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Sample records for cobalt ii oxinate

  1. Cobalt(II) Complex of a Diazoalkane Radical Anion.

    PubMed

    Bonyhady, Simon J; Goldberg, Jonathan M; Wedgwood, Nicole; Dugan, Thomas R; Eklund, Andrew G; Brennessel, William W; Holland, Patrick L

    2015-06-01

    β-Diketiminate cobalt(I) precursors react with diphenyldiazomethane to give a compound that is shown by computational studies to be a diazoalkane radical anion antiferromagnetically coupled to a high-spin cobalt(II) ion. Thermolysis of this complex results in formal N-N cleavage to give a cobalt(II) ketimide complex. Experimental evaluation of the potential steps in the mechanism suggests that free azine is a likely intermediate in this reaction. PMID:25986783

  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

    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.

  4. The Nature of the Ground States of Cobalt(II) and Nickel(II) Carboxypeptidase A

    PubMed Central

    Rosenberg, Robert C.; Root, Charles A.; Wang, Run-Han; Cerdonio, Massimo; Gray, Harry B.

    1973-01-01

    The magnetic susceptibilities of cobalt(II) and nickel(II) derivaties of carboxypeptidase A (CPA) follow the Curie law over a wide temperature range. The observed magnetic moments of Co(II)CPA and Ni(II)CPA are 4.77 ± 0.15 and 2.53 ± 0.10 Bohr Magnetons, respectively. The magnetic and spectral properties of Ni(II)CPA are consistent only with an octahedral ground-state geometry, whereas Co(II)CPA has a probable five-coordinate structure. The results establish ordinary metal-ion ground states for two metallocarboxypeptidase A derivatives which exhibit full peptidase activity. PMID:4509646

  5. A novel method for preparation of cobalt(II) and lead(II) carbonates

    NASA Astrophysics Data System (ADS)

    Refat, M. S.; Teleb, S. M.; Sadeek, S. A.

    2004-10-01

    Cobalt(II) carbonate, CoCO 3·4H 2O and lead(II) carbonate, PbCO 3·2H 2O were synthesis by a new simple method during the reaction of aqueous solutions of CoX 2 (X = Cl -, NO 3- and CH 3COO -) and PbX 2 (X = NO 3- or CH 3COO -), respectively, with urea at ˜85 °C for 2 h. The infrared spectra of the reaction products clearly indicates the absence of the bands due to coordinated urea, but show the characteristic bands of ionic carbonate. A general mechanisms describing the formation of cobalt and lead carbonates are suggested.

  6. 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)

  7. 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.

  8. Synthesis and structural characterization of zinc(II) and cobalt(II) complexes based on multidentate hydrazone ligands

    NASA Astrophysics Data System (ADS)

    Li, Li; Zhang, Yuan Zhuo; Liu, E.; Yang, Chengxiong; Golen, James A.; Rheingold, Arnold L.; Zhang, Guoqi

    2016-04-01

    Two multidentate Schiff base ligands containing a hydrazone unit have been synthesized and investigated for zinc(II) and cobalt(II) coordination chemistry. The reactions of the 4-pyridyl derived hydrazone ligand HL1 with zinc(II) or cobalt(II) salts gave three mononuclear complexes that were structurally characterized by X-ray diffraction analysis. The results revealed that the ligand could adopt different coordination modes when various counter anions were employed. While in the case that zinc dichloride was used as a metal salt a neutral mononuclear mono-ligand complex was formed, the deprotonation of hydrazone occurred when zinc(II) or cobalt(II) nitrate were present and two new isostructural mononuclear bis-ligand complexes were isolated. Modification of the hydrazone ligand with oxygen donors was found to have a significant impact on the ligand reactivity, and a similar reaction of H2L2 with cobalt(II) nitrate gave a protonated product of H2L2 without the incorporation of cobalt(II), which features a one-dimensional hydrogen-bonded network in the solid state.

  9. Antifungal cobalt(II), copper(II), nickel(II) and zinc(II) complexes of furanyl-,thiophenyl-, pyrrolyl-, salicylyl- and pyridyl-derived cephalexins.

    PubMed

    Chohan, Zahid H; Pervez, Humayun; Khan, Khalid M; Rauf, A; Maharvi, Ghulam M; Supuran, Claudiu T

    2004-02-01

    Some novel cephalexin-derived furanyl, thiophenyl, pyrrolyl, salicylyl and pyridyl Schiff's bases and their cobalt (II), copper (II), nickel (II) and zinc (II) complexes have been synthesized and studied for their antifungal properties against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The presence of metal ions in the investigated Schiff's base complexes reported here lead to significant antifungal activity, whereas the parent ligands were generally less active. PMID:15202498

  10. Fluorescence characteristic study of the ternary complex of fluoroquinolone antibiotics and cobalt (II) with ATP

    NASA Astrophysics Data System (ADS)

    Wu, Shuqing; Zhang, Wujuan; Chen, Xingguo; Hu, Zhide; Hooper, Martin; Hooper, Beveley; Zhao, Zhengfeng

    2001-05-01

    The results from the measurement of the fluorescence spectra of fluoroquinolone antibiotics including ofloxacin (OF), norfloxacin (NOR) and ciprofloxacin (CIP) complexed with cobalt (II) and ATP give information concerning the antibiotics-nucleotide interactions. From the fluorescence spectral data, it appears that the fluoroquinolone antibiotic cannot directly complex with ATP but indirectly complex with cobalt (II), which is playing an intermediary role. The interaction of fluoroquinolone antibiotic with the nucleotide occurs mainly through the phosphate group. The conclusion offers a more complete mechanism, which is important for understanding the interaction of these drugs with DNA.

  11. Strong Exchange Coupling in a Trimetallic Radical-Bridged Cobalt(II)-Hexaazatrinaphthylene Complex.

    PubMed

    Moilanen, Jani O; Chilton, Nicholas F; Day, Benjamin M; Pugh, Thomas; Layfield, Richard A

    2016-04-25

    Reducing hexaazatrinaphthylene (HAN) with potassium in the presence of 18-c-6 produces [{K(18-c-6)}HAN], which contains the S=1/2 radical [HAN](.-) . The [HAN](.-) radical can be transferred to the cobalt(II) amide [Co{N(SiMe3 )2 }2 ], forming [K(18-c-6)][(HAN){Co(N'')2 }3 ]; magnetic measurements on this compound reveal an S=4 spin system with strong cobalt-ligand antiferromagnetic exchange and J≈-290 cm(-1) (-2 J formalism). In contrast, the Co(II) centres in the unreduced analogue [(HAN){Co(N'')2 }3 ] are weakly coupled (J≈-4.4 cm(-1) ). The finding that [HAN](.-) can be synthesized as a stable salt and transferred to cobalt introduces potential new routes to magnetic materials based on strongly coupled, triangular HAN building blocks. PMID:26997130

  12. Cobalt(II) Oxidation by the Marine Manganese(II)-Oxidizing Bacillus sp. Strain SG-1

    PubMed Central

    Lee, Yoon; Tebo, Bradley M.

    1994-01-01

    The geochemical cycling of cobalt (Co) has often been considered to be controlled by the scavenging and oxidation of Co(II) on the surface of manganese [Mn(III,IV)] oxides or manganates. Because Mn(II) oxidation in the environment is often catalyzed by bacteria, we have investigated the ability of Mn(II)-oxidizing bacteria to bind and oxidize Co(II) in the absence of Mn(II) to determine whether some Mn(II)-oxidizing bacteria also oxidize Co(II) independently of Mn oxidation. We used the marine Bacillus sp. strain SG-1, which produces mature spores that oxidize Mn(II), apparently due to a protein in their spore coats (R.A. Rosson and K. H. Nealson, J. Bacteriol. 151:1027-1034, 1982; J. P. M. de Vrind et al., Appl. Environ. Microbiol. 52:1096-1100, 1986). A method to measure Co(II) oxidation using radioactive 57Co as a tracer and treatments with nonradioactive (cold) Co(II) and ascorbate to discriminate bound Co from oxidized Co was developed. SG-1 spores were found to oxidize Co(II) over a wide range of pH, temperature, and Co(II) concentration. Leucoberbelin blue, a reagent that reacts with Mn(III,IV) oxides forming a blue color, was found to also react with Co(III) oxides and was used to verify the presence of oxidized Co in the absence of added Mn(II). Co(II) oxidation occurred optimally around pH 8 and between 55 and 65°C. SG-1 spores oxidized Co(II) at all Co(II) concentrations tested from the trace levels found in seawater to 100 mM. Co(II) oxidation was found to follow Michaelis-Menten kinetics. An Eadie-Hofstee plot of the data suggests that SG-1 spores have two oxidation systems, a high-affinity-low-rate system (Km, 3.3 × 10-8 M; Vmax, 1.7 × 10-15 M · spore-1 · h-1) and a low-affinity-high-rate system (Km, 5.2 × 10-6 M; Vmax, 8.9 × 10-15 M · spore-1 · h-1). SG-1 spores did not oxidize Co(II) in the absence of oxygen, also indicating that oxidation was not due to abiological Co(II) oxidation on the surface of preformed Mn(III,IV) oxides. These

  13. 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. PMID:12009257

  14. Thermochromism and switchable paramagnetism of cobalt(II) in thiocyanate ionic liquids.

    PubMed

    Osborne, Stephen J; Wellens, Sil; Ward, Chris; Felton, Solveig; Bowman, Robert M; Binnemans, Koen; Swadźba-Kwaśny, Małgorzata; Gunaratne, H Q Nimal; Nockemann, Peter

    2015-07-01

    Temperature-dependent switching of paramagnetism of a cobalt(II) complex is observed in an ionic liquid solution. Paramagnetic and thermochromic switching occur simultaneously due to a reversible change in coordination. This reversible switching is possible in the ionic liquid solution, which enables mobility of thiocyanate anions by remaining mobile at low temperatures and acts as an anion reservoir. PMID:26053484

  15. A Trigonal Prismatic Mononuclear Cobalt(II) Complex Showing Single-Molecule Magnet Behavior.

    PubMed

    Novikov, Valentin V; Pavlov, Alexander A; Nelyubina, Yulia V; Boulon, Marie-Emmanuelle; Varzatskii, Oleg A; Voloshin, Yan Z; Winpenny, Richard E P

    2015-08-12

    Single-molecule magnets (SMMs) with one transition-metal ion often rely on unusual geometry as a source of magnetically anisotropic ground state. Here we report a cobalt(II) cage complex with a trigonal prism geometry showing single ion magnet behavior with very high Orbach relaxation barrier of 152 cm(-1). This, to our knowledge, is the largest reported relaxation barrier for a cobalt-based mononuclear SMM. The trigonal prismatic coordination provided by the macrocyclic ligand gives intrinsically more stable molecular species than previously reported SMMs, thus making this type of cage complexes more amendable to possible functionalization that will boost their magnetic anisotropy even further. PMID:26199996

  16. Complexation in cobalt(II)-sulfide(polysulfide)-ion-organic-base-chloroform systems

    SciTech Connect

    Demutskaya, L.N.; Pilipenko, A.T.; Trachevskii, V.V.; Ryabushko, O.P.

    1986-08-01

    It has been shown by the methods of electronic, IR, and ESR spectroscopy, and magnetometry that the occurrence of a set of acid-base and redox processes in a cobalt(II)-sulfide(polysulfide)-ion-cetyltrimethylammonium extraction system in an alkaline medium results in the formation of the coordination compound /(CTA)/sub 6/(Co/sup II//sub 2/Co/sup III//sub 2/S/sub 7-n/(S/sub x/)/sub n/(OH)/sub 2/)//sub m/ (I), where x = 2 to 5. The combined presence of Ni(II) and Co(II) in the analogous system with sulfide ions at first results in the formation of a compound similar to compound I, which is a product of the replacement of cobalt(II) by nickel(II), whose further reaction with nickel(II) is completed with the formation of a complex with a Co(II):Ni(II) ratio equal to 2:3. The higher complexing ability of the polysulfide ions caused the extraction of Ni(II) in the form of an ionic associate with the formula (CTA)/sub 2/-(Ni(S/sub x/)/sub 2/).

  17. 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.

  18. 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.

  19. Synthesis, crystal structures and spectroscopic properties of cobalt(II) complexes with chelating sulfonylamidophosphate ligands

    NASA Astrophysics Data System (ADS)

    Znovjyak, Kateryna O.; Seredyuk, Maksym; Kusz, Joachim; Nowak, Maria; Moroz, Olesia V.; Sliva, Tetiana Yu; Amirkhanov, Vladimir M.

    2015-11-01

    Two new cobalt(II) complexes with general formula Co(L1)2Phen (1) and Co(L2)2Phen (2), in which HL1 = dimethyl phenylsulfonylphosphoramidate and HL2 = dimethyl tosylphosphoramidate, were prepared in one-step synthesis and characterized by IR, UV-VIS spectroscopy, TGA-DTA and elemental analysis. Moreover, the single crystal structures of 1 and 2 were determined by single crystal X-ray diffractometry. Complexes consist of mononuclear units comprising two L1-(or L2-) and phenanthroline ligands bidentatly linked to metal ion. The UV-VIS spectra of complexes in the solid state show broad asymmetric band at 530 nm attributed to the d-d transition of the metal ion. Comparing of these spectra with the absorption spectra in acetone, octahedral environment of the cobalt(II) ion in solution were considered. The structural similarity of 1 and 2 leads to a similar thermal decomposition profile.

  20. Transition Ion Strikes Back: Large Magnetic Susceptibility Anisotropy in Cobalt(II) Clathrochelates.

    PubMed

    Novikov, Valentin V; Pavlov, Alexander A; Belov, Alexander S; Vologzhanina, Anna V; Savitsky, Anton; Voloshin, Yan Z

    2014-11-01

    Transition-metal complexes are rarely considered as paramagnetic tags for NMR spectroscopy due to them generally having relatively low magnetic anisotropy. Here we report cobalt(II) cage complexes with the largest (among the transition-metal complexes) axial anisotropy of magnetic susceptibility, reaching as high as 12.6 × 10(-32) m(3) at room temperature. This remarkable anisotropy, which results from an unusual trigonal prismatic geometry of the complexes and translates into large negative value of the zero-field splitting energy, is high enough to promote reliable paramagnetic pseudocontact shifts at the distance beyond 2 nm. Our finding paves the way toward the applications of cobalt(II) clathrochelates as future paramagnetic tags. Given the incredible stability and functionalization versatility of clathrochelates, the fine-tuning of the caging ligand may lead to new chemically stable mononuclear single-molecule magnets, for which magnetic anisotropy is of importance. PMID:26278750

  1. Slow magnetic relaxation in mononuclear seven-coordinate cobalt(II) complexes with easy plane anisotropy.

    PubMed

    Chen, Lei; Chen, Shu-Yang; Sun, Yi-Chen; Guo, Yu-Mei; Yu, Lu; Chen, Xue-Tai; Wang, Zhenxing; Ouyang, Z W; Song, You; Xue, Zi-Ling

    2015-07-01

    Two mononuclear seven-coordinate cobalt(II) complexes [Co(L)3(NO3)2] (L = 4-tert-butylpyridine, 1; L = isoquinoline, 2) were prepared and structurally analyzed by single-crystal X-ray crystallography. The coordination spheres of 1 and 2 exhibit distorted pentagonal bipyramid geometry. Analysis of their direct-current magnetic data reveals the existence of easy plane anisotropy (D > 0) with a small transverse anisotropy (E), which was further confirmed by high-field electron paramagnetic resonance (HFEPR) spectroscopy. Field-induced slow magnetic relaxations were observed under the applied dc field in complexes 1 and 2 by alternating-current magnetic susceptibility measurements. Importantly, these complexes are new instances of mononuclear high-coordinate cobalt(II)-based single-molecule magnets. PMID:26027953

  2. A multisyringe flow-based system for kinetic-catalytic determination of cobalt(II).

    PubMed

    Chaparro, Laura; Ferrer, Laura; Leal, Luz; Cerdà, Víctor

    2015-02-01

    A kinetic-catalytic method for cobalt determination based on the catalytic effect of cobalt(II) on the oxidative coupling of 1,2-dihydroxyanthraquinone (alizarin) was automated exploiting multisyringe flow injection analysis (MSFIA). The proposed method was performed at pH 9.2, resulting in a discoloration process in the presence of hydrogen peroxide. The fixed-time approach was employed for analytical signal measurement. The spectrophotometric detection was used exploiting a liquid waveguide capillary cell (LWCC), of 1m optical length at 465 nm. The optimization was carried out by a multivariate approach, reaching critical values of 124 µmol L(-1) and 0.22 mol L(-1) for alizarin and hydrogen peroxide, respectively, and 67°C of reagent temperature. A sample volume of 150 µL was used allowing a sampling rate of 30h(-1). Under optimal conditions, calibration curve was linear in the range of 1-200 µg L(-1) Co, achieving a DL of 0.3 µg L(-1) Co. The repeatability, expressed as relative standard deviation (RSD) was lower than 1%. The proposed analytical procedure was applied to the determination of cobalt in cobalt gluconate and different forms of vitamin B12, cyanocobalamin and hydroxicobalamin with successful results showing recoveries around 95%. PMID:25435233

  3. 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.

  4. 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

  5. Multinuclear cobalt(II)-containing heteropolytungstates: structure, magnetism, and electrochemistry.

    PubMed

    Ibrahim, Masooma; Haider, Ali; Lan, Yanhua; Bassil, Bassem S; Carey, Akina M; Liu, Rongji; Zhang, Guangjin; Keita, Bineta; Li, Wenhui; Kostakis, George E; Powell, Annie K; Kortz, Ulrich

    2014-05-19

    Interaction of the trilacunary Keggin polyanions [A-α-XW9O34](10-) (X = Si(IV), Ge(IV)) with Co(II) and phosphate ions in aqueous, basic media and under mild heating leads to the formation of the tetrameric, Co16-containing heteropolytungstates [{Co4(OH)3PO4}4(A-α-XW9O34)4](32-) (X = Si(IV), Ge(IV)). Both polyanions were characterized in the solid state by single-crystal X-ray diffraction, IR spectroscopy, and thermogravimetric and elemental analyses. Furthermore, the electrochemical and magnetic properties of these isostructural polyanions were investigated. PMID:24784955

  6. Hydrogen Peroxide Coordination to Cobalt(II) Facilitated by Second-Sphere Hydrogen Bonding.

    PubMed

    Wallen, Christian M; Palatinus, Lukáš; Bacsa, John; Scarborough, Christopher C

    2016-09-19

    M(H2 O2 ) adducts have been postulated as intermediates in biological and industrial processes; however, only one observable M(H2 O2 ) adduct has been reported, where M is redox-inactive zinc. Herein, direct solution-phase detection of an M(H2 O2 ) adduct with a redox-active metal, cobalt(II), is described. This Co(II) (H2 O2 ) compound is made observable by incorporating second-sphere hydrogen-bonding interactions between bound H2 O2 and the supporting ligand, a trianionic trisulfonamido ligand. Thermodynamics of H2 O2 binding and decay kinetics of the Co(II) (H2 O2 ) species are described, as well as the reaction of this Co(II) (H2 O2 ) species with Group 2 cations. PMID:27560462

  7. 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.

  8. X-ray structural and spectral study of the cobalt(II) chloride complex with papaverine

    SciTech Connect

    Sabirov, V.Kh.; Struchkov, Yu.T.; Nava, E.U.

    1994-05-01

    A complex of cobalt(II) chloride with papaverine is characterized by x-ray diffraction method (autodiffractometer, 1917 reflections, R = 0.080). Crystals are tetragonal, a = b = 18.393(2) {angstrom}, c = 12.396(4) {angstrom}, Z = 4, space group P{bar 4}/n. The crystal structure is composed of tetrahedral [CoCl{sub 4}]{sup 2-} anions situated in a special position on the {bar 4} axis, cations of the protonated papaverine, and two types of water molecules. The structure exhibits short hydrogen-bond-type contacts C-H...Cl between anions and cations and C-H...O between cations.

  9. Spectral studies of coordination compounds of cobalt(II) with thiosemicarbazone of heterocyclic ketone

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Kumar, Umendra

    2005-12-01

    The paper presents the spectral analysis of cobalt(II) complexes with indoxyl thiosemicarbazone (ITSC) of general composition [CoL 2X 2] (where L = ITSC, X = Cl -, NO 3-, (1/2)SO 42-, NCS -). The geometry of the complexes have been characterized by elemental analysis, molar conductance, magnetic susceptibility measurements and spectral (electronic, IR, EPR, 1H NMR, mass) studies. The various physico-chemical techniques suggested a coordination number of six (octahedral) for chloro, nitrato and thiocyanato complexes. Whereas sulfato complex was found to have five coordinate trigonal-bipyramidal geometry. All the complexes are of high spin type showing magnetic moment corresponding to three unpaired electrons.

  10. 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.

  11. 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.

  12. Dimerization of the octaethylporphyrin {pi} cation radical complex of cobalt(II): Thermodynamic, kinetic, and spectroscopic studies

    SciTech Connect

    Ni, Y.; Lee, S.; Wayland, B.B.

    1999-08-23

    One electron oxidation of cobalt(II) can occur from either the cobalt d or porphyrin {pi} orbitals depending on the choice of porphyrin and reaction media. Oxidation of (octaethylporphyrinato)cobalt(II), (OEP)Co{sup II} (1), in the presence of ligands such as H{sub 2}O and CO produces diamagnetic five and six coordinate complexes of cobalt(III). In the absence of additional ligands to coordinate with Co(III) the first oxidation of [(OEP)Co{sup II}]{sup +} (2). Metalloporphyrin {pi} cation radical complexes and dimers of the OEP derivatives have been extensively investigated. This article reports on the interconversion of the paramagnetic (S = 1) monomer, [(OEP)Co{sup II}]{sup +} (2), with a diamagnetic dimer, [(OEP)-Co{sup II}]{sub 2}{sup 2+} (3), in dichloromethane solvant. {sup 1}H NMR shift and line width studies in CD{sub 2}Cl{sub 2} are applied in evaluating the thermodynamic and activation parameters for homolytic dissociation of the diamagnetic dimer (3).

  13. 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.

  14. Growth and characterization of diaquatetrakis (thiocyanato) cobalt (II) mercury (II) N-methyl-2-pyrolidone (CMTWMP) single crystals

    NASA Astrophysics Data System (ADS)

    Potheher, I. Vetha; Madhavan, J.; Rajarajan, K.; Nagaraja, K. S.; Sagayaraj, P.

    2008-01-01

    Single crystals of diaquatetrakis (thiocyanato) cobalt (II) mercury (II) N-methyl-2-pyrolidone, (CoHg(SCN) 4·(H 2O) 2·2(C 3H 6CONCH 3) (abbreviated as CMTWMP) were grown using slow solvent evaporation technique. The structure of the grown crystals was confirmed by single-crystal X-ray diffraction (XRD) technique. The optical properties of the crystals were investigated by Fourier transform infrared (FTIR) and UV-Vis-NIR transmission spectra. The grown crystals of CMTWMP were also subjected to dielectric, photoconductivity, thermal and microhardness studies. The photoconductivity study of CMTWMP confirms the electrochromism behaviour in the sample. The SHG efficiency of the sample was measured by Kurtz and Perry powder technique and its value is almost comparable with KDP.

  15. 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

  16. 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

    2016-06-01

    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

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

    PubMed Central

    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 × 104 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 × 104 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. PMID:22505925

  18. Synthesis, crystal structure and antifungal activity of a divalent cobalt(II) complex with uniconazole.

    PubMed

    Zhang, Yao; Li, Jie; Ren, Guoyu; Qin, Baofu; Ma, Haixia

    2016-06-01

    Azole compounds have attracted commercial interest due to their high bactericidal and plant-growth-regulating activities. Uniconazole [or 1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pent-1-en-3-ol] is a highly active 1,2,4-triazole fungicide and plant-growth regulator with low toxicity. The pharmacological and toxicological properties of many drugs are modified by the formation of their metal complexes. Therefore, there is much interest in exploiting the coordination chemistry of triazole pesticides and their potential application in agriculture. However, reports of complexes of uniconazole are rare. A new cobalt(II) complex of uniconazole, namely dichloridotetrakis[1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl-κN(4))pent-1-en-3-ol]cobalt(II), [CoCl2(C15H18ClN3O)4], was synthesized and structurally characterized by element analysis, IR spectrometry and X-ray single-crystal diffraction. The crystal structural analysis shows that the Co(II) atom is located on the inversion centre and is coordinated by four uniconazole and two chloride ligands, forming a distorted octahedral geometry. The hydroxy groups of an uniconazole ligands of adjacent molecules form hydrogen bonds with the axial chloride ligands, resulting in one-dimensional chains parallel to the a axis. The complex was analysed for its antifungal activity by the mycelial growth rate method. It was revealed that the antifungal effect of the title complex is more pronounced than the effect of fungicide uniconazole for Botryosphaeria ribis, Wheat gibberellic and Grape anthracnose. PMID:27256696

  19. 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)

  20. A novel cobalt(II)-molybdenum(V) phosphate organic-inorganic hybrid polymer

    SciTech Connect

    Shi, F.-N.; Almeida Paz, Filipe A.; Girginova, Penka I.; Nogueira, Helena I.S.; Rocha, Joao; Amaral, Vitor S.; Klinowski, Jacek; Trindade, Tito . E-mail: ttrindade@dq.ua.pt

    2006-05-15

    A new organic-inorganic hybrid cobalt(II)-molybdenum(V) phosphate polymer incorporating piperazine (pip) (H{sub 2}pip){sub 3}[Co{sub 3}Mo{sub 12}O{sub 24}(OH){sub 6}(PO{sub 4}){sub 8}(H{sub 1.5}pip){sub 4}].5(H{sub 2}O), was prepared under hydrothermal conditions. As revealed by single-crystal X-ray diffraction studies, the material is modular, built from a secondary building block composed of two anionic hexameric polyoxomolybdophosphate [Mo{sub 6}O{sub 12}(OH){sub 3}(PO{sub 4}){sub 4}]{sup 9-} moieties, bridged by a central octahedral Co{sup 2+} centre. The sandwich-type {l_brace}Co[Mo{sub 6}O{sub 12}(OH){sub 3}(PO{sub 4}){sub 4}]{sub 2}{r_brace}{sup 16-} dimers are connected via tetrahedral Co{sup 2+} metal centres, forming an infinite one-dimensional polymer. The compound constitutes the first example of a reduced sandwich-type cobalt-molybdenum phosphate in which the organic moiety (pip) is effectively coordinated to the inorganic backbone of the polymer, in this case via the tetrahedrally coordinated Co{sup 2+} centres. The magnetic behaviour of this material was investigated in the temperature range 4-298 K.

  1. 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.

  2. Ligand contributions to the electronic structures of the oxidized cobalt(II) salen complexes.

    PubMed

    Kochem, Amélie; Kanso, Hussein; Baptiste, Benoit; Arora, Himanshu; Philouze, Christian; Jarjayes, Olivier; Vezin, Hervé; Luneau, Dominique; Orio, Maylis; Thomas, Fabrice

    2012-10-15

    Square planar cobalt(II) complexes of salen ligands N,N'-bis(3-tert-butyl-5R-salicylidene)-1,2-cyclohexanediamine), where R = OMe (1) and tert-butyl (2), were prepared. 1 and 2 were electrochemically reversibly oxidized into cations [1-H(2)O](+) and [2-H(2)O](+) in CH(2)Cl(2). The chemically generated [1-H(2)O](SbF(6))·0.68 H(2)O·0.82CH(2)Cl(2) and [2-H(2)O](SbF(6))·0.3H(2)O·0.85CH(2)Cl(2) were characterized by X-ray diffraction and NIR spectroscopy. Both complexes are paramagnetic species containing a square pyramidal cobalt ion coordinated at the apical position by an exogenous water molecule. They exhibit remarkable NIR bands at 1220 (7370 M(-1) cm(-1)) and 1060 nm (5560 M(-1) cm(-1)), respectively, assigned to a CT transition. DFT calculations and magnetic measurements confirm the paramagnetic (S = 1) ground spin state of the cations. They show that more than 70% of the total spin density in [1-H(2)O](+) and [2-H(2)O](+) is localized on the metal, the remaining spin density being distributed over the aromatic rings (30% phenoxyl character). In the presence of N-methylimidazole 1 and 2 are irreversibly oxidized by air into the genuine octahedral cobalt(III) bis(phenolate) complexes [1-im(2)](+) and [2-im(2)](+), the former being structurally characterized. Neither [1-im(2)](+) nor [2-im(2)](+) exhibits a NIR feature in its electronic spectrum. 1 and 2 were electrochemically two-electron oxidized into [1](2+) and [2](2+). The cations were identified as Co(III)-phenoxyl species by their characteristic absorption band at ca. 400 nm in the UV-vis spectrum. Coordination of the phenoxyl radical to the cobalt(III) metal ion is evidenced by the EPR signal centered at g = 2.00. PMID:23013360

  3. 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. PMID:24564521

  4. 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. PMID:26130568

  5. 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

  6. 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

    2014-11-01

    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. PMID:25192002

  7. 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.

  8. Effect of cobalt(II) chloride hexahydrate on some human cancer cell lines.

    PubMed

    Mahey, Sonia; Kumar, Rakesh; Arora, Rohit; Mahajan, Jyoti; Arora, Saroj; Bhardwaj, Renu; Thukral, Ashwani Kumar

    2016-01-01

    The present study investigates the anti-proliferative and apoptosis inducing mechanism of CoCl2·6H2O in PC-3 cancer cell line. Preliminary, three different forms of cobalt i.e., cobaltous (CoCl2·6H2O), macro-Co(II,III) oxide and nano-Co(II,III) oxide were screened for antiproliferative activity in PC-3 cell line. The CoCl2·6H2O being the most effective antiproliferative agent, hence it was further tested against lung (A549), prostrate (PC-3) and brain (IMR-32) cell lines. Human embryonic kidney cell line (293T) was used as a normal cell line to compare the toxicity of CoCl2·6H2O. The CoCl2·6H2O induced morphological and anatomical changes in PC-3 cancer cell which were studied using light, confocal and scanning electron microscopy. The lactate dehydrogenase was estimated which showed mild necrotic mode of cell death. The Annexin/PI staining confirmed the apoptotic mode of cell death in PC-3 cells. Further, production of reaction of reactive oxygen species and changes in mitochondrial membrane potential was also assessed spectrofluorimetrically. The cell cycle arrest was also investigated using flow cytometery. Finally, the caspase activity was estimated in CoCl2·6H2O treated PC-3 cancer cell line. Interestingly, it was found that CoCl2·6H2O induces more cell death in cancerous cells as compared to normal non-cancerous cells. These findings presented CoCl2·6H2O as potential antiproliferative agent. PMID:27386374

  9. 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

  10. Cobalt(II) "scorpionate" complexes as models for cobalt-substituted zinc enzymes: electronic structure investigation by high-frequency and -field electron paramagnetic resonance spectroscopy.

    PubMed

    Krzystek, J; Swenson, Dale C; Zvyagin, S A; Smirnov, Dmitry; Ozarowski, Andrew; Telser, Joshua

    2010-04-14

    A series of complexes of formula Tp(R,R')CoL, where Tp(R,R'-) = hydrotris(3-R,5-R'-pyrazol-1-yl)borate ("scorpionate") anion (R = tert-butyl, R' = H, Me, 2'-thienyl (Tn), L = Cl(-), NCS(-), NCO(-), N(3)(-)), has been characterized by electronic absorption spectroscopy in the visible and near-infrared (near-IR) region and by high-frequency and -field electron paramagnetic resonance (HFEPR). Reported here are also crystal structures of seven members of the series that have not been reported previously: R' = H, L = NCO(-), N(3)(-); R' = Me, L = Cl(-), NCS(-), NCO(-), N(3)(-); R' = Tn, L = Cl(-), NCS(-). These include a structure for Tp(t-Bu,Me)CoCl different from that previously reported. All of the investigated complexes contain a four-coordinate cobalt(II) ion (3d(7)) with approximate C(3v) point group symmetry about the metal ion and exhibit an S = (3)/(2) high-spin ground state. The use of HFEPR allows extraction of the full set of intrinsic S = (3)/(2) spin Hamiltonian parameters (D, E, and g values). The axial zero-field splitting parameter, D, for all investigated Tp(R,R')CoL complexes is always positive, a fact not easily determined by other methods. However, the magnitude of this parameter varies widely: 2.4 cm(-1) cobalt(II) complexes can enhance the understanding of similar sites in metalloproteins, specifically cobalt-substituted zinc enzymes. PMID:20329727

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

    DOE PAGESBeta

    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.; et al

    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

  12. 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. PMID:26081939

  13. Cobalt(II) complexes with non-steroidal anti-inflammatory drugs and α-diimines.

    PubMed

    Tsiliou, Sofia; Kefala, Lida-Aikaterini; Hatzidimitriou, Antonios G; Kessissoglou, Dimitris P; Perdih, Franc; Papadopoulos, Athanasios N; Turel, Iztok; Psomas, George

    2016-07-01

    Cobalt(II) complexes with a series of non-steroidal anti-inflammatory drugs (diflunisal, flufenamic acid, mefenamic acid and niflumic acid) in the presence of nitrogen-(2,2'-bipyridylamine, 2,2'-bipyridine, 1,10-phenanthroline) and/or oxygen-donor ligands (methanol) have been synthesized and characterized with physicochemical and spectroscopic techniques. The deprotonated NSAID ligands are coordinated to Co(II) ion through their carboxylato groups in diverse binding modes. The crystal structures of complexes [Co(diflunisal-O)2(methanol)4], [Co(niflumato-O)2(methanol)4], [Co(flufenamato-O,O')2(2,2'-bipyridylamine)], [Co(mefenamato-O,O')2(2,2'-bipyridylamine)] and [Co3(flufenamato-O,O')4(flufenamato-O,O,O')2(2,2'-bipyridine)2] have been determined by X-ray crystallography. The interaction of the complexes with serum albumins was studied by fluorescence emission spectroscopy and the albumin-binding constants were determined. The ability of the complexes to scavenge 1,1-diphenyl-picrylhydrazyl, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) and hydroxyl radicals was investigated and the complexes were more active than the corresponding free drugs. Spectroscopic (UV and fluorescence), electrochemical (cyclic voltammetry) and physicochemical (viscosity measurements) techniques were employed in order to study the binding mode of the complexes to calf-thymus (CT) DNA and to calculate the corresponding binding constants; for all complexes, intercalation was suggested as the most possible DNA-binding mode. PMID:26775611

  14. Spectral and magnetic studies on manganese(II), cobalt(II) and nickel(II) complexes with Schiff bases

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Kumar, Umendra

    2005-01-01

    Mn(II), Co(II) and Ni(II) complexes of 2-methylcyclohexanone thiosemicarbazone(MCHTSC L 1) and 2-methylcyclohexanone - 4N-methyl-3-thiosemicarbazone (MCHMTSC L 2), general composition [M(L) 2X 2] (where M = Mn(II), Co(II), Ni(II), L = L 1 or L 2 and X = Cl -, NO 3-, and 1/2SO42-) have been synthesized and characterized by elemental analysis, magnetic susceptibility measurements, UV-vis, IR, EPR, and mass spectral studies. Various physico-chemical techniques suggest an octahedral geometry for all the complexes.

  15. Synthesis of highly luminescent cobalt(ii)-bis(8-hydroxyquinoline) nanosheets as isomeric aromatic amine probes

    NASA Astrophysics Data System (ADS)

    Li, Haibing; Li, Yuling

    2009-09-01

    Highly luminescent and water-soluble cobalt(ii)-bis(8-hydroxyquinoline) (CoQ2) nanosheets have been successfully synthesized via a simple, rapid sonochemical method. The water-soluble CoQ2 nanosheets were characterized by luminescence spectroscopy, UV-vis spectroscopy, FT-IR spectroscopy and transmission electron microscopy (TEM). The CoQ2 nanosheets allow highly sensitive and selective determination of p-nitroaniline via fluorescence quenching. Under optimal conditions, the relative fluorescence intensities of nanosheets decreased linearly with increasing p-nitroaniline. However, the sensitivity of CoQ2 nanosheets toward other aromatic amines including o-diaminobenzene, m-diaminobenzene, p-diaminobenzene, p-toluidine, o-nitroaniline, m-nitroaniline, p-chloroaniline and aniline is negligible. It is found that p-nitroaniline can quench the luminescence of CoQ2 nanosheets in a concentration-dependent manner that is best described by a Stern-Volmer-type equation. The possible underlying mechanism is discussed.Highly luminescent and water-soluble cobalt(ii)-bis(8-hydroxyquinoline) (CoQ2) nanosheets have been successfully synthesized via a simple, rapid sonochemical method. The water-soluble CoQ2 nanosheets were characterized by luminescence spectroscopy, UV-vis spectroscopy, FT-IR spectroscopy and transmission electron microscopy (TEM). The CoQ2 nanosheets allow highly sensitive and selective determination of p-nitroaniline via fluorescence quenching. Under optimal conditions, the relative fluorescence intensities of nanosheets decreased linearly with increasing p-nitroaniline. However, the sensitivity of CoQ2 nanosheets toward other aromatic amines including o-diaminobenzene, m-diaminobenzene, p-diaminobenzene, p-toluidine, o-nitroaniline, m-nitroaniline, p-chloroaniline and aniline is negligible. It is found that p-nitroaniline can quench the luminescence of CoQ2 nanosheets in a concentration-dependent manner that is best described by a Stern-Volmer-type equation

  16. Fluorescence spectrometry for quantitative characterization of cobalt(II) complexation by Leonardite humic acid.

    PubMed

    Monteil-Rivera, Fanny; Dumonceau, Jacques

    2002-11-01

    Quenching of the fluorescence of a Leonardite humic acid by Co(II) has been studied at different pH. The interaction was monitored by emission fluorescence and by synchronous fluorescence with two different offsets (deltalambda=20 and 80 nm). It was found that synchronous fluorescence performed with the smaller offset resolves the individual components of the heterogeneous material better than emission or synchronous fluorescence performed with the larger offset. Enhancement of the signal induced by Cobalt(II) complexation resulted in more complex behavior for measurements performed by synchronous fluorescence with an offset of 20 nm, however. The quenching profiles obtained for pH 5.0, 6.0, and 7.0 ([KNO(3)]=0.1 mol L(-1); [LHA]=3.3 mg(C) L(-1); [Co(II)]=1.0 x 10(-6)-1.6 x 10 (-3) mol L(-1)) by emission and synchronous (deltalambda=80 nm) fluorescence were analyzed by two methods: 1. a non-linear least-squares procedure that leads to conditional constants; and 2. a pH-dependent discrete logK spectrum model that leads to stability constants. The first method resulted in poor fitting and unreasonable values for maximum capacities. The second procedure resulted in smooth fitting that accounted well for the pH changes when results for pH 6.0 and 5.0 were predicted by use of the four values of logK(Co)(i) (4.31, 3.76, 7.32, and 7.67 corresponding to the four sites (i) of the respective pKa(i) values 4, 6, 8, and 10) calculated at pH 7.0 for the equilibrium PMID:12458428

  17. Synthesis, structural, spectroscopic, and magnetic characterization of two-coordinate cobalt(II) aryloxides with bent or linear coordination.

    PubMed

    Bryan, Aimee M; Long, Gary J; Grandjean, Fernande; Power, Philip P

    2014-03-01

    Treatment of the cobalt(II) amide, [Co{N(SiMe3)2}2]2, with four equivalents of the sterically crowded terphenyl phenols, HOAr(Me6) (Ar(Me6) = C6H3-2,6(C6H2-2,4,6-Me3)2) or HOAr(iPr4) (Ar(iPr4) = C6H3-2,6(C6H3-2,6-Pr(i)2)2), produced the first well-characterized, monomeric two-coordinate cobalt(II) bisaryloxides, Co(OAr(Me6))2 (1) and Co(OAr(iPr4))2 (2a and 2b), as red solids in good yields with elimination of HN(SiMe3)2. The compounds were characterized by electronic spectroscopy, X-ray crystallography, and direct current magnetization measurements. The O-Co-O interligand angles in 2a and 2b are 180°, whereas the O-Co-O angle in 1 is bent at 130.12(8)° and its cobalt(II) ion has a highly distorted pseudotetrahedral geometry with close interactions to the ipso-carbons of the two flanking aryl rings. The Co-O distances in 1, 2a, and 2b are 1.858(2), 1.841(1), and 1.836(2) Å respectively. Structural refinement revealed that 1, 2a, and 2b have different fractional occupations of the cobalt site in their crystal structures: 1, 95.0%, 2a, 93.5%, and 2b, 84.6%. Correction of the magnetic data for the different cobalt(II) occupancies showed that the magnetization of 2a and 2b was virtually identical. The effective magnetic moments for 1, 2a, and 2b, 5.646(5), 5.754(5), and 5.636(3) μB respectively, were indicative of significant spin-orbit coupling. The differences in magnetic properties between 1 and 2a/2b are attributed to their different cobalt coordination geometries. PMID:24533728

  18. EPR study of Cu2+ ion doped orotato(nicotinamid)cobalt(II) single crystal

    NASA Astrophysics Data System (ADS)

    Yıldırım, İ.; Karabulut, B.; Büyükgüngör, O.

    2016-01-01

    We have studied the Cu2+ ion doped orotato(nicotinamid)cobalt(II) complex by using EPR spectroscopy and X-ray diffraction. The single crystal is triclinic with the space group P 1 ‾ . 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 Cu2+ 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 = 28 G, Ay = 66 G, Az = 126 G. These data indicate that the symmetry of paramagnetic center is rhombic. We constructed the ground state wave function of the Cu2+ ion.

  19. Spectral studies of cobalt(II) complexes of 12-membered macrocyclic ligands having thiosemicarbazone moieties

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Pundir, Meenakshi

    2007-11-01

    Cobalt(II) complexes of general composition [Co(L)X 2] and [Co(L 1)X 2] where (X = NO 3-, CH 3COO -, Cl -, Br -, NCS -, (1/2)SO 4-2); L = 5,11-diethyl-6,12-dimethyl-3,8-dithione-1,2,4,7,9,10-hexaaza cyclododeca-1,4,6,10-tetraene and L 1 = 5,11-diethyl-6,12-dimethyl-3,8-dione-1,2,4,7,9,10-hexaaza cyclododeca-1,4,6,10-tetraene with tetradentate 12-membered macrocyclic ligands have been synthesized and characterized by elemental analysis, magnetic susceptibility, IR, electronic and electon spin resonance spectral studies. The various physico-chemical techniques suggest a coordination number six (octahedral geometry) for chloro, nitrato, bromo and thiocyanato complexes, and five-coordinated trigonal bipyramidal geometry for sulphato complexes. All the complexes are of high spin type showing magnetic moment corresponding to three unpaired electrons. All the complexes were also screened against bacteria and pathogenic fungi in vitro.

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

    PubMed

    Yıldırım, I; Karabulut, B; Büyükgüngör, O

    2016-01-01

    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. PMID:25704568

  1. Growth of carbon nanofibers using resol-type phenolic resin and cobalt(II) catalyst.

    PubMed

    Kim, Taeyun; Mees, Karina; Park, Ho-Seon; Willert-Porada, Monika; Lee, Chang-Seop

    2013-11-01

    This study investigated carbon nanofibers (CNFs) grown on reticulated vitreous carbon (RVC) foam through catalytic deposition of ethylene. Before growing the CNFs, Co(II) on the RVC foam was expected to act as a catalyst by deposition. The preparation of the CNFs was a two-step process. The first step was preparing the RVC from polyurethane (PU) foam. Changes in weight over time were evaluated using two kinds of resol. The change in the mass and state of the sample with the change in temperature was studied during the carbonization process. The second step was to prepare the CNFs. An OH group was attached by the oxidation of the RVC foam. A change in the shape and mass of the sample was observed due to a change in nitric acid concentration and oxidation time. Then, cobalt was deposited to grow CNFs on the RVC foam. Hydrolysis helped to deposit the Co(ll) on the RVC foam. The appropriate time and temperature were investigated for the reduction process. In the last step, CNFs were prepared by the introducing ethylene gas. The resulting samples were analyzed using scanning electron microscopy, energy dispersive spectroscopy, N2-sorption, and X-ray photoelectron spectroscopy. PMID:24245253

  2. Spectroscopic studies on polymeric cobalt(II) and nickel(II) complexes with bridging succinonitrile and succinonitrile isotopomer ligands

    NASA Astrophysics Data System (ADS)

    Fengler, O. I.; Ruoff, A.

    2002-02-01

    A series of cobalt(II) and nickel(II) complexes were synthesized using succinonitrile and its [1,4- 13C 2]-, [ 15N 2]-, [2,2,3,3- 2H 4]- and [1,4- 13C 2-2,2,3,3- 2H 4]- isotopomers as bridging ligands. Spectroscopic studies, as well as X-ray powder diffraction profiles, were used to identify the nature of the octahedral coordination sphere of the central metal ions and to assign the vibrational spectra in full detail. The succinonitrile ligands were found to be in trans configuration in all the complexes studied and to be coordinated via the lone pairs of their nitrile nitrogens. The rule of mutual exclusion was found to be fulfilled for the succinonitrile ligands under the Ci symmetry of the complexes and the vibrations of the succinonitrile ligands were found to appear in either the infrared or the Raman spectra. All succinonitrile isotopomers exhibited blue-shifts of 43-71 cm -1 upon coordination, while most of the other vibrations remained unchanged or underwent small shifts of only a few wavenumbers. The mass differences of the succinonitrile isotopomers were found to shift mainly the vibrations of the respective affected part of the molecules in comparison with the normal succinonitrile. The exchange of the halides, which are coordinated to the central metal ion, was also found to influence the vibrations of the associated water molecules and we could identify vibrational bands arising due to the H-bond interaction between the halides and the water molecules. Finally, we showed that all complexes under consideration have, spectroscopically, the same symmetry.

  3. Spectroscopic studies on polymeric cobalt(II) and nickel(II) complexes with bridging succinonitrile and succinonitrile isotopomer ligands.

    PubMed

    Fengler, I O; Ruoff, A

    2002-02-01

    A series of cobalt(II) and nickel(II) complexes were synthesized using succinonitrile and its [1,4-13C2], [15N2]-, [2,2,3,3-2H4]- and [1,4-13C,-2,2,3,3-2H4]- isotopomers as bridging ligands. Spectroscopic studies, as well as X-ray powder diffraction profiles, were used to identify the nature of the octahedral coordination sphere of the central metal ions and to assign the vibrational spectra in full detail. The succinonitrile ligands were found to be in trans configuration in all the complexes studied and to be coordinated via the lone pairs of their nitrile nitrogens. The rule of mutual exclusion was found to be fulfilled for the succinonitrile ligands under the Ci symmetry of the complexes and the vibrations of the succinonitrile ligands were found to appear in either the infrared or the Raman spectra. All succinonitrile isotopomers exhibited blue-shifts of 43-71 cm(-1) upon coordination, while most of the other vibrations remained unchanged or underwent small shifts of only a few wavenumbers. The mass differences of the succinonitrile isotopomers were found to shift mainly the vibrations of the respective affected part of the molecules in comparison with the normal succinonitrile. The exchange of the halides, which are coordinated to the central metal ion, was also found to influence the vibrations of the associated water molecules and we could identify vibrational bands arising due to the H-bond interaction between the halides and the water molecules. Finally, we showed that all complexes under consideration have, spectroscopically, the same symmetry. PMID:11905542

  4. Supported cobalt oxide on graphene oxide: highly efficient catalysts for the removal of Orange II from water.

    PubMed

    Shi, Penghui; Su, Ruijing; Zhu, Shaobo; Zhu, Mincong; Li, Dengxin; Xu, Shihong

    2012-08-30

    The current paper investigated the removal of the azo dye Orange II from water using advanced oxidation processes based on sulfate radicals. The cobalt oxide catalyst immobilized on graphene oxide (GO) can activate peroxymonosulfate (PMS) for the degradation of Orange II in water. The Co(3)O(4)/GO catalyst system was characterized via X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and X-ray spectroscopy. Results showed that Co(3)O(4) was distributed on GO. The Co(3)O(4)/GO catalyst system exhibited high activity in Orange II oxidation when the Co(3)O(4)/GO catalyst has an optimum Co(3)O(4) loading. In addition, 100% decomposition could be achieved within 6 min with 0.2mM Orange II, 0.1 g L(-1) catalyst, and 2mM PMS. Meanwhile, inductively coupled plasma analysis revealed that the leach of cobalt ions was low. The catalyst also exhibited stable performance after several rounds of regeneration. Several operational parameters, such as catalyst amount, oxidant amount, pH, temperature, and oxidation rate, affected the degradation of Orange II. PMID:22738772

  5. Molecular design of cage iron(II) and cobalt(II,III) complexes with a second fluorine-enriched superhydrophobic shell.

    PubMed

    Belov, Alexander S; Zelinskii, Genrikh E; Varzatskii, Oleg A; Belaya, Irina G; Vologzhanina, Anna V; Dolganov, Alexander V; Novikov, Valentin V; Voloshin, Yan Z

    2015-02-28

    Pentafluorophenylboron-capped iron and cobalt(II) hexachloroclathrochelate precursors were obtained by the one-pot template condensation of dichloroglyoxime with pentafluorophenylboronic acid on iron and cobalt(II) ions under vigorous reaction conditions in trifluoroacetic acid media. These reactive precursors easily undergo nucleophilic substitution with (per)fluoroarylthiolate anions, giving (per)fluoroarylsulfide macrobicyclic complexes with encapsulated iron and cobalt(II) ions; nucleophilic substitution of the cobalt(II) hexachloroclathrochelate precursor with a pentafluorophenylsulfide anion gave the target hexasulfide monoclathrochelate and the mixed-valence Co(III)Co(II)Co(III) bis-clathrochelate as a side product. The complexes obtained were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV-Vis, (57)Fe Mössbauer (for the X-rayed iron complexes), (1)H, (11)B, (13)C and (19)F NMR spectroscopies and by X-ray diffraction; their redox and electrocatalytic behaviors were studied using cyclic voltammetry and gas chromatography. As can be seen from the single-crystal X-ray diffraction data, the second superhydrophobic shell of such caged metal ions is formed by fluorine atoms of both the apical and ribbed (per)fluoroaryl peripheral groups. The main bond distances and chelate N=C-C=N angles in their molecules are similar, but rotational elongation (contraction) along the molecular C3-pseudoaxes, accompanied by changes in the geometry of the corresponding MN6-coordination polyhedra from a trigonal prism to a trigonal antiprism, allowed encapsulating Fe(2+), Co(2+) and Co(3+) ions. The nature of an encapsulated metal ion and its oxidation state affect the M-N bond lengths, and, for cobalt(ii) clathrochelate with an electronic configuration d(7) the Jahn-Teller structural effect is observed as an alternation of the Co-N distances. Pentafluorophenylboron-capped hexachloroclathrochelate precursors, giving stable catalytically active metal

  6. [Complexes of cobalt (II, III) with derivatives of dithiocarbamic acid--effectors of peptidases of Bacillus thuringiensis and alpha-L-rhamnozidase of Eupenicillium erubescens and Cryptococcus albidus].

    PubMed

    Varbanets, L D; Matseliukh, E V; Seĭfullina, I I; Khitrich, N V; Nidialkova, N A; Hudzenko, E V

    2014-01-01

    The influence of cobalt (II, III) coordinative compounds with derivatives of dithiocarbamic acid on Bacillus thuringiensis IMV B-7324 peptidases with elastase and fibrinolytic activity and Eupenicillium erubescens and Cryptococcus albidus alpha-L-rhamnosidases have been studied. Tested coordinative compounds of cobalt (II, III) on the basis of their composition and structure are presented by 6 groups: 1) tetrachlorocobaltates (II) of 3,6-di(R,R')-iminio-1,2,4,5-tetratiane--(RR')2Ditt[CoCl4]; 2) tetrabromocobaltates (II) of 3,6-di(R,R')-iminio-1,2,4,5-tetratiane--(RR')2Ditt[CoBr4]; 3) isothiocyanates of tetra((R,R')-dithiocarbamatoisothiocyanate)cobalt (II)--[Co(RR'Ditc)4](NCS)2]; 4) dithiocarbamates of cobalt (II)--[Co(S2CNRR')2]; 5) dithiocarbamates of cobalt (III)--[Co(S2CNRR')3]; 6) molecular complexes of dithiocarbamates of cobalt (III) with iodine--[Co(S2CNRR')3] x 2I(2). These groups (1-6) are combined by the presence of the same complexing agent (cobalt) and a fragment S2CNRR' in their molecules. Investigated complexes differ by a charge of intrinsic coordination sphere: anionic (1-2), cationic (3) and neutral (4-6). The nature of substituents at nitrogen atoms varies in each group of complexes. It is stated that the studied coordination compounds render both activating and inhibiting effect on enzyme activity, depending on composition, structure, charge of complex, coordination number of complex former and also on the enzyme and strain producer. Maximum effect is achieved by activating of peptidases B. thuringiensis IMV B-7324 with elastase and fibrinolytic activity. So, in order to improve the catalytic properties of peptidase 1, depending on the type of exhibited activity, it is possible to recommend the following compounds: for elastase--coordinately nonsaturated complexes of cobalt (II) (1-4) containing short aliphatic or alicyclic substituents at atoms of nitrogen and increasing activity by 17-100% at an average; for fibrinolytic

  7. Biological Role of Anions (Sulfate, Nitrate , Oxalate and Acetate) on the Antibacterial Properties of Cobalt (II) and Nickel(II) Complexes With Pyrazinedicarboxaimide Derived, Furanyl and Thienyl Compounds.

    PubMed

    Chohan, Z H; Praveen, M

    1999-01-01

    A number of biologically active complexes of cobalt(II) and nickel(II) with pyrazinedicarboxaimido derived thienyl and furanyl compounds having the same metal ion but different anions such as sulphate, nitrate, oxalate and acetate have been synthesized and characterized on the basis of their physical, spectral and analytical data. In order to evaluate the role of anions on their antibacterial properties, these ligands and their synthesized metal complexes with various anions have been screened against bacterial species Escherichia coil,Pseudomonas aeruginosa and Staphylococcus aureus. The title studies have proved a definitive role of anions in increasing the antibacterial properties. PMID:18475887

  8. Biological Role of Anions (Sulfate, Nitrate , Oxalate and Acetate) on the Antibacterial Properties of Cobalt (II) and Nickel(II) Complexes With Pyrazinedicarboxaimide Derived, Furanyl and Thienyl Compounds

    PubMed Central

    Praveen, M.

    1999-01-01

    A number of biologically active complexes of cobalt(II) and nickel(II) with pyrazinedicarboxaimido derived thienyl and furanyl compounds having the same metal ion but different anions such as sulphate, nitrate, oxalate and acetate have been synthesized and characterized on the basis of their physical, spectral and analytical data. In order to evaluate the role of anions on their antibacterial properties, these ligands and their synthesized metal complexes with various anions have been screened against bacterial species Escherichia coil,Pseudomonas aeruginosa and Staphylococcus aureus. The title studies have proved a definitive role of anions in increasing the antibacterial properties. PMID:18475887

  9. 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.

  10. Substituted oxines inhibit endothelial cell proliferation and angiogenesis†

    PubMed Central

    Bhat, Shridhar; Shim, Joong Sup; Zhang, Feiran; Chong, Curtis Robert; Liu, Jun O.

    2013-01-01

    Two substituted oxines, nitroxoline (5) and 5-chloroquinolin-8-yl phenylcarbamate (22), were identified as hits in a high-throughput screen aimed at finding new anti-angiogenic agents. In a previous study, we have elucidated the molecular mechanism of antiproliferative activity of nitroxoline in endothelial cells, which comprises of a dual inhibition of type 2 human methionine aminopeptidase (MetAP2) and sirtuin 1 (SIRT1). Structure–activity relationship study (SAR) of nitroxoline offered many surprises where minor modifications yielded oxine derivatives with increased potency against human umbilical vein endothelial cells (HUVEC), but with entirely different as yet unknown mechanisms. For example, 5-nitrosoquinolin-8-ol (33) inhibited HUVEC growth with sub-micromolar IC50, but did not affect MetAP2 or MetAP1, and it only showed weak inhibition against SIRT1. Other sub-micromolar inhibitors were derivatives of 5-aminoquinolin-8-ol (34) and 8-sulfonamidoquinoline (32). A sulfamate derivative of nitroxoline (48) was found to be more potent than nitroxoline with the retention of activities against MetAP2 and SIRT1. The bioactivity of the second hit, micromolar HUVEC and MetAP2 inhibitor carbamate 22 was improved further with an SAR study culminating in carbamate 24 which is a nanomolar inhibitor of HUVEC and MetAP2. PMID:22391578

  11. A novel cobalt(II)-selective potentiometric sensor based on p-(4-n-butylphenylazo)calix[4]arene.

    PubMed

    Kumar, Pankaj; Shim, Yoon-Bo

    2009-01-15

    A new poly(vinyl chloride)-based membranes containing p-(4-n-butylphenylazo)calix[4]arene (I) as an electroactive material along with sodiumtetraphenylborate (NaTPB), and dibutyl(butyl)phosphonate in the ratio 10:100:1:200 (I:DBBP:NaTPB:PVC) (w/w) was used to fabricate a new cobalt(II)-selective sensor. It exhibited a working concentration range of 9.2 x 10(-6) to 1.0 x 10(-1)M, with a Nernstian slope of 29.0+/-1.0 mV/decade of activity and the response time of 25s. This sensor shows the detection limit of 4.0 x 10(-6)M. Its potential response remains unaffected of pH in the range, 4.0-7.2, and the cell assembly can be used successfully in partially non-aqueous medium (up to 10%, v/v) without significant change in the slope of working concentration range. The sensor has a lifetime of about 3 months and exhibits excellent selectivity over a number of mono-, bi-, and tri-valent cations including alkali, alkaline earth metal, heavy and transition metal ions. It can be used as an indicator electrode for the end point determination in the potentiometric titration of cobalt ions against ethylenediaminetetraacetic acid (EDTA) as well as for the determination of cobalt ion concentration in real samples. PMID:19064091

  12. 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}.

  13. 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. PMID:21978559

  14. 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.

  15. Synthesis, Biological, Spectral, and Thermal Investigations of Cobalt(II) and Nickel(II) Complexes of N-Isonicotinamido -2′,4′-Dichlorobenzalaldimine

    PubMed Central

    Agarwal, Ram K.; Sharma, Deepak; Singh, Lakshman; Agarwal, Himanshu

    2006-01-01

    A new series of 12 complexes of cobalt(II) and nickel(II) with N-isonicotinamido-2′,4′-dichlorobenzalaldimine (INH-DCB) with the general composition MX2 · n(INH-DCB) [M = Co(II) or Ni(II), X = Cl− ,Br−, NO3−, NCS−, or CH3COO−, n = 2; X = ClO4−, n = 3] have been synthesized. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, infrared, electronic spectra, magnetic susceptibility, and conductivity measurements. An octahedral geometry has been suggested for all the complexes. The metal complexes were screened for their antifungal and antibacterial activities on different species of pathogenic fungi and bacteria and their biopotency has been discussed. PMID:17497006

  16. Clinical imaging with indium 111 oxine-labeled leukocyte scan: review and case report

    SciTech Connect

    Simon, W.H.; Joseph, W.S.

    1988-04-01

    The clinical use and mechanisms of action of technetium 99m pyrophosphate, gallium 67 citrate, and indium 111 oxine have been presented. The diagnosis of osteomyelitis in the lower extremity can often be made on the basis of clinical, laboratory, and conventional radiographic evaluations. In the case report of diabetic osteolysis, initial evaluations revealed osteomyelitis. The use of scanning involving leukocytes labeled with technetium and indium 111 oxine lessened the possibilities of an osseous infection. Studies show the sensitivity, specificity, and accuracy of scans using leukocytes labeled with indium 111 oxine to be superior to those of any other form of nucleotide imaging, but further clinical research is needed.20 references.

  17. Cobalt(II)-Catalyzed Decarboxylative C-H Activation/Annulation Cascades: Regioselective Access to Isoquinolones and Isoindolinones.

    PubMed

    Hao, Xin-Qi; Du, Cong; Zhu, Xinju; Li, Peng-Xiang; Zhang, Jia-Heng; Niu, Jun-Long; Song, Mao-Ping

    2016-08-01

    A new cobalt(II)-catalyzed decarboxylative C-H activation/annulation of benzamides and alkynyl carboxylic acids has been described. Alkynyl carboxylic acids were first employed as the coupling partners using inexpensive Co(OAc)2·4H2O as the catalyst. This method enables a switchable cyclization to isoquinolones and isoindolinones with excellent selectivity. Moreover, a catalytic amount of Ag2O was adopted as co-catalyst and O2 (from air) as a terminal oxidant for the preparation of isoquinolones. PMID:27435354

  18. [Effect of manganese (II), cobalt (II), and nickel (II) ions on the growth and production of coumarins in the suspension culture of Angelica archangelica L].

    PubMed

    Siatka, T; Kasparová, M; Sklenárová, H; Solich, P

    2005-01-01

    The plant cell reacts to an increased concentration of metals in the environment by various mechanisms. They include an increase in the formation of heat-shock proteins, metallothioneins, phytochelatins, amino acids (cysteine, histidine), organic acids (citric, malic), or secondary metabolites. The latter mechanism is being investigated for its possible use in explant cultures for the stimulation of secondary metabolism, which is the source of substances of pharmaceutical importance. The study tested manganese (II) (0, 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, and 50 mM in the medium), cobalt (II), and nickel (II) ions (0, 0.1, 0.5, 1, 5, 10, 50, 100, 200, and 500 microM in the medium) as potential elicitors of coumarin production. At the same time, toxicity of these metals for the culture was examined by evaluating their effect on growth (characterized by fresh and dry weight of biomass at the end of a two-week cultivation). Cultures were cultivated in the dark and in the light. It has been found that the growth of cultures is not influenced by manganese in concentrations ranging from 0 to 2 mM, then it slightly decreases, at a concentration of 50 mM it is lower by 20 % when cultivated in the dark and by 30 % when cultivated in the light in comparison with the control. Cobalt in concentrations of 0 to 50 microM does not significantly influence the growth of the culture, higher concentrations decrease the biomass yields, more markedly when cultivated in the light (at 500 microM Co by 60 %, in the dark only by 30 % in comparison with the controls). Nickel in concentrations of 0.1 to 200 microM does not influence growth, and in a concentration of 500 microM decreases it by approximately 30 % in comparison with the control both in the light and dark. Production of coumarins was not stimulated by any metal in comparison with the control cultures, only the removal of manganese from the medium in the culture cultivated in the dark increased production by about 15 % versus the

  19. 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.

  20. The Interaction of Sheep Genomic DNA with a Cobalt(II) Complex Containing p-Nitrobenzoate and N,N′-Diethylnicotinamide Ligands

    PubMed Central

    Arslantas, Ali; Devrim, A. Kadir; Necefoglu, Hacali

    2007-01-01

    The synthesized cobalt(II) complex, CoPNBDENA and the binding of this complex with sheep genomic DNA were investigated by UV–Visible absorption and viscosity techniques. Also the interaction of sheep genomic DNA with the complex was studied using the agarose gel electrophoresis method. The results indicated that the complex interacted with DNA. The nature of the binding seemed to be mainly an electrostatic interaction between DNA and the cobalt(II) complex. Other binding modes such as hydrogen bonds may also exist in this system. In this study, after the interaction of DNA–CoPNBDENA, it was observed that the migration of the DNA band became slow as the amount of cobalt(II) complex was increased. This clearly demonstrates that the CoPNBDENA complex neutralizes the negative charges of DNA.

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

    NASA Astrophysics Data System (ADS)

    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 N 4O 4 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 [M 2(L)(H 2O) 4] (where M = Co(II) and Ni(II)) and [M 2(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.

  2. Anodic Oxidation and Amperometric Sensing of Hydrazine at a Glassy Carbon Electrode Modified with Cobalt (II) Phthalocyanine–cobalt (II) Tetraphenylporphyrin (CoPc-(CoTPP)4) Supramolecular Complex

    PubMed Central

    Ozoemena, Kenneth I.

    2006-01-01

    This paper describes the electrocatalytic behaviour of a glassy carbon electrode (GCE) modified with cobalt(II)phthalocyanine (CoPc) complex peripherally tetrasubstituted with cobalt(II)tetraphenylporphyrin (CoTPP) complexes via ether linkages (i.e., CoPc-(CoTPP)4). The features of the immobilised pentamer were interrogated with cyclic voltammetry and electrochemical impedance spectroscopy (EIS) using [Fe(CN)6]3-/4- as redox probe revealed enhanced electron transfer properties with kapp ≈ 18 × 10-6 cms-1 compared to that of the bare GCE (4.7 × 10-6 cms-1). The viability of this supramolecular complex as a redox mediator for the anodic oxidation and sensitive amperometric determination of hydrazine in alkaline conditions is described. The electrocatalytic oxidation of hydrazine by GCE-CoPc-(CoTPP)4 was characterised with satisfactory catalytic current response with low non-Faradaic current (ca. 30 times lower than the bare GCE) and at much lower oxidation potential (ca. 300 mV lower than the bare GCE). A mechanism for the studied electrocatalytic reaction was proposed based on the spectrophotometric evidence that revealed the major involvement of the Co(III)/Co(II) redox couple of the central CoPc species rather than the CoTPP component of the pentamer. Rate constant for the anodic oxidation of hydrazine was estimated from chronoamperometry as ∼ 3×103 M-1s-1. The proposed amperometric sensor displayed excellent charateristics towards the determination of hydrazine in 0.2 M NaOH; such as low overpotentials (+100 mV vs Ag|AgCl), very fast amperometric response time (1 s), linear concentration range of up to 230 μM, with micromolar detection limit, high sensitivity and stability.

  3. 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

  4. Oxidation of alkanes by cobalt(II) salts of weakly coordinating anions

    SciTech Connect

    Goldstein, A.S.; Drago, R.S. )

    1991-11-27

    Catalysts which effect the selective oxidation of alkanes under mild reaction conditions are highly desired. Commercial processes exist which involve the oxidation of alkanes by O{sub 2} with cobalt carboxylate catalysts. Elevated temperatures and pressures are required, and the metal ion function is to decompose hydroperoxides formed in a radical-chain process. The authors have demonstrated that a weakly solvated cobalt-acetonitrile complex (Co(NCCH{sub 3}){sub 4})(PF{sub 6}){sub 2}, with a weakly coordinating anion catalyzes the air oxidation of alkanes under mild conditions (75C and 3 atm). Cyclohexane and adamantane are converted to the corresponding alcohol and ketone products. The commercial catalyst for cyclohexane oxidation does not function under these milder conditions. Experiments indicate a mechanism in which the metal ion functions both as an initiator and as a hydroperoxide decomposition catalyst.

  5. 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.

  6. Sequential Binding of Cobalt(II) to Metallo-beta-lactamase CcrA

    SciTech Connect

    Periyannan,G.; Costello, A.; Tierney, D.; Yang, K.; Bennett, b.; Crowder, M.

    2006-01-01

    In an effort to probe Co(II) binding to metallo-{beta}-lactamase CcrA, EPR, EXAFS, and 1H NMR studies were conducted on CcrA containing 1 equiv (1-Co(II)-CcrA) and 2 equiv (Co(II)Co(II)-CcrA) of Co(II). The EPR spectra of 1-Co(II)-CcrA and Co(II)Co(II)-CcrA are distinct and indicate 5/6-coordinate Co(II) ions. The EPR spectra also reveal the absence of significant spin-exchange coupling between the Co(II) ions in Co(II)Co(II)-CcrA. EXAFS spectra of 1-Co(II)-CcrA suggest 5/6-coordinate Co(II) with two or more histidine ligands. EXAFS spectra of Co(II)Co(II)-CcrA also indicate 5/6 ligands at a similar average distance to 1-Co(II)-CcrA, including an average of about two histidines per Co(II). {sup 1}H NMR spectra for 1-Co(II)-CcrA revealed seven paramagnetically shifted resonances, three of which were solvent-exchangeable, while the NMR spectra for Co(II)Co(II)-CcrA showed at least 16 shifted resonances, including an additional solvent-exchangeable resonance and a resonance at 208 ppm. The data indicate sequential binding of Co(II) to CcrA and that the first Co(II) binds to the consensus Zn{sub 1} site in the enzyme.

  7. 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

    Chohan, Z H; Rauf, A

    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

  8. 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

  9. 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. PMID:24259485

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

    SciTech Connect

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

    2013-05-15

    The reaction of 10-(2-benzothiazolylazo)-9-phenanthrol (HL) with cobalt(II) acetate gives the coordination compound [CoL{sub 2}] {center_dot} CHCl{sub 3} (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 HL, L, and CoL{sub 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.

  11. Bovine serum albumin-cobalt(ii) Schiff base complex hybrid: an efficient artificial metalloenzyme for enantioselective sulfoxidation using hydrogen peroxide.

    PubMed

    Tang, Jie; Huang, Fuping; Wei, Yi; Bian, Hedong; Zhang, Wei; Liang, Hong

    2016-05-10

    An artificial metalloenzyme (BSA-CoL) based on the incorporation of a cobalt(ii) Schiff base complex {CoL, H2L = 2,2'-[(1,2-ethanediyl)bis(nitrilopropylidyne)]bisphenol} with bovine serum albumin (BSA) has been synthesized and characterized. Attention is focused on the catalytic activity of this artificial metalloenzyme for enantioselective oxidation of a variety of sulfides with H2O2. The influences of parameters such as pH, temperature, and the concentration of catalyst and oxidant on thioanisole as a model are investigated. Under optimum conditions, BSA-CoL as a hybrid biocatalyst is efficient for the enantioselective oxidation of a series of sulfides, producing the corresponding sulfoxides with excellent conversion (up to 100%), chemoselectivity (up to 100%) and good enantiomeric purity (up to 87% ee) in certain cases. PMID:27075699

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

    PubMed Central

    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

    2015-01-01

    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. PMID:26531811

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  14. 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

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

    PubMed

    Rechkemmer, Yvonne; Breitgoff, Frauke D; van der Meer, Margarethe; Atanasov, Mihail; Hakl, Michael; Orlita, Milan; Neugebauer, Petr; Neese, Frank; 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

  16. Dielectric relaxation spectroscopy of heteronuclear cobalt(II)-copper(II) complex of 1-phenyl-3-methyl-5-pyrazolone

    NASA Astrophysics Data System (ADS)

    Masoud, Mamdouh S.; Ali, Alaa E.; Mohamed, Rabah H.; Mostafa, M. Abd El Zaher

    2005-12-01

    A bright green CoCu(PMP)(OH) 2(H 2O) 2 complex was synthesized. Its structure was elucidated and characterized by different spectroscopic techniques. Both cobalt and copper atoms attain tetrahedral geometry. The complex was investigated by the dielectric relaxation spectroscopy. The dielectric parameters are discussed in terms of temperature and frequency changes. The conductivity of the complex decreased as the temperature increased in the temperature range 30-100 °C, while above this temperature range stepwise increase in the conductivity was observed.

  17. 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)

  18. Cobalt(II)-Based Single-Ion Magnets with Distorted Pseudotetrahedral [N2O2] Coordination: Experimental and Theoretical Investigations.

    PubMed

    Ziegenbalg, Sven; Hornig, David; Görls, Helmar; Plass, Winfried

    2016-04-18

    The synthesis and magnetic properties of cobalt(II) complexes with sterically demanding Schiff-base ligands are reported. The compounds [Co(L(Br))2] (1) and [Co(L(Ph))2]·CH2Cl2 (2·CH2Cl2) are obtained by the reaction of cobalt(II) acetate with the ligands HL(Br) and HL(Ph) in a dichloromethane/methanol mixture. 1 and 2 crystallize in the space groups P21212 and P1̅, respectively. X-ray diffraction studies revealed mononuclear constitution of both complexes. For 1, relatively short intermolecular Co-Co distances of 569 pm are observed. In compound 2, a hydrogen-bonded dichloromethane molecule is present, leading to a solvent aggregate with remarkable thermal stability for which desolvation is taking place between 150 and 210 °C. Magnetic measurements were performed to determine the zero-field-splitting (ZFS) parameter D for both complexes. Frequency-dependent susceptibility measurements revealed slow magnetic relaxation behavior with spin-reversal barriers of 36 cm(-1) for 1 and 43 cm(-1) for 2 at an applied external field of 400 Oe. This observation is related to an increasing distortion of the pseudotetrahedral coordination geometry for complex 2. These distortions can be decomposed in two major contributions. One is the elongation effect described by the parameter ϵT, which is the ratio of the averaged obtuse and acute bond angles. The other effect is related to a twisting distortion of the chelate coordination planes at the cobalt center. A comparison with literature examples reveals that the elongation effect seems to govern the overall magnetic behavior in pseudotetrahedral complexes with two bidentate chelate ligands. Ab initio calculations for complexes 1 and 2 using the CASPT2 method show strong splitting of the excited (4)T2 term, which explains the observed strong ZFS. Spin-orbit calculations with the RASSI-SO method confirm the single-molecule-magnet behavior because only small transversal elements are found for the lowest Kramers doublet for both

  19. 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.

  20. Crystal structure and EPR studies of mixed ligand complex of cobalt(II) with saccharin and ethylisonicotine

    NASA Astrophysics Data System (ADS)

    Uçar, İbrahim; Karabulut, Bünyamin; Bulut, Ahmet; Büyükgüngör, Orhan

    2008-12-01

    The tetraaquabis(ethylisonicotinate)cobalt(II) disaccharinate, [Co(ein) 2(H 2O) 4]·(sac) 2, (CENS), (ein: ethylisonicotinate and sac: saccharinate) complex has been synthesized and its crystal structure has been determined by X-ray diffraction analysis. The title complex crystallizes in monoclinic system with space group P2 1/ c and Z = 2. The Co(II) cations present a slightly distorted CoN 2O 4 octahedral environment, with equatorially coordinated water molecules and axially pyridine N-bound ethylisonicotinate ligands. The magnetic environments of Cu 2+-doped Co(II) complex have been identified by electron paramagnetic resonance (EPR) technique. Cu 2+-doped CENS single crystals have been studied at room temperature in three mutually perpendicular planes. The calculated results of the Cu 2+-doped CENS indicate that Cu 2+ ion substitute with the Co 2+ ion in the host lattice. The angular variations of the EPR spectra have shown that two different Cu 2+ complexes are located in different chemical environments, and each environment contains two magnetically inequvalent Cu 2+sites in distinct orientations occupying substitutional positions in the lattice and show very high angular dependence. The cyclic voltammogram of the title complex investigated in dimethylformamide (DMF) solution exhibits only metal centerd electroactivity in the potential range -1.0-1.25 V versus Ag/AgCl reference electrode.

  1. 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 discussion.…

  2. Structural Variety of Cobalt(II), Nickel(II), Zinc(II), and Cadmium(II) Complexes with 4,4'-Azopyridine: Synthesis, Structure and Luminescence Properties.

    PubMed

    Pladzyk, Agnieszka; Ponikiewski, Łukasz; Dołęga, Anna; Słowy, Klaudia; Sokołowska, Agata; Dziubińska, Katarzyna; Hnatejko, Zbigniew

    2015-11-01

    Self-assembled bi- and polymetallic complexes of Co(II), Ni(II), Zn(II), and Cd(II) were obtained by the reaction of 4,4'-azopyridine (azpy) with metal tri-tert-butoxysilanethiolates (Co, 1; Cd, 2), acetylacetonates (Ni, 3; Zn, 4), and acetates (Cd, 5). All compounds were characterized by single-crystal X-ray structure analysis, elemental analysis, FTIR spectroscopy, and thermogravimetry. Complexes 1, 2 and 4, 5 exhibit diverse structural conformations: 1 is bimetallic, 2 and 4 are 1D coordination polymers, and 5 is a 2D coordination framework formed from bimetallic units. The obtained complexes contain metal atoms bridged by a molecule of azpy. The luminescent properties of 1-5 were investigated in the solid state. PMID:26178314

  3. Four supramolecular isomers of dichloridobis(1,10-phenanthroline)cobalt(II): synthesis, structure characterization and isomerization.

    PubMed

    Chen, Xiaocui; Han, Shumin; Wang, Ruiyao; Li, Yuan

    2016-01-01

    Crystal engineering can be described as the understanding of intermolecular interactions in the context of crystal packing and the utilization of such understanding to design new solids with desired physical and chemical properties. Free-energy differences between supramolecular isomers are generally small and minor changes in the crystallization conditions may result in the occurrence of new isomers. The study of supramolecular isomerism will help us to understand the mechanism of crystallization, a very central concept of crystal engineering. Two supramolecular isomers of dichloridobis(1,10-phenanthroline-κ(2)N,N')cobalt(II), [CoCl2(C12H8N2)2], i.e. (IA) (orthorhombic) and (IB) (monoclinic), and two supramolecular isomers of dichloridobis(1,10-phenanthroline-κ(2)N,N')cobalt(II) N,N-dimethylformamide monosolvate, [CoCl2(C12H8N2)2]·C3H7NO, i.e. (IIA) (orthorhombic) and (IIB) (monoclinic), were synthesized in dimethylformamide (DMF) and structurally characterized. Of these, (IA) and (IIA) have been prepared and structurally characterized previously [Li et al. (2007). Acta Cryst. E63, m1880-m1880; Cai et al. (2008). Acta Cryst. E64, m1328-m1329]. We found that the heating rate is a key factor for the crystallization of (IA) or (IB), while the temperature difference is responsible for the crystallization of (IIA) or (IIB). Based on the crystallization conditions, isomerization behaviour, the KPI (Kitajgorodskij packing index) values and the density data, (IB) and (IIA) are assigned as the thermodynamic and stable kinetic isomers, respectively, while (IA) and (IIB) are assigned as the metastable kinetic products. The 1,10-phenanthroline (phen) ligands interact with each other through offset face-to-face (OFF) π-π stacking in (IB) and (IIB), but by edge-to-face (EF) C-H...π interactions in (IA) and (IIA). Meanwhile, the DMF molecules in (IIB) connect to neighbouring [CoCl2(phen)2] units through two C-H...Cl hydrogen bonds, whereas there are no obvious interactions

  4. Biological role of anions (sulfate, nitrate, oxalate and acetate) on the pharmacological properties of cobalt(II) and nickel(II) chelates with thienoyl- and furenoyl-derived compounds.

    PubMed

    Chohan, Z H; Sherazi, S K; Parveen, M

    1998-01-01

    Biologically active complexes of cobalt (II) and nickel (II) with thienoyl- and furenoyl-derived Schiff-base ligands having the same metal ion but different anions such as sulfate, nitrate, oxalate and acetate have been prepared and characterized. In order to evaluate the role of anions on their pharmacological properties the synthesized complexes have been screened against bacterial species, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and results have been reported. PMID:16414804

  5. A non-aqueous redox flow battery based on tris(1,10-phenanthroline) complexes of iron(II) and cobalt(II)

    NASA Astrophysics Data System (ADS)

    Xing, Xueqi; Zhao, Yicheng; Li, Yongdan

    2015-10-01

    A novel non-aqueous redox flow battery employing tris(1,10-phenanthroline) complexes of iron(II) and cobalt(II) as active species is proposed and investigated for energy storage application. The [Fe(phen)3]2+/3+ and [Co(phen)3]+/2+ (phen = 1,10-phenanthroline) redox couples are used as the positive and negative active materials, respectively, in an electrolyte consisting of TEAPF6 and acetonitrile. Electrochemical measurements display that the two redox couples possess a superior and stable potential difference (E°) with a value of 2.1 V vs. Ag/Ag+. The charge-discharge characteristics of the cell show that the charging and discharging current densities have important influences on the battery performance. Stable cycling performance is obtained with low charge-discharge current densities with an electrolyte flow rate of 25 mL min-1. The coulomb, voltage and energy efficiencies achieve up to 80%, 40% and 39%, respectively.

  6. Vibrational spectra of the Ga(III) complexes with oxine and clioquinol

    NASA Astrophysics Data System (ADS)

    Wagner, Claudia C.; González-Baró, Ana C.; Baran, Enrique J.

    2011-09-01

    The FTIR and FT-Raman spectra of the gallium(III) complexes of 8-hydroxyquinoline (oxine) and 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol), were recorded and briefly discussed by comparison with the spectra of the uncoordinated ligands and with some related species.

  7. 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

  8. Atomic emission line wavelength calculations below 2000 angstroms for Lithium II through Cobalt XXVI

    NASA Technical Reports Server (NTRS)

    Williams, M. D.

    1971-01-01

    Atomic-emission-line wavelengths are presented which were calculated from wavelengths of previously identified transition sequences using second-degree polynomials fitted to known wave numbers by the least squares method. Wavelengths less than 2000 angstroms are included for ions from Li II to Co XXVI. The computer program written in FORTRAN 4 is also included.

  9. Synthesis, antimicrobial, DNA-binding and photonuclease studies of cobalt(III) and nickel(II) Schiff base complexes.

    PubMed

    Sangeetha Gowda, K R; Bhojya Naik, H S; Vinay Kumar, B; Sudhamani, C N; Sudeep, H V; Ravikumar Naik, T R; Krishnamurthy, G

    2013-03-15

    New metal complexes of the type [M(nih)(L)](PF(6))(n)·xH(2)O and [M(nih)(2)](PF(6))·xH(2)O (where M=Co(III) or Ni(II), L=1,10-phenanthroline (phen)/or 2,2' bipyridine (bpy), nih=2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone, n=2 or 1 and x=3 or 2) have been synthesized and characterized by elemental analysis, magnetic, IR and (1)H NMR spectral data. The electronic and magnetic moment 2.97-3.07 B.M. data infers octahedral geometry for all the complexes. The IR data reveals that Schiff base (nih) form coordination bond with the metal ion through azomethine-nitrogen, phenolic-oxygen and carbonyl-oxygen in a tridentate fashion. In addition, DNA-binding properties of these six metal complexes were investigated using absorption spectroscopy, viscosity measurements and thermal denaturation methods. The results indicated that the nickel(II) complex strongly bind with calf-thymus DNA with intrinsic DNA binding constant K(b) value of 4.9×10(4) M(-1) for (3), 4.2×10(4) M(-1) for (4), presumably via an intercalation mechanism compared to cobalt(III) complex with K(b) value of 4.6×10(4) M(-1) (1) and 4.1×10(4) M(-1) (2). The DNA Photoclevage experiment shows that, the complexes act as effective DNA cleavage agent. PMID:23314217

  10. 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. PMID:27098180

  11. 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. PMID:25488702

  12. 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.

  13. Bis(2-amino-3-methyl­pyridine)­dichlorido­cobalt(II)

    PubMed Central

    Tadjarodi, Azadeh; Bijanzad, Keyvan; Notash, Behrouz

    2010-01-01

    In the title compound, [CoCl2(C6H8N2)2], the CoII ion is four-coordinated by two pyridine N atoms from the 2-amino-3-methyl­pyridine ligands and two chloride ions in a distorted tetra­hedral geometry. A weak intra­molecular N—H⋯Cl inter­action occurs. The crystal packing is stabilized by inter­molecular N—H⋯Cl and C—H⋯Cl hydrogen-bond inter­actions. PMID:21587434

  14. Cobalt(II) complex with new terpyridine ligand: An ab initio geometry optimization investigation

    NASA Astrophysics Data System (ADS)

    Ciesielski, Artur; Gorczyński, Adam; Jankowski, Piotr; Kubicki, Maciej; Patroniak, Violetta

    2010-06-01

    Structural parameters of a complex formed between Co(II), and a terpyridine ligand were investigated using the unrestricted Becke three-parameter hybrid exchange functional combined with the Lee-Yang-Parr correlation functional (B3LYP) with the LANL2DZ, 6-31G(d,p), and 6-31G++(d,p) basis sets applied for geometry optimizations. The computations reveal that frequently used methods, which take into consideration primary and secondary interactions, can often be efficient in optimizing structural geometries of systems based on organic molecules and transition-metal ions.

  15. Poly[methylammonium tris(mu(2)-formato-kappa2O:O')cobalt(II)].

    PubMed

    Boca, Miroslav; Svoboda, Ingrid; Renz, Franz; Fuess, Hartmut

    2004-12-01

    The structure of the title compound, {(CH(6)N)[Co(CHO(2))(3)]}(n), consists of a three-dimensional net of central Co(II) ions connected via formate (methanediolate) bridges. The negative charge is compensated by protonated methylamine cations. The CoO(6) chromophores form slightly distorted octahedra, which are bridged by C atoms of formate groups. The central Co atom lies on an inversion center and most of the other atoms lie on an m plane. PMID:15579949

  16. Molecularly Engineered Ru(II) Sensitizers Compatible with Cobalt(II/III) Redox Mediators for Dye-Sensitized Solar Cells.

    PubMed

    Wu, Kuan-Lin; Huckaba, Aron J; Clifford, John N; Yang, Ya-Wen; Yella, Aswani; Palomares, Emilio; Grätzel, Michael; Chi, Yun; Nazeeruddin, Mohammad Khaja

    2016-08-01

    Thiocyanate-free isoquinazolylpyrazolate Ru(II) complexes were synthesized and applied as sensitizers in dye-sensitized solar cells (DSCs). Unlike most other successful Ru sensitizers, Co-based electrolytes were used, and resulting record efficiency of 9.53% was obtained under simulated sunlight with an intensity of 100 mW cm(-2). Specifically, dye 51-57dht.1 and an electrolyte based on Co(phen)3 led to measurement of a JSC of 13.89 mA cm(-2), VOC of 900 mV, and FF of 0.762 to yield 9.53% efficiency. The improved device performances were achieved by the inclusion of 2-hexylthiophene units onto the isoquinoline subunits, in addition to lengthening the perfluoroalkyl chain on the pyrazolate chelating group, which worked to increase light absorption and decrease recombination effects when using the Co-based electrolyte. As this study shows, Ru(II) sensitizers bearing sterically demanding ligands can allow successful utilization of important Co electrolytes and high performance. PMID:27420188

  17. 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.

  18. 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

    2012-05-01

    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

  19. Rates of water exchange for two cobalt(II) heteropolyoxotungstate compounds in aqueous solution.

    PubMed

    Ohlin, C André; 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

    2011-04-11

    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 Co(II) atoms in two polyoxotungstate sandwich molecules using the (17)O-NMR-based Swift-Connick method. The compounds were the [Co(4)(H(2)O)(2)(B-α-PW(9)O(34))(2)](10-) and the larger αββα-[Co(4)(H(2)O)(2)(P(2)W(15)O(56))(2)](16-) ions, each with two water molecules bound trans to one another in a Co(II) 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 [Co(4)(H(2)O)(2)(B-α-PW(9)O(34))(2)](10-) at pH 5.4, we estimate: k(298)=1.5(5)±0.3×10(6) 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 cm(3) mol(-1). For the Wells-Dawson sandwich cluster (αββα-[Co(4)(H(2)O)(2)(P(2)W(15)O(56))(2)](16-)) at pH 5.54, we find: k(298)=1.6(2)±0.3×10(6) 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 cm(3) mol(-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 spectroscopy as S=3/2 Co(II) species (such as the [Co(H(2)O)(6)](2+) monomer ion) and by the significant reduction of the Co-Co vector in the XAS spectra. PMID:21416515

  20. Crystal structure of di-chlorido-bis-(dimethyl N-cyano-dithio-imino-carbonate)cobalt(II).

    PubMed

    Diop, Mouhamadou Birame; Diop, Libasse; Oliver, Allen G

    2016-01-01

    The structure of the mononuclear title complex, [{(H3CS)2C=NC  N}2CoCl2], consists of a Co(II) atom coordinated in a distorted tetra-hedral manner by two Cl(-) ligands and the terminal N atoms of two dimethyl N-cyano-dithio-imino-carbonate ligands. The two organic ligands are almost coplanar, with a dihedral angle of 5.99 (6)° between their least-squares planes. The crystal packing features pairs of inversion-related complexes that are held together through C-H⋯Cl and C-H⋯S inter-actions and π-π stacking [centroid-to-centroid distance = 3.515 (su?) Å]. Additional C-H⋯Cl and C-H⋯S inter-actions, as well as Cl⋯S contacts < 3.6 Å, consolidate the crystal packing. PMID:26870588

  1. Nanoporous cobalt(II) MOF exhibiting four magnetic ground states and changes in gas sorption upon post-synthetic modification.

    PubMed

    Zeng, Ming-Hua; Yin, Zheng; Tan, Yan-Xi; Zhang, Wei-Xiong; He, Yan-Ping; Kurmoo, Mohamedally

    2014-03-26

    We present the syntheses, structural characterization, gas sorption, I2 uptake, and magnetic properties of a double-walled porous metal-organic framework, [Co(II)3(lac)2(pybz)2]·3DMF (1·3DMF, purple, where pybz = 4-pyridyl benzoate, lac = d- and l-lactate) and of its post-synthetic modified (PSM) congeners, [Co(II)3(lac)2(pybz)2]·xGuest (xGuest = 6MeOH, purple; 4.5EtOH, purple; 3PrOH, purple; 2C6H6, purple; 2.7I2, black), [Co(II)3(lac)2(pybz)2] (1, purple), [Co(II)3(pybz)2(lac)2(H2O)2]·7H2O (1a·7H2O, green), and [Co(III)Co(II)2(pybz)2(lac)2(H2O)2]I·2H2O·1.5DMSO (1b·I(-)·2H2O·1.5DMSO, yellow, DMSO = dimethyl sulfoxide). Crystallography shows that the framework is not altered by the replacement of DMF by different solvents or by the removal of the solvent molecules during the single-crystal to single-crystal (SC-SC) transformations, while upon exchange with H2O or partial oxidation by molecular iodine, the crystallinity is affected. 1 absorbs N2, H2, CH4, CH3OH, C2H5OH, PrOH, C6H6, and I2, but once it is in contact with H2O the absorption efficiency is drastically reduced. Upon PSM, the magnetism is transformed from a canted antiferromagnet (1·3DMF and 1·xGuest) to single-chain magnet (1), to a ferrimagnet (1a·7H2O), and to a ferromagnet (1b·I(-)·2H2O·1.5DMSO). Raman spectroscopy suggests the color change (purple to green 1a·7H2O or yellow 1b·I(-)·2H2O·1.5DMSO) is associated with a change of geometry from a strained octahedron due to the very acute chelating angle (∼60°) of the lactate of a cobalt center to a regular octahedron with a monodentate carboxylate and one H2O. The magnetic transformation is explained by the different interchain exchanges (J'), antiferromagnetic for 1·3DMF and 1·xSolvent (J' < 0), SCM for 1 (J' verge to 0), and ferromagnetic for 1a·7H2O (J' > 0), between homometal topological ferrimagnetic chains (two octahedral and one tetrahedral Co(II) ions) connected by the double walls of pybz at 13.3 Å (shortest Co

  2. Solid-state dinuclear-to-trinuclear conversion in an oxalato-bridged chromium(III)-cobalt(II) complex as a new route toward single-molecule magnets.

    PubMed

    Vallejo, Julia; Castro, Isabel; Ferrando-Soria, Jesús; Déniz-Hernández, Maria del Pino; Ruiz-Pérez, Catalina; Lloret, Francesc; Julve, Miguel; Ruiz-García, Rafael; Cano, Joan

    2011-03-21

    A novel bis(oxalato)chromium(III) salt of a ferromagnetically coupled, oxalato-bridged dinuclear chromium(III)-cobalt(II) complex of formula [CrL(ox)(2)CoL'(H(2)O)(2)][CrL(ox)(2)]·4H(2)O (1) has been self-assembled in solution using different aromatic α,α'-diimines as blocking ligands, such as 2,2'-bipyridine (L = bpy) and 2,9-dimethyl-1,10-phenanthroline (L' = Me(2)phen). Thermal dehydration of 1 leads to an intriguing solid-state reaction between the S = 3/2 Cr(III) anions and the S = 3 Cr(III)Co(II) cations to give a ferromagnetically coupled, oxalato-bridged trinuclear chromium(III)-cobalt(II) complex of formula {[CrL(ox)(2)](2)CoL'} (2). Complex 2 possesses a moderately anisotropic S = 9/2 Cr(III)(2)Co(II) ground state, and it exhibits slow magnetic relaxation behavior at very low temperatures (T(B) < 2.0 K). PMID:21401016

  3. 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

  4. Tetra-aqua-bis(nicotinamide-κN)cobalt(II) bis-(2-fluoro-benzoate).

    PubMed

    Ozbek, F Elif; Tercan, Barış; Sahin, Ertan; Necefoğlu, Hacali; Hökelek, Tuncer

    2009-01-01

    The title complex, [Co(C(6)H(6)N(2)O)(2)(H(2)O)(4)](C(7)H(4)FO(2))(2), contains one Co(II) atom (site symmetry ), two monodentate nicotin-amide (NA) ligands, four coordinated water mol-ecules and two 2-fluoro-benzoate (FB) anions. The four O atoms in the equatorial plane around the Co atom form a slightly distorted square-planar arrangement, while the slightly distorted octa-hedral coordination is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxyl group and the adjacent benzene ring is 29.8 (3)°, while the pyridine and benzene rings are oriented at a dihedral angle of 7.97 (12)°. In the crystal structure, mol-ecules are linked by O-H⋯O, N-H⋯O and N-H⋯F hydrogen bonds, forming an infinite three-dimensional network. π-π Contacts between the pyridine and benzene rings [centroid-centroid distance = 3.673 (3) Å] may further stabilize the crystal structure. PMID:21582108

  5. Chemistry of cobalt(II) confined in the pores of ordered silica monoliths: from the formation of the monolith to the CoFe Prussian blue analogue nanocomposite.

    PubMed

    Aouadi, Merwen; Fornasieri, Giulia; Briois, Valérie; Durand, Pierrick; Bleuzen, Anne

    2012-02-27

    Recently we conceived of an original strategy that allows the precipitation of Prussian blue analogues (PBAs) in the ordered pores of silica monoliths to lead to photomagnetic CoFe PBA-silica nanocomposites. To determine the critical parameters and fully control the synthesis of the photoactive CoFe PBA in the pores of the silica matrix, X-ray absorption spectroscopy was performed at the cobalt K-edge. This study showed that cobalt cation chemistry is the keystone of the entire process. The local environment and the electronic structure of the cobalt cation undergo several modifications during the formation process: first the incorporation of the cation as an octahedral complex into the ordered block copolymer phase, then the deprotonation by thermohydrolysis to give a fourfold-coordinated deprotonated lowly condensed species and finally the formation of the 3D coordination network of CoFe PBA in acidic conditions through a rapid reprotonation followed by nucleophilic substitution accompanied by the electronic transfer, thus leading to the photomagnetic Co(III)(LS)-Fe(II)(LS) (LS=low spin) pairs. PMID:22278956

  6. Bis[μ-N-(tert-butyl­dimethyl­silyl)-N-(pyridin-2-ylmeth­yl)amido]­bis­[methyl­cobalt(II)

    PubMed Central

    Malassa, Astrid; Agthe, Christine; Görls, Helmar; Westerhausen, Matthias

    2012-01-01

    The green title complex, [Co2(CH3)2(C12H21N2Si)2], was obtained from bis­{[μ-N-tert-butyl­dimethyl­silyl-N-(pyridin-2-ylmeth­yl)amido]­chloridocobalt(II)} and methyl­lithium in diethyl ether at 195 K via a metathesis reaction. The dimeric cobalt(II) complex exhibits a crystallographic center of inversion in the middle of the Co2N2 ring (average Co—N = 2.050 Å). The CoII atom shows a distorted tetra­hedral coordination sphere. The exocyclic Co—N bond length to the pyridyl group shows a similar value of 2.045 (4) Å. The exocyclic methyl group has a rather long Co—C bond length of 2.019 (5) Å. PMID:22969464

  7. 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

  8. Cobalt(II) phthalocyanine-sensitized hollow Fe3O4@SiO2@TiO2 hierarchical nanostructures: Fabrication and enhanced photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Wu, Song-Hai; Wu, Jing-Long; Jia, Shao-Yi; Chang, Qiao-Wan; Ren, Hai-Tao; Liu, Yong

    2013-12-01

    Cobalt(II) phthalocyanine-sensitized hollow Fe3O4@SiO2@TiO2 hierarchical nanostructures had been successfully obtained by combination of solvothermal processing and dipping processing. The as-obtained products were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), UV-vis diffuse reflectance (DR) and vibrating sample magnetometer (VSM). The results revealed that the cobalt(II) phthalocyanine was successfully grown on the primary Fe3O4@SiO2@TiO2 nanostructures (Fe3O4@SiO2@TiO2@CoPcS). The hollow Fe3O4@SiO2@TiO2@CoPcS hierarchical nanostructure showed excellent photocatalytic efficiency for the degradation of methylene blue (MB) under UV-vis and visible light irradiation. More importantly, the photocatalyst could be effectively separated for reuse by simply applying an external magnetic field. A possible mechanism for the visible photocatalysis with the Fe3O4@SiO2@TiO2@CoPcS heterostructures was suggested.

  9. Cobalt poisoning

    MedlinePlus

    ... and pigments (Cobalt Blue) Magnets Some metal-on-metal hip implants Tires Cobalt was once used as a stabilizer in beer foam. It caused a condition called "beer-drinker's heart," which resulted in heart muscle weakness. This list may not be all-inclusive.

  10. Fine-Tuning of Electronic Structure of Cobalt(II) Ion in Nonplanar Porphyrins and Tracking of a Cross-Hybrid Stage: Implications for the Distortion of Natural Tetrapyrrole Macrocycles.

    PubMed

    Liu, Qiuhua; Zhang, Xi; Zeng, Wennan; Wang, Jianxiu; Zhou, Zaichun

    2015-11-01

    The core size of the porphyrin macrocycles was closely related to their stability of the different electron structure in the central metal ion. Cobalt(II) ions can undergo a conversion in electron configurations upon N4 core contraction of 0.05 Å in nonplanar porphyrins, and these ions still maintain low spin forms after and before conversion. The structural fine-tuning can induce the appearance of a cross-hybrid stage [d(x(2)-y(2))sp(2) ↔ d(z(2))sp(2)] based on quadrilateral coordination of the planar core. The results indicate that the configuration conversion plays a key role in electron transfer in redox catalysis involving cobalt complexes. The electronic properties of six monostrapped cobalt(II) porphyrins were investigated by spectral, paramagnetic, and electrochemical methods. The macrocyclic deformations and size parameters of Co-containing model compounds were directly obtained from their crystal structures. PMID:26461496

  11. Magnetic excitations in an exchange-coupled tetramer cluster of cobalt (II): a study by inelastic neutron scattering

    NASA Astrophysics Data System (ADS)

    Gómez-García, C. J.; Coronado, E.; Borrás-Almenar, J. J.; Aebersold, M.; Güdel, H. U.; Mutka, H.

    1992-06-01

    The polyoxometalate K 10[Co 4(H 2O) 2(PW 9O 34) 2].20H 2O contains a ferromagnetically exchange-coupled tetramer of Co 11 encapsulated in between two diamagnetic molecules (PW 9O 34-9. At 2.5K several inelastic peaks are observed in the energy range 1.5-7 meV, which are assigned to magnetic excitations in the cluster. A tentative interpretation of these data from an anisotropic exchange model yields a cobalt-cobalt interaction of 3meV (24cm -1) and an amount of anisotropy Jxy/ Jz≌0.6. These values are consistent with the magnetic susceptibility measurements.

  12. Mechanism of the Oxo reaction. II. Inhibitory effects of bases and the Broensted acidity of cobalt hydrocarbonyl

    SciTech Connect

    Borovikov, M.S.; Ribakov, V.A.

    1986-09-01

    The relationship between inhibition of the oxo reaction by bases and degree of deprotonation of HCo(CO)/sub 4/ in basic media has been investigated. The inhibitory effect of a Bronsted base (pyridine) on the oxo reaction has been found to correlate quantitatively with the degree of deprotonation of HCo(CO)/sub 4/ at different reaction temperatures and medium polarities. For the reaction of HCo(CO)/sub 4/ with an olefin, the degree of deprotanation of HCo(CO)/sub 4/ correlates quantitatively with the inhibitory effect of a Bronsted base (water). A model involving deprotonation of HCo(CO)/sub 4/ has been proposed for the oxo reaction. Based on this model, the effect of the degree of deprotonation of HCo(CO)/sub 4/ on the distribution of cobalt and rate of the oxo reaction is determined by the presence of a reservoir of cobalt in the form of Co/sub 2/(CO)/sub 8/.

  13. 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. PMID:26844393

  14. 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

  15. 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.

  16. XAFS Studies of Cobalt(II) Binding by Solid Peat and Soil-derived Humic Acids and Plant-derived Humic Acid-like Substances

    SciTech Connect

    Ghabbour,E.; Scheinost, A.; Davies, G.

    2007-01-01

    This work has examined cobalt(II) binding by a variety of solid humic acids (HAs) isolated from peat, plant and soil sources at temperatures down to 60 K. The results confirm that X-ray absorption near-edge spectroscopy (XANES) measurements cannot distinguish between aquo and carboxylato ligands in the inner coordination sphere of Co(II). However, between 1 and 2 inner-sphere carboxylato ligands can be detected in all the peat, plant and soil-derived HA samples by extended X-ray absorption fine structure (EXAFS) measurements, indicating inner-sphere coordination of HA-bound Co(II). The precision of C(carboxylate) detection is limited by the extent and quality of the data and the contribution from inner-sphere O to the Fourier transformed peaks used to detect carbon. Putative chelate ring formation is consistent with a relatively negative entropy change in step A, the stronger Co(II) binding step by HA functional groups, and could relate to 'non-exchangeable' metal binding by HSs.

  17. 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 ( ...

  18. 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.

  19. 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.

  20. 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.

  1. Influence of different physicochemical conditions on the release of indium oxine from nanocapsules.

    PubMed

    Kedzierewicz, F; Thouvenot, P; Monot, I; Hoffman, M; Maincent, P

    1998-03-15

    The main purpose of this study was to determine the influence of factors (pH, enzymes, etc.) chosen partially to mimic in vivo conditions on the release of a model drug, indium oxine, from polyepsiloncaprolactone (PCL) nanocapsules in vitro. A nanocapsule suspension, an emulsion (O/W), and a solution in olive oil were prepared in order to compare the release of a radioactive tracer, indium oxine, as a function of time by an in vitro dialysis method. Nanocapsules were prepared by interfacial deposition of PCL and characterized by particle size distribution (laser light scattering) and determination of the polymer molecular weight by gel permeation chromatography (GPC). The results of this study suggest that the partition coefficient between the acceptor medium and the olive oil is the major parameter governing the release of the isotope, at least in the absence of significant enzyme activity. The PCL wall of nanocapsules is a barrier that does not seem to retard the release of indium. The addition of porcine liver esterases accelerated the degradation of PCL. This study confirms that the release of a drug from nanocapsules may be very different depending on the in vivo location, that is, the administration site. PMID:9492220

  2. Photochemical activation of carbon dioxide by visible light mediated by cobalt(II) and nickel(II) complexes of 1,6-bis(benzimidazol-2-YL)-2, 5-dithiahexane (BBDH)

    SciTech Connect

    Carballo, R.; Castineiras, A.; Hiller, W.; Straehle, J.

    1996-12-01

    Reactions between crystalline Ni(NO{sub 3}){sub 2} or Co(ClO{sub 4}){sub 2} 6H{sub 2}O and 1,6-bis(benzimidazol-2-yl)-2, 5-dithiahexane (BBDH) in ethanol afford the insolubles [Ni(BBDH)(H{sub 2}O){sub 2}](NO{sub 3}){sub 2} or [Co(BBDH)(H{sub 2}O){sub 2}](ClO{sub 4}){sub 2} and coloured solutions. The action of CO{sub 2} and visible light on these suspensions at room temperature yields new nickel(II) or cobalt(II) 2-carboxylato benzimidazolates, [O{sub 2}C-BzIm]{sup 2{minus}}, of formula [Ni{sub 2}(BBDH){sub 2}({mu}{sub 2}-O{sub 2}C-BzIm)](NO{sub 3}){sub 2} (I) and [Co{sub 2}(BBDH){sub 2}({mu}{sub 2}-O{sub 2}-c-BzIm)] (ClO{sub 4}){sub 2} (II), respectively. The crystal and molecular structure of I and II have been elucidated by single crystal X-ray analysis. The complex I crystallizes in the monoclinic space group C2/c, with a = 15.371(3), b = 13.393(3), c = 22.790 (4) {angstrom}, and {beta} = 99.54(4){degrees}. The unit cell comprises four formula units with half the binuclear cation complex in the asymmetric unit. The [O{sub 2}-C-BzIm]{sup 2{minus}} bridges two distorted octahedral nickel(II) ions having a Ni-Ni distance of 5.397(2) {angstrom}. Complex II crystallizes in the triclinic space group P1, with cell data a = 13.351(5), b = 18.960(5), c = 11.379(3) {angstrom},{alpha} = 91.14(2), {beta} = 107.93(3), and {gamma} = 100.88(3){degrees}. The cation complex consists of a dimeric unit with two distorted octahedral cobalt(II) ions being bridged by a 2-carboxylatobenzimidazolato anion, with a Co-Co distance of 5.285(6) {angstrom}. IR spectra are reported. A plausible mechanism by which complexes I and II are formed is also reported. 58 refs.

  3. A non-aqueous all-cobalt redox flow battery using 1,10-phenanthrolinecobalt(II) hexafluorophosphate as active species

    NASA Astrophysics Data System (ADS)

    Xing, Xueqi; Zhang, Dapeng; Li, Yongdan

    2015-04-01

    A non-aqueous all-cobalt redox flow battery, with a cobalt complex 1,10-phenanthrolinecobalt(II) hexafluorophosphate ([Co(phen)3](PF6)2) as the active species, acetonitrile as the solvent and tetraethylammonium hexafluorophosphate (TEAPF6) as the supporting electrolyte, has been investigated. The electrochemical behaviour of oxidation and reduction reactions is measured using cyclic voltammetry (CV). The [Co(phen)3]2+ can be oxidized to [Co(phen)3]3+ and reduced to [Co(phen)3]+. A theoretical cell potential of 1.45 V for one-electron disproportionation reaction is obtained. The electrode reactions show quasi-reversible behaviour and are diffusion controlled. The diffusion coefficients of [Co(phen)3] 2+ for oxidation and reduction reactions are calculated to be 1.35-2.34 × 10-6 cm2 s-1 and 2.50-4.35 × 10-6 cm2 s-1, respectively. The effect of the electrode material is also examined by experiments. The CV curves of [Co(phen)3]2+ on the graphite working electrode show superior peak current and diffusivity to those measured on the glassy-carbon electrode. The charge-discharge performance of the battery is accessed with an H-type glass cell. A coulomb efficiency of about 52% is achieved at 50% state-of-charge for an electrolyte containing of 0.01 M [Co(phen)3]2+ and 0.5 M TEAPF6 in acetonitrile.

  4. Kinetic effect of zinc(II) and cadmium(II) ions on configurational inversion of deltaLLL-fac(S)-tris(L-cysteinato-N,S)cobalt(III) complex.

    PubMed

    Aizawa, S; Ohishi, Y; Yamada, S; Nakamura, M

    2001-02-01

    It has been confirmed from circular dichroism (CD) spectral changes of aqueous solutions of deltaLLL-fac(S)-[Co(L-cys-N,S)3]3- that the absolute configurational inversion to the ALLL isomer is remarkably accelerated by zinc(II), while it is retarded by cadmium(II). In the diluted solutions of these metal ions containing excess deltaLLL-fac(S)-[Co(L-cys-N,S)3]3-, the observed inversion rate constant linearly depends on the zinc(II) concentration with an intercept, while it is not affected by the cadmium(II) concentration. The kinetic behavior has been explained by difference between zinc(II)- and cadmium(II)-interactions with lone pairs on sulfur donor atoms of fac(S)-[Co(L-cys-N,S)3]3-. It has also been proposed that concentrations of zinc(II) and cadmium(II) can be simultaneously determined by the kinetic measurements. PMID:11990552

  5. Tetra­kis(2-amino­pyrazine-κN 4)dichlorido­cobalt(II)

    PubMed Central

    Kang, Wei; Huo, Li-Hua; Gao, Shan; Ng, Seik Weng

    2009-01-01

    The CoII atom in the title complex, [CoCl2(C4H5N3)4], exists in an all-trans Cl2N4Co octa­hedral geometry. The CoII atom lies on a special position of 2 site symmetry. Adjacent mol­ecules are linked by N—H⋯N and N—H⋯Cl hydrogen bonds into a three-dimensional network. PMID:21578553

  6. 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.

  7. 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.

  8. Cobalt(II) amido complexes derived from a monodentate arylamido ligand featuring a highly electron-withdrawing C6F5 substituent.

    PubMed

    Yao, Shuang; Tam, Dennis Yiu Sun; Cheung, Pak Shing; Lam, Chi-Keung; Guo, Pei; Lam, Sik Lok; Lee, Hung Kay

    2015-11-01

    A series of cobalt(ii) complexes of a highly electron-withdrawing amido ligand, [N(C6F5)(C6H3Pr(i)2-2,6)](-) (L), were synthesized and structurally characterized. Mononuclear [CoL(Cl)(TMEDA)] (3) and heterobimetallic [CoL2(μ-Cl)Li(THF)3] (4) were obtained by direct metathetical reactions of anhydrous CoCl2 with one molar equivalent of [LiL(TMEDA)] (1) (TMEDA = Me2NCH2CH2NMe2) and [LiL(THF)3] (2), respectively. Complex 3 underwent facile ligand substitution reactions with LiMe and NaN3, yielding the corresponding mixed-ligand complexes [CoL(X)(TMEDA)] (X = Me 5, N36). Treatment of 3 with NaOMe led to the heterobimetallic complex [CoL2(μ-OMe)Na(TMEDA)] (7). The solid-state structures of complexes 1-7 were established by X-ray diffraction analysis. PMID:26418474

  9. Polymer-inorganic coatings containing nanosized sorbents selective to radionuclides. 1. Latex/cobalt hexacyanoferrate(II) composites for cesium fixation.

    PubMed

    Bratskaya, Svetlana; Musyanovych, Anna; Zheleznov, Veniamin; Synytska, Alla; Marinin, Dmitry; Simon, Frank; Avramenko, Valentin

    2014-10-01

    Here we present a new approach to improve fixation of radionuclides on contaminated surfaces and eliminate their migration after nuclear accidents. The approach consists in fabrication of latex composite coatings, which combine properties of polymeric dust-suppressors preventing radionuclides migration with aerosols and selective inorganic sorbents blocking radionuclides leaching under contact with ground waters and atmospheric precipitates. Latex/cobalt hexacyanoferrate(II) (CoHCF) composites selective to cesium radionuclides were synthesized via "in situ" growth of CoHCF crystal on the surface of carboxylic or amino latexes using surface functional groups as ion-exchange centers for binding precursor ions Co(2+) and [Fe(CN)6](4-). Casting such composite dispersions with variable content of CoHCF on (137)Cs-contaminated sand has yielded protective coatings, which reduced cesium leaching to 0.4% compared to 70% leaching through original latex coatings. (137)Cs migration from the sand surface was efficiently minimized when the volume fraction of CoHCF in the composite film was as low as 0.46-1.7%. PMID:25203389

  10. 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. PMID:25829403

  11. 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.

  12. 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. PMID:17142094

  13. 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.

  14. Decreased sensitivity of early imaging with In-111 oxine-labeled leukocytes in detection of occult infection: concise communication

    SciTech Connect

    Datz, F.L.; Jacobs, J.; Baker, W.; Landrum, W.; Alazraki, N.; Taylor, A. Jr.

    1984-03-01

    Imaging with leukocytes labeled with indium-111 oxine is a sensitive technique for detecting sites of occult infection. Traditionally, imaging is performed 24 hr after injection. The authors undertook a prospective study of 35 patients (40 studies) with possible occult infection to see whether a 24-hr delay in imaging is really necessary. Patients were imaged at 1-4 hr and again at 24 hr after injection. The early images had a sensitivity of only 33%, compared with 95% for the 24-hr images. Of the seven studies that were positive on both early and delayed images, 71% had more intense uptake at 24 hr. There were no false-positive early images. It was concluded that imaging 1-4 hr after injection with In-111 oxine-labeled leukocytes has a low sensitivity for detecting occult infection. However, a positive early image is specific for a site of infection.

  15. Bis(N,N'-dimethyl-ethylenediammonium) tris-(oxalato-κO,O)cobaltate(II) dihydrate: an ion-pair complex.

    PubMed

    Gaye, Papa Aly; Sy, Adama; Thiam, Ibrahima Elhadj; Gaye, Mohamed; Retailleau, Pascal

    2011-09-01

    The Co(II) ion in the title complex, (C(4)H(14)N(2))(2)[Co(C(2)O(4))(3)]·2H(2)O, is coordinated by three oxalate ions, resulting in a distorted octa-hedral geometry. Two uncoordinated water mol-ecules are present in asymmetric unit. Inter-molecular N-H⋯O and O-H⋯O hydrogen bonds between the different entities stabilize the crystal structure. PMID:22058871

  16. Supramolecular control over molecular magnetic materials: γ-cyclodextrin-templated grid of cobalt(II) single-ion magnets.

    PubMed

    Nedelko, Natalia; Kornowicz, Arkadiusz; Justyniak, Iwona; Aleshkevych, Pavlo; Prochowicz, Daniel; Krupiński, Piotr; Dorosh, Orest; Ślawska-Waniewska, Anna; Lewiński, Janusz

    2014-12-15

    Single-ion magnets (SIMs) are potential building blocks of novel quantum computing devices. Unique magnetic properties of SIMs require effective separation of magnetic ions and can be tuned by even slight changes in their coordination sphere geometry. We show that an additional level of tailorability in the design of SIMs can be achieved by organizing magnetic ions into supramolecular architectures, resulting in gaining control over magnetic ion packing. Here, γ-cyclodextrin was used to template magnetic Co(II) and nonmagnetic auxiliary Li(+) ions to form a heterometallic {Co, Li, Li}4 ring. In the sandwich-type complex [(γ-CD)2Co4Li8(H2O)12] spatially separated Co(II) ions are prevented from superexchange magnetic coupling. Ac/dc magnetic and EPR studies demonstrated that individual Co(II) ions with positive zero-field splitting exhibit field-induced slow magnetic relaxation consistent with the SIMs' behavior, which is exceptional in complexes with easy-plane magnetic anisotropy. PMID:25494948

  17. Relative transition probabilities of cobalt

    NASA Technical Reports Server (NTRS)

    Roig, R. A.; Miller, M. H.

    1974-01-01

    Results of determinations of neutral-cobalt transition probabilities measured relative to Co I 4150.43 A and Co II 4145.15 A, using a gas-driven shock tube as the spectroscopic light source. Results are presented for 139 Co I lines in the range from 3940 to 6640 A and 11 Co II lines in the range from 3840 to 4730 A, which are estimated to have reliabilities ranging from 8 to 50%.

  18. Cobalt Alums. A Demonstration Experiment

    NASA Astrophysics Data System (ADS)

    Schäffer, Claus E.; Steenberg, Paul

    2002-08-01

    The demonstration experiment describes the isolation of [Co(H2O)6]3+ both as the pure blue crystalline cesium cobalt alum, CsCo(SO4)2·12H2O, and as a light greenish-blue solid solution of ammonium cobalt alum in (NH4)Al(SO4)2·12H2O. The hexaaquacobalt(III) ion is prepared chemically by oxidation with hydrogen peroxide, taking advantage of the stabilization of CoIII relative to CoII by complexation with the carbonate ligand. A brief description of alum structure and a characterization of alum subclasses are included.

  19. Diaqua­bis(pyridine-2-carboxyl­ato-κ2 N,O)cobalt(II)

    PubMed Central

    Huang, G. S.

    2008-01-01

    In the mol­ecule of the title compound, [Co(C6H4NO2)2(H2O)2], the coordination environment around the CoII atom is distorted octahedral; two N and two O atoms of the pyridine-2-carboxylate ligands lie in the equatorial plane and the two water O atoms in the axial positions. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds link the mol­ecules, forming a supra­moleular network structure. PMID:21202222

  20. Hexaaqua­cobalt(II) 2,2′-[naphthalene-1,8-diylbis(­oxy)]diacetate dihydrate

    PubMed Central

    Shi, Hui Fang; Wu, Tao; Jiang, Peng Gang; Hao, Zhi; Zhang, Miao Miao

    2013-01-01

    In the title compound, [Co(H2O)6](C14H10O6)·2H2O, the 2,2′-[naphthalene-1,8-diylbis(­oxy)]diacetate dianion L is not coordinated to the CoII ion. The asymmetric unit contains half of the L dianion, half of a [Co(H2O)6]2+ cation (both molecules being completed by inversion symmetry), and one water mol­ecule. The crystal packing features O—H⋯O hydrogen bonding between the carboxyl­ate groups, the aqua ligands and the hydrate water mol­ecules. PMID:23424401

  1. Synthesis, characterization and biological activity of complexes of 2-hydroxy-3,5-dimethylacetophenoneoxime (HDMAOX) with copper(II), cobalt(II), nickel(II) and palladium(II)

    NASA Astrophysics Data System (ADS)

    Singh, Bibhesh K.; Jetley, Umesh K.; Sharma, Rakesh K.; Garg, Bhagwan S.

    2007-09-01

    A new series of complexes of 2-hydroxy-3,5-dimethyl acetophenone oxime (HDMAOX) with Cu(II), Co(II), Ni(II) and Pd(II) have been prepared and characterized by different physical techniques. Infrared spectra of the complexes indicate deprotonation and coordination of the phenolic OH. It also confirms that nitrogen atom of the oximino group contributes to the complexation. Electronic spectra and magnetic susceptibility measurements reveal square planar geometry for Cu(II), Ni(II) and Pd(II) complexes and tetrahedral geometry for Co(II) complex. The elemental analyses and mass spectral data have justified the ML 2 composition of complexes. Kinetic and thermodynamic parameters were computed from the thermal decomposition data using Coats and Redfern method. The geometry of the metal complexes has been optimized with the help of molecular modeling. The free ligand (HDMAOX) and its metal complexes have been tested in vitro against Alternarie alternate, Aspergillus flavus, Aspergillus nidulans and Aspergillus niger fungi and Streptococcus, Staph, Staphylococcus and Escherchia coli bacteria in order to assess their antimicrobial potential. The results indicate that the ligand and its metal complexes possess antimicrobial properties.

  2. Diaqua-bis-(2-chloro-benzoato-κO)bis-(nicotinamide-κN (1))cobalt(II).

    PubMed

    Dincel, Oznur; Tercan, Barış; Oztürkkan, Füreya Elif; Necefoğlu, Hacali; Hökelek, Tuncer

    2013-03-01

    In the title complex, [Co(C7H4ClO2)2(C6H6N2O)2(H2O)2], the Co(II) cation is located on an inversion center and is coord-inated by two 2-chloro-benzoate anions, two nicotin-amide (NA) ligands and two water mol-ecules. The four O atoms in the equatorial plane around the Co(II) cation form a slightly distorted square-planar arrangement, while the slightly distorted octa-hedral coordination is completed by the two pyridine N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 29.7 (4)°, while the pyridine and benzene rings are oriented at a dihedral angle of 83.17 (15)°. Intra-molecular O-H⋯O hydrogen bonding occurs between the carboxyl-ate group and coordinating water mol-ecule. In the crystal, inter-molecular N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network. PMID:23476513

  3. Diaqua-bis-(2-iodo-benzoato-κO)bis-(nicotinamide-κN(1))cobalt(II).

    PubMed

    Aydın, Omür; Caylak Delibaş, Nagihan; Necefoğlu, Hacali; Hökelek, Tuncer

    2012-04-01

    In the title complex, [Co(C(7)H(4)IO(2))(2)(C(6)H(6)N(2)O)(2)(H(2)O)(2)], the Co(II) cation is located on an inversion center and is coordinated by two monodentate 2-iodo-benzoate (IB) anions, two nicotin-amide (NA) ligands and two water mol-ecules. The four O atoms in the equatorial plane around the Co(II) cation form a slightly distorted square-planar arrangement, while the slightly distorted octa-hedral coordination is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 22.3 (3)°, while the pyridine ring and the benzene ring are oriented at a dihedral angle of 84.59 (13)°. Intra-molecular O-H⋯O hydrogen bonding occurs between the carboxyl-ate group and coordinated water mol-ecule. In the crystal, N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional supra-molecular network. PMID:22589871

  4. 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…

  5. A new cube-based dodecanuclear cobalt(ii) cluster with azide and tetrazolate ligands exhibiting ferromagnetic ordering.

    PubMed

    Zhang, Xiu-Mei; Li, Peng; Gao, Wei; Liu, Jie-Ping; Gao, En-Qing

    2015-08-14

    A new cubane-based Co(ii) compound, [Co(12)(5-PT)(6)(CO(3))(N(3))2(O)(4)(CH(3)O)(6)(H(2)O)(18)] (1) (5-HPT = 5-phenyl-1H-tetrazole), was synthesized by reaction of 5-HPT, CoCl(2)·6H(2)O and NaN(3) in a methanol solution. In 1, a Co(12) cluster based on three identical Co(4)O(2)(ON)(2) cubane units bridged by a μ(6)-carbonate ligand is linked by π-π stacking interactions between phenylene groups, forming a 3D supramolecular structure. Magnetic investigations indicate that compound 1 exhibits long-range ferromagnetic ordering at about 9 K. The cube-based Co(12) clusters with μ(6)-CO(3)(2-) bridges are unprecedented. PMID:26136165

  6. 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

  7. 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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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 Fe2+ ion in ionic liquid (1-butyl-3-methylimidazoliumbromide) medium at different temperatures (298, 303, 308, 313, 318 and 323 K) 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.

  8. Crystal structure of bis­(di­methyl­ammonium) hexa­aqua­cobalt(II) bis­(sulfate) dihydrate

    PubMed Central

    Held, Peter

    2015-01-01

    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 NiII 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 mol­ecules and di­methyl­ammonium cations connect the sulfate tetrahedra and the [Co(H2O)6]2+ octa­hedron 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). PMID:26029410

  9. 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). PMID:27221950

  10. Effect of Dispersion on Surface Interactions of Cobalt(II) Octaethylporphyrin Monolayer on Au(111) and HOPG(0001) Substrates: a Comparative First Principles Study

    SciTech Connect

    Chilukuri, Bhaskar; Mazur, Ursula; Hipps, Kerry 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.

  11. Saddle-shaped macrocycle distortion and symmetry decrease in cobalt (II) meso-tetraphenylporphyrin: Structure of a dichloromethane solvate and DFT calculations

    NASA Astrophysics Data System (ADS)

    de Melo, Cristiane Cabral; Moreira, Wania da Conceição; Martins, Tássia Joi; Cordeiro, Márcia Regina; Ellena, Javier; Guimarães, Freddy Fernandes; Martins, Felipe Terra

    2014-11-01

    Many studies about porphyrins have emerged in recent years, including studies using porphyrins as building blocks for supramolecular assemblies. Understanding new solid state forms of porphyrins and the elucidation of their structures can have remarkable benefits for nanoscience and synthetic biology. In this study, a new pseudopolymorph of cobalt (II) meso-tetraphenylporphyrin, (CoTPP), was synthesized in a known one-pot reaction, rather than using many-step conventional methods, was isolated and was characterized for the first time by low-temperature single crystal X-ray diffraction. It is a nonstoichiometric solvate assembled into dichloromethane channels. The most striking feature of this structure is the conformation adopted by the porphyrin macrocycle. In contrast to the non-solvated form of CoTPP that exhibits a ruffled core distortion and crystallizes in the tetragonal space group I-42d, this solvated form has been crystallized in the triclinic space group Pī and shows a distinct saddle-shaped macrocycle distortion. In the triclinic form, the conformation of one of the four phenyl rings is remarkably different from the others. A potential energy surface scan of the torsional angles around the bonds between this phenyl moiety and the macrocycle of CoTPP in both the non-solvated and the solvate forms demonstrates that the saddle-shaped macrocycle distortion depends on the unusual phenyl conformation. The distortion is responsible for the symmetry decrease in the channel solvate form, causing a loss of the 4-fold rotoinversion axis observed in the non-solvated tetragonal phase, which has identical phenyl conformations.

  12. 3D chiral and 2D achiral cobalt(ii) compounds constructed from a 4-(benzimidazole-1-yl)benzoic ligand exhibiting field-induced single-ion-magnet-type slow magnetic relaxation.

    PubMed

    Wang, Yu-Ling; Chen, Lin; Liu, Cai-Ming; Du, Zi-Yi; Chen, Li-Li; Liu, Qing-Yan

    2016-05-01

    Organizing magnetically isolated 3d transition metal ions, which behave as single-ion magnet (SIM) units, in a coordination network is a promising approach to design novel single-molecule magnets (SMMs). Herein 3D chiral and 2D achiral cobalt(ii) coordination compounds based on single metal nodes with a 4-(benzimidazole-1-yl)benzoic acid (Hbmzbc) ligand, namely, [Co(bmzbc)2(1,2-etdio)]n () (1,2-etdio = 1,2-ethanediol) and [Co(bmzbc)2(Hbmzbc)]n (), have been synthesized and structurally characterized. The 3D chiral structure with 2-fold interpenetrating qtz topological nets consisting of totally achiral components was obtained via spontaneous resolution, while the achiral structure is a 2D (4,4) net. In both structures, individual cobalt(ii) ions are spatially well separated by the long organic ligands in the well-defined networks. Magnetic measurements on and showed field-induced slow magnetic relaxation resulting from single-ion anisotropy of the individual Co(ii) ions. Analysis of the dynamic ac susceptibilities with the Arrhenius law afforded an anisotropy energy barrier of 16.8(3) and 31.3(2) K under a 2 kOe static magnetic field for and , respectively. The distinct coordination environments of the Co(ii) ions in and lead to the different anisotropic energy barriers. PMID:27054774

  13. 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. PMID:17252947

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

    PubMed Central

    2014-01-01

    Anhydrous CoCl2 or [NiCl2(DME)] reacts with the ligand PCPMe-iPr (1) in the presence of nBuLi to afford the 15e and 16e square planar complexes [Co(PCPMe-iPr)Cl] (2) and [Ni(PCPMe-iPr)Cl] (3), respectively. Complex 2 is a paramagnetic d7 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(PCPMe-iPr)(CO)Cl] (4) and [Co(PCPMe-iPr)(py)Cl] (5), respectively, while in the presence of Ag+ and CO the cationic complex [Co(PCPMe-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 d7 low-spin configuration with some degree of spin–orbit coupling. Oxidation of 2 with CuCl2 affords the paramagnetic Co(III) PCP complex [Co(PCPMe-iPr)Cl2] (7), while the synthesis of the diamagnetic Co(I) complex [Co(PCPMe-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(PCPMe-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(PCPMe-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.

  15. Preparation and Anti-Tumour Activity of Some Arylbismuth(III) Oxine Complexes.

    PubMed

    Smith, K A; Deacon, G B; Jackson, W R; Tiekink, E R; Rainone, S; Webster, L K

    1998-01-01

    New arylbismuth(lll) oxinates, PhBi(MeOx)(2), (p-MeC(6)H(4))Bi(Ox)(2), (p-MeC(6)H(4))Bi(MeOx)(2), (p-ClC(6)H(4))Bi(Ox)(2), and (p-ClC(6)H(4))Bi(MeOx)(2) (Ox(-) = quinolin-8-olate and MeOx(-)=2-methylquinolin-8-olate) have been prepared by reaction of the appropriate diarylbismuth chlorides with Na(Ox) or Na(MeOx) in the presence of 15-crown-5. An X-ray crystallographic study has shown PhBi(MeOx)(2) to be a five coordinate monomer with distorted square pyramidal stereochemistry. Chelating MeOx ligands have a cisoid arrangement in the square plane and the phenyl group is apical. The lattice is stabilised by significant pi-pi interactions between centrosymmetric molecules. A range of these complexes has been shown to have high in vitro biological activity (comparable with or better than cisplatin) against L1210 leukaemia, the corresponding cisplatin resistant line, and a human ovarian cell line, SKOV-3. However, initial in vivo testing against a solid mouse plasmacytoma (PC6) and P388 leukaemia has not revealed significant activity. PMID:18475861

  16. 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.

  17. Role of Spin States in Nitric Oxide Binding to Cobalt(II) and Manganese(II) Porphyrins. Is Tighter Binding Always Stronger?

    PubMed

    Radoń, Mariusz

    2015-06-15

    Binding of nitric oxide (NO) to metalloporphyrins and heme groups is important in biochemistry while challenging to describe accurately by density functional theory (DFT) calculations. Here, the structural and thermochemical aspect of NO binding to Co(II) and Mn(II) porphyrins is investigated by DFT and DFT-D (dispersion-corrected) calculations, supported by reliable coupled-cluster methodology (CCSD(T)), and critically correlated with the experimental data. It is argued that whereas the bonding of NO to Co(II) porphyrin is a simple radical recombination, the bonding of NO to Mn(II) porphyrin is accompanied by a crossing of spin states. For this reason, the spin-state conversion energy contributes to the Mn-NO bond energy, and the paradigmatic correlation between bond length and bond energy is violated for the considered nitrosyl complexes: the Mn-NO bond is (structurally) shorter by ∼0.2 Å, albeit (energetically) weaker by a few kcal/mol, compared with the Co-NO bond. Moreover, none of the many tested DFT methods can reproduce the Co-NO and Mn-NO bond energies simultaneously, except for calculations with B3LYP*-D3, TPSSh-D3, and M06-D3 methods supplemented with the proposed spin-state energy correction (to compensate for an error on the calculated spin-state conversion energy). The results of this study are important to appreciate the role of spin-state changes in ligand binding properties of heme-related models. They also highlight the need for accurate calculations for correct interpretation of experimental data, including the qualitative structure-energy relationship. PMID:26000802

  18. Synthesis, structure and magnetic properties of cobalt(II) and copper(II) coordination polymers assembled by phthalate and 4-methylimidazole

    NASA Astrophysics Data System (ADS)

    Baca, Svetlana G.; Malinovskii, Stanislav T.; Franz, Patrick; Ambrus, Christina; Stoeckli-Evans, Helen; Gerbeleu, Nicolae; Decurtins, Silvio

    2004-08-01

    New coordination polymers [ M(Pht)(4-MeIm) 2(H 2O)] n ( M=Co ( 1), Cu ( 2); Pht 2-=dianion of o-phthalic acid; 4-MeIm=4-methylimidazole) have been synthesized and characterized by IR spectroscopy, X-ray crystallography, thermogravimetric analysis and magnetic measurements. The crystal structures of 1 and 2 are isostructural and consist of [ M(4-MeIm) 2(H 2O)] building units linked in infinite 1D helical chains by 1,6-bridging phthalate ions which also act as chelating ligands through two O atoms from one carboxylate group in the case of 1. In complex 1, each Co(II) atom adopts a distorted octahedral N 2O 4 geometry being coordinated by two N atoms from two 4-MeIm, three O atoms of two phthalate residues and one O atom of a water molecule, whereas the square-pyramidal N 2O 3 coordination of the Cu(II) atom in 2 includes two N atoms of N-containing ligands, two O atoms of two carboxylate groups from different Pht, and a water molecule. An additional strong O-H⋯O hydrogen bond between a carboxylate group of the phthalate ligand and a coordinated water molecule join the 1D helical chains to form a 2D network in both compounds. The thermal dependences of the magnetic susceptibilities of the polymeric helical Co(II) chain compound 1 were simulated within the temperature range 20-300 K as a single ion case, whereas for the Cu(II) compound 2, the simulations between 25 and 300 K, were made for a linear chain using the Bonner-Fisher approximation. Modelling the experimental data of compound 1 with MAGPACK resulted in: g=2.6, | D|=62 cm -1. Calculations using the Bonner-Fisher approximation gave the following result for compound 2: g=2.18, J=-0.4 cm -1.

  19. Magnetic structure and dynamics of a strongly one-dimensional cobaltII metal-organic framework

    NASA Astrophysics Data System (ADS)

    Sibille, Romain; Lhotel, Elsa; Mazet, Thomas; Malaman, Bernard; Ritter, Clemens; Ban, Voraksmy; François, Michel

    2014-03-01

    We investigate the magnetism of the CoII4(OH)2(C10H16O4)3 metal-organic framework, which displays complex inorganic chains separated from each other by distances of 1 to 2 nm and orders at 5.4 K. The zero-field magnetic structure is determined using neutron powder diffraction: it is mainly antiferromagnetic but possesses a ferromagnetic component along the c axis. This magnetic structure persists in presence of a magnetic field. Alternating current susceptibility measurements confirm the existence of a single thermally activated regime over seven decades in frequency (E /kB≈64 K), whereas time-dependent relaxation of the magnetization after saturation in an external field leads to a two times smaller energy barrier. These experiments probe the slow dynamics of domain walls within the chains: we propose that the ac measurements are sensitive to the motion of existing domain walls within the chains, while the magnetization measurements are governed by the creation of domain walls.

  20. Tetra­aqua­bis­(piperazin-1-ium)cobalt(II) bis­(sulfate) dihydrate

    PubMed Central

    Sahbani, Thameur; Smirani Sta, Wajda; Rzaigui, Mohamed

    2013-01-01

    In the centrosymmetric title compound, [Co(C4H11N2)2(H2O)4](SO4)2·2H2O, the CoII atom is coordinated in a distorted octa­hedral geometry by four water O atoms and two piperazinium N atoms. These four water O atoms define an equatorial plane with a maximum deviation of 0.0384 (1) Å while the two piperazinium N atoms complete the octa­hedron in the axial positions. Neighboring complex mol­ecules and sulfate anions are connected through an extensive network of N—H⋯O and O—H⋯O hydrogen bonds, which link the different chemical species into layers in the ab plane. Additional Owater—H⋯O hydrogen bonds involving the non-coordinating water mol­ecules and C—H⋯O inter­actions connect these layers into a three-dimensional supra­molecular structure. PMID:24454163

  1. Two Dawson-templated three-dimensional metal-organic frameworks based on oxalate-bridged binuclear cobalt(II)/Nickel(II) SBUs and Bpy linkers.

    PubMed

    Zhao, Xinyu; Liang, Dadong; Liu, Shuxia; Sun, Chunyan; Cao, Ruige; Gao, Chaoying; Ren, Yuanhang; Su, Zhongmin

    2008-08-18

    The Dawson anion P 2W 18O 62 (6-) has been used as a noncoordinating polyoxoanion template for the construction of two metal-organic frameworks, namely, [M 2(bpy) 3(H 2O) 2(ox)][P 2W 18O 62]2(H 2-bpy). nH 2O (M = Co(II), n = 3 ( 1); M = Ni(II), n = 2 ( 2)) (bpy = 4,4'-bipyridine; ox = C 2O 4 (2-)). Single-crystal X-ray analysis reveals that both of the structures exhibit 3D host frameworks constructed from the oxalate-bridged binuclear superoctahedron secondary building units (SBUs) and bpy linkers and the voids of which are occupied by Dawson anions, guest bpy, and water molecules. Magnetic studies reveal that there are antiferromagnetic exchange interactions among the transition-metal centers in compounds 1 and 2. Furthermore, a compound 1-modified carbon paste electrode ( 1-CPE) displays good electrocatalytic activity toward the reduction of nitrite. PMID:18620386

  2. 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.

  3. 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.

  4. 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.

  5. 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. PMID:21748828

  6. Bis(2-meth­oxy­benzyl­ammonium) di­aqua­bis­(di­hydrogen diphosphato-κ2 O,O′)cobaltate(II) dihydrate

    PubMed Central

    Elboulali, Adel; Selmi, Ahmed; Ratel-Ramond, Nicolas; Rzaigui, Mohamed; Akriche, Samah Toumi

    2014-01-01

    The title compound, (C8H12NO)2[Co(H2P2O7)2(H2O)2]·2H2O, crystallizes isotypically with its MnII analogue. It consists of alternating layers of organic cations and inorganic complex anions, extending parallel to (100). The complex cobaltate(II) anion exhibits -1 symmetry. Its Co2+ atom has an octa­hedral coordination sphere, defined by two water mol­ecules in apical positions and two H2P2O7 2− ligands in equatorial positions. The cohesion between inorganic and organic layers is accomplished by a set of O—H⋯O and N—H⋯O hydrogen bonds involving the organic cation, the inorganic anion and the remaining lattice water mol­ecules. PMID:24826105

  7. Comparison of technetium-99m-HM-PAO leukocytes with indium-111-oxine leukocytes for localizing intraabdominal sepsis

    SciTech Connect

    Mountford, P.J.; Kettle, A.G.; O'Doherty, M.J.; Coakley, A.J. )

    1990-03-01

    Technetium-99m-HM-PAO (({sup 99m}Tc)HM-PAO) leukocyte and indium-111-oxine (111In-oxine) leukocyte scanning were carried out simultaneously in 41 patients at 4 hr and 24 hr after reinjection to determine whether the 4-hr {sup 99m}Tc scan could replace the 24-hr {sup 111}In scan for detecting intraabdominal sepsis. Abdominal infection was confirmed in 12 cases. The 4-hr {sup 99}Tc-leukocyte scan, the 4-hr {sup 111}In-leukocyte scan, and the 24-hr {sup 111}In-leukocyte scan yielded a sensitivity of 100%, 67%, and 100%, respectively, and a specificity of 62%, 90%, and 86%, respectively. The 24-hr {sup 99m}Tc-leukocyte scan also produced a sensitivity of 100%, but it was falsely positive in all 29 cases without infection due to physiologic bowel uptake. False-positive 4-hr {sup 99m}Tc-leukocyte scans were also produced by physiologic bowel uptake in seven cases all of whom had true-negative 4-hr and 24-hr {sup 111}In-leukocyte scans. Because of the high incidence of false-positive 4-hr ({sup 99m}Tc)HM-PAO leukocyte scans, it was concluded that they could not replace 24-hr {sup 111}In-leukocyte scans for detecting intraabdominal sepsis, and that serial {sup 99m}Tc leukocyte scans starting earlier than 4 hr after reinjection must be evaluated.

  8. 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. PMID:24007993

  9. Characterization of exposures among cemented tungsten carbide workers. Part II: Assessment of surface contamination and skin exposures to cobalt, chromium and nickel.

    PubMed

    Day, Gregory A; Virji, M Abbas; Stefaniak, Aleksandr B

    2009-05-01

    Cobalt, chromium and nickel are among the most commonly encountered contact allergens in the workplace, all used in the production of cemented tungsten carbides (CTC). Exposures to these metal-containing dusts are frequently associated with skin sensitization and/or development of occupational asthma. The objectives of this study were to assess the levels of cobalt, chromium and nickel on work surfaces and on workers' skin in three CTC production facilities. At least one worker in each of 26 work areas (among all facilities) provided hand and neck wipe samples. Wipe samples were also collected from work surfaces frequently contacted by the 41 participating workers. Results indicated that all surfaces in all work areas were contaminated with cobalt and nickel, with geometric means (GMs) ranging from 4.1 to 3057 microg/100 cm(2) and 1.1-185 microg/100 cm(2), respectively; most surfaces were contaminated with chromium (GM=0.36-67 microg/100 cm(2)). The highest GM levels of all metals were found on control panels, containers and hand tools, whereas lowest levels were on office and telecommunication equipment. The highest GM levels of cobalt and nickel on skin were observed among workers in the powder-handling facility (hands: 388 and 24 microg; necks: 55 and 6 microg, respectively). Levels of chromium on workers' skin were generally low among all facilities. Geometric standard deviations associated with surface and skin wipe measurements among work areas were highly variable. Exposure assessment indicated widespread contamination of multiple sensitizing metals in these three facilities, suggesting potential transfer of contaminants from surfaces to skin. Specific action, including improved housekeeping and training workers on appropriate use and care of personal protective equipment, should be implemented to reduce pathways of skin exposure. Epidemiologic studies of associated adverse health effects will likely require more biologically relevant exposure metrics to

  10. Cobalt single-molecule magnet

    NASA Astrophysics Data System (ADS)

    Yang, En-Che; Hendrickson, David N.; Wernsdorfer, Wolfgang; Nakano, Motohiro; Zakharov, Lev N.; Sommer, Roger D.; Rheingold, Arnold L.; Ledezma-Gairaud, Marisol; Christou, George

    2002-05-01

    A cobalt molecule that functions as a single-molecule magnet, [Co4(hmp)4(MeOH)4Cl4], where hmp- is the anion of hydroxymethylpyridine, is reported. The core of the molecule consists of four Co(II) cations and four hmp- oxygen atom ions at the corners of a cube. Variable-field and variable-temperature magnetization data have been analyzed to establish that the molecule has a S=6 ground state with considerable negative magnetoanisotropy. Single-ion zero-field interactions (DSz2) at each cobalt ion are the origin of the negative magnetoanisotropy. A single crystal of the compound was studied by means of a micro-superconducting quantum interference device magnetometer in the range of 0.040-1.0 K. Hysteresis was found in the magnetization versus magnetic field response of this single crystal.

  11. Crystal structure of the salt bis-(tri-ethano-lamine-κ(3) N,O,O')cobalt(II) bis-[2-(2-oxo-2,3-di-hydro-1,3-benzo-thia-zol-3-yl)acetate].

    PubMed

    Ashurov, Jamshid M; Obidova, Nodira J; Abdireymov, Hudaybergen B; Ibragimov, Bakhtiyar T

    2016-03-01

    The reaction of 2-(2-oxo-2,3-di-hydro-1,3-benzo-thia-zol-3-yl)acetic acid (NBTA) and tri-ethano-lamine (TEA) with Co(NO3)2 results in the formation of the title complex, [Co(C6H15NO3)2](C9H6NO3S)2, which is formed as a result of the association of bis-(tri-ethano-lamine)-cobalt(II) and 2-(2-oxo-2,3-di-hydro-1,3-benzo-thia-zol-3-yl)acetate units. It crystallizes in the monoclinic centrosymmetric space group P21/c, with the Co(II) ion situated on an inversion centre. In the complex cation, the Co(II) ion is octa-hedrally coordinated by two N,O,O'-tridentate TEA mol-ecules with a facial distribution and the N atoms in a trans arrangement. Two ethanol groups of each TEA mol-ecule form two five-membered chelate rings around the Co(II) ion, while the third ethanol group does not coordinate to the metal. The free and coordinating hy-droxy groups of the TEA mol-ecules are involved in hydrogen bonding with the O atoms of NBTA anions, forming an infinite two-dimensional network extending parallel to the bc plane. PMID:27006821

  12. Complete cobalt recovery from lithium cobalt oxide in self-driven microbial fuel cell - Microbial electrolysis cell systems

    NASA Astrophysics Data System (ADS)

    Huang, Liping; Yao, Binglin; Wu, Dan; Quan, Xie

    2014-08-01

    Complete cobalt recovery from lithium cobalt oxide requires to firstly leach cobalt from particles LiCoO2 and then recover cobalt from aqueous Co(II). A self-driven microbial fuel cell (MFC)-microbial electrolysis cell (MEC) system can completely carry out these two processes, in which Co(II) is firstly released from particles LiCoO2 on the cathodes of MFCs and then reduced on the cathodes of MECs which are powered by the cobalt leaching MFCs. A cobalt leaching rate of 46 ± 2 mg L-1 h-1 with yield of 1.5 ± 0.1 g Co g-1 COD (MFCs) and a Co(II) reduction rate of 7 ± 0 mg L-1 h-1 with yield of 0.8 ± 0.0 g Co g-1 COD (MECs), as well as a overall system cobalt yield of 0.15 ± 0.01 g Co g-1 Co can be achieved in this self-driven MFC-MEC system. Coulombic efficiencies reach 41 ± 1% (anodic MFCs), 75 ± 0% (anodic MECs), 100 ± 2% (cathodic MFCs), and 29 ± 1% (cathodic MECs) whereas overall system efficiency averages 34 ± 1%. These results provide a new process of linking MFCs to MECs for complete recovery of cobalt and recycle of spent lithium ion batteries with no external energy consumption.

  13. Bis(μ2-benzoato-κ2 O:O′)bis­[(benzoato-κ2 O,O′)bis(4,4′-bi­pyridine-κN)cobalt(II)]–benzoic acid (1/6)

    PubMed Central

    Peña-Rodríguez, Rodolfo; Rivera, José María; Colorado-Peralta, Raúl; Duarte-Hernández, Angélica María; Flores-Parra, Angelina

    2014-01-01

    In the title compound, [Co2(C7H5O2)4(C10H8N2)4]·6C6H5COOH, the centrosymmetric cobalt dimer co-crystallizes with six mol­ecules of benzoic acid. Each CoII atom is coordinated by four O atoms in a distorted square-planar arrangement while the N atoms are located in apical positions. The dihedral angles between the rings comprising each of the 4,4′-bipyridyl ligands are 25.2 (2) and 22.8 (2)°. In the crystal, the three-dimensional network is assembled by O—H⋯O and C—H⋯O hydrogen bonds. PMID:24526949

  14. Bis(μ2-benzoato-κ(2) O:O')bis-[(benzoato-κ(2) O,O')bis(4,4'-bi-pyridine-κN)cobalt(II)]-benzoic acid (1/6).

    PubMed

    Peña-Rodríguez, Rodolfo; Rivera, José María; Colorado-Peralta, Raúl; Duarte-Hernández, Angélica María; Flores-Parra, Angelina

    2014-01-01

    In the title compound, [Co2(C7H5O2)4(C10H8N2)4]·6C6H5COOH, the centrosymmetric cobalt dimer co-crystallizes with six mol-ecules of benzoic acid. Each Co(II) atom is coordinated by four O atoms in a distorted square-planar arrangement while the N atoms are located in apical positions. The dihedral angles between the rings comprising each of the 4,4'-bipyridyl ligands are 25.2 (2) and 22.8 (2)°. In the crystal, the three-dimensional network is assembled by O-H⋯O and C-H⋯O hydrogen bonds. PMID:24526949

  15. Solubility of cobalt in cement.

    PubMed

    Fregert, S; Gruvberger, B

    1978-02-01

    Unlike chromate, cobalt occurring as cobalt oxides in cement is not water-soluble in a detectable amount. Cobalt oxides are to some extent soluble in the presence of amino acids with which cobalt forms complexes. Such complexes can elicit patch test reactions. It is postulated that cobalt is more readily dissolved by forming complexes in eczematous skin than in normal skin. This may explain why cobalt sensitization in cement eczemas is secondary to chromate sensitivity. PMID:657784

  16. 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.

  17. 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.

  18. 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).

  19. 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.

  20. 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.

  1. 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.

  2. First-principles study of energetic complexes (II): (5-cyanotetrazolato-N2) pentaammine cobalt (III) perchlorate (CP) and Ni, Fe and Zn analogues.

    PubMed

    Shang, Jing; Zhang, Jian-Guo; Zhang, Tong-Lai; Huang, Hui-Sheng; Zhang, Shao-Wen; Zhou, Zun-Ning

    2012-06-01

    First-principles methods using the TPSS density functional level of theory with the basis set 6-31G** were applied to study (5-cyanotetrazolato-N(2)) pentaammine cobalt (III) perchlorate (CP) and Ni, Fe and Zn analogues in the gas phase. The optimized lowest-energy geometry of CP was calculated from reported experimental structural data using the TPSS method. The calculated values are in good agreement with those measured by X-ray diffraction. Ni, Fe and Zn analogues were constructed and calculated on the same basis. NBO results showed that the metal-ligand interactions have covalent character. Donor-acceptor analyses predicted that the delocalization energy E(2) decreases from Co to Zn, so the covalent nature of the complexes increases in the order Co>Fe>Ni>Zn. In addition, HOMO-LUMO composition was investigated to determine the stability of the title compounds. PMID:22127608

  3. Dichlorido(2-chloro-9-mesityl-1,10-phenanthroline-κ2 N,N′)cobalt(II) dichloro­methane hemisolvate

    PubMed Central

    Yang, Yue; Yang, Peiju; Zhang, Cui; Wu, Biao

    2008-01-01

    The title compound, [CoCl2(C21H17ClN2)]·0.5CH2Cl2, crystallizes from dichloro­methane as a 2:1 solvate [CoCl2L]2·CH2Cl2 (L is 2-chloro-9-mesityl-1,10-phenanthroline). There are two independent CoCl2 L mol­ecules in the asymmetric unit and both mol­ecules have similar conformations. They are connected by a weak C—H⋯π inter­action involving the mesityl ring. The cobalt center is four-coordinated by the two N-atom donors of the bidentate ligand and two chloride ions in a distorted tetra­hedral geometry. The packing of the mol­ecules is stabilized by weak slipped π–π stacking inter­actions between symmetry-related phenanthroline groups. PMID:21202178

  4. 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.

  5. 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.

  6. Cobalt(II) metal-organic framework micro-nanoparticles: Molecular self-assembly from layers to micropores showing the conjunctive orientation of carboxyl groups

    NASA Astrophysics Data System (ADS)

    Ye, Jing; Li, Xiaoqi; Xu, Zhen-liang; Xu, Haitao

    2015-08-01

    Cobalt metal-organic framework (MOF) materials CoL(1,4-chdc)·mH2O (1,4-chdc = 1,4-cyclohexanedicarboxylic acid, L1 = 1,2-di(4-pyridyl)ethylene, and m = 0 for 1Co; L2 = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene and m = 2 for 2Co) were assembled in a MeOH-H2O solvent system. They crystallized in a monoclinic system with space group P2(1)/c, Z = 4, a = 9.479(4) Å, b = 13.704(6) Å, c = 14.455(6) Å, and β = 99.424(6)° for 1Co, and a = 14.349(11) Å, b = 12.088(9) Å, c = 26.62(2) Å, and β = 97.255(11)° for 2Co. It was shown that N-ligand can regulate and control the conjunctive orientation of carboxyl groups in these MOFs; thus, the MOFs exhibited structures that ranged from layers to micropores. Furthermore, the micro-nanoparticles of 1Co and 2Co were investigated for new potential applications of micro-nano MOFs.

  7. 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.

  8. Enhanced third-order nonlinear optical properties determined in thin films using the Z-scan technique: bis(μ-4,4'-oxydibenzoato)bis[(4'-phenyl-2,2':6',2''-terpyridine)cobalt(II)].

    PubMed

    Liu, Runqiang; Zhao, Ning; Liu, Ping; An, Caixia; Lian, Zhaoxun

    2016-05-01

    π-Conjugated organic materials exhibit high and tunable nonlinear optical (NLO) properties, and fast response times. 4'-Phenyl-2,2':6',2''-terpyridine (PTP) is an important N-heterocyclic ligand involving π-conjugated systems, however, studies concerning the third-order NLO properties of terpyridine transition metal complexes are limited. The title binuclear terpyridine Co(II) complex, bis(μ-4,4'-oxydibenzoato)-κ(3)O,O':O'';κ(3)O'':O,O'-bis[(4'-phenyl-2,2':6',2''-terpyridine-κ(3)N,N',N'')cobalt(II)], [Co2(C14H8O5)2(C21H15N3)2], (1), has been synthesized under hydrothermal conditions. In the crystal structure, each Co(II) cation is surrounded by three N atoms of a PTP ligand and three O atoms, two from a bidentate and one from a symmetry-related monodentate 4,4'-oxydibenzoate (ODA(2-)) ligand, completing a distorted octahedral coordination geometry. Neighbouring [Co(PTP)](2+) units are bridged by ODA(2-) ligands to form a ring-like structure. The third-order nonlinear optical (NLO) properties of (1) and PTP were determined in thin films using the Z-scan technique. The title compound shows a strong third-order NLO saturable absorption (SA), while PTP exhibits a third-order NLO reverse saturable absorption (RSA). The absorptive coefficient β of (1) is -37.3 × 10(-7) m W(-1), which is larger than that (8.96 × 10(-7) m W(-1)) of PTP. The third-order NLO susceptibility χ((3)) values are calculated as 6.01 × 10(-8) e.s.u. for (1) and 1.44 × 10(-8) e.s.u. for PTP. PMID:27146576

  9. 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

  10. 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.

  11. 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.

  12. 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).

  13. 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).

  14. Crystal structure of di-aqua-bis-(4-tert-butyl-benzoato-κO)bis-(nicotinamide-κN (1))cobalt(II) dihydrate.

    PubMed

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

    2016-07-01

    The asymmetric unit of the mononuclear cobalt complex, [Co(C11H13O2)2(C6H6N2O)2(H2O)2]·2H2O, contains one half of the complex mol-ecule, one coordinating and one non-coordinating water mol-ecule, one 4-tert-butyl-benzoate (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 octa-hedral coordination completed by the two pyridine N atoms of the NA ligands at distances of 2.1638 (11) Å. The coordinating water mol-ecules are hydrogen bonded to the carboxyl O atoms [O ⋯ O = 2.6230 (17) Å], enclosing an S(6) hydrogen-bonding motif, while inter-molecular O-H⋯O hydrogen bonds link two of the non-coordinating water mol-ecules to the coordinating water mol-ecules and NA anions. The dihedral angle between the planar carboxyl-ate 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 mol-ecules, 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

  15. Mixed-ligand cobalt(II) complexes of bioinorganic and medicinal relevance, involving dehydroacetic acid and β-diketones: Their synthesis, hyphenated experimental-DFT, thermal and bactericidal facets

    NASA Astrophysics Data System (ADS)

    Maurya, R. C.; Malik, B. A.; Mir, J. M.; Vishwakarma, P. K.; Rajak, D. K.; Jain, N.

    2015-11-01

    The present report pertains to synthesis and combined experimental-DFT studies of a series of four novel mixed-ligand complexes of cobalt(II) of the general composition [Co(dha)(L)(H2O)2], where dhaH = dehydroacetic acid, LH = β-ketoenolates viz., o-acetoacetotoluidide (o-aatdH), o-acetoacetanisidide (o-aansH), acetylacetone (acacH) or 1-benzoylacetone (1-bac). The resulting complexes were formulated based on elemental analysis, molar conductance, magnetic measurements, mass spectrometric, IR, electronic, electron spin resonance and cyclic voltammetric studies. The TGA based thermal behavior of one representative complex was evaluated. Molecular geometry optimizations and vibrational frequency calculations have been performed with Gaussian 09 software package by using density functional theory (DFT) methods with B3LYP/LANL2MB combination for dhaH and one of its complexes, [Co(dha)(1-bac)(H2O)2]. Theoretical data has been found in an excellent agreement with the experimental results. Based on experimental and theoretical data, suitable trans-octahedral structure has been proposed for the present class of complexes. Moreover, the complexes also showed a satisfactory antibacterial activity.

  16. Wrought cobalt- base superalloys

    NASA Astrophysics Data System (ADS)

    Klarstrom, D. L.

    1993-08-01

    Wrought cobalt-base superalloys are used extensively in gas turbine engines because of their excellent high-temperature creep and fatigue strengths and resistance to hot corrosion attack. In addition, the unique character of the oxide scales that form on some of the alloys provides outstanding resistance to high-temperature sliding wear. This article provides a review of the evolutionary development of wrought cobalt-base alloys in terms of alloy design and physical metallurgy. The topics include solid-so-lution strengthening, carbide precipitation characteristics, and attempts to introduce age hardening. The use of PHACOMP to enhance thermal stability characteristics and the incorporation of rare-earth ele-ments to improve oxidation resistance is also reviewed and discussed. The further development of cobalt-base superalloys has been severely hampered by past political events, which have accentuated the strategic vulnerability of cobalt as a base or as an alloying element. Consequently, alternative alloys have been developed that use little or no cobalt. One such alternative, Haynes® 230TMalloy, is discussed briefly.

  17. Crystal structure of poly[{μ-N,N′-bis[(pyridin-4-yl)meth­yl]oxalamide}-μ-oxalato-cobalt(II)

    PubMed Central

    Zou, Hengye; Qi, Yanjuan

    2014-01-01

    In the polymeric title compound, [Co(C2O4)(C14H14N4O2)]n, the CoII atom is six-coordinated by two N atoms from symmetry-related bis­[(pyridin-4-yl)meth­yl]oxalamide (BPMO) ligands and four O atoms from two centrosymmetric oxalate anions in a distorted octa­hedral coordination geometry. The CoII atoms are linked by the oxalate anions into a chain running parallel to [100]. The chains are linked by the BPMO ligands into a three-dimensional architecture. In addition, N—H⋯O hydrogen bonds stabilize the crystal packing. PMID:25309173

  18. Bis(N,N′-dimethyl­ethylenediammonium) tris­(oxalato-κ2 O 1,O 2)cobaltate(II) dihydrate: an ion-pair complex

    PubMed Central

    Gaye, Papa Aly; Sy, Adama; Thiam, Ibrahima Elhadj; Gaye, Mohamed; Retailleau, Pascal

    2011-01-01

    The CoII ion in the title complex, (C4H14N2)2[Co(C2O4)3]·2H2O, is coordinated by three oxalate ions, resulting in a distorted octa­hedral geometry. Two uncoordinated water mol­ecules are present in asymmetric unit. Inter­molecular N—H⋯O and O—H⋯O hydrogen bonds between the different entities stabilize the crystal structure. PMID:22058871

  19. 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

  20. 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. PMID:25469667

  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. Kinetics and sites of destruction of /sup 111/In-oxine-labeled platelets in idiopathic thrombocytopenic purpura: a quantitative study

    SciTech Connect

    Heyns, A.D.; Loetter, M.G.; Badenhorst, P.N.; de Kock, F.; Pieters, H.; Herbst, C.; van Reenen, O.R.; Kotze, H.; Minnaar, P.C.

    1982-04-01

    Kinetics and quantification of the sites of destruction of /sup 111/In-oxine-labeled autologous platelets were investigated in eight patients with idiopathic thrombocytopenic purpura. The mean platelet count was 17 +/- 9 X 10(9)/liter; platelets were separated by differential centrifugation and labeled with 5.6 +/- 2.5 MBq /sup 111/In. Whole body and organ /sup 111/In-platelet distribution was quantitated with a scintillation camera and a computer-assisted imaging system acquisition matrix. Areas of interest were selected with the computer and organ /sup 111/In-radioactivity expressed as a percentage of whole body activity. Mean platelet survival was 49.5 +/- 29.6 hr and the survival curves were exponential. Equilibrium percentage organ /sup 111/In-radioactivity was (normal values in parentheses): spleen 33.7 +/- 8.8 (31.1 +/- 10.2); liver 16.1 +/- 9.5 (13.1 +/- 1.3); thorax 22.8 +/- 3.7 (28.2 +/- 5.6). Percentage organ /sup 111/In-activity at the time when labeled platelets had disappeared from the circulation was: spleen 44.5 +/- 16.4 (40 +/- 16); liver 16.0 +/- 11.5 (32.4 +/- 7.2); thorax 19.7 +/- 6.0 (17.7 +/- 10.3). Thorax activity corresponds to bone marrow radioactivity. Three patterns of platelet sequestration were evident. Three patients had mainly splenic sequestration, two mainly hepatic sequestration, and three diffuse reticuloendothelial system sequestration with a major component of platelets destroyed in the bone marrow. Splenectomy was performed in two patients. The pattern of /sup 111/In-platelet sequestration was not predictive of response of glucocorticoid therapy or indicative of the necessity for splenectomy. Quantitative /sup 111/In-labeled autologous platelet kinetic studies provide a new tool for the investigation of platelet disorders.U

  3. The development of a sampler-sensor using a vanadium-oxinate-polymer film for the selective and direct determination of atmospheric ethanol.

    PubMed

    Hayes, E T; Galal, A; Mark, H B

    1995-06-01

    The development of a sensor for the direct and selective determination of atmospheric ethanol is in the initial stages. The sensor takes advantage of the selective chemical reaction between ethanol and vanadium oxinate. This reaction occurs in an organic medium where a red colored complex is the product. This reaction is determined spectrophotometrically where the absorbance maxima is 475 nm. The focus of this paper is to discuss the parameters necessary to develop a solid sorbent sampling-sensor which can be used to determine atmospheric ethanol. PMID:18966304

  4. (Acetato-κ2 O,O′)(acetato-κO)bis(2-amino-3-methyl­pyridine-κN 1)cobalt(II)

    PubMed Central

    Tadjarodi, Azadeh; Bijanzad, Keyvan; Notash, Behrouz

    2012-01-01

    In the title compound, [Co(CH3COO)2(C6H8N2)2], the CoII ion is five-coordinated by two pyridine N atoms from two 2-amino-3-methyl­pyridine ligands, two O atoms from one acetate ion and one O atom from another acetate ion in a distorted trigonal–bipyramidal geometry. The pyridine rings are nearly perpendicular to each other [dihedral angle = 84.49 (16)°]. The crystal packing is stabilized by intra­molecular and inter­molecular N—H⋯O hydrogen-bonding inter­actions. PMID:23125590

  5. Tetra­kis(ethyl pyridine-4-carboxyl­ate-κN)bis­(thio­cyanato-κN)cobalt(II)

    PubMed Central

    Feng, Xiu-Ling; Zhang, Yu-Ping

    2012-01-01

    In the title complex, [Co(NCS)2(C8H9NO2)4], the CoII atom is six-coordinated by four N atoms from four ethyl pyridine-4-carboxyl­ate ligands in the equatorial plane and two N atoms of thio­cyanate ligands in the axial positions, showing a slightly distorted octa­hedral geometry. The structure exhibits disorder in one of the ethyl chains, which was refined using a two-site model with 0.70 (6):0.30 (6) occupancy. PMID:22719337

  6. 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.

  7. Crystal structure of tetra-kis-(isonicotinamide-κN)bis-(thio-cyanato-κN)cobalt(II)-isonicotinamide-ethanol (1/2/1).

    PubMed

    Neumann, Tristan; Jess, Inke; Näther, Christian

    2016-08-01

    The asymmetric unit of the title compound, [Co(NCS)2(C6H6N2O)4]·2C6H6N2O·C2H5OH, comprises one Co(II) cation, two thio-cyanate anions, four coordinating and two solvent isonicotinamide molecules and one ethanol solvent mol-ecule. The Co(II) cations are octa-hedrally coordinated by four N-coordinating isonicotinamide ligands and two terminally N-bonded thio-cyanate anions. These discrete complexes are linked by inter-molecular N-H⋯O and N-H⋯S hydrogen-bonding inter-actions into a three-dimensional network. The two isonicotinamide and the ethanol solvent mol-ecules 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 mol-ecule is disordered over two sets of sites (occupancy ratio 0.6:0.4). PMID:27536386

  8. Diaqua­bis­(2-iodo­benzoato-κO)bis­(nicotinamide-κN 1)cobalt(II)

    PubMed Central

    Aydın, Ömür; Çaylak Delibaş, Nagihan; Necefoğlu, Hacali; Hökelek, Tuncer

    2012-01-01

    In the title complex, [Co(C7H4IO2)2(C6H6N2O)2(H2O)2], the CoII cation is located on an inversion center and is coordinated by two monodentate 2-iodo­benzoate (IB) anions, two nicotin­amide (NA) ligands and two water mol­ecules. The four O atoms in the equatorial plane around the CoII cation form a slightly distorted square-planar arrangement, while the slightly distorted octa­hedral coordination is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxyl­ate group and the adjacent benzene ring is 22.3 (3)°, while the pyridine ring and the benzene ring are oriented at a dihedral angle of 84.59 (13)°. Intra­molecular O—H⋯O hydrogen bonding occurs between the carboxyl­ate group and coordinated water mol­ecule. In the crystal, N—H⋯O, O—H⋯O and weak C—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional supra­molecular network. PMID:22589871

  9. Diaqua­bis­(2-chloro­benzoato-κO)bis­(nicotinamide-κN 1)cobalt(II)

    PubMed Central

    Dincel, Öznur; Tercan, Barış; Öztürkkan, Füreya Elif; Necefoğlu, Hacali; Hökelek, Tuncer

    2013-01-01

    In the title complex, [Co(C7H4ClO2)2(C6H6N2O)2(H2O)2], the CoII cation is located on an inversion center and is coord­inated by two 2-chloro­benzoate anions, two nicotin­amide (NA) ligands and two water mol­ecules. The four O atoms in the equatorial plane around the CoII cation form a slightly distorted square-planar arrangement, while the slightly distorted octa­hedral coordination is completed by the two pyridine N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxyl­ate group and the adjacent benzene ring is 29.7 (4)°, while the pyridine and benzene rings are oriented at a dihedral angle of 83.17 (15)°. Intra­molecular O—H⋯O hydrogen bonding occurs between the carboxyl­ate group and coordinating water mol­ecule. In the crystal, inter­molecular N—H⋯O, O—H⋯O and weak C—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional network. PMID:23476513

  10. Poly[[diaqua­bis­(μ2-4,4′-bipyrid­yl)cobalt(II)] dinitrate tetra­hydrate

    PubMed Central

    Lehleh, Asma; Boutebdja, Mehdi; Beghidja, Adel; Beghidja, Chahrazed; Merazig, Hocine

    2013-01-01

    The title compound, {[Co(C10H8N2)2(H2O)2](NO3)2·4H2O}n, (C10H8N2 = 4,4′-bipyridine = 4,4′-bpy) is a layered coordination polymer built up from a cationic square grid extending in (101) enclosing uncoordinating nitrate ions and water mol­ecules. The CoII ion has site symmetry 2 and one of the 4,4′-bpy ligands is generated by twofold symmetry [two N atoms and two C atoms lie on the rotation axis and the dihedral angle between the pyridine rings is 45.66 (5)°]. The other 4,4′-bpy ligand is generated by a crystallographic inversion center. The CoII ion exhibits a slightly distorted octa­hedral coordination geometry defined by two O atoms of two coordinating water mol­ecules and four N atoms from four bridging 4,4′-bpy ligands. The structure is consolidated by O—H⋯O, C—H⋯O and C—H⋯N hydrogen bonds. PMID:23633984

  11. 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

  12. 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. PMID:18959951

  13. Two Polymorphic Forms of a Six-Coordinate Mononuclear Cobalt(II) Complex with Easy-Plane Anisotropy: Structural Features, Theoretical Calculations, and Field-Induced Slow Relaxation of the Magnetization.

    PubMed

    Roy, Subhadip; Oyarzabal, Itziar; Vallejo, Julia; Cano, Joan; Colacio, Enrique; Bauza, Antonio; Frontera, Antonio; Kirillov, Alexander M; Drew, Michael G B; Das, Subrata

    2016-09-01

    A mononuclear cobalt(II) complex [Co(3,5-dnb)2(py)2(H2O)2] {3,5-Hdnb = 3,5-dinitrobenzoic acid; py = pyridine} was isolated in two polymorphs, in space groups C2/c (1) and P21/c (2). Single-crystal X-ray diffraction analyses reveal that 1 and 2 are not isostructural in spite of having equal formulas and ligand connectivity. In both structures, the Co(II) centers adopt octahedral {CoN2O4} geometries filled by pairs of mutually trans terminal 3,5-dnb, py, and water ligands. However, the structures of 1 and 2 disclose distinct packing patterns driven by strong intermolecular O-H···O hydrogen bonds, leading to their 0D→2D (1) or 0D→1D (2) extension. The resulting two-dimensional layers and one-dimensional chains were topologically classified as the sql and 2C1 underlying nets, respectively. By means of DFT theoretical calculations, the energy variations between the polymorphs were estimated, and the binding energies associated with the noncovalent interactions observed in the crystal structures were also evaluated. The study of the direct-current magnetic properties, as well as ab initio calculations, reveal that both 1 and 2 present a strong easy-plane magnetic anisotropy (D > 0), which is larger for the latter polymorph (D is found to exhibit values between +58 and 117 cm(-1) depending on the method). Alternating current dynamic susceptibility measurements show that these polymorphs exhibit field-induced slow relaxation of the magnetization with Ueff values of 19.5 and 21.1 cm(-1) for 1 and 2, respectively. The analysis of the whole magnetic data allows the conclusion that the magnetization relaxation in these polymorphs mainly takes place through a virtual excited state (Raman process). It is worth noting that despite the notable difference between the supramolecular networks of 1 and 2, they exhibit almost identical magnetization dynamics. This fact suggests that the relaxation process is intramolecular in nature and that the virtual state involved in the

  14. Synthesis, characterization, biological activity, molecular modeling and docking studies of complexes 4-(4-hydroxy)-3-(2-pyrazine-2-carbonyl)hydrazonomethylphenyl-diazen-yl-benzenesulfonamide with manganese(II), cobalt(II), nickel(II), zinc(II) and cadmium(II)

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.; Zayed, Mohamed E.; Alharbi, Suliman A.; Ammar, Reda A. A.; Elhenawy, Ahmed

    2015-03-01

    A new series of complexes of 4-(4-hydroxy)-3-(2-pyrazine-2-carbonyl)hydrazonomethylphenyl-diazen-yl-benzenesulfonamide (HL) with Mn(II), Co(II), Ni(II), Zn(II) and Cd(II) have been prepared and characterized by different physical techniques. The IR spectra of the prepared complexes were suggested that the ligand behaves as a tri-dentate ligand through the carbonyl oxygen, azomethine nitrogen and phenolic oxygen atoms (ONO). Electronic spectra and magnetic susceptibility measurements reveal octahedral geometry for all complexes. The elemental analyses and mass spectral data have justified the ML2 composition of complexes. The EPR spectra of Mn(II), Co(II) and Ni(II) complexes support the mononuclear structure. The crystal field splitting, Racah repulsion and nephelauxetic parameters and determined from the electronic spectra of the complexes. Thermal properties and decomposition kinetics of all complexes are investigated. The geometry of the metal complexes has been optimized with the help of molecular modeling. The biological activity of these compounds against various fungi has been investigated.

  15. Countercation-sensitive electrochromism of cobalt hexacyanoferrate films

    SciTech Connect

    Kulesza, P.J.; Malik, M.A.; Miecznikowski, K.; Wolkiewicz, A.; Zamponi, S.; Berrettoni, M.; Marassi, R.

    1996-01-01

    Cobalt(II) hexacyanoferrate(III,II) a system analogous to prussian blue, is a unique electrochromic material: its color is not only dependent on the oxidation potential, but also on the nature of the countercations sorbed from electrolyte during reduction. The electrodeposition of cobalt hexacyanoferrate thin films, their voltammetric behavior and spectroelectrochemical identity are reported here in potassium and sodium electrolytes. The oxidized film is purple brown in both electrolytes, but following reduction, the system turns olive-brown in 1 M KCl and becomes green in 1 M NaCl.

  16. Mechanical properties of nanocrystalline cobalt

    NASA Astrophysics Data System (ADS)

    Karimpoor, Amir A.; Erb, Uwe

    2006-05-01

    Due to their excellent wear and corrosion properties, nanocrystalline cobalt and several cobalt alloys made by electrodeposition are currently being developed as environmentally benign replacement coatings for hard chromium electrodeposits. The focus of this study is on the mechanical properties of nanocrystalline cobalt, which are currently not well understood. A comparison is presented for hardness, tensile properties, Charpy impact properties and fracture surface analysis of both nanocrystalline (grain size: 12 nm) and conventional polycrystalline (grain size: 4.8 m) cobalt. It is shown that the hardness and tensile strength of nanocrystalline cobalt is 2-3 times higher than for polycrystalline cobalt. However, in contrast to other nanocrystalline materials tested previously, nanocrystalline cobalt retains considerable ductility with elongation to fracture values up to 7%.

  17. 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.

  18. 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.

  19. Slow magnetic relaxation in octahedral cobalt(II) field-induced single-ion magnet with positive axial and large rhombic anisotropy.

    PubMed

    Herchel, Radovan; Váhovská, Lucia; Potočňák, Ivan; Trávníček, Zdeněk

    2014-06-16

    Pseudooctahedral mononuclear cobat(II) complex [Co(abpt)2(tcm)2] (1), where abpt = 4-amino-3,5-bis(2-pyridyl)-1,2,4-triazole and tcm = tricyanomethanide anion, shows field-induced slow relaxation of magnetization with U = 86.2 K and large axial and rhombic single-ion zero-field-splitting parameters, D = +48(2) cm(-1) and E/D = 0.27(2) (D = +53.7 cm(-1) and E/D = 0.29 from ab initio CASSCF/NEVPT2 calculations), thus presenting a new example of a field-induced single-ion magnet with transversal magnetic anisotropy. PMID:24853769

  20. 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.

  1. 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.

  2. 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…

  3. Separation of cobalt from synthetic intermediate and decontamination radioactive wastes using polyurethane foam

    SciTech Connect

    Rao, S.V.S.; Lal, K.B.; Narasimhan, S.V.; Ahmed, J.

    1997-12-01

    Studies have been carried out on the removal of radioactive cobalt ({sup 60}Co) from synthetic intermediate level waste (ILW) and decontamination waste using neat polyurethane (PU) foam as well as n-tributyl phosphate-polyurethane (TBP-PU) foam. The radioactive cobalt has been extracted on the PU foam as cobalt thiocyanate from the ILW. Maximum removal of cobalt has been observed when the concentration of thiocyanate in the solution is about 0.4 M. Cobalt can be separated from decontamination waste containing ethylenediaminetetraacetic acid (EDTA) and iron(II). The extent of extraction of cobalt is slow and the separation of iron and cobalt is better with the neat PU foam compared to the TBP-PU foam. The presence of iron in the decontamination waste facilitates the extraction of cobalt thiocyanate on the PU foam. Column studies have been carried out in order to extend these studies to the plant scale. The capacities of the PU foams for cobalt have been determined. The effect of density and the surface area of PU foam have been investigated. Fourier Transform Infrared (FT-IR) spectral studies have been conducted to find out the interaction between PU foam and cobalt thiocyanate species.

  4. 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.

  5. Emission ((57)Co) Mössbauer spectroscopy as a tool for probing speciation and metabolic transformations of cobalt(II) in bacterial cells.

    PubMed

    Kamnev, Alexander A; Tugarova, Anna V; Kovács, Krisztina; Kuzmann, Ernő; Biró, Borbála; Tarantilis, Petros A; Homonnay, Zoltán

    2013-02-01

    The emission ((57)Co) variant of Mössbauer spectroscopy, rarely used in biology-related studies, was applied to study binding and possible transformations of (57)Co(II) traces in live and dead (hydrothermally treated) cells of the rhizobacterium Azospirillum brasilense (strain Sp7) at T=80 K in frozen aqueous suspensions and as their dried residues. The Mössbauer parameters calculated from the spectra were compared with the similarly obtained data reported earlier for another A. brasilense strain, Sp245 (which differs from strain Sp7 by the ecological niche occupied in the rhizosphere and was found earlier to exhibit different metabolic responses under similar environmental conditions). Similarly to strain Sp245, live cells of strain Sp7, rapidly frozen 2 min and 1 h after their contact with (57)Co(2+) (measured in frozen suspensions), showed marked differences in their Mössbauer parameters, reflecting metabolic transformations of (57)Co(2+) occurring within an hour. However, the parameters for strains Sp7 (this work) and Sp245 (reported earlier), obtained under similar conditions, were found to significantly differ, implying dissimilarity in their metabolic response to Co(2+). This is in line with their different metabolic responses to several heavy metals, including Co(2+), detected earlier using Fourier transform infrared spectroscopy. PMID:22960797

  6. 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). PMID:21864977

  7. 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. PMID:26379038

  8. 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

  9. A Photoinduced Cobalt-Catalyzed Synthesis of Pyrroles through in Situ-Generated Acylazirines.

    PubMed

    Pusch, Stefan; Kowalczyk, Danuta; Opatz, Till

    2016-05-20

    Tetrasubstituted pyrroles can be synthesized in a one-pot procedure from isoxazoles. The process includes the photoinduced in situ formation of acylazirines combined with a subsequent cobalt(II)-catalyzed ring expansion with 1,3-diketones. PMID:27081704

  10. Chalcogenide Cobalt telluride nanotubes

    NASA Astrophysics Data System (ADS)

    Dahal, Bishnu; Dulal, Rajendra; Pegg, Ian L.; Philip, John

    Cobalt telluride nanotubes are grown using wet chemical and hydrothermal syntheses. Wet chemical synthesized nanotubes display nearly 1: 1 Co to Te ratio. On the other hand, CoTe nanotubes synthesized using hydrothermal method show excess Co content leading to the compound Co58Te42. Both CoTe and Co58Te42 display magnetic properties, but with totally different characteristics. The Curie temperature of CoTe is higher than 400 K. However, the Tc of Co58Te42 is below 50 K. Transport properties of cobalt telluride (CoTe) nanotube devices show that they exhibit p-type semiconducting behavior. The magnetoresistance measured at 10 K show a magnetoresistance of 54%. . National Science Foundation under ECCS-0845501 and NSF-MRI, DMR-0922997.