzed accordingly, comparing 4 to the reference systems 1 and 2. Bond valence calculations have been used to estimate the relative stabilities of the six hydrogen bonded networks, suggesting that the stretching of the Co(II) coordination sphere 4 in is assisted by adoption of the most stable hydrogen bonded network; but that in 6 this is overcome by a higher loading of Co. This family of complexes therefore represent predictable metal-based tectons which can help probe the influence of secondary non-covalent interactions over metal coordination geometries and properties.

  12. Catalysis: Cobalt gets in shape

    NASA Astrophysics Data System (ADS)

    Claeys, Michael

    2016-10-01

    Solid cobalt-based catalysts are used commercially to convert carbon monoxide and hydrogen into synthetic fuels. It emerges that much more valuable chemicals can be produced by using a different form of cobalt catalyst. See Letter p.84

  13. Crystal structure of di­aqua­bis­(N,N-di­ethyl­nicotinamide-κN 1)bis­(2,4,6-tri­methyl­benzoato-κO 1)cobalt(II)

    PubMed Central

    Aşkın, Gülçin Şefiye; Necefoğlu, Hacali; Özkaya, Safiye; Çatak Çelik, Raziye; Hökelek, Tuncer

    2016-01-01

    The centrosymmetric mol­ecule in the monomeric title cobalt complex, [Co(C10H11O2)2(C10H14N2O)2(H2O)2], contains two water mol­ecules, two 2,4,6-tri­methyl­benzoate (TMB) ligands and two di­ethyl­nicotinamide (DENA) ligands. All ligands coordinate to the CoII atom in a monodentate fashion. The four O atoms around the CoII atom form a slightly distorted square-planar arrangement, with the distorted octa­hedral coordination sphere completed by two pyridine N atoms of the DENA ligands. The dihedral angle between the planar carboxyl­ate group and the adjacent benzene ring is 84.2 (4)°, while the benzene and pyridine rings are oriented at a dihedral angle of 38.87 (10)°. The water mol­ecules exhibit both intra­molecular (to the non-coordinating carboxyl­ate O atom) and inter­molecular (to the amide carbonyl O atom) O—H⋯O hydrogen bonds. The latter lead to the formation of layers parallel to (100), enclosing R 4 4(32) ring motifs. These layers are further linked via weak C—H⋯O hydrogen bonds, resulting in a three-dimensional network. One of the two ethyl groups of the DENA ligand is disordered over two sets of sites with an occupancy ratio of 0.490 (13):0.510 (13). PMID:27375874

  14. DNA-interaction and in vitro antimicrobial studies of some mixed-ligand complexes of cobalt(II) with fluoroquinolone antibacterial agent ciprofloxacin and some neutral bidentate ligands.

    PubMed

    Patel, M N; Chhasatia, M R; Gandhi, D S

    2009-05-15

    Six new mixed-ligand complexes of Co(II) with ciprofloxacin (Cip) and neutral bidentate ligands have been synthesized and characterized. Binding and cleavage of DNA with the complex were investigated using spectroscopic method, viscosity measurements and gel electrophoresis techniques. Antibacterial activity has been assayed against two Gram((-ve)) and three Gram((+ve)) microorganisms using the doubling dilution technique.

  15. Preparation of a Cobalt(II) Cage: An Undergraduate Laboratory Experiment That Produces a ParaSHIFT Agent for Magnetic Resonance Spectroscopy

    ERIC Educational Resources Information Center

    Burns, Patrick J.; Tsitovich, Pavel B.; Morrow, Janet R.

    2016-01-01

    Laboratory experiments that demonstrate the effect of paramagnetic complexes on chemical shifts and relaxation times of protons are a useful way to introduce magnetic resonance spectroscopy (MRS) probes or magnetic resonance imaging (MRI) contrast agents. In this undergraduate inorganic chemistry experiment, a paramagnetic Co(II) cage complex is…

  16. Some new chromogens for iron, cobalt, and copper Substituted hydrazidines and 1,2,4-triazines containing the ferroin group.

    PubMed

    Schilt, A A

    1966-07-01

    The spectral characteristics and solution conditions requisite for formation of the iron(II), cobalt(II), and copper(I) complexes of some newly synthesised compounds containing the ferroin functional grouping have been determined. These properties are useful for evaluation of the possible analytical effectiveness of the compounds as spectrophotometric reagents for the determination of iron, cobalt, and copper.

  17. Co(II)-mediated effects of plain and plasma immersion ion implanted cobalt-chromium alloys on the osteogenic differentiation of human mesenchymal stem cells.

    PubMed

    Schröck, Kathleen; Lutz, Johanna; Mändl, Stephan; Hacker, Michael C; Kamprad, Manja; Schulz-Siegmund, Michaela

    2015-03-01

    Medical CoCr is one of the main alloys used for metal-on-metal prosthesis in patients with total hip arthroplasty. CoCr surfaces modified by nitrogen plasma immersion ion implantation (PIII) are characterized by improved wear resistance but also showed increased Co(II) ion release under in vitro conditions. For the first time, CoCr modified by nitrogen PIII was evaluated with regard to its effect on the osteogenic differentiation of MSC. The activity of alkaline phosphatase, the expression of the osteogenic genes Runt-related transcription factor 2, osteopontin as well as integrin-binding bone sialoprotein and the production of osteocalcin and hydroxyapatite were determined. The results of our study demonstrate that Co(II) ions released from the alloy affected the osteogenic differentiation of MSC. Distinct differences in differentiation markers were found between pristine and modified alloys for osteocalcin but not for integrin-binding sialoprotein and hydroxyapatite. Interestingly, osteopontin was upregulated in naive and differentiated MSC by Co(II) ions and modified CoCr, likely through the induction of a cellular hypoxic response. The findings of this study contribute to a better understanding of possible risk factors with regard to a clinical applicability of surface modified CoCr implant materials.

  18. New topology in azide-bridged cobalt(II) complexes: the weak ferromagnet [Co(2)(N(3))(4)(Hexamethylenetetramine)(H(2)O)](n).

    PubMed

    Mautner, Franz A; Ohrström, Lars; Sodin, Beate; Vicente, Ramon

    2009-07-06

    A new polynuclear azido-bridged Co(II) compound with formula [Co(2)(N(3))(4)(HMTA)(H(2)O)](n) (1) (HMTA = hexamethylenetetramine) has been structurally and magnetically characterized. The compound 1 crystallizes in the monoclinic system C2/m space group, and consist of a complex three-dimensional system in which end-to-end and end-on azido bridging ligands between the Co(II) atoms coexist. The HMTA ligand is also linking three different Co(II) atoms. The network analysis shows for 1 a three- and six-connected network topology not previously reported. The magnetic properties of 1 are also reported, and it was found that the magnetic interactions define another new three- and four-connected net assigned as a (6.8(2))(6(4).10(2))-tfo net. In the high temperature region the chi(M) versus T plot can be fitted by using the Curie-Weiss law, and the best fit theta value is -26.6 K. For 1 magnetic ordering and spontaneous magnetization is achieved below T(c) = 15.6 K.

  19. Porous cobalt spheres for high temperature gradient magnetically assisted fluidized beds

    NASA Technical Reports Server (NTRS)

    Atwater, James E.; Akse, James R.; Jovanovic, Goran N.; Wheeler, Richard R Jr; Sornchamni, Thana

    2003-01-01

    Porous metallic cobalt spheres have been prepared as high temperature capable media for employment in gradient magnetically assisted fluidization and filtration technologies. Cobalt impregnated alginate beads are first formed by extrusion of an aqueous suspension of Co3O4 into a Co(II) chloride solution. The organic polymer is thermally decomposed yielding cobalt oxide spheres, followed by reduction to the metallic state, and densification. Cobalt beads have been produced with porosities ranging between 10 and 50%, depending upon sintering conditions. The product media have been characterized by scanning electron microscopy (SEM), nitrogen adsorption porosimetry, and vibrating sample magnetometry. c2003 Elsevier Science Ltd. All rights reserved.

  20. Porous cobalt spheres for high temperature gradient magnetically assisted fluidized beds.

    PubMed

    Atwater, James E; Akse, James R; Jovanovic, Goran N; Wheeler, Richard R; Sornchamni, Thana

    2003-02-20

    Porous metallic cobalt spheres have been prepared as high temperature capable media for employment in gradient magnetically assisted fluidization and filtration technologies. Cobalt impregnated alginate beads are first formed by extrusion of an aqueous suspension of Co3O4 into a Co(II) chloride solution. The organic polymer is thermally decomposed yielding cobalt oxide spheres, followed by reduction to the metallic state, and densification. Cobalt beads have been produced with porosities ranging between 10 and 50%, depending upon sintering conditions. The product media have been characterized by scanning electron microscopy (SEM), nitrogen adsorption porosimetry, and vibrating sample magnetometry.

  1. Porous cobalt spheres for high temperature gradient magnetically assisted fluidized beds

    SciTech Connect

    Atwater, James E.; Akse, James R.; Jovanovic, Goran N.; Wheeler, Richard R.; Sornchamni, Thana

    2003-02-20

    Porous metallic cobalt spheres have been prepared as high temperature capable media for employment in gradient magnetically assisted fluidization and filtration technologies. Cobalt impregnated alginate beads are first formed by extrusion of an aqueous suspension of Co{sub 3}O{sub 4} into a Co(II) chloride solution. The organic polymer is thermally decomposed yielding cobalt oxide spheres, followed by reduction to the metallic state, and densification. Cobalt beads have been produced with porosities ranging between 10 and 50%, depending upon sintering conditions. The product media have been characterized by scanning electron microscopy (SEM), nitrogen adsorption porosimetry, and vibrating sample magnetometry.

  2. Cobalt toxicity: chemical and radiological combined effects on HaCaT keratinocyte cell line.

    PubMed

    Gault, N; Sandre, C; Poncy, J-L; Moulin, C; Lefaix, J-L; Bresson, C

    2010-02-01

    Cobalt (Co) is an essential trace element well known as a constituent of vitamin B(12), but different compounds of Co are also described as highly toxic and/or radiotoxic for individuals or the environment. In nuclear power plants, (58)Co and (60)Co are radioactive isotopes of cobalt present as activation products of stable Co and Ni used in alloys. Skin exposure is a current occupational risk in the hard metal and nuclear industries. As biochemical and molecular cobalt-induced toxicological mechanisms are not fully identified, we investigated cobalt toxicity in a model human keratinocyte cell line, HaCaT. In this study, we propose a model to determine the in vitro chemical impact on cell viability of a soluble form of cobalt (CoCl(2)) with or without gamma-ray doses to mimic contamination by (60)Co, to elucidate the mechanisms of cobalt intracellular chemical and radiological toxicity. Intracellular cobalt concentration was determined after HaCaT cell contamination and chemical toxicity was evaluated in terms of cellular viability and clonogenic survival. We investigated damage to DNA in HaCaT cells by combined treatment with chemical cobalt and a moderate gamma-ray dose. Additive effects of cobalt and irradiation were demonstrated. The underlying mechanism of cobalt toxicity is not clearly established, but our results seem to indicate that the toxicity of Co(II) and of irradiation arises from production of reactive oxygen species.

  3. Crystal structure of aqua­tris­(isonicotinamide-κN)bis­(thio­cyanato-κN)cobalt(II) 2.5-hydrate

    PubMed Central

    Neumann, Tristan; Jess, Inke; Näther, Christian

    2016-01-01

    The asymmetric unit of the title compound, [Co(NCS)2(C6H6N2O)3(H2O)]·2.5H2O, comprises one CoII cation, three isonicotinamide ligands, two thio­cyanate anions, one aqua ligand and two water solvent mol­ecules in general positions, as well as one water solvent mol­ecule that is located on a twofold rotation axis. The CoII cations are octa­hedrally coordinated by two terminally N-bonded thio­cyanate anions, one water mol­ecule and three isonicotinamide ligands, each coordinating via the pyridine N atom. The discrete complexes are linked by inter­molecular O—H⋯O, N—H⋯O and N—H⋯S hydrogen bonding into a three-dimensional network that contains cavities in which the solvent water mol­ecules are located. The latter are linked by further O—H⋯O hydrogen bonds to the network. There are additional short contacts present in the crystal, indicative of weak C—H⋯S, C—H⋯O and C—H⋯N inter­actions. PMID:27920913

  4. Crystal structure of tetra­kis­(isonicotinamide-κN)bis­(thio­cyanato-κN)cobalt(II)–isonicotinamide–ethanol (1/2/1)

    PubMed Central

    Neumann, Tristan; Jess, Inke; Näther, Christian

    2016-01-01

    The asymmetric unit of the title compound, [Co(NCS)2(C6H6N2O)4]·2C6H6N2O·C2H5OH, comprises one CoII cation, two thio­cyanate anions, four coordinating and two solvent isonicotinamide molecules and one ethanol solvent mol­ecule. The CoII cations are octa­hedrally coordinated by four N-coordinating isonicotinamide ligands and two terminally N-bonded thio­cyanate anions. These discrete complexes are linked by inter­molecular N—H⋯O and N—H⋯S hydrogen-bonding inter­actions into a three-dimensional network. The two isonicotinamide and the ethanol solvent mol­ecules are embedded in channels of this network and are linked through further N—H⋯O and N—H⋯N hydrogen bonds to the network. The ethanol solvent mol­ecule is disordered over two sets of sites (occupancy ratio 0.6:0.4). PMID:27536386

  5. Effect of substituent on structures and catalytic properties of cobalt(II) isophthalate coordination polymers with a semi-rigid bis(benzimidazole)

    NASA Astrophysics Data System (ADS)

    Zhang, Xu; Meng, Xiang-Li; Huang, Cui-Miao; Cui, Guang-Hua

    2015-11-01

    Three Co(II) coordination polymers based on flexible bis(2-dimethylbenzimidazole) and the derivatives of the familiar isophthalate co-ligands, namely [Co(L)(ip)]n (1), [Co2(L)2(nip)2]n (2) and [Co2(L)2(tbip)2·2H2O]n (3) (L = 1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H2ip = isophthalic acid, H2nip = 5-nitroisophthalic acid, H2tbip = 5-tert-butylisophthalic acid) have been synthesized by hydrothermal methods and characterized by elemental analyses, IR spectra, thermogravimetric analyses and single-crystal X-ray diffraction. Both complexes 1 and 2 exhibit a 2-fold interpenetrating 3D network with 66-dia topology, whereas complex 3 is bridged by the L and tbip2- ligands to form a rarely tri-nodal (3,3,5) layer with 3,3,5L18 topology. The results indicate that Co(II) mixed coordination polymers structurally modulated by the substituent effect of isophthalate-involved co-ligands. In addition, the fluorescence and catalytic activity of the complexes for the degradation of methyl orange by the sodium persulfate in a Fenton-like process have been investigated.

  6. Synthesis and biophysical studies of bis-macrocyclic cobalt/copper(II) complexes having a pyridine spacer with CT DNA and 5'-GMP.

    PubMed

    Arjmand, Farukh; Aziz, Mubashira

    2009-12-01

    New bis-macrocyclic complexes of Co(III), 1, Ni(II), 2, and Cu(II), 3, containing pyridyl bridges between 13-membered macrocyclic subunits, have been synthesized via an in situ one-pot template condensation reaction (IOPTCR). The proposed structures of these new dinuclear complexes are consistent with the data obtained from elemental analysis, molar conductance, IR, EPR, UV/VIS, (1)H- and 13C-NMR, and ESI-MS. The complexes 2 and 3 possess square-planar geometry with four secondary N-atoms coordinated to the metal ion, while complex 1 reveals octahedral geometry in solution due to coordinated H(2)O molecules. DNA-Binding properties of the complexes 1 and 3 were investigated by absorption and emission titrations, cyclic voltammetry, and viscosity measurements. Complexes 1 and 3 are strong DNA binders with binding constants, K(b), of 1.64 x 10(5) and 2.05 x 10(5) M(-1), respectively. Hyperchromism, decrease in emission intensity of DNA-bound ethidium bromide (EB), and changes observed in the viscosity and cyclic voltammograms in the presence of added metal complexes reveals that the complexes bind to DNA predominantly by electrostatic attraction, substantiated by absorption titration with 5'-GMP.

  7. Cobalt catalysis involving π components in organic synthesis.

    PubMed

    Gandeepan, Parthasarathy; Cheng, Chien-Hong

    2015-04-21

    Over the last three decades, transition-metal-catalyzed organic transformations have been shown to be extremely important in organic synthesis. However, most of the successful reactions are associated with noble metals, which are generally toxic, expensive, and less abundant. Therefore, we have focused on catalysis using the abundant first-row transition metals, specifically cobalt. In this Account, we demonstrate the potential of cobalt catalysis in organic synthesis as revealed by our research. We have developed many useful catalytic systems using cobalt complexes. Overall, they can be classified into several broad types of reactions, specifically [2 + 2 + 2] and [2 + 2] cycloadditions; enyne reductive coupling; reductive [3 + 2] cycloaddition of alkynes/allenes with enones; reductive coupling of alkyl iodides with alkenes; addition of organoboronic acids to alkynes, alkenes, or aldehydes; carbocyclization of o-iodoaryl ketones/aldehydes with alkynes/electron-deficient alkenes; coupling of thiols with aryl and alkyl halides; enyne coupling; and C-H bond activation. Reactions relying on π components, specifically cycloaddition, reductive coupling, and enyne coupling, mostly afford products with excellent stereo- and regioselectivity and superior atom economy. We believe that these cobalt-catalyzed π-component coupling reactions proceed through five-membered cobaltacyclic intermediates formed by the oxidative cyclometalation of two coordinated π bonds of the substrates to the low-valent cobalt species. The high regio- and stereoselectivity of these reactions are achieved as a result of the electronic and steric effects of the π components. Mostly, electron-withdrawing groups and bulkier groups attached to the π bonds prefer to be placed near the cobalt center of the cobaltacycle. Most of these transformations proceed through low-valent cobalt complexes, which are conveniently generated in situ from air-stable Co(II) salts by Zn- or Mn-mediated reduction

  8. Coordination Complexes of Cobalt.

    ERIC Educational Resources Information Center

    Williams, Gregory M.; And Others

    1989-01-01

    Described is an experiment involving the synthesis and spectral studies of cobalt complexes that not only give general chemistry students an introduction to inorganic synthesis but allows them to conduct a systematic study on the effect of different ligands on absorption spectra. Background information, procedures, and experimental results are…

  9. Halogenation of cobalt dicarbollide

    DOEpatents

    Hurlburt, P.K.; Abney, K.D.; Kinkead, S.A.

    1997-05-20

    A method for selectively adding chlorine, bromine, or iodine to cobalt dicarbollide anions by means of electrophilic substitution reactions. Halogens are added only to the B10 and B10{prime} positions of the anion. The process involves use of hypohalous acid or N-halosuccinimide or gaseous chlorine in the presence of iron. 1 fig.

  10. Halogenation of cobalt dicarbollide

    DOEpatents

    Hurlburt, Paul K.; Abney, Kent D.; Kinkead, Scott A.

    1997-01-01

    A method for selectively adding chlorine, bromine, or iodine to cobalt dicarbollide anions by means of electrophilic substitution reactions. Halogens are added only to the B10 and B10' positions of the anion. The process involves use of hypohalous acid or N-halosuccinimide or gaseous chlorine in the presence of iron.

  11. A new direction in dye-sensitized solar cells redox mediator development: in situ fine-tuning of the cobalt(II)/(III) redox potential through Lewis base interactions.

    PubMed

    Kashif, Muhammad K; Axelson, Jordan C; Duffy, Noel W; Forsyth, Craig M; Chang, Christopher J; Long, Jeffrey R; Spiccia, Leone; Bach, Udo

    2012-10-10

    Dye-sensitized solar cells (DSCs) are an attractive renewable energy technology currently under intense investigation. In recent years, one area of major interest has been the exploration of alternatives to the classical iodide/triiodide redox shuttle, with particular attention focused on cobalt complexes with the general formula [Co(L)(n)](2+/3+). We introduce a new approach to designing redox mediators that involves the application of [Co(PY5Me(2))(MeCN)](2+/3+) complexes, where PY5Me(2) is the pentadentate ligand, 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine. It is shown, by X-ray crystallography, that the axial acetonitrile (MeCN) ligand can be replaced by more strongly coordinating Lewis bases (B) to give complexes with the general formula [Co(PY5Me(2))(B)](2+/3+), where B = 4-tert-butylpyridine (tBP) or N-methylbenzimidazole (NMBI). These commonly applied DSC electrolyte components are used for the first time to fine-tune the potential of the redox couple to the requirements of the dye through coordinative interactions with the Co(II/III) centers. Application of electrolytes based on the [Co(PY5Me(2))(NMBI)](2+/3+) complex in combination with a commercially available organic sensitizer has enabled us to attain DSC efficiencies of 8.4% and 9.2% at a simulated light intensity of 100% sun (1000 W m(-2) AM1.5 G) and at 10% sun, respectively, higher than analogous devices applying the [Co(bpy)(3)](2+/3+) redox couple, and an open circuit voltage (V(oc)) of almost 1.0 V at 100% sun for devices constructed with the tBP complex.

  12. OMCVD of cobalt and cobalt silicide

    NASA Astrophysics Data System (ADS)

    Dormans, G. J. M.; Meekes, G. J. B. M.; Staring, E. G. J.

    1991-11-01

    Cobalt and cobalt silicide layers were deposited by OMCVD using the Co precursors Co(C 5H 5) 2, Co 2(CO) 8, Co(C 5H 5)(CO) 2 and CoCF 3(CO) 4, and the Si precursors SiH 4 and Si 2H 6. Strongly textured (111)-β Co layers were grown from Co(C 5H 5) 2, Co(C 5H 5)(CO) 2 and CoCF 3(CO) 4 at temperatures above 300°C in H 2 at atmospheric pressure. Growth from Co(C 5H 5) 2 is inhibited on Si substrates. For temperatures ≥600°C the Co layers deposited from Co(C 5H 5)(CO) 2 react with the Si(100) substrate to form CoSi 2(00 l) aligned with the substrate orientation. Co 2(CO) 8 gives amorphous Co between 200 and 300°C. The upper temperature is set by the occurrence of homogeneous gas-phase reactions at atmospheric reactor pressure. Cobalt silicide layers can be grown from CO 2(CO) 8 and (di)silane at temperatures between 200 and 400°C. The Co/Si ratio in the layers decreases with increasing temperature and is independent of the gas-phase Co/Si ratio. Stoichiometric CoSi 2 is obtained at ~ 300°C. Both Co(C 5H 5) 2 and Co(C 5H 5)(CO) 2 react with (di)silane, leading to the incorporation of carbon in the layer. The Co/Si ration and the carbon content in the layers are practically independent of the deposition conditions. With CoCF 3(CO) 4 no contamination-free silicide could be grown. The carbon incorporation with Co(C 5H 5) 2 and Co(C 5H 5)(CO) 2 can be avoided by a pulsed growth method in which the Co precursor and the Si precursor are introduced alternately into the reactor. With Co(C 5H 5) 2 the growth is then inhibited on Si substrates.

  13. Synthesis and characterization of a series of transition metal complexes with a new symmetrical polyoxaaza macroacyclic Schiff base ligand: X-ray crystal structure of cobalt(II) and nickel(II) complexes and their antibacterial properties

    NASA Astrophysics Data System (ADS)

    Keypour, Hassan; Shayesteh, Maryam; Rezaeivala, Majid; Chalabian, Firoozeh; Valencia, Laura

    2013-01-01

    A new symmetrical [N4O2] hexadentate Schiff base ligand, (E)-N-(pyridin-2-ylmethylene)-2-(3-(2-((E)-pyridin-2-lmethyleneamino)phenoxy)naphthalen-2-yloxy)benzenamine, abbreviated to L, and its complexes of Ni(II), Cu(II), Zn(II), Co(II), Cd(II) and Mn(II) have been synthesized in the presence of metal ions. The complexes were structurally characterized by elemental analyses, IR, UV-Vis, NMR and molar conductivity. The crystal structures of two complexes, [NiL(ONO2)2]·2H2O and [CoLCl2]CH3OH·0.5H2O, have been determined by a single crystal X-ray diffraction study. In these complexes, the ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms. The metal ions complete their six coordination with two coordinated nitrate or chloride ions, forming a distorted octahedral geometry. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Enterococcus faecalis, Bacillus cereus and Staphylococcus epid and also against the three Gram-negative bacteria: Citrobacter freundii, Enterobacter aerogenes and Salmonella typhi. The activity data show that the complexes are more potent antibacterials than the parent Schiff base.

  14. Synthesis and characterization of a series of transition metal complexes with a new symmetrical polyoxaaza macroacyclic Schiff base ligand: X-ray crystal structure of cobalt(II) and nickel(II) complexes and their antibacterial properties.

    PubMed

    Keypour, Hassan; Shayesteh, Maryam; Rezaeivala, Majid; Chalabian, Firoozeh; Valencia, Laura

    2013-01-15

    A new symmetrical [N4O2] hexadentate Schiff base ligand, (E)-N-(pyridin-2-ylmethylene)-2-(3-(2-((E)-pyridin-2-lmethyleneamino)phenoxy)naphthalen-2-yloxy)benzenamine, abbreviated to L, and its complexes of Ni(II), Cu(II), Zn(II), Co(II), Cd(II) and Mn(II) have been synthesized in the presence of metal ions. The complexes were structurally characterized by elemental analyses, IR, UV-Vis, NMR and molar conductivity. The crystal structures of two complexes, [NiL(ONO2)2]·2H2O and [CoLCl2]CH3OH·0.5H2O, have been determined by a single crystal X-ray diffraction study. In these complexes, the ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms. The metal ions complete their six coordination with two coordinated nitrate or chloride ions, forming a distorted octahedral geometry. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Enterococcus faecalis, Bacillus cereus and Staphylococcus epid and also against the three Gram-negative bacteria: Citrobacter freundii, Enterobacter aerogenes and Salmonella typhi. The activity data show that the complexes are more potent antibacterials than the parent Schiff base.

  15. Synthesis, physicochemical analysis of two new hemilabile ether-phosphine ligands and their first stable bis-ether-phosphine/cobalt(II) tetrahedral complexes

    NASA Astrophysics Data System (ADS)

    Warad, Ismail; Barakat, Assem

    2017-04-01

    New tridentate ether-phosphine {P, 2O} and ether-phosphine oxide {OP, 2O} ligands with P and O donor-atoms have been synthesized starting from ClCH2CH(OCH3)2. The oxidation process of Ph2PCH2CH(OCH3)2 to its oxide derivative Ph2P(dbnd O)CH2CH(OCH3)2 was monitored by 31P NMR for the first time. The desired ligands and their Co(II) complexes structures were deduced from IR, EA, MS, NMR, UV-Vis., TG/DTG and XRD physical measurements. The tridentate chelating coordination behavior of the ether-phosphine wasn't detected leading only to the mono-dentate coordination mode through the phosphorous atoms to set up a X2Co[η1-Ph2PCH2CH(OCH3)2]2 as final isomer formula (X = Cl or Br). The Cl2Co[η1-Ph2PCH2CH(OCH3)2]2 isomer belongs to complex 1 was supported by single crystal measurement. Polar/non-polar intermolecular short contacts were detected by XRD and Hirshfeld surface theoretical analysis.

  16. Application of aqueous two-phase systems for the development of a new method of cobalt(II), iron(III) and nickel(II) extraction: a green chemistry approach.

    PubMed

    Patrício, Pamela da Rocha; Mesquita, Maiby Cabral; da Silva, Luis Henrique Mendes; da Silva, Maria C Hespanhol

    2011-10-15

    We have investigated the extraction behavior of the metallic ions Co(II), Fe(III) and Ni(II) as a function of the amount of potassium thiocyanate used as an extracting agent, using the following aqueous two-phase systems (ATPS): PEO + (NH(4))(2)SO(4) + H(2)O, PEO + Li(2)SO(4) + H(2)O, L35 + (NH(4))(2)SO(4) + H(2)O and L35 + (Li)(2)SO(4)+H(2)O. Metal extraction from the salt-rich phase to the polymer-rich phase is affected by the following parameters: amount of added extractant, pH, and the nature of the electrolyte and polymer that forms the ATPS. Maximal extraction percentages were obtained for Co(II) (99.8%), Fe(III) (12.7%) and Ni(II) (3.17%) when the ATPS was composed of PEO1500 + (NH(4))(2)SO(4) + H(2)O containing 1.4 mmol of KSCN at pH 4.0, providing separation factors as high as S(Co, Fe) = 3440 and S(Co, Ni) = 15,300. However, when the same ATPS was used at pH 2.0, the maximal extraction percentages for iron and nickel were 99.5% and 4.34%, respectively, with S(Fe, Ni) equal to 4380. The proposed technique was shown to be efficient in the extraction of Co(II) and Fe(III), with large viability for the selective separation of Co(II) and Fe(III) ions in the presence of Ni(II).

  17. Synthesis and Characterization of Cobalt(III), Nickel(II) and Copper(II) Mononuclear Complexes with the Ligand 1,3-bis[(2-aminoethyl)amino]-2-propanol and Their Catalase-Like Activity.

    PubMed

    Pires, Bianca M; Silva, Daniel M; Visentin, Lorenzo C; Rodrigues, Bernardo L; Carvalho, Nakédia M F; Faria, Roberto B

    2015-01-01

    In this work, we present the synthesis and characterization of two new mononuclear complexes with the ligand 1,3-bis[(2-aminoethyl)amino]-2-propanol (HL), [Co(L)(H2O)](ClO4)2 (1), [Ni(HL)](ClO4)2 (2), as well as the known complex [Cu(HL)](ClO4)2 (3) for comparison. Their abilities to catalyze the dismutation of H2O2 and the oxidation of cyclohexane were investigated. The complexes were characterized by X-ray diffraction, elemental analysis, electronic and infrared spectroscopy, cyclic voltammetry, electrospray ionization mass spectrometry (ESI-MS) and conductivity measurements. The X-ray structures showed that the nickel (2) and copper (3) complexes are tetracoordinated, with the metal ion bound to the nitrogen atoms of the ligand. On the other hand, the cobalt complex (1) is hexacoordinated, possessing additional bonds to the alkoxo group of the ligand and to a water molecule. Neither of the complexes was able to catalyze the oxidation of cyclohexane, but all of them exhibited catalase-like activity, following Michaelis-Menten kinetics, which suggest resemblance with the catalase natural enzymes. The catalytic activity followed the order: [Ni(HL)](ClO4)2 (2) > [Cu(HL)](ClO4)2 (3) > [Co(L)(H2O)](ClO4)2 (1). As far as we know, this is the first description of a nickel complex presenting a significant catalase-like activity.

  18. Synthesis and Characterization of Cobalt(III), Nickel(II) and Copper(II) Mononuclear Complexes with the Ligand 1,3-bis[(2-aminoethyl)amino]-2-propanol and Their Catalase-Like Activity

    PubMed Central

    Silva, Daniel M.; Visentin, Lorenzo C.; Rodrigues, Bernardo L.

    2015-01-01

    In this work, we present the synthesis and characterization of two new mononuclear complexes with the ligand 1,3-bis[(2-aminoethyl)amino]-2-propanol (HL), [Co(L)(H2O)](ClO4)2 (1), [Ni(HL)](ClO4)2 (2), as well as the known complex [Cu(HL)](ClO4)2 (3) for comparison. Their abilities to catalyze the dismutation of H2O2 and the oxidation of cyclohexane were investigated. The complexes were characterized by X-ray diffraction, elemental analysis, electronic and infrared spectroscopy, cyclic voltammetry, electrospray ionization mass spectrometry (ESI-MS) and conductivity measurements. The X-ray structures showed that the nickel (2) and copper (3) complexes are tetracoordinated, with the metal ion bound to the nitrogen atoms of the ligand. On the other hand, the cobalt complex (1) is hexacoordinated, possessing additional bonds to the alkoxo group of the ligand and to a water molecule. Neither of the complexes was able to catalyze the oxidation of cyclohexane, but all of them exhibited catalase-like activity, following Michaelis-Menten kinetics, which suggest resemblance with the catalase natural enzymes. The catalytic activity followed the order: [Ni(HL)](ClO4)2 (2) > [Cu(HL)](ClO4)2 (3) > [Co(L)(H2O)](ClO4)2 (1). As far as we know, this is the first description of a nickel complex presenting a significant catalase-like activity. PMID:26379038

  19. Towards accurate estimates of the spin-state energetics of spin-crossover complexes within density functional theory: a comparative case study of cobalt(II) complexes.

    PubMed

    Vargas, Alfredo; Krivokapic, Itana; Hauser, Andreas; Lawson Daku, Latévi Max

    2013-03-21

    We report a detailed DFT study of the energetic and structural properties of the spin-crossover Co(ii) complex [Co(tpy)(2)](2+) (tpy = 2,2':6',2''-terpyridine) in the low-spin (LS) and the high-spin (HS) states, using several generalized gradient approximation and hybrid functionals. In either spin-state, the results obtained with the functionals are consistent with one another and in good agreement with available experimental data. Although the different functionals correctly predict the LS state as the electronic ground state of [Co(tpy)(2)](2+), they give estimates of the HS-LS zero-point energy difference which strongly depend on the functional used. This dependency on the functional was also reported for the DFT estimates of the zero-point energy difference in the HS complex [Co(bpy)(3)](2+) (bpy = 2,2'-bipyridine) [A. Vargas, A. Hauser and L. M. Lawson Daku, J. Chem. Theory Comput., 2009, 5, 97]. The comparison of the and estimates showed that all functionals correctly predict an increase of the zero-point energy difference upon the bpy → tpy ligand substitution, which furthermore weakly depends on the functionals, amounting to . From these results and basic thermodynamic considerations, we establish that, despite their limitations, current DFT methods can be applied to the accurate determination of the spin-state energetics of complexes of a transition metal ion, or of these complexes in different environments, provided that the spin-state energetics is accurately known in one case. Thus, making use of the availability of a highly accurate ab initio estimate of the HS-LS energy difference in the complex [Co(NCH)(6)](2+) [L. M. Lawson Daku, F. Aquilante, T. W. Robinson and A. Hauser, J. Chem. Theory Comput., 2012, 8, 4216], we obtain for [Co(tpy)(2)](2+) and [Co(bpy)(3)](2+) best estimates of and , in good agreement with the known magnetic behaviour of the two complexes.

  20. Cobalt sorption in silica-pillared clays.

    PubMed

    Sampieri, A; Fetter, G; Bosch, P; Bulbulian, S

    2006-01-03

    Silicon pillared samples were prepared following conventional and microwave irradiation methods. The samples were characterized and tested in cobalt sorption. Ethylenediammine was added before cobalt addition to improve the amount of cobalt retained. The amount of cobalt introduced in the original clay in the presence of ethylenediammine was the highest. In calcined pillared clays the cobalt retention with ethylenediammine was lower (ca. 40%). In all cases the presence of ethylenediammine increased twice the amount of cobalt sorption measured for aqueous solutions.

  1. Cobalt ion-containing epoxies

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K.

    1983-01-01

    Varying concentrations of an organometallic cobalt complex were added to an epoxy system currently used by the aerospace industry as a composite matrix resin. Methods for combining cobalt (III) acetylacetonate with a tetraglycidyl 4,4 prime - diaminodiphenylmethane-based epoxy were investigated. The effects of increasing cobalt ion concentration on the epoxy cure were demonstrated by epoxy gel times and differential scanning calorimetry cure exotherms. Analysis on cured cobalt-containing epoxy castings included determination of glass transition temperatures by thermomechanical analysis, thermooxidative stabilities by thermogravimetric analysis, and densities in a density gradient column. Flexural strength and stiffness were also measured on the neat resin castings.

  2. Synthesis, structures and properties of the new lithium cobalt(II) phosphate Li{sub 4}Co(PO{sub 4}){sub 2}

    SciTech Connect

    Glaum, R.; Gerber, K.; Schulz-Dobrick, M.

    2012-04-15

    {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} has been synthesized and crystallized by solid-state reactions. The new phosphate crystallizes in the monoclinic system (P2{sub 1}/a, Z=4, a=8.117(3) Angstrom-Sign , b=10.303(8) Angstrom-Sign , c=8.118(8) Angstrom-Sign , {beta}=104.36(8) Angstrom-Sign ) and is isotypic to {alpha}-Li{sub 4}Zn(PO{sub 4}){sub 2}. The structure of {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} has been determined from single-crystal X-ray diffraction data {l_brace}R{sub 1}=0.040, wR{sub 2}=0.135, 2278 unique reflections with F{sub o}>4{sigma}(F{sub o}){r_brace}. The crystal structure, which might be regarded as a superstructure of the wurtzite structure type, is build of layers of regular CoO{sub 4}, PO{sub 4} and Li1O{sub 4} tetrahedra. Lithium atoms Li2, Li3 and Li4 are located between these layers. Thermal investigations by in-situ XRPD, DTA/TG and quenching experiments suggest decomposition followed by formation and phase transformation of Li{sub 4}Co(PO{sub 4}){sub 2}: {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} Long-Rightwards-Double-Arrow {sup 442 Degree-Sign C}{beta}-Li{sub 3}PO{sub 4}+LiCoPO{sub 4} Rightwards-Harpoon-Over-Leftwards-Harpoon {sup 773 Degree-Sign C}{beta}-Li{sub 4}Co(PO{sub 4}){sub 2} Long-Rightwards-Double-Arrow {sup quenchingto25 Degree-Sign C}{alpha}-Li{sub 4} Co(PO{sub 4}){sub 2} According to HT-XRPD at {theta}=850 Degree-Sign C{beta}-Li{sub 4}Co(PO{sub 4}){sub 2} (Pnma, Z=2, 10.3341(8) A, b=6.5829(5) A, c=5.0428(3) Angstrom-Sign ) is isostructural to {gamma}-Li{sub 3}PO{sub 4}. The powder reflectance spectrum of {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} shows the typical absorption bands for the tetrahedral chromophore [Co{sup II}O{sub 4}]. - Graphical abstract: The complex formation and decomposition behavior of Li{sub 4}Co(PO{sub 4}){sub 2} with temperature has been elucidated. The crystal structure of its {alpha}-phase was determined from single crystal data, HT-XRPD allowed derivation of a structure model for the {beta}-phase. Both

  3. Synthesis and structural characterization of silver(I), aluminium(III) and cobalt(II) complexes with 4-isopropyltropolone (hinokitiol) showing noteworthy biological activities. Action of silver(I)-oxygen bonding complexes on the antimicrobial activities.

    PubMed

    Nomiya, Kenji; Yoshizawa, Akira; Tsukagoshi, Ken; Kasuga, Noriko Chikaraishi; Hirakawa, Shoko; Watanabe, Jun

    2004-01-01

    Through two unequivalent oxygen donor atoms of the hinokitiol (Hhino; C10H12O2; 4-isopropyltropolone) ligand that showed noteworthy biological activities, the dimeric, silver(I)-oxygen bonding complex [Ag(hino)]2 1, the monomeric aluminium(III) complex [Al(hino)3].0.5H2O 4 and the cobalt(II) complex "[Co(hino)2]2.H2O" 6 were synthesized and characterized with elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), FTIR and solution (1H and 13C) NMR spectroscopy. The crystal structure of 1 was determined by Rietveld analysis based on X-ray powder diffraction (XPD) data and those of [Al(hino)3].MeOH 4a and [Co(hino)2(EtOH)]2 6a, being obtained as yellow block crystals and red platelet crystals, respectively, by crystallization of 4 and 6, were determined by single-crystal X-ray analysis. The antimicrobial activities of 1, 4 and 6, evaluated with minimum inhibitory concentration (MIC; microg ml(-1)), were compared with those of other metal complexes (M=Na, Li, Cs, Ca, V, Zn) with the hino- ligand. The antimicrobial activities observed in the alkali-metal salts strongly suggested that they were attributed to the effect of the anionic hino- species. The antimicrobial activities of 1 were significantly enhanced, whereas those of other metal complexes were suppressed, compared with those of the neutral Hhino and anionic hino- molecules. The antimicrobial activities observed in 1 were comparable with those of other recently found silver(I)-oxygen bonding complexes, the ligands of which had no activity. Thus, it is proposed that the antimicrobial activities of the silver(I)-oxygen bonding complexes are due to a direct interaction or complexation of the silver(I) ion with biological ligands such as protein, enzyme and membrane, and the coordinating ligands of the silver(I) complexes play the role of a carrier of the silver(I) ion to the biological system.

  4. Cobalt-phosphate oxygen-evolving compound.

    PubMed

    Kanan, Matthew W; Surendranath, Yogesh; Nocera, Daniel G

    2009-01-01

    The utilization of solar energy on a large scale requires efficient storage. Solar-to-fuels has the capacity to meet large scale storage needs as demonstrated by natural photosynthesis. This process uses sunlight to rearrange the bonds of water to furnish O2 and an H2-equivalent. We present a tutorial review of our efforts to develop an amorphous cobalt-phosphate catalyst that oxidizes water to O2. The use of earth-abundant materials, operation in water at neutral pH, and the formation of the catalyst in situ captures functional elements of the oxygen evolving complex of Photosystem II.

  5. Protective Agent-Free Synthesis of Colloidal Cobalt Nanoparticles

    SciTech Connect

    Balela, M. D. L.; Lockman, Z.; Azizan, A.; Matsubara, E.; Amorsolo, A. V. Jr.

    2010-03-11

    Spherical colloidal cobalt (Co) nanoparticles of about 2-7 nm were synthesized by hydrazine reduction in ethylene glycol at 80 deg. C. The mean diameter of the Co nanoparticles was varied to some extent by changing the pH, temperature, Co(II) chloride hexahydrate concentration, and amount of hydrazine. The Co particle size was reduced by decreasing Co(II) chloride concentration and increasing amount of hydrazine.

  6. Crystal structure of an unknown solvate of {2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato-κ(4) O,N,N',O'}(N-ferrocenylisonicotinamide-κN (1))cobalt(II): a Co(II)-salen complex that forms hydrogen-bonded dimers.

    PubMed

    Brautigam, Bryan; Herholdt, Chelsea; Farnsworth, William; Brudi, Ellen; McDonald, Eric; Wu, Guang; Contakes, Stephen

    2015-09-01

    The title compound, [CoFe(C5H5)(C16H14N2O2)(C11H9N2O)], was prepared as an air-stable red-brown solid by mixing equimolar amounts of {2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato}cobalt(II) and N-ferrocenylisonicotinamide in dry di-chloro-methane under nitro-gen and was characterized by ESI-MS, IR, and single-crystal X-ray diffraction. The structure at 100 K has triclinic (P-1) symmetry and indicates that the complex crystallizes as a mixture of λ and δ conformers. It exhibits the expected square pyramidal geometry about Co, and forms hydrogen-bonded dimers through amide N-H groups and phenolate O atoms on an adjacent mol-ecule. The involvement of only half of the salen ring structure in hydrogen-bonding inter-actions results in slight folding of the salen ring away from the pyridine coordination site in the δ conformer with an inter-salicyl-idene fold angle of 9.9 (7)°. In contrast, the λ conformer is nearly planar. The dimers pack into an open structure containing channels filled with highly disordered solvent mol-ecules. These solvent molecules' contributions to the intensity data were removed with the SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9-18] available in PLATON.

  7. Enhancement of trichothecene production in Fusarium graminearum by cobalt chloride.

    PubMed

    Tsuyuki, Rie; Yoshinari, Tomoya; Sakamoto, Naoko; Nagasawa, Hiromichi; Sakuda, Shohei

    2011-03-09

    The effects of cobalt chloride on the production of trichothecene and ergosterol in Fusarium graminearum were examined. Incorporation experiments with (13)C-labeled acetate and leucine confirmed that both 3-acetyldeoxynivalenol and ergosterol were biosynthesized via a mevalonate pathway by the fungus, although hydroxymethyl-glutaryl CoA (HMG-CoA) from intact leucine was able to be partially used for ergosterol production. Addition of cobalt chloride at concentrations of 3-30 μM into liquid culture strongly enhanced 3-acetyldeoxynivalenol production by the fungus, whereas the amount of ergosterol and the mycelial weight of the fungus did not change. The mRNA levels of genes encoding trichothecene biosynthetic proteins (TRI4 and TRI6), ergosterol biosynthetic enzymes (ERG3 and ERG25), and enzymes involved in the mevalonate pathway (HMG-CoA synthase (HMGS) and HMG-CoA reductase (HMGR)) were all strongly up-regulated in the presence of cobalt chloride. Precocene II, a specific trichothecene production inhibitor, suppressed the effects of cobalt chloride on Tri4, Tri6, HMGS, and HMGR, but did not affect erg3 and erg25. These results indicate that cobalt chloride is useful for investigating regulatory mechanisms of trichothecene and ergosterol production in F. graminearum.

  8. Use of indium-111 oxine to study pulmonary and hepatic leukocyte sequestration in endotoxin shock and effects of the beta-2 receptor agonist terbutaline

    SciTech Connect

    Sigurdsson, G.H.; Christenson, J.T.; al-Mousawi, M.; Owunwanne, A. )

    1989-01-01

    The dynamic behavior of indium-111 oxine-labeled leukocytes was simultaneously recorded in multiple organs during endotoxin shock in sheep. Also, the effects of the beta-2 receptor agonist terbutaline were studied. An experimental protocol was designed to mimic a clinical condition in an intensive care setting as far as possible. The animals were ventilated with 50% oxygen to avoid hypoxemia and were given large amounts of intravenous fluids to reduce adverse effects of hypovolemia. A moderate dose of E. coli endotoxin (10 micrograms/kg bwt) was given by intravenous infusion to 14 adult sheep, seven of them receiving continuous intravenous infusion of terbutaline (20 micrograms/kg/hr) during 4 hr, starting 30 min after endotoxin, when signs of lung injury had developed. The other seven acted as controls. A marked pulmonary and hepatic leukocyte sequestration together with a sharp drop in leukocyte counts in peripheral blood occurred within minutes after start of the endotoxin infusion in both groups. However, no changes were observed in the kidneys or the gut. After 60 min and until the end of the experiment, there was a significantly lower activity in the lungs and in the liver of the animals treated with terbutaline than in the controls (P less than .01). Furthermore, less marked hemodynamic and respiratory alterations occurred in the terbutaline group compared with the controls. This study confirms the results of other investigators showing that significant leukocyte sequestration occurs in the lungs during endotoxemia, but it also demonstrates that leukocytes sequestrate in the liver, although slightly less than in the lungs.

  9. Adapting Ruthenium Sensitizers to Cobalt Electrolyte Systems.

    PubMed

    Amit Kumar, Sangeeta; Urbani, Maxence; Medel, María; Ince, Mine; González-Rodríguez, David; Chandiran, Aravind Kumar; Bhaskarwar, Ashok N; Torres, Tomás; Nazeeruddin, Md K; Grätzel, Michael

    2014-02-06

    In this work, we report the use of bulky substitutions in a new heteroleptic ruthenium(II) bipyridine complex, Ru(NCS)2LL', coded TT-230 to obtain high open-circuit potential in a dye-sensitized solar cell (where L is a bipyridine ligand appended with two cyclopenta(2,1-b;3,4-bA)dithiophene moieties, and L' = 4,4,'-dicarboxylic acid 2,2'-bipyridine). The electrolytes based on cobalt complexes have shown significant advantages in terms of attainable open-circuit potential compared to the standard iodide/tri-iodide redox mediators. These merits of the cobalt complexes were previously realized with a porphyrin sensitizer, achieving a VOC greater than 1 V in DSC. However, with conventional Ru(II)-polypyridyl complexes such as the C101 dye, similar increase in the VOC could not be attained due to the enhanced recombination. In this work, we have shown that the use of bulky substituents can prevent the back reaction of photogenerated electron and subsequently increase the open-circuit potential of the device. The recombination processes were investigated by transient photovoltage decay measurements.

  10. Effects of cobalt chloride on nitric oxide and cytokines/chemokines production in microglia.

    PubMed

    Mou, Yan Hua; Yang, Jing Yu; Cui, Nan; Wang, Ji Ming; Hou, Yue; Song, Shuang; Wu, Chun Fu

    2012-05-01

    The involvement of microglial activation in metal neurotoxicity is becoming increasingly recognized. Some metal ions, such as zinc (II) and manganese (II), have been recently reported as microglial activators to induce the release of inflammatory mediators including cytokines, chemokines and nitric oxide (NO) which are involved in the pathogenesis of neurological diseases. Cobalt is essential for human life. However, excessive cobalt is cytotoxic and neurotoxic. In the present study, we determined cobalt-induced production of NO and cytokines/chemokines in N9 cells, a murine microglial cell line. High levels of cobalt significantly up-regulated iNOS mRNA and protein expression, which resulted in the release of NO. Cobalt induced the production of tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) in a concentration- and time-dependent manner in both N9 cells and primary mouse microglia and increased lipopolysaccharides (LPS)-induced cytokine production. Further study showed that cobalt induced cytokine production by a mechanism involving both nuclear factor kappa B (NF-κB) and p38 mitogen-activated protein kinase (MAPK) signaling pathways. The involvement of reactive oxygen species (ROS) in microglial activation was also confirmed. These findings suggested that cobalt neurotoxicity should be attributed not only directly to neuronal damage but also indirectly to microglial activation which might potentiate neuronal injury via elevation of proinflammatory mediator levels.

  11. Cobalt: for strength and color

    USGS Publications Warehouse

    Boland, Maeve A.; Kropschot, S.J.

    2011-01-01

    Cobalt is a shiny, gray, brittle metal that is best known for creating an intense blue color in glass and paints. It is frequently used in the manufacture of rechargeable batteries and to create alloys that maintain their strength at high temperatures. It is also one of the essential trace elements (or "micronutrients") that humans and many other living creatures require for good health. Cobalt is an important component in many aerospace, defense, and medical applications and is a key element in many clean energy technologies. The name cobalt comes from the German word kobold, meaning goblin. It was given this name by medieval miners who believed that troublesome goblins replaced the valuable metals in their ore with a substance that emitted poisonous fumes when smelted. The Swedish chemist Georg Brandt isolated metallic cobalt-the first new metal to be discovered since ancient times-in about 1735 and identified some of its valuable properties.

  12. Cobalt(I), -(II), and -(III) complexes of a tetraaza 14-membered macrocycle, 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene (L). Crystal and molecular structures of (CoL(CO))ClO sub 4 , trans-CoLCl sub 2 , and cis-(CoL(CO sub 3 ))ClO sub 4

    SciTech Connect

    Szalda, D.J.; Fujita, E.; Creutz, C. )

    1989-04-19

    The carbon monoxide adduct of the cobalt(I) title macrocycle has been prepared via reaction of CoL{sup +} with CO{sub 2} and with CO and isolated as a perchlorate salt: IR (Nujol){nu}{sub CO} 1916 cm{sup {minus}1}; UV-vis (CH{sub 3}CH, {lambda}{sub max} ({epsilon})) 310 nm (3900 M{sup {minus}1} cm{sup {minus}1}), 430 sh (770), 510 sh (360), 1040 (240). In CH{sub 3}CN solvent its stability constant is {approx} 3 {times} 10{sup 8} M{sup {minus}1} at 25{degree}C. Structures of the square-pyramidal carbonyl complex and two other complexes of the title macrocycle have been determined from single-crystal x-ray diffraction data collected with use of Mo K{alpha} radiation. Crystallographic data: (CoL(CO))(ClO{sub 4}) (1), C2, a = 15.362 (3) {angstrom}, b = 7.580 (5) {angstrom}, c = 9.611 (3) {angstrom}, {beta} = 108.91 (2){degree}, V = 1059 (1) {angstrom}{sup 3}, Z = 2 (R = 0.057, R{sub w} = 0.069); N-meso,trans-CoLCl{sub 2} (2), Pbca, a = 11.570 (3) {angstrom}, b = 12.695 (3) {angstrom}, c = 13.309 (2) {angstrom}, V = 1954 (1) {angstrom}{sup 3}, Z = 4 (R = 0.075, R{sub w} = 0.070); cis-(CoL(CO{sub 3}))ClO{sub 4} (3), C2, a = 15.072 (5) {angstrom}, b = 7.603 (4) {angstrom}, c = 9.703 (3) {angstrom}, {beta} = 109.74 (3){degree}, V = 1047 (1) {angstrom}{sup 3}, Z = 2 (R = 0.033, R{sub w} = 0.048). The three structures contain square-pyramidal, five-coordinate cobalt(I) (1), strongly axially distorted six-coordinate cobalt(II) (2), and six-coordinate cobalt(III) with L occupying cis-coordination positions (3). They thus provide a striking illustration of the adaptability of L to a variety of coordination numbers and oxidation states. 30 refs., 3 figs., 8 tabs.

  13. Molecular cobalt pentapyridine catalysts for generating hydrogen from water.

    PubMed

    Sun, Yujie; Bigi, Julian P; Piro, Nicholas A; Tang, Ming Lee; Long, Jeffrey R; Chang, Christopher J

    2011-06-22

    A set of robust molecular cobalt catalysts for the generation of hydrogen from water is reported. The cobalt complex supported by the parent pentadentate polypyridyl ligand PY5Me(2) features high stability and activity and 100% Faradaic efficiency for the electrocatalytic production of hydrogen from neutral water, with a turnover number reaching 5.5 × 10(4) mol of H(2) per mole of catalyst with no loss in activity over 60 h. Control experiments establish that simple Co(II) salts, the free PY5Me(2) ligand, and an isostructural PY5Me(2) complex containing redox-inactive Zn(II) are all ineffective for this reaction. Further experiments demonstrate that the overpotential for H(2) evolution can be tuned by systematic substitutions on the ancillary PY5Me(2) scaffold, presaging opportunities to further optimize this first-generation platform by molecular design.

  14. Concerning the deactivation of cobalt(III)-based porphyrin and salen catalysts in epoxide/CO2 copolymerization.

    PubMed

    Xia, Wei; Salmeia, Khalifah A; Vagin, Sergei I; Rieger, Bernhard

    2015-03-09

    Functioning as active catalysts for propylene oxide (PO) and carbon dioxide copolymerization, cobalt(III)-based salen and porphyrin complexes have drawn great attention owing to their readily modifiable nature and promising catalytic behavior, such as high selectivity for the copolymer formation and good regioselectivity with respect to the polymer microstructure. Both cobalt(III)-salen and porphyrin catalysts have been found to undergo reduction reactions to their corresponding catalytically inactive cobalt(II) species in the presence of propylene oxide, as evidenced by UV/Vis and NMR spectroscopies and X-ray crystallography (for cobalt(II)-salen). Further investigations on a TPPCoCl (TPP = tetraphenylporphyrin) and NaOMe system reveal that such a catalyst reduction is attributed to the presence of alkoxide anions. Kinetic studies of the redox reaction of TPPCoCl with NaOMe suggests a pseudo-first order in cobalt(III)-porphyrin. The addition of a co-catalyst, namely bis(triphenylphosphine)iminium chloride (PPNCl), into the reaction system of cobalt(III)-salen/porphyrin and PO shows no direct stabilizing effect. However, the results of PO/CO2 copolymerization by cobalt(III)-salen/porphyrin with PPNCl suggest a suppressed catalyst reduction. This phenomenon is explained by a rapid transformation of the alkoxide into the carbonate chain end in the course of the polymer formation, greatly shortening the lifetime of the autoreducible PO-ring-opening intermediates, cobalt(III)-salen/porphyrin alkoxides.

  15. Orientational disorder in the one-dimensional coordination polymer catena-poly[[bis­(acetyl­acetonato-κ2 O,O′)cobalt(II)]-μ-1,4-di­aza­bicyclo­[2.2.2]octane-κ2 N 1:N 4

    PubMed Central

    Dumitru, Florina; Englert, Ulli; Braun, Beatrice

    2016-01-01

    The title compound, [Co(C5H7O2)2(C6H12N2)]n, was obtained as a one-dimensional coordination polymer from bis­(acetyl­acetonato)di­aqua­cobalt(II), [Co(acac)2(OH2)2], and 1,4-di­aza­bicyclo­[2.2.2]octane (DABCO), a di­amine with good bridging ability and rod-like spacer function. In the chain complex that extends along the c axis, the CoII atom is six-coordinated, the O-donor atoms of the chelating acac ligands occupying the equatorial positions and the bridging DABCO ligands being in trans-axial positions. In the crystal structure, the DABCO ligand is conformationally disordered in a 50:50 manner as a result of its location across a crystallographic mirror plane. The metal–metal distance is very close to that in a related compound exhibiting weak anti­ferromagnetic exchange between the CoII ions, and the title compound can thus be useful for obtaining more information about the contribution of different bridges to the magnetic coupling between paramagnetic ions. PMID:27375886

  16. Nano-Web Cobalt Modified Silica Nanoparticles Catalysts for Water Oxidation and MB Oxidative Degradation.

    PubMed

    Wang, Li; Chen, Qiuyun; Li, Chenghao; Fang, Fang

    2016-05-01

    Dioxygen generating materials, using water as oxygen source, can be used as catalysts in hypoxic environments. Cobalt(II) modified silica (SiO2@NPCo) nanoparticles were synthesized through coordination of cobalt(II) ions with nitrogen atoms from 2-acetylpyridine modified silica (SiO2@NP). The SiO2@NPCo nanoparticles further reacted with 1,3,5-benzenetricarboxylic acids, forming porous nano-web nanoparticles (SiO2@NPCoCOOH). The synthesized SiO2@NPCoCOOH nanoparticles were demonstrated as better white LED light driven photochemical catalysts for oxidation of water than individual nanoparticles (SiO2@NPCo). Moreover, the SiO2@NPCoCOOH/water system could decrease the content of methylene blue (MB) in solution and therefore, the nanoweb cobalt(II) modified silica nanoparticles can be environmentally friendly catalysts for oxidative degradation of MB, using water as the oxygen source.

  17. Structure and optical properties of glasses in binary liquid crystalline systems based on cobalt octanoate

    NASA Astrophysics Data System (ADS)

    Mirnaya, T. A.; Tokmenko, I. I.; Yaremchuk, G. G.; Tolochko, A. S.

    2015-04-01

    The effect of composition and aggregative state (melt, mesophase, glass) on the coordination state of Co (II) ions in an octanoate ligand field has been studied for binary liquid crystalline systems based on cobalt (II) octanoate by the analysis of electronic absorption spectra. It has been shown that several coordination forms of Co (II) ions: octahedral, tetrahedral and dodecahedral ones can coexist in cobalt octanoate based systems. It has been found by positron annihilation lifetime spectroscopy and small-angle X-ray scattering that glasses of cobalt octanoate based systems have a bilayer and nanoporous structure. The thickness of cation-anion bilayers in mesophases and glasses of binary systems depends on the polarizing power of cations: it is the smaller, the higher the polarizing power of cations.

  18. Controlling the misuse of cobalt in horses.

    PubMed

    Ho, Emmie N M; Chan, George H M; Wan, Terence S M; Curl, Peter; Riggs, Christopher M; Hurley, Michael J; Sykes, David

    2015-01-01

    Cobalt is a well-established inducer of hypoxia-like responses, which can cause gene modulation at the hypoxia inducible factor pathway to induce erythropoietin transcription. Cobalt salts are orally active, inexpensive, and easily accessible. It is an attractive blood doping agent for enhancing aerobic performance. Indeed, recent intelligence and investigations have confirmed cobalt was being abused in equine sports. In this paper, population surveys of total cobalt in raceday samples were conducted using inductively coupled plasma mass spectrometry (ICP-MS). Urinary threshold of 75 ng/mL and plasma threshold of 2 ng/mL could be proposed for the control of cobalt misuse in raceday or in-competition samples. Results from administration trials with cobalt-containing supplements showed that common supplements could elevate urinary and plasma cobalt levels above the proposed thresholds within 24 h of administration. It would therefore be necessary to ban the use of cobalt-containing supplements on raceday as well as on the day before racing in order to implement and enforce the proposed thresholds. Since the abuse with huge quantities of cobalt salts can be done during training while the use of legitimate cobalt-containing supplements are also allowed, different urinary and plasma cobalt thresholds would be required to control cobalt abuse in non-raceday or out-of-competition samples. This could be achieved by setting the thresholds above the maximum urinary and plasma cobalt concentrations observed or anticipated from the normal use of legitimate cobalt-containing supplements. Urinary threshold of 2000 ng/mL and plasma threshold of 10 ng/mL were thus proposed for the control of cobalt abuse in non-raceday or out-of-competition samples.

  19. Following the Formation of Active Co(III) Sites in Cobalt Substituted Aluminophosphates Catalysts by In-Situ Combined UV-VIS/XAFS/XRD Technique

    SciTech Connect

    Sankar, Gopinathan; Fiddy, Steven; Harvey, Ian; Hayama, Shusaku; Bushnell-Wye, Graham; Beale, Andrew M.

    2007-02-02

    Cobalt substituted aluminophosphates, CoAlPO-34 (Chabazite structure) and DAF-8 (Phillipsite structure) were investigated by in situ combined XRD/EXAFS/UV-VIS technique. In-situ combined XRD, Co K-edge EXAFS and UV-Vis measurements carried out during the calcination process reveal that CoAlPO-34 containing 10 wt percent cobalt is stable and the cobalt ions are converted from Co(II) in the as synthesised form to Co(III); DAF-8 containing about 25 percent cobalt is not stable and does not show change in oxidation state.

  20. Preparation and characterization of copper-doped cobalt oxide electrodes.

    PubMed

    Rosa-Toro, A La; Berenguer, R; Quijada, C; Montilla, F; Morallón, E; Vazquez, J L

    2006-11-30

    Cobalt oxide (Co3O4) and copper-doped cobalt oxide (CuxCo(3-x)O4) films have been prepared onto titanium support by the thermal decomposition method. The electrodes have been characterized by different techniques such as cyclic voltammetry, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). The effect on the electrochemical and crystallographic properties and surface morphology of the amount of copper in the oxide layer has been analyzed. The XPS spectra correspond to a characteristic monophasic Cu-Co spinel oxides when x is below 1. However, when the copper content exceeds that for the stoichiometric CuCo2O4 spinel, a new CuO phase segregates at the surface. The analysis of the surface cation distribution indicates that Cu(II) has preference for octahedral sites.

  1. Electrodeposition of cobalt-chromium alloy from trivalent chromium solutions

    SciTech Connect

    Dasarathy, H.; Riley, C.; Coble, H.D. . Dept. of Chemistry and Materials Science)

    1994-07-01

    Cobalt-chromium alloy was deposited from plating solutions containing cobalt(II) chloride and chromium(III) chloride at 3.5 pH. The deposits were obtained using both single and mixed complex solutions. Deposit morphology showed significant dependence on the complexing agent(s) used. Partitioning of the two components in the deposit as determined by energy dispersive spectroscopy depended on plating parameters such as concentration ratio of the two salts in the solution, complexing agent, type of current (both dc and pulsed current were studied), and current density. X-ray photoelectron spectroscopy spectra collected from as-deposited alloy revealed the presence of both oxides and metals. X-ray diffraction spectra for the alloy deposit indicated solid solution formation.

  2. A triclinic polymorph of catena-poly[[bis-(N,N-dimethyl-formamide-κO)cobalt(II)]-di-μ-1,5-dicyanamido-κ(4)N(1):N(5)].

    PubMed

    Meng, S C

    2012-11-01

    The title compound, [Co(C(2)N(3))(2)(C(3)H(7)NO)(2)](n), is a triclinic polymorph of the previously reported monoclinic structure [Tong et al. (2003 ▶). Acta Cryst. E59, m405-m407]. The Co(II) ion lies on an inversion centre and adopts an almost regular octa-hedral N(4)O(2) coordination geometry. Adjacent Co(II) atoms are connected by two bridging dicyanamide ligands, resulting in the formation of neutral chains parallel to the b axis. The title complex is isotypic with the Mn(II) analogue but not with the Ni(II) analogue.

  3. Modification of Wide-Band-Gap Oxide Semiconductors with Cobalt Hydroxide Nanoclusters for Visible-Light Water Oxidation.

    PubMed

    Maeda, Kazuhiko; Ishimaki, Koki; Tokunaga, Yuki; Lu, Daling; Eguchi, Miharu

    2016-07-11

    Cobalt-based compounds, such as cobalt(II) hydroxide, are known to be good catalysts for water oxidation. Herein, we report that such cobalt species can also activate wide-band-gap semiconductors towards visible-light water oxidation. Rutile TiO2 powder, a well-known wide-band-gap semiconductor, was capable of harvesting visible light with wavelengths of up to 850 nm, and thus catalyzed water oxidation to produce molecular oxygen, when decorated with cobalt(II) hydroxide nanoclusters. To the best of our knowledge, this system constitutes the first example that a particulate photocatalytic material that is capable of water oxidation upon excitation by visible light can also operate at such long wavelengths, even when it is based on earth-abundant elements only.

  4. Electrosynthesis of highly transparent cobalt oxide water oxidation catalyst films from cobalt aminopolycarboxylate complexes.

    PubMed

    Bonke, Shannon A; Wiechen, Mathias; Hocking, Rosalie K; Fang, Xi-Ya; Lupton, David W; MacFarlane, Douglas R; Spiccia, Leone

    2015-04-24

    Efficient catalysis of water oxidation represents one of the major challenges en route to efficient sunlight-driven water splitting. Cobalt oxides (CoOx ) have been widely investigated as water oxidation catalysts, although the incorporation of these materials into photoelectrochemical devices has been hindered by a lack of transparency. Herein, the electrosynthesis of transparent CoOx catalyst films is described by utilizing cobalt(II) aminopolycarboxylate complexes as precursors to the oxide. These complexes allow control over the deposition rate and morphology to enable the production of thin, catalytic CoOx films on a conductive substrate, which can be exploited in integrated photoelectrochemical devices. Notably, under a bias of 1.0 V (vs. Ag/AgCl), the film deposited from [Co(NTA)(OH2 )2 ](-) (NTA=nitrilotriacetate) decreased the transmission by only 10 % at λ=500 nm, but still generated >80 % of the water oxidation current produced by a [Co(OH2 )6 ](2+) -derived oxide film whose transmission was only 40 % at λ=500 nm.

  5. Cosine (Cobalt Silicide Growth Through Nitrogen-Induced Epitaxy) Process For Epitaxial Cobalt Silicide Formation For High Performance Sha

    DOEpatents

    Lim, Chong Wee; Shin, Chan Soo; Gall, Daniel; Petrov, Ivan Georgiev; Greene, Joseph E.

    2004-09-28

    A method for forming an epitaxial cobalt silicide layer on a MOS device includes sputter depositing cobalt in an ambient to form a first layer of cobalt suicide on a gate and source/drain regions of the MOS device. Subsequently, cobalt is sputter deposited again in an ambient of argon to increase the thickness of the cobalt silicide layer to a second thickness.

  6. Cobalt and antimony: genotoxicity and carcinogenicity.

    PubMed

    De Boeck, Marlies; Kirsch-Volders, Micheline; Lison, Dominique

    2003-12-10

    The purpose of this review is to summarise the data concerning genotoxicity and carcinogenicity of Co and Sb. Both metals have multiple industrial and/or therapeutical applications, depending on the considered species. Cobalt is used for the production of alloys and hard metal (cemented carbide), diamond polishing, drying agents, pigments and catalysts. Occupational exposure to cobalt may result in adverse health effects in different organs or tissues. Antimony trioxide is primarily used as a flame retardant in rubber, plastics, pigments, adhesives, textiles, and paper. Antimony potassium tartrate has been used worldwide as an anti-shistosomal drug. Pentavalent antimony compounds have been used for the treatment of leishmaniasis. Co(II) ions are genotoxic in vitro and in vivo, and carcinogenic in rodents. Co metal is genotoxic in vitro. Hard metal dust, of which occupational exposure is linked to an increased lung cancer risk, is proven to be genotoxic in vitro and in vivo. Possibly, production of active oxygen species and/or DNA repair inhibition are mechanisms involved. Given the recently provided proof for in vitro and in vivo genotoxic potential of hard metal dust, the mechanistic evidence of elevated production of active oxygen species and the epidemiological data on increased cancer risk, it may be advisable to consider the possibility of a new evaluation by IARC. Both trivalent and pentavalent antimony compounds are generally negative in non-mammalian genotoxicity tests, while mammalian test systems usually give positive results for Sb(III) and negative results for Sb(V) compounds. Assessment of the in vivo potential of Sb2O3 to induce chromosome aberrations (CA) gave conflicting results. Animal carcinogenicity data were concluded sufficient for Sb2O3 by IARC. Human carcinogenicity data is difficult to evaluate given the frequent co-exposure to arsenic. Possible mechanisms of action, including potential to produce active oxygen species and to interfere with

  7. Polytypic transformations during the thermal decomposition of cobalt hydroxide and cobalt hydroxynitrate

    SciTech Connect

    Ramesh, Thimmasandra Narayan

    2010-06-15

    The isothermal decomposition of cobalt hydroxide and cobalt hydroxynitrate at different intervals of temperature leads to the formation of Co{sub 3}O{sub 4}. The phase evolution during the decomposition process was monitored using powder X-ray diffraction. The transformation of cobalt hydroxide to cobalt oxide occurs via three phase mixture while cobalt hydroxynitrate to cobalt oxide occurs through a two phase mixture. The nature of the sample and its preparation method controls the decomposition mechanism. The comparison of topotactical relationship between the precursors to the decomposed product has been reported in relation to polytypism. - Graphical abstract: Isothermal thermal decomposition studies of cobalt hydroxide and cobalt hydroxynitrate at different intervals of temperature show the metastable phase formed prior to Co{sub 3}O{sub 4} phase.

  8. On the cobalt and cobalt oxide electrodeposition from a glyceline deep eutectic solvent.

    PubMed

    Sakita, Alan M P; Della Noce, Rodrigo; Fugivara, Cecílio S; Benedetti, Assis V

    2016-09-14

    The electrodeposition of cobalt and cobalt oxides from a glyceline deep eutectic solvent is reported. Cyclic voltammetry, chronoamperometry, scanning electron microscopy, and Raman spectroscopy are employed to study the Co deposition processes. Surface analysis reveals that metallic cobalt is deposited at potentials less negative than the current peak potential whereas cobalt oxides are detected and electrochemically observed when the deposition is done at more negative potentials. i-t transients are analyzed by applying the Scharifker and Hills (SH) theoretical model. It is concluded that cobalt deposition occurs via a progressive nucleation and growth mechanism for concentrations higher than 0.05 mol L(-1) cobalt ions. For concentrations ≤0.025 mol L(-1) cobalt ions and low overpotentials, the mechanism changes to instantaneous nucleation. The im-tm relationships of the SH model are used to determine the values of the kinetic parameters and the cobalt ion diffusion coefficient.

  9. Electrochemical Detection of Transient Cobalt Hydride Intermediates of Electrocatalytic Hydrogen Production.

    PubMed

    Wiedner, Eric S; Bullock, R Morris

    2016-07-06

    A large variety of molecular cobalt complexes are used as electrocatalysts for H2 production, but the key cobalt hydride intermediates are frequently difficult to detect and characterize due to their high reactivity. We report that a combination of variable scan rate cyclic voltammetry and foot-of-the-wave analysis (FOWA) can be used to detect transient Co(III)H and Co(II)H intermediates of electrocatalytic H2 production by [Co(II)(P(tBu)2N(Ph)2)(CH3CN)3](2+) and Co(II)(dmgBF2)2(CH3CN)2. In both cases, reduction of a transient catalytic intermediate occurs at a potential that coincides with the Co(II/I) couple. Each reduction displays quasireversible electron-transfer kinetics, consistent with reduction of a Co(III)H intermediate to Co(II)H, which is then protonated by acid to generate H2. A bridge-protonated Co(I) species was ruled out as a catalytic intermediate for Co(II)(dmgBF2)2(CH3CN)2 from voltammograms recorded at 1000 psi of H2. Density functional theory was used to calculate Co(III)-H and Co(II)-H bond strengths for both catalysts. Despite having very different ligands, the cobalt hydrides of both catalysts possess nearly identical heterolytic and homolytic Co-H bond strengths for the Co(III)H and Co(II)H intermediates.

  10. Cobalt-Base Alloy Gun Barrel Study

    DTIC Science & Technology

    2014-07-01

    Cobalt -Base Alloy Gun Barrel Study by William S. de Rosset and Jonathan S. Montgomery ARL-RP-0491 July 2014 A reprint...21005-5069 ARL-RP-0491 July 2014 Cobalt -Base Alloy Gun Barrel Study William S. de Rosset and Jonathan S. Montgomery Weapons and Materials...DATE (DD-MM-YYYY) July 2014 2. REPORT TYPE Reprint 3. DATES COVERED (From - To) October–November 2013 4. TITLE AND SUBTITLE Cobalt -Base Alloy

  11. Mineral resource of the month: cobalt

    USGS Publications Warehouse

    Shedd, Kim B.

    2009-01-01

    Cobalt is a metal used in numerous commercial, industrial and military applications. On a global basis, the leading use of cobalt is in rechargeable lithium-ion, nickel-cadmium and nickel-metal hydride battery electrodes. Cobalt use has grown rapidly since the early 1990s, with the development of new battery technologies and an increase in demand for portable electronics such as cell phones, laptop computers and cordless power tools.

  12. [Neurotoxic effects of cobalt: an open question].

    PubMed

    Catalani, S; Apostoli, P

    2011-01-01

    Increased cobalt levels have been associated with neurological diseases (hand tremor, incoordination, cognitive decline, depression, vertigo, hearing loss and visual changes) in addition to "classic" and known cardiac diseases (arrhythmias and cardiomyopathies) and allergic or endocrine symptoms. Cobalt neurotoxicity is reported in isolated cases: old occupational or iatrogenic exposures and more recent releases of metallic ions by prosthesis. The studies of these cases have revealed a typical symptomatology of cobalt probably due to its ability to induce oxidative stress and mitochondrial alterations.

  13. Cobalt-catalyzed C-H borylation.

    PubMed

    Obligacion, Jennifer V; Semproni, Scott P; Chirik, Paul J

    2014-03-19

    A family of pincer-ligated cobalt complexes has been synthesized and are active for the catalytic C-H borylation of heterocycles and arenes. The cobalt catalysts operate with high activity and under mild conditions and do not require excess borane reagents. Up to 5000 turnovers for methyl furan-2-carboxylate have been observed at ambient temperature with 0.02 mol % catalyst loadings. A catalytic cycle that relies on a cobalt(I)-(III) redox couple is proposed.

  14. Cobalt Distribution and Speciation: Effect of Aging, Intermittent Submergence, In situ Rice Roots

    EPA Science Inventory

    The speciation and distribution of cobalt (Co) in soils is poorly understood. This study was conducted using X-ray absorption spectroscopy (XAS) techniques to examine the influence of soluble Co(II) aging, submergence-dried cycling, and the presence of in vivo rice roots on the...

  15. Improvements upon the "Colorful Cobalt Catalysis" Demonstration and Evidence for the Presence of an Autocatalytic Mechanism

    ERIC Educational Resources Information Center

    Wright, Stephen W.

    2010-01-01

    The oxidation of potassium sodium tartrate by hydrogen peroxide catalyzed by cobalt(II) chloride is a favorite lecture demonstration. I present conditions under which this experiment may be performed without need for 30% hydrogen peroxide and without need for controlled heating or any heating of the reaction mixture. I further show that this…

  16. Solution for Depositing an Electroless Cobalt Alloy.

    DTIC Science & Technology

    SOLUTIONS(MIXTURES), *ELECTROLESS PLATING), (*PATENTS, ELECTROLESS PLATING), (*COBALT ALLOYS, ELECTROLESS PLATING), ADDITIVES, SODIUM COMPOUNDS... TUNGSTATES , POTASSIUM COMPOUNDS, NICKEL COMPOUNDS, SULFATES, THIOUREA, MAGNETIC PROPERTIES

  17. Crystallization behaviour of hydroxide cobalt carbonates by aging: Environmental implications.

    NASA Astrophysics Data System (ADS)

    González-López, Jorge; Fernández-González, Angeles; Jimenez, Amalia

    2014-05-01

    Cobalt is a naturally occurring element widely distributed in water, sediments and air that is essential for living species, since it is a component of B12 vitamin and it is also a strategic and critical element used in a number of commercial, industrial and military applications. However, relatively high accumulations of cobalt in environment can be toxic for human and animal health. Cobalt usually occurs as Co2+ and Co3+ in aqueous solutions, where Co2+ is the most soluble and hence its mobility in water is higher. The study of the precipitation of cobalt carbonates is of great interest due to the abundance of carbonate minerals in contact with surface water and groundwater which can be polluted with Co2+. Previous works have demonstrated that the formation of Co-bearing calcium carbonates and Co-rich low crystallinity phases takes place at ambient conditions. With the aim of investigating the crystallization behavior of Co- bearing carbonates at ambient temperature, macroscopic batch-type experiments have been carried out by mixing aqueous solutions of CoCl2 (0.05M) and Na2CO3 (0.05M) during increasing reaction times (5 minutes and 1, 5, 24, 48, 96, 168, 720 and 1440 hours). The main goals of this work were (i) to analyse the physicochemical evolution of the system and (ii) to study the evolution of the crystallinity of the solid phases during aging. After a given reaction period, pH, alkalinity and dissolved Co2+ in the aqueous solutions were analysed. The evolution of the morphology and chemical composition of the solids with aging time was examined by SEM and TEM. The precipitates were also analyzed by X-ray powder diffraction (XRD) and the crystallinity degree was followed by the intensity and the full width at high medium (FWHM) of the main peaks. The results show that a low crystallinity phase was obtained at the very beginning of aging. This phase evolves progressively to form hydroxide carbonate cobalt (Co2CO3(OH)2) which crystallize with the spatial

  18. Oxidation of low cobalt alloys

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.

    1982-01-01

    Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

  19. Cobalt-induced changes in the spleen of mice from different stages of development.

    PubMed

    Gluhcheva, Yordanka; Atanasov, Vasil; Ivanova, Juliana; Mitewa, Mariana

    2012-01-01

    Cobalt(II) accumulates in organs such as spleen, kidneys, heart, and liver. The aim of the present study was to investigate the effects of cobalt ethylenediamine tetraacetic acid (Co-EDTA) on spleen of developing mice. Pregnant BALB/c mice in late gestation were subjected to Co-EDTA treatment at daily doses of 75 or 125 mg/kg in drinking water, which continued until d 90 of the newborn pups. The newborn pups were sacrificed on d 18, 25, 30, 45, 60, and 90, which correspond to different stages of development. Spleens were excised, weighed, and processed for histological analysis. Spleen index (SI) was calculated as a ratio of spleen weight to body weight. Cobalt(II) bioaccumulation in spleen was determined using flame atomic absorption spectrometry (FAAS). Preliminary results showed that chronic treatment of mice with low- or high-dose Co-EDTA disturbed extramedullary hematopoiesis in the spleen. The number of megakaryocytes was reduced compared to controls. SI was also reduced in d 18 mice treated with low- or high-dose Co-EDTA. However, exposure to 75 mg/kg led to an increase of SI in all other experimental groups. FAAS analysis revealed significant cobalt(II) accumulation in spleen of treated mice. The Co(II) levels in spleens of d 18 mice were highest compared to other experimental groups, indicating that at this period mice are more sensitive to treatment. Exposure to cobalt-EDTA resulted in accumulation of Co(II) in spleen, altered SI, and hematopoiesis. Immature mice appear to be more sensitive to chronic treatment than adults.

  20. Chemical and electronic characterization of cobalt in a lanthanum perovskite. Effects of strontium substitution

    SciTech Connect

    Hueso, Jose L.; Holgado, Juan P.; Pereniguez, Rosa; Mun, Simon; Salmeron, Miquel; Caballero, Alfonso

    2010-01-15

    Two different cobaltites, LaCoO{sub 3} and La{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}}, have been prepared and characterized by means of high energy Co K-edge and low energy O K-edge X-ray absorption spectroscopy (XAS). Even though half of the La(III) is substituted by Sr(II), little or no changes can be detected in the formal oxidation state of cobalt atoms. The presence of strontium cations induces two main effects in the chemical and electronic state of the perovskite. The charge balance with Sr(II) species is reached by the formation of oxygen vacancies throughout the network, which explains the well-known increase in the reactivity of this substituted perovskite. O K-edge XAS experiments show that the Sr(II) species induce the transitions of d electrons of cobalt cations from low to high spin configuration. We propose that this change in spin multiplicity is induced by two cooperative effects: the oxygen vacancies, creating five coordinated cobalt atoms, and the bigger size of Sr(II) cations, aligning the Co-O-Co atoms, and favoring the overlapping of pi-symmetry cobalt and oxygen orbitals, reducing the splitting energy of e{sub g} and t{sub 2g} levels. - Graphical abstract: Change in spin multiplicity induced by the bigger size of Sr(II) cations, aligning the Co-O-Co atoms, and favoring the overlapping of pi-symmetry cobalt and oxygen orbitals.

  1. Synthesis, characterization, and reactivity of pentamethylcyclopentadienyl complexes of divalent cobalt and nickel

    SciTech Connect

    Smith, Michael Edward

    1993-10-01

    The thesis is divided into the following 4 chapters: synthesis, characterization, and reactivity of trinuclear pentamethylcyclopentadienyl cobalt and nickel clusters with triply-bridging methylidyne groups; chemical and physical properties of pentamethylcyclopentadienyl acetylacetonate complexes of Co(II) and Ni(II); synthesis, characterization, and reactivity of pentamethylcyclopentadienyl halide complexes of Co and Ni; and crystallographic studies of distortions in metallocenes with C5-symmetrical cyclopentadienyl rings.

  2. Late First-Row Transition-Metal Complexes Containing a 2-Pyridylmethyl Pendant-Armed 15-Membered Macrocyclic Ligand. Field-Induced Slow Magnetic Relaxation in a Seven-Coordinate Cobalt(II) Compound.

    PubMed

    Antal, Peter; Drahoš, Bohuslav; Herchel, Radovan; Trávníček, Zdeněk

    2016-06-20

    The 2-pyridylmethyl N-pendant-armed heptadentate macrocyclic ligand {3,12-bis(2-methylpyridine)-3,12,18-triaza-6,9-dioxabicyclo[12.3.1]octadeca-1,14,16-triene = L} and [M(L)](ClO4)2 complexes, where M = Mn(II) (1), Fe(II) (2), Co(II) (3), Ni(II) (4), and Cu(II) (5), were prepared and thoroughly characterized, including elucidation of X-ray structures of all the compounds studied. The complexes 1-5 crystallize in non-centrosymmetric Sohncke space groups as racemic compounds. The coordination numbers of 7, 6 + 1, and 5 were found in complexes 1-3, 4, and 5, respectively, with a distorted pentagonal bipyramidal (1-4) or square pyramidal (5) geometry. On the basis of the magnetic susceptibility experiments, a large axial zero-field splitting (ZFS) was found for 2, 3, and 4 (D(Fe) = -7.4(2) cm(-1), D(Co) = 34(1) cm(-1), and D(Ni) = -12.8(1) cm(-1), respectively) together with a rhombic ZFS (E/D = 0.136(3)) for 4. Despite the easy plane anisotropy (D > 0, E/D = 0) in 3, the slow relaxation of the magnetization below 8 K was observed and analyzed either with Orbach relaxation mechanism (the relaxation time τ0 = 9.90 × 10(-10) s and spin reversal barrier Ueff = 24.3 K (16.9 cm(-1))) or with Raman relaxation mechanism (C = 2.12 × 10(-5) and n = 2.84). Therefore, compound 3 enlarges the small family of field-induced single-molecule magnets with pentagonal-bipyramidal chromophore. The cyclic voltammetry in acetonitrile revealed reversible redox processes in 1-3 and 5, except for the Ni(II) complex 4, where a quasi-reversible process was dominantly observed. Presence of the two 2-pyridylmethyl pendant arms in L with a stronger σ-donor/π-acceptor ability had a great impact on the properties of all the complexes (1-5), concretely: (i) strong pyridine-metal bonds provided slight axial compression of the coordination sphere, (ii) substantial changes in magnetic anisotropy, and (iii) stabilization of lower oxidation states.

  3. Inhalation cancer risk assessment of cobalt metal.

    PubMed

    Suh, Mina; Thompson, Chad M; Brorby, Gregory P; Mittal, Liz; Proctor, Deborah M

    2016-08-01

    Cobalt compounds (metal, salts, hard metals, oxides, and alloys) are used widely in various industrial, medical and military applications. Chronic inhalation exposure to cobalt metal and cobalt sulfate has caused lung cancer in rats and mice, as well as systemic tumors in rats. Cobalt compounds are listed as probable or possible human carcinogens by some agencies, and there is a need for quantitative cancer toxicity criteria. The U.S. Environmental Protection Agency has derived a provisional inhalation unit risk (IUR) of 0.009 per μg/m(3) based on a chronic inhalation study of soluble cobalt sulfate heptahydrate; however, a recent 2-year cancer bioassay affords the opportunity to derive IURs specifically for cobalt metal. The mechanistic data support that the carcinogenic mode of action (MOA) is likely to involve oxidative stress, and thus, non-linear/threshold mechanisms. However, the lack of a detailed MOA and use of high, toxic exposure concentrations in the bioassay (≥1.25 mg/m(3)) preclude derivation of a reference concentration (RfC) protective of cancer. Several analyses resulted in an IUR of 0.003 per μg/m(3) for cobalt metal, which is ∼3-fold less potent than the provisional IUR. Future research should focus on establishing the exposure-response for key precursor events to improve cobalt metal risk assessment.

  4. Cobalt Reduction Guidelines, Revision 1. Final report

    SciTech Connect

    Not Available

    1993-12-01

    This report, which updates and supersedes an earlier report (EPRI NP-6737) on the same subject, describes methods for establishing a program to identify nuclear power plant valves with high-cobalt hardfacing that are potential significant contributors to the cobalt inventory that is irradiated in the reactor core. The resulting radioactive cobalt isotope, cobalt-60, is a major contributor to plant radiation levels and therefore occupational doses received by plant operational and maintenance personnel. A methodology to determine whether hardfacing is actually required on specific valves is also described as is the physical, mechanical and wear properties of high-cobalt and potential replacement cobalt-free hardfacing and trim alloys. Discussions are presented of the general and specific design requirements for valve hardfacing in nuclear service. Current world-wide nuclear utility experience with cobalt-free hardfacing alloys is described. The regulatory and industry code issues related to replacing and/or changing valve hardfacing materials are discussed. The actions and responsibilities of utility management in implementing an effective cobalt-reduction program are also delineated.

  5. Serum cobalt in children with essential hypertension.

    PubMed

    Nicoloff, G; Angelova, M; Christova, I; Nikolov, A; Alexiev, A

    2006-01-01

    The effect of cobalt on the cardiovascular system is one of many aspects of cobalt metabolism in humans. Elastin and collagen are the main proteins of the vascular wall. The aims of this study were: 1) to determine serum cobalt concentrations in children with hypertension; and 2) to study the correlation between serum cobalt and some biological markers of the extracellular matrix of the vascular wall, i.e., anti-elastin and anti-collagen type IV antibodies. Patients showed statistically significant higher levels of systolic and diastolic blood pressure, and significantly lower serum cobalt concentrations, than controls. Children with hypertension showed significantly higher levels of total cholesterol (P = 0.0003) and collagen type IV IgM (P = 0.04). Collagen type IV IgG levels (P = 0.027) were lower than in controls. Serum cobalt in patients showed a correlation with systolic blood pressure (r = -0.44, P = 0.05), elastin IgM (r = 0.60, P = 0.007), and collagen type IV IgG (r = -0.46, P = 0.04). Our data suggest the existence of a correlation between changes in levels of serum cobalt, total cholesterol, anti-collagen type IV antibodies, and essential hypertension in children. This is the first study of serum cobalt in children with essential hypertension.

  6. Cobalt Derivatives as Promising Therapeutic Agents

    PubMed Central

    Heffern, Marie C.; Yamamoto, Natsuho; Holbrook, Robert J.; Eckermann, Amanda L.; Meade, Thomas J.

    2013-01-01

    Inorganic complexes are versatile platforms for the development of potent and selective pharmaceutical agents. Cobalt possesses a diverse array of properties that can be manipulated to yield promising drug candidates. Investigations into the mechanism of cobalt therapeutic agents can provide valuable insight into the physicochemical properties that can be harnessed for drug development. This review presents examples of bioactive cobalt complexes with special attention to their mechanisms of action. Specifically, cobalt complexes that elicit biological effects through protein inhibition, modification of drug activity, and bioreductive activation are discussed. Insights gained from these examples reveal features of cobalt that can be rationally tuned to produce therapeutics with high specificity and improved efficacy for the biomolecule or pathway of interest. PMID:23270779

  7. Molecular electrocatalysis for oxygen reduction by cobalt porphyrins adsorbed at liquid/liquid interfaces.

    PubMed

    Su, Bin; Hatay, Imren; Trojánek, Antonín; Samec, Zdenek; Khoury, Tony; Gros, Claude P; Barbe, Jean-Michel; Daina, Antoine; Carrupt, Pierre-Alain; Girault, Hubert H

    2010-03-03

    Molecular electrocatalysis for oxygen reduction at a polarized water/1,2-dichloroethane (DCE) interface was studied, involving aqueous protons, ferrocene (Fc) in DCE and amphiphilic cobalt porphyrin catalysts adsorbed at the interface. The catalyst, (2,8,13,17-tetraethyl-3,7,12,18-tetramethyl-5-p-amino-phenylporphyrin) cobalt(II) (CoAP), functions like conventional cobalt porphyrins, activating O(2) via coordination by the formation of a superoxide structure. Furthermore, due to the hydrophilic nature of the aminophenyl group, CoAP has a strong affinity for the water/DCE interface as evidenced by lipophilicity mapping calculations and surface tension measurements, facilitating the protonation of the CoAP-O(2) complex and its reduction by ferrocene. The reaction is electrocatalytic as its rate depends on the applied Galvani potential difference between the two phases.

  8. Crystal structure of bis­(3,5-di­methyl­pyridine-κN)bis­(methanol-κO)bis­(thio­cyanato-κN)cobalt(II)

    PubMed Central

    Suckert, Stefan; Jess, Inke; Näther, Christian

    2016-01-01

    The asymmetric unit of the title complex, [Co(NCS)2(C7H9N)2(CH3OH)2], comprises of one CoII cation located on a centre of inversion, one thio­cyanate ligand, one methanol ligand and one 3,5-di­methyl­pyridine ligand. The CoII cation is octa­hedrally coordinated by two terminal N-bonding thio­cyanate anions, two methanol mol­ecules and two 3,5-di­methyl­pyridine ligands into a discrete complex. The complex mol­ecules are linked by inter­molecular O—H⋯S hydrogen bonding into chains that elongate in the direction parallel to the b axis. PMID:27980840

  9. Exposure to cobalt in the production of cobalt and cobalt compounds and its effect on the heart

    PubMed Central

    Linna, A; Oksa, P; Groundstroem, K; Halkosaari, M; Palmroos, P; Huikko, S; Uitti, J

    2004-01-01

    Aims: To investigate whether exposure to cobalt in cobalt plants has any measurable effect on the cardiovascular system. Methods: Occupational, cross sectional study, using a self administered questionnaire, blood pressure measurement, electrocardiography, and laboratory tests in which 203 male workers with at least one year of exposure to cobalt and 94 unexposed controls participated. Echocardiography was performed on a subset of 122 most highly exposed cobalt workers, of which 109 were analysed, and on 60 controls, of which 57 were analysed. Analysis of covariance and a multiple regression analysis were used to evaluate the data. Results: Two of the echocardiography parameters measured were associated with cobalt exposure. In the higher exposure group the left ventricular isovolumic relaxation time (mean 53.3, 49.1, and 49.7 ms in the high exposure, low exposure, and control groups respectively) and the deceleration time of the velocity of the early rapid filling wave (mean 194.3, 180.5, and 171.7 ms for those in the high exposure, low exposure, and control groups respectively) were prolonged, indicating altered left ventricular relaxation and early filling. Conclusion: Cumulative exposure to cobalt was found to be associated with the results of Doppler echocardiography measurements, indicating altered diastole. This finding supports the hypothesis that cobalt accumulation in the myocardium could affect myocardial function. Whether this finding has clinical implications remains to be evaluated. PMID:15477280

  10. Detection of boron, cobalt, and other weak interstellar lines toward Zeta Ophiuchi

    NASA Technical Reports Server (NTRS)

    Federman, S. R.; Sheffer, Y.; Lambert, D. L.; Gilliland, R. L.

    1993-01-01

    Numerous weak lines from interstellar atomic species toward Zeta Ophiuchi were observed with the Goddard High-Resolution Spectrograph. Of particular note are the first interstellar detection of cobalt and the detection of boron in this sight line. These measurements provide estimates for the amount of depletion for the two elements. Boron, a volatile, and cobalt, a refractory element, display the depletion pattern found by Savage et al. (1992). The abundance of phosphorus in the H II region associated with the star was obtained from a detection of P III. Additional weak lines from S I, C I, Ni II, and Cu II were detected for the first time; these lines provide the basis for refinements in oscillator strength and column density. Analysis of the neutral sulfur data indicates that the atomic gas is more widely distributed than the molecular material in the main component.

  11. Dipotassium tetra­aqua­bis­[3,5-bis­(dicyano­methyl­ene)cyclo­pentane-1,2,4-trionato(1−)-κN]cobaltate(II)

    PubMed Central

    Chagas, Luciano Honorato; Janczak, Jan; Machado, Flavia C.; de Oliveira, Luiz Fernando C.; Diniz, Renata

    2010-01-01

    The title structure, K2[Co(C11N4O3)2(H2O)4], is isotypic with K2[Fe(C11N4O3)2(H2O)4]. The CoII atom is in a distorted octa­hedral CoN2O4 geometry, forming a dianionic mononuclear entity. Each dianionic unit is associated with two potassium cations and inter­acts with adjacent units through O—H⋯N and O—H⋯O hydrogen bonds. PMID:21589332

  12. Advances in cobalt complexes as anticancer agents.

    PubMed

    Munteanu, Catherine R; Suntharalingam, Kogularamanan

    2015-08-21

    The evolution of resistance to traditional platinum-based anticancer drugs has compelled researchers to investigate the cytostatic properties of alternative transition metal-based compounds. The anticancer potential of cobalt complexes has been extensively studied over the last three decades, and much time has been devoted to understanding their mechanisms of action. This perspective catalogues the development of antiproliferative cobalt complexes, and provides an in depth analysis of their mode of action. Early studies on simple cobalt coordination complexes, Schiff base complexes, and cobalt-carbonyl clusters will be documented. The physiologically relevant redox properties of cobalt will be highlighted and the role this plays in the preparation of hypoxia selective prodrugs and imaging agents will be discussed. The use of cobalt-containing cobalamin as a cancer specific delivery agent for cytotoxins will also be described. The work summarised in this perspective shows that the biochemical and biophysical properties of cobalt-containing compounds can be fine-tuned to produce new generations of anticancer agents with clinically relevant efficacies.

  13. Crystal structure of catena-poly[bis­(tetra­ethyl­ammonium) [tetra­aqua­tris(μ-dicyanamido-κ2 N 1:N 5)bis(dicyanamido-κN 1)di­cobaltate(II)] dicyanamide

    PubMed Central

    Liu, Chen; Thuijs, Annaliese E.; Abboud, Khalil A.

    2016-01-01

    The structure of the title compound, [N(C2H5)4]2[Co2(C2N3)5(H2O)4](C2N3), is a new example of a metal–dicyanamide coordination polymer which exhibits a unique three-dimensional framework of covalently linked CoII chains. All bridging dicyanamide ligands in the title structure are in the μ 1,5-bridging mode. The anionic CoII-dicyanamide network is templated by tetra­ethyl­ammonium cations residing in a series of channels extending along the b axis where additional non-coordinating dicyanamidate anions are also located. The framework structure is further stabilized by O—H⋯N hydrogen bonding between aqua ligands and dicyanamido ligands or the dicyanamide anion. In addition, C—H⋯N inter­actions are present between the tetra­ethyl­ammonium cations and dicyanamide amide nitro­gen atoms. PMID:27840718

  14. Crystal structure, solvothermal synthesis, thermogravimetric studies and DFT calculations of a five-coordinate cobalt(II) compound based on the N,N-bis-(2-hy-droxy-eth-yl)glycine anion.

    PubMed

    Zhou, Yanling; Liu, Xianrong; Wang, Qijun; Wang, Lisheng; Song, Baoling

    2016-10-01

    The reaction of CoCl2·6H2O, N,N-bis-(2-hy-droxy-eth-yl)glycine and tri-ethyl-amine (Et3N) in ethanol solution under solvothermal conditions produced crystals of [N,N-bis-(2-hy-droxy-eth-yl)glycinato]chloridocobalt(II), [Co(C6H12NO4)Cl]. The Co(II) ion is coordinated in a slightly distorted trigonal-bipyramidal environment which is defined by three O atoms occupying the equatorial plane and the N and Cl atoms in the apical sites. In the crystal, two types of O-H⋯O hydrogen bonds connect the mol-ecules, forming a two-dimensional network parallel to (001). The mol-ecular structure of the title compound confirms the findings of FTIR, elemental analysis, ESI-MS analysis and TG analysis. By using the density functional theory (DFT) (B3LYP) method with 6-31G(d) basis set, the molecular structure has been calculated and optimized.

  15. Cobalt - poly(amido amine) superparamagnetic nanocomposites.

    PubMed

    Atwater, James E; Akse, James R; Holtsnider, John T

    2008-06-30

    Metallic cobalt-dendrimer nanocomposites were prepared using generation 5 Poly(amido amine) dendrimers with primary amino termini. Cobalt loading of ~38 atoms per dendrimer was determined by atomic absorption spectrophotometry. Magnetic properties of the cobalt-dendrimer nanocomposites were investigated across the temperature range from 2-300 K by SQUID magnetometry. Magnetization as a function of temperature and applied field strength was studied in zero field cooled samples. Magnetization-demagnetization curves (hysteresis loops) were also acquired at temperatures between 10 - 300 K. These results clearly indicate superparamagnetism for the nanocomposites with a characteristic blocking temperature of ~50 K.

  16. Cobalt - poly(amido amine) superparamagnetic nanocomposites

    PubMed Central

    Atwater, James E.; Akse, James R.; Holtsnider, John T.

    2010-01-01

    Metallic cobalt-dendrimer nanocomposites were prepared using generation 5 Poly(amido amine) dendrimers with primary amino termini. Cobalt loading of ~38 atoms per dendrimer was determined by atomic absorption spectrophotometry. Magnetic properties of the cobalt-dendrimer nanocomposites were investigated across the temperature range from 2–300 K by SQUID magnetometry. Magnetization as a function of temperature and applied field strength was studied in zero field cooled samples. Magnetization-demagnetization curves (hysteresis loops) were also acquired at temperatures between 10 – 300 K. These results clearly indicate superparamagnetism for the nanocomposites with a characteristic blocking temperature of ~50 K. PMID:20352068

  17. Crystal structure of an unknown solvate of {2,2′-[ethane-1,2-diylbis(nitrilo­methanylyl­idene)]diphenolato-κ4 O,N,N′,O′}(N-ferrocenylisonicotinamide-κN 1)cobalt(II): a CoII–salen complex that forms hydrogen-bonded dimers

    PubMed Central

    Brautigam, Bryan; Herholdt, Chelsea; Farnsworth, William; Brudi, Ellen; McDonald, Eric; Wu, Guang; Contakes, Stephen

    2015-01-01

    The title compound, [CoFe(C5H5)(C16H14N2O2)(C11H9N2O)], was prepared as an air-stable red–brown solid by mixing equimolar amounts of {2,2′-[ethane-1,2-diylbis(nitrilo­methanylyl­idene)]diphenolato}cobalt(II) and N-ferrocenylisonicotinamide in dry di­chloro­methane under nitro­gen and was characterized by ESI–MS, IR, and single-crystal X-ray diffraction. The structure at 100 K has triclinic (P-1) symmetry and indicates that the complex crystallizes as a mixture of λ and δ conformers. It exhibits the expected square pyramidal geometry about Co, and forms hydrogen-bonded dimers through amide N—H groups and phenolate O atoms on an adjacent mol­ecule. The involvement of only half of the salen ring structure in hydrogen-bonding inter­actions results in slight folding of the salen ring away from the pyridine coordination site in the δ conformer with an inter-salicyl­idene fold angle of 9.9 (7)°. In contrast, the λ conformer is nearly planar. The dimers pack into an open structure containing channels filled with highly disordered solvent mol­ecules. These solvent molecules’ contributions to the intensity data were removed with the SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9–18] available in PLATON. PMID:26396858

  18. Toxicology of wear particles of cobalt-chromium alloy metal-on-metal hip implants Part II: Importance of physicochemical properties and dose in animal and in vitro studies as a basis for risk assessment.

    PubMed

    Madl, Amy K; Kovochich, Michael; Liong, Monty; Finley, Brent L; Paustenbach, Dennis J; Oberdörster, Günter

    2015-07-01

    The objective of the Part II analysis was to evaluate animal and in vitro toxicology studies of CoCr particles with respect to their physicochemistry and dose relevance to metal-on-metal (MoM) implant patients as derived from Part I. In the various toxicology studies, physicochemical characteristics were infrequently considered and administered doses were orders of magnitude higher than what occurs in patients. Co was consistently shown to rapidly release from CoCr particles for distribution and elimination from the body. CoCr micron sized particles appear more biopersistent in vivo resulting in inflammatory responses that are not seen with similar mass concentrations of nanoparticles. We conclude, that in an attempt to obtain data for a complete risk assessment, future studies need to focus on physicochemical characteristics of nano and micron sized particles and on doses and dose metrics relevant to those generated in patients or in properly conducted hip simulator studies.

  19. Poly[1,4-bis­(4-pyridylmeth­yl)piperazine­diium [[tetra­aqua­cobaltate(II)]-μ-pyromellitato-κ2 O 1:O 4] dihydrate

    PubMed Central

    Sposato, Laura K.; LaDuca, Robert L.

    2009-01-01

    In the title compound, {(C16H22N4)[Co(C10H2O8)(H2O)4]·2H2O}n, the octa­hedrally coordinated CoII atom is situated on an inversion center and possesses four aqua ligands. The Co atoms are linked into an anionic coordination polymer chain by bis-monodentate pyromellitate ligands. The chain motifs are connected into a supra­molecular layer by hydrogen bonding mediated by uncoordinated water mol­ecules. Charge balance is provided by doubly protonated bis­(4-pyridylmeth­yl)piperazine units, which are anchored to the coordination polymer chain motifs by N—H⋯O hydrogen bonding. PMID:21578710

  20. (μ-4,4′-Bipyridine-κ2 N:N′)bis­[triaqua­(4,4′-bipyridine-κN)(3-nitro­phthalato-κO 2)cobalt(II)

    PubMed Central

    Guo, Hong-Xu; Yao, Zhong-Liang; Weng, Wen; Li, Xi-Zhong

    2009-01-01

    The title binuclear complex, [Co2(C8H3NO6)2(C10H8N2)3(H2O)6], has been synthesized hydro­thermally from 3-nitro­phthalic acid (H2NPA), Co(NO3)2·6H2O and 4,4′-bipyridine (4,4′-bipy). The mol­ecule of the complex occupies a special position on an inversion centre. The CoII atom has a slightly distorted octa­hedral environment formed by two N atoms from two 4,4′-bipy ligands, one carboxyl­ate O atom from NPA, and three O atoms of water mol­ecules. An extensive O—H⋯O and N—H⋯O hydrogen-bonding system links mol­ecules of the complex into a three-dimensional network. PMID:21583433

  1. Intra- and supra­molecular inter­actions in cis,mer-diaqua­tris­(1H-imidazole-κN 3)(terephthalato-κO)cobalt(II) monohydrate

    PubMed Central

    Benkanoun, Aouaouche; Balegroune, Fadila; Guehria-Laïdoudi, Achoura; Dahaoui, Slimane; Lecomte, Claude

    2012-01-01

    In the title compound, [Co(C8H4O4)(C3H4N2)3(H2O)2]·H2O, the cisoid angles are in the range 85.59 (5)–93.56 (5)°, while two equal transoid angles deviate significantly from the ideal linear angle, the third being almost linear. One carboxyl­ate group is almost coplanar [1.23 (13)°] with the plane of its parent aromatic ring, although it has one O-atom donor involved in one coordination and one hydrogen bond as acceptor. The other carboxyl­ate group does not coordinate and is rotated out of this plane with a torsional twist of 17.27 (20)°. The coordination neutral entity, based on aqua ligands and two cyclic co-ligands seems, at first sight, monomeric. Strongly tight, via one intra­molecular hydrogen bond between aqua and carboxyl­ate O atoms, it brings out a quasi-planar six-membered ring around the CoII atom, turning the CoN3O3 coordination octa­hedron into a new building block. The rigidity of this feature associated with several hydrogen-bonded arrays yields an extended structure. In the resulting supra­molecular packing, a binuclear hydrated CoII assembly, built up from triple strands driven by different heterosynthons, embodies the synergy of coordination, covalent and hydrogen bonds. PMID:22589841

  2. Synthesis, structural characterization, antibacterial activity and computational studies of new cobalt (II) complexes with 1,1,3,3-tetrakis (3,5-dimethyl-1-pyrazolyl)propane ligand

    NASA Astrophysics Data System (ADS)

    Beheshti, Azizolla; Safaeiyan, Forough; Hashemi, Faeze; Motamedi, Hossein; Mayer, Peter; Bruno, Giuseppe; Rudbari, Hadi Amiri

    2016-11-01

    Two new mono- and dinuclear Co(II) complexes namely [Co(tdmpp)Cl2]2·H2O (1) and [Co2(tdmpp)Cl4] (2) (where tdmpp = 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazolyl)propane) were prepared by one-pot reactions in methanol as a solvent. These compounds have been characterized by single crystal X-ray diffraction, elemental analysis, infrared spectroscopy, antibacterial activity and computational studies. In both complexes, Co (II) atom is tetrahedrally coordinated by two N atoms from one of the chelating bidentate bis(3,5-dimethylpyrazolyl)methane units of the tdmpp ligand and two Cl as terminal ligands. In these structures, the neighboring [Co(tdmpp)Cl2]2·H2O (1) and [Co2(tdmpp)Cl4] (2) molecules are joined together by the intermolecular Csbnd H⋯Cl hydrogen bonds to form a 1D chain structure. As a consequence of the intermolecular Csbnd H⋯π interactions these chains are further linked to generate a two-dimensional non-covalent bonded structure. The in vitro antibacterial activity studies of the free tdmpp ligand, compounds 1 and 2 show that the ability of these compounds to inhibit growth of the tested bacteria increase progressively from tdmpp to the dinuclear complex 2. Molecular-docking investigations between the five standard antibiotic, free tdmpp ligand, title complexes and five biological macromolecule enzymes (receptors) were carried out from using Autodock vina function. The results of docking studies confirmed that the metal complexes are more active than the free ligand. This is consistent with the results obtained by the antibacterial activities of these compounds.

  3. Cobalt-related defects in silicon

    NASA Astrophysics Data System (ADS)

    Gibbons, T. M.; Backlund, D. J.; Estreicher, S. K.

    2017-01-01

    Transition metals from the 3d series are unavoidable and unwanted contaminants in Si-based devices. Cobalt is one of the most poorly understood impurities with incomplete experimental information and few theoretical studies. In this contribution, the properties of interstitial cobalt (Coi) in Si and its interactions with the vacancy, self-interstitial, hydrogen, and substitutional boron are calculated using the first-principles tools. The stable configurations, gap levels, and binding energies are predicted. The activation energy for diffusing Coi is calculated with the nudged-elastic-band method and found to be slightly lower than that of interstitial copper and nickel. The binding energies and gap levels of the substitutional cobalt (Cos) and of the {Cos,H} and {Cos,H,H} complexes are close to the experimental data. The properties of the cobalt-boron pair are calculated.

  4. Bioextraction of cobalt from complex metal sulfides

    SciTech Connect

    Thompson, D.L.; Noah, K.S.; Wichlacz, P.L.; Torma, A.E.

    1993-05-01

    The present study has investigated the bioleachability of naturally occurring cobaltite and synthetic cobalt sulfides using 29 pedigree and ``wild type`` strains of Thiobacillus ferrooxidans. On the basis of a screening test, five strains of bacteria were selected for assessing the effects of leach parameters (pH, ferrous and ferric sulfates, ammonium sulfate, bipotassium hydrogen phosphate, and substrate concentrations) on cobalt extraction from Blackbird Mine ore and concentrate. The mechanisms of cobalt extraction were explained in terms of direct and indirect modes of bacterial activity, and the chemistry involved in these processes was identified. Using various size fractions of a high-grade cobaltite, the kinetic parameters of cobalt extraction were derived for the effect of specific surface area to be V{sub m} = 376 mg dm{sup {minus}3} h{sup {minus}1} and K 1.27 m{sup 2} g{sup {minus}1}.

  5. Bioextraction of cobalt from complex metal sulfides

    SciTech Connect

    Thompson, D.L.; Noah, K.S.; Wichlacz, P.L.; Torma, A.E.

    1993-01-01

    The present study has investigated the bioleachability of naturally occurring cobaltite and synthetic cobalt sulfides using 29 pedigree and wild type'' strains of Thiobacillus ferrooxidans. On the basis of a screening test, five strains of bacteria were selected for assessing the effects of leach parameters (pH, ferrous and ferric sulfates, ammonium sulfate, bipotassium hydrogen phosphate, and substrate concentrations) on cobalt extraction from Blackbird Mine ore and concentrate. The mechanisms of cobalt extraction were explained in terms of direct and indirect modes of bacterial activity, and the chemistry involved in these processes was identified. Using various size fractions of a high-grade cobaltite, the kinetic parameters of cobalt extraction were derived for the effect of specific surface area to be V[sub m] = 376 mg dm[sup [minus]3] h[sup [minus]1] and K 1.27 m[sup 2] g[sup [minus]1].

  6. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts....

  7. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts....

  8. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts....

  9. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts....

  10. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts....

  11. Role of cobalt in nickel base superalloys

    NASA Technical Reports Server (NTRS)

    Jarrett, R.; Barefoot, J.; Tien, J.; Sanchez, J.

    1982-01-01

    The effect of cobalt or substituting for cobalt on the mechanical properties of nickel-based superalloys is discussed. Waspaloy, UDIMET 700, and NIMONIC 115, which are representative of Ni-Cr-Co-Al-Ti-Mo superalloys having different gamma prime contents which are strengthened by a heavily alloyed matrix, coherent gamma prime precipitates, and carbides at the grain boundaries. Microstructure and in situ and extracted phase STEM micro-analysis were used to evaluate the three alloys.

  12. Ligand Engineering for the Efficient Dye-Sensitized Solar Cells with Ruthenium Sensitizers and Cobalt Electrolytes.

    PubMed

    Aghazada, Sadig; Gao, Peng; Yella, Aswani; Marotta, Gabriele; Moehl, Thomas; Teuscher, Joël; Moser, Jacques-E; De Angelis, Filippo; Grätzel, Michael; Nazeeruddin, Mohammad Khaja

    2016-07-05

    Over the past 20 years, ruthenium(II)-based dyes have played a pivotal role in turning dye-sensitized solar cells (DSCs) into a mature technology for the third generation of photovoltaics. However, the classic I3(-)/I(-) redox couple limits the performance and application of this technique. Simply replacing the iodine-based redox couple by new types like cobalt(3+/2+) complexes was not successful because of the poor compatibility between the ruthenium(II) sensitizer and the cobalt redox species. To address this problem and achieve higher power conversion efficiencies (PCEs), we introduce here six new cyclometalated ruthenium(II)-based dyes developed through ligand engineering. We tested DSCs employing these ruthenium(II) complexes and achieved PCEs of up to 9.4% using cobalt(3+/2+)-based electrolytes, which is the record efficiency to date featuring a ruthenium-based dye. In view of the complicated liquid DSC system, the disagreement found between different characterizations enlightens us about the importance of the sensitizer loading on TiO2, which is a subtle but equally important factor in the electronic properties of the sensitizers.

  13. Chemical and electronic characterization of cobalt in Lanthanumperovskites. Effects of Strontium substitution

    SciTech Connect

    Hueso, Jose L.; Holgado, Juan P.; Pereniguez, Rosa; Mun, Simon; Salmeron, Miquel; Caballero, Alfonso

    2009-02-06

    Two different cobaltites, LaCoO{sub 3} and La{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}}, have been prepared and characterized by means of high energy Co K-edge and low energy O K-edge X-ray absorption spectroscopy (XAS). The partial substitution of La(III) by Sr(II) species induces important changes in the reactivity and electronic state of the perovskite, while little or no changes can be detected in the formal oxidation state of cobalt atoms. The presence of strontium cations induces two main effects in the chemical and electronic behavior of the perovskite. The charge balance with Sr(II) species is reached by the formation of oxygen vacancies throughout the network, which increases the reactivity of the perovskite, now more reducible than the original LaCoO{sub 3} perovskite. O K-edge XAS experiments indicate that the Sr(II) species cause d electrons of cobalt cations to change from low to high spin configuration. Our data allow us to propose that this change in spin multiplicity is induced by the bigger size of Sr(II) cations, which aligns the Co-O-Co atoms, and favors the overlapping of {pi}-symmetry cobalt and oxygen orbitals, reducing the splitting energy of e{sub g} and t{sub 2g} levels.

  14. Intolerability of cobalt salt as erythropoietic agent.

    PubMed

    Ebert, Bastian; Jelkmann, Wolfgang

    2014-03-01

    Unfair athletes seek ways to stimulate erythropoiesis, because the mass of haemoglobin is a critical factor in aerobic sports. Here, the potential misuse of cobalt deserves special attention. Cobalt ions (Co(2+) ) stabilize the hypoxia-inducible transcription factors (HIFs) that increase the expression of the erythropoietin (Epo) gene. Co(2+) is orally active, easy to obtain, and inexpensive. However, its intake can bear risks to health. To elaborate this issue, a review of the pertinent literature was retrieved by a search with the keywords 'anaemia', 'cobalt', 'cobalt chloride', 'erythropoiesis', 'erythropoietin', 'Epo', 'side-effects' and 'treatment', amongst others. In earlier years, cobalt chloride was administered at daily doses of 25 to 300 mg for use as an anti-anaemic agent. Co(2+) therapy proved effective in stimulating erythropoiesis in both non-renal and renal anaemia, yet there were also serious medical adverse effects. The intake of inorganic cobalt can cause severe organ damage, concerning primarily the gastrointestinal tract, the thyroid, the heart and the sensory systems. These insights should keep athletes off taking Co(2+) to stimulate erythropoiesis.

  15. COBALT COMPOUNDS AS ANTIDOTES FOR HYDROCYANIC ACID.

    PubMed

    EVANS, C L

    1964-12-01

    The antidotal potency of a cobalt salt (acetate), of dicobalt edetate, of hydroxocobalamin and of cobinamide against hydrocyanic acid was examined mainly on mice and rabbits. All the compounds were active antidotes for up to twice the LD50; under some conditions for larger doses. The most successful was cobalt acetate for rabbits (5xLD50), which was effective at a molar cyanide/cobalt (CN/Co) ratio of 5, but had as a side-effect intense purgation. Hydroxocobalamin was irregular in action, but on the whole was most effective for mice (4.5xLD50 at a molar ratio of 1), and had no apparent side effects. Dicobalt edetate, at molar ratios of up to 2, was more effective for rabbits (3xLD50) than for mice (2xLD50), but had fewer side effects than cobalt acetate. The effect of thiosulphate was to augment the efficacy of dicobalt edetate and, in mice, that of hydroxocobalamin; but, apparently, in rabbits, to reduce that of hydroxocobalamin. Cobinamide, at a molar ratio of 1, was slightly more effective than hydroxocobalamin on rabbits and also less irregular in its action. Cobalt acetate by mouth was effective against orally administered hydrocyanic acid. The oxygen uptake of the body, reduced by cyanide, is rapidly reinstated when one of the cobalt antidotes has been successfully administered.

  16. Importance of the HIF pathway in cobalt nanoparticle-induced cytotoxicity and inflammation in human macrophages.

    PubMed

    Nyga, Agata; Hart, Alister; Tetley, Teresa D

    2015-01-01

    Recent, unexpected high failure rates of metal-on-metal hip implants have reintroduced the issue of cobalt toxicity. An adverse reaction to cobalt ions and cobalt-induced lung injury occurs during environmental exposure and is now strictly controlled. Currently adverse reaction occurs to cobalt nanoparticles during wear and tear of metal-on-metal hip implants of which the underlying mechanism is not fully understood. The putative role of the hypoxia-inducible factor (HIF) pathway in the mechanism of cobalt nanoparticle (Co-NPs) toxicity was examined using the U937 cell line, human alveolar macrophages and monocyte-derived macrophages. Co-NPs (5-20 μg/ml)-induced cytotoxicity (viability ranged from 75% to <20% of control, respectively) and reactive oxygen species (ROS), whereas a comparable concentration of cobalt ions (Co(II); up to 350 μM) did not. Co-NPs induced HIF-1α stabilization. Addition of ascorbic acid (100 µM) and glutathione (1 mM) both prevented the increased ROS. However, only treatment with ascorbic acid reduced HIF-1α levels and prevented cell death, indicating that a ROS-independent pathway is involved in Co-NPs-induced cytotoxicity. Replenishing intracellular ascorbate, which is crucial in preventing HIF pathway activation, modified Co-induced HIF target gene expression and the inflammatory response, by decreasing interleukin-1 beta (IL-1β) mRNA and protein expression. Addition of glutathione had no effect on Co-NPs-induced HIF target gene expression or inflammatory response. Thus, Co-NPs induce the HIF pathway by depleting intracellular ascorbate, leading to HIF stabilization and pathway activation. This suggests a strong, ROS-independent role for HIF activation in Co-NPs-induced cytotoxicity and a possible role for HIF in metal-on-metal hip implant pathology.

  17. Preparation and characterization of cobalt-substituted anthrax lethal factor

    SciTech Connect

    Saebel, Crystal E.; Carbone, Ryan; Dabous, John R.; Lo, Suet Y.; Siemann, Stefan

    2011-12-09

    Highlights: Black-Right-Pointing-Pointer Cobalt-substituted anthrax lethal factor (CoLF) is highly active. Black-Right-Pointing-Pointer CoLF can be prepared by bio-assimilation and direct exchange. Black-Right-Pointing-Pointer Lethal factor binds cobalt tightly. Black-Right-Pointing-Pointer The electronic spectrum of CoLF reveals penta-coordination. Black-Right-Pointing-Pointer Interaction of CoLF with thioglycolic acid follows a 2-step mechanism. -- Abstract: Anthrax lethal factor (LF) is a zinc-dependent endopeptidase involved in the cleavage of mitogen-activated protein kinase kinases near their N-termini. The current report concerns the preparation of cobalt-substituted LF (CoLF) and its characterization by electronic spectroscopy. Two strategies to produce CoLF were explored, including (i) a bio-assimilation approach involving the cultivation of LF-expressing Bacillus megaterium cells in the presence of CoCl{sub 2}, and (ii) direct exchange by treatment of zinc-LF with CoCl{sub 2}. Independent of the method employed, the protein was found to contain one Co{sup 2+} per LF molecule, and was shown to be twice as active as its native zinc counterpart. The electronic spectrum of CoLF suggests the Co{sup 2+} ion to be five-coordinate, an observation similar to that reported for other Co{sup 2+}-substituted gluzincins, but distinct from that documented for the crystal structure of native LF. Furthermore, spectroscopic studies following the exposure of CoLF to thioglycolic acid (TGA) revealed a sequential mechanism of metal removal from LF, which likely involves the formation of an enzyme: Co{sup 2+}:TGA ternary complex prior to demetallation of the active site. CoLF reported herein constitutes the first spectroscopic probe of LF's active site, which may be utilized in future studies to gain further insight into the enzyme's mechanism and inhibitor interactions.

  18. Loss of hypoxia-inducible factor 2 alpha in the lung alveolar epithelium of mice leads to enhanced eosinophilic inflammation in cobalt-induced lung injury.

    PubMed

    Proper, Steven P; Saini, Yogesh; Greenwood, Krista K; Bramble, Lori A; Downing, Nathaniel J; Harkema, Jack R; Lapres, John J

    2014-02-01

    Hard metal lung disease (HMLD) is an occupational lung disease specific to inhalation of cobalt-containing particles whose mechanism is largely unknown. Cobalt is a known hypoxia mimic and stabilizer of the alpha subunits of hypoxia-inducible factors (HIFs). Previous work revealed that though HIF1α contrib utes to cobalt toxicity in vitro, loss of HIF1α in the alveolar epithelial cells does not provide in vivo protection from cobalt-induced lung inflammation. HIF1α and HIF2α show unique tissue expression profiles, and HIF2α is known to be the predominant HIF mRNA isoform in the adult lung. Thus, if HIF2α activation by cobalt contributes to pathophysiology of HMLD, we hypothesized that loss of HIF2α in lung epithelium would provide protection from cobalt-induced inflammation. Mice with HIF2α-deficiency in Club and alveolar type II epithelial cells (ATIIs) (HIF2α(Δ/Δ)) were exposed to cobalt (60 µg/day) or saline using a subacute occupational exposure model. Bronchoalveolar lavage cellularity, cytokines, qRT-PCR, and histopathology were analyzed. Results show that loss of HIF2α leads to enhanced eosinophilic inflammation and increased goblet cell metaplasia. Additionally, control mice demonstrated a mild recovery from cobalt-induced lung injury compared with HIF2α(Δ/Δ) mice, suggesting a role for epithelial HIF2α in repair mechanisms. The expression of important cytokines, such as interleukin (IL)-5 and IL-10, displayed significant differences following cobalt exposure when HIF2α(Δ/Δ) and control mice were compared. In summary, our data suggest that although loss of HIF2α does not afford protection from cobalt-induced lung inflammation, epithelial HIF2α signaling does play an important role in modulating the inflammatory and repair response in the lung.

  19. Crystal structure of bis-[tris-(1,10-phenanthroline-κ(2) N,N')cobalt(II)] tetra-nitrate N,N'-(1,4-phenyl-enedicarbon-yl)diglycine solvate octa-hydrate.

    PubMed

    Pook, Niels-Patrick; Hentrich, Philipp; Gjikaj, Mimoza

    2015-08-01

    The complex cation of the title compound, [Co(C12H8N2)3]2(NO3)4·C12H12N2O6·8H2O, contains a Co(II) atom with a distorted octa-hedral coordination environment defined by six N atoms from three bidentate 1,10-phenanthroline ligands. The asymmetric unit of the title compound is completed by one-half of the N,N'-(1,4-phenyl-enedicarbon-yl)diglycine solvent mol-ecule, which is located on a centre of inversion, by two nitrate counter-anions and four solvent water mol-ecules. Two [Co(C12H8N2)3](2+) cations are connected through C-H⋯O contacts and through lone-pair⋯π inter-actions involving the non-coordinating N,N'-(1,4-phenyl-enedicarbon-yl)diglycine and phenanthroline mol-ecules. The different aromatic ring systems are involved in π-π stacking and C-H⋯π inter-actions, with centroid-to-centroid distances in the range 3.7094 (8)-3.9973 (9) Å. The crystal structure is stabilized by further anion⋯π inter-actions and C-H⋯O contacts, as well as O-H⋯O and N-H⋯O hydrogen bonds between water mol-ecules, the non-coordinating nitrate anions, N,N'-(1,4-phenyl-enedicarbon-yl)diglycine and phenanthroline mol-ecules. These non-covalent inter-actions give rise to a three-dimensional supra-molecular network.

  20. Removal and recovery of cobalt from aqueous solutions by adsorption using low cost lignocellulosic biomass--coir pith.

    PubMed

    Parab, Harshala; Joshi, Shreeram; Sudersanan, M; Shenoy, Niyoti; Lali, Arvind; Sarma, Umashankar

    2010-01-01

    The applicability of low-cost lignocellulosic biosorbent-coir pith, for removal of cobalt (II) from aqueous solutions using batch adsorption studies has been explored herein. Adsorption characteristics of coir pith were investigated systematically by varying the experimental parameters such as, solution pH, initial metal ion concentration, contact time, adsorbent dose and temperature. The studies revealed that optimum adsorption of cobalt onto coir pith occurred in the pH range of 4.0 - 7.0. Sorption kinetics of cobalt was found to be quite rapid under ambient conditions and the process followed second-order kinetics. The experimental data have been analyzed using non-linearized forms of Langmuir, Freundlich and Redlich-Peterson adsorption isotherms for mathematical description of the process. Desorption studies showed that the quantitative recovery of Co (II) from the spent coir pith was achieved by using 0.5 N HCl. The suitability of this adsorbent for real situation has been observed, when complete removal of cobalt from nuclear power plant coolant water was obtained. The present studies successfully demonstrated the use of coir pith as an efficient adsorbent material for removal of cobalt from aqueous solutions.

  1. Long-term stability for cobalt-based dye-sensitized solar cells obtained by electrolyte optimization.

    PubMed

    Gao, Jiajia; Bhagavathi Achari, Muthuraaman; Kloo, Lars

    2014-06-14

    A significant improvement in the long-term stability for cobalt-based dye-sensitized solar cells (DSCs) under light-soaking conditions has been achieved by optimization of the composition of tris(2,2'-bipyridine) Co(ii)/Co(iii) electrolytes. The effects of component exchanges and changes were also studied during the optimization process.

  2. Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance

    NASA Astrophysics Data System (ADS)

    Qi, B.; Andrew, J. S.; Arnold, D. P.

    2017-03-01

    This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain ( 100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe66Co34) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe2O4) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.

  3. Synergetic interactions improve cobalt leaching from lithium cobalt oxide in microbial fuel cells.

    PubMed

    Huang, Liping; Li, Tianchi; Liu, Chuan; Quan, Xie; Chen, Lijie; Wang, Aijie; Chen, Guohua

    2013-01-01

    Cobalt leaching from lithium cobalt oxide is a promising reduction process for recovery of cobalt and recycle of spent lithium ion batteries, but suffers from consumption of large amount of reductants and energy, and generation of excess secondary polluted sludge. Thus, effective and environmental friendly processes are needed to improve the existing process limitations. Here we reported microbial fuel cells (MFCs) to effectively reduce Co(III) in lithium cobalt oxide with concomitant energy generation. There was a synergetic interaction in MFCs, leading to a more rapid Co(III) leaching at a rate 3.4 times the sum of rates by conventional chemical processes and no-acid controls. External resistor, solid/liquid ratio, solution conductivity, pH and temperature affected system performance. This study provides a new process for recovery of cobalt and recycle of spent lithium ion batteries with concomitant energy generation from MFCs.

  4. Stimulation and Inhibition of Anaerobic Digestion by Nickel and Cobalt: A Rapid Assessment Using the Resazurin Reduction Assay.

    PubMed

    Chen, Jian Lin; Steele, Terry W J; Stuckey, David C

    2016-10-03

    Stimulation of anaerobic digestion by essential trace metals is beneficial from a practical point of view to enhance the biodegradability and degradation rate of wastes. Hence, a quick method to determine which metal species, and at what concentration, can optimize anaerobic digestion is of great interest to both researchers and operators. In this present study, we investigated the effect of nickel(II), cobalt(II), and their mixture, on the anaerobic digestion of synthetic municipal wastewater. Using a volumetric method, that is, measuring methane production over time, revealed that anaerobic digestion was stimulated by the addition of 5 mg L(-1) nickel(II), and cobalt(II), and their mixture in day(s). However, using a novel resazurin reduction assay, and based on its change in rate over time, we evaluated both inhibition at 250 mg L(-1) nickel(II) and cobalt(II), and also the stimulatory effect of 5 mg L(-1) nickel(II), and cobalt(II), and their mixture, in just 6 h. By investigating the dynamic distribution of these metals in the liquid phase of the anaerobic system and kinetics of resazurin reduction by nickel spiked anaerobic sludge, the concentration of nickel(II) on anaerobic digestion performance was profiled. Three critical concentrations were determined; stimulation starting (around 1 mg L(-1)), stimulation ending (around 100 mg L(-1)) and stimulation maximizing (around 10 mg L(-1)). Hence, we propose that the resazurin reduction assay is a novel and quick protocol for studying the stimulation of anaerobic bioprocesses by bioavailable essential trace metals.

  5. Cobalt-containing oxide layers on titanium, their composition, morphology, and catalytic activity in CO oxidation

    NASA Astrophysics Data System (ADS)

    Vasilyeva, M. S.; Rudnev, V. S.; Ustinov, A. Yu.; Korotenko, I. A.; Modin, E. B.; Voitenko, O. V.

    2010-12-01

    In this study possibility to form the layered compositions CoO x + SiO 2/TiO 2/Ti by plasma electrolytic oxidation (PEO) method was shown. Compositions have been obtained by both one-stage PEO method (Method I) with addition of Co(CH 3COO) 2 into silicate electrolyte and impregnation of preliminary obtained by the PEO method SiO 2/TiO 2/Ti systems in aqueous solutions containing cobalt salts with their following annealing (Method II). XRD, XPS and SEM/EDX were used to investigate the phase and element composition, microstructure of the coatings prepared by the two various methods. Catalytic activity of the cobalt-containing composites was investigated in the CO oxidation reaction. Under experimental conditions, the structures obtained by impregnation and annealing method were more active, than those obtained by one-stage PEO method. The surface structures of cobalt-containing coatings obtained by the PEO method and by impregnation and annealing differ in both quantitative and qualitative relation. The cobalt content on the surface of impregnating coatings is three times as much as that for those formed by one-stage PEO method. It is found that coatings obtained by the Method II have a more developed surface. The surface of CoO x + SiO 2/TiO 2/Ti compositions obtained by the PEO method contains, presumably Co(OH) 2 and Co 3O 4. The surface of the similar compositions obtained by the Method II, possibly contains CoO, either Co 2O 3, or CoOOH. The combination of these factors, perhaps, also provides a higher activity of the compositions formed by the Method II.

  6. Catalytic dioxygen activation by Co(II) complexes employing a coordinatively versatile ligand scaffold.

    PubMed

    Sharma, Savita K; May, Philip S; Jones, Matthew B; Lense, Sheri; Hardcastle, Kenneth I; MacBeth, Cora E

    2011-02-14

    The ligand bis(2-isobutyrylamidophenyl)amine has been prepared and used to stabilize both mononuclear and dinuclear cobalt(II) complexes. The nuclearity of the cobalt product is regulated by the deprotonation state of the ligand. Both complexes catalytically oxidize triphenylphosphine to triphenylphosphine oxide in the presence of O(2).

  7. Synthesis of cobalt-containing mesoporous catalysts using the ultrasonic-assisted “pH-adjusting” method: Importance of cobalt species in styrene oxidation

    SciTech Connect

    Li, Baitao Zhu, Yanrun; Jin, Xiaojing

    2015-01-15

    Cobalt-containing SBA-15 and MCM-41 (Co-SBA-15 and Co-MCM-41) mesoporous catalysts were prepared via ultrasonic-assisted “pH-adjusting” technique in this study. Their physiochemical structures were comprehensively characterized and correlated with catalytic activity in oxidation of styrene. The nature of cobalt species depended on the type of mesoporous silica as well as pH values. The different catalytic performance between Co-SBA-15 and Co-MCM-41 catalysts originated from cobalt species. Cobalt species were homogenously incorporated into the siliceous framework of Co-SBA-15 in single-site Co(II) state, while Co{sub 3}O{sub 4} particles were loaded on Co-MCM-41 catalysts. The styrene oxidation tests showed that the single-site Co(II) state was more beneficial to the catalytic oxidation of styrene. The higher styrene conversion and benzaldehyde selectivity over Co-SBA-15 catalysts were mainly attributed to single-site Co(II) state incorporated into the framework of SBA-15. The highest conversion of styrene (34.7%) with benzaldehyde selectivity of 88.2% was obtained over Co-SBA-15 catalyst prepared at pH of 7.5, at the mole ratio of 1:1 (styrene to H{sub 2}O{sub 2}) at 70 °C. - Graphical abstract: Cobalt-containing mesoporous silica catalysts were developed via ultrasonic-assisted “pH-adjusting” technique. Compared with Co{sub 3}O{sub 4} in Co-MCM-41, the single-site Co(II) state in Co-SBA-15 was more efficient for the styrene oxidation. - Highlights: • Fast and cost-effective ultrasonic technique for preparing mesoporous materials. • Incorporation of Co via ultrasonic irradiation and “pH-adjusting”. • Physicochemical comparison between Co-SBA-15 and Co-MCM-41. • Correlation of styrene oxidation activity and catalyst structural property.

  8. Cobalt: A vital element in the aircraft engine industry

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.

    1981-01-01

    Recent trends in the United States consumption of cobalt indicate that superalloys for aircraft engine manufacture require increasing amounts of this strategic element. Superalloys consume a lion's share of total U.S. cobalt usage which was about 16 million pounds in 1980. In excess of 90 percent of the cobalt used in this country was imported, principally from the African countries of Zaire and Zambia. Early studies on the roles of cobalt as an alloying element in high temperature alloys concentrated on the simple Ni-Cr and Nimonic alloy series. The role of cobalt in current complex nickel base superalloys is not well defined and indeed, the need for the high concentration of cobalt in widely used nickel base superalloys is not firmly established. The current cobalt situation is reviewed as it applies to superalloys and the opportunities for research to reduce the consumption of cobalt in the aircraft engine industry are described.

  9. Crystal structure of catena-poly[[aqua(2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)cobalt(II)]-μ-cyanido-κ2 N:C-[dicyanidoplatinum(II)]-μ-cyanido-κ2 C:N

    PubMed Central

    White, Frankie; Sykora, Richard E.

    2014-01-01

    The title compound, [Co(C15H11N3)(H2O){Pt(CN)4}]n, is a one-dimensional coordination polymer formed under hydro­thermal reaction conditions. The CoII site has sixfold coordination with a distorted octa­hedral geometry, while the PtII ion is coordinated by four cyanide groups in an almost regular square-planar geometry. The compound contains twofold rotation symmetry about its CoII ion, the water molecule and the terpyridine ligand, and the PtII atom resides on an inversion center. trans-Bridging by the tetra­cyanidoplatinate(II) anions links the CoII cations, forming chains parallel to [-101]. Additionally, each CoII atom is coordin­ated by one water mol­ecule and one tridentate 2,2′:6′,2′′-terpyridine ligand. O—H⋯N hydrogen-bonding inter­actions are found between adjacent chains and help to consolidate the crystal packing. In addition, relatively weak π–π stacking inter­actions exist between the terpyridine ligands of adjacent chains [inter­planar distance = 3.464 (7) Å]. No Pt⋯Pt inter­actions are observed in the structure. PMID:25309181

  10. Synthesis, magnetic properties and dynamic behavior of cobalt complexes with an anthracene-containing dioxolene ligand.

    PubMed

    Katayama, Koichi; Hirotsu, Masakazu; Kinoshita, Isamu; Teki, Yoshio

    2014-09-21

    The anthracene-functionalized cobalt complexes [Co(L)(TPA)]PF6 (1) and [Co(L)(Me(n)TPA)]PF6 (2, n = 1; 3, n = 2; 4, n = 3) were synthesized by the combination of 9-(3,4-dihydroxyphenyl)anthracene (H2L) and tris(2-pyridylmethyl)amine (TPA) or its derivatives (Me(n)TPA, n = 1, 2, 3). Characterization of complexes 1-4 was performed by UV-vis absorption, IR, (1)H NMR, and magnetic susceptibility measurements. In the solid state, the variable-temperature magnetic susceptibility data showed that complex 1 is low-spin cobalt(III) catecholate (Co(III)(LS)-Cat), while complex 4 is high-spin cobalt(II) semiquinonate (Co(II)(HS)-SQ) in the range 4.5-400 K. The susceptibility data of complexes 2 and 3 suggested valence tautomerism between the Co(III)(LS)-Cat and Co(II)(HS)-SQ forms. Light-induced valence tautomerism was observed in complexes 2 and 3 at 5 K by photo-irradiation. In solution, the temperature dependence of (1)H NMR spectra of 1 and 2 showed an equilibrium between their geometrical isomers.

  11. Synthesis, Structural and Spectroscopic Characterization, and Reactivities of Mononuclear Cobalt(III)-Peroxo Complexes

    PubMed Central

    Cho, Jaeheung; Sarangi, Ritimukta; Kang, Hye Yeon; Lee, Jung Yoon; Kubo, Minoru; Ogura, Takashi; Solomon, Edward I.; Nam, Wonwoo

    2010-01-01

    Metal-dioxygen adducts are key intermediates detected in the catalytic cycles of dioxygen activation by metalloenzymes and biomimetic compounds. In this study, mononuclear cobalt(III)- peroxo complexes bearing tetraazamacrocyclic ligands, [Co(12-TMC)(O2)]+ and [Co(13-TMC)(O2)]+, were synthesized by reacting [Co(12-TMC)(CH3CN)]2+ and [Co(13-TMC)(CH3CN)]2+, respectively, with H2O2 in the presence of triethylamine. The mononuclear cobalt(III)-peroxo intermediates were isolated and characterized by various spectroscopic techniques and X-ray crystallography, and the structural and spectroscopic characterization demonstrated unambiguously that the peroxo ligand is bound in a side-on η2 fashion. The O-O bond stretching frequency of [Co(12-TMC)(O2)]+ and [Co(13- TMC)(O2)]+ was determined to be 902 cm−1 by resonance Raman spectroscopy. The structural properties of the CoO2 core in both complexes are nearly identical; the O-O bond distances of [Co(12-TMC)(O2)]+ and [Co(13-TMC)(O2)]+ were 1.4389(17) Å and 1.438(6) Å, respectively. The cobalt(III)-peroxo complexes showed reactivities in the oxidation of aldehydes and O2-transfer reactions. In the aldehyde oxidation reactions, the nucleophilic reactivity of the cobalt-peroxo complexes was significantly dependent on the ring size of the macrocyclic ligands, with the reactivity of [Co(13-TMC)(O2)]+ > [Co(12-TMC)(O2)]+. In the O2-transfer reactions, the cobalt(III)-peroxo complexes transferred the bound peroxo group to a manganese(II) complex, affording the corresponding cobalt(II) and manganese(III)- peroxo complexes. The reactivity of the cobalt-peroxo complexes in O2-transfer was also significantly dependent on the ring size of tetraazamacrocycles, and the reactivity order in the O2-transfer reactions was the same as that observed in the aldehyde oxidation reactions. PMID:21062059

  12. Synthesis of Samarium Cobalt Nanoblades

    SciTech Connect

    Darren M. Steele

    2010-08-25

    As new portable particle acceleration technologies become feasible the need for small high performance permanent magnets becomes critical. With particle accelerating cavities of a few microns, the photonic crystal fiber (PCF) candidate demands magnets of comparable size. To address this need, samarium cobalt (SmCo) nanoblades were attempted to be synthesized using the polyol process. Since it is preferable to have blades of 1-2 {micro}m in length, key parameters affecting size and morphology including method of stirring, reaction temperature, reaction time and addition of hydroxide were examined. Nanoparticles consisting of 70-200 nm spherical clusters with a 3-5 nm polyvinylpyrrolidone (PVP) coating were synthesized at 285 C and found to be ferromagnetic. Nanoblades of 25nm in length were observed at the surface of the nanoclusters and appeared to suggest agglomeration was occurring even with PVP employed. Morphology and size were characterized using a transmission electron microscope (TEM). Powder X-Ray Diffraction (XRD) analysis was conducted to determine composition but no supportive evidence for any particular SmCo phase has yet been observed.

  13. Fast Low-Spin Cobalt Complex Redox Shuttles for Dye-Sensitized Solar Cells.

    PubMed

    Xie, Yuling; Hamann, Thomas W

    2013-01-17

    A low-spin cobalt(II) complex, cobalt bis(trithiacyclononane), [Co(ttcn)2](3+/2+), was investigated for use as a redox shuttle in dye-sensitized solar cells, DSSCs. This unique cobalt complex redox shuttle is stable, transparent, and easy to synthesize from commercial ligands and has attractive energetic and kinetic features for use in DSSCs. Initial results indicate that the overall performance is limited by recombination. Variation of the sensitizer and deposition of an ultrathin coating of alumina on nanoparticle-based TiO2 DSSC photoanodes reduced recombination, which resulted in significantly improved quantum yields. The photovoltaic behavior was compared to the current record efficiency cobalt tris-bipyridine, [Co(bpy)3](3+/2+), redox shuttle and produced similar results. Further use of high extinction organic sensitizers with only ∼200 mV of driving force for regeneration was examined, which produced efficiencies of over 2%; importantly, regeneration is not rate-limiting in this system, thus demonstrating the promise of using such fast redox shuttles.

  14. Enzyme deactivation due to metal-ion dissociation during turnover of the cobalt-beta-lactamase catalyzed hydrolysis of beta-lactams.

    PubMed

    Badarau, Adriana; Page, Michael I

    2006-09-12

    Metallo-beta-lactamases are native zinc enzymes that catalyze the hydrolysis of beta-lactam antibiotics but are also able to function with cobalt (II) and require one or two metal ions for catalytic activity. The kinetics of the hydrolysis of benzylpenicillin catalyzed by cobalt substituted beta-lactamase from Bacillus cereus (BcII) are biphasic. The dependence of enzyme activity on pH and metal-ion concentration indicates that only the di-cobalt enzyme is catalytically active. A mono-cobalt enzyme species is formed during the catalytic cycle, which is virtually inactive and requires the association of another cobalt ion for turnover. Two intermediates with different metal to enzyme stoichiometries are formed on a branched reaction pathway. The di-cobalt enzyme intermediate is responsible for the direct catalytic route, which is pH-independent between 5.5 and 9.5 but is also able to slowly lose one bound cobalt ion via the branching route to give the mono-cobalt inactive enzyme intermediate. This inactivation pathway of metal-ion dissociation occurs by both an acid catalyzed and a pH-independent reaction, which is dependent on the presence of an enzyme residue of pK(a) = 8.9 +/- 0.1 in its protonated form and shows a large kinetic solvent isotope effect (H(2)O/D(2)O) of 5.2 +/- 0.5, indicative of a rate-limiting proton transfer. The pseudo first-order rate constant to regenerate the di-cobalt beta-lactamase from the mono-cobalt enzyme intermediate has a first-order dependence on cobalt-ion concentration in the pH range 5.5-9.5. The second-order rate constant for metal-ion association is dependent on two groups of pK(a) 6.32 +/- 0.1 and 7.47 +/- 0.1 being in their deprotonated basic forms and one group of pK(a) 9.48 +/- 0.1 being in its protonated form.

  15. Equilibrium phase boundary between hcp-cobalt and fcc-cobalt

    NASA Astrophysics Data System (ADS)

    Cynn, Hyunchae; Lipp, Magnus J.; Evans, William J.; Baer, Bruce J.

    In 2000 (Yoo et al., PRL), fcc-cobalt was reported as a new high pressure phase transforming from ambient hcp-cobalt starting at around 105 GPa and 300 K. Both cobalts coexist up to 150 GPa and thereafter only fcc-cobalt was found to be the only stable phase to 200 GPa. Our recent synchrotron x-ray diffraction data on cobalt are at odds with the previous interpretation. We will present our new finding and elaborate on our understanding in terms of the equilibrium phase boundary of cobalt. We will also compare our previous work on xenon (Cynn et al., 2001, PRL) with our new results on cobalt. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Portions of this work were performed at HPCAT (Sector 16), APS, Argonne National Laboratory. HPCAT operations are supported by DOE-NNSA under Award No. DENA0001974 and DOE-BES under Award No. DE-FG02-99ER45775. The Advanced Photon Source is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

  16. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium...

  17. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium...

  18. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium...

  19. Palladium-cobalt particles as oxygen-reduction electrocatalysts

    DOEpatents

    Adzic, Radoslav; Huang, Tao

    2009-12-15

    The present invention relates to palladium-cobalt particles useful as oxygen-reducing electrocatalysts. The invention also relates to oxygen-reducing cathodes and fuel cells containing these palladium-cobalt particles. The invention additionally relates to methods for the production of electrical energy by using the palladium-cobalt particles of the invention.

  20. Crystal structures of triazine-3-thione derivatives by reaction with copper and cobalt salts.

    PubMed

    López-Torres, Elena; Mendiola, Maria Antonia; Pastor, César J

    2006-04-03

    The reaction of 5-methoxy-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]triazine-3-thione L1H2OCH3 with copper(II) chloride leads to the formation of an organic molecule L2 containing two triazine rings linked by a new S-S bond. A binuclear copper(II) complex, 1, containing L1 is also isolated. The reaction of L1H2OCH3 with copper(I) chloride yields a hexanuclear cluster of copper(I), 2, in which the copper atoms form a distorted octahedron with the ligand L1 acting as an NS chelate and sulfur bridge, giving to the copper ion a trigonal geometry by one N and two S atoms. In any reaction of the disulfide L2 with metal salts, complexes containing this molecule are isolated. Reactions with copper(I) and copper(II) chloride and nickel(II) and cadmium(II) nitrate produce the S-S bond cleavage, giving complexes containing the triazine L1 behaving as the NS anion, which show spectroscopic characteristics identical with those formed by reaction with L1H2OCH3. However, the reaction with cobalt(II) nitrate gives a low-spin octahedral cobalt(III) complex, in which an asymmetric rupture of the disulfide L2 has been produced, giving an unexpected complex with a new ligand and keeping the S-S bond.

  1. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung epithelial cells.

    PubMed

    Xie, Hong; Smith, Leah J; Holmes, Amie L; Zheng, Tongzhang; Pierce Wise, John

    2016-05-01

    Cobalt is a toxic metal used in various industrial applications leading to adverse lung effects by inhalation. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells, especially normal lung epithelial cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in normal primary human lung epithelial cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble and particulate cobalt induced similar cytotoxicity while soluble cobalt was more genotoxic than particulate cobalt. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung epithelial cells.

  2. Controlled cobalt doping in biogenic magnetite nanoparticles

    PubMed Central

    Byrne, J. M.; Coker, V. S.; Moise, S.; Wincott, P. L.; Vaughan, D. J.; Tuna, F.; Arenholz, E.; van der Laan, G.; Pattrick, R. A. D.; Lloyd, J. R.; Telling, N. D.

    2013-01-01

    Cobalt-doped magnetite (CoxFe3 −xO4) nanoparticles have been produced through the microbial reduction of cobalt–iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mössbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe2+ site with Co2+, with up to 17 per cent Co substituted into tetrahedral sites. PMID:23594814

  3. Nickel cobalt phosphorous low stress electroplating

    NASA Technical Reports Server (NTRS)

    Engelhaupt, Darell E. (Inventor); Ramsey, Brian D. (Inventor)

    2002-01-01

    An electrolytic plating process is provided for electrodepositing a nickel or nickel cobalt alloy which contains at least about 2% to 25% by atomic volume of phosphorous. The process solutions contains nickel and optionally cobalt sulfate, hypophosphorous acid or a salt thereof, boric acid or a salt thereof, a monodentate organic acid or a salt thereof, and a multidentate organic acid or a salt thereof. The pH of the plating bath is from about 3.0 to about 4.5. An electroplating process is also provided which includes electroplating from the bath a nickel or nickel cobalt phosphorous alloy. This process can achieve a deposit with high microyield of at least about 84 kg/mm.sup.2 (120 ksi) and a density lower than pure nickel of about 8.0 gm/cc. This process can be used to plate a deposit of essentially zero stress at plating temperatures from ambient to 70.degree. C.

  4. Rapid phase synthesis of nanocrystalline cobalt ferrite

    SciTech Connect

    Shanmugavel, T.; Raj, S. Gokul; Rajarajan, G.; Kumar, G. Ramesh

    2014-04-24

    Synthesis of single phase nanocrystalline Cobalt Ferrite (CoFe{sub 2}O{sub 4}) was achieved by single step autocombustion technique with the use of citric acid as a chelating agent in mono proportion with metal. Specimens prepared with this method showed significantly higher initial permeability's than with the conventional process. Single phase nanocrystalline cobalt ferrites were formed at very low temperature. Surface morphology identification were carried out by transmission electron microscopy (TEM) analysis. The average grain size and density at low temperature increased gradually with increasing the temperature. The single phase formation is confirmed through powder X-ray diffraction analysis. Magnetization measurements were obtained at room temperature by using a vibrating sample magnetometer (VSM), which showed that the calcined samples exhibited typical magnetic behaviors. Temperature dependent magnetization results showed improved behavior for the nanocrystalline form of cobalt ferrite when compared to the bulk nature of materials synthesized by other methods.

  5. Syntheses and Properties of Cobalt and Nickel Hydroxide Nanosheets

    NASA Astrophysics Data System (ADS)

    Kurashina, Masashi; Eguchi, Akio; Kanezaki, Eiji; Shiga, Takuya; Oshio, Hiroki

    Nanosheets of cobalt and nickel hydroxides nanosheets were prepared by delamination of layered compounds, CoII(OH)1.73(DBS)0.27·0.87H2O (Co-DBS, DBS = dodecylbenzene sulfonate) and NiII(OH)1.63(DBS)0.37·1.24H2O (Ni-DBS), respectively. Powder X-ray diffraction analyses of the layered compounds revealed lattice parameters of a0 = 3.07 Å and c0 = 30 Å (Co-DBS) and a0 = 3.09 Å and c0 = 30 Å (Ni-DBS) in the hexagonal system. Dispersions of Co-DBS and Ni-DBS in 1-butanol produced colloidal solutions of nanosheets, [Co-DBS]delam and [Ni-DBS]delam, respectively. Poly(vinylpyrrolidone) (PVP) was dissolved in [Co-DBS]delam and [Ni-DBS]delam and the mixtures were dried to yield Co-PVP and Ni-PVP, respectively. These nanosheets measured 150-500 nm for [Co-DBS]delam and 135-400 nm for [Ni-DBS]delam by means of dynamic light scattering. Atomic force microscopy images showed lateral dimensions of 100-500 nm for [Co-DBS]delam and 50-100 nm for [Ni-DBS]delam. In the former image, the cobalt hydroxide nanosheets had a fairly flat terrace structure with thickness of 3.1-3.6 nm and with aspect ratios of 30-150, whereas in the latter image dome-like nanosheets of nickel hydroxide with height of 2.2-2.3 nm were confirmed. These nanosheets were regarded as monolayer. Magnetization experiments at 1.8 K showed hysteresis loops for Co-DBS, Co-PVP, Ni-DBS, and Ni-PVP.

  6. DNA Cleavage, Cytotoxic Activities, and Antimicrobial Studies of Ternary Copper(II) Complexes of Isoxazole Schiff Base and Heterocyclic Compounds

    PubMed Central

    Chityala, Vijay Kumar; Sathish Kumar, K.; Macha, Ramesh; Tigulla, Parthasarathy; Shivaraj

    2014-01-01

    Novel mixed ligand bivalent copper complexes [Cu. L. A. ClO4] and [Cu. L. A] where “L” is Schiff bases, namely 2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-bromophenol (DMIIMBP)/2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-chlorophenol (DMIIMCP), and “A” is heterocyclic compound, such as 1,10-phenanthroline (phen)/2,21-bipyridyl (bipy)/8-hydroxyquinoline (oxine)/5-chloro-8-hydroxyquinoline (5-Cl-oxine), have been synthesized. These complexes have been characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, TG, and DTA. On the basis of spectral studies and analytical data, five-coordinated square pyramidal/four-coordinated square planar geometry is assigned to all complexes. The ligands and their ternary complexes with Cu(II) have been screened for antimicrobial activity against bacteria and fungi by paper disc method. The antimicrobial studies of Schiff bases and their metal complexes showed significant activity and further it is observed that the metal complexes showed more activity than corresponding Schiff bases. In vitro antitumor activity of Cu(II) complexes was assayed against human cervical carcinoma (HeLa) cancer cells and it was observed that few complexes exhibit good antitumor activity on HeLa cell lines. The DNA cleavage studies have also been carried out on pBR 322 and it is observed that these Cu(II) complexes are capable of cleaving supercoiled plasmid DNA in the presence of H2O2 and UV light. PMID:24895493

  7. A Hyperactive Cobalt-Substituted Extradiol-Cleaving Catechol Dioxygenase

    PubMed Central

    Fielding, Andrew J.; Farquhar, Erik R.

    2011-01-01

    Homoprotocatechuate (HPCA) 2,3-dioxygenase from Brevibacterium fuscum (Fe-HPCD) has an Fe(II) center in its active site that can be replaced with Mn(II) or Co(II). While Mn-HPCD exhibits steady state kinetic parameters comparable to those of Fe-HPCD, Co-HPCD behaves somewhat differently exhibiting a significantly higher KMO2 and kcat. The high activity of Co-HPCD is surprising, given that cobalt has the highest standard M(III/II) redox potential of the three metals. Comparison of the X-ray crystal structures of the resting and substrate-bound forms of Fe-, Mn-, and Co-HPCD shows that metal-substitution has no effect on the local ligand environment, the conformational integrity of the active site, or the overall protein structure, suggesting that the protein structure does not differentially tune the potential of the metal center. Analysis of the steady state kinetics of Co-HPCD suggests that the Co(II) center alters the relative rate constants for the interconversion of intermediates in the catalytic cycle but still allows the dioxygenase reaction to proceed efficiently. When compared with the kinetic data for Fe- and Mn-HPCD, these results show that dioxygenase catalysis can proceed at high rates over a wide range of metal redox potentials. This is consistent with the proposed mechanism in which the metal mediates electron transfer between the catechol substrate and O2 to form the postulated [M(II)(semiquinone)superoxo] reactive species. These kinetic differences and the spectroscopic properties of Co-HPCD provide new tools with which to explore the unique O2 activation mechanism associated with the extradiol dioxygenase family. PMID:21153851

  8. Cation distributions on rapidly solidified cobalt ferrite

    NASA Technical Reports Server (NTRS)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  9. Alterations of histone modifications by cobalt compounds

    PubMed Central

    Li, Qin; Ke, Qingdong; Costa, Max

    2009-01-01

    In the present study, we examined the effects of CoCl2 on multiple histone modifications at the global level. We found that in both human lung carcinoma A549 cells and human bronchial epithelial Beas-2B cells, exposure to CoCl2 (≥200 μM) for 24 h increased H3K4me3, H3K9me2, H3K9me3, H3K27me3, H3K36me3, uH2A and uH2B but decreased acetylation at histone H4 (AcH4). Further investigation demonstrated that in A549 cells, the increase in H3K4me3 and H3K27me3 by cobalt ions exposure was probably through enhancing histone methylation processes, as methionine-deficient medium blocked the induction of H3K4me3 and H3K27me3 by cobalt ions, whereas cobalt ions increased H3K9me3 and H3K36me3 by directly inhibiting JMJD2A demethylase activity in vitro, which was probably due to the competition of cobalt ions with iron for binding to the active site of JMJD2A. Furthermore, in vitro ubiquitination and deubiquitination assays revealed that the cobalt-induced histone H2A and H2B ubiquitination is the result of inhibition of deubiquitinating enzyme activity. Microarray data showed that exposed to 200 μM of CoCl2 for 24 h, A549 cells not only increased but also decreased expression of hundreds of genes involved in different cellular functions, including tumorigenesis. This study is the first to demonstrate that cobalt ions altered epigenetic homeostasis in cells. It also sheds light on the possible mechanisms involved in cobalt-induced alteration of histone modifications, which may lead to altered programs of gene expression and carcinogenesis since cobalt at higher concentrations is a known carcinogen. PMID:19376846

  10. Cobalt pivalate complex as a catalyst for liquid phase oxidation of n-hexane

    NASA Astrophysics Data System (ADS)

    Moskovskaya, I. F.; Maerle, A. A.; Shvydkiy, N. V.; Romanovsky, B. V.; Ivanova, I. I.

    2015-09-01

    Catalytic properties of cobalt(II) pivalate complex as both individual and supported on mesoporous molecular sieves Si-KIT-6, Al-KIT-6, and Ce-KIT-6 were investigated in liquid-phase oxidation of n-hexane with molecular oxygen. This complex was shown to be an active and selective catalyst for the oxidation of n-C6H14 into C1-C4 carboxylic acids. The activity of Co(II) pivalate remains practically unchanged on heterogenizing the complex on molecular sieve supports. At the same time, its selectivity and resistance towards an oxidative degradation are slightly increased.

  11. Effect of cobalt on the primary productivity of Spirulina platensis

    SciTech Connect

    Sharma, R.M.; Panigrahi, S.; Azeez, P.A.

    1987-10-01

    Cobalt, a micronutrient for biological organisms, is a metal of wide use. Main sources of Co to the environment are combustion of fossil fuels, smelters, cobalt processing facilities, sewage and industrial wastes. Atomic power plants and nuclear weapon detonations form an important source of radioisotopes of this metal to the environment. Cobalt has been included in the 14 toxic trace elements of critical importance from the point of view of environmental pollution and health hazards. Cobalt deficiency leads to diseases like stunted growth. At toxic level, Co inhibits heme biosynthesis and enzyme activities. The present study reports the effect of cobalt on biomass productivity of blue-green alga Spirulina platensis.

  12. Cobalt(II) Ammine Complexes as Reversible Absorbers of Oxygen.

    ERIC Educational Resources Information Center

    Saito, Kazuo; Ogino, Kazuko

    1988-01-01

    Describes experiments designed to measure the oxygen content in the atmosphere and related areas in the high school laboratories. Considers the application of these activities to other programs. Includes a description of the binuclear complex and recommended procedures. (CW)

  13. Chemical vapor deposition of low reflective cobalt (II) oxide films

    NASA Astrophysics Data System (ADS)

    Amin-Chalhoub, Eliane; Duguet, Thomas; Samélor, Diane; Debieu, Olivier; Ungureanu, Elisabeta; Vahlas, Constantin

    2016-01-01

    Low reflective CoO coatings are processed by chemical vapor deposition from Co2(CO)8 at temperatures between 120 °C and 190 °C without additional oxygen source. The optical reflectivity in the visible and near infrared regions stems from 2 to 35% depending on deposition temperature. The combination of specific microstructural features of the coatings, namely a fractal ⿿cauliflower⿿ morphology and a grain size distribution more or less covering the near UV and IR wavelength ranges enhance light scattering and gives rise to a low reflectivity. In addition, the columnar morphology results in a density gradient in the vertical direction that we interpret as a refractive index gradient lowering reflectivity further down. The coating formed at 180 °C shows the lowest average reflectivity (2.9%), and presents an interesting deep black diffuse aspect.

  14. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung fibroblast cells.

    PubMed

    Smith, Leah J; Holmes, Amie L; Kandpal, Sanjeev Kumar; Mason, Michael D; Zheng, Tongzhang; Wise, John Pierce

    2014-08-01

    Cobalt exposure is increasing as cobalt demand rises worldwide due to its use in enhancing rechargeable battery efficiency, super-alloys, and magnetic products. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in human lung cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble cobalt was more cytotoxic than particulate cobalt while particulate and soluble cobalt induced similar levels of genotoxicity. However, soluble cobalt induced cell cycle arrest indicated by the lack of metaphases at much lower intracellular cobalt concentrations compared to cobalt oxide. Accordingly, we investigated the role of particle internalization in cobalt oxide-induced toxicity and found that particle-cell contact was necessary to induce cytotoxicity and genotoxicity after cobalt exposure. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung fibroblasts, and solubility plays a key role in cobalt-induced lung toxicity.

  15. Preparation of cobalt nanoparticles by hydrogen reduction of cobalt chloride in the gas phase

    SciTech Connect

    Jang, Hee Dong; Hwang, Dae Won; Kim, Dong Pyo; Kim, Heon Chang; Lee, Byung Yoon; Jeong, In Bum

    2004-01-03

    Cobalt nanoparticles were produced by the hydrogen reduction of cobalt chloride vapor in a multistage tubular aerosol flow reactor. Reaction zone temperature, preheating temperature, mole fractions of CoCl{sub 2} and H{sub 2}, and residence time were considered as key process variables for the control of particle size and size distribution. Ranging from 50 to 78 nm in average diameter, cobalt nanoparticles with narrow size distributions were synthesized throughout our experiments. All of the considered process variables affected the particle size and size distribution in the synthesis of cobalt nanoparticles. As the reaction zone temperature and the CoCl{sub 2} mole fraction increased, the average particle diameter increased. But the average particle diameter decreased as the residence time of reactants increased.

  16. Exposure to Cobalt Causes Transcriptomic and Proteomic Changes in Two Rat Liver Derived Cell Lines

    PubMed Central

    Permenter, Matthew G.; Dennis, William E.; Sutto, Thomas E.; Jackson, David A.; Lewis, John A.; Stallings, Jonathan D.

    2013-01-01

    Cobalt is a transition group metal present in trace amounts in the human diet, but in larger doses it can be acutely toxic or cause adverse health effects in chronic exposures. Its use in many industrial processes and alloys worldwide presents opportunities for occupational exposures, including military personnel. While the toxic effects of cobalt have been widely studied, the exact mechanisms of toxicity remain unclear. In order to further elucidate these mechanisms and identify potential biomarkers of exposure or effect, we exposed two rat liver-derived cell lines, H4-II-E-C3 and MH1C1, to two concentrations of cobalt chloride. We examined changes in gene expression using DNA microarrays in both cell lines and examined changes in cytoplasmic protein abundance in MH1C1 cells using mass spectrometry. We chose to closely examine differentially expressed genes and proteins changing in abundance in both cell lines in order to remove cell line specific effects. We identified enriched pathways, networks, and biological functions using commercial bioinformatic tools and manual annotation. Many of the genes, proteins, and pathways modulated by exposure to cobalt appear to be due to an induction of a hypoxic-like response and oxidative stress. Genes that may be differentially expressed due to a hypoxic-like response are involved in Hif-1α signaling, glycolysis, gluconeogenesis, and other energy metabolism related processes. Gene expression changes linked to oxidative stress are also known to be involved in the NRF2-mediated response, protein degradation, and glutathione production. Using microarray and mass spectrometry analysis, we were able to identify modulated genes and proteins, further elucidate the mechanisms of toxicity of cobalt, and identify biomarkers of exposure and effect in vitro, thus providing targets for focused in vivo studies. PMID:24386269

  17. Exposure to cobalt causes transcriptomic and proteomic changes in two rat liver derived cell lines.

    PubMed

    Permenter, Matthew G; Dennis, William E; Sutto, Thomas E; Jackson, David A; Lewis, John A; Stallings, Jonathan D

    2013-01-01

    Cobalt is a transition group metal present in trace amounts in the human diet, but in larger doses it can be acutely toxic or cause adverse health effects in chronic exposures. Its use in many industrial processes and alloys worldwide presents opportunities for occupational exposures, including military personnel. While the toxic effects of cobalt have been widely studied, the exact mechanisms of toxicity remain unclear. In order to further elucidate these mechanisms and identify potential biomarkers of exposure or effect, we exposed two rat liver-derived cell lines, H4-II-E-C3 and MH1C1, to two concentrations of cobalt chloride. We examined changes in gene expression using DNA microarrays in both cell lines and examined changes in cytoplasmic protein abundance in MH1C1 cells using mass spectrometry. We chose to closely examine differentially expressed genes and proteins changing in abundance in both cell lines in order to remove cell line specific effects. We identified enriched pathways, networks, and biological functions using commercial bioinformatic tools and manual annotation. Many of the genes, proteins, and pathways modulated by exposure to cobalt appear to be due to an induction of a hypoxic-like response and oxidative stress. Genes that may be differentially expressed due to a hypoxic-like response are involved in Hif-1α signaling, glycolysis, gluconeogenesis, and other energy metabolism related processes. Gene expression changes linked to oxidative stress are also known to be involved in the NRF2-mediated response, protein degradation, and glutathione production. Using microarray and mass spectrometry analysis, we were able to identify modulated genes and proteins, further elucidate the mechanisms of toxicity of cobalt, and identify biomarkers of exposure and effect in vitro, thus providing targets for focused in vivo studies.

  18. Responses of two scleractinian corals to cobalt pollution and ocean acidification.

    PubMed

    Biscéré, Tom; Rodolfo-Metalpa, Riccardo; Lorrain, Anne; Chauvaud, Laurent; Thébault, Julien; Clavier, Jacques; Houlbrèque, Fanny

    2015-01-01

    The effects of ocean acidification alone or in combination with warming on coral metabolism have been extensively investigated, whereas none of these studies consider that most coral reefs near shore are already impacted by other natural anthropogenic inputs such as metal pollution. It is likely that projected ocean acidification levels will aggravate coral reef health. We first investigated how ocean acidification interacts with one near shore locally abundant metal on the physiology of two major reef-building corals: Stylophora pistillata and Acropora muricata. Two pH levels (pHT 8.02; pCO2 366 μatm and pHT 7.75; pCO2 1140 μatm) and two cobalt concentrations (natural, 0.03 μg L-1 and polluted, 0.2 μg L-1) were tested during five weeks in aquaria. We found that, for both species, cobalt input decreased significantly their growth rates by 28% while it stimulated their photosystem II, with higher values of rETRmax (relative Electron Transport Rate). Elevated pCO2 levels acted differently on the coral rETRmax values and did not affect their growth rates. No consistent interaction was found between pCO2 levels and cobalt concentrations. We also measured in situ the effect of higher cobalt concentrations (1.06 ± 0.16 μg L-1) on A. muricata using benthic chamber experiments. At this elevated concentration, cobalt decreased simultaneously coral growth and photosynthetic rates, indicating that the toxic threshold for this pollutant has been reached for both host cells and zooxanthellae. Our results from both aquaria and in situ experiments, suggest that these coral species are not particularly sensitive to high pCO2 conditions but they are to ecologically relevant cobalt concentrations. Our study reveals that some reefs may be yet subjected to deleterious pollution levels, and even if no interaction between pCO2 levels and cobalt concentration has been found, it is likely that coral metabolism will be weakened if they are subjected to additional threats such as

  19. Responses of Two Scleractinian Corals to Cobalt Pollution and Ocean Acidification

    PubMed Central

    Biscéré, Tom; Rodolfo-Metalpa, Riccardo; Lorrain, Anne; Chauvaud, Laurent; Thébault, Julien; Clavier, Jacques; Houlbrèque, Fanny

    2015-01-01

    The effects of ocean acidification alone or in combination with warming on coral metabolism have been extensively investigated, whereas none of these studies consider that most coral reefs near shore are already impacted by other natural anthropogenic inputs such as metal pollution. It is likely that projected ocean acidification levels will aggravate coral reef health. We first investigated how ocean acidification interacts with one near shore locally abundant metal on the physiology of two major reef-building corals: Stylophora pistillata and Acropora muricata. Two pH levels (pHT 8.02; pCO2 366 μatm and pHT 7.75; pCO2 1140 μatm) and two cobalt concentrations (natural, 0.03 μg L-1 and polluted, 0.2 μg L-1) were tested during five weeks in aquaria. We found that, for both species, cobalt input decreased significantly their growth rates by 28% while it stimulated their photosystem II, with higher values of rETRmax (relative Electron Transport Rate). Elevated pCO2 levels acted differently on the coral rETRmax values and did not affect their growth rates. No consistent interaction was found between pCO2 levels and cobalt concentrations. We also measured in situ the effect of higher cobalt concentrations (1.06 ± 0.16 μg L-1) on A. muricata using benthic chamber experiments. At this elevated concentration, cobalt decreased simultaneously coral growth and photosynthetic rates, indicating that the toxic threshold for this pollutant has been reached for both host cells and zooxanthellae. Our results from both aquaria and in situ experiments, suggest that these coral species are not particularly sensitive to high pCO2 conditions but they are to ecologically relevant cobalt concentrations. Our study reveals that some reefs may be yet subjected to deleterious pollution levels, and even if no interaction between pCO2 levels and cobalt concentration has been found, it is likely that coral metabolism will be weakened if they are subjected to additional threats such as

  20. Synthesis and reactivity of a mononuclear non-haem cobalt(IV)-oxo complex

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Lee, Yong-Min; Tcho, Woon-Young; Tussupbayev, Samat; Kim, Seoung-Tae; Kim, Yujeong; Seo, Mi Sook; Cho, Kyung-Bin; Dede, Yavuz; Keegan, Brenna C.; Ogura, Takashi; Kim, Sun Hee; Ohta, Takehiro; Baik, Mu-Hyun; Ray, Kallol; Shearer, Jason; Nam, Wonwoo

    2017-03-01

    Terminal cobalt(IV)-oxo (CoIV-O) species have been implicated as key intermediates in various cobalt-mediated oxidation reactions. Herein we report the photocatalytic generation of a mononuclear non-haem [(13-TMC)CoIV(O)]2+ (2) by irradiating [CoII(13-TMC)(CF3SO3)]+ (1) in the presence of [RuII(bpy)3]2+, Na2S2O8, and water as an oxygen source. The intermediate 2 was also obtained by reacting 1 with an artificial oxidant (that is, iodosylbenzene) and characterized by various spectroscopic techniques. In particular, the resonance Raman spectrum of 2 reveals a diatomic Co-O vibration band at 770 cm-1, which provides the conclusive evidence for the presence of a terminal Co-O bond. In reactivity studies, 2 was shown to be a competent oxidant in an intermetal oxygen atom transfer, C-H bond activation and olefin epoxidation reactions. The present results lend strong credence to the intermediacy of CoIV-O species in cobalt-catalysed oxidation of organic substrates as well as in the catalytic oxidation of water that evolves molecular oxygen.

  1. Crystal structure of poly[[hexa­qua-1κ4 O,2κ2 O-bis­(μ3-pyridine-2,4-di­car­box­ylato-1κO 2:2κ2 N,O 2′;1′κO 4)cobalt(II)­strontium(II)] dihydrate

    PubMed Central

    Yu, Zhaojun; Jiang, Peng; Chen, Yanmei

    2015-01-01

    In the title polymeric complex, {[CoSr(C7H3NO4)2(H2O)6]·2H2O}n, the CoII ion, which is situated on a crystallographic centre of inversion, is six-coordinated by two O atoms and two N atoms from two pyridine-2,4-di­carboxyl­ate (pydc2−) ligands and two terminal water mol­ecules in a slightly distorted octa­hedral geometry, to form a trans-[Co(pydc)2(H2O)2]2− unit. The SrII ion, situated on a C 2 axis, is coordinated by four O atoms from four pydc2− ligands and four water mol­ecules. The coordination geometry of the SrII atom can be best described as a distorted dodeca­hedron. Each SrII ion bridges four [Co(pydc)2(H2O)2]2− units by four COO− groups of four pydc2− ligands to form a three-dimensional network structure. Two additional solvent water mol­ecules are observed in the crystal structure and are connected to the three-dimensional coordination polymer by O—H⋯O hydrogen bonds. Further intra- and intermolecular O—H⋯O hydrogen bonds consolidate the overall structure. PMID:26396869

  2. Sintered diamond compacts using metallic cobalt binders

    NASA Technical Reports Server (NTRS)

    Libby, W. F.; Katzman, H.

    1972-01-01

    Method is developed for sintering diamond powder which uses metallic cobalt as binder. Present samples show maximum microhardness of over 3000 kg/sq mm on Knoop scale. Material may be used as hard surface coating or may compete with cubic boron nitride as abrasive grain.

  3. Magnetization dynamics of cobalt grown on graphene

    SciTech Connect

    Berger, A. J.; White, S. P.; Adur, R.; Pu, Y.; Hammel, P. C.; Amamou, W.; Kawakami, R. K.

    2014-05-07

    Ferromagnetic resonance (FMR) spin pumping is a rapidly growing field which has demonstrated promising results in a variety of material systems. This technique utilizes the resonant precession of magnetization in a ferromagnet to inject spin into an adjacent non-magnetic material. Spin pumping into graphene is attractive on account of its exceptional spin transport properties. This article reports on FMR characterization of cobalt grown on chemical vapor deposition graphene and examines the validity of linewidth broadening as an indicator of spin pumping. In comparison to cobalt samples without graphene, direct contact cobalt-on-graphene exhibits increased FMR linewidth—an often used signature of spin pumping. Similar results are obtained in Co/MgO/graphene structures, where a 1 nm MgO layer acts as a tunnel barrier. However, magnetometry, magnetic force microscopy, and Kerr microscopy measurements demonstrate increased magnetic disorder in cobalt grown on graphene, perhaps due to changes in the growth process and an increase in defects. This magnetic disorder may account for the observed linewidth enhancement due to effects such as two-magnon scattering or mosaicity. As such, it is not possible to conclude successful spin injection into graphene from FMR linewidth measurements alone.

  4. Evidence of Formation of Superdense Nonmagnetic Cobalt

    PubMed Central

    Banu, Nasrin; Singh, Surendra; Satpati, B.; Roy, A.; Basu, S.; Chakraborty, P.; Movva, Hema C. P.; Lauter, V.; Dev, B. N.

    2017-01-01

    Because of the presence of 3d transition metals in the Earth’s core, magnetism of these materials in their dense phases has been a topic of great interest. Theory predicts a dense face-centred-cubic phase of cobalt, which would be nonmagnetic. However, this dense nonmagnetic cobalt has not yet been observed. Recent investigations in thin film polycrystalline materials have shown the formation of compressive stress, which can increase the density of materials. We have discovered the existence of ultrathin superdense nonmagnetic cobalt layers in a polycrystalline cobalt thin film. The densities of these layers are about 1.2–1.4 times the normal density of Co. This has been revealed by X-ray reflectometry experiments, and corroborated by polarized neutron reflectometry (PNR) experiments. Transmission electron microscopy provides further evidence. The magnetic depth profile, obtained by PNR, shows that the superdense Co layers near the top of the film and at the film-substrate interface are nonmagnetic. The major part of the Co film has the usual density and magnetic moment. These results indicate the possibility of existence of nonmagnetic Co in the earth’s core under high pressure. PMID:28157186

  5. Evidence of Formation of Superdense Nonmagnetic Cobalt

    NASA Astrophysics Data System (ADS)

    Banu, Nasrin; Singh, Surendra; Satpati, B.; Roy, A.; Basu, S.; Chakraborty, P.; Movva, Hema C. P.; Lauter, V.; Dev, B. N.

    2017-02-01

    Because of the presence of 3d transition metals in the Earth’s core, magnetism of these materials in their dense phases has been a topic of great interest. Theory predicts a dense face-centred-cubic phase of cobalt, which would be nonmagnetic. However, this dense nonmagnetic cobalt has not yet been observed. Recent investigations in thin film polycrystalline materials have shown the formation of compressive stress, which can increase the density of materials. We have discovered the existence of ultrathin superdense nonmagnetic cobalt layers in a polycrystalline cobalt thin film. The densities of these layers are about 1.2–1.4 times the normal density of Co. This has been revealed by X-ray reflectometry experiments, and corroborated by polarized neutron reflectometry (PNR) experiments. Transmission electron microscopy provides further evidence. The magnetic depth profile, obtained by PNR, shows that the superdense Co layers near the top of the film and at the film-substrate interface are nonmagnetic. The major part of the Co film has the usual density and magnetic moment. These results indicate the possibility of existence of nonmagnetic Co in the earth’s core under high pressure.

  6. Localized comedo formation after cobalt irradiation

    SciTech Connect

    Myskowski, P.L.; Safai, B.

    1981-10-01

    Following Cobalt-60 irradiation for a left frontotemporal tumor, a 61-year-old woman developed comedones on the forehead. These changes responded to conventional acne therapy with retinoic acid. Multiple acneigenic factors were implicated in the pathogenesis of her lesions.

  7. Hardfacing with cobalt and nickel alloys

    SciTech Connect

    Wu, J.B.C. ); Redman, J. , Los Angles, CA )

    1994-09-01

    The use of cobalt or nickel alloys for added wear resistance was initiated in the early 1900s with the development of the cobalt-chromium-tungsten family of alloys. The cobalt alloys were called the Stellite'' because of their bright, shiny, nontarnished appearance. Further development and characterization of this alloy system established its usage in unlubricated metal-to-metal contact or erosion by high-velocity fluid or solid particulate impingement. Initially, the alloys were used as solid castings but later were applied by welding to tougher or more ductile substrates, hence the birth of the hardfacing industry. Many of the original Stellite compositions are still in use, but many others, including the nickel and iron alloys, have been developed for special applications or for use by newer application procedures. Examining the microstructural features and wear properties of these families of hardfacing alloys can help in choosing the right alloy for the job. Various cobalt and nickel alloys, their available product forms and the corresponding hardfacing methods, are reviewed in this article.

  8. Water splitting: Taking cobalt in isolation

    NASA Astrophysics Data System (ADS)

    Wang, Aiqin; Zhang, Tao

    2016-01-01

    The sustainable production of hydrogen is key to the delivery of clean energy in a hydrogen economy; however, lower-cost alternatives to platinum electrocatalysts are needed. Now, isolated, earth-abundant cobalt atoms dispersed over nitrogen-doped graphene are shown to efficiently electrolyse water to generate hydrogen.

  9. Sol-gel entrapped cobalt complex

    SciTech Connect

    Lima, Omar J. de; Papacidero, Andrea T.; Rocha, Lucas A.; Sacco, Herica C.; Nassar, Eduardo J.; Ciuffi, Katia J.; Bueno, Luciano A.; Messaddeq, Younes; Ribeiro, Sidney J.L

    2003-03-15

    This work describes optimized conditions for preparation of a cobalt complex entrapped in alumina amorphous materials in the form of powder. The hybrid materials, CoNHG, were obtained by a nonhydrolytic sol-gel route through condensation of aluminum chloride with diisopropylether in the presence of cobalt chloride. The materials were calcined at various temperatures. The presence of cobalt entrapped in the alumina matrix is confirmed by ultraviolet visible spectroscopy. The materials have been characterized by X-ray diffraction (XRD), surface area analysis, thermogravimetric analysis (TGA), differential thermal analyses (DTA) and transmission electron microscopy (TEM). The prepared alumina matrix materials are amorphous, even after heat treatment up to 750 deg. C. The XRD, TGA/DTA and TEM data support the increase of sample crystallization with increasing temperature. The specific surface area, pore size and pore diameter changed as a function of the heat treatment temperature employed. Different heat treatment temperatures result in materials with different compositions and structures, and influence their catalytic activity. The entrapped cobalt materials calcined at 750 deg. C efficiently catalyzed the epoxidation of (Z)-cyclooctene using iodozylbenzene as the oxygen donor.

  10. Substrate selectivity in the low temperature atomic layer deposition of cobalt metal films from bis(1,4-di-tert-butyl-1,3-diazadienyl)cobalt and formic acid.

    PubMed

    Kerrigan, Marissa M; Klesko, Joseph P; Rupich, Sara M; Dezelah, Charles L; Kanjolia, Ravindra K; Chabal, Yves J; Winter, Charles H

    2017-02-07

    The initial stages of cobalt metal growth by atomic layer deposition are described using the precursors bis(1,4-di-tert-butyl-1,3-diazadienyl)cobalt and formic acid. Ruthenium, platinum, copper, Si(100), Si-H, SiO2, and carbon-doped oxide substrates were used with a growth temperature of 180 °C. On platinum and copper, plots of thickness versus number of growth cycles were linear between 25 and 250 cycles, with growth rates of 0.98 Å/cycle. By contrast, growth on ruthenium showed a delay of up to 250 cycles before a normal growth rate was obtained. No films were observed after 25 and 50 cycles. Between 100 and 150 cycles, a rapid growth rate of ∼1.6 Å/cycle was observed, which suggests that a chemical vapor deposition-like growth occurs until the ruthenium surface is covered with ∼10 nm of cobalt metal. Atomic force microscopy showed smooth, continuous cobalt metal films on platinum after 150 cycles, with an rms surface roughness of 0.6 nm. Films grown on copper gave rms surface roughnesses of 1.1-2.4 nm after 150 cycles. Films grown on ruthenium, platinum, and copper showed resistivities of <20 μΩ cm after 250 cycles and had values close to those of the uncoated substrates at ≤150 cycles. X-ray photoelectron spectroscopy of films grown with 150 cycles on a platinum substrate showed surface oxidation of the cobalt, with cobalt metal underneath. Analogous analysis of a film grown with 150 cycles on a copper substrate showed cobalt oxide throughout the film. No film growth was observed after 1000 cycles on Si(100), Si-H, and carbon-doped oxide substrates. Growth on thermal SiO2 substrates gave ∼35 nm thick layers of cobalt(ii) formate after ≥500 cycles. Inherently selective deposition of cobalt on metallic substrates over Si(100), Si-H, and carbon-doped oxide was observed from 160 °C to 200 °C. Particle deposition occurred on carbon-doped oxide substrates at 220 °C.

  11. Substrate selectivity in the low temperature atomic layer deposition of cobalt metal films from bis(1,4-di-tert-butyl-1,3-diazadienyl)cobalt and formic acid

    NASA Astrophysics Data System (ADS)

    Kerrigan, Marissa M.; Klesko, Joseph P.; Rupich, Sara M.; Dezelah, Charles L.; Kanjolia, Ravindra K.; Chabal, Yves J.; Winter, Charles H.

    2017-02-01

    The initial stages of cobalt metal growth by atomic layer deposition are described using the precursors bis(1,4-di-tert-butyl-1,3-diazadienyl)cobalt and formic acid. Ruthenium, platinum, copper, Si(100), Si-H, SiO2, and carbon-doped oxide substrates were used with a growth temperature of 180 °C. On platinum and copper, plots of thickness versus number of growth cycles were linear between 25 and 250 cycles, with growth rates of 0.98 Å/cycle. By contrast, growth on ruthenium showed a delay of up to 250 cycles before a normal growth rate was obtained. No films were observed after 25 and 50 cycles. Between 100 and 150 cycles, a rapid growth rate of ˜1.6 Å/cycle was observed, which suggests that a chemical vapor deposition-like growth occurs until the ruthenium surface is covered with ˜10 nm of cobalt metal. Atomic force microscopy showed smooth, continuous cobalt metal films on platinum after 150 cycles, with an rms surface roughness of 0.6 nm. Films grown on copper gave rms surface roughnesses of 1.1-2.4 nm after 150 cycles. Films grown on ruthenium, platinum, and copper showed resistivities of <20 μ Ω cm after 250 cycles and had values close to those of the uncoated substrates at ≤150 cycles. X-ray photoelectron spectroscopy of films grown with 150 cycles on a platinum substrate showed surface oxidation of the cobalt, with cobalt metal underneath. Analogous analysis of a film grown with 150 cycles on a copper substrate showed cobalt oxide throughout the film. No film growth was observed after 1000 cycles on Si(100), Si-H, and carbon-doped oxide substrates. Growth on thermal SiO2 substrates gave ˜35 nm thick layers of cobalt(ii) formate after ≥500 cycles. Inherently selective deposition of cobalt on metallic substrates over Si(100), Si-H, and carbon-doped oxide was observed from 160 °C to 200 °C. Particle deposition occurred on carbon-doped oxide substrates at 220 °C.

  12. Alternative synthesis of cobalt monophosphide@C core-shell nanocables for electrochemical hydrogen production

    NASA Astrophysics Data System (ADS)

    Wang, Chunde; Jiang, Jun; Zhou, Xiaoli; Wang, Wenliang; Zuo, Jian; Yang, Qing

    2015-07-01

    Cobalt monophosphide@C (CoP@C) core-shell nanocables are successfully synthesized via a one-step fast reaction of cobalt(II) acetylacetonate [Co(acac)2] and triphenyl phosphine (PPh3) in a sealed tube at 400 °C for 1 h. The electrocatalytic property of the CoP@C nanocables towards the hydrogen evolution reaction (HER, for the production of molecular hydrogen from water) has been investigated in the current work and it is found that the CoP@C nanocables exhibit a high electrochemical performance and excellent cycling stability. Moreover, investigations show that the carbon coating ensures a fast electron transport and effective restriction of corrosion during the catalytic process. We believe that the CoP@C nanocables would be promising candidates for electrochemical hydrogen production catalyst.

  13. Mössbauer study of cobalt and iron in the cyanobacterium (blue green alga)

    NASA Astrophysics Data System (ADS)

    Ambe, Shizuko

    1990-07-01

    Mössbauer emission and absorption studies have been performed on cobalt and iron in the cyanobacterium (blue-green alga). The Mössbauer spectrum of the cyanobacterium cultivated with57Co is decomposed into two doublets. The parameters of the major doublet are in good agreement with those of cyanocobalamin (vitamin B12) labeled with57Co. The other minor doublet has parameters close to those of Fe(II) coordinated with six nitrogen atoms. These suggest that cobalt is used for the biosynthesis of vitamin B12 or its analogs in the cyanobacterium. The spectra of the cyanobacterium grown with57Fe show that iron is in the high-spin trivalent state and possibly in the form of ferritin, iron storage protein.

  14. Catena-poly[[bis(1H-benzotriazole-kappaN3)cobalt(II)]-di-mu-tricyanomethanido-kappa2N:N'] and catena-poly[[bis(3,5-dimethyl-1H-pyrazole-kappaN2)manganese(II)]-di-mu-tricyanomethanido-kappa2N:N'].

    PubMed

    Shao, Ze-Huai; Luo, Jun; Cai, Rui-Fang; Zhou, Xi-Geng; Weng, Lin-Hong; Chen, Zhen-Xia

    2004-06-01

    Two new one-dimensional coordination polymers, viz. the title compounds, [Co[C(CN)(3)](2)(C(6)H(5)N(3))(2)](n), (I), and [Mn[C(CN)(3)](2)(C(5)H(8)N(2))(2)](n), (II), have been synthesized and characterized by X-ray diffraction. Both complexes consist of linear chains with double 1,5-tricyanomethanide bridges between neighbouring divalent metal ions. The Co and Mn atoms are located on centres of inversion. In (I), the coordination environment of the Co(II) atom is that of an elongated octahedron. The Co(II) atom is coordinated in the equatorial plane by four nitrile N atoms of four bridging tricyanomethanide ions, with Co-N distances of 2.106 (2) and 2.110 (2) A, and in the apical positions by two N atoms from the benzotriazole ligands, with a Co-N distance of 2.149 (2) A. The [Co[C(CN)(3)](2)(C(6)H(5)N(3))(2)] units form infinite chains extending along the a axis. These chains are crosslinked via a hydrogen bond between the uncoordinated nitrile N atom of a tricyanomethanide anion and the H atom on the uncoordinated N atom of a benzotriazole ligand from an adjacent chain, thus forming a three-dimensional network structure. In (II), the Mn(II) atom also adopts a slightly distorted octahedral geometry, with four nitrile N atoms of tricyanomethanide ligands [Mn-N = 2.226 (2) and 2.227 (2) A] in equatorial positions and two N atoms of the monodentate 3,5-dimethylpyrazole ligands [Mn-N = 2.231 (2) A] in the axial sites. In (II), one-dimensional polymeric chains extending along the b axis are formed, with tricyanomethanide anions acting as bidentate bridging ligands. A hydrogen bond between the uncoordinated nitrile N atom of the tricyanomethanide ligand and the H atom on the uncoordinated N atom of a 3,5-dimethylpyrazole group from a neighbouring chain links the molecule into a two-dimensional layered structure.

  15. Aging effects on cobalt availability in soils.

    PubMed

    Wendling, Laura A; Kirby, Jason K; McLaughlin, Michael J

    2009-08-01

    Aging processes in soils can significantly affect the potential biological availability of introduced metals via incorporation into crystal lattices, diffusion into micropores, or formation of metal precipitates on the surfaces of soil minerals. Over time, metals in contact with the soil solid phase are less freely exchangeable with the soil solution and, hence, less available to soil biota. In the present study, the effects of aging on the fate and behavior of added divalent cobalt (Co2+) in a range of soils with varying physicochemical characteristics was assessed using isotope-exchange techniques, chemical extraction, and plant growth. Following addition to soil, the Co2+ salt rapidly partitioned to the soil solid phase. Particularly in soils with neutral to alkaline pH, a large percentage of the surface-bound Co was fixed in forms no longer in equilibrium with soil solution cobalt through aging reactions. Using techniques commonly applied to estimate metal bioavailability in soil, the lability (E values), plant availability (L values), and extractability of added Co2+ salts with the mild chemical extractants calcium chloride (CaCl2) and ammonium nitrate (NH4NO3) were observed to markedly decrease with time, particularly in soils with high pH or those containing appreciable quantities of iron/ manganese oxyhydroxide minerals. Results indicated rapid partitioning of added Co2+ into isotopically nonexchangeable pools, with more than 60% of the aging occurring within 15 d in most soils. Soil pH was the primary factor controlling the rate of cobalt aging and extent of exchangeability in the soils examined. Understanding the influence of long-term aging on cobalt availability in soils is necessary to accurately assess the potential risk associated with cobalt contamination of soil environments.

  16. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung fibroblast cells

    SciTech Connect

    Smith, Leah J.; Holmes, Amie L.; Kandpal, Sanjeev Kumar; Mason, Michael D.; Zheng, Tongzhang; Wise, John Pierce

    2014-08-01

    Cobalt exposure is increasing as cobalt demand rises worldwide due to its use in enhancing rechargeable battery efficiency, super-alloys, and magnetic products. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in human lung cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble cobalt was more cytotoxic than particulate cobalt while particulate and soluble cobalt induced similar levels of genotoxicity. However, soluble cobalt induced cell cycle arrest indicated by the lack of metaphases at much lower intracellular cobalt concentrations compared to cobalt oxide. Accordingly, we investigated the role of particle internalization in cobalt oxide-induced toxicity and found that particle-cell contact was necessary to induce cytotoxicity and genotoxicity after cobalt exposure. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung fibroblasts, and solubility plays a key role in cobalt-induced lung toxicity. - Highlights: • Particulate and soluble cobalt are cytotoxic and genotoxic to human lung cells. • Soluble cobalt induces more cytotoxicity compared to particulate cobalt. • Soluble and particulate cobalt induce similar levels of genotoxicity. • Particle-cell contact is required for particulate cobalt-induced toxicity.

  17. Reducing the cobalt inventory in light water reactors

    SciTech Connect

    Ocken, H.

    1985-01-01

    Reducing the cobalt content of materials used in nuclear power plants is one approach to controlling the radiation fields responsible for occupational radiation exposure; corrosion of steam generator tubing is the primary source in pressurized water reactors (PWRs). Wear of the cobalt-base alloys used to hardface valves (especially feedwater regulator valves) and as pins and rollers in control blades are the primary boiling water reactor (BWR) sources. Routine valve maintenance can also be a significant source of cobalt. Wear, mechanical property, and corrosion measurements led to the selection of Nitronic-60/CFA and PH 13-8 Mo/Inconel X-750 as low-cobalt alloys for use as pin/roller combinations. These alloys are currently being tested in two commercial BWRs. Measurements show that Type 440C stainless steel wears less than the cobalt-base alloys in BWR feedwater regulator valves. Sliding wear tests performed at room temperature in simulated PWR water showed that Colmonoy 74 and 84, Deloro 40, and Vertx 4776 are attractive low-cobalt hardfacing alloys if the applied loads are less than or equal to103 MPa. The cobalt-base alloys performed best at high loads (207 MPa). Ongoing laboratory studies address the development and evaluation of cobalt-free iron-base hardfacing alloys and seek to improve the wear resistance of cobalt-base alloys by using lasers. Reducing cobalt impurity levels in core components that are periodically discharged should also help reduce radiation fields and disposal costs.

  18. Physical and electrochemical study of cobalt oxide nano- and microparticles

    SciTech Connect

    Alburquenque, D.; Vargas, E.; Denardin, J.C.; Escrig, J.; Marco, J.F.; Gautier, J.L.

    2014-07-01

    Cobalt oxide nanocrystals of size 17–21 nm were synthesized by a simple reaction between cobalt acetate (II) and dodecylamine. On the other hand, micrometric Co{sub 3}O{sub 4} was prepared using the ceramic method. The structural examination of these materials was performed using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM and HRTEM). XRD studies showed that the oxides were pure, well-crystallized, spinel cubic phases with a-cell parameter of 0.8049 nm and 0.8069 nm for the nano and micro-oxide, respectively. The average particle size was 19 nm (nano-oxide) and 1250 μm (micro-oxide). Morphological studies carried out by SEM and TEM analyses have shown the presence of octahedral particles in both cases. Bulk and surface properties investigated by X-ray photoelectron spectroscopy (XPS), point zero charge (pzc), FTIR and cyclic voltammetry indicated that there were no significant differences in the composition on both materials. The magnetic behavior of the samples was determined using a vibrating sample magnetometer. The compounds showed paramagnetic character and no coercivity and remanence in all cases. Galvanostatic measurements of electrodes formed with nanocrystals showed better performance than those built with micrometric particles. - Highlights: • Spinel Co{sub 3}O{sub 4} nanoparticles and microparticles with same structure but with different cell parameters, particle size and surface area were synthesized. • Oxide nanoparticles showed better electrochemical behavior than micrometric ones due to area effect.

  19. Cobalt-Catalysed Asymmetric Hydrovinylation of 1,3-Dienes

    PubMed Central

    Timsina, Yam N.; Sharma, Rakesh K.

    2015-01-01

    In the presence of bidentate 1,n-bis-diphenylphosphinoalkane-CoCl2 complexes {Cl2Co[P~P]} and Me3Al or methylaluminoxane, acyclic (E)-1,3-dienes react with ethylene (1 atmosphere) to give excellent yields of hydrovinylation products. The regioselectivity (1,4- or 1,2-addition) and the alkene configuration (E- or Z-) of the resulting product depend on the nature of the ligand and temperature at which the reaction is carried out. Cobalt(II)-complexes of 1,1-diphenylphosphinomethane and similar ligands with narrow bite angles give mostly 1,2-addition, retaining the E-geometry of the original diene. Complexes of most other ligands at low temperature (−40 °C) give almost exclusively a single branched product, (Z)-3-alkylhexa-1,4-diene, which arises from a 1,4-hydrovinylation reaction. A minor product is the linear adduct, a 5-alkyl-hexa-1,4-diene, also arising from a 1,4-addition of ethylene. As the temperature is increased, a higher proportion of the major 1,4-adduct appears as the (E)-isomer. The unexpectedly high selectivity seen in the Co-catalysed reaction as compared to the corresponding Ni-catalysed reaction can be rationalized by invoking the intermediacy of an η4-[(diene)[P~P]CoH]+-complex and its subsequent reactions. The enhanced reactivity of terminal E-1,3-dienes over the corresponding Z-dienes can also be explained on the basis of the ease of formation of this η4-complex in the former case. The lack of reactivity of the X2Co(dppb) (X = Cl, Br) complexes in the presence of Zn/ZnI2 makes the Me3Al-mediated reaction different from the previously reported hydroalkenylation of dienes. Electron-rich phospholanes, bis-oxazolines and N-heterocyclic carbenes appear to be poor ligands for the Co(II)-catalysed hydrovinylation of 1,3-dienes. An extensive survey of chiral ligands reveals that complexes of DIOP, BDDP and Josiphos ligands are quite effective for these reactions even at −45 °C and enantioselectivities in the range of 90–99 % ee can be realized

  20. Effects of cobalt precursor on pyrolyzed carbon-supported cobalt-polypyrrole as electrocatalyst toward oxygen reduction reaction

    PubMed Central

    2013-01-01

    A series of non-precious metal electrocatalysts, namely pyrolyzed carbon-supported cobalt-polypyrrole, Co-PPy-TsOH/C, are synthesized with various cobalt precursors, including cobalt acetate, cobalt nitrate, cobalt oxalate, and cobalt chloride. The catalytic performance towards oxygen reduction reaction (ORR) is comparatively investigated with electrochemical techniques of cyclic voltammogram, rotating disk electrode and rotating ring-disk electrode. The results are analyzed and discussed employing physiochemical techniques of X-ray diffraction, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma, elemental analysis, and extended X-ray absorption fine structure. It shows that the cobalt precursor plays an essential role on the synthesis process as well as microstructure and performance of the Co-PPy-TsOH/C catalysts towards ORR. Among the studied Co-PPy-TsOH/C catalysts, that prepared with cobalt acetate exhibits the best ORR performance. The crystallite/particle size of cobalt and its distribution as well as the graphitization degree of carbon in the catalyst greatly affects the catalytic performance of Co-PPy-TsOH/C towards ORR. Metallic cobalt is the main component in the active site in Co-PPy-TsOH/C for catalyzing ORR, but some other elements such as nitrogen are probably involved, too. PMID:24229351

  1. Azido- and chlorido-cobalt complex as carrier-prototypes for antitumoral prodrugs.

    PubMed

    Pires, Bianca M; Giacomin, Letícia C; Castro, Frederico A V; Cavalcanti, Amanda dos S; Pereira, Marcos D; Bortoluzzi, Adailton J; Faria, Roberto B; Scarpellini, Marciela

    2016-04-01

    Cobalt(III) complexes are well-suited systems for cytotoxic drug release under hypoxic conditions. Here, we investigate the effect of cytotoxic azide release by cobalt-containing carrier-prototypes for antitumoral prodrugs. In addition, we study the species formed after reduction of Co(3+) → Co(2+) in the proposed models for these prodrugs. Three new complexes, [Co(III)(L)(N3)2]BF4(1), [{Co(II)(L)(N3)}2](ClO4)2(2), and [Co(II)(L)Cl]PF6(3), L=[(bis(1-methylimidazol-2-yl)methyl)(2-(pyridyl-2-yl)ethyl)amine], were synthesized and studied by several spectroscopic, spectrometric, electrochemical, and crystallographic methods. Reactivity and spectroscopic data reveal that complex 1 is able to release N3(-) either after reduction with ascorbic acid, or by ambient light irradiation, in aqueous phosphate buffer (pH6.2, 7.0 and 7.4) and acetonitrile solutions. The antitumoral activities of compounds 1-3 were tested in normoxia on MCF-7 (human breast adenocarcinoma), PC-3 (human prostate) and A-549 (human lung adenocarcinoma epithelial) cell lines, after 24h of exposure. Either complexes or NaN3 presented IC50 values higher than 200 μM, showing lower cytotoxicity than the clinical standard antitumoral complex cisplatin, under the same conditions. Complexes 1-3 were also evaluated in hypoxia on A-549 and results indicate high IC50 data (>200 μM) after 24h of exposure. However, an increase of cancer cell susceptibility to 1 and 2 was observed at 300 μM. Regarding complex 3, no cytotoxic activity was observed in the same conditions. The data presented here indicate that the tridentate ligand L is able to stabilize both oxidation states of cobalt (+3 and +2). In addition, the cobalt(III) complex generates the low cytotoxic cobalt(II) species after reduction, which supports their use as as carrier prototypes for antitumoral prodrugs.

  2. Cobalt excretion in urine: results of a study on workers producing diamond grinding tools and on a control group.

    PubMed

    Mosconi, G; Bacis, M; Vitali, M T; Leghissa, P; Sabbioni, E

    1994-06-30

    A study was carried out on cobalt (Co) excretion in the urine of 12 workers exposed to known cobalt concentrations in the stone cutting diamond wheel production and in six volunteers: four of these were exposed in the same work environment for a whole workshift and the other two were exposed to cobalt in a cabin under experimental conditions. The kinetics of the urinary excretion was multiphase: (i) a first stage of rapid elimination (T 1/2' = 43.9 h); (ii) a second phase of slower elimination (T 1/2'' = 10 days); (iii) a longer period of retention, of the order of years, in subjects with higher exposure. In the control group (4 subjects), the excretion proved to be much faster in the first stage (T 1/2' = 20 h). The different behaviour of the two groups could be related to the different body burden, of cobalt and/or to the possibility of different kinetics induced by continuous exposure to the metal. Moreover, 3 weeks after the removal of the workers from exposure the urinary cobalt concentrations were not within the normal limits of CoU for the general population, (even for workers exposed to cobalt levels of the same order as the TLV). The increase of CoU concentrations in the first 3 h after the end of exposure, stresses the problem of when urine samples for biological monitoring of the workers should be collected. The present study confirms the utility of CoU in discriminating between exposed and non-exposed subjects as well as in assessing high and low level exposure.

  3. Reversible carbon-carbon bond formation induced by oxidation and reduction at a redox-active cobalt complex.

    PubMed

    Atienza, Crisita Carmen Hojilla; Milsmann, Carsten; Semproni, Scott P; Turner, Zoë R; Chirik, Paul J

    2013-05-06

    The electronic structure of the diamagnetic pyridine imine enamide cobalt dinitrogen complex, ((iPr)PIEA)CoN2 ((iPr)PIEA = 2-(2,6-(i)Pr2-C6H3N═CMe)-6-(2,6-(i)Pr2-C6H3NC═CH2)C5H3N), was determined and is best described as a low-spin cobalt(II) complex antiferromagnetically coupled to an imine radical anion. Addition of potential radical sources such as NO, PhSSPh, or Ph3Cl resulted in C-C coupling at the enamide positions to form bimetallic cobalt compounds. Treatment with the smaller halocarbon, PhCH2Cl, again induced C-C coupling to form a bimetallic bis(imino)pyridine cobalt chloride product but also yielded a monomeric cobalt chloride product where the benzyl group added to the enamide carbon. Similar cooperative metal-ligand addition was observed upon treatment of ((iPr)PIEA)CoN2 with CH2═CHCH2Br, which resulted in allylation of the enamide carbon. Reduction of Coupled-((iPr)PDI)CoCl (Coupled-((iPr)PDI)CoCl = [2-(2,6-(i)Pr2-C6H3N═CMe)-C5H3N-6-(2,6-(i)Pr2-C6H3N═CCH2-)CoCl]2) with NaBEt3H led to quantitative formation of ((iPr)PIEA)CoN2, demonstrating the reversibility of the C-C bond forming reactions. The electronic structures of each of the bimetallic cobalt products were also elucidated by a combination of experimental and computational methods.

  4. Pulsed Laser Deposition of Nanoporous Cobalt Thin Films

    PubMed Central

    Jin, Chunming; Nori, Sudhakar; Wei, Wei; Aggarwal, Ravi; Kumar, Dhananjay; Narayan, Roger J.

    2013-01-01

    Nanoporous cobalt thin films were deposited on anodized aluminum oxide (AAO) membranes at room temperature using pulsed laser deposition. Scanning electron microscopy demonstrated that the nanoporous cobalt thin films retained the monodisperse pore size and high porosity of the anodized aluminum oxide substrates. Temperature- and field-dependent magnetic data obtained between 10 K and 350 K showed large hysteresis behavior in these materials. The increase of coercivity values was larger for nanoporous cobalt thin films than for multilayered cobalt/alumina thin films. The average diameter of the cobalt nanograins in the nanoporous cobalt thin films was estimated to be ~5 nm for blocking temperatures near room temperature. These results suggest that pulsed laser deposition may be used to fabricate nanoporous magnetic materials with unusual properties for biosensing, drug delivery, data storage, and other technological applications. PMID:19198344

  5. Cobalt metabolism and toxicology--a brief update.

    PubMed

    Simonsen, Lars Ole; Harbak, Henrik; Bennekou, Poul

    2012-08-15

    Cobalt metabolism and toxicology are summarized. The biological functions of cobalt are updated in the light of recent understanding of cobalt interference with the sensing in almost all animal cells of oxygen deficiency (hypoxia). Cobalt (Co(2+)) stabilizes the transcriptional activator hypoxia-inducible factor (HIF) and thus mimics hypoxia and stimulates erythropoietin (Epo) production, but probably also by the same mechanism induces a coordinated up-regulation of a number of adaptive responses to hypoxia, many with potential carcinogenic effects. This means on the other hand that cobalt (Co(2+)) also may have beneficial effects under conditions of tissue hypoxia, and possibly can represent an alternative to hypoxic preconditioning. Cobalt is acutely toxic in larger doses, and in mammalian in vitro test systems cobalt ions and cobalt metal are cytotoxic and induce apoptosis and at higher concentrations necrosis with inflammatory response. Cobalt metal and salts are also genotoxic, mainly caused by oxidative DNA damage by reactive oxygen species, perhaps combined with inhibition of DNA repair. Of note, the evidence for carcinogenicity of cobalt metal and cobalt sulfate is considered sufficient in experimental animals, but is as yet considered inadequate in humans. Interestingly, some of the toxic effects of cobalt (Co(2+)) have recently been proposed to be due to putative inhibition of Ca(2+) entry and Ca(2+)-signaling and competition with Ca(2+) for intracellular Ca(2+)-binding proteins. The tissue partitioning of cobalt (Co(2+)) and its time-dependence after administration of a single dose have been studied in man, but mainly in laboratory animals. Cobalt is accumulated primarily in liver, kidney, pancreas, and heart, with the relative content in skeleton and skeletal muscle increasing with time after cobalt administration. In man the renal excretion is initially rapid but decreasing over the first days, followed by a second, slow phase lasting several weeks

  6. 21 CFR 189.120 - Cobaltous salts and its derivatives.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Cobaltous salts and its derivatives. 189.120... Generally Prohibited From Direct Addition or Use as Human Food § 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4H6O4, CoCl2, and CoSO4.They have been used in...

  7. 21 CFR 189.120 - Cobaltous salts and its derivatives.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Cobaltous salts and its derivatives. 189.120... Generally Prohibited From Direct Addition or Use as Human Food § 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4H6O4, CoCl2, and CoSO4.They have been used in...

  8. 21 CFR 189.120 - Cobaltous salts and its derivatives.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Cobaltous salts and its derivatives. 189.120... Generally Prohibited From Direct Addition or Use as Human Food § 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4H6O4, CoCl2, and CoSO4.They have been used in...

  9. 21 CFR 189.120 - Cobaltous salts and its derivatives.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Cobaltous salts and its derivatives. 189.120... Generally Prohibited From Direct Addition or Use as Human Food § 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the chemicals, CoC4H6O4, CoCl2, and CoSO4.They have been used in...

  10. Creep-fatigue of low cobalt superalloys

    NASA Technical Reports Server (NTRS)

    Halford, G. R.

    1982-01-01

    Testing for the low cycle fatigue and creep fatigue resistance of superalloys containing reduced amounts of cobalt is described. The test matrix employed involves a single high temperature appropriate for each alloy. A single total strain range, again appropriate to each alloy, is used in conducting strain controlled, low cycle, creep fatigue tests. The total strain range is based upon the level of straining that results in about 10,000 cycles to failure in a high frequency (0.5 Hz) continuous strain-cycling fatigue test. No creep is expected to occur in such a test. To bracket the influence of creep on the cyclic strain resistance, strain hold time tests with ore minute hold periods are introduced. One test per composition is conducted with the hold period in tension only, one in compression only, and one in both tension and compression. The test temperatures, alloys, and their cobalt compositions that are under study are given.

  11. Gamma europium- and cobalt-sources

    SciTech Connect

    Klochkov, E.P.; Risovany, V.D.; Ponomarenko, B.V.

    1993-12-31

    The double-purpose control rods of nuclear reactors were made in which the inserts containing cobalt and europium oxide with natural {sup 151}Eu and {sup 153}Eu content were used as an absorbing core. The mass content of europium oxide is to exceed 15% to provide for a necessary reactivity. Cobalt and europium radionuclides were shown to be accumulated during the reactor operation allowing the inserts to be used as gamma sources after unloading of control rods at large commercial plants for radiation processing of different materials. Shape, geometry and composition of inserts were optimized allowing their specific activity to be obtained above 2 x 10 Bq/g (about 60 Ci/g). The spectral activity and radiation resistance of gamma sources were studied.

  12. Cobalt contraction of vascular smooth muscle

    SciTech Connect

    Dominiczak, A.; Clyde, E.; Bohr, D. )

    1991-03-11

    Although it has been reported that cobalt causes contraction of vascular smooth muscle, the mechanism responsible for this contraction has not been defined. The authors studied these contractions in rat aortic rings. Concentration-response studies indicated that the threshold for contraction was 10{sup {minus}8}M, maximum contraction occurred at 3 {times} 10{sup 7}M and relaxation began at 10{sup {minus}6}M. No contraction occurred in a calcium-free physiological salt solution and the contraction was not inhibited by H-7, a protein kinase C inhibitor. The authors conclude the cobalt in low concentrations causes contraction by activating calcium channels and that in high concentrations it causes relaxation by inactivating these same channels.

  13. Are cobaltates conventional? An ARPES viewpoint

    SciTech Connect

    Hasan, M.Z. . E-mail: mzhasan@Princeton.edu; Qian, D.; Foo, M.L.; Cava, R.J.

    2006-07-15

    Recently discovered class of cobaltate superconductors (Na{sub 0.3}CoO{sub 2}.nH{sub 2}O) is a novel realization of interacting quantum electron system in a triangular network with low-energy degrees of freedom. We employ angle-resolved photoemission spectroscopy to study the quasiparticle parameters in the parent superconductors. Results reveal a large hole-like Fermi surface generated by the crossing of heavy quasiparticles. The measured quasiparticle parameters collectively suggest two orders of magnitude departure from the conventional weak coupling (such as Al) Bardeen-Cooper-Schrieffer electron dynamics paradigm and unveils cobaltates as a rather hidden class of relatively high temperature superconductors. These parameters also form the basis for a microscopic Hamiltonian of the system.

  14. Selective electrochemical reduction of CO2 to CO with a cobalt chlorin complex adsorbed on multi-walled carbon nanotubes in water.

    PubMed

    Aoi, Shoko; Mase, Kentaro; Ohkubo, Kei; Fukuzumi, Shunichi

    2015-06-25

    Electrocatalytic reduction of CO2 occurred efficiently using a glassy carbon electrode modified with a cobalt(II) chlorin complex adsorbed on multi-walled carbon nanotubes at an applied potential of -1.1 V vs. NHE to yield CO with a Faradaic efficiency of 89% with hydrogen production accounting for the remaining 11% at pH 4.6.

  15. High-Spin Cobalt Hydrides for Catalysis

    SciTech Connect

    Holland, Patrick L.

    2013-08-29

    Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

  16. Cobalt Ions Improve the Strength of Epoxy Resins

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St. Clair, A. K.

    1986-01-01

    Technique developed for improving mechanical strength of epoxy resins by adding cobalt ions in form of tris(acetylacetonato)cobalt (III) complex. Solid cast disks prepared from cobalt ion-containing epoxy resins tested for flexural strength and stiffness. Incorporation of cobalt ions into epoxies increased flexural strength of resins by 10 to 95 percent. Suitable resins for this technique include any liquid or solid TGMDA resins. Improved epoxy formulation proves useful as composite matrix resin, adhesive, or casting resin for applications on commercial and advanced aircraft.

  17. Hot corrosion of low cobalt alloys

    NASA Technical Reports Server (NTRS)

    Stearns, C. A.

    1982-01-01

    The hot corrosion attack susceptibility of various alloys as a function of strategic materials content are investigated. Preliminary results were obtained for two commercial alloys, UDIMET 700 and Mar-M 247, that were modified by varying the cobalt content. For both alloys the cobalt content was reduced in steps to zero. Nickel content was increased accordingly to make up for the reduced cobalt but all other constituents were held constant. Wedge bar test samples were produced by casting. The hot corrosion test consisted of cyclically exposing samples to the high velocity flow of combustion products from an air-fuel burner fueled with jet A-1 and seeded with a sodium chloride aqueous solution. The flow velocity was Mach 0.5 and the sodium level was maintained at 0.5 ppm in terms of fuel plus air. The test cycle consisted of holding the test samples at 900 C for 1 hour followed by 3 minutes in which the sample could cool to room temperature in an ambient temperature air stream.

  18. Neuroprotective effect of cobalt chloride on hypobaric hypoxia-induced oxidative stress.

    PubMed

    Shrivastava, Kalpana; Shukla, Dhananjay; Bansal, Anju; Sairam, Mustoori; Banerjee, P K; Ilavazhagan, Govindaswamy

    2008-02-01

    Hypobaric hypoxia, characteristic of high altitude is known to increase the formation of reactive oxygen and nitrogen species (RONS), and decrease effectiveness of antioxidant enzymes. RONS are involved and may even play a causative role in high altitude related ailments. Brain is highly susceptible to hypoxic stress and is involved in physiological responses that follow. Exposure of rats to hypobaric hypoxia (7619 m) resulted in increased oxidation of lipids and proteins due to increased RONS and decreased reduced to oxidized glutathione (GSH/GSSG) ratio. Further, there was a significant increase in superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) levels. Increase in heme oxygenase 1 (HO-1) and heat shock protein 70 (HSP70) was also noticed along with metallothionein (MT) II and III. Administration of cobalt appreciably attenuated the RONS generation, oxidation of lipids and proteins and maintained GSH/GSSH ratio similar to that of control cells via induction of HO-1 and MT offering efficient neuroprotection. It can be concluded that cobalt reduces hypoxia oxidative stress by maintaining higher cellular HO-1 and MT levels via hypoxia inducible factor 1alpha (HIF-1alpha) signaling mechanisms. These findings provide a basis for possible use of cobalt for prevention of hypoxia-induced oxidative stress.

  19. Cobalt Complexes Containing Pendant Amines in the Second Coordination Sphere as Electrocatalysts for H2 Production

    SciTech Connect

    Fang, Ming; Wiedner, Eric S.; Dougherty, William G.; Kassel, W. S.; Liu, Tianbiao L.; DuBois, Daniel L.; Bullock, R. Morris

    2014-10-27

    A series of heteroleptic 17e- cobalt complexes, [CpCoII(PtBu2NPh2)](BF4), [CpC6F5CoII(PtBu2NPh2)](BF4), [CpC5F4NCoII(PtBu2NPh2)](BF4), [where P2tBuN2Ph = 1,5-diphenyl-3,7-di(tert-butyl)-1,5-diaza-3,7-diphosphacyclooctane, CpC6F5 = C5H4(C6F5), and CpC5F4N = C5H4(C5F4N)] were synthesized, and structures of all three were determined by X-ray crystallography. Electrochemical studies showed that the CoIII/II couple of [CpC5F4NCoII(PtBu2NPh2)]+ appears 250 mV positive of the CoIII/II couple of [CpCoII(PtBu2NPh2)] as a result of the strongly electron-withdrawing perfluorpyridyl substituent on the Cp ring. Reduction of these paramagnetic CoII complexes by KC8 led to the diamagnetic 18e- complexes CpICo(PtBu2NPh2), CpC6F5CoI(PtBu2NPh2), CpC5F4NCoI(PtBu2NPh2), which were also characterized by crystallography. Protonation of these neutral CoI complexes led to the cobalt hydrides [CpCoIII(PtBu2NPh2)H](BF4), [CpC6F5CoIII(PtBu2NPh2)H](BF4), and [CpC5F4NCoIII(PtBu2NPh2)H](BF4). The cobalt hydride with the most electron-withdrawing Cp ligand, [CpC5F4NCoIII(PtBu2NPh2)H]+ is an electrocatalyst for production of H2 using 4-MeOC6H4NH3BF4 (pKaMeCN = 11.86) with a turnover frequency of 350 s-1 and an overpotential of 0.75 V. Experimental measurement of thermochemical data provided further insights into the thermodynamics of H2 elimination. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

  20. Two cobalt(III) mono-dimethylglyoximates isolated from one reaction.

    PubMed

    Czapik, Agnieszka; Gdaniec, Maria

    2010-09-01

    The reaction of cobalt(II) nitrate hexahydrate with dimethylglyoxime (DMGH(2)) and 1,10-phenanthroline (phen) in a 1:1:2 molar ratio results in two Co(III) mono-dimethylglyoximates having two chelating phen ligands in cis positions and the Co(III) atom coordinated by six N atoms in a distorted octahedral coordination geometry. The isolated products differ in the deprotonation state of the DMGH(2) ligand. In [mu-hydrogen bis(N,N'-dioxidobutane-2,3-diimine)]tetrakis(1,10-phenanthroline)cobalt(III) trinitrate ethanol disolvate 1.87-hydrate, [Co(2)(C(4)H(6)N(2)O(2))(C(4)H(7)N(2)O(2))(C(12)H(8)N(2))(4)](NO(3))(3).2C(2)H(6)O.1.87H(2)O, (I), the C(2)-symmetric cation is formed with the coordination [Co(DMG)(phen)(2)](+) cations aggregating via a very strong O(-)...H(+)...O(-) hydrogen bond with an O...O distance of 2.409 (4) A. Crystals of (I) exhibit extensive disorder of the solvent molecules, the nitrate anions and one of the phen ligands. Compound (I) is a kinetic product, not isolated previously from similar systems, that transforms slowly into (N-hydroxy-N'-oxidobutane-2,3-diimine)bis(1,10-phenanthroline)cobalt(III) dinitrate ethanol monosolvate 0.4-hydrate, [Co(C(4)H(7)N(2)O(2))(C(12)H(8)N(2))(2)](NO(3))(2).C(2)H(6)O.0.40H(2)O, (II), with the DMGH(-) ligand hydrogen bonded to one of the nitrate anions. In (II), the solvent molecules and one of the nitrate anions are disordered.

  1. Oxidation of cobalt and manganese in seawater via a common microbially catalyzed pathway

    NASA Astrophysics Data System (ADS)

    Moffett, James W.; Ho, Jackson

    1996-09-01

    Cobalt and manganese uptake onto suspended particles was studied in waters collected from Waquoit Bay, Massachusetts and the upper water column of the Sargasso Sea using radiotracers, coupled with protocols used previously for Mn and Ce to distinguish biological and redox processes. Cobalt uptake onto suspended particles in Waquiot Bay was dominated by microbial oxidation. Moreover, there was a close relationship between Mn(II) and Co(II) oxidation, with Mn(II) specific rates approximately 7-10x faster. Oxidation of each element obeys Michaelis Menten kinetics, with identifical values of K m in a given sample and values of V max are 7× higher for Mn. Lineweaver-Burk plots, generated from saturation plots for Co and Mn oxidation at different Mn and Co concentrations, demonstrated competitive inhibition between Co and Mn. The results indicate that both elements are co-oxidized via the same microbial catalytic pathway, and that this is probably an important mechanism for the incorporation of Co into marine Mn oxides. In the Sargasso Sea, by contrast, Mn and Co uptake onto suspended particles were completely decoupled. Cobalt uptake was nonoxidative, biologically mediated, and enhanced by low to moderate levels of light. It is probably due primarily to uptake by phytoplankton. Manganese uptake was almost exclusively oxidative and was inhibited by light even at low intensities. The differences probably reflect a higher biological demand for Co in the Sargasso Sea (Co is a biologically essential element), where Co concentrations are low, and lower activity of Mn oxidizing bacteria. Results suggest that higher specific uptake rates of Co than Mn by phytoplankton in oceanic regimes could result in Co having a geochemistry intermediate between Mn and a more nutrient-type element, such as Zn. Nevertheless, Co and Mn cycling are expected to be closely coupled in regions of high microbial Mn oxidizing activity.

  2. Trace Element Status (Iron, Zinc, Copper, Chromium, Cobalt, and Nickel) in Iron-Deficiency Anaemia of Children under 3 Years

    PubMed Central

    Angelova, Maria Georgieva; Petkova-Marinova, Tsvetelina Valentinova; Pogorielov, Maksym Vladimirovich; Loboda, Andrii Nikolaevich; Nedkova-Kolarova, Vania Nedkova; Bozhinova, Atanaska Naumova

    2014-01-01

    Aim. To determine trace element status and aetiologic factors for development of trace elements deficiencies in children with iron-deficiency anaemia (IDA) aged 0 to 3 years. Contingent and Methods. 30 patients of the University Hospital, Pleven, Bulgaria—I group; 48 patients of the Sumy Regional Child's Clinical Hospital, Sumy, Ukraine—II group; 25 healthy controls were investigated. Serum concentrations of iron, zinc, copper, chromium, cobalt, and nickel were determined spectrophotometrically and by atomic absorption spectrophotometry. Results. Because the obtained serum levels of zinc, copper, and chromium were near the lower reference limits, I group was divided into IA and IB. In IA group, serum concentrations were lower than the reference values for 47%, 57%, and 73% of patients, respectively. In IB group, these were within the reference values. In II group, results for zinc, cobalt, and nickel were significantly lower (P < 0.05), and results for copper were significantly higher in comparison to controls. Conclusion. Low serum concentrations of zinc, copper, cobalt, and nickel were mainly due to inadequate dietary intake, malabsorption, and micronutrient interactions in both studied groups. Increased serum copper in II group was probably due to metabolic changes resulting from adaptations in IDA. Data can be used for developing a diagnostic algorithm for IDA. PMID:24839556

  3. The crystal structure of cobalt-substituted pseudoazurin from Alcaligenes faecalis.

    PubMed

    Gessmann, Renate; Kyvelidou, Christiana; Papadovasilaki, Maria; Petratos, Kyriacos

    2011-03-01

    The Cu(II) center at the active site of the blue copper protein pseudoazurin from Alcaligenes faecalis has been substituted by Co(II) via denaturing of the protein, chelation and removal of copper by EDTA and refolding of the apo-protein, followed by addition of an aqueous solution of CoCl(2). Sitting drop vapour diffusion experiments produced green hexagonal crystals, which belong to space group P6(5), with unit cell dimensions a = b = 50.03, c = 98.80 Å. Diffraction data, collected at 291 K on a copper rotating anode X-ray source, were phased by the anomalous signal of the cobalt atom. The structure was built automatically, fitted manually and subsequently refined to 1.86 Å resolution. The Co-substituted protein exhibits similar overall geometry to the native structure with copper. Cobalt binds more strongly to the axial Met86-Sδ and retains the tetrahedral arrangement with the four ligand atoms, His40-Nδ(1), Cys78-Sγ, His81-Nδ(1), and 86Met-Sδ, although the structure is less distorted than the native copper protein. The structure reported herein, is the first crystallographic structure of a Co(II)-substituted pseudoazurin.

  4. Uptake, localization, and speciation of cobalt in Triticum aestivum L. (wheat) and Lycopersicon esculentum M. (tomato).

    PubMed

    Collins, Richard N; Bakkaus, Estelle; Carrière, Marie; Khodja, Hicham; Proux, Olivier; Morel, Jean-Louis; Gouget, Barbara

    2010-04-15

    The root-to-shoot transfer, localization, and chemical speciation of Co were investigated in a monocotyledon (Triticum aestivum L., wheat) and a dicotyledon (Lycopersicon esculentum M., tomato) plant species grown in nutrient solution at low (5 muM) and high (20 muM) Co(II) concentrations. Cobalt was measured in the roots and shoots by inductively coupled plasma-mass spectrometry. X-ray absorption spectroscopy measurements were used to identify the chemical structure of Co within the plants and Co distribution in the leaves was determined by micro-PIXE (particle induced X-ray emission). Although the root-to-shoot transport was higher for tomato plants exposed to excess Co, both plants appeared as excluders. The oxidation state of Co(II) was not transformed by either plant in the roots or shoots and Co appeared to be present as Co(II) in a complex with carboxylate containing organic acids. Cobalt was also essentially located in the vascular system of both plant species indicating that neither responded to Co toxicity via sequestration in epidermal or trichome tissues as has been observed for other metals in metal hyperaccumulating plants.

  5. Cobalt and nickel macrocycles anchored to nanocrystalline titanium dioxide thin films: Sensitization, catalysis, and ligand association

    NASA Astrophysics Data System (ADS)

    Achey, Darren Craig

    The global demand for renewable, clean electricity and fuel has compelled efforts to utilize the immense power incident upon the Earth from the Sun. Photovoltaic systems could power the planet's electrical demands with only moderate efficiencies. However, mitigation of fossil fuels used for transportation and night-time electricity requires the storage of photon energy, for example, in the form of chemical bonds. Mesoporous, nanocrystalline TiO2 thin films provide a manifold for anchoring molecular species that absorb and utilize photons to catalyze fuel-generating reactions. The overarching theme of this thesis is to improve understanding of the semiconductor/molecule interface utilizing earth abundant first-row transition metal coordination compounds. Chapter 2 presents the non-ideal redox behavior of cobalt porphyrins anchored to semiconductor surfaces. Additionally, CoI porphyrins were utilized as photocatalysts for the 2e- reduction of organobromides to yield a CoIII-R intermediate. The cobalt-carbon bond of CoIII-R was photodissociated with visible light to yield Co II and R·. The organic radical dimerized to form R-R. Light excitation of CoI compounds was found to result in electron transfer to TiO2, Chapter 3. Cobalt porphyrins, phthalocyanines, glyoximes, and corrins were all observed to exhibit this behavior. Electron transfer was demonstrated to primarily occur via excitation into the large extinction coefficient metal-to-ligand charge transfer absorption bands of CoI complexes. Chapter 4 focuses on the unique coordination chemistry of cobalt porphyrins anchored to a TiO2 thin film. Notably, pyridine axially ligated a CoII porphyrin following excited-state electron transfer of the CoI porphyrin to the TiO2. The rate constant for recombination of an electron in the TiO2 with CoII was observed to decrease with increasing pyridine concentration, behavior attributed primarily to a negative shift of the CoII/I potential in the presence of pyridine. Finally

  6. Spectroscopic characterization and energy transfer process in cobalt and cobalt-iron co-doped ZnSe/ZnS crystals

    NASA Astrophysics Data System (ADS)

    Peppers, J.; Martyshkin, D. V.; Fedorov, V. V.; Mirov, S. B.

    2014-02-01

    Cobalt doped II-VI wide band semiconductors (e.g. ZnSe, ZnS, CdSe) are promising media for infrared (IR) laser applications. They could be utilized as effective passive Q-switches for cavities of Alexandrite as well as Nd and Er lasers operating over 0.7-0.8, 1.3-1.6, and ~2.8 μm spectral ranges. We report spectroscopic characterization of Co:ZnSe and Co:ZnS crystals. Absorption cross-sections were measured for 4A2(F) → 4T1(P), 4A2(F) → 4T1(F), and 4A2(F) → 4T2(F) transitions with maximum absorption at 768(726), 1615(1500), 2690(2740) nm for ZnSe(ZnS) crystals, respectively. The calculated absorption cross-sections of the above transitions were estimated to be 64(56)×1019, 7.5(7.8)×1019, and 0.52(0.49)×1019 cm2 for ZnSe(ZnS) crystal hosts. In addition to the above applications the cobalt ions could be utilized for excitation of Fe2+ ions via resonance energy transfer process. Tunable room temperature lasing of Fe 2+ doped binary and ternary chalcogenides has been successfully demonstrated over 3.5-6 μm spectral range. However, II-VI lasers based on Fe2+ active ions don't feature convenient commercially available pump sources (e.g. some Fe doped crystal hosts require pump wavelengths longer than 3 μm). Therefore, the process of energy transfer from Co2+ to Fe2+ ions could enable utilization of commercially available visible and near-infrared pump sources. We report a spectroscopic characterization of iron-cobalt co-doped ZnS and ZnSe crystals over 14-300K temperature range. Mid-IR laser oscillation at 3.9 μm(3.6 μm) via energy transfer in the Co:Fe:ZnSe (Co:Fe:ZnS) co-doped crystals was demonstrated under cobalt excitation at 4A2(F) → 4T1(P) (~0.7μm) and 4A2(F) → 4T1(F) (~1.56 μm) transitions.

  7. The role of cobalt on the creep of Waspaloy

    NASA Technical Reports Server (NTRS)

    Jarrett, R. N.; Chin, L.; Tien, J. K.

    1984-01-01

    Cobalt was systematically replaced with nickel in Waspaloy (which normally contains 13% Co) to determine the effects of cobalt on the creep behavior of this alloy. Effects of cobalt were found to be minimal on tensile strengths and microstructure. The creep resistance and the stress rupture resistance determined in the range from 704 to 760 C (1300 to 1400 C) were found to decrease as cobalt was removed from the standard alloy at all stresses and temperatures. Roughly a ten-fold drop in rupture life and a corresponding increase in minimum creep rate were found under all test conditions. Both the apparent creep activation energy and the matrix contribution to creep resistance were found to increase with cobalt. These creep effects are attributed to cobalt lowering the stacking fault energy of the alloy matrix. The creep resistance loss due to the removal of cobalt is shown to be restored by slightly increasing the gamma' volume fraction. Results are compared to a previous study on Udimet 700, a higher strength, higher gamma' volume fraction alloy with similar phase chemistry, in which cobalt did not affect creep resistance. An explanation for this difference in behavior based on interparticle spacing and cross-slip is presented.

  8. Comparative toxicity and carcinogenicity of soluble and insoluble cobalt compounds.

    PubMed

    Behl, Mamta; Stout, Matthew D; Herbert, Ronald A; Dill, Jeffrey A; Baker, Gregory L; Hayden, Barry K; Roycroft, Joseph H; Bucher, John R; Hooth, Michelle J

    2015-07-03

    Occupational exposure to cobalt is of widespread concern due to its use in a variety of industrial processes and the occurrence of occupational disease. Due to the lack of toxicity and carcinogenicity data following exposure to cobalt, and questions regarding bioavailability following exposure to different forms of cobalt, the NTP conducted two chronic inhalation exposure studies in rats and mice, one on soluble cobalt sulfate heptahydrate, and a more recent study on insoluble cobalt metal. Herein, we compare and contrast the toxicity profiles following whole-body inhalation exposures to these two forms of cobalt. In general, both forms were genotoxic in the Salmonella T98 strain in the absence of effects on micronuclei. The major sites of toxicity and carcinogenicity in both chronic inhalation studies were the respiratory tract in rats and mice, and the adrenal gland in rats. In addition, there were distinct sites of toxicity and carcinogenicity noted following exposure to cobalt metal. In rats, carcinogenicity was observed in the blood, and pancreas, and toxicity was observed in the testes of rats and mice. Taken together, these findings suggest that both forms of cobalt, soluble and insoluble, appear to be multi-site rodent carcinogens following inhalation exposure.

  9. Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation.

    PubMed

    Majtan, Tomas; Frerman, Frank E; Kraus, Jan P

    2011-04-01

    Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes including Fe-S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin IX (CoPPIX), which was incorporated into heme proteins including membrane-bound cytochromes and an expressed human cystathionine beta-synthase (CBS). The presence of CoPPIX in cytochromes inhibited their electron transport capacity and resulted in a substantially decreased respiration. Bacterial cells adapted to the increased cobalt concentration by inducing a modified mixed acid fermentative pathway under aerobiosis. We capitalized on the ability of E. coli to insert cobalt into PPIX to carry out an expression of CoPPIX-substituted heme proteins. The level of CoPPIX-substitution increased with the number of passages of cells in a cobalt-containing medium. This approach is an inexpensive method to prepare cobalt-substituted heme proteins compared to in vitro enzyme reconstitution or in vivo replacement using metalloporphyrin heme analogs and seems to be especially suitable for complex heme proteins with an additional coenzyme, such as human CBS.

  10. Potential for cobalt recovery from lateritic ores in Europe

    NASA Astrophysics Data System (ADS)

    Herrington, R.

    2012-04-01

    Cobalt is one of the 'critical metals' identified under the EU Raw Materials Initiative. Annually the global mine production of cobalt is around 55,000 tonnes,with Europe's industries consuming around 30% of that figure. Currently Europe produces around 27 tonnes of cobalt from mines in Finland although new capacity is planned. Co-bearing nickel laterite ores being mined in Greece, Macedonia and Kosovo where the cobalt is currently not being recovered (ores have typical analyses of 0.055% Co and >1% Ni,). These ores are currently treated directly in pyrometallurgical plants to recover the contained nickel and this process means there is no separate cobalt product produced. Hydrometallurgical treatment of mineralogically suitable laterite ores can recover the cobalt; for example Cuba recovers 3,500 tonnes of cobalt from its laterite mining operations, which are of a similar scale to the current European operations. Implementation of hydrometallurgical techniques is in its infancy in Europe with one deposit in Turkey planning to use atmospheric heap leaching to recover nickel and copper from oxide-dominated ores. More widespread implementation of these methods to mineralogically suitable ore types could unlock the highly significant undeveloped resources (with metal contents >0.04% Co and >1% Ni), which have been defined throughout the Balkans eastwards into Turkey. At a conservative estimate, this region has the potential to supply up to 30% of the EU cobalt requirements.

  11. Unconventional magnetisation texture in graphene/cobalt hybrids

    PubMed Central

    Vu, A. D.; Coraux, J.; Chen, G.; N’Diaye, A. T.; Schmid, A. K.; Rougemaille, N.

    2016-01-01

    Magnetic domain structure and spin-dependent reflectivity measurements on cobalt thin films intercalated at the graphene/Ir(111) interface are investigated using spin-polarised low-energy electron microscopy. We find that graphene-covered cobalt films have surprising magnetic properties. Vectorial imaging of magnetic domains reveals an unusually gradual thickness-dependent spin reorientation transition, in which magnetisation rotates from out-of-the-film plane to the in-plane direction by less than 10° per cobalt monolayer. During this transition, cobalt films have a meandering spin texture, characterised by a complex, three-dimensional, wavy magnetisation pattern. In addition, spectroscopy measurements suggest that the electronic band structure of the unoccupied states is essentially spin-independent already a few electron-Volts above the vacuum level. These properties strikingly differ from those of pristine cobalt films and could open new prospects in surface magnetism. PMID:27114039

  12. Cobalt ferrite nanoparticles under high pressure

    SciTech Connect

    Saccone, F. D.; Ferrari, S.; Grinblat, F.; Bilovol, V.; Errandonea, D.

    2015-08-21

    We report by the first time a high pressure X-ray diffraction and Raman spectroscopy study of cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles carried out at room temperature up to 17 GPa. In contrast with previous studies of nanoparticles, which proposed the transition pressure to be reduced from 20–27 GPa to 7.5–12.5 GPa (depending on particle size), we found that cobalt ferrite nanoparticles remain in the spinel structure up to the highest pressure covered by our experiments. In addition, we report the pressure dependence of the unit-cell parameter and Raman modes of the studied sample. We found that under quasi-hydrostatic conditions, the bulk modulus of the nanoparticles (B{sub 0} = 204 GPa) is considerably larger than the value previously reported for bulk CoFe{sub 2}O{sub 4} (B{sub 0} = 172 GPa). In addition, when the pressure medium becomes non-hydrostatic and deviatoric stresses affect the experiments, there is a noticeable decrease of the compressibility of the studied sample (B{sub 0} = 284 GPa). After decompression, the cobalt ferrite lattice parameter does not revert to its initial value, evidencing a unit cell contraction after pressure was removed. Finally, Raman spectroscopy provides information on the pressure dependence of all Raman-active modes and evidences that cation inversion is enhanced by pressure under non-hydrostatic conditions, being this effect not fully reversible.

  13. Binding of transition metal ions [cobalt, copper, nickel and zinc] with furanyl-, thiophenyl-, pyrrolyl-, salicylyl- and pyridyl-derived cephalexins as potent antibacterial agents.

    PubMed

    Chohan, Zahid H; Pervez, Humayun; Khan, Khalid Mohammed; Rauf, A; Supuran, Claudiu T

    2004-02-01

    A method is described for the preparation of novel cephalexin-derived furanyl-, thiophenyl-, pyrrolyl-, salicylyl- and pyridyl-containing compounds showing potent antibacterial activity. The binding of these newly synthesized antibacterial agents with metal ions such as cobalt(II), copper(II), nickel(II) and zinc(II) has been studied and their inhibitory properties against various bacterial species such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae are also reported. These results suggest that metal ions to possess an important role in the designing of metal-based antibacterials and that such complexes are more effective against infectious diseases compared to the uncomplexed drugs.

  14. Microemulsion-mediated synthesis of cobalt (pure fcc and hexagonal phases) and cobalt-nickel alloy nanoparticles.

    PubMed

    Ahmed, Jahangeer; Sharma, Shudhanshu; Ramanujachary, Kandalam V; Lofland, Samuel E; Ganguli, Ashok K

    2009-08-15

    By choosing appropriate microemulsion systems, hexagonal cobalt (Co) and cobalt-nickel (1:1) alloy nanoparticles have been obtained with cetyltrimethylammonium bromide as a cationic surfactant at 500 degrees C. This method thus stabilizes the hcp cobalt even at sizes (<10 nm) at which normally fcc cobalt is predicted to be stable. On annealing the hcp cobalt nanoparticles in H(2) at 700 degrees C we could transform them to fcc cobalt nanoparticles. Microscopy studies show the formation of spherical nanoparticles of hexagonal and cubic forms of cobalt and Co-Ni (1:1) alloy nanoparticles with the average size of 4, 8 and 20 nm, respectively. Electrochemical studies show that the catalytic property towards oxygen evolution is dependent on the applied voltage. At low voltage (less than 0.65 V) the Co (hexagonal) nanoparticles are superior to the alloy (Co-Ni) nanoparticles while above this voltage the alloy nanoparticles are more efficient catalysts. The nanoparticles of cobalt (hcp and fcc) and alloy (Co-Ni) nanoparticles show ferromagnetism. The saturation magnetization of Co-Ni nanoparticles is reduced compared to the bulk possibly due to surface oxidation.

  15. Low-Cobalt Powder-Metallurgy Superalloy

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1986-01-01

    Highly-stressed jet-engine parts made with less cobalt. Udimet 700* (or equivalent) is common nickel-based superalloy used in hot sections of jet engines for many years. This alloy, while normally used in wrought condition, also gas-atomized into prealloyed powder-metallurgy (PM) product. Product can be consolidated by hot isostatically pressing (HIPPM condition) and formed into parts such as turbine disk. Such jet-engine disks "see" both high stresses and temperatures to 1,400 degrees F (760 degrees C).

  16. Exafs data analysis of some cobalt complexes

    NASA Astrophysics Data System (ADS)

    Mishra, A.; Vibhute, Vishakha; Jain, Garima; Ninama, Samrath

    2012-05-01

    X-ray spectroscopy has assumed great significance with its increasing application in the different fields of physics like solid state physics, chemical physics, atomic physics, Plasma Physics and Astro physics etc.in present paper we obtained bond lengths of cobalt metal complexes using Levy's, LSS and Lytle methods and are compared by FEFFIT (Fitting of EXAFS by Fast Fourier Inverse Transform) method. Bond length basically known as radial distance between ligand and metal complexes. FEFFIT is computer program for calculating bond length obtained theoretical data of EXAFS.

  17. Cyanidotetra-kis-(trimethyl-phosphine)cobalt(I).

    PubMed

    Xu, Xiaofeng; Feng, Lei; Li, Xiaoyan

    2011-04-01

    The title compound, [Co(CN)(C(3)H(9)P)(4)], was obtained as a product of the reaction of [Co(PMe(3))(4)] with a molar equivalent of 2,6-difluoro-benzonitrile in diethyl ether. This compound is stable in the air for several hours, but rapidly decomposes at room temperature in solution. The cobalt(I) atom has s trigonal-bipyramidal coordination enviroment in which the cyano group and one of the PMe(3) groups are in the axial positions.

  18. Synthesis of lithium cobaltate in halide melts

    NASA Astrophysics Data System (ADS)

    Modenov, D. V.; Dokutovich, V. N.; Khokhlov, V. A.; Antonov, B. D.; Kochedykov, V. A.; Zakir'yanova, I. D.

    2013-02-01

    A new method for the synthesis of lithium cobaltate LiCoo2 in salt melts is proposed and tested. The method is based on the oxidation of halide ions with molecular oxygen in Li X-CoCl2 mixtures ( X = Cl, Br, I). The chemical and phase compositions of the prepared powders and the crystal structure of the synthesized compound are studied by Fourier transform infrared spectroscopy and X-ray diffraction analysis. The average size of LiCoO2 crystallites is estimated from the X-ray diffraction data.

  19. Nitrogen oxides storage catalysts containing cobalt

    DOEpatents

    Lauterbach, Jochen; Snively, Christopher M.; Vijay, Rohit; Hendershot, Reed; Feist, Ben

    2010-10-12

    Nitrogen oxides (NO.sub.x) storage catalysts comprising cobalt and barium with a lean NO.sub.x storage ratio of 1.3 or greater. The NO.sub.x storage catalysts can be used to reduce NO.sub.x emissions from diesel or gas combustion engines by contacting the catalysts with the exhaust gas from the engines. The NO.sub.x storage catalysts can be one of the active components of a catalytic converter, which is used to treat exhaust gas from such engines.

  20. Hot Corrosion of Cobalt-Base Alloys

    DTIC Science & Technology

    1975-06-01

    Cast Alloys : NASA VIA, B-1900, 713C and 738X", Report NASA TN D-7682, Lewis Research Center, Cleveland, Ohio, August 1974. 36. Giggins, C.S. and...resistance of cobalt-base and nickel-base alloys . The contract was accomplished under the technical direction of Dr. H. C. Graham of the Aerospace Research...Interpretation of Results 3. SODIUM SULFATE INDUCED HOT CORROSION OF Co-25Al AND Co-35Cr ALLOYS a. Introduction b. Experimental Co-25Al c. Experimental

  1. The Cytotoxicity and Genotoxicity of Particulate and Soluble Cobalt in Human Urothelial Cells.

    PubMed

    Speer, Rachel M; The, Therry; Xie, Hong; Liou, Louis; Adam, Rosalyn M; Wise, John Pierce

    2017-03-21

    Cobalt use is increasing particularly due to its use as one of the primary metals in cobalt-chromium-molybdenum (CoCrMo) metal-on-metal prosthetics. CoCrMo is a high-strength, wear-resistant alloy with reduced risk for prosthetic loosening and device fracture. More than 500,000 people receive hip implants each year in the USA which puts them at potential risk for exposure to metal ions and particles released by the prosthetic implants. Data show cobalt ions released from prosthetics reach the bloodstream and accumulate in the bladder. As patients with failed hip implants show increased urinary and blood cobalt levels, no studies have considered the effects of cobalt on human urothelial cells. Accordingly, we investigated the cytotoxic and genotoxic effects of particulate and soluble cobalt in urothelial cells. Exposure to both particulate and soluble cobalt resulted in a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ions. Based on intracellular cobalt ion levels, we found, when compared to particulate cobalt, soluble cobalt was more cytotoxic, but induced similar levels of genotoxicity. Interestingly, at similar intracellular cobalt ion concentrations, soluble cobalt induced cell cycle arrest indicated by a lack of metaphases not observed after particulate cobalt treatment. These data indicate that cobalt compounds are cytotoxic and genotoxic to human urothelial cells and solubility may play a key role in cobalt-induced toxicity.

  2. Comparison of supplemental cobalt form on fibre digestion and cobalamin concentrations in cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cobalt is essential for rumen microbial metabolism to synthesize methane, acetate and methionine. It also serves as a structural component of vitamin B12, which functions as a coenzyme in energy metabolism. A study was conducted to determine if cobalt form (cobalt carbonate vs cobalt glucoheptonate...

  3. Synthesis and Electrochemical Studies of Cobalt(III) Monohydride Complexes Containing Pendant Amines

    SciTech Connect

    Wiedner, Eric S.; Roberts, John A.; Dougherty, William G.; Kassel, W. S.; DuBois, Daniel L.; Bullock, R. Morris

    2013-08-14

    Two new tetraphosphine ligands, PnC-PPh22NPh2 (1,5-diphenyl-3,7-bis((diphenylphosphino)alkyl)-1,5-diaza-3,7-diphosphacyclooctane; alkyl = (CH2)2, n = 2 (L2); (CH2)3, n = 3 (L3)), have been synthesized. Coordination of these ligands to cobalt affords the complexes [CoII(L2)(CH3CN)]2+ and [CoII(L3)(CH3CN)]2+, which are reduced with KC8 to afford [CoI(L2)(CH3CN)]1+ and [CoI(L3)(CH3CN)]1+. Protonation of the CoI complexes affords [HCoIII(L2)(CH3CN)]2+ and [HCoIII(L3)(CH3CN)]2+. Reduction of HCoIII results in formation of the analogous CoI complex through H-Co bond cleavage. Under voltammetric conditions, the reduced cobalt hydride reacts rapidly with a protic solvent impurity to generate H2 in a monometallic process involving two electrons per cobalt. In contrast, under bulk electrolysis conditions, H2 formation requires only one reducing equivalent per [HCoIII(L2)(CH3CN)]2+, indicating a bimetallic route wherein two cobalt hydride complexes react to form two equiv [CoI(L2)(CH3CN)]1+ and one equiv H2. The cyclic voltammetry of [HCoIII(L2)(CH3CN)]2+, analyzed using digital simulation, is consistent with an ErCrEr reduction mechanism involving reversible acetonitrile dissociation from [HCoII(L2)(CH3CN)]1+. We thank the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences, for support of the initial parts of this study. Current work is supported by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific

  4. Serum levels of zinc, copper, iron, cobalt, magnesium, and selenium elements in children diagnosed with Giardia intestinalis and Enterobiosis vermicularis in Hatay, Turkey.

    PubMed

    Culha, Gülnaz; Sangün, Mustafa Kemal

    2007-07-01

    The intestinal parasites are noted to be an important health problem in Turkey as similarly reported in the globe. The aim of this study was to investigate the changes in total content of essential elements, namely, zinc, iron, copper, cobalt, magnesium, and selenium, in children infected with intestinal parasites aged between 6 and 12 years inhabiting in Hatay Province, Turkey. These essential elements were measured in the children/patient who was positive for intestinal parasites, Giardia intestinalis and Enterobius vermicularis. Scores were obtained from the positive study group (SG), and their age matched the healthy children control group (CG). Serological levels of zinc, iron, copper, cobalt, magnesium, and selenium were analyzed by Varian Liberty Series II inductively coupled plasma atomic emission spectrometer (ICP-AES). The mean magnesium concentrations were found to be statistically different at 95% confidence interval level between study groups. As a result of this study, selenium was found to be uncorrelated with all other elements examined; whereas, copper was observed to have statistically significant correlations with cobalt, magnesium, and zinc. In addition, cobalt-magnesium, cobalt-zinc, and magnesium-zinc metal pairs were found to have statistically significant correlations based on study findings.

  5. Surfactant-cobalt(III) complexes: The impact of hydrophobicity on interaction with HSA and DNA - insights from experimental and theoretical approach.

    PubMed

    Veeralakshmi, Selvakumar; Sabapathi, Gopal; Nehru, Selvan; Venuvanalingam, Ponnambalam; Arunachalam, Sankaralingam

    2017-02-16

    To develop surfactant-based metallodrugs, it is very important to know about their hydrophobicity, micelle forming capacity, their interaction with biomacromolecules such as proteins and nucleic acids, and biological activities. Here, diethylenetriamine (dien) and tetradecylamine ligand (TA) based surfactant-cobalt(III) complexes with single chain domain, [Co(dien)(TA)Cl2]ClO4 (1) and double chain domain [Co(dien)(TA)2Cl](ClO4)2 (2) were chosen to study the effect of hydrophobicity on the interaction with human serum albumin and calf thymus DNA. The obtained results showed that (i) single chain surfactant-cobalt(III) complex (1) interact with HSA and DNA via electrostatic interaction and groove binding, respectively; (ii) double chain surfactant-cobalt(III) complex (2) interact with HSA and DNA via hydrophobic interaction and partial intercalation, respectively, due to the play of hydrophobicity by single and double chain domains. Further it is noted that, double chain surfactant-cobalt(III) complex interact strongly with HSA and DNA, compared single chain surfactant-cobalt(III) complex due to their more hydrophobicity nature. DFT and molecular docking studies offer insights into the mechanism and mode of binding towards the molecular target CT-DNA and HSA. Hence, the present findings will create new avenue towards the use of hydrophobic metallodrugs for various therapeutic applications.

  6. C(sp(2))-H Borylation of Fluorinated Arenes Using an Air-Stable Cobalt Precatalyst: Electronically Enhanced Site Selectivity Enables Synthetic Opportunities.

    PubMed

    Obligacion, Jennifer V; Bezdek, Máté J; Chirik, Paul J

    2017-02-22

    Cobalt catalysts with electronically enhanced site selectivity have been developed, as evidenced by the high ortho-to-fluorine selectivity observed in the C(sp(2))-H borylation of fluorinated arenes. Both the air-sensitive cobalt(III) dihydride boryl 4-Me-((iPr)PNP)Co(H)2BPin (1) and the air-stable cobalt(II) bis(pivalate) 4-Me-((iPr)PNP)Co(O2C(t)Bu)2 (2) compounds were effective and exhibited broad functional group tolerance across a wide range of fluoroarenes containing electronically diverse functional groups, regardless of the substitution pattern on the arene. The electronically enhanced ortho-to-fluorine selectivity observed with the cobalt catalysts was maintained in the presence of a benzylic dimethylamine and hydrosilanes, overriding the established directing-group effects observed with precious-metal catalysts. The synthetically useful selectivity observed with cobalt was applied to an efficient synthesis of the anti-inflammatory drug flurbiprofen.

  7. Siderophore-promoted Dissolution of Cobalt from Hydroxide Minerals

    SciTech Connect

    Bi, Y.; Hesterberg, D; Duckworth, O

    2010-01-01

    Recent research has revealed that siderophores, a class of biogenic ligands with high affinities for Fe(III), can also strongly complex Co(III), an element essential to the normal metabolic function of microbes and animals. This study was conducted to quantify the rates and identify the products and mechanisms of the siderophore-promoted dissolution of Co from synthetic Co-bearing minerals. The dissolution reactions of heterogenite (CoOOH) and four Co-substituted goethites (Co-FeOOH) containing different Co concentrations were investigated in the presence of a trihydroxamate siderophore, desferrioxamine B (DFOB), using batch and flow-through experiments. Results showed that DFOB-promoted dissolution of Co from Co-bearing minerals may occur via pH-dependent ligand-promoted or reductive dissolution mechanisms. For heterogenite, ligand-promoted dissolution was the dominant pathway at neutral to alkaline pH, while production of dissolved Co(II) for pH <6. It was not possible from our data to decouple the separate contributions of homogenous and heterogeneous reduction reactions to the aqueous Co(II) pool. Cobalt substitution in Co-substituted goethite, possibly caused by distortion of goethite structure and increased lattice strain, resulted in enhanced total dissolution rates of both Co and Fe. The DFOB-promoted dissolution rates of Co-bearing minerals, coupled with the high affinity of Co(III) for DFOB, suggest that siderophores may be effective for increasing Co solubility, and thus possibly Co bioavailability. The results also suggest that siderophores may contribute to the mobilization of radioactive {sup 60}Co from Co-bearing mineral phases through mineral weathering and dissolution processes.

  8. Siderophore-promoted dissolution of cobalt from hydroxide minerals

    NASA Astrophysics Data System (ADS)

    Bi, Yuqiang; Hesterberg, Dean L.; Duckworth, Owen W.

    2010-05-01

    Recent research has revealed that siderophores, a class of biogenic ligands with high affinities for Fe(III), can also strongly complex Co(III), an element essential to the normal metabolic function of microbes and animals. This study was conducted to quantify the rates and identify the products and mechanisms of the siderophore-promoted dissolution of Co from synthetic Co-bearing minerals. The dissolution reactions of heterogenite (CoOOH) and four Co-substituted goethites (Co-FeOOH) containing different Co concentrations were investigated in the presence of a trihydroxamate siderophore, desferrioxamine B (DFOB), using batch and flow-through experiments. Results showed that DFOB-promoted dissolution of Co from Co-bearing minerals may occur via pH-dependent ligand-promoted or reductive dissolution mechanisms. For heterogenite, ligand-promoted dissolution was the dominant pathway at neutral to alkaline pH, while production of dissolved Co(II) for pH <6. It was not possible from our data to decouple the separate contributions of homogenous and heterogeneous reduction reactions to the aqueous Co(II) pool. Cobalt substitution in Co-substituted goethite, possibly caused by distortion of goethite structure and increased lattice strain, resulted in enhanced total dissolution rates of both Co and Fe. The DFOB-promoted dissolution rates of Co-bearing minerals, coupled with the high affinity of Co(III) for DFOB, suggest that siderophores may be effective for increasing Co solubility, and thus possibly Co bioavailability. The results also suggest that siderophores may contribute to the mobilization of radioactive 60Co from Co-bearing mineral phases through mineral weathering and dissolution processes.

  9. Cobalt triggers necrotic cell death and atrophy in skeletal C2C12 myotubes

    SciTech Connect

    Rovetta, Francesca; Stacchiotti, Alessandra; Faggi, Fiorella; Catalani, Simona; Apostoli, Pietro; Fanzani, Alessandro; Aleo, Maria Francesca

    2013-09-01

    Severe poisoning has recently been diagnosed in humans having hip implants composed of cobalt–chrome alloys due to the release of particulate wear debris on polyethylene and ceramic implants which stimulates macrophagic infiltration and destroys bone and soft tissue, leading to neurological, sensorial and muscular impairments. Consistent with this premise, in this study, we focused on the mechanisms underlying the toxicity of Co(II) ions on skeletal muscle using mouse skeletal C2C12 myotubes as an in vitro model. As detected using propidium iodide incorporation, increasing CoCl{sub 2} doses (from 5 to 200 μM) affected the viability of C2C12 myotubes, mainly by cell necrosis, which was attenuated by necrostatin-1, an inhibitor of the necroptotic branch of the death domain receptor signaling pathway. On the other hand, apoptosis was hardly detectable as supported by the lack of caspase-3 and -8 activation, the latter resulting in only faint activation after exposure to higher CoCl{sub 2} doses for prolonged time points. Furthermore, CoCl{sub 2} treatment resulted in atrophy of the C2C12 myotubes which was characterized by the increased expression of HSP25 and GRP94 stress proteins and other typical 'pro-atrophic molecular hallmarks, such as early activation of the NF-kB pathway and down-regulation of AKT phosphorylation, followed by the activation of the proteasome and autophagy systems. Overall, these results suggested that cobalt may impact skeletal muscle homeostasis as an inducer of cell necrosis and myofiber atrophy. - Highlights: • The effects of cobalt on muscle myofibers in vitro were investigated. • Cobalt treatment mainly causes cell necrosis in skeletal C2C12 myotubes. • Cobalt impacts the PI3K/AKT and NFkB pathways and induces cell stress markers. • Cobalt induces atrophy of C2C12 myotubes through the activation of proteasome and autophagy systems. • Co treatment triggers NF-kB and PI3K/AKT pathways in C2C12 myotubes.

  10. Cataractogenesis after Cobalt-60 eye plaque radiotherapy

    SciTech Connect

    Kleineidam, M.; Augsburger, J.J. ); Hernandez, C.; Glennon, P.; Brady, L.W. )

    1993-07-15

    This study was designed to estimate the actuarial incidence of typical postirradiation cataracts and to identify prognostic factors related to their development in melanoma-containing eyes treated by Cobalt-60 plaque radiotherapy. A special interest was the impact of calculated radiation dose and dose-rate to the lens. The authors evaluated the actuarial occurrence of post-irradiation cataract in 365 patients with primary posterior uveal melanoma treated by Cobalt-60 plaque radiotherapy between 1976 and 1986. Only 22% (S.E. = 4.6%) of the patients who received a total dose of 6 to 20 Gy at the center of the lens developed a visually significant cataract attributable to the radiation within 5 years after treatment. Using multivariate Cox proportional hazards modeling, the authors identified thickness of the tumor, location of the tumor's anterior margin relative to the equatorward and the ora serrata, and diameter of the eye plaque used as the best combination of covariables for predicting length of time until development of cataract. Surprisingly, the dose of radiation delivered to the lens, which was strongly correlated to all of these covariables, was not a significant predictive factor in multivariate analysis. The results suggest that success of efforts to decrease the occurrence rate of post-irradiation cataracts by better treatment planning might be limited in patients with posterior uveal melanoma. 21 refs., 2 figs., 5 tabs.

  11. Laser Induced Fluorescence Spectroscopy of Cobalt Monoboride

    NASA Astrophysics Data System (ADS)

    Pang, H. F.; Ng, Y. W.; Cheung, A. S.-C.

    2011-06-01

    Laser induced fluorescence spectrum of cobalt monoboride (CoB) in the visible region between 465 and 560 nm has been observed. CoB molecule was produced by the reaction of laser ablated cobalt atom and diborane (B_2H_6) seeded in argon. Over twenty five vibronic bands have been recorded, and both Co10B and Co11B isotopic species have been observed and analyzed. Preliminary analysis of the rotational lines showed that the observed vibronic bands belong to two categories namely: the Ω' = 2 - Ω'' = 2 and the Ω' = 3 - Ω'' = 3 transitions, which indicated the ground state of CoB is consistent with an assignment of a ^3Δ_i state predicted from ab initio calculations. Unresolved hyperfine structure arising from the Co nucleus (I = 7/2) causes a broadening of spectral lines. This work represents the first experimental investigation of the spectrum of the CoB molecule. Financial support from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. HKU 701008P) is gratefully acknowledged.

  12. Preparation and characterization of electrodeposited cobalt nanowires

    SciTech Connect

    Irshad, M. I. Mohamed, N. M.; Ahmad, F. Abdullah, M. Z.

    2014-10-24

    Electrochemical deposition technique has been used to deposit cobalt nanowires into the nano sized channels of Anodized Aluminium Oxide (AAO) templates. CoCl{sub 2}Ðœ‡6H2O salt solution was used, which was buffered with H{sub 3}BO{sub 3} and acidified by dilute H{sub 2}SO{sub 4} to increase the plating life and control pH of the solution. Thin film of copper around 150 nm thick on one side of AAO template coated by e-beam evaporation system served as cathode to create electrical contact. FESEM analysis shows that the as-deposited nanowires are highly aligned, parallel to one another and have high aspect ratio with a reasonably high pore-filing factor. The TEM results show that electrodeposited cobalt nanowires are crystalline in nature. The Hysteresis loop shows the magnetization properties for in and out of plane configuration. The in plane saturation magnetization (Ms) is lower than out of plane configuration because of the easy axis of magnetization is perpendicular to nanowire axis. These magnetic nanowires could be utilized for applications such as spintronic devices, high density magnetic storage, and magnetic sensor applications.

  13. Nanocomposites of magnetic cobalt nanoparticles and cellulose

    NASA Astrophysics Data System (ADS)

    Pirkkalainen, K.; Leppänen, K.; Vainio, U.; Webb, M. A.; Elbra, T.; Kohout, T.; Nykänen, A.; Ruokolainen, J.; Kotelnikova, N.; Serimaa, R.

    2008-10-01

    Polymeric matrices with stabilized metallic nanoparticles constitute an important class of nanostructured materials, because polymer technology allows fabrication of components with various electronic, magnetic and mechanical properties. The porous cellulose matrix has been shown to be a useful support material for platinum, palladium, silver, copper and nickel nanoparticles. In the present study, nanosized cobalt particles with enhanced magnetic properties were made by chemical reduction within a microcrystalline cellulose (MCC) matrix. Two different chemical reducers, NaBH4 and NaH2PO2, were used, and the so-formed nanoparticles were characterized with X-ray absorption spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. These experimental techniques were used to gain insight into the effect of different synthesis routes on structural properties of the nanoparticles. Magnetic properties of the nanoparticles were studied using a vibrating sample magnetometer. Particles made via the NaBH4 reduction were amorphous Co-B or Co oxide composites with diminished ferromagnetic behaviour and particles made via the NaH2PO2 reduction were well-ordered ferromagnetic hcp cobalt nanocrystals.

  14. Iron- and Cobalt-Catalyzed Alkene Hydrogenation: Catalysis with Both Redox-Active and Strong Field Ligands.

    PubMed

    Chirik, Paul J

    2015-06-16

    hydrogenation of a family of substituted styrene derivatives. Because improved hydrogenation performance was observed with more electron rich supporting ligands, phosphine cobalt(II) dialkyl complexes were synthesized and found to be active for the diastereoselective hydrogenation of various substituted alkenes. Notably, this class of catalysts was activated by hydroxyl functionality, representing a significant advance in the functional group tolerance of base metal hydrogenation catalysts. Through collaboration with Merck, enantioselective variants of these catalysts were discovered by high throughput experimentation. Catalysts for the hydrogenation of functionalized and essentially unfunctionalized alkenes have been discovered using this approach. Development of reliable, readily accessible cobalt precursors facilitated catalyst discovery and may, along with lessons learned from electronic structure studies, provide fundamental design principles for catalysis with earth abundant transition metals beyond alkene hydrogenation.

  15. Model complexes of cobalt-substituted matrix metalloproteinases: tools for inhibitor design.

    PubMed

    Jacobsen, Faith E; Breece, Robert M; Myers, William K; Tierney, David L; Cohen, Seth M

    2006-09-04

    The tetrahedral cobalt(II) complex [(Tp(Ph,Me))CoCl] (Tp(Ph,Me) = hydrotris(3,5-phenylmethylpyrazolyl)borate) was combined with several hydroxypyridinone, hydroxypyridinethione, pyrone, and thiopyrone ligands to form the corresponding [(Tp(Ph,Me))Co(L)] complexes. X-ray crystal structures of these complexes were obtained to determine the mode of binding for each ligand L. The structures show that the [(Tp(Ph,Me))Co(L)] complexes are pentacoordinate complexes, with a general tendency toward square pyramidal geometry. The electronic, EPR, and paramagnetic NMR spectroscopy of the [(Tp(Ph,Me))Co(L)] complexes have been examined. The frozen-solution EPR spectra are indicative of pentacoordination in frozen solution, while the NMR indicates some dynamics in ligand binding. The findings presented here suggest that [(Tp(Ph,Me))Co(L)] complexes can be used as spectroscopic references for investigating the mode of inhibitor binding in metalloproteinases of medicinal interest. Potential limitations when using cobalt(II) model complexes are also discussed.

  16. Separation and Recovery of Cobalt from Copper Leach Solutions

    NASA Astrophysics Data System (ADS)

    Jeffers, T. H.

    1985-01-01

    Significant amounts of cobalt, a strategic and critical metal, are present in readily accessible copper recycling leach solutions. However, cost-effective technology is not available to separate and recover the cobalt from this low-grade domestic source. The Bureau of Mines has developed a procedure using a chelating ion-exchange resin from Dow Chemical Co. to successfully extract cobalt from a pH 3.0 copper recycling solution containing only 30 mg/1 cobalt. Cyclic tests with the commercial resin XFS-4195 in 4-ft-high by 1-in.-diameter columns gave an average cobalt extraction of 95% when 65 bed volumes of solution were processed at a flow rate of 4 gpm/ft.2 Elution of the cobalt using a 50 g/l H2SO4 solution yielded an eluate containing 0.5 gli Co. Selective elution of the loaded resin and solvent extraction procedures using di-2-ethylhexyl phosphoric acid (D2EHPA) and Cyanex 272 removed the impurities and produced a cobalt sulfate solution containing 25 g/l Co.

  17. Cobalt ions induce chemokine secretion in primary human osteoblasts.

    PubMed

    Queally, J M; Devitt, B M; Butler, J S; Malizia, A P; Murray, D; Doran, P P; O'Byrne, J M

    2009-07-01

    Chemokines are major regulators of the inflammatory response and have been shown to play an important role in periprosthetic osteolysis. Titanium particles have previously been shown to induce IL-8 and MCP-1 secretion in osteoblasts. These chemokines result in the chemotaxis and activation of neutrophils and macrophages, respectively. Despite a resurgence in the use of cobalt-chromium-molybdenum alloys in metal-on-metal arthroplasty, cobalt and chromium ion toxicity in the periprosthetic area has been insufficiently studied. In this study we investigate the in vitro effect of cobalt ions on primary human osteoblast activity. We demonstrate that cobalt ions rapidly induce the protein secretion of IL-8 and MCP-1 in primary human osteoblasts. This elevated chemokine secretion is preceded by an increase in the transcription of the corresponding chemokine gene. Using a Transwell migration chemotaxis assay we also demonstrate that the chemokines secreted are capable of inducing neutrophil and macrophage migration. Furthermore, cobalt ions significantly inhibit osteoblast function as demonstrated by reduced alkaline phosphatase activity and calcium deposition. In aggregate these data demonstrate that cobalt ions can activate transcription of the chemokine genes IL-8 and MCP-1 in primary human osteoblasts. Cobalt ions are not benign and may play an important role in the pathogenesis of osteolysis by suppressing osteoblast function and stimulating the production and secretion of chemokines that attract inflammatory and osteoclastic cells to the periprosthetic area.

  18. Production of cobalt and nickel particles by hydrogen reduction

    NASA Astrophysics Data System (ADS)

    Forsman, J.; Tapper, U.; Auvinen, A.; Jokiniemi, J.

    2008-05-01

    Cobalt and nickel nanoparticles were produced by hydrogen reduction reaction from cobalt or nickel chloride precursor vapour in nitrogen carrier gas. This aerosol phase method to produce nanoparticles is a scalable one-step process. Two different setups were introduced in particle production: a batch type reactor and a continuously operated reactor. Common feature in these setups was hydrogen mixing in a vertical flow reactor. The process was monitored on-line for particle mass concentration and for gas phase chemical reactions. Tapered element oscillating microbalance measured the particle mass concentration and Fourier transform infrared spectroscopy was used to monitor relevant gas phase species. The produced cobalt and nickel particles were characterised using transmission electron microscopy and x-ray diffraction. The produced cobalt and nickel particles were crystalline with cubic fcc structure. Twinning was often observed in cobalt particles while nickel particles were mostly single crystals. The cobalt particles formed typically long agglomerates. No significant neck growth between the primary particles was observed. The primary particle size for cobalt and nickel was below 100 nm.

  19. High doses of cobalt induce optic and auditory neuropathy.

    PubMed

    Apostoli, Pietro; Catalani, Simona; Zaghini, Anna; Mariotti, Andrea; Poliani, Pietro Luigi; Vielmi, Valentina; Semeraro, Francesco; Duse, Sarah; Porzionato, Andrea; Macchi, Veronica; Padovani, Alessandro; Rizzetti, Maria Cristina; De Caro, Raffaele

    2013-09-01

    The adverse biological effects of continuous exposure to cobalt and chromium have been well defined. In the past, this toxicity was largely an industrial issue concerning workers exposed in occupational setting. Nevertheless, recent reports have described a specific toxicity mediated by the high levels of cobalt and chromium released by metallic prostheses, particularly in patients who had received hip implants. Clinical symptoms, including blindness, deafness and peripheral neuropathy, suggest a specific neurotropism. However, little is known about the neuropathological basis of this process, and experimental evidence is still lacking. We have investigated this issue in an experimental setting using New Zealand White rabbits treated with repeated intravenous injections of cobalt and chromium, alone or in combination. No evident clinical or pathological alterations were associated after chromium administration alone, despite its high levels in blood and tissue while cobalt-chromium and cobalt-treated rabbits showed clinical signs indicative of auditory and optic system toxicity. On histopathological examination, the animals showed severe retinal and cochlear ganglion cell depletion along with optic nerve damage and loss of sensory cochlear hair cells. Interestingly, the severity of the alterations was related to dosages and time of exposure. These data confirmed our previous observation of severe auditory and optic nerve toxicity in patients exposed to an abnormal release of cobalt and chromium from damaged hip prostheses. Moreover, we have identified the major element mediating neurotoxicity to be cobalt, although the molecular mechanisms mediating this toxicity still have to be defined.

  20. Axial Ligation and Redox Changes at the Cobalt Ion in Cobalamin Bound to Corrinoid Iron-Sulfur Protein (CoFeSP) or in Solution Characterized by XAS and DFT

    PubMed Central

    Schrapers, Peer; Mebs, Stefan; Goetzl, Sebastian; Hennig, Sandra E.; Dau, Holger; Dobbek, Holger; Haumann, Michael

    2016-01-01

    A cobalamin (Cbl) cofactor in corrinoid iron-sulfur protein (CoFeSP) is the primary methyl group donor and acceptor in biological carbon oxide conversion along the reductive acetyl-CoA pathway. Changes of the axial coordination of the cobalt ion within the corrin macrocycle upon redox transitions in aqua-, methyl-, and cyano-Cbl bound to CoFeSP or in solution were studied using X-ray absorption spectroscopy (XAS) at the Co K-edge in combination with density functional theory (DFT) calculations, supported by metal content and cobalt redox level quantification with further spectroscopic methods. Calculation of the highly variable pre-edge X-ray absorption features due to core-to-valence (ctv) electronic transitions, XANES shape analysis, and cobalt-ligand bond lengths determination from EXAFS has yielded models for the molecular and electronic structures of the cobalt sites. This suggested the absence of a ligand at cobalt in CoFeSP in α-position where the dimethylbenzimidazole (dmb) base of the cofactor is bound in Cbl in solution. As main species, (dmb)CoIII(OH2), (dmb)CoII(OH2), and (dmb)CoIII(CH3) sites for solution Cbl and CoIII(OH2), CoII(OH2), and CoIII(CH3) sites in CoFeSP-Cbl were identified. Our data support binding of a serine residue from the reductive-activator protein (RACo) of CoFeSP to the cobalt ion in the CoFeSP-RACo protein complex that stabilizes Co(II). The absence of an α-ligand at cobalt not only tunes the redox potential of the cobalamin cofactor into the physiological range, but is also important for CoFeSP reactivation. PMID:27384529