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Sample records for ni complex cations

  1. Actinide cation-cation complexes

    International Nuclear Information System (INIS)

    Stoyer, N.J.; Seaborg, G.T.

    1994-12-01

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO 2 + ) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO 2 + ; therefore, cation-cation complexes indicate something unique about AnO 2 + cations compared to actinide cations in general. The first cation-cation complex, NpO 2 + ·UO 2 2+ , was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO 2 + species, the cation-cation complexes of NpO 2 + have been studied most extensively while the other actinides have not. The only PuO 2 + cation-cation complexes that have been studied are with Fe 3+ and Cr 3+ and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO 2 + ·UO 2 2+ , NpO 2 + ·Th 4+ , PuO 2 + ·UO 2 2+ , and PuO 2 + ·Th 4+ at an ionic strength of 6 M using LIPAS are 2.4 ± 0.2, 1.8 ± 0.9, 2.2 ± 1.5, and ∼0.8 M -1

  2. Concentration of ions Co(II), Ni(II) at the Tokem-250 carboxylic cation exchange for catalysts development

    Science.gov (United States)

    Zharkova, Valentina; Bobkova, Ludmila; Brichkov, Anton; Kozik, Vladimir

    2017-11-01

    Sorption and catalytic properties of the cation exchanger are investigated. It was found that the Tokem-250 has a wide operating range of pH. The value of the effective ionization constant of the functional groups of the cation exchanger (pKa) is 6.59. The Tokem-250 cation exchanger exhibits selectivity to Ni2+ ions to Co2+ (D˜103). This is probably due to the stability of ion-exchange complexes detected by the method of diffuse reflectance electron spectroscopy (ESDD). According to these data, for Co2+ ions, in contrast to Ni2+, tetragonal distortion of octahedral coordination is characteristic, which has a positive effect on the stability of complexes with Co2+. To obtain spherical catalysts on the basis of Tokem-250, cobalt-containing samples of cation exchanger were used. The developed spherical materials have catalytic activity in the reactions of deep and partial oxidation of n-heptane.

  3. DFT investigation of Ni(II) adsorption onto MA-DTPA/PVDF chelating membrane in the presence of coexistent cations and organic acids.

    Science.gov (United States)

    Song, Laizhou; Zhao, Xiaodan; Fu, Jie; Wang, Xiuli; Sheng, Yiping; Liu, Xiaowei

    2012-01-15

    Melamine-diethylenetriaminepentaacetic acid/polyvinylidene fluoride (MA-DTPA/PVDF) chelating membrane bearing polyaminecarboxylate groups was used to remove Ni(II) from nickel plating effluents. Adsorption experiments were conducted to study the adsorption of the membrane towards Ni(II) in Ni(II)-Ca(II), Ni(II)-NH(4)(+), Ni(II)-Fe(III) binary systems, and Ni(II)-lactic acid, Ni(II)-succinic acid and Ni(II)-citric acid complex systems. For the ternary nickel plating processes, the effects of 3d transition metals including Fe(II), Co(II), Cu(II) and Zn(II) on Ni(II) adsorption were evaluated. The influences of the aforementioned coexistent cations and organic acids were elucidated by the continuum solvation model (COSMO)-corrected density functional theory (DFT) method. Geometries and complexation energies were analyzed for metal-MA-DTPA and Ni(II)-organic acid complexes. DFT results accord with the experimental data, indicating that DFT is helpful to evaluate the complexation between the membrane and metal cations. The coexistent Ca(II) tends to form more stable complex with MA-DTPA ligand than NH(4)(+) and Fe(III), and can interfere with the formation of Ni(II)-MA-DTPA complex. The complexing sequence of 3d metals with MA-DTPA ligand is Zn(II)Ni(II)Ni(II). The stabilities of Ni(II)-organic acid complexes follow the order of lactic acidNi(II)-MA-DTPA complex. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Cation exchange removal of Cd from aqueous solution by NiO

    International Nuclear Information System (INIS)

    Mahmood, T.; Saddique, M.T.; Naeem, A.; Mustafa, S.; Dilara, B.; Raza, Z.A.

    2011-01-01

    Graphical abstract: Sorption of Cd on NiO particles is described by modified Langmuir adsorption isotherms. - Abstract: Detailed adsorption experiments of Cd from aqueous solution on NiO were conducted under batch process with different concentrations of Cd, time and temperature of the suspension. The solution pH is found to play a decisive role in the metal ions precipitation, surface dissolution and adsorption of metal ions onto the NiO. Preliminary adsorption experiments show that the selectivity of NiO towards different divalent metal ions follows the trend Pb > Zn > Co > Cd, which is related to their first hydrolysis equilibrium constant. The exchange between the proton from the NiO surface and the metal from solution is responsible for the adsorption. The cation/exchange mechanism essentially remains the same for Pb, Zn, Co and Cd ions. The sorption of Cd on NiO particles is described by the modified Langmuir adsorption isotherms. The isosteric heat of adsorption (ΔH) indicates the endothermic nature of the cation exchange process. Spectroscopic analyses provide evidence that Cd is chemisorbed onto the surface of NiO.

  5. Synthetic Control of Kinetic Reaction Pathway and Cationic Ordering in High-Ni Layered Oxide Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dawei [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory Physical Chemistry Solid Surfaces, Department of Chemistry, Xiamen University, Xiamen Fujian 361005 China; Kou, Ronghui [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Ren, Yang [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Sun, Cheng-Jun [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Zhao, Hu [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; Zhang, Ming-Jian [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen Guangdong 518055 P. R. China; Li, Yan [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Huq, Ashifia [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Ko, J. Y. Peter [The Cornell High Energy Synchrotron Source, Cornell University, Ithaca NY 14853 USA; Pan, Feng [School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen Guangdong 518055 P. R. China; Sun, Yang-Kook [Department of Energy Engineering, Hanyang University, Seoul 133-791 South Korea; Yang, Yong [Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory Physical Chemistry Solid Surfaces, Department of Chemistry, Xiamen University, Xiamen Fujian 361005 China; Amine, Khalil [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Bai, Jianming [National Synchrotron Light Source II, Brookhaven National Laboratory, Upton NY 11973 USA; Chen, Zonghai [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Wang, Feng [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA

    2017-08-25

    Nickel-rich layered transition metal oxides, LiNi1-x(MnCo)(x)O-2 (1-x >= 0.5), are appealing candidates for cathodes in next-generation lithium-ion batteries (LIBs) for electric vehicles and other large-scale applications, due to their high capacity and low cost. However, synthetic control of the structural ordering in such a complex quaternary system has been a great challenge, especially in the presence of high Ni content. Herein, synthesis reactions for preparing layered LiNi0.7Mn0.15Co0.15O2 (NMC71515) by solid-state methods are investigated through a combination of time-resolved in situ high-energy X-ray diffraction and absorption spectroscopy measurements. The real-time observation reveals a strong temperature dependence of the kinetics of cationic ordering in NMC71515 as a result of thermal-driven oxidation of transition metals and lithium/oxygen loss that concomitantly occur during heat treatment. Through synthetic control of the kinetic reaction pathway, a layered NMC71515 with low cationic disordering and a high reversible capacity is prepared in air. The findings may help to pave the way for designing high-Ni layered oxide cathodes for LIBs.

  6. Cation-Cation Complexes of Pentavalent Uranyl: From Disproportionation Intermediates to Stable Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Mougel, Victor; Horeglad, Pawel; Nocton, Gregory; Pecaut, Jacques; Mazzanti, Marinella [CEA, INAC, SCIB, Laboratoire de Reconnaissance Ionique et Chimie de Coordination, CEA-Grenoble, 38054 GRENOBLE, Cedex 09 (France)

    2010-07-01

    Three new cation cation complexes of pentavalent uranyl, stable with respect to the disproportionation reaction, have been prepared from the reaction of the precursor [(UO{sub 2}py{sub 5})-(KI{sub 2}py{sub 2})]{sub n} (1) with the Schiff base ligands salen{sup 2-}, acacen{sup 2-}, and salophen{sup 2-} (H{sub 2}salen N, N'-ethylene-bis(salicylidene-imine), H{sub 2}acacen=-N, N'-ethylenebis(acetylacetone-imine), H{sub 2}salophen=N, N'-phenylene-bis(salicylidene-imine)). The preparation of stable complexes requires a careful choice of counter ions and reaction conditions. Notably the reaction of 1 with salophen{sup 2-} in pyridine leads to immediate disproportionation, but in the presence of [18]crown-6 ([18]C-6) a stable complex forms. The solid-state structure of the four tetra-nuclear complexes ([UO{sub 2}-(acacen)]{sub 4}[{mu}{sub 8}-]{sub 2}[K([18]C-6)(py)]{sub 2}) (3) and ([UO{sub 2}(acacen)](4)[{mu}{sub 8}-]).2[K([222])(py)] (4) ([UO{sub 2}(salophen)](4)[{mu}{sub 8}-K]{sub 2}[mu(5)-KI]{sub 2}[(K([18]C-6)]).2 [K([18]C-6)-(thf){sub 2}].2I (5), and ([UO{sub 2}(salen)(4)][{mu}{sub 8}-Rb]{sub 2}[Rb([18]C-6)]{sub 2}) (9) ([222] = [222]cryptand, py =pyridine), presenting a T-shaped cation cation interaction has been determined by X-ray crystallographic studies. NMR spectroscopic and UV/Vis studies show that the tetra-nuclear structure is maintained in pyridine solution for the salen and acacen complexes. Stable mononuclear complexes of pentavalent uranyl are also obtained by reduction of the hexavalent uranyl Schiff base complexes with cobaltocene in pyridine in the absence of coordinating cations. The reactivity of the complex [U{sup V}O{sub 2}(salen)(py)][Cp*{sub 2}Co] with different alkali ions demonstrates the crucial effect of coordinating cations on the stability of cation cation complexes. The nature of the cation plays a key role in the preparation of stable cation cation complexes. Stable tetra-nuclear complexes form in the presence of K

  7. Raman spectroscopy of DNA-metal complexes. I. Interactions and conformational effects of the divalent cations: Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Pd, and Cd

    OpenAIRE

    Duguid, J.; Bloomfield, V.A.; Benevides, J.; Thomas Jr, G.J.

    1993-01-01

    Interactions of divalent metal cations (Mg2+, Ca2+, Ba2+, Sr2+, Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) with DNA have been investigated by laser Raman spectroscopy. Both genomic calf-thymus DNA (> 23 kilobase pairs) and mononucleosomal fragments (160 base pairs) were employed as targets of metal interaction in solutions containing 5 weight-% DNA and metal:phosphate molar ratios of 0.6:1. Raman difference spectra reveal that transition metal cations (Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) ind...

  8. Investigations on complexing cation exchangers and their use for trace analysis in natural waters

    International Nuclear Information System (INIS)

    Lang, H.

    1991-12-01

    The practicability of cation preconcentrations from natural waters by use of EDTrA- and 5-s-oxine- celluloses has been studied. For that purpose the protonation constants as well as the complexation capacities were determined by use of acid/base titrations. In additional titration experiments the complex stability constants for Cu 2+ , Mn 2+ , Co 2+ , Ni 2+ and Ca 2+ were determined examplarely. The interpretation of the experiments was performed using an optimised fit between calculated and experimentally determined pH-titration curves. Calculations have been done by the computer code 'MINEQL'. The determined stability constants are in the same order of magnitude as those given in literature for the water soluble complexes of EDTA, NTA or 5-s-oxine. The preconcentration of cations from natural water samples occurs in accordance with the theoretical predictions. Not ignorable disturbances appear for cations forming hydroxides or oxides in neutral or weakly acidic solutions. By use of radioactive isotopes for Sn 2+ , Zn 4+ and Nb 5+ it can be shown that those ions may form particles or colloids in natural waters. These particles will be filtered in the columns packed with the celluloses and can hardly be removed from there. (author)

  9. Strongly reduced band gap in NiMn2O4 due to cation exchange

    International Nuclear Information System (INIS)

    Huang, Jhih-Rong; Hsu, Han; Cheng, Ching

    2014-01-01

    NiMn 2 O 4 is extensively used as a basis material for temperature sensors due to its negative temperature coefficient of resistance (NTCR), which is commonly attributed to the hopping mechanism involving coexisting octahedral-site Mn 4+ and Mn 3+ . Using density-functional theory + Hubbard U calculations, we identify a ferrimagnetic inverse spinel phase as the collinear ground state of NiMn 2 O 4 . By a 12.5% cation exchange, a mixed phase with slightly higher energy can be constructed, accompanied by the formation of an impurity-like band in the original 1 eV band gap. This impurity-like band reduces the gap to 0.35 eV, suggesting a possible source of NTCR. - Highlights: • Density functional based calculations were used to study collinear phase of NiMn 2 O 4 . • The ground-state structure is a ferrimagnetic inverse spinel phase. • The tetrahedral and octahedral Mn cations have ferromagnetic interactions. • A 12.5% cation exchange introduces an impurity-like band in the original 1 eV gap. • The 0.35 eV gap suggests a source of negative temperature coefficient of resistance

  10. Computational studies of a paramagnetic planar dibenzotetraaza[14]annulene Ni(II) complex.

    Science.gov (United States)

    Rabaâ, Hassan; Khaledi, Hamid; Olmstead, Marilyn M; Sundholm, Dage

    2015-05-28

    A square-planar Ni(II) dibenzotetraaza[14]annulene complex substituted with two 3,3-dimethylindolenine groups in the meso positions has recently been synthesized and characterized experimentally. In the solid-state, the Ni(II) complex forms linear π-interacting stacks with Ni···Ni separations of 3.448(2) Å. Measurements of the temperature dependence of the magnetic susceptibility revealed a drastic change in the magnetic properties at a temperature of 13 K, indicating a transition from low-to-high spin states. The molecular structures of the free-base ligand, the lowest singlet, and triplet states of the monomer and the dimer of the Ni complex have been studied computationally using density functional theory (DFT) and ab initio correlation levels of theory. In calculations at the second-order Møller-Plesset (MP2) perturbation theory level, a large energy of 260 kcal mol(-1) was obtained for the singlet-triplet splitting, suggesting that an alternative explanation of the observed magnetic properties is needed. The large energy splitting between the singlet and triplet states suggests that the observed change in the magnetism at very low temperatures is due to spin-orbit coupling effects originating from weak interactions between the fine-structure states of the Ni cations in the complex. The lowest electronic excitation energies of the dibenzotetraaza[14]annulene Ni(II) complex calculated at the time-dependent density functional theory (TDDFT) levels are in good agreement with values deduced from the experimental UV-vis spectrum. Calculations at the second-order algebraic-diagrammatic construction (ADC(2)) level on the dimer of the meso-substituted 3,3-dimethylindolenine dibenzotetraaza[14] annulene Ni(II) complex yielded Stokes shifts of 85-100 nm for the lowest excited singlet states. Calculations of the strength of the magnetically induced ring current for the free-base 3,3-dimethylindolenine-substituted dibenzotetraaza[14]annulene show that the annulene

  11. A theoretical study of complexes formed between cations and curved aromatic systems: electrostatics does not always control cation-π interaction.

    Science.gov (United States)

    Carrazana-García, Jorge A; Cabaleiro-Lago, Enrique M; Rodríguez-Otero, Jesús

    2017-04-19

    The present work studies the interaction of two extended curved π-systems (corannulene and sumanene) with various cations (sodium, potassium, ammonium, tetramethylammonium, guanidinium and imidazolium). Polyatomic cations are models of groups found in important biomolecules in which cation-π interaction plays a fundamental role. The results indicate an important size effect: with extended π systems and cations of the size of potassium and larger, dispersion is much more important than has been generally recognized for cation-π interactions. In most of the systems studied here, the stability of the cationcomplexes is the result of a balanced combination of electrostatic, induction and dispersion contributions. None of the systems studied here owes its stability to the electrostatic interaction more than 42%. Induction dominates stabilization in complexes with sodium, and in some of the potassium and ammonium complexes. In complexes with large cations and with flat cations dispersion is the major stabilizing contribution and can provide more than 50% of the stabilization energy. This implies that theoretical studies of the cation-π interaction involving large or even medium-size fragments require a level of calculation capable of properly modelling dispersion. The separation between the cation and the π system is another important factor to take into account, especially when the fragments of the cationcomplex are bound (for example, to a protein backbone) and cannot interact at the most favourable distance.

  12. Aromatic Amino Acids-Guanidinium Complexes through Cation-π Interactions

    Directory of Open Access Journals (Sweden)

    Cristina Trujillo

    2015-05-01

    Full Text Available Continuing with our interest in the guanidinium group and the different interactions than can establish, we have carried out a theoretical study of the complexes formed by this cation and the aromatic amino acids (phenylalanine, histidine, tryptophan and tyrosine using DFT methods and PCM-water solvation. Both hydrogen bonds and cation-π interactions have been found upon complexation. These interactions have been characterized by means of the analysis of the molecular electron density using the Atoms-in-Molecules approach as well as the orbital interactions using the Natural Bond Orbital methodology. Finally, the effect that the cation-π and hydrogen bond interactions exert on the aromaticity of the corresponding amino acids has been evaluated by calculating the theoretical NICS values, finding that the aromatic character was not heavily modified upon complexation.

  13. Mass spectral analysis of cationic and neutral technetium complexes

    International Nuclear Information System (INIS)

    Unger, S.E.; McCormick, T.J.; Nunn, A.N.; Treher, E.N.

    1986-01-01

    Cationic and neutral technetium compounds have been characterized by mass spectrometry using a variety of ionization methods. These compounds include octahedral cationic complexes containing phosphorous and arsenic ligands such as DIPHOS and DIARS and neutral complexes containing PnAO and dimethylglyoxime, DMG, or cyclohexanedione dioxime, CDO, ligands. Boronate esters incorporating methyl and butyl derivatives of the DMG and CDO dioximes represent a new class of seven-coordinate Tc radiopharmaceuticals whose characterization by mass spectrometry has not previously been described. These complexes show promise as myocardial imaging agents. (author)

  14. IRMPD Action Spectroscopy of Alkali Metal Cation-Cytosine Complexes: Effects of Alkali Metal Cation Size on Gas Phase Conformation

    NARCIS (Netherlands)

    Yang, B.; Wu, R.R.; Polfer, N.C.; Berden, G.; Oomens, J.; Rodgers, M.T.

    2013-01-01

    The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra of five alkali metal cation-cytosine complexes exhibit both

  15. Electronic structure of Ni-- and Ni2--ethylene cluster complexes

    International Nuclear Information System (INIS)

    Basch, H.; Newton, M.D.; Moskowitz, J.W.

    1978-01-01

    The electronic structure of metal cluster--ethylene complexes has been investigated by carrying out ab initio bonding pair-correlated, self-consistent field, and configuration interaction (CI) calculations on the NiC 2 H 4 and Ni 2 C 2 H 4 species. The π-NiC 2 H 4 and π-Ni 2 C 2 H 4 cluster complexes are found to be bound, the former only with CI, while disigma-Ni 2 C 2 H 4 has only a repulsive Ni 2 --C 2 H 4 ground state potential curve. The bonding in the π-type cluster complexes can be described as follows: The metal atom configuration is 3d 9 4s 1 with the 4s hybridized (by the metal 4p) away from the ethylene molecule, thereby allowing the π orbital to form a dative sigma bond with the metal atom. The bonding interaction is promoted by the presence of a second nickel atom behind the first one, leading to a 4s orbital electron deficiency of the bonded nickel atom and thus making this nickel atom a better electron acceptor. Back donation from the occupied metal 3d into the ethylene π* molecular orbital also takes place to some extent, and thus both features of the classical Dewar--Chatt--Duncanson model are observed. The π-Ni 2 C 2 H 4 species is analyzed in terms of the addition of a bare nickel atom to a π-NiC 2 H 4 cluster complex, with concomitant stabilization of the orbitals of the bonded nickel atom. A study of the excited electronic states of π-NiC 2 H 4 shows that low-lying 4s→π* and 3d→π* (M→L) charge transfer transitions are predicted. The former is not observed experimentally, probably due to the diffuse nature of the 4s orbital. The relationship between small cluster--ethylene complex systems and ethylene chemisorption on a nickel metal surface is discussed

  16. Complexes in the Ni2+-imidazole-RN(CH2COO-)2 systems. The crystal structures of tris(imidazole)iminodiacetatonickel(II) monohydrate, hexa(imidazole)nickel(II) bis(N-methyliminodiacetato)nickelate(II) hexahydrate, and tetra(aqua)bis(imidazole)nickel(II) bis(N-benzyliminodiacetato)nickelate(II)

    International Nuclear Information System (INIS)

    Polyakova, I.N.; Sergienko, V.S.; Poznyak, A.L.

    2000-01-01

    Crystals of different compositions, namely, [Ni(Ida)(Im) 3 ] · H 2 O (I), [Ni(Im) 6 ][Ni(Mida) 2 ] · 6H 2 O (II), and [Ni(Im) 2 (H 2 O) 4 ][Ni(Bida) 2 ] (III), have been precipitated from aqueous solutions of the Ni 2+ -Lig 2- Im systems, where Lig 2- is Ida, Mida, and Bida, respectively. The crystal structures of I-III are determined by X-ray diffraction analysis (R = 0.0307, 0.0348, and 0.0302 for 3061, 4706, and 2882 reflections, respectively). Crystals I are built of monomeric mixed-ligand complexes and molecules of crystallization water, which are interlinked by hydrogen bonds into a three-dimensional framework. In II and III, the ligands Lig 2- and Im form charged complexes separately. In II, the cationic and anionic layers of the complexes alternate along the c-axis. Numerous hydrogen bonds involving molecules of crystallization water link the layers into a three-dimensional framework. In III, the cationic and anionic complexes, which serve as proton donors and acceptors, respectively, are bound into layers parallel to the xy plane

  17. On the nature of Ni···Ni interaction in a model dimeric Ni complex.

    Science.gov (United States)

    Kamiński, Radosław; Herbaczyńska, Beata; Srebro, Monika; Pietrzykowski, Antoni; Michalak, Artur; Jerzykiewicz, Lucjan B; Woźniak, Krzysztof

    2011-06-07

    A new dinuclear complex (NiC(5)H(4)SiMe(2)CHCH(2))(2) (2) was prepared by reacting nickelocene derivative [(C(5)H(4)SiMe(2)CH=CH(2))(2)Ni] (1) with methyllithium (MeLi). Good quality crystals were subjected to a high-resolution X-ray measurement. Subsequent multipole refinement yielded accurate description of electron density distribution. Detailed inspection of experimental electron density in Ni···Ni contact revealed that the nickel atoms are bonded and significant deformation of the metal valence shell is related to different populations of the d-orbitals. The existence of the Ni···Ni bond path explains the lack of unpaired electrons in the complex due to a possible exchange channel.

  18. Cation distribution in CuFe{sub 2}O{sub 4} nanoparticles: Effects of Ni doping on magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Thanh, Nguyen Kim; Loan, To Thanh, E-mail: totloan@itims.edu.vn; Anh, Luong Ngoc; Duong, Nguyen Phuc; Hien, Than Duc [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, Hanoi 100000 (Viet Nam); Soontaranon, Siriwat; Thammajak, Nirawat [Synchrotron Light Research Institute, 111 University Avenue, Suranaree, Muang, Nakhon Ratchasima 30000 (Thailand)

    2016-10-14

    The Cu{sub 1−x}Ni{sub x}Fe{sub 2}O{sub 4} nanoparticles (with x = 0, 0.3, 0.5, 0.7, and 1) were synthesized by using spray co-precipitation method at annealing temperature T{sub a} = 900 °C in air for 5 h. The crystal structure, microstructure, oxidation state, and magnetic properties of the samples were characterized by using X-ray diffraction, synchrotron X-ray diffraction, scanning electron microscopy, X-ray absorption spectroscopy, and vibrating sample magnetometer. It was shown that all the samples have cubic structure. Lattice constant and grain size decrease, while the Curie temperature T{sub C} increases with increasing of Ni{sup 2+} content. A small amount of Fe{sup 2+} was found in all the samples. Cation distribution was determined by using a combination of magnetization measurements, extended X-ray absorption fine structure analysis, and Rietveld refinement from synchrotron X-ray diffraction data. It was indicated that Ni{sup 2+} ions occupy in octahedral site only, while Cu{sup 2+} ions distribute in both tetrahedral and octahedral sites. The variation of magnetic parameters is discussed based on Ni{sup 2+} concentration, grain size, the cation distribution, surface effect, and the presence of Fe{sup 2+} ion in the samples.

  19. Cobalt(2) and nickel(2) tris-acetylacetonates with alkali metal cations in outer sphere

    International Nuclear Information System (INIS)

    Steblyanko, A.Yu.; Grigor'ev, A.N.; Martynenko, L.I.

    1996-01-01

    Anhydrous tris-acetylacetonates of Co(2) and Ni(2) with alkali metal cations in outer sphere were synthesized and investigated by different physicochemical methods. Chemical analysis and IR-spectroscopy show, that complex composition corresponds to the formula Eh[MA 3 ] (where Eh + - Li + , Na + , K + , Rb + , Cs + ; M - Co(2), Ni(2); A - - acetyacetonate-ion). Eh[MA 3 ] heating in vacuum leads to transition of volatile Co(2) and Ni(2) acetylacetonates to gaseous phase. The data of photoelectron spectroscopy and vacuum sublimation show, that Li[MA 3 ] is transformed to gaseous phase congruently and only partially dissociates to EhA and MA 2 . Li[MA 3 ] and Cs[MA 3 ] are characterized by the lowest thermal stability at atmospheric pressure. Low stability of Li[MA 3 ] is related with detachment of one of A - radical from [MA 3 ] complex anion by Li + cation under conditions, when LiA and Li[MA 3 ] are volatile. 11 refs.; 2 figs.; 3 tabs

  20. Complexes of natural carbohydrates with metal cations

    International Nuclear Information System (INIS)

    Alekseev, Yurii E; Garnovskii, Alexander D; Zhdanov, Yu A

    1998-01-01

    Data on the interaction of natural carbohydrates (mono-, oligo-, and poly-saccharides, amino sugars, and natural organic acids of carbohydrate origin) with metal cations are surveyed and described systematically. The structural diversity of carbohydrate metal complexes, caused by some specific features of carbohydrates as ligands, is demonstrated. The influence of complex formation on the chemical properties of carbohydrates is discussed. It is shown that the formation of metal complexes plays an important role in the configurational and conformational analysis of carbohydrates. The practical significance of the coordination interaction in the series of carbohydrate ligands is demonstrated. The bibliography includes 571 references.

  1. Solvation Effect on Complexation of Alkali Metal Cations by a Calix[4]arene Ketone Derivative.

    Science.gov (United States)

    Požar, Josip; Nikšić-Franjić, Ivana; Cvetnić, Marija; Leko, Katarina; Cindro, Nikola; Pičuljan, Katarina; Borilović, Ivana; Frkanec, Leo; Tomišić, Vladislav

    2017-09-14

    The medium effect on the complexation of alkali metal cations with a calix[4]arene ketone derivative (L) was systematically examined in methanol, ethanol, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile. In all solvents the binding of Na + cation by L was rather efficient, whereas the complexation of other alkali metal cations was observed only in methanol and acetonitrile. Complexation reactions were enthalpically controlled, while ligand dissolution was endothermic in all cases. A notable influence of the solvent on NaL + complex stability could be mainly attributed to the differences in complexation entropies. The higher NaL + stability in comparison to complexes with other alkali metal cations in acetonitrile was predominantly due to a more favorable complexation enthalpy. The 1 H NMR investigations revealed a relatively low affinity of the calixarene sodium complex for inclusion of the solvent molecule in the calixarene hydrophobic cavity, with the exception of acetonitrile. Differences in complex stabilities in the explored solvents, apart from N,N-dimethylformamide and acetonitrile, could be mostly explained by taking into account solely the cation and complex solvation. A considerable solvent effect on the complexation equilibria was proven to be due to an interesting interplay between the transfer enthalpies and entropies of the reactants and the complexes formed.

  2. Synthesis and SMM behaviour of trinuclear versus dinuclear 3d-5f uranyl(v)-cobalt(ii) cation-cation complexes.

    Science.gov (United States)

    Chatelain, Lucile; Tuna, Floriana; Pécaut, Jacques; Mazzanti, Marinella

    2017-05-02

    Trinuclear versus dinuclear heterodimetallic U V O 2 + Co 2+ complexes were selectively assembled via a cation-cation interaction by tuning the ligand. The trimeric complex 2, with a linear [Co-O[double bond, length as m-dash]U[double bond, length as m-dash]O-Co] core, exhibits magnetic exchange and slow relaxation with a reversal barrier of 30.5 ± 0.9 K providing the first example of a U-Co exchange-coupled SMM.

  3. A quantitative mechanistic description of Ni, Zn and Ca sorption on Na-montmorillonite. Part III: modelling

    International Nuclear Information System (INIS)

    Baeyens, B.; Bradbury, M.H.

    1995-07-01

    Titration and sorption measurements, carried out under a wide variety of conditions on Na-montmorillonite, were examined in terms of cation exchange and surface complexation mechanisms. A computer code called MINSORB was developed and used throughout this work. This code allowed the uptake of radionuclides by both mechanisms to be calculated simultaneously; also taking into account competitive reactions from other cations present. A stepwise iterative fitting/modelling procedure is described. For the case of Na-montmorillonite it is demonstrated that an electrostatic term in the surface complexation model is not required. A basic data set comprising of site capacities and protonation/deprotonation constants was defined, which was valid for all surface complexation sorption reactions. The main study was carried out with Ni, but impurity cations present in the system, particularly Zn, had to be examined in addition due to their competitive effects on Ni sorption. The surface complexation behaviour of Ni and Zn was investigated in detail to give intrinsic surface complexation constants on two of the =SOH type sites included in the model. The sorption of Mg, Ca and Mn is also considered, though in less detail, and estimated surface complexation constants for these nuclides are presented. Cation exchange was included in all of the calculations. Measured selectivity coefficients for Ni-Na, Zn-Na and Ca-Na exchange reactions are given. The model, with the derived parameters, allowed all the data from titration measurements through sorption edges to sorption isotherms to be calculated. (author) 31 figs., 9 tabs., refs

  4. A quantitative mechanistic description of Ni, Zn and Ca sorption on Na-Montmorillonite. Part III: Modelling

    International Nuclear Information System (INIS)

    Baeyens, B.; Bradbury, M.H.

    1995-07-01

    Titration and sorption measurements, carried out under a wide variety of conditions on Na-montmorillonite, were examined in terms of cation exchange and surface complexation mechanisms. A computer code called MINSORB was developed and used throughout this work. This code allowed the uptake of radionuclides by both mechanisms to be calculated simultaneously; also taking into account competitive reactions from other cations present. A stepwise iterative fitting/modelling procedure is described. For the case of Na-montmorillonite it is demonstrated that an electrostatic term in the surface complexation model is not required. A basic data set comprising of site capacities and protonation/deprotonation constants was defined, which was valid for all surface complexation sorption reactions. The main study was carried out with Ni, but impurity cations present in the system, particularly Zn, had to be examined in addition due to their competitive effects on Ni sorption. The surface complexation behaviour of Ni and Zn was investigated in detail to give intrinsic surface complexation constants on two of the ≡SOH type sites included in the model. The sorption of Mg, Ca and Mn is also considered, though in less detail, and estimated surface complexation constants for these nuclides are presented. Cation exchange was included in all of the calculations. Measured selectivity coefficients for Ni-Na, Zn-Na and Ca-Na exchange reactions are given. The model, with the derived parameters, allowed all the data from titration measurements through sorption edges to sorption isotherms to be calculated. (author) 31 figs., 9 tabs., refs

  5. Preparation of fine Ni powders from nickel hydrazine complex

    International Nuclear Information System (INIS)

    Park, Jung Woo; Chae, Eun H.; Kim, Sang H.; Lee, Jong Ho; Kim, Jeong Wook; Yoon, Seon Mi; Choi, Jae-Young

    2006-01-01

    Fine nickel powders with narrow size distribution have been prepared from the reduction of nickel hydrazine complexes in aqueous solution. The pure nickel hydrazine complexes, [Ni(N 2 H 4 ) 3 ]Cl 2 were prepared with the molar ratio of N 2 H 4 /Ni 2+ = 4.5, while a mixture of complexes, such as Ni(N 2 H 4 ) 2 Cl 2 , [Ni(N 2 H 4 ) 3 ]Cl 2 , and [Ni(NH 3 ) 6 ]Cl 2 were formed with N 2 H 4 /Ni 2+ 2+ to metallic Ni powder proceeded via the formation of nickel hydroxide which was reduced by hydrazine liberated from the ligand exchange reaction between the nickel hydrazine complex and NaOH. The standard deviation of the particle size decreased with the decreasing molar concentration of nickel hydrazine complex while the mean particle size increased. As the amount of hydrazine increased, the surface roughness of the particles was improved significantly due to the catalytic decomposition of the excess hydrazine at the surface of the nickel particle. It was found that average particle size could be controlled from 150 to 380 nm by adjusting the reaction molar ratio and temperature

  6. Selective transport of metal ions through cation exchange membrane in the presence of a complexing agent

    Energy Technology Data Exchange (ETDEWEB)

    Tingchia Huang; Jaukai Wang (National Cheng Kung Univ., Tainan (Taiwan, Province of China))

    1993-01-01

    Selective transport of metal ions through a cation exchange membrane was studied in stirred batch dialyzer for the systems Ni[sup 2+]-Cu[sup 2+] and Cu[sup 2+]-Fe[sup 3+]. Oxalic acid, malonic acid, citric acid, glycine, and ethylenediaminetetraacetic acid were employed as the complexing agents added in the feed solution in order to increase the permselectivity of metal ions. The experimental results show that the selective transport behavior of metal ions depends on the valence and the concentration of metal ions, the stoichiometric ratio of complexing agent to metal ions, and the pH value of the feed solution, but is independent of the concentration of counterion in the stripping phase. A theoretical approach was formulated on the basis of the Nernst-Planck equation and interface quasi-equilibrium. Theoretical solutions obtained from numerical calculation were in agreement with the experimental data.

  7. Removal of Cr(VI) and Ni(II) from aqueous solution by fused yeast: Study of cations release and biosorption mechanism

    International Nuclear Information System (INIS)

    Yin Hua; He Baoyan; Peng Hui; Ye Jinshao; Yang Feng; Zhang Na

    2008-01-01

    Biosorption of Cr(VI) and Ni(II) by a fused yeast from Candida tropicalis and Candida lipolytica under varying range of pH, initial metal concentration and reaction time was investigated. Net cation release and Cr removal reached 2.000 mmol/l and 81.37% when treating 20 mg/l Cr(VI) at pH 2 with 25 mg/l biomass for 30 min, while for Ni were 0.351 mmol/l and 64.60%, respectively. Trace metal elements such as Co, Cu, Mn, Mo, Se and Zn played active role in biosorption as important ingredients of functional enzymes. Cr(VI) was reduced to less toxic Cr(III) and chelated with extracellular secretions, and further accumulated inside the cells. For Ni biosorption, however, largely a passive uptake process influenced by ion gradient led to lower adsorption capacity and cations release. Fourier transform infrared (FTIR) spectrum analysis indicated that amide and pyridine on cells were involved in binding with Cr, but for Ni, bound-OH and nitro-compounds were the main related functional groups. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis confirmed that considerable amounts of metals precipitated on cell surface when dealing with high concentration metals

  8. Complex Macromolecular Architectures by Living Cationic Polymerization

    KAUST Repository

    Alghamdi, Reem D.

    2015-05-01

    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  9. Influence of cations and anions on the formation of β-FeOOH

    International Nuclear Information System (INIS)

    Kamimura, T.; Nasu, S.; Segi, T.; Tazaki, T.; Miyuki, H.; Morimoto, S.; Kudo, T.

    2005-01-01

    In the presence of cations such as Cr 3+ , Cu 2+ and Ni 2+ , and anions such as SO 4 2- and NO 3 - , precipitation of β-FeOOH from Fe 3+ -solution containing Cl - by hydrolysis have been investigated by means of X-ray diffraction technique (XRD), Mossbauer spectroscopy (MS) and transmission electron microscopy (TEM). XRD peaks of β-FeOOH were broadened when the cations were added as sulfates, and this tendency for Cr 3+ was significantly observed. When the cations were added as nitrates, there was no significant change in XRD peaks. Inductively coupled plasma (ICP) analysis showed that only Cr added as sulfate was contained in β-FeOOH. Ni and Cu added as sulfates, and any cations added as nitrates were not contained in it. When β-FeOOH was synthesized with Na 2 SO 4 , the XRD peaks were broadened. XRD-peak broadening was mainly caused by the coexistence of SO 4 2- ion. The incorporation of cations in β-FeOOH is affected by coexistent anions, and the XRD-peak broadening is caused by not only cations but also anions. This behavior has been discussed in association with the stability of Fe 3+ -complexes in the solution

  10. From cation to oxide: hydroxylation and condensation of aqueous complexes

    International Nuclear Information System (INIS)

    Jolivet, J.P.

    1997-01-01

    Hydroxylation, condensation and precipitation of metal cations in aqueous solution are briefly reviewed. Hydroxylation of aqueous complexes essentially depends on the format charge (oxidation state), the size and the pH of the medium. It is the step allowing the condensation reaction. Depending on the nature of complexes (aqua-hydroxo, oxo-hydroxo), the. mechanism of condensation is different, olation or ox-olation respectively. The first one leads to poly-cations or hydroxides more or less stable against dehydration. The second one leads to poly-anions or oxides. Oligomeric species (poly-cations, poly-anions) are form from charged monomer complexes while the formation of solid phases requires non-charged precursors. Because of their high lability, charged oligomers are never the precursors of solids phases. The main routes for the formation of solid phases from solution are studied with two important and representative elements, Al and Si. For Al 3+ ions, different methods (base addition in solution, thermo-hydrolysis, hydrothermal synthesis) are discussed in relation to the crystal structure of the solid phase obtained. For silicic species condensing by ox-olation, the role of acid or base catalysis on the morphology of gels is studied. The influence of complexing ligands on the processes and on the characteristics of solids (morphology of particles, basic salts and polymetallic oxides formation) is studied. (author)

  11. Cation distribution in Ni-substituted Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles: A Raman, Mössbauer, X-ray diffraction and electron spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Thota, Suneetha [Microwave Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Kashyap, Subhash C., E-mail: skashyap@physics.iitd.ac.in [Microwave Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Sharma, Shiv K. [Hawaii Institute of Geophysics and Planetology, University of Hawaii (UH), Honolulu, HI 96822 (United States); Reddy, V.R. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452017 (India)

    2016-04-15

    Graphical abstract: - Highlights: • Synthesized Mn{sub 0.5−x}Ni{sub x}Zn{sub 0.5}Fe{sub 2}O{sub 4}, nanoparticles (0.05 ≤ x ≤ 0.45) at low temperature. • Raman studies established that Fe and Zn ions occupy A site in equal fraction. • {sup 57}Fe Mossbauer study revealed that Ni and Mn ions occupy nearly 25% of B sites. • Electron spectroscopy (XPS) confirmed that nearly 25% Fe{sup 3+} dwells at A sites. • Diffraction peak intensity (X-ray) quantified cations distribution at A- and B-sites. - Abstract: In this paper we report the structural, vibration, and electronic-structure parameters (bonding and valence of cations) of single phase cubic mixed spinel nanoparticles of (Zn{sub δ}Mn{sub γ}Fe{sub 1−(γ+δ)})[Ni{sub x}Zn{sub 0.5−δ}Mn{sub 0.5−γ−x}Fe{sub 1+(γ+δ)}]O{sub 4} where x = 0.05–0.45 with an aim to determine cation-distribution i.e. δ and γ in these samples. The Raman spectroscopy has established that only Fe and Zn cations occupy tetrahedral interstitial sites in a FCC anion lattice in nearly equal fraction, and Mössbauer spectra have shown that Fe{sup 3+} cations are present at both, tetrahedral and octahedral interstitial sites and Ni{sup 2+} cations are situated at the octahedral sites in all the substituted samples. The photoelectron spectra also revealed the presence of Fe{sup 3+} cations at both the interstitial sites. The best possible cationic distribution in Ni substituted Mn–Zn ferrites has been estimated by reiteratively calculating the intensity ratios of various pairs of X-ray diffraction peaks and matching with the observed intensity ratios.

  12. Cationic Tungsten(VI) Penta-Methyl Complex: Synthesis, Characterization and its Application in Olefin Metathesis Reaction

    KAUST Repository

    Dey, Raju; Samantaray, Manoja; Callens, Emmanuel; Hamieh, Ali Imad Ali; Emwas, Abdul-Hamid M.; Abou-Hamad, Edy; Kavitake, Santosh Giridhar; Basset, Jean-Marie

    2016-01-01

    Tungsten-hexa-methyl readily reacts with B(C6F5)3 in dichloromethane and generates the corresponding well-defined cationic tungsten-penta-methyl complex which was identified precisely by 1H NMR, 13C NMR, 1H-13C NMR correlation spectroscopy. Unlike WMe6, this cationic complex has low energy barrier to form tungsten carbene intermediate, which was further supported by the fact that WMe6 alone has no activity in olefin metathesis reaction whereas the cationic complex shows catalytic activity for self-metathesis of 1-octene.

  13. Cationic Tungsten(VI) Penta-Methyl Complex: Synthesis, Characterization and its Application in Olefin Metathesis Reaction

    KAUST Repository

    Dey, Raju

    2016-04-13

    Tungsten-hexa-methyl readily reacts with B(C6F5)3 in dichloromethane and generates the corresponding well-defined cationic tungsten-penta-methyl complex which was identified precisely by 1H NMR, 13C NMR, 1H-13C NMR correlation spectroscopy. Unlike WMe6, this cationic complex has low energy barrier to form tungsten carbene intermediate, which was further supported by the fact that WMe6 alone has no activity in olefin metathesis reaction whereas the cationic complex shows catalytic activity for self-metathesis of 1-octene.

  14. Synthesis and Crystal Structure of Binuclear and Pentanuclear Nickel(II Complexes Containing 4-(salicylaldiminatoantipyrine Schiff base

    Directory of Open Access Journals (Sweden)

    Mohamed N. EL-Kaheli

    2015-11-01

    Full Text Available The new title binuclear Ni (II compound  (1 and the novel pentanuclear Ni (II cluster {[   } (2 are formed from the reaction of an asymmetric Schiff base ligand L (L = 4-(salicylaldiminatoantipyrine with Ni .4  in the former or Ni(ClO42.6H2O in presence of malonate in the later.  Complex (1 consists of ( ]+ cation and one uncoordinated tetraphenylborate anion.  The cation adopts a distorted octahedral arrangement around each metal center.  In the binuclear unit both Ni(II ions are linked through two phenolate (µ2-O oxygen atoms of L, and two oxygen atoms of a  bridging carboxylate group. Each Ni (II coordinates to four oxygen atoms at the basal plane, two oxygen atoms from two bridging phenolate groups, one from pyrazolone ring and the last of an aqua molecule, and at the axial positions to a bridging carboxylate-O atom and an azomethine nitrogen atom.  In the pentanuclear cluster (2 consisting of [ ]+2 cation and two tetraphenylborate anions, the core of the cation is assembled by four [Ni( ] units, linked to the central Ni-ion by two bridging water molecules. The resulting coordination sphere for the external symmetry related nickel ions is a pseudo octahedron.  The central Ni-atom unusually adopts dodecahedron geometry through its coordination to eight bridging water molecules. In complex (1 each Ni-atom is coordinated to one tridentate L ligand and in complex (2 each [Ni ( ] unit is coordinated to two bidentate L ligands.  Inter-and intramolecular hydrogen bonds are present in both crystal structures.

  15. Neutral glycoconjugated amide-based calix[4]arenes: complexation of alkali metal cations in water.

    Science.gov (United States)

    Cindro, Nikola; Požar, Josip; Barišić, Dajana; Bregović, Nikola; Pičuljan, Katarina; Tomaš, Renato; Frkanec, Leo; Tomišić, Vladislav

    2018-02-07

    Cation complexation in water presents a unique challenge in calixarene chemistry, mostly due to the fact that a vast majority of calixarene-based cation receptors is not soluble in water or their solubility has been achieved by introducing functionalities capable of (de)protonation. Such an approach inevitably involves the presence of counterions which compete with target cations for the calixarene binding site, and also rather often requires the use of ion-containing buffer solutions in order to control the pH. Herein we devised a new strategy towards the solution of this problem, based on introducing carbohydrate units at the lower or upper rim of calix[4]arenes which comprise efficient cation binding sites. In this context, we prepared neutral, water-soluble receptors with secondary or tertiary amide coordinating groups, and studied their complexation with alkali metal cations in aqueous and methanol (for the comparison purpose) solutions. Complexation thermodynamics was quantitatively characterized by UV spectrometry and isothermal titration calorimetry, revealing that one of the prepared tertiary amide derivatives is capable of remarkably efficient (log K ≈ 5) and selective binding of sodium cations among alkali metal cations in water. Given the ease of the synthetic procedure used, and thus the variety of accessible analogues, this study can serve as a platform for the development of reagents for diverse purposes in aqueous media.

  16. The Noah's Ark experiment: species dependent biodistributions of cationic 99mTc complexes

    International Nuclear Information System (INIS)

    Deutsch, Edward; Ketring, A.R.; Libson, Karen; Vanderheyden, J.-L.; Hirth, W.W.

    1989-01-01

    The time dependent biodistributions of three related 99m Tc complexes of 1, 2-bis(dimethylphosphino)ethane (DMPE) were evaluated in several animal species including humans: trans-[ 99m Tc v (DMPE) 2 O 2 ] + , trans-[ 99m Tc III (DMPE) 2 Cl 2 ] + and [ 99m Tc I (DMPE) 3 ] + . Imaging studies were performed in 10 animal species to evaluate these complexes as myocardial perfusion imaging agents. Animal models adequately predict the uninteresting behaviour of the Tc(V) cation in humans, predict to only a very limited extent the behaviour of the Tc(III) cation in humans and totally fail to predict the behaviour of the Tc(I) cation in humans. (U.K.)

  17. Study of the alkaline cations complexation by photo-isomerizable calixarenes; Etude de la complexation de cations alcalins par des calixarenes photoisomerisables

    Energy Technology Data Exchange (ETDEWEB)

    Reynier, N.

    1996-04-25

    The first step to reduce the volume and the toxicity of radioactive waste coming from the spent fuel reprocessing is to separate long life radioisotopes from others ones with a shorter period. The aim of this study is to show that the control of the two phenomenons, complexation of the cation by the calixarenes and its de-complexation, can be envisaged by the introduction on the molecule of a chromophore group, azo benzene, able to modify the complexing site structure of the calixarenes with an isomerization trans-cis induced by ultraviolet radiation, and isomerization cis-trans thermally induced by a visible radiation. (N.C.). 112 refs., 78 figs., 23 tabs.

  18. Coordination phenomena of cationic uranium(iv) complexes

    International Nuclear Information System (INIS)

    Rohwer, H.E.

    1974-12-01

    The coordination properties of the cationic uranium(IV) complexes UCl 3 + , UCl 2 2+ , UCl 3+ , and U 4+ were studied in a non-aqueous medium in the presence of perchlorate as counterion which, however, proved to coordinate to a much greater extent than expected. The strong neutral ligand, HMPA, could successively displace some of the perchlorates. An electrostatic model for the U(CIO 4 ) 4 -HMPA-acetone system compared favourably with the actual results. This emphasized the high ionic content in the bonding with actenoid cations, even with such a high charge as +4 . These conclusions are in agreement with studies 75 in which nitrate acts as counter ion. Correspondingly the uranium (IV) chemistry is characterized by the absence of typical 3d-organometallic chemistry, for example, strong bonding with CO, P(Phi) 3 etc, which strongly depends on covalent bonding. This stresses the fact that the d and f orbitals are not readily available for strong bond formation with the actenoids. 76

  19. Phosphate barrier on pore-filled cation-exchange membrane for blocking complexing ions in presence of non-complexing ions

    Science.gov (United States)

    Chavan, Vivek; Agarwal, Chhavi; Shinde, Rakesh N.

    2018-06-01

    In present work, an approach has been used to form a phosphate groups bearing surface barrier on a cation-exchange membrane (CEM). Using optimized conditions, the phosphate bearing monomer bis[2-(methacryloyloxy)ethyl] phosphate has been grafted on the surface of the host poly(ethersulfone) membranes using UV light induced polymerization. The detailed characterizations have shown that less than a micron layer of phosphate barrier is formed without disturbing the original microporous structure of the host membrane. The pores of thus formed membrane have been blocked by cationic-gel formed by in situ UV-initiator induced polymerization of 2-acrylamido-2-methyl-1-propane sulphonic acid along with crosslinker ethylene glycol dimethacrylate in the pores of the membrane. UV-initiator is required for pore-filling as UV light would not penetrate the interior matrix of the membrane. The phosphate functionalized barrier membrane has been examined for permselectivity using a mixture of representative complexing Am3+ ions and non-complexing Cs+ ions. This experiment has demonstrated that complex forming Am3+ ions are blocked by phosphate barrier layer while non-complexing Cs+ ions are allowed to pass through the channels formed by the crosslinked cationic gel.

  20. Influence of the substitution of β-cyclodextrins by cationic groups on the complexation of organic anions

    International Nuclear Information System (INIS)

    Hbaieb, S.; Kalfat, R.; Chevalier, Y.; Amdouni, N.; Parrot-Lopez, H.

    2008-01-01

    The inclusion complexation of the organic anion, dansyl-acid, by cationic derivatives of β-cyclodextrin has been investigated. A series of cationic β-cyclodextrins with various positive charge has been synthesized by selective functionalization of the primary face of β-cyclodextrin with amino groups. The complexes were of the 1:1 stoichiometry; the stability constants (K 11 ) have been evaluated from UV-Vis measurements by application of the Benesi-Hildebrand equation. The presence of amino groups increased the complexation ability. β-cyclodextrin fully substituted at the primary face with amino groups showed the strongest inclusion binding ability towards the dansyl-acid guest. The enhanced complexation for anions was ascribed to the cationic amino groups. A simple thermodynamic model of the electrostatic contribution to the complexation is presented

  1. Photochemical deposition of NiCoO x thin films from Ni/Co heteronuclear triketonate complexes

    International Nuclear Information System (INIS)

    Buono-Core, G.E.; Tejos, M.; Cabello, G.; Guzman, N.; Hill, R.H.

    2006-01-01

    UV light irradiation of thin films of a polyketonate Ni/Co heteronuclear complex, NiCo(DBA) 2 [DBA, dibenzoylacetone)], spin coated on Si(1 0 0) substrates produced NiCoO x mixed oxides as amorphous films. On annealing at 600 deg. C under air, the mixed oxide film decomposed to NiO and CoO as indicated by XRD measurements. The morphology of the as-deposited films was examined by AFM analysis showing a smooth surface with low rms roughness values. The ratio of Ni/Co (1.08) present in the film reflects the stoichiometry in the starting compound within the experimental error, as shown by XPS analysis. The large amount of carbon (20.8%) detected on the surface of the film may be due to the presence of phenyl rings in the precursor complex

  2. Influence of the substitution of {beta}-cyclodextrins by cationic groups on the complexation of organic anions

    Energy Technology Data Exchange (ETDEWEB)

    Hbaieb, S. [U.R. Physico-Chimie des Materiaux Solides, Faculte des Sciences de Tunis, Manar II, 2092 Tunis (Tunisia)], E-mail: Souhairabouchaira@yahoo.fr; Kalfat, R. [U.R. Physico-Chimie des Materiaux Solides, Faculte des Sciences de Tunis, Manar II, 2092 Tunis (Tunisia); Chevalier, Y. [Laboratoire d' Automatique et de Genie des Procedes (LAGEP), UMR 5007 CNRS-Universite Claude Bernard Lyon 1, 69622 Villeurbanne (France)], E-mail: chevalier@lagep.univ-lyon1.fr; Amdouni, N. [U.R. Physico-Chimie des Materiaux Solides, Faculte des Sciences de Tunis, Manar II, 2092 Tunis (Tunisia); Parrot-Lopez, H. [Institut de Chimie et Biochimie Moleculaires et Supramoleculaires (ICBMS), UMR 5246 CNRS-Universite Claude Bernard Lyon 1, 69622 Villeurbanne (France)], E-mail: helene.parrot@univ-lyon1.fr

    2008-07-01

    The inclusion complexation of the organic anion, dansyl-acid, by cationic derivatives of {beta}-cyclodextrin has been investigated. A series of cationic {beta}-cyclodextrins with various positive charge has been synthesized by selective functionalization of the primary face of {beta}-cyclodextrin with amino groups. The complexes were of the 1:1 stoichiometry; the stability constants (K{sub 11}) have been evaluated from UV-Vis measurements by application of the Benesi-Hildebrand equation. The presence of amino groups increased the complexation ability. {beta}-cyclodextrin fully substituted at the primary face with amino groups showed the strongest inclusion binding ability towards the dansyl-acid guest. The enhanced complexation for anions was ascribed to the cationic amino groups. A simple thermodynamic model of the electrostatic contribution to the complexation is presented.

  3. Synthesis and characterization of a homogeneous and silica supported homoleptic cationic tungsten(vi) methyl complex: application in olefin metathesis

    KAUST Repository

    Dey, Raju

    2016-08-19

    A method for the synthesis of a homogeneous cationic tungsten(VI)penta-methyl complex [(WMe5)(+)(C6F5)(3)BMe-] from neutral tungstenhexamethyl (WMe6) and a silica supported cationic tungstentetramethyl complex [( Si-O-)WMe4+ (C6F5)(3)BMe-] from a neutral silica supported tungstenpentamethyl complex [( Si-O-)WMe5] is described. In both cases a direct demethylation using the B(C6F5)(3) reagent was used. The aforesaid complexes were characterized by liquid or solid state NMR spectroscopy. Interestingly, the homogeneous cationic complex [(WMe5)(+)(C6F5)(3)BMe-] shows moderate activity whereas the supported cationic complex [( Si-O-)WMe4+(C6F5)(3)BMe-] exhibits good activity in olefin metathesis reactions.

  4. Synthesis and characterization of a homogeneous and silica supported homoleptic cationic tungsten(vi) methyl complex: application in olefin metathesis

    KAUST Repository

    Dey, Raju; Samantaray, Manoja; Poater, Albert; Hamieh, Ali Imad Ali; Kavitake, Santosh Giridhar; Abou-Hamad, Edy; Callens, Emmanuel; Emwas, Abdul-Hamid M.; Cavallo, Luigi; Basset, Jean-Marie

    2016-01-01

    A method for the synthesis of a homogeneous cationic tungsten(VI)penta-methyl complex [(WMe5)(+)(C6F5)(3)BMe-] from neutral tungstenhexamethyl (WMe6) and a silica supported cationic tungstentetramethyl complex [( Si-O-)WMe4+ (C6F5)(3)BMe-] from a neutral silica supported tungstenpentamethyl complex [( Si-O-)WMe5] is described. In both cases a direct demethylation using the B(C6F5)(3) reagent was used. The aforesaid complexes were characterized by liquid or solid state NMR spectroscopy. Interestingly, the homogeneous cationic complex [(WMe5)(+)(C6F5)(3)BMe-] shows moderate activity whereas the supported cationic complex [( Si-O-)WMe4+(C6F5)(3)BMe-] exhibits good activity in olefin metathesis reactions.

  5. Synthesis, structure and DFT conformation analysis of CpNiX(NHC) and NiX2(NHC)2 (X = SPh or Br) complexes

    Science.gov (United States)

    Malan, Frederick P.; Singleton, Eric; van Rooyen, Petrus H.; Conradie, Jeanet; Landman, Marilé

    2017-11-01

    The synthesis, density functional theory (DFT) conformational study and structure analysis of novel two-legged piano stool Ni N-heterocyclic carbene (NHC) complexes and square planar Ni bis-N-heterocyclic carbene complexes, all containing either bromido- or thiophenolato ligands, are described. [CpNi(SPh)(NHC)] complexes were obtained from the neutral 18-electron [CpNiBr(NHC)] complexes by substitution of a bromido ligand with SPh, using NEt3 as a base to abstract the proton of HSPh. The 16-electron biscarbene complexes [Ni(SPh)2{NHC}2] were isolated when an excess of HSPh was added to the reaction mixture. Biscarbene complexes of the type [NiBr2(NHC)2] were obtained in the reaction of NiCp2 with a slight excess of the specific imidazolium bromide salt. The molecular and electronic structures of the mono- and bis-N-heterocyclic carbene complexes have been analysed using single crystal diffraction and density functional theory (DFT) calculations, to give insight into their structural properties.

  6. Raman spectroscopy of DNA-metal complexes. I. Interactions and conformational effects of the divalent cations: Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Pd, and Cd.

    Science.gov (United States)

    Duguid, J; Bloomfield, V A; Benevides, J; Thomas, G J

    1993-11-01

    Interactions of divalent metal cations (Mg2+, Ca2+, Ba2+, Sr2+, Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) with DNA have been investigated by laser Raman spectroscopy. Both genomic calf-thymus DNA (> 23 kilobase pairs) and mononucleosomal fragments (160 base pairs) were employed as targets of metal interaction in solutions containing 5 weight-% DNA and metal:phosphate molar ratios of 0.6:1. Raman difference spectra reveal that transition metal cations (Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) induce the greatest structural changes in B-DNA. The Raman (vibrational) band differences are extensive and indicate partial disordering of the B-form backbone, reduction in base stacking, reduction in base pairing, and specific metal interaction with acceptor sites on the purine (N7) and pyrimidine (N3) rings. Many of the observed spectral changes parallel those accompanying thermal denaturation of B-DNA and suggest that the metals link the bases of denatured DNA. While exocyclic carbonyls of dT, dG, and dC may stabilize metal ligation, correlation plots show that perturbations of the carbonyls are mainly a consequence of metal-induced denaturation of the double helix. Transition metal interactions with the DNA phosphates are weak in comparison to interactions with the bases, except in the case of Cu2+, which strongly perturbs both base and phosphate group vibrations. On the other hand, the Raman signature of B-DNA is largely unperturbed by Mg2+, Ca2+, Sr2+, and Ba2+, suggesting much weaker interactions of the alkaline earth metals with both base and phosphate sites. A notable exception is a moderate perturbation by alkaline earths of purine N7 sites in 160-base pair DNA, with Ca2+ causing the greatest effect. Correlation plots demonstrate a strong interrelationship between perturbations of Raman bands assigned to ring vibrations of the bases and those of bands assigned to exocyclic carbonyls and backbone phosphodiester groups. However, strong correlations do not occur between

  7. Structural, vibrational and morphological properties of layered double hydroxides containing Ni2+, Zn2+, Al3+ and Zr4+ cations

    International Nuclear Information System (INIS)

    Bezerra, Débora M.; Rodrigues, João E.F.S.; Assaf, Elisabete M.

    2017-01-01

    Layered double hydroxides are anionic clays with formula [M II 1−x M III x (OH) 2 ] q+ [A n− ] q/n ·mH 2 O, finding possible uses as catalyst support, adsorbents and so on. In this paper, we address the phase formation of layered double hydroxides containing Ni 2+ , Zn 2+ , Al 3+ and Zr 4+ cations, namely, NiZn-Al, NiZn-AlZr and NiZn-Zr compositions obtained by the coprecipitation method. Such systems were characterized by X-ray diffraction, confirming the phase formation for NiZn-Al and NiZn-AlZr samples. Infrared and Raman spectroscopies elucidated the anion and water molecules occurrence in the interlayer. Nitrogen physisorption (BET method) determined the presence of pores and specific surface area. The isotherm shapes were Type IV, according to the IUPAC, and represent a mesoporous structure. A morphological study was performed by means of scanning and transmission electron microscopies, and particle size values of 120, 131 and 235 nm for NiZn-Al, NiZn-AlZr and NiZn-Zr, respectively, were determined. Thermogravimetric analysis of the decomposition of the systems revealed that their complete disintegration occurred at ~ 450 °C and resulted in mixed oxides.

  8. DNA complexes with Ni nanoparticles: structural and functional properties

    Energy Technology Data Exchange (ETDEWEB)

    Tatarinova, Olga N.; Smirnov, Igor P. [Research Institute for Physico-Chemical Medicine of the Federal Medical-Biological Agency of the Russian Federation (Russian Federation); Safenkova, Irina V. [A.N. Bach Institute of Biochemistry (Russian Federation); Varizhuk, Anna M.; Pozmogova, Galina E., E-mail: pozmge@gmail.com [Research Institute for Physico-Chemical Medicine of the Federal Medical-Biological Agency of the Russian Federation (Russian Federation)

    2012-10-15

    Supramolecular complexes of biopolymers based on magnetic nanoparticles play an important role in creation of biosensors, implementation of theragnostic and gene therapeutic methods and biosafety evaluation. We investigated the impact of DNA interactions with nanoparticles of nickel (nNi) on the integrity and functionality of DNA. Data obtained by mass spectrometry, electrophoresis, TEM and AFM microscopy techniques, bacterial transformation, and real-time PCR provide evidence that ssDNA and plasmid DNA (pDNA) efficiently form complexes with nNi. AFM data suggest that the complexes are necklace-type structures, in which nanoparticles are randomly distributed along the DNA chains, rather than highly entangled clot-type structures. After desorption, observed DNA characteristics in bioanalytical and biological systems remain unchanged. Only supercoiled pDNA was nicked, but remained, as well as a plasmid-nNi complex, active in expression vector assays. These results are very important for creation of new methods of DNA immobilization and controlled manipulation.

  9. DNA complexes with Ni nanoparticles: structural and functional properties

    International Nuclear Information System (INIS)

    Tatarinova, Olga N.; Smirnov, Igor P.; Safenkova, Irina V.; Varizhuk, Anna M.; Pozmogova, Galina E.

    2012-01-01

    Supramolecular complexes of biopolymers based on magnetic nanoparticles play an important role in creation of biosensors, implementation of theragnostic and gene therapeutic methods and biosafety evaluation. We investigated the impact of DNA interactions with nanoparticles of nickel (nNi) on the integrity and functionality of DNA. Data obtained by mass spectrometry, electrophoresis, TEM and AFM microscopy techniques, bacterial transformation, and real-time PCR provide evidence that ssDNA and plasmid DNA (pDNA) efficiently form complexes with nNi. AFM data suggest that the complexes are necklace-type structures, in which nanoparticles are randomly distributed along the DNA chains, rather than highly entangled clot-type structures. After desorption, observed DNA characteristics in bioanalytical and biological systems remain unchanged. Only supercoiled pDNA was nicked, but remained, as well as a plasmid–nNi complex, active in expression vector assays. These results are very important for creation of new methods of DNA immobilization and controlled manipulation.

  10. pH-Dependent isotope exchange and hydrogenation catalysed by water-soluble NiRu complexes as functional models for [NiFe]hydrogenases.

    Science.gov (United States)

    Kure, Bunsho; Matsumoto, Takahiro; Ichikawa, Koji; Fukuzumi, Shunichi; Higuchi, Yoshiki; Yagi, Tatsuhiko; Ogo, Seiji

    2008-09-21

    The pH-dependent hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes and hydrogenation of the carbonyl compounds have been investigated with water-soluble bis(mu-thiolate)(mu-hydride)NiRu complexes, Ni(II)(mu-SR)(2)(mu-H)Ru(II) {(mu-SR)(2) = N,N'-dimethyl-N,N'-bis(2-mercaptoethyl)-1,3-propanediamine}, as functional models for [NiFe]hydrogenases. In acidic media (at pH 4-6), the mu-H ligand of the Ni(II)(mu-SR)(2)(mu-H)Ru(II) complexes has H(+) properties, and the complexes catalyse the hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes. A mechanism of the hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes through a low-valent Ni(I)(mu-SR)(2)Ru(I) complex is proposed. In contrast, in neutral-basic media (at pH 7-10), the mu-H ligand of the Ni(II)(mu-SR)(2)(mu-H)Ru(II) complexes acts as H(-), and the complexes catalyse the hydrogenation of carbonyl compounds.

  11. Infrared multiple photon dissociation action spectroscopy of alkali metal cation-cyclen complexes: Effects of alkali metal cation size on gas-phase conformation

    NARCIS (Netherlands)

    Austin, C.A.; Chen, Y.; Kaczan, C.M.; Berden, G.; Oomens, J.; Rodgers, M.T.

    2013-01-01

    The gas-phase structures of alkali metal cationized complexes of cyclen (1,4,7,10-tetraazacyclododecane) are examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and electronic structure theory calculations. The measured IRMPD action spectra of four M+(cyclen) complexes are

  12. Determination of Ni{sup 2+} using an equilibrium ion exchange technique: Important chemical factors and applicability to environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Worms, Isabelle A.M. [CABE - Analytical and Biophysical Environmental Chemistry, University of Geneva, 30 quai Ernest Ansermet 1211 Geneva 4 (Switzerland); Wilkinson, Kevin J. [Department of Chemistry, University of Montreal C.P. 6128, succursale Centre-ville Montreal, H3C 3J7 (Canada)], E-mail: KJ.Wilkinson@umontreal.ca

    2008-05-26

    In natural waters, the determination of free metal concentrations is a key parameter for studying bioavailability. Unfortunately, few analytical tools are available for determining Ni speciation at the low concentrations found in natural waters. In this paper, an ion exchange technique (IET) that employs a Dowex resin is evaluated for its applicability to measure [Ni{sup 2+}] in freshwaters. The presence of major cations (e.g. Na, Ca and Mg) reduced both the times that were required for equilibration and the partition coefficient to the resin ({lambda}{sup '}{sub Ni}). IET measurements of [Ni{sup 2+}] in the presence of known ligands (citrate, diglycolate, sulfoxine, oxine and diethyldithiocarbamate) were verified by thermodynamic speciation models (MINEQL{sup +} and VisualMINTEQ). Results indicated that the presence of hydrophobic complexes (e.g. Ni(DDC){sub 2}{sup 0}) lead to an overestimation of the Ni{sup 2+} fraction. On the other hand, [Ni{sup 2+}] measurements that were made in the presence of amphiphilic complexes formed with humic substances (standard aquatic humic acid (SRHA) and standard aquatic fulvic acid (SRFA)) were well correlated to free ion concentrations that were calculated using a NICA-DONNAN model. An analytical method is also presented here to reduce the complexity of the calibration (due to the presence of many other cations) for the use of Dowex equilibrium ion exchange technique in natural waters.

  13. Enhanced splicing correction effect by an oligo-aspartic acid-PNA conjugate and cationic carrier complexes.

    Science.gov (United States)

    Bae, Yun Mi; Kim, Myung Hee; Yu, Gwang Sig; Um, Bong Ho; Park, Hee Kyung; Lee, Hyun-il; Lee, Kang Taek; Suh, Yung Doug; Choi, Joon Sig

    2014-02-10

    Peptide nucleic acids (PNAs) are synthetic structural analogues of DNA and RNA. They recognize specific cellular nucleic acid sequences and form stable complexes with complementary DNA or RNA. Here, we designed an oligo-aspartic acid-PNA conjugate and showed its enhanced delivery into cells with high gene correction efficiency using conventional cationic carriers, such as polyethylenimine (PEI) and Lipofectamine 2000. The negatively charged oligo-aspartic acid-PNA (Asp(n)-PNA) formed complexes with PEI and Lipofectamine, and the resulting Asp(n)-PNA/PEI and Asp(n)-PNA/Lipofectamine complexes were introduced into cells. We observed significantly enhanced cellular uptake of Asp(n)-PNA by cationic carriers and detected an active splicing correction effect even at nanomolar concentrations. We found that the splicing correction efficiency of the complex depended on the kind of the cationic carriers and on the number of repeating aspartic acid units. By enhancing the cellular uptake efficiency of PNAs, these results may provide a novel platform technology of PNAs as bioactive substances for their biological and therapeutic applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Ni(II) complexes of dithiophosphonic acids

    Indian Academy of Sciences (India)

    aDepartment of Chemistry, Science and Research Branch, Islamic Azad ... The compounds were characterized by 1H, 13C and 31P NMR, IR spectroscopy and elemental analysis. The ... design and synthesize Ni(II) complexes with new ..... Yield: 86%. ..... 28 65. 18. Greenwood D 1989 Antimicrobial chemotherapy (New.

  15. Isolation of homoleptic platinum oxyanionic complexes with doubly protonated diazacrown cation

    Science.gov (United States)

    Vasilchenko, Danila; Tkachev, Sergey; Baidina, Iraida; Romanenko, Galina; Korenev, Sergey

    2017-02-01

    Doubly protonated diazacrown ether cation (1,4,10,13-tetraoxa-7,16-diazoniacyclooctadecane DCH22+) was used for the efficient isolation of the homoleptic platinum complexes [Pt(NO3)6]2- and [Pt(C2O4)2]2- to crystalline solid phases from solutions containing mixtures of related platinum complexes. DCH22+ molecules in nitric acid solution were shown to prevent the condensation of mononuclear [Pt(H2O)n(NO3)6-n]n-2 species.

  16. Pearl-necklace complexes of flexible polyanions with neutral-cationic diblock copolymers

    NARCIS (Netherlands)

    Golinska, M.D.; Wolf, de F.A.; Cohen Stuart, M.A.; Hernandez Garcia, A.; Vries, de R.J.

    2013-01-01

    We study the complexation of very asymmetric diblock copolymers (consisting of a cationic block of 12 lysines connected to a 400 amino acid long hydrophilic polypeptide block with a net charge that is nearly zero) with oppositely charged sodium poly(acrylic acid) (NaPAA) with a range of molar masses

  17. Zeaxanthin Radical Cation Formation in Minor Light-Harvesting Complexes of Higher Plant Antenna

    Energy Technology Data Exchange (ETDEWEB)

    Avenson, Thomas H.; Ahn, Tae Kyu; Zigmantas, Donatas; Niyogi, Krishna K.; Li, Zhirong; Ballottari, Matteo; Bassi, Roberto; Fleming, Graham R.

    2008-01-31

    Previous work on intact thylakoid membranes showed that transient formation of a zeaxanthin radical cation was correlated with regulation of photosynthetic light-harvesting via energy-dependent quenching. A molecular mechanism for such quenching was proposed to involve charge transfer within a chlorophyll-zeaxanthin heterodimer. Using near infrared (880-1100 nm) transient absorption spectroscopy, we demonstrate that carotenoid (mainly zeaxanthin) radical cation generation occurs solely in isolated minor light-harvesting complexes that bind zeaxanthin, consistent with the engagement of charge transfer quenching therein. We estimated that less than 0.5percent of the isolated minor complexes undergo charge transfer quenching in vitro, whereas the fraction of minor complexes estimated to be engaged in charge transfer quenching in isolated thylakoids was more than 80 times higher. We conclude that minor complexes which bind zeaxanthin are sites of charge transfer quenching in vivo and that they can assume Non-quenching and Quenching conformations, the equilibrium LHC(N)<--> LHC(Q) of which is modulated by the transthylakoid pH gradient, the PsbS protein, and protein-protein interactions.

  18. Novel Reactivity Of The Cationic Complex

    International Nuclear Information System (INIS)

    Wang, J.; Dash, A.K.; Eisen, AM.; Berthet, J.C.; Ephritikhine, M.

    2002-01-01

    The catalytic chemistry of electrophilic d 0 /f organometallic complexes is nowadays under intense investigation, reaching a high level of sophistication. General aspects concerning these complexes are concentrated for most studies to the functionalization of unsaturated organic molecules. To cite an instance, the actinide-promoted oligomerization of terminal alkynes is of essential present concern since it may introduce to a diversity of organic enynes and oligoacetylene products that are valuable synthons for the synthesis of natural products. Enynes are the simplest oligomerization products of alkynes. We have demonstrated that organoactinides complexes of the type [Cp* 2 AnMe 2 AnMe 2 ] (Cp* = C 5 Me 5 ; An = U, Th) are active catalysts for the linear oligomerization of terminal alkynes and the extent of oligomerization was found to be strongly dependent on the electronic and steric properties of the alkyne substituents. Bulky alkynes were reacted with high regioselectivity toward dimer and/or trimers whereas for non-bulky alkynes, these compounds were transformed into oligomers with a total deficiency of regioselectivity. The addition of primary amines to the catalytic cycle, for An = Th, granted the chemoselective formation of dimers, chemoselectively, whereas for An = U, this control was not succeeded. In distinction to the neutral organoactinide complexes, homogeneous cationic d 0 /f n actinide complexes have been used as in the homogeneous polymerization of olefins as extremely active catalysts. Hence, the catalytic alkyne oligomerization is a opportune route to explore insertions and σ-bond metathesis reactivity of complexes. We have recently shown that the reaction of terminal alkynes (RC≡CH), promoted by [(Et 2 N) 3 U][BPh 4 ], in toluene, produces efficiently mostly the gem dimers (for R = Me, i Pr and n Bu) as the major products, whereas for bulky alkynes (R = t MS or t Bu) small amounts of the cis dimer was concomitantly obtained. A plausible

  19. Competition effect of some metal ions on the complexation of strontium with humic acid. Vol. 4

    Energy Technology Data Exchange (ETDEWEB)

    Helal, A A; Aly, H F; Imam, D M; Khalifa, S M [Atomic Energy Authorty, Cairo (Egypt)

    1996-03-01

    Interaction of radioactive strontium with humic acid present in water streams is of main importance to learn about the fate of strontium in case of accidental release. In this work, formation of Sr-humate precipitate was studied radiometrically and colorimetric at different PH`s. The investigations indicated that formation of the precipitated complex increases with increasing strontium concentration till saturation. The competition effect of other cations in solution such as Ca, Mg, Ba, and Ni was investigated. The humate complexes of these cations were studied colorimetric, and the competition behaviour was investigated using the radiotracer of strontium. The results indicated that presence of Ba, Mg and Ni decreases the Sr-humate complex, while increasing Ca concentration enhances precipitation of Sr with humic acid. 10 figs.

  20. Design of Nickel-Based Cation-Disordered Rock-Salt Oxides: The Effect of Transition Metal (M = V, Ti, Zr) Substitution in LiNi0.5M0.5O2 Binary Systems.

    Science.gov (United States)

    Cambaz, Musa Ali; Vinayan, Bhaghavathi P; Euchner, Holger; Johnsen, Rune E; Guda, Alexander A; Mazilkin, Andrey; Rusalev, Yury V; Trigub, Alexander L; Gross, Axel; Fichtner, Maximilian

    2018-06-20

    Cation-disordered oxides have been ignored as positive electrode material for a long time due to structurally limited lithium insertion/extraction capabilities. In this work, a case study is carried out on nickel-based cation-disordered Fm3 ̅m LiNi 0.5 M 0.5 O 2 positive electrode materials. The present investigation targets tailoring the electrochemical properties for nickel-based cation-disordered rock-salt by electronic considerations. The compositional space for binary LiM +3 O 2 with metals active for +3/+4 redox couples is extended to ternary oxides with LiA 0.5 B 0.5 O 2 with A = Ni 2+ and B = Ti 4+ , Zr 4+ , and V +4 to assess the impact of the different transition metals in the isostructural oxides. The direct synthesis of various new unknown ternary nickel-based Fm3̅ m cation-disordered rock-salt positive electrode materials is presented with a particular focus on the LiNi 0.5 V 0.5 O 2 system. This positive electrode material for Li-ion batteries displays an average voltage of ∼2.55 V and a high discharge capacity of 264 mAhg -1 corresponding to 0.94 Li. For appropriate cutoff voltages, a long cycle life is achieved. The charge compensation mechanism is probed by XANES, confirming the reversible oxidation and reduction of V 4+ /V 5+ . The enhancement in the electrochemical performances within the presented compounds stresses the importance of mixed cation-disordered transition metal oxides with different electronic configuration.

  1. Electronic structure of the [MNH2]+ (M = Sc-Cu) complexes.

    Science.gov (United States)

    Hendrickx, Marc F A; Clima, Sergiu

    2006-11-23

    B3LYP geometry optimizations for the [MNH2]+ complexes of the first-row transition metal cations (Sc+-Cu+) were performed. Without any exception the ground states of these unsaturated amide complexes were calculated to possess planar geometries. CASPT2 binding energies that were corrected for zero-point energies and including relativistic effects show a qualitative trend across the series that closely resembles the experimental observations. The electronic structures for the complexes of the early and middle transition metal cations (Sc+-Co+) differ from the electronic structures derived for the complexes of the late transition metal cations (Ni+ and Cu+). For the former complexes the relative higher position of the 3d orbitals above the singly occupied 2p(pi) HOMO of the uncoordinated NH2 induces an electron transfer from the 3d shell to 2p(pi). The stabilization of the 3d orbitals from the left to the right along the first-row transition metal series causes these orbitals to become situated below the HOMO of the NH2 ligand for Ni+ and Cu+, preventing a transfer from occurring in the [MNH2]+ complexes of these metal cations. Analysis of the low-lying states of the amide complexes revealed a rather unique characteristic of their electronic structures that was found across the entire series. Rather exceptionally for the whole of chemistry, pi-type interactions were calculated to be stronger than the corresponding sigma-type interactions. The origin of this extraordinary behavior can be ascribed to the low-lying sp2 lone pair orbital of the NH2 ligand with respect to the 3d level.

  2. Molecular and supramolecular characterization of Ni(II)/losartan hydrophobic nanoprecipitate

    Science.gov (United States)

    Nascimento, Lorrayne O.; Goulart, Pedro P.; Correa, Jéssyca L.; Abrishamkar, Afshin; Da Silva, Jeferson G.; Mangrich, Antonio S.; de França, Amanda A.; Denadai, Ângelo M. L.

    2014-09-01

    In this work, a contribution to understanding of the formation of metal(II)/losartan hydrophobic nanoprecipitate is reported. A Ni(II)/Los system was prepared and characterized in solid state and in solution. Solubility studies confirmed the formation of hydrophobic precipitate. Obtained spectroscopic data suggest a sort of coordination between tetrazolic ring as well as OH, and a D4h geometry around the nickel cation. Thermodynamic studies demonstrated that complexation is a stepwise process, with equal enthalpic and entropic contributions for free energy of complexation. DLS and zeta potential titrations indicate the formation of stable nanoparticles of size and charge dependent on the molar ratio. Finally, rheological studies demonstrate a Bingham plastic behavior for Ni(II)/Los suspension.

  3. Catalytic Hydroamination of Alkynes and Norbornene with Neutral and Cationic Tantalum Imido Complexes

    Science.gov (United States)

    Anderson, Laura L.; Arnold, John; Bergman, Robert G.

    2005-01-01

    Several tantalum imido complexes have been synthesized and shown to efficiently catalyze the hydroamination of internal and terminal alkynes. An unusual hydroamination/hydroarylation reaction of norbornene catalyzed by a highly electrophilic cationic tantalum imido complex is also reported. Factors affecting catalyst activity and selectivity are discussed along with mechanistic insights gained from stoichiometric reactions. PMID:15255680

  4. Liquid-solid extraction of metallic cations by cationic amphiphiles

    International Nuclear Information System (INIS)

    Mueller, Wolfram; Sievers, Torsten K.; Zemb, Thomas; Diat, Olivier; Sievers, Torsten K.; Dejugnat, Christophe

    2012-01-01

    In the field of selective metal ion separation, liquid-liquid extraction is usually conducted through an emulsion mixing of hydrophobic complexants dispersed in an organic phase and acidic water containing the ionic species. Recently, it has been shown that amphiphilic complexants could influence strongly extraction efficiency by enhancing the interfacial interaction between the metal ion in the aqueous and the complexant in the organic phase. Moreover, these amphiphiles can also substitute the organic phase if an appropriate aliphatic chain is chosen. The dispersion of such amphiphilic complexants in an aqueous solution of salt mixtures is not only attractive for studying specific interactions but also to better the understanding of complex formation in aqueous solution of multivalent metal ions, such as lanthanides and actinides. This understanding is of potential interest for a broad range of industries including purification of rare earth metals and pollute treatment e.g. of fission byproducts. This principle can also be applied to liquid-solid extraction, where the final state of the separation is a solid phase containing the selectively extracted ions. Indeed, a novel solid-liquid extraction method exploits the selective precipitation of metal ions from an aqueous salt mixture using a cationic surfactant, below its Krafft point (temperature below which the long aliphatic chains of surfactant crystallize). This technique has been proven to be highly efficient for the separation of actinides and heavy metal using long chain ammonium or pyridinium amphiphiles. The most important point in this process is the recognition of cationic metal ions by cationic surfactants. By computing the free energy of the polar head group per micelle as a function of the different counter-anions, we have demonstrated for the first time that different interactions exist between the micellar surface and the ions. These interactions depend on the nature of the cation but also on

  5. Structural and energetic study of cation-π-cation interactions in proteins.

    Science.gov (United States)

    Pinheiro, Silvana; Soteras, Ignacio; Gelpí, Josep Lluis; Dehez, François; Chipot, Christophe; Luque, F Javier; Curutchet, Carles

    2017-04-12

    Cation-π interactions of aromatic rings and positively charged groups are among the most important interactions in structural biology. The role and energetic characteristics of these interactions are well established. However, the occurrence of cation-π-cation interactions is an unexpected motif, which raises intriguing questions about its functional role in proteins. We present a statistical analysis of the occurrence, composition and geometrical preferences of cation-π-cation interactions identified in a set of non-redundant protein structures taken from the Protein Data Bank. Our results demonstrate that this structural motif is observed at a small, albeit non-negligible frequency in proteins, and suggest a preference to establish cation-π-cation motifs with Trp, followed by Tyr and Phe. Furthermore, we have found that cation-π-cation interactions tend to be highly conserved, which supports their structural or functional role. Finally, we have performed an energetic analysis of a representative subset of cation-π-cation complexes combining quantum-chemical and continuum solvation calculations. Our results point out that the protein environment can strongly screen the cation-cation repulsion, leading to an attractive interaction in 64% of the complexes analyzed. Together with the high degree of conservation observed, these results suggest a potential stabilizing role in the protein fold, as demonstrated recently for a miniature protein (Craven et al., J. Am. Chem. Soc. 2016, 138, 1543). From a computational point of view, the significant contribution of non-additive three-body terms challenges the suitability of standard additive force fields for describing cation-π-cation motifs in molecular simulations.

  6. Hydride Reactivity of Ni-II-X-Ni-II Entities : Mixed-Valent Hydrido Complexes and Reversible Metal Reduction

    NARCIS (Netherlands)

    Gehring, Henrike; Metzinger, Ramona; Herwig, Christian; Intemann, Julia; Harder, Sjoerd; Limberg, Christian

    After the lithiation of PYR-H2 (PYR2-=[{NC(Me)C(H)C(Me)NC6H3(iPr)2}2(C5H3N)]2-), which is the precursor of an expanded beta-diketiminato ligand system with two binding pockets, its reaction with [NiBr2(dme)] led to a dinuclear nickel(II)bromide complex, [(PYR)Ni(mu-Br)NiBr] (1). The bridging bromide

  7. pH-Dependent isotope exchange and hydrogenation catalysed by water-soluble NiRu complexes as functional models for [NiFe]hydrogenases

    OpenAIRE

    Kure, Bunsho; Matsumoto, Takahiro; Ichikawa, Koji; Fukuzumi, Shunichi; Higuchi, Yoshiki; Yagi, Tatsuhiko; Ogo, Seiji

    2008-01-01

    The pH-dependent hydrogen isotope exchange reaction between gaseous isotopes and medium isotopes and hydrogenation of the carbonyl compounds have been investigated with water-soluble bis(mu-thiolate)(mu-hydride)NiRu complexes, Ni(II)(mu-SR)(2)(mu-H)Ru(II) {(mu-SR)(2) = N,N'-dimethyl-N,N'-bis(2-mercaptoethyl)-1,3-propanediamine}, as functional models for [NiFe]hydrogenases. In acidic media (at pH 4-6), the mu-H ligand of the Ni(II)(mu-SR)(2)(mu-H)Ru(II) complexes has H(+) properties, and the c...

  8. Cation and anion dependence of stable geometries and stabilization energies of alkali metal cation complexes with FSA(-), FTA(-), and TFSA(-) anions: relationship with physicochemical properties of molten salts.

    Science.gov (United States)

    Tsuzuki, Seiji; Kubota, Keigo; Matsumoto, Hajime

    2013-12-19

    Stable geometries and stabilization energies (Eform) of the alkali metal complexes with bis(fluorosulfonyl)amide, (fluorosulfonyl)(trifluoromethylslufonyl)amide and bis(trifluoromethylsulfonyl)amide (FSA(-), FTA(-) and TFSA(-)) were studied by ab initio molecular orbital calculations. The FSA(-) complexes prefer the bidentate structures in which two oxygen atoms of two SO2 groups have contact with the metal cation. The FTA(-) and TFSA(-) complexes with Li(+) and Na(+) prefer the bidentate structures, while the FTA(-) and TFSA(-) complexes with Cs(+) prefer tridentate structures in which the metal cation has contact with two oxygen atoms of an SO2 group and one oxygen atom of another SO2 group. The two structures are nearly isoenergetic in the FTA(-) and TFSA(-) complexes with K(+) and Rb(+). The magnitude of Eform depends on the alkali metal cation significantly. The Eform calculated for the most stable TFSA(-) complexes with Li(+), Na(+), K(+), Rb(+) and Cs(+) cations at the MP2/6-311G** level are -137.2, -110.5, -101.1, -89.6, and -84.1 kcal/mol, respectively. The viscosity and ionic conductivity of the alkali TFSA molten salts have strong correlation with the magnitude of the attraction. The viscosity increases and the ionic conductivity decreases with the increase of the attraction. The melting points of the alkali TFSA and alkali BETA molten salts also have correlation with the magnitude of the Eform, which strongly suggests that the magnitude of the attraction play important roles in determining the melting points of these molten salts. The anion dependence of the Eform calculated for the complexes is small (less than 2.9 kcal/mol). This shows that the magnitude of the attraction is not the cause of the low melting points of alkali FTA molten salts compared with those of corresponding alkali TFSA molten salts. The electrostatic interactions are the major source of the attraction in the complexes. The electrostatic energies for the most stable TFSA

  9. Self-Organization of +-Crown Ether Derivatives into Double-Columnar Arrays Controlled by Supramolecular Isomers of Hydrogen-Bonded Anionic Biimidazolate Ni Complexes

    Directory of Open Access Journals (Sweden)

    Makoto Tadokoro

    2012-01-01

    Full Text Available Anionic tris (biimidazolate nickelate (II ([Ni(Hbim3]−, which is a hydrogen-bonding (H-bonding molecular building block, undergoes self-organization into honeycomb-sheet superstructures connected by complementary intermolecular H-bonds. The crystal obtained from the stacking of these sheets is assembled into channel frameworks, approximately 2 nm wide, that clathrate two cationic K+-crown ether derivatives organised into one-dimensional (1D double-columnar arrays. In this study, we have shown that all five cationic guest-included crystals form nanochannel structures that clathrate the 1-D double-columnar arrays of one of the four types of K+-crown ether derivatives, one of which induces a polymorph. This is accomplished by adaptably fitting two types of anionic [Ni(Hbim3]− host arrays. One is a ΔΛ−ΔΛ−ΔΛ⋯ network with H-bonded linkages alternating between the two different optical isomers of the Δ and Λ types with flexible H-bonded [Ni(Hbim3]−. The other is a ΔΔΔ−ΛΛΛ⋯ network of a racemate with 1-D H-bonded arrays of the same optical isomer for each type. Thus, [Ni(Hbim3]− can assemble large cations such as K+ crown-ether derivatives into double-columnar arrays by highly recognizing flexible H-bonding arrangements with two host networks of ΔΛ−ΔΛ−ΔΛ⋯ and ΔΔΔ−ΛΛΛ⋯.

  10. Cationic Amphiphilic Tris-Cyclometalated Iridium(III) Complexes Induce Cancer Cell Death via Interaction with Ca2+-Calmodulin Complex.

    Science.gov (United States)

    Hisamatsu, Yosuke; Suzuki, Nozomi; Masum, Abdullah-Al; Shibuya, Ai; Abe, Ryo; Sato, Akira; Tanuma, Sei-Ichi; Aoki, Shin

    2017-02-15

    In our previous paper, we reported on the preparation of some cationic amphiphilic Ir complexes (2c, 2d) containing KKGG peptides that induce and detect cell death of Jurkat cells. Mechanistic studies suggest that 2c interacts with anionic molecules and/or membrane receptors on the cell surface to trigger an intracellular Ca 2+ response, resulting in the induction of cell death, accompanied by membrane disruption. We have continued the studies of cell death of Jurkat cells induced by 2c and found that xestospongin C, a selective inhibitor of an inositol 1,4,5-trisphosphate receptor located on the endoplasmic reticulum (ER), reduces the cytotoxicity of 2c, suggesting that 2c triggers the release of Ca 2+ from the ER, leading to an increase in the concentration of cytosolic Ca 2+ , thus inducing cell death. Moreover, we synthesized a series of new amphiphilic cationic Ir complexes 5a-c containing photoreactive 3-trifluoromethyl-3-phenyldiazirine (TFPD) groups, in an attempt to identify the target molecules of 2c. Interestingly, it was discovered that a TFPD group functions as a triplet quencher of Ir complexes. It was also found that 5b is useful as a turn-on phosphorescent probe of acidic proteins such as bovine serum albumin (BSA) (pI = 4.7) and their complexation was confirmed by luminescence titrations and SDS-PAGE of photochemical products between them. These successful results allowed us to carry out photoaffinity labeling of the target biomolecules of 5b (2c and analogues thereof) in Jurkat cells. A proteomic analysis of the products obtained by the photoirradiation of 5b with Jurkat cells suggests that the Ca 2+ -binding protein "calmodulin (CaM)" is one of target proteins of the Ir complexes. Indeed, 5b was found to interact with the Ca 2+ -CaM complex, as evidenced by luminescence titrations and the results of photochemical reactions of 5b with CaM in the presence of Ca 2+ (SDS-PAGE). A plausible mechanism for cell death induced by a cationic amphiphilic Ir

  11. The complex transfer reaction (14C, 15O) on Ni, Zn and Ge targets: existence and mass of 69Ni

    International Nuclear Information System (INIS)

    Dessagne, P.; Bernas, M.; Langevin, M.; Pougheon, F.; Roussel, P.; Morrison, G.C.

    1984-01-01

    The ( 14 C, 15 O) complex transfer reaction has been studied at 72 MeV incident energy on 58 Ni, 60 Ni, 62 Ni, 64 Ni, 68 Zn, 70 Zn and 74 Ge, 76 Ge targets. Spectra and differential cross sections have been measured in a 5 0 angular range centred around a laboratory angle of 6 0 . The nucleus 69 Ni has been observed and its mass determined for the first time

  12. Design, synthesis, and evaluation of gadolinium cationic lipids as tools for biodistribution studies of gene delivery complexes.

    Science.gov (United States)

    Leclercq, Francoise; Cohen-Ohana, Mirit; Mignet, Nathalie; Sbarbati, Andrea; Herscovici, Jean; Scherman, Daniel; Byk, Gerardo

    2003-01-01

    Gadolinium-chelating cationic lipids have been synthesized to obtain lipoplexes with MRI contrast properties. These compounds were designed to follow the biodistribution of synthetic DNA for gene delivery by nuclear magnetic resonance imaging. The lipid MCO-I-68 was synthesized, and chelate complexes with gadolinium were formed and characterized in terms of physicochemical and DNA binding properties. The transfection activity of MCO-I-68-Gd/DNA complexes was assayed in vitro on NIH 3T3. Different formulations of the product were tested. When up to 5% of the gadolinium lipid complexes were co-formulated with the cationic lipid RPR120535 used as a reference, the transfection levels were maintained as compared to RPR120535 alone. To date, only a liposomal formulation of a gadolinium-cationic lipid chelate without DNA had been observed using magnetic resonance imaging. In vivo intratumoral administration of MCO-I-68-Gd/DNA lipoplexes to tumor model led to an important increase of the NMR signal. It was demonstrated that the new complexes also acted as transfection carriers when they were formulated from liposomes.

  13. One-dimensional Co(II)/Ni(II) complexes of 2-hydroxyisophthalate: Structures and magnetic properties

    International Nuclear Information System (INIS)

    Wang, Kai; Zou, Hua-Hong; Chen, Zi-Lu; Zhang, Zhong; Sun, Wei-Yin; Liang, Fu-Pei

    2015-01-01

    The solvothermal reactions of 2-hydroxyisophthalic acid (H 3 ipO) with M(NO 3 ) 2 ∙6H 2 O (M=Co, Ni) afforded two complexes [Co 2 (HipO) 2 (Py) 2 (H 2 O) 2 ] (1) and [Ni(HipO)(Py)H 2 O] (2) (Py=pyridine). They exhibit similar zig-zag chain structures with the adjacent two metal centers connected by a anti-syn bridging carboxylate group from the HipO 2− ligand. The magnetic measurements reveal the dominant antiferromagnetic interactions and spin-canting in 1 while ferromagnetic interactions in 2. Both of them exhibit magnetocaloric effect (MCE) with the resulting entropy changes (−ΔS m ) of 12.51 J kg −1 K −1 when ΔH=50 kOe at 3 K for 1 and 11.01 J kg −1 K −1 when ΔH=50 kOe at 3 K for 2, representing the rare examples of one-dimensional complexes with MCE. - Graphical abstract: Synopsis: Two Co(II)/Ni(II) complexes with zig-zag chain structures have been reported. 1-Co shows cant-antiferromagnetism while 2-Ni shows ferromagnetism. Magnetocaloric effect is also found in both of them. - Highlights: • Two one-dimensional Co(II)/Ni(II) complexes were solvothermally synthesized. • The Co-complex exhibits canted antiferromagnetism. • The Ni-complex exhibits ferromagnetism. • Both of the complexes display magnetocaloric effect

  14. Thermodynamic Characteristics of Reactions of the Formation of Complexes between Triglycine and Ni2+ Ions in Aqueous Solution

    Science.gov (United States)

    Gorboletova, G. G.; Metlin, A. A.; Bychkova, S. A.

    2018-05-01

    Thermal effects of reactions of the formation of complexes between Ni(II) and triglycine are determined via direct calorimetry in aqueous solutions at 298.15 K and ionic strengths of 0.2, 0.5, and 1.0 (KNO3). Standard thermodynamic characteristics (Δr H°, Δr G°, Δr S°) of complexing processes in the investigated systems are calculated. The structures of triglycinate complexes NiL+, NiH-1L, NiL2, NiH-2L2- 2, NiL- 3, and NiH-3L4- 3 are introduced to compare the obtained values and data on the thermodynamics of triglycinate complexes of Ni(II).

  15. Cation-π interaction of the univalent sodium cation with [2.2.2]paracyclophane: Experimental and theoretical study

    Science.gov (United States)

    Makrlík, Emanuel; Sýkora, David; Böhm, Stanislav; Vaňura, Petr

    2018-02-01

    By employing electrospray ionization mass spectrometry (ESI-MS), it was proven experimentally that the univalent sodium cation (Na+) forms with [2.2.2]paracyclophane (C24H24) the cationic complex [Na(C24H24)]+. Further, applying quantum chemical DFT calculations, the most probable structure of the [Na(C24H24)]+ complex was derived. In the resulting complex with a symmetry very close to C3, the "central" cation Na+, fully located in the cavity of the parent [2.2.2]paracyclophane ligand, is bound to all three benzene rings of [2.2.2]paracyclophane via cation-π interaction. Finally, the interaction energy, E(int), of the considered cationcomplex [Na(C24H24)]+ was found to be -267.3 kJ/mol, confirming the formation of this fascinating complex species as well.

  16. Studies of a series of [Ni(P(R)2N(Ph)2)2(CH3CN)]2+ complexes as electrocatalysts for H2 production: substituent variation at the phosphorus atom of the P2N2 ligand.

    Science.gov (United States)

    Kilgore, Uriah J; Stewart, Michael P; Helm, Monte L; Dougherty, William G; Kassel, W Scott; DuBois, Mary Rakowski; DuBois, Daniel L; Bullock, R Morris

    2011-11-07

    A series of [Ni(P(R)(2)N(Ph)(2))(2)(CH(3)CN)](BF(4))(2) complexes containing the cyclic diphosphine ligands [P(R)(2)N(Ph)(2) = 1,5-diaza-3,7-diphosphacyclooctane; R = benzyl (Bn), n-butyl (n-Bu), 2-phenylethyl (PE), 2,4,4-trimethylpentyl (TP), and cyclohexyl (Cy)] have been synthesized and characterized. X-ray diffraction studies reveal that the cations of [Ni(P(Bn)(2)N(Ph)(2))(2)(CH(3)CN)](BF(4))(2) and [Ni(P(n-Bu)(2)N(Ph)(2))(2)(CH(3)CN)](BF(4))(2) have distorted trigonal bipyramidal geometries. The Ni(0) complex [Ni(P(Bn)(2)N(Ph)(2))(2)] was also synthesized and characterized by X-ray diffraction studies and shown to have a distorted tetrahedral structure. These complexes, with the exception of [Ni(P(Cy)(2)N(Ph)(2))(2)(CH(3)CN)](BF(4))(2), all exhibit reversible electron transfer processes for both the Ni(II/I) and Ni(I/0) couples and are electrocatalysts for the production of H(2) in acidic acetonitrile solutions. The heterolytic cleavage of H(2) by [Ni(P(R)(2)N(Ph)(2))(2)(CH(3)CN)](BF(4))(2) complexes in the presence of p-anisidine or p-bromoaniline was used to determine the hydride donor abilities of the corresponding [HNi(P(R)(2)N(Ph)(2))(2)](BF(4)) complexes. However, for the catalysts with the most bulky R groups, the turnover frequencies do not parallel the driving force for elimination of H(2), suggesting that steric interactions between the alkyl substituents on phosphorus and the nitrogen atom of the pendant amines play an important role in determining the overall catalytic rate. © 2011 American Chemical Society

  17. In-Situ Immobilization of Ni Complex on Amine-Grafted SiO₂ for Ethylene Polymerization.

    Science.gov (United States)

    Lee, Sang Yun; Ko, Young Soo

    2018-02-01

    The results on the In-Situ synthesis of Ni complex on amine-grafted SiO2 and its ethylene polymerization were explained. SiO2/2NS/(DME)NiBr2 and SiO2/3NS/(DME)NiBr2(Ni(II) bromide ethylene glycol dimethyl ether) catalysts were active for ethylene polymerization. The highest activity was shown at the polymerization temperature of 25 °C, and SiO2/2NS/(DME)NiBr2 exhibited higher activity than SiO2/3NS/(DME)NiBr2. The PDI values of SiO2/2NS/(DME)NiBr2 were in the range of 8~18. The aminosilane compounds and Ni were evenly grafted and distributed in the silica. It was proposed that DME ligand was mostly removed during the supporting process, and only NiBr2 was complexed with the amine group of 2NS based on the results of FT-IR and ethylene polymerization.

  18. Complexation of the cesium cation with lithium ionophore VIII: extraction and DFT study

    Czech Academy of Sciences Publication Activity Database

    Makrlík, E.; Novák, Vít; Vaňura, P.; Bouř, Petr

    2013-01-01

    Roč. 298, č. 3 (2013), s. 2065-2068 ISSN 0236-5731 Institutional support: RVO:61388963 Keywords : cesium cation * lithium ionophore VIII * complexation * extraction and stability constants * water-nitrobenzene system * DFT calculations * structures Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 1.415, year: 2013

  19. Complexation as an approach to entrap cationic drugs into cationic nanoparticles administered intranasally for Alzheimer's disease management: preparation and detection in rat brain.

    Science.gov (United States)

    Hanafy, Amira S; Farid, Ragwa M; ElGamal, Safaa S

    2015-01-01

    Complexation was investigated as an approach to enhance the entrapment of the cationic neurotherapeutic drug, galantamine hydrobromide (GH) into cationic chitosan nanoparticles (CS-NPs) for Alzheimer's disease management intranasally. Biodegradable CS-NPs were selected due to their low production cost and simple preparation. The effects of complexation on CS-NPs physicochemical properties and uptake in rat brain were examined. Placebo CS-NPs were prepared by ionic gelation, and the parameters affecting their physicochemical properties were screened. The complex formed between GH and chitosan was detected by the FT-IR study. GH/chitosan complex nanoparticles (GH-CX-NPs) were prepared by ionic gelation, and characterized in terms of particle size, zeta potential, entrapment efficiency, in vitro release and stability for 4 and 25 °C for 3 months. Both placebo CS-NPs and GH-CX-NPs were visualized by transmission electron microscopy. Rhodamine-labeled GH-CX-NPs were prepared, administered to male Wistar rats intranasally, and their delivery to different brain regions was detected 1 h after administration using fluorescence microscopy and software-aided image processing. Optimized placebo CS-NPs and GH-CX-NPs had a diameter 182 and 190 nm, and a zeta potential of +40.4 and +31.6 mV, respectively. GH encapsulation efficiency and loading capacity were 23.34 and 9.86%, respectively. GH/chitosan complexation prolonged GH release (58.07% ± 6.67 after 72 h), improved formulation stability at 4 °C in terms of drug leakage and particle size, and showed insignificant effects on the physicochemical properties of the optimized placebo CS-NPs (p > 0.05). Rhodamine-labeled GH-CX-NPs were detected in the olfactory bulb, hippocampus, orbitofrontal and parietal cortices. Complexation is a promising approach to enhance the entrapment of cationic GH into the CS-NPs. It has insignificant effect on the physicochemical properties of CS-NPs. GH-CX-NPs were successfully

  20. Cationic bis-N-heterocyclic carbene (NHC) ruthenium complex: Structure and application as latent catalyst in olefin metathesis

    KAUST Repository

    Rouen, Mathieu

    2014-09-11

    An unexpected cationic bis-N-heterocyclic carbene (NHC) benzylidene ether based ruthenium complex (2 a) was prepared through the double incorporation of an unsymmetrical unsaturated N-heterocyclic carbene (U2-NHC) ligand that bore an N-substituted cyclododecyl side chain. The isolation and full characterization (including X-ray diffraction studies) of key synthetic intermediates along with theoretical calculations allowed us to understand the mechanism of the overall cationization process. Finally, the newly developed complex 2 a displayed interesting latent behavior during ring-closing metathesis, which could be "switched on" under acidic conditions.

  1. Structural, vibrational and morphological properties of layered double hydroxides containing Ni{sup 2+}, Zn{sup 2+}, Al{sup 3+} and Zr{sup 4+} cations

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, Débora M. [Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, CEP 13566-590 São Carlos, SP (Brazil); Rodrigues, João E.F.S. [Instituto de Física de São Carlos, Universidade de São Paulo, CP 780, CEP 13560-970 São Carlos, SP (Brazil); Assaf, Elisabete M., E-mail: eassaf@iqsc.usp.br [Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, CEP 13566-590 São Carlos, SP (Brazil)

    2017-03-15

    Layered double hydroxides are anionic clays with formula [M{sup II}{sub 1−x} M{sup III}{sub x}(OH){sub 2}]{sup q+}[A{sup n−}]{sub q/n}·mH{sub 2}O, finding possible uses as catalyst support, adsorbents and so on. In this paper, we address the phase formation of layered double hydroxides containing Ni{sup 2+}, Zn{sup 2+}, Al{sup 3+} and Zr{sup 4+} cations, namely, NiZn-Al, NiZn-AlZr and NiZn-Zr compositions obtained by the coprecipitation method. Such systems were characterized by X-ray diffraction, confirming the phase formation for NiZn-Al and NiZn-AlZr samples. Infrared and Raman spectroscopies elucidated the anion and water molecules occurrence in the interlayer. Nitrogen physisorption (BET method) determined the presence of pores and specific surface area. The isotherm shapes were Type IV, according to the IUPAC, and represent a mesoporous structure. A morphological study was performed by means of scanning and transmission electron microscopies, and particle size values of 120, 131 and 235 nm for NiZn-Al, NiZn-AlZr and NiZn-Zr, respectively, were determined. Thermogravimetric analysis of the decomposition of the systems revealed that their complete disintegration occurred at ~ 450 °C and resulted in mixed oxides.

  2. Environmental Remediation and Sorption of Metal Cations Using Aluminum Pillared Nano-Bentonite

    Science.gov (United States)

    Rifai, Rifai; Abou El Safa, Magda

    2015-04-01

    The release of heavy metal cations into the environment is a potential threat to water and soil quality. Some clay minerals play an important role, as physical and chemical barriers, for the isolation of metal-rich wastes and to adsorb heavy metals as well as to avoid their environmental dispersion. In the present study, the bentonitic clay (southeast El-Hammam City, Egypt) was subjected to pillaring using hydroxyl-aluminum solution. The XRD patterns of the Aluminum Pillared Nano-Bentonite (APNB) showed severe alteration of the crystal structure after pillaring. Poly metal solutions with different metal concentrations of Cu, Co, Ni, Zn, Cd and Pb (0.001, 0.005 and 0.01 moles), and pH (1, 2.5, 5 and 6) were subjected to treatment by the APNB. The removal process is very rapid and spontaneous and the contact time may be short (several minutes) for most adsorption to occur. The criterion for environmental remediation of APNB is less stringent and a short contact time is sufficient. The rate of Cu2+, Zn2+, Co2+, Cd2+, Ni2+ and Pb2+sorption remained higher or equal to the CEC. The sorption of metal ions by APNB are complex and probably involve several mechanisms. In general, APNB can be used to immobilize Cu2+, Zn2+, Co2+, Cd2+, Ni2+ and Pb2+ to any extent. For each metal ion, the most effective immobilization occurs over a particular pH around 5. According to the experimental data obtained, the uptake amount of the studied cations by APNB increased with increasing solution pH, sorbent dose and contact time. The preference of the APNB adsorption for heavy metal ions that are through the cation exchange processes decreases in the order: Cu2+>Zn2+>Co2+>Cd2+ >Ni2+ >Pb2+. Keywords: Bentonitic clay, Egypt, Aluminum Pillared Nano-Bentonite, heavy metal, environmental remediation

  3. Quantum mechanics and molecular dynamics simulations of complexation of alkaline-earth and lanthanide cations by poly-amino-carboxylate ligands; Simulations par mecanique quantique et dynamique moleculaire de la complexation de cations alcalino-terreux et lanthanides par des ligands polyaminocarboxylates

    Energy Technology Data Exchange (ETDEWEB)

    Durand, S

    1999-07-01

    Molecular dynamics (MD) simulations on lanthanide(III) and alkaline-earth(II) complexes with poly-amino-carboxylates (ethylene-diamino-tetra-acetate EDTA{sup 4-}, ethylene-diamino-tri-acetate-acetic acid EDTA(H){sup 3-}, tetra-aza-cyclo-dodecane-tetra-acetate DOTA{sup 4-}, methylene-imidine-acetate MIDA{sup 2-}) are reported. First, a consistent set of Lennard-Jones parameters for La{sup 3+}, Eu{sup 3+} and Lu{sup 3+} cations has been derived from free energy calculations in aqueous solution. Observed differences in hydration free energies, coordination distances and hydration numbers are reproduced. Then, the solution structures of 1:1 complexes of alkaline-earth and/or lanthanide cations with EDTA{sup 4-}, EDTA(H){sup 3-}, DOTA{sup 4-} and 1:2 complexes of lanthanide cations with MIDA{sup 2-} were studied by MD in water. In addition, free energy calculations were performed to study, for each ligand, the relative thermodynamic stabilities of complexes with Ca{sup 2+} vs Sr{sup 2+} and vs Ba{sup 2+} on the one hand, and with La{sup 3+} vs Eu{sup 3+} and vs Lu{sup 3+} on the other hand. Model does not take into account explicitly polarization and charge transfer. However, the results qualitatively agree with experimental complexation data (structure and selectivities). (author)

  4. Heterobimetallic [NiFe] Complexes Containing Mixed CO/CN- Ligands: Analogs of the Active Site of the [NiFe] Hydrogenases.

    Science.gov (United States)

    Perotto, Carlo U; Sodipo, Charlene L; Jones, Graham J; Tidey, Jeremiah P; Blake, Alexander J; Lewis, William; Davies, E Stephen; McMaster, Jonathan; Schröder, Martin

    2018-03-05

    The development of synthetic analogs of the active sites of [NiFe] hydrogenases remains challenging, and, in spite of the number of complexes featuring a [NiFe] center, those featuring CO and CN - ligands at the Fe center are under-represented. We report herein the synthesis of three bimetallic [NiFe] complexes [Ni( N 2 S 2 )Fe(CO) 2 (CN) 2 ], [Ni( S 4 )Fe(CO) 2 (CN) 2 ], and [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] that each contain a Ni center that bridges through two thiolato S donors to a {Fe(CO) 2 (CN) 2 } unit. X-ray crystallographic studies on [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ], supported by DFT calculations, are consistent with a solid-state structure containing distinct molecules in the singlet ( S = 0) and triplet ( S = 1) states. Each cluster exhibits irreversible reduction processes between -1.45 and -1.67 V vs Fc + /Fc and [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] possesses a reversible oxidation process at 0.17 V vs Fc + /Fc. Spectroelectrochemical infrared (IR) and electron paramagnetic resonance (EPR) studies, supported by density functional theory (DFT) calculations, are consistent with a Ni III Fe II formulation for [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + . The singly occupied molecular orbital (SOMO) in [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + is based on Ni 3d z 2 and 3p S with the S contributions deriving principally from the apical S-donor. The nature of the SOMO corresponds to that proposed for the Ni-C state of the [NiFe] hydrogenases for which a Ni III Fe II formulation has also been proposed. A comparison of the experimental structures, and the electrochemical and spectroscopic properties of [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] and its [Ni( N 2 S 3 )] precursor, together with calculations on the oxidized [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + and [Ni( N 2 S 3 )] + forms suggests that the binding of the {Fe(CO)(CN) 2 } unit to the {Ni(CysS) 4 } center at the active site of the [NiFe] hydrogenases suppresses thiolate-based oxidative chemistry involving the bridging thiolate S donors

  5. Spin crossover studies in cationic complexes of iron by using Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Vadera, S.R.; Kumar, N.

    1990-01-01

    The spin transition in two new cationic complexes of iron, i.e. iron bipyridine formate, [Fe(bipy) 3 ](HCOO) 2 .5(HCOOH) and iron bipyridine tetrafluoro borate, [Fe(bipy) 3 ](BF 4 ) 2 .2H 2 O were studied by Moessbauer spectroscopy. From quadrupole splitting values, it was established that at different temperatures both complexes show the coexistence of both high spin state and low spin state at 300 K, while complete transformation to low spin state occurs at 77 K. Both compounds were prepared by electrochemical technique. (author) 12 refs.; 1 fig.; 1 tab

  6. Complexing properties of some carbamoylmethylphosphine oxides and methylenediphosphine dioxides with respect to alkali metal cations and the effect of abnormal aryl strengthening

    International Nuclear Information System (INIS)

    Evreinov, V.I.; Safronova, Z.V.; Yarkevich, A.N.; Kharitonov, A.V.; Bondarenko, N.A.; Tsvetkov, E.N.

    1999-01-01

    By the method of conductometry in anhydrous tetrahydrofuran at 25 Deg C stability constants of alkali metal (M = Li, Na, K) cation complexes with certain phosphinoxides have been determined. Abnormal aryl strengthening is first of all pronounced in the cation complexes with tetraphenyldiphosphine dioxide [ru

  7. Accelerators for forming cationic technetium complexes useful as radiodiagnostic images

    International Nuclear Information System (INIS)

    Tweedle, M.F.

    1985-01-01

    This invention relates to compositions for making cationic radiodiagnostic agents and, in particular, to accelerator compounds for labelling such cationic radiodiagnostic agents, kits for preparing such 99m Tc-labelled cationic radiodiagnostic agents with technetium, and methods for labelling such cationic radiodiagnostic agents with technetium

  8. Structural characterization and antioxidant properties of Cu(II) and Ni(II) complexes derived from dicyandiamide

    Science.gov (United States)

    Kertmen, Seda Nur; Gonul, Ilyas; Kose, Muhammet

    2018-01-01

    New Cu(II) and Ni(II) complexes derived from dicyandiamide were synthesized and characterised by spectroscopic and analytical methods. Molecular structures of the complexes were determined by single crystal X-ray diffraction studies. In the complexes, the Cu(II) or Ni(II) ions are four-coordinate with a slight distorted square planar geometry. The ligands (L-nPen and L-iPen) derived from dicyandiamide formed via nucleophilic addition of alcohol solvent molecule in the presence Cu(II) or Ni(II) ions. Complexes were stabilised by intricate array of hydrogen bonding interactions. Antioxidant activity of the complexes was evaluated by DPPH radical scavenging and CUPRAC methods. The complexes exhibit antioxidant activity, however, their activities were much lower than standard antioxidants (Vitamin C and trolox).

  9. Theoretical study of the magnetic behavior of hexanuclear Cu(II) and Ni(II) polysiloxanolato complexes.

    Science.gov (United States)

    Ruiz, Eliseo; Cano, Joan; Alvarez, Santiago; Caneschi, Andrea; Gatteschi, Dante

    2003-06-04

    A theoretical density functional study of the exchange coupling in hexanuclear polysiloxanolato-bridged complexes of Cu(II) and Ni(II) is presented. By calculating the energies of three different spin configurations, we can obtain estimates of the first-, second-, and third-neighbor exchange coupling constants. The study has been carried out for the complete structures of the Cu pristine cluster and of the chloroenclathrated Ni complex as well as for the hypotethical pristine Ni compound and for magnetically dinuclear analogues M(2)Zn(4) (M = Cu, Ni).

  10. The thermodynamic stability of hydrogen bonded and cation bridged complexes of humic acid models-A theoretical study

    International Nuclear Information System (INIS)

    Aquino, Adelia J.A.; Tunega, Daniel; Pasalic, Hasan; Haberhauer, Georg; Gerzabek, Martin H.; Lischka, Hans

    2008-01-01

    Hydrogen bonded and cation bridged complexation of poly(acrylic acid) oligomers, representing a model compound for humic acids, with acetic acid and the herbicide (4-chloro-2-methylphenoxy) acetic acid (MCPA) have been studied by means of density functional theory. Solvation effects were computed by means of a combination of microsolvation (explicit insertion of water molecules) and global solvation (polarizable continuum approach). The stability of hydrogen bonded complexes in solution is characterized by a strong competition between solute and solvent molecules. The cation bridged complexes of the negatively charged (deprotonated) ligands were found to be strongly favored explaining the capability of humic acids to fixate anionic species from soil solutions and the ability to form cross-linking structures within the humic acid macromolecules

  11. Characterization of La2MoO6 prepared by the cation complexation technique

    International Nuclear Information System (INIS)

    Rocha, R.A.; Muccillo, E.N.S.

    2005-01-01

    The La 2 MoO 6 mixed oxide was prepared by the cation complexation technique using citric acid as complexant agent. The main purpose of this work was to obtain a mesoporous powder with relatively high specific surface area. The thermal decomposition behavior of the metal complex was studied by thermal analysis and Fourier transform infrared spectroscopy. A specific surface area value of ∼15 m 2 g -1 was obtained by nitrogen adsorption/desorption measurements. X-ray diffraction patterns of calcined mesoporous materials reveal that even though a low degree of crystallinity is attained, this phase may be obtained at low temperatures

  12. Extraction and theoretical study on the complexation of the strontium cation with beauvericin

    Czech Academy of Sciences Publication Activity Database

    Makrlík, E.; Toman, Petr; Vaňura, P.

    2013-01-01

    Roč. 295, č. 2 (2013), s. 1119-1122 ISSN 0236-5731 R&D Projects: GA ČR(CZ) GAP205/10/2280 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : strontium cation * beauvericin * complexation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.415, year: 2013

  13. Quantum mechanics and molecular dynamics simulations of complexation of alkaline-earth and lanthanide cations by poly-amino-carboxylate ligands

    International Nuclear Information System (INIS)

    Durand, S.

    1999-01-01

    Molecular dynamics (MD) simulations on lanthanide(III) and alkaline-earth(II) complexes with poly-amino-carboxylates (ethylene-diamino-tetra-acetate EDTA 4- , ethylene-diamino-tri-acetate-acetic acid EDTA(H) 3- , tetra-aza-cyclo-dodecane-tetra-acetate DOTA 4- , methylene-imidine-acetate MIDA 2- ) are reported. First, a consistent set of Lennard-Jones parameters for La 3+ , Eu 3+ and Lu 3+ cations has been derived from free energy calculations in aqueous solution. Observed differences in hydration free energies, coordination distances and hydration numbers are reproduced. Then, the solution structures of 1:1 complexes of alkaline-earth and/or lanthanide cations with EDTA 4- , EDTA(H) 3- , DOTA 4- and 1:2 complexes of lanthanide cations with MIDA 2- were studied by MD in water. In addition, free energy calculations were performed to study, for each ligand, the relative thermodynamic stabilities of complexes with Ca 2+ vs Sr 2+ and vs Ba 2+ on the one hand, and with La 3+ vs Eu 3+ and vs Lu 3+ on the other hand. Model does not take into account explicitly polarization and charge transfer. However, the results qualitatively agree with experimental complexation data (structure and selectivities). (author)

  14. Design and synthesis of quasi-diastereomeric molecules with unchanging central, regenerating axial and switchable helical chirality via cleavage and formation of Ni(II–O and Ni(II–N coordination bonds

    Directory of Open Access Journals (Sweden)

    Vadim A. Soloshonok

    2012-11-01

    Full Text Available We describe herein the design and synthesis of asymmetric, pentadentate ligands, which are able to coordinate to Ni(II cations leading to quasi-diastereomeric complexes displaying two new elements of chirality: stereogenic axis and helix along with configurational stabilization of the stereogenic center on the nitrogen. Due to the stereocongested structural characteristics of the corresponding Ni(II complexes, the formation of quasi-diastereomeric products is highly stereoselective providing formation of only two, (Ra*,Mh*,Rc* and (Ra*,Ph*,Rc*, out of the four possible stereochemical combinations. The reversible quasi-diastereomeric transformation between the products (Ra*,Mh*,Rc* and (Ra*,Ph*,Rc* occurs by intramolecular trans-coordination of Ni–NH and Ni–O bonds providing a basis for a chiral switch model.

  15. Family of defect-dicubane Ni4Ln2 (Ln = Gd, Tb, Dy, Ho) and Ni4Y2 complexes: rare Tb(III) and Ho(III) examples showing SMM behavior.

    Science.gov (United States)

    Zhao, Lang; Wu, Jianfeng; Ke, Hongshan; Tang, Jinkui

    2014-04-07

    Reactions of Ln(III) perchlorate (Ln = Gd, Tb, Dy, and Ho), NiCl2·6H2O, and a polydentate Schiff base resulted in the assembly of novel isostructural hexanuclear Ni4Ln2 complexes [Ln = Gd (1), Tb (2), Dy (3), Ho (4)] with an unprecedented 3d-4f metal topology consisting of two defect-dicubane units. The corresponding Ni4Y2 (5) complex containing diamagnetic Y(III) atoms was also isolated to assist the magnetic studies. Interestingly, complexes 2 and 3 exhibit SMM characteristics and 4 shows slow relaxation of the magnetization. The absence of frequency-dependent in-phase and out-of-phase signals for the Ni-Y species suggests that the Ln ions' contribution to the slow relaxation must be effectual as previously observed in other Ni-Dy samples. However, the observation of χ″ signals with zero dc field for the Ni-Tb and Ni-Ho derivatives is notable. Indeed, this is the first time that such a behavior is observed in the Ni-Tb and Ni-Ho complexes.

  16. The study of new complex compounds of Ni (II) and Co (II) with N- hydroxy-succinimide and their potential applications as sensors

    Science.gov (United States)

    Sibiescu, Doina; Tutulea, Mihaela-Dana; Mîţă, Carmen; Stan, Corneliu; Roţca, Ioan; Vizitiu, Mihaela

    2010-11-01

    In this paper, the study of obtaining new coordination compounds of Ni (II) and Co(II) using as ligand, N-hydroxy-succinimide, was presented. Also, the stability constants of these compounds in aqueous medium were determined. The obtaining conditions and the stability of the new compounds were accomplished in aqueous solutions using characteristic methods for coordination compounds: pH-metry, conductometry and UV-VIS absorption spectroscopy. The combination ratios and the stability constants were determined with methods characteristic for studies in solutions. From experimental data resulted that the combination ratio of central metallic atoms with the ligand N-hydroxy-succinimide was: 1:1 and respectively 1:2. In the experiments were used salts of NiCl2.6H2O and CoCl2.6H2O. The optimal domain of pH stability of the studied compounds is limited between 5.74 - 5.86 for Co- N-hydroxy-succinimide (for molar ratio 1:1 and 1:2) and respectively 5.69 - 5.87 for Ni-N-hydroxysuccinimide( for molar ratio 1:1 and 1:2, too). It is important to mention that these compounds were used with very good results in determination of wastewaters from textile, metallurgical, chemical and food industry. Complexion reactions with this ligand are very sensitive for the cations in this paper mentioned. Therefore it is used most often with success in analytical chemistry and also it is posibil to use as sensors. The new complex compounds has electronics transitions at λ = 517 nm for both complexes Co-N-hydroxy-succinimide at molar ratio 1:1 and 1:2 and also at the same λ = 397nm for Ni-N-hydroxysuccinimide at molar ratio 1:1 and 1:2. These complexes compounds was separated and recrystallized from aqueous solution. From the spectrophotometric data it was determined the type and the nature of the electronics transitions by Dq parameters.

  17. Effects of Nanoscale Carbon Black Modified by HNO3 on Immobilization and Phytoavailability of Ni in Contaminated Soil

    Directory of Open Access Journals (Sweden)

    Jiemin Cheng

    2015-01-01

    Full Text Available A surface-modified nanoscale carbon black (MCB as Ni adsorbent in contaminated soil was prepared by oxidizing the carbon black with 65% HNO3. The surface properties of the adsorbent were characterized by zeta potential analysis, scanning electron microscopy (SEM, and Fourier transform infrared spectroscopy (FTIRs. Batch experiments were conducted to evaluate the improvement of Ni2+ adsorption by MCB. Greenhouse cultivation experiments were conducted to examine the effect of MCB on the DTPA-extractable Ni2+ in soil, Ni2+ uptake of ryegrass shoot, and growth of ryegrass. Results indicated that MCB had much lower negative zeta potential, more functional groups for exchange and complexation of cation, and more heterogeneous pores and cavities for the adsorption of cation than the unmodified parent one (CB. MCB showed enhanced sorption capacity for Ni (qmax, 49.02 mg·g−1 compared with CB (qmax, 39.22 mg·g−1. Greenhouse cultivation experiment results showed that the biomass of ryegrass shoot and the Ni uptake of the ryegrass shoot were significantly increased and the concentrations of DTPA-extractable Ni in soil were significantly decreased with the increasing of MCB amount. It is clear from this work that the MCB had good adsorption properties for the Ni and could be applied in the in situ immobilization and remediation of heavy metal contaminated saline-alkali soils.

  18. Hydration of cations: a key to understanding of specific cation effects on aggregation behaviors of PEO-PPO-PEO triblock copolymers.

    Science.gov (United States)

    Lutter, Jacob C; Wu, Tsung-yu; Zhang, Yanjie

    2013-09-05

    This work reports results from the interactions of a series of monovalent and divalent cations with a triblock copolymer, poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO). Phase transition temperatures of the polymer in the presence of chloride salts with six monovalent and eight divalent cations were measured using an automated melting point apparatus. The polymer undergoes a two-step phase transition, consisting of micellization of the polymer followed by aggregation of the micelles, in the presence of all the salts studied herein. The results suggest that hydration of cations plays a key role in determining the interactions between the cations and the polymer. The modulation of the phase transition temperature of the polymer by cations can be explained as a balance between three interactions: direct binding of cations to the oxygen in the polymer chains, cations sharing one water molecule with the polymer in their hydration layer, and cations interacting with the polymer via two water molecules. Monovalent cations Na(+), K(+), Rb(+), and Cs(+) do not bind to the polymer, while Li(+) and NH4(+) and all the divalent cations investigated including Mg(2+), Ca(2+), Sr(2+), Ba(2+), Co(2+), Ni(2+), Cu(2+), and Cd(2+) bind to the polymer. The effects of the cations correlate well with their hydration thermodynamic properties. Mechanisms for cation-polymer interactions are discussed.

  19. The role of microorganisms in the mobility of radionuclides in soil II. Evaluation of siderophone-cation complex forming capacity

    International Nuclear Information System (INIS)

    Konyi, J.; Koska, P.; Berzsenyi, G.; Gazso, L.G.; Appanna, V.D.

    1997-01-01

    Siderophores are cation binding agents produced by microorganisms. They are specific for Fe(III) but may bind other cations, too. Gram positive bacteria, Gram negative bacteria, filamentous bacteria and fungi isolated from soil samples were examined for siderophore production using chrome-asurol agar plates. We found that 44.5% of the isolates are able to produce siderophores. Spectral analysis of the produced exudates shoved cobalt and zinc binding capacity. Adding of a strong complexing agent (EDDHA) does not influence the stability of the formed metal-complex. (authors)

  20. Effect of second-sphere cation nature on the character of IR spectra of molybdeum(4, 5) cyanide complexes

    International Nuclear Information System (INIS)

    Zubritskaya, D.I.; Semenishin, D.I.; Vretsena, N.B.; Chernyak, B.I.

    1989-01-01

    The effect of nature of second-sphere cations on IR spectra of molybdeum (4, 5) cyanide complexes is studied. It is found that the increase in the first ionization potential (radius decrease) brings about the increase in the frequency of valent variations ν (CN). This proves the possibility of formation of bridge bonds Mo-CN-M in the compounds (M-alkali, alkaline earth or rare earth metal, Cs, Y). The conclusion is made on a considerable effect of the nature of second-sphere cations and oxidation degree of complexing agent atoms on the nature of IR spectra of octacyanomolybdates (4, 5)

  1. Antimony(3) ethylenediaminetetraacetate complexes with single- and doubly charged cations

    International Nuclear Information System (INIS)

    Davidovich, R.L.; Logvinova, V.B.; Kajdalova, T.A.

    1998-01-01

    The antimony(3) ethylenediaminetetraacetate complexes with alkaline and bivalent metals cations of the M + Sb(Edta) · H 2 O (M + = K, Rb, Cs, NH 4 ), M 2+ [Sb(Edta)] 2 · 8H 2 O (M 2+ = Mg, Ca, Sr, Co, Cd) composition are synthesized. Roentgenographic and IR-spectroscopic characteristics of the synthesized substances are determined. Two groups of the isostructural compounds: M + Sb(Edta) · H 2 O (M + = K, Rb, NH 4 ) and M 2+ [Sb(Edta)] 2 · 8H 2 O (M 2+ = Mg, Ca, Sr, Mn, Co, Cd) are established [ru

  2. Heterospin systems constructed from [Cu2Ln]3+ and [Ni(mnt)2]1-,2- Tectons: First 3p-3d-4f complexes (mnt = maleonitriledithiolato).

    Science.gov (United States)

    Madalan, Augustin M; Avarvari, Narcis; Fourmigué, Marc; Clérac, Rodolphe; Chibotaru, Liviu F; Clima, Sergiu; Andruh, Marius

    2008-02-04

    New heterospin complexes have been obtained by combining the binuclear complexes [{Cu(H(2)O)L(1)}Ln(O(2)NO)(3)] or [{CuL(2)}Ln(O(2)NO)(3)] (L(1) = N,N'-propylene-di(3-methoxysalicylideneiminato); L(2) = N,N'-ethylene-di(3-methoxysalicylideneiminato); Ln = Gd(3+), Sm(3+), Tb(3+)), with the mononuclear [CuL(1)(2)] and the nickel dithiolene complexes [Ni(mnt)(2)](q)- (q = 1, 2; mnt = maleonitriledithiolate), as follows: (1)infinity[{CuL(1)}(2)Ln(O(2)NO){Ni(mnt)(2)}].Solv.CH(3)CN (Ln = Gd(3+), Solv = CH(3)OH (1), Ln = Sm(3+), Solv = CH(3)CN (2)) and [{(CH(3)OH)CuL(2)}(2)Sm(O(2)NO)][Ni(mnt)(2)] (3) with [Ni(mnt)2]2-, [{(CH(3)CN)CuL(1)}(2)Ln(H(2)O)][Ni(mnt)(2)]3.2CH(3)CN (Ln = Gd(3+) (4), Sm(3+) (5), Tb(3+) (6)), and [{(CH(3)OH)CuL(2)}{CuL(2)}Gd(O(2)NO){Ni(mnt)(2)}][Ni(mnt)(2)].CH(2)Cl(2) (7) with [Ni(mnt))(2]*-. Trinuclear, almost linear, [CuLnCu] motifs are found in all the compounds. In the isostructural 1 and 2, two trans cyano groups from a [Ni(mnt)2]2- unit bridge two trimetallic nodes through axial coordination to the Cu centers, thus leading to the establishment of infinite chains. 3 is an ionic compound, containing discrete [{(CH(3)OH)CuL(2)}(2)Sm(O(2)NO)](2+) cations and [Ni(mnt)(2)](2-) anions. Within the series 4-6, layers of discrete [CuLnCu](3+) motifs alternate with stacks of interacting [Ni(mnt)(2)](*-) radical anions, for which two overlap modes, providing two different types of stacks, can be disclosed. The strength of the intermolecular interactions between the open-shell species is estimated through extended Hückel calculations. In compound 7, [Ni(mnt)(2)](*-) radical anions coordinate group one of the Cu centers of a trinuclear [Cu(2)Gd] motif through a CN, while discrete [Ni(mnt)(2)](*-) units are also present, overlapping in between, but also with the coordinated ones. Furthermore, the [Cu(2)Gd] moieties dimerize each other upon linkage by two nitrato groups, both acting as chelate toward the gadolinium ion from one unit and monodentate toward a

  3. Predicting the uptake of Cs, Co, Ni, Eu, Th and U on argillaceous rocks using sorption models for illite

    International Nuclear Information System (INIS)

    Marques Fernandes, Maria; Vér, Nóra; Baeyens, Bart

    2015-01-01

    Highlights: • Contaminant retention in argillaceous rocks controlled by sorption on clay minerals. • Cs, Ni, Co, Eu, Th and UO 2 sorption isotherm measurements on Boda and Opalinus Clay. • Boda and Opalinus Clay exhibit different mineralogies and porewater compositions. • Blind predictions using quasi-mechanistic sorption models developed for illite. • Good agreement between measurements and blind predictions. - Abstract: Reliable predictions of radiocontaminant migration are a requirement for the establishment of radioactive waste repositories. Parametrization of the necessary sorption models seems to be, however, extremely challenging given the multi-mineralic composition of the lithosphere. In this study it is shown for two argillaceous rocks – Boda and Opalinus Clay relevant for the Hungarian and Swiss repository concepts, respectively – that this task can be substantially simplified by taking into account only the most sorptive mineral fraction, namely the 2:1 clay minerals illite and illite/smectite mixed layers. Two different models were required to blind predict the sorption isotherms of Cs, Co, Ni, Eu, Th and UO 2 measured on the two clay rock samples in a synthetic porewater. Cs sorption was modelled with the generalised Cs (GCs) sorption model and the sorption of the other cations with the 2site protolysis non electrostatic surface complexation and cation exchange (2SPNE SC/CE) model. The 2SPNE SC/CE model for illite was extended with surface complexation reactions on weak sites for Co, Ni, Eu, UO 2 and on strong sites for Eu-carbonato complexes. Complementary to the sorption measurements and modelling, extended X-ray absorption fine structure (EXAFS) spectroscopy was used to probe the retention mechanism of Ni on illite, Boda and Opalinus Clay at higher loadings. The reliable blind predictions of the selected metal cations, which are representative for monovalent alkaline metals, divalent transition metals, lanthanides, and trivalent

  4. Aza-crown ether complex cation ionic liquids: preparation and applications in organic reactions.

    Science.gov (United States)

    Song, Yingying; Cheng, Chen; Jing, Huanwang

    2014-09-26

    Aza-crown ether complex cation ionic liquids (aCECILs) were devised, fabricated, and characterized by using NMR spectroscopy, MS, thermogravimetric differential thermal analysis (TG-DTA), elemental analysis and physical properties. These new and room-temperature ILs were utilized as catalysts in various organic reactions, such as the cycloaddition reaction of CO2 to epoxides, esterification of acetic acid and alcohols, the condensation reaction of aniline and propylene carbonate, and Friedel-Crafts alkylation of indole with aldehydes were investigated carefully. In these reactions, the ionic liquid exhibited cooperative catalytic activity between the anion and cation. In addition, the aza-[18-C-6HK][HSO4]2 was the best acidic catalyst in the reactions of esterification and Friedel-Crafts alkylation under mild reaction conditions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. The Chemical States of Color-Induced Cations in Tourmaline Characterized by X-Ray Photoelectron Spectroscopy

    Directory of Open Access Journals (Sweden)

    Ming Li

    2018-01-01

    Full Text Available In order to better understand the effect of transition metal cations on color of tourmaline, X-ray photoelectron spectroscopy was used to investigate the species, chemical state, site occupancy, and chemical environment of color-induced metal cations in colorful tourmaline samples from Minas Gerais State, Brazil. Our results showed that the colorful tourmalines usually contained a small amount of transition metal elements, and a colorful tourmaline sample had several transition metal cations; however, the color of tourmaline resulted from the transition metal cations in the Y site of the crystal structure. The pink color of tourmaline was associated with Mn2+ in the Y site coordinating with F; the yellow color was derived from Ni2+ in the Y site binding to O; the green color was associated with Fe3+ in the Y site coordinating with O, OH, and F; the rose red color originated from Mn2+ and Ni2+ in the Y site in which Mn2+ coordinated with O and F, and Ni2+ coordinated with O; and the blue color was derived from Fe3+ and Mn2+ in the Y site in which Fe3+ binded to O, OH, and F and Mn2+ binded to F. Additionally, other transition metal cations were also observed in colorful tourmalines, but all these species occupied the Z site of the structure. In the pink and yellow samples, Fe and Cr were observed in Fe3+ and Cr3+; in the rose red sample, Fe was also found in Fe3+; in the blue sample, Cr was present in Cr3+; in the green sample, Mn, Ni, and Cu were found in Mn2+, Ni2+, and Cu2+, respectively. The color of tourmaline was induced from the absorption of the d-d transition of transition metals in the crystal structure, as charge transfer tended to occur between cations occupying different coordination positions.

  6. Revisiting caffeate's capabilities as a complexation agent to silver cation in mining processes by means of the dual descriptor--a conceptual DFT approach.

    Science.gov (United States)

    Martínez-Araya, Jorge Ignacio

    2012-09-01

    Caffeic acid (C(9)H(8)O(4)) and its conjugate base C(9)H(7)O(4) (-) (anionic form-known as caffeate) were analyzed computationally through the use of quantum chemistry to assess their intrinsic global and local reactivity using the tools of conceptual density functional theory. The anionic form was found to be better at coordinating the silver cation than caffeic acid thus suggesting the use of caffeate as a complexation agent. The complexation capability of caffeate was compared with that of some of the most common ligand agents used to coordinate silver cations. Local reactivity descriptors allowed identification of the preferred sites on caffeate for silver cation coordination thus generating a plausible silver complex. All silver complexes were analyzed thermodynamically considering interaction energies in both gas and aqueous phases; the complexation free energy in aqueous phase was also determined. These results suggest that more attention be paid to the caffeate anion and its derivatives because this work has shed new light on the behavior of this anion in the recovery of silver cations that could be exploited in silver mining processes in a environmentally friendly way.

  7. Remarkable fluorescence enhancement versus complex formation of cationic porphyrins on the surface of ZnO nanoparticles

    KAUST Repository

    Aly, Shawkat Mohammede; Eita, Mohamed Samir; Khan, Jafar Iqbal; Alarousu, Erkki; Mohammed, Omar F.

    2014-01-01

    the first experimental measurements demonstrating a clear transition from pronounced fluorescence enhancement to charge transfer (CT) complex formation by simply changing the nature and location of the positive charge of the meso substituent of the cationic

  8. Syntheses, crystal structures and Hirshfeld surface analysis of a coordination polymer of Cu(II) chlorido and a tris-octahedral complex of Ni(II) containing isonicotinoylhydrazone blockers

    Science.gov (United States)

    Mahmoudi, Ghodrat; Chowdhury, Habibar; Ghosh, Barindra K.; Lofland, Samuel E.; Maniukiewicz, Waldemar

    2018-05-01

    One-pot reactions of pre-assigned molar ratios of appropriate metal (II) salts and HL1 (2-acetylpyridine nicotinoylhydrazone) or HL2 (2-acetylpyridine isonicotinoylhydrazone) in MeOH solutions at room temperature afford 1D coordination polymeric chain [Cu(μ-L1) (Cl)]n (1) and a mononuclear complex [Ni(L2)2] (2). The compounds (1) and (2) were characterized using elemental analyses, spectral and other physicochemical methods. Single crystal X-ray diffraction measurements for (1) and (2) have been made to define the molecular aggregates and crystalline architectures. In (1), each copper (II) center adopts a distorted square pyramidal geometry with a CuN3OCl chromophore linked through μ-L1 to form the 1D polymeric chain. While in (2) each Ni(II) cation is six-coordinate with octahedral structure having NiN4O2 chromophore containing two L2 units each functioning as a classical tridentate (N,N,O) chelator. Different weak non-covalent interactions promote dimensionalities in the compounds. A Hirshfeld surface analysis was employed to gain additional insight into interactions responsible for packing of (1) and (2). Magnetic susceptibility measurement of (1) in the 4-300 K range reveals simple paramagnetism.

  9. Cyanide ion complexation by a cationic borane.

    Science.gov (United States)

    Chiu, Ching-Wen; Gabbaï, François P

    2008-02-14

    While we have previously reported that [1-(Mes2B)-8-(Me3NCH2)-C10H6]+ ([2]+) complexes fluoride ions to form [1-(Mes2FB)-8-(Me3NCH2)-C10H6] (2-F), we now show that this cationic borane also complexes cyanide to form [1-(Mes2(NC)B)-8-(Me3NCH2)-C10H6] (2-CN). This reaction also occurs under biphasic conditions (H2O-CHCl3) and may serve to transport cyanide in organic phases. The zwitterionic cyanoborate 2-CN has been fully characterized and its crystal structure determined. UV-vis titration experiments carried out in THF indicate that [2]+ has a higher affinity for fluoride (K > 10(8) M(-1)) than cyanide (K = 8.0 (+/-0.5) x 10(5) M(-1)). Steric effects which impede cyanide binding to the sterically congested boron center of [2]+ are most likely at the origin of this selectivity. Finally, electrochemical studies indicate that [2]+ is significantly more electrophilic than its neutral precursor 1-(Mes2B)-8-(Me2NCH2)-(C10H6) (1). These studies also show that reduction of [2]+ is irreversible, possibly because of elimination of the NMe3 moiety under reductive conditions. In fact, [2]OTf reacts with NaBH4 to afford 1-(Mes2B)-8-(CH3)-(C10H6) (4) which has also been fully characterized.

  10. Behaviour of the recoil atom in anionic, cationic and double Co-complexes

    International Nuclear Information System (INIS)

    Di Risio, C.; Marques, R.O.

    1984-01-01

    Thermal annealing of damages caused by the (n, γ) reaction in solid phase cobalt complexes has been studied. This study is based on the annealing of cationic and anionic sites for cis-[Co(en) 2 (NO 2 ) 2 ] [CoEDTA] 3H 2 O, in comparison with the behaviour of simple complexes like cis-[Co(en) 2 (NO 2 ) 2 ] Cl and [CoEDTA] 2 Ba.4H 2 O (en: etilendiamin). Competition between the annealing and chemical descomposition processes is analyzed for different crystalline systems. The separation of the different chemical species was carried out by paper electrophoresis. Using isothermal annealing analysis data, speed constants for each reaction are obtained. (author) [es

  11. Chemical bonding and structural ordering of cations in silicate glasses

    International Nuclear Information System (INIS)

    Calas, G.; Cormier, L.; Galoisy, L.; Ramos, A.; Rossano, St.

    1997-01-01

    The specific surrounding of cations in multicomponent silicate glasses is briefly presented. Information about interatomic distances and site geometry may be gained by using spectroscopic methods among which x-ray absorption spectroscopy may be used for the largest number of glass components. Scattering of x-rays and neutrons may also be used to determine the importance of medium range order around specific cations. All the existing data show that cations occur in sites with a well-defined geometry, which are in most cases connected to the silicate polymeric network. Medium range order has been detected around cations such as Ti, Ca and Ni, indicating that these elements have an heterogeneous distribution within the glassy matrix. (authors)

  12. After-Effects of the Cobalt-57-Iron-57 Electron-Capture Reaction in Hexacyanocobaltate (III) Complexes

    DEFF Research Database (Denmark)

    Fenger, Jørgen Folkvard; Siekierska, K.E.; Olsen, J.

    1973-01-01

    Isomorphous hexacyanocobaltate(III) complexes with the bivalent metal cations Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, and Cd2+ have been labelled with 57Co and used as Mössbauer sources. Whilst the spectrum of the complex Fe3[57Co(CN)6]2 can be resolved into a single line corresponding to the ion Fe II...

  13. Characterization of gadolinia-doped ceria with manganese addition synthesized by the cation complexation technique; Caracterizacao de ceria-gadolinia e ceria-gadolinia-manganes sintetizados pelo metodo de complexacao de cations

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J.D.; Muccillo, R.; Muccillo, E.N.S., E-mail: enavarro@usp.b [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais; Rocha, R.A. [Universidade Federal do ABC (CEMCSA/UFABC), Santo Andre, SP (Brazil). Centro de Engenharia, Modelagem e Ciencias Sociais Aplicadas

    2010-07-01

    Ceria-based compounds may be used for several technological applications like catalysts, grinding media and materials for electrolyte and electrodes in solid oxide fuel cells. For most of these applications fine powders are required. In this work, nanostructured ceria powders containing 20 mol % gadolinia with and without manganese addition were synthesized by the cation complexation technique. The prepared powders were calcined at 600 deg C for thermal decomposition of the metal citrate precursors. Results of X-ray diffraction, scanning electron microscopy and specific surface area evidenced the role of manganese on physical characteristics of the nanostructured materials. The cation complexation technique revealed to be a promising method for obtaining nanostructured powders with high yield and suitable physical properties for several technological applications. (author)

  14. D/H isotope effects in π-complexes of deuterated hexamethylbenzenes with the nitrosonium cation

    International Nuclear Information System (INIS)

    Borodkin, G.I.; Elanov, I.R.; Shakirov, M.M.; Shubin, V.G.

    1993-01-01

    The isotope effects of deuterium, manifested in the 13 C NMR spectra of complexes of deuterated hexamethylbenzenes C 6 (CD 3 ) n ·(CH 3 ) 6-n with the nitrosonium cation, have been studied. The small values observed for the isotopic perturbation are evidence of π-bonding of the NO + group to the hexamethylbenzene molecule. The applicability of an additive scheme of calculation of isotope effects for the ring carbon atoms of the complexes, based on the increment of replacement of the CH 3 group by CD 3 in hexamethylbenzene, has been demonstrated

  15. Synthesis and characterization of a cationic phthalimido-functionalized N-heterocyclic carbene complex of palladium(II) and its catalytic activity

    KAUST Repository

    Goh, Li Min Serena; Hogerl, Manuel Peter; Jokic̈, Nadežda B.; Tanase, Alexandrina D.; Bechlars, Bettina; Baratta, Walter; Mí nk, Já nos; Kü hn, Fritz

    2014-01-01

    A cationic phthalimido-functionalized N-heterocyclic carbene (NHC) palladium(II) complex has been synthesized from [3-methyl-1-(2′- phthalimidoethyl)imidazolium] hexafluorophosphate ([NHCMe,PhtH] PF6) by transmetalation and isolated in 67 % yield. The title complex has been applied as catalyst in the Suzuki-Miyaura cross-coupling reaction under benign aqueous conditions. The catalyst is active without any observable initiation period. High average turnover frequencies (TOFs) of up to 55000 h-1 have been reached with catalyst concentrations as low as 0.01 mol-%. A cationic phthalimido-functionalized N-heterocyclic carbene (NHC) palladium(II) complex has been prepared in high yield. The complex was activated instantly, without an initiation period, in the Suzuki-Miyaura cross-coupling reaction under benign aqueous aerobic conditions. Turnover frequencies (TOFs) up to 55000 h-1, were achieved with 0.01 mol-% of the complex. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Synthesis and characterization of a cationic phthalimido-functionalized N-heterocyclic carbene complex of palladium(II) and its catalytic activity

    KAUST Repository

    Goh, Li Min Serena

    2014-01-29

    A cationic phthalimido-functionalized N-heterocyclic carbene (NHC) palladium(II) complex has been synthesized from [3-methyl-1-(2′- phthalimidoethyl)imidazolium] hexafluorophosphate ([NHCMe,PhtH] PF6) by transmetalation and isolated in 67 % yield. The title complex has been applied as catalyst in the Suzuki-Miyaura cross-coupling reaction under benign aqueous conditions. The catalyst is active without any observable initiation period. High average turnover frequencies (TOFs) of up to 55000 h-1 have been reached with catalyst concentrations as low as 0.01 mol-%. A cationic phthalimido-functionalized N-heterocyclic carbene (NHC) palladium(II) complex has been prepared in high yield. The complex was activated instantly, without an initiation period, in the Suzuki-Miyaura cross-coupling reaction under benign aqueous aerobic conditions. Turnover frequencies (TOFs) up to 55000 h-1, were achieved with 0.01 mol-% of the complex. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Synthesis and characterization of heterobimetallic complexes of the type [Cu(pn2][MCl4] where M = Co(II, Ni(II, Cu(II, Zn(II, Cd(II, and Hg(II

    Directory of Open Access Journals (Sweden)

    Seema Yadav

    2016-11-01

    Full Text Available A series of new bimetallic transition metal complexes of the type [Cu(pn2] [MCl4] have been synthesized (where M = Co(II, Ni(II, Cu(II, Zn(II, Cd(II and Hg(II, pn = 1,3-diaminopropane and characterized by elemental analysis, molar conductance, TGA, IR and electronic spectra. All the compounds are 1:1 electrolyte in DMF. The Cu(II ion is square-planar while metal ions in the anionic moiety acquire their usual tetrahedral arrangement. On the basis of these studies it is concluded that anionic moiety is electrically stabilized by its cationic counterpart.

  18. Complexes of poly(ethylene glycol)-based cationic random copolymer and calf thymus DNA: a complete biophysical characterization.

    Science.gov (United States)

    Nisha, C K; Manorama, Sunkara V; Ganguli, Munia; Maiti, Souvik; Kizhakkedathu, Jayachandran N

    2004-03-16

    Complete biophysical characterization of complexes (polyplexes) of cationic polymers and DNA is needed to understand the mechanism underlying nonviral therapeutic gene transfer. In this article, we propose a new series of synthesized random cationic polymers (RCPs) from methoxy poly(ethylene glycol) monomethacrylate (MePEGMA) and (3-(methacryloylamino)propyl)trimethylammonium chloride with different mole ratios (32:68, 11:89, and 6:94) which could be used as a model system to address and answer the basic questions relating to the mechanism of the interaction of calf thymus DNA (CT-DNA) and cationic polymers. The solubility of the complexes of CT-DNA and RCP was followed by turbidity measurements. It has been observed that complexes of RCP with 68 mol % MePEGMA precipitate near the charge neutralization point, whereas complexes of the other two polymers are water-soluble and stable at all compositions. Dnase 1 digestion experiments show that DNA is inaccessible when it forms complexes with RCP. Ethidium bromide exclusion and gel electrophoretic mobility show that both polymers are capable of binding with CT-DNA. Atomic force microscopy images in conjunction with light scattering experiments showed that the complexes are spherical in nature and 75-100 nm in diameter. Circular dichroism spectroscopy studies indicated that the secondary structure of DNA in the complexes is not perturbed due to the presence of poly(ethylene glycol) segments in the polymer. Furthermore, we used a combination of spectroscopic and calorimetric techniques to determine complete thermodynamic profiles accompanying the helix-coil transition of CT-DNA in the complexes. UV and differential scanning calorimetry melting experiments revealed that DNA in the complexes is more stable than in the free state and the extent of stability depends on the polymer composition. Isothermal titration calorimetry experiments showed that the binding of these RCPs to CT-DNA is associated with small exothermic

  19. Complexation of amidocarbamoyl phosphine oxides with Ln+3 (Ln = La, Nd, Pm, Sm and Eu) cation series: structural and thermodynamical features

    International Nuclear Information System (INIS)

    Hosseinnejad, Tayebeh; Kazemi, Tayebeh

    2016-01-01

    In the present study, we have mainly investigated the nature of interactions in Ln 3+ (Ln = La, Nd, Pm, Sm, Eu) complexes with amidocarbamoyl methyl phosphine oxide (CMPO) and amidocarbamoyl propyl phosphine oxide (CPPO) ligands based on density functional theory (DFT) approaches. In the first step, thermodynamical properties for complexation of CMPO and CPPO ligands with Ln 3+ cation series have been determined in the gas phase and with the presence of three solvents: n-hexane, chloroform and toluene, via polarized continuum model (PCM) computations. The trend of metal-ligand interaction strength has been analyzed and compared with the trend of ionic hardness within the series of lanthanide cations and different size of alkyl chain of amidocarbamoyl phosphine oxide ligand. The calculated thermochemical results in the gas and solution phases reveals that there is a consistency between increasing trend in the hardness of Ln 3+ cation series and also electron-donating property of alkyl chain with increasing in thermodynamical stability of [Ln-CMPO] 3+ and [Ln-CPPO] 3+ complex series. We have also demonstrated that in the complexation reaction of all complex series, using n-hexane as solvent is more favorable thermodynamically than chloroform and toluene. It should be stated that this issue has been observed in many experiments. Finally, analysis of calculated deformation energies and also the variation in bond order of some selected key bonds in CMPO and CPPO ligands and their corresponded Ln 3+ complexes series show a similar trend with increasing in the hardness of Ln 3+ cation series and electron-donating of alkyl chain of amidocarbamoyl phosphine oxide ligand.

  20. Coordination functionalization of graphene oxide with tetraazamacrocyclic complexes of nickel(II): Generation of paramagnetic centers

    Energy Technology Data Exchange (ETDEWEB)

    Basiuk, Vladimir A., E-mail: basiuk@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510 México D.F. (Mexico); Department of Chemistry,Tufts University, 62 Talbot Avenue, Medford, MA 02155 (United States); Alzate-Carvajal, Natalia [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510 México D.F. (Mexico); Henao-Holguín, Laura V. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510 México D.F. (Mexico); Rybak-Akimova, Elena V. [Department of Chemistry,Tufts University, 62 Talbot Avenue, Medford, MA 02155 (United States); Basiuk, Elena V., E-mail: elbg1111@gmail.com [Department of Chemistry,Tufts University, 62 Talbot Avenue, Medford, MA 02155 (United States); Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510 México D.F. (Mexico)

    2016-05-15

    Highlights: • [Ni(cyclam)]{sup 2+} and [Ni(tet b)]{sup 2+} cations coordinate to carboxylic groups of GO. • The coordination takes place under basic conditions in aqueous-based medium. • The coordination results in the conversion from low-spin to high-spin Ni(II). • Functionalized GO samples were characterized by various instrumental techniques. - Abstract: We describe a novel approach to functionalization of graphene oxide (GO) which allows for a facile generation of paramagnetic centers from two diamagnetic components. Coordination attachment of [Ni(cyclam)]{sup 2+} or [Ni(tet b)]{sup 2+} tetraazamacrocyclic cations to carboxylic groups of GO takes place under basic conditions in aqueous-based reaction medium. The procedure is very straightforward and does not require high temperatures or other harsh conditions. Changing the coordination geometry of Ni(II) from square-planar tetracoordinated to pseudooctahedral hexacoordinated brings about the conversion from low-spin to high-spin state of the metal centers. Even though the content of tetraazamacrocyclic complexes in functionalized GO samples was found to be relatively low (nickel content of ca. 1 wt%, as determined by thermogravimetric analysis, elemental analysis and energy dispersive X-ray spectroscopy), room temperature magnetic susceptibility measurements easily detected the appearance of paramagnetic properties in GO + [Ni(cyclam)] and GO + [Ni(tet b)] nanohybrids, with effective magnetic moments of 1.95 BM and 2.2 BM for, respectively. According to density functional theory calculations, the main spin density is localized at the macrocyclic complexes, without considerable extension to graphene sheet, which suggests insignificant ferromagnetic coupling in the nanohybrids, in agreement with the results of magnetic susceptibility measurements. The coordination attachment of Ni(II) tetraazamacrocycles to GO results in considerable changes in Fourier-transform infrared and X-ray photoelectron spectra

  1. Modelling Ni diffusion in bentonite using different sorption models

    International Nuclear Information System (INIS)

    Pfingsten, W.; Baeyens, B.; Bradbury, M.

    2010-01-01

    Document available in extended abstract form only. An important component of the multi barrier disposal concept for a radioactive waste repository is the bentonite backfill surrounding the canisters containing vitrified high-level waste and spent fuel located in the tunnels deep within the chosen host rock. The effectiveness of the compacted bentonite barrier is such that calculations have indicated that many radionuclides have decayed to insignificant levels before having diffused through the thickness of bentonite. These calculations are performed using the simple Kd sorption concept in which the values are taken from batch type experiments performed on dispersed systems performed for a single metal at a time, usually at trace concentrations. However, in such complex systems many radionuclides, inactive metal contaminants/ground water components may be simultaneously present in the aqueous phase at a range of concentrations varying with time during the temporal evolution of the repository system. An important aspect influencing the sorption of any radioactive metal under a set of given geochemical conditions is its competition with other metals present, and how this may vary as a function of concentration. Competitive sorption effects are not currently included in safety assessments and are thus an issue which needs to be addressed. Here we provide some first estimates of the potential influence of competitive sorption effects on the migration of radioactive metals through compacted bentonite as a function of their concentration and the concentration of competing metals. Ni(II) and Fe(II) were chosen as possible competing cations since their concentration levels are expected to have values greater than trace levels and effects might be maximal and canister corrosion represents a permanent Fe source at the bentonite interface which could influence bivalent radionuclide diffusion. The modelling of the Ni(II) diffusion/sorption has been carried out using three

  2. Micellar effect on metal-ligand complexes of Co(II, Ni(II, Cu(II and Zn(II with citric acid

    Directory of Open Access Journals (Sweden)

    Nageswara Rao Gollapalli

    2009-12-01

    Full Text Available Chemical speciation of citric acid complexes of Co(II, Ni(II, Cu(II and Zn(II was investigated pH-metrically in 0.0-2.5% anionic, cationic and neutral micellar media. The primary alkalimetric data were pruned with SCPHD program. The existence of different binary species was established from modeling studies using the computer program MINIQUAD75. Alkalimetric titrations were carried out in different relative concentrations (M:L:X = 1:2:5, 1:3:5, 1:5:3 of metal (M to citric acid. The selection of best chemical models was based on statistical parameters and residual analysis. The species detected were MLH, ML2, ML2H and ML2H2. The trend in variation of stability constants with change in mole fraction of the medium is explained on the basis of electrostatic and non-electrostatic forces. Distributions of the species with pH at different compositions of micellar media are also presented.

  3. Structural and dielectric studies of LiNiPO4 and LiNi0.5Co0.5PO4 cathode materials for lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    K. Vijaya Babu

    2016-09-01

    Full Text Available Olivine-type LiNiPO4 has been considered as a most competitive positive electrode active material for lithium-ion batteries. In the present paper, the LiNiPO4 and Co-doped LiNi0.5Co0.5PO4 are synthesized by solid-state reaction method under air atmosphere. All the X-ray diffraction peaks of both the compounds are indexed and it is found that the samples are well crystallized in orthorhombic olivine structure belonging to the space group Pnma. The crystallite size is calculated from the Scherrer formula and it is found to be 6.918 and 4.818 nm for pure and doped samples, respectively. The surface morphology and grain sizes of the materials are investigated through scanning electron microscope. Presence of preferred local cation environment is understood from Fourier transform infrared spectroscopy (FTIR studies. The conductivity and dielectric analysis of the samples are carried out at different temperatures and frequencies using the complex impedance spectroscopy technique. The electrical conductivity of LiNi0.5Co0.5PO4 is higher than that of pure LiNiPO4.

  4. Anchoring cationic amphiphiles for nucleotide delivery: significance of DNA release from cationic liposomes for transfection.

    Science.gov (United States)

    Hirashima, Naohide; Minatani, Kazuhiro; Hattori, Yoshifumi; Ohwada, Tomohiko; Nakanishi, Mamoru

    2007-06-01

    We have designed and synthesized lithocholic acid-based cationic amphiphile molecules as components of cationic liposomes for gene transfection (lipofection). To study the relationship between the molecular structures of those amphiphilic molecules, particularly the extended hydrophobic appendant (anchor) at the 3-hydroxyl group, and transfection efficiency, we synthesized several lithocholic and isolithocholic acid derivatives, and examined their transfection efficiency. We also compared the physico-chemical properties of cationic liposomes prepared from these derivatives. We found that isolithocholic acid derivatives exhibit higher transfection efficiency than the corresponding lithocholic acid derivatives. This result indicates that the orientation and extension of hydrophobic regions influence the gene transfection process. Isolithocholic acid derivatives showed a high ability to encapsulate DNA in a compact liposome-DNA complex and to protect it from enzymatic degradation. Isolithocholic acid derivatives also facilitated the release of DNA from the liposome-DNA complex, which is a crucial step for DNA entry into the nucleus. Our results show that the transfection efficiency is directly influenced by the ability of the liposome complex to release DNA, rather than by the DNA-encapsulating ability. Molecular modeling revealed that isolithocholic acid derivatives take relatively extended conformations, while the lithocholic acid derivatives take folded structures. Thus, the efficiency of release of DNA from cationic liposomes in the cytoplasm, which contributes to high transfection efficiency, appears to be dependent upon the molecular shape of the cationic amphiphiles.

  5. Ni doped Fe3O4 magnetic nanoparticles.

    Science.gov (United States)

    Larumbe, S; Gómez-Polo, C; Pérez-Landazábal, J I; García-Prieto, A; Alonso, J; Fdez-Gubieda, M L; Cordero, D; Gómez, J

    2012-03-01

    In this work, the effect of nickel doping on the structural and magnetic properties of Fe3O4 nanoparticles is analysed. Ni(x)Fe(3-x)O4 nanoparticles (x = 0, 0.04, 0.06 and 0.11) were obtained by chemical co-precipitation method, starting from a mixture of FeCl2 x 4H2O and Ni(AcO)2 x 4H2O salts. The analysis of the structure and composition of the synthesized nanoparticles confirms their nanometer size (main sizes around 10 nm) and the inclusion of the Ni atoms in the characteristic spinel structure of the magnetite Fe3O4 phase. In order to characterize in detail the structure of the samples, X-ray absorption (XANES) measurements were performed on the Ni and Fe K-edges. The results indicate the oxidation of the Ni atoms to the 2+ state and the location of the Ni2+ cations in the Fe2+ octahedral sites. With respect to the magnetic properties, the samples display the characteristic superparamagnetic behaviour, with anhysteretic magnetic response at room temperature. The estimated magnetic moment confirms the partial substitution of the Fe2+ cations by Ni2+ atoms in the octahedral sites of the spinel structure.

  6. Adsorption and desorption behaviors of cationic liposome-DNA complexes upon lipofection in inside and outside biomembrane models using a dynamic quasi-elastic laser scattering method.

    Science.gov (United States)

    Uchiyama, Yoshiko; Yui, Hiroharu; Sawada, Tsuguo

    2004-11-01

    The dynamic behaviors of cationic liposome-DNA complexes in inside and outside biomembrane models upon lipofection were investigated using the time-resolved quasi-elastic laser scattering (QELS) method. Inside and outside biomembrane models with similar phospholipid compositions to those in living cells were formed at a tetradecane/phosphate buffered saline (TD/PBS) interface. Cationic liposome-DNA complexes were injected into the buffer subphase, and their adsorption/desorption behaviors at the biomembrane models were monitored through changes in the interfacial tension. We found that the adsorption rate of the complexes increased 2.6 times more in the outside model than in the inside one. The adsorption rate of DNA alone did not show a remarkable difference from one side to the other; however, the adsorption rate of the cationic liposome alone showed a similar tendency to that of the liposome-DNA complex. These results indicated that the difference in lipid composition induced a different dynamic behavior of exogenous biomolecules and that the cationic liposomes played an important role in the faster incorporation of DNA into cells upon lipofection.

  7. Synthesis and molecular structure of [Cu(NH3)4][Ni(CN)4]: A missing piece in the [Cu(NH3)n][Ni(CN)4] story

    Science.gov (United States)

    Solanki, Dina; Hogarth, Graeme

    2015-11-01

    Reaction of CuCl2·2H2O and K2[Ni(CN)4]·2H2O in aqueous ammonia gave blue rod-like crystals of [Cu(NH3)4][Ni(CN)4]. An X-ray crystallographic reveals that square-planar anions and cations are weakly associated through coordination of a cis pair of cyanide ligands to copper, with one short and one long contact and thus the copper centre is best described as a square-based pyramid. Crystals lose ammonia readily upon removal from the solvent and this has been probed by TGA and DSC measurements. For comparison we have also re-determined the structure of the related ethylenediamine (en) complex [Cu(en)2][Ni(CN)4] at 150 K. This consists of a 1D chain in which a trans pair of cyanide ligands bind to copper such that the latter has an overall tetragonally distorted octahedral coordination geometry.

  8. Ferro- to antiferromagnetic crossover angle in diphenoxido- and carboxylato-bridged trinuclear Ni(II)₂-Mn(II) complexes: experimental observations and theoretical rationalization.

    Science.gov (United States)

    Seth, Piya; Figuerola, Albert; Jover, Jesús; Ruiz, Eliseo; Ghosh, Ashutosh

    2014-09-02

    Three new trinuclear heterometallic Ni(II)-Mn(II) complexes have been synthesized using a [NiL] metalloligand, where H2L = N,N'-bis(salicylidene)-1,3-propanediamine. The complexes [(NiL)2Mn(OCnn)2(CH3OH)2]·CH3OH (1), [(NiL)2Mn(OPh)2(CH3OH)2][(NiL)2Mn(OPh)2]·H2O (2), and [(NiL)2Mn(OSal)2(CH3OH)2]·2[NiL] (3) (where OCnn = cinnamate, OPh = phenylacetate, OSal = salicylate) have been structurally characterized. In all three complexes, in addition to the double phenoxido bridge, the two terminal Ni(II) atoms are linked to the central Mn(II) by means of a syn-syn bridging carboxylate, giving rise to a linear structure. Complexes 1 and 2 with Ni-O-Mn angles of 97.24 and 96.43°, respectively, exhibit ferromagnetic interactions (J(Ni-Mn) = +1.38 and +0.50 cm(-1), respectively), whereas 3 is antiferromagnetic (J(Ni-Mn) = -0.24 cm(-1)), having an Ni-O-Mn angle of 98.51°. DFT calculations indicate that there is a clear magneto-structural correlation between the Ni-O-Mn angle and J(Ni-Mn) values, which is in agreement with the experimental results.

  9. Absence of Ni on the outer surface of Sr doped La 2 NiO 4 single crystals

    KAUST Repository

    Burriel, Mó nica; Wilkins, Stuart; Hill, John P.; Muñ oz-Má rquez, Miguel A.; Brongersma, Hidde H.; Kilner, John A.; Ryan, Mary P.; Skinner, Stephen J.

    2014-01-01

    A combination of surface sensitive techniques was used to determine the surface structure and chemistry of La2-xSrxNiO 4+δ. These measurements unequivocally showed that Ni is not present in the outermost atomic layer, suggesting that the accepted model with the B-site cations exposed to the environment is incorrect. © 2014 The Royal Society of Chemistry.

  10. Synthesis, NMR characterization, X-ray crystal structure of Co(II) Ni(II) and Cu(II) complexes of a pyridine containing self-assembling

    International Nuclear Information System (INIS)

    Ranjbar, M.; Taghavipour, M.; Moghimi, A.; Aghabozorg, H.

    2002-01-01

    In the recent years, the self-assembling systems have been attracted chemists. The intermolecular bond in such systems mainly consists of ion pairing and hydrogen bonding [1,2]. The reaction between self-assembling system liquid LH 2 (py dc=2,6-pyridinedicarboxylic acid and py da=2,6- pyridine diamin) with cobalt (II) nitrate, nickel (II) chloride, and copper (II) acetate in water leads to the formation of self- assemble coordination complexes, [py da.H] 2 [M(py dc) 2 ]. H 2 O, M=Co(II),Ni(II), and Cu(II). The characterization was performed using elemental analysis, ESI mass spectroscopy, 1 H and 13 C NMR and X-ray crystallography. The crystal systems are monoclinic with space group P2 1 /n and four molecules per unit cell. These complexes shows 13 C NMR resonances of cationic counter ion [(py dc,H)] + in DMSO- d 6 but no signal corresponding to the two coordinated ligands [py dc] 2- The metal atoms are six-coordinated with a distorted octahedral geometry. The two [py de] 2- units are almost perpendicular to each other

  11. Heteroleptic and Homoleptic Iron(III Spin-Crossover Complexes; Effects of Ligand Substituents and Intermolecular Interactions between Co-Cation/Anion and the Complex

    Directory of Open Access Journals (Sweden)

    Wasinee Phonsri

    2017-08-01

    Full Text Available The structural and magnetic properties of a range of new iron(III bis-tridentate Schiff base complexes are described with emphasis on how intermolecular structural interactions influence spin states and spin crossover (SCO in these d5 materials. Three pairs of complexes were investigated. The first pair are the neutral, heteroleptic complexes [Fe(3-OMe-SalEen(thsa] 1 and [Fe(3-MeOSalEen(3-EtOthsa] 2, where 3-R-HSalEen = (E-2-(((2-(ethylaminoethyliminomethyl-6-R-phenol and 3-R-H2thsa = thiosemicarbazone-3-R-salicylaldimine. They display spin transitions above room temperature. However, 2 shows incomplete and gradual change, while SCO in 1 is complete and more abrupt. Lower cooperativity in 2 is ascribed to the lack of π–π interactions, compared to 1. The second pair, cationic species [Fe(3-EtOSalEen2]NO3 3 and [Fe(3-EtOSalEen2]Cl 4 differ only in the counter-anion. They show partial SCO above room temperature with 3 displaying a sharp transition at 343 K. Weak hydrogen bonds from cation to Cl− probably lead to weaker cooperativity in 4. The last pair, CsH2O[Fe(3-MeO-thsa2] 5 and Cs(H2O2[Fe(5-NO2-thsa2] 6, are anionic homoleptic chelates that have different substituents on the salicylaldiminate rings of thsa2−. The Cs cations bond to O atoms of water and the ligands, in unusual ways thus forming attractive 1D and 3D networks in 5 and 6, respectively, and 5 remains HS (high spin at all temperatures while 6 remains LS (low spin. Comparisons are made to other literature examples of Cs salts of [Fe(5-R-thsa2]− (R = H and Br.

  12. Asymmetric synthesis of α-amino acids via homologation of Ni(II) complexes of glycine Schiff bases; Part 1: alkyl halide alkylations.

    Science.gov (United States)

    Sorochinsky, Alexander E; Aceña, José Luis; Moriwaki, Hiroki; Sato, Tatsunori; Soloshonok, Vadim A

    2013-10-01

    Alkylations of chiral or achiral Ni(II) complexes of glycine Schiff bases constitute a landmark in the development of practical methodology for asymmetric synthesis of α-amino acids. Straightforward, easy preparation as well as high reactivity of these Ni(II) complexes render them ready available and inexpensive glycine equivalents for preparing a wide variety of α-amino acids, in particular on a relatively large scale. In the case of Ni(II) complexes containing benzylproline moiety as a chiral auxiliary, their alkylation proceeds with high thermodynamically controlled diastereoselectivity. Similar type of Ni(II) complexes derived from alanine can also be used for alkylation providing convenient access to quaternary, α,α-disubstituted α-amino acids. Achiral type of Ni(II) complexes can be prepared from picolinic acid or via recently developed modular approach using simple secondary or primary amines. These Ni(II) complexes can be easily mono/bis-alkylated under homogeneous or phase-transfer catalysis conditions. Origin of diastereo-/enantioselectivity in the alkylations reactions, aspects of practicality, generality and limitations of this methodology is critically discussed.

  13. Complexation of amidocarbamoyl phosphine oxides with Ln{sup +3} (Ln = La, Nd, Pm, Sm and Eu) cation series: structural and thermodynamical features

    Energy Technology Data Exchange (ETDEWEB)

    Hosseinnejad, Tayebeh; Kazemi, Tayebeh [Alzahra Univ., Tehran (Iran, Islamic Republic of). Dept. of Chemistry

    2016-05-01

    In the present study, we have mainly investigated the nature of interactions in Ln{sup 3+} (Ln = La, Nd, Pm, Sm, Eu) complexes with amidocarbamoyl methyl phosphine oxide (CMPO) and amidocarbamoyl propyl phosphine oxide (CPPO) ligands based on density functional theory (DFT) approaches. In the first step, thermodynamical properties for complexation of CMPO and CPPO ligands with Ln{sup 3+} cation series have been determined in the gas phase and with the presence of three solvents: n-hexane, chloroform and toluene, via polarized continuum model (PCM) computations. The trend of metal-ligand interaction strength has been analyzed and compared with the trend of ionic hardness within the series of lanthanide cations and different size of alkyl chain of amidocarbamoyl phosphine oxide ligand. The calculated thermochemical results in the gas and solution phases reveals that there is a consistency between increasing trend in the hardness of Ln{sup 3+} cation series and also electron-donating property of alkyl chain with increasing in thermodynamical stability of [Ln-CMPO]{sup 3+} and [Ln-CPPO]{sup 3+} complex series. We have also demonstrated that in the complexation reaction of all complex series, using n-hexane as solvent is more favorable thermodynamically than chloroform and toluene. It should be stated that this issue has been observed in many experiments. Finally, analysis of calculated deformation energies and also the variation in bond order of some selected key bonds in CMPO and CPPO ligands and their corresponded Ln{sup 3+} complexes series show a similar trend with increasing in the hardness of Ln{sup 3+} cation series and electron-donating of alkyl chain of amidocarbamoyl phosphine oxide ligand.

  14. Experimental and DFT study on the complexation of the silver cation with calix[4]arene-bis(t-octylbenzo-18-crown-6)

    International Nuclear Information System (INIS)

    Makrlik, E.; Toman, P.; Vanura, P.

    2013-01-01

    From extraction experiments and γ-activity measurements, the exchange extraction constant corresponding to the equilibrium Ag + (aq) + 1 x Cs + (org) ⇔ 1 x Ag + (org) + Cs + (aq) taking place in the two-phase water-phenyltrifluoromethyl sulfone (FS 13) system (1 = calix[4]arene-bis(t-octylbenzo-18-crown-6); aq = aqueous phase, org = FS 13 phase) was evaluated as logK ex (Ag + , 1 x Cs + ) = -1.5 ± 0.1. Further, the stability constant of the 1 x Ag + complex in FS 13 saturated with water was calculated for a temperature of 25 deg C: log β org(1 x Ag + ) = 10.1 ± 0.2. Finally, by using quantum mechanical DFT calculations, the most probable structure of the cationic complex species 1 x Ag + was derived. In the resulting 1 x Ag + complex, the 'central' cation Ag + is bound by eight bond interactions to six oxygen atoms from the respective 18-crown-6 moiety and to two carbons of the corresponding two benzene rings of the parent ligand 1 via cation-π interaction. (author)

  15. ANOMALOUS ELECTRODEPOSITION OF Fe-Ni ALLOY COATING FROM SIMPLE AND COMPLEX BATHS AND ITS MAGNETIC PROPERTY

    Directory of Open Access Journals (Sweden)

    M A Islam

    2010-03-01

    Full Text Available Electrodeposition of Fe-Ni thin films has been carried on copper substrate under various electrodeposition conditions from two simple and six complex baths. Sulfate baths composing of NiSO4. 7H2O, FeSO4.7H2O, H3BO3 and Na2SO4KEYWORDS: Anomalous Electrodeposition, Fe-Ni Coating, Complexing agent, Current Density, Magnetic Property. 1. INTRODUCTION Alloy electrodeposition technologies can extend tremendously the potential of electrochemical deposition processes to provide coatings that require unique mechanical, chemical and physical properties [1]. There has been a great research interest in the development and characterization of iron-nickel (Fe-Ni thin films due to their operational capacity, economic interest, magnetic and other properties [2]. Due to their unique low coefficient of thermal expansion (CTE and soft magnetic properties, Fe-Ni alloys have been used in industrial applications for over 100 years [3]. Typical examples of applications that are based on the low CTE of Fe-Ni alloys include: thermostatic bimetals, glass sealing, integrated circuit packaging, cathode ray tube, shadow masks, membranes for liquid natural gas tankers; applications based on the soft magnetic properties include: read-write heads for magnetic storage, magnetic actuators, magnetic shielding, high performance transformer cores. comprise the simple baths whereas complex baths were prepared by adding ascorbic acid, saccharin and citric acid in simple baths. The effect of bath composition, pH and applied current density on coating appearance, composition, morphology and magnetic property were studied. Wet chemical analysis technique was used to analyze the coating composition whereas SEM and VSM were used to study the deposit morphology and magnetic property respectively. Addition of complexing agents in plating baths suppressed the anomalous nature of Fe-Ni alloy electrodeposition. Coatings obtained from simple baths were characterized by coarse grained non

  16. Direct Observation of Very Large Zero-Field Splitting in a Tetrahedral Ni(II)Se4 Coordination Complex.

    Science.gov (United States)

    Jiang, Shang-Da; Maganas, Dimitrios; Levesanos, Nikolaos; Ferentinos, Eleftherios; Haas, Sabrina; Thirunavukkuarasu, Komalavalli; Krzystek, J; Dressel, Martin; Bogani, Lapo; Neese, Frank; Kyritsis, Panayotis

    2015-10-14

    The high-spin (S = 1) tetrahedral Ni(II) complex [Ni{(i)Pr2P(Se)NP(Se)(i)Pr2}2] was investigated by magnetometry, spectroscopic, and quantum chemical methods. Angle-resolved magnetometry studies revealed the orientation of the magnetization principal axes. The very large zero-field splitting (zfs), D = 45.40(2) cm(-1), E = 1.91(2) cm(-1), of the complex was accurately determined by far-infrared magnetic spectroscopy, directly observing transitions between the spin sublevels of the triplet ground state. These are the largest zfs values ever determined--directly--for a high-spin Ni(II) complex. Ab initio calculations further probed the electronic structure of the system, elucidating the factors controlling the sign and magnitude of D. The latter is dominated by spin-orbit coupling contributions of the Ni ions, whereas the corresponding effects of the Se atoms are remarkably smaller.

  17. Study of behaviour of Ni(III) macrocyclic complexes in acidic ...

    Indian Academy of Sciences (India)

    The Cu(II) ion-catalysed kinetics of oxidation of H2O2 by [NiIIIL] [where L ... The rate of the reaction of both complexes with hydrogen peroxide shows contrasting ... enhanced kinetic and thermodynamic stabilities. The redox chemistry of synthetic poly-aza macrocycles explores the properties of nickel containing enzymes.1.

  18. Reaction of Non-Symmetric Schiff Base Metallo-Ligand Complexes Possessing an Oxime Function with Ln Ions

    Directory of Open Access Journals (Sweden)

    Jean-Pierre Costes

    2018-03-01

    Full Text Available The preparation of non-symmetric Schiff base ligands possessing one oxime function that is associated to a second function such as pyrrole or phenol function is first described. These ligands, which possess inner N4 or N3O coordination sites, allow formation of cationic or neutral non-symmetric CuII or NiII metallo-ligand complexes under their mono- or di-deprotonated forms. In presence of Lanthanide ions the neutral complexes do not coordinate to the LnIII ions, the oxygen atom of the oxime function being only hydrogen-bonded to a water molecule that is linked to the LnIII ion. This surprising behavior allows for the isolation of LnIII ions by non-interacting metal complexes. Reaction of cationic NiII complexes possessing a protonated oxime function with LnIII ions leads to the formation of original and dianionic (Gd(NO352− entities that are well separated from each other. This work highlights the preparation of well isolated mononuclear LnIII entities into a matrix of diamagnetic metal complexes. These new complexes complete our previous work dealing with the complexing ability of the oxime function toward Lanthanide ions. It could open the way to the synthesis of new entities with interesting properties, such as single-ion magnets for example.

  19. Gas phase chemistry of N-benzylbenzamides with silver(I) cations: characterization of benzylsilver cation.

    Science.gov (United States)

    Sun, Hezhi; Jin, Zhe; Quan, Hong; Sun, Cuirong; Pan, Yuanjiang

    2015-03-07

    The benzylsilver cation which emerges from the collisional dissociation of silver(I)-N-benzylbenzamide complexes was characterized by deuterium-labeling experiments, theoretical calculations, breakdown curves and substituent effects. The nucleophilic attack of the carbonyl oxygen on an α-hydrogen results in the generation of the benzylsilver cation, which is competitive to the AgH loss with the α-hydrogen.

  20. Synthesis and properties of dioxo Tc(V) cationic complexes with nitrogen containing ligands

    International Nuclear Information System (INIS)

    Gambino, D.; Kremer, C.; Savio, E.; Leon, A.; Kremer, E.

    1990-01-01

    A series of Tc(V) cationic complexes was synthesized by electrochemical reduction of TcO 4 - . The electrolysis was performed in aqueous media containing amines as ligands: ethylenediamine (en), diethylenetriamine (dien), triethylenetetramine (trien) and 1,3-diaminopropane (1,3-dap). The combination of different techniques allows to propose the general formula [TcO 2 (amine) 2 ] + for these compounds. Electrodeposition of TcO 2 was a competitive reaction. The UV spectra were compared with those for other Tc(V) amine complexes. The presence of two peaks could be verified. Preliminary studies showed that kinetic stability decreased in the sequence en, 1,3-dap, trien, dien. The decomposition rate increased when the pH was lowered. (author) 16 refs.; 2 figs.; 3 tabs

  1. [Noncovalent cation-π interactions--their role in nature].

    Science.gov (United States)

    Fink, Krzysztof; Boratyński, Janusz

    2014-11-07

    Non-covalent interactions play an extremely important role in organisms. The main non-covalent interactions in nature are: ion-ion interactions, dipole-dipole interactions, hydrogen bonds, and van der Waals interactions. A new kind of intermolecular interactions--cation-π interactions--is gaining increasing attention. These interactions occur between a cation and a π system. The main contributors to cation-π interactions are electrostatic, polarization and, to a lesser extent, dispersion interactions. At first, cation-π interactions were studied in a gas phase, with metal cation-aromatic system complexes. The characteristics of these complexes are as follows: an increase of cation atomic number leads to a decrease of interaction energy, and an increase of cation charge leads to an increase of interaction energy. Aromatic amino acids bind with metal cations mainly through interactions with their main chain. Nevertheless, cation-π interaction with a hydrophobic side chain significantly enhances binding energy. In water solutions most cations preferentially interact with water molecules rather than aromatic systems. Cation-π interactions occur in environments with lower accessibility to a polar solvent. Cation-π interactions can have a stabilizing role on the secondary, tertiary and quaternary structure of proteins. These interactions play an important role in substrate or ligand binding sites in many proteins, which should be taken into consideration when the screening of effective inhibitors for these proteins is carried out. Cation-π interactions are abundant and play an important role in many biological processes.

  2. Study of the emission oxidative reactions of ruthenium (II) complex by cationic compounds in anionic micelles

    International Nuclear Information System (INIS)

    Bonilha, J.B.S.

    1985-01-01

    The oxidative quenching of the emission of the tetraanionic complex tris (4,4' dicarboxylate - 2,2' - bipyridine ruthenium (II) in aqueous solution, by both organic and inorganic compounds in presence of anionic detergents, above and below the critical micelle concentration is studied. The organic cations, the inorganic ion and detergents used are shown. (M.J.C.) [pt

  3. Interactions of nucleobases with alkali earth metal cations--electrospray ionization mass spectrometric study.

    Science.gov (United States)

    Frańska, Magdalena

    2007-01-01

    Interactions of nucleobases with alkali earth metal cations have been studied by electrospray ionization mass spectrometry (ESI-MS). Nucleobases containing at least one oxygen atom form stable complexes with alkali earth metal cations. This phenomenon can be explained on the grounds of the well known theory of hard and soft acids and bases. Uracil and thymine make complexes only when in their deprotonoted forms. The cations of great radii (Sr(2+), Ba(2+)) are more prone to form complexes of stoichiometry 1:1 with uracil and thymine than the cations of small radii (Mg(2+), Ca(2+)). On the other hand, Mg(2+) forms complexes of stoichiometry 2:1 and 3:2 with uracil and thymine. Gas-phase stabilities of the 1:1 complexes are higher for the cations of small radii, in contrast to the solution stabilities. For cytosine and 9- methylhypoxantine the 1:1 complexes of their deprotonated forms are observed at higher cone voltage as a result of HCl molecule loss from the complexes containing the counter ion (Cl(-)). In solution, more stable complexes are formed with metal cations of low radii. Gas-phase stability of the complexes formed by deprotonated 9- methyl-hypoxantine increases with increasing metal cation radius.

  4. Electronic, magnetic and optical properties of reduced hybrid layered complex Ni(pyz)V{sub 4}O{sub 10} (pyz=C{sub 4}H{sub 4}N{sub 2}) by first-principles

    Energy Technology Data Exchange (ETDEWEB)

    Munir, Junaid; Mat Isa, Ahmad Radzi [Physics Department, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Yousaf, Masood [IBS Center for Multidimensional Carbon Materials, Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Aliabad, H.A. Rahnamaye [Department of Physics, Hakim Sabzevari University (Iran, Islamic Republic of); Ain, Qurat-ul [Key Laboratory for Laser Plasamas (MOE) & Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Saeed, M.A., E-mail: saeed@utm.my [Physics Department, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia)

    2016-10-15

    This article reports the electronic, structure, magnetic and optical properties of reduced hybrid layered complex Ni(pyz)V{sub 4}O{sub 10} (pyz=C{sub 4}H{sub 4}N{sub 2}) studied by employing density functional theory with local density approximation (LDA), generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof-96 (PBE) and modified Becke–Johnson (mBJ) exchange-correlation potential and energy. The band structure and density of states of these compounds are also presented. The total density of states (DOS) for up and down spin states clearly split, which means that the exchange interaction causes the ordered spin arrangement. PBE-mBJ calculation reveals a wider band gap in spin down state, which shows a half-metallic electronic character at the equilibrium state. The spin-polarized calculations indicate metallic nature in orthorhombic crystalline phase. It is also noted that the optical conductivity for PBE-mBJ is larger than that of LDA and PBE-GGA. Furthermore, the results show a half-metallic ferromagnetic ground state for Ni(pyz)V{sub 4}O{sub 10} in PBE-mBJ potential. The present results suggest Ni(pyz)V{sub 4}O{sub 10} compound as a potential candidate for the future optoelectronic and spintronic applications. - Highlights: • First study of the electronic, structure, magnetic and optical properties of reduced hybrid layered complex Ni(pyz)V{sub 4}O{sub 10} (pyz=C{sub 4}H{sub 4}N{sub 2}) by first principles. • PBE-mBJ calculation reveals a wider band gap in spin down state indicating its half-metallic electronic character. • The large spin magnetic moment on Ni and V cations indicates the ferromagnetic interaction which makes this compound suitable candidate for spintronics applications. • An optical band gap reveals that this compound is also useful for the application in optoelectronics.

  5. Preparation of Iron-nickel Alloy Nanostructures via Two Cationic Pyridinium Derivatives as Soft Templates

    Directory of Open Access Journals (Sweden)

    Jingxin Zhou

    2015-09-01

    Full Text Available In this paper, crystalline iron-nickel alloy nanostructures were successfully prepared from two cationic pyridinium derivatives as soft templates in solution. The crystal structure and micrograph of FeNi alloy nanostructures were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, and the content was confirmed by energy-dispersive spectrometry. The results indicated that the as-prepared nanostructures showed slightly different diameter ranges with the change of cationic pyridinium derivatives on the surface. The experimental data indicated that the adsorption of cationic pyridinium compounds on the surface of particles reduces the surface charge, leading to an isotropic distribution of the residual surface charges. The magnetic behaviours of as-prepared FeNi alloy nanostructures exhibited disparate behaviours, which could be attributed to their grain sizes and distinctive structures. The present work may give some insight into the synthesis and character of new alloy nanomaterials with special nanostructures using new soft templates.

  6. Synthesis, characterization and antistructure modeling of Ni nano ferrite

    Science.gov (United States)

    Kane, S. N.; Raghuvanshi, S.; Satalkar, M.; Reddy, V. R.; Deshpande, U. P.; Tatarchuk, T. R.; Mazaleyrat, F.

    2018-05-01

    We report the role played by cation distribution in determining magnetic properties by comparing dry gel, thermally annealed Ni ferrite prepared by sol-gel auto-combustion technique. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Mössbauer spectroscopy were used to characterize the samples. Both XRD and Mössbauer measurements validate the formation of spinel phase with grain diameter 39.13-45.53 nm. First time antistructural modeling for Ni ferrite is reported to get information on active surface centers. Decrease of Debye temperature θD in annealed sample shows enhancement of lattice vibrations. With thermal annealing experimental and Néel magnetic moment (nBe, nBN) increases, suggesting migration of Ni2+ from B to A site with concurrent migration of Fe3+ from A to B site (non-equilibrium cationic distribution), affecting magnetic properties.

  7. A computational study of anion-modulated cation-π interactions.

    Science.gov (United States)

    Carrazana-García, Jorge A; Rodríguez-Otero, Jesús; Cabaleiro-Lago, Enrique M

    2012-05-24

    The interaction of anions with cationcomplexes formed by the guanidinium cation and benzene was thoroughly studied by means of computational methods. Potential energy surface scans were performed in order to evaluate the effect of the anion coming closer to the cation-π pair. Several structures of guanidinium-benzene complexes and anion approaching directions were examined. Supermolecule calculations were performed on ternary complexes formed by guanidinium, benzene, and one anion and the interaction energy was decomposed into its different two- and three-body contributions. The interaction energies were further dissected into their electrostatic, exchange, repulsion, polarization and dispersion contributions by means of local molecular orbital energy decomposition analysis. The results confirm that, besides the electrostatic cation-anion attraction, the effect of the anion over the cation-π interaction is mainly due to polarization and can be rationalized following the changes in the anion-π and the nonadditive (three-body) terms of the interaction. When the cation and the anion are on the same side of the π system, the three-body interaction is anticooperative, but when the anion and the cation are on opposite sides of the π system, the three-body interaction is cooperative. As far as we know, this is the first study where this kind of analysis is carried out with a structured cation as guanidinium with a significant biological interest.

  8. DNA binding and biological activity of mixed ligand complexes of Cu(II, Ni(II and Co(II with quinolones and N donor ligand

    Directory of Open Access Journals (Sweden)

    S.M M Akram

    2015-10-01

    Full Text Available  AbstractMixed ligand complexes of  Cu(II, Ni(II and Co(II have been synthesized by using levofloxacin and bipyridyl and characterized using spectral and analytical techniques. The binding behavior of the Ni(II and Cu(II complexes with herring sperm DNA(Hs-DNA were determined using electronic absorption titration, viscometric measurements and cyclic voltammetry measurements. The binding constant calculated  for Cu(II and Ni(II complexes are 2.0 x 104 and 4.0 x 104 M-1 respectively. Detailed analysis reveals that these metal complexes interact with DNA through intercalative binding mode. The nuclease activity of  Cu(II and Ni(II complexes with ct-DNA was carried out using agarose gel electrophoresis technique. The antioxidant activities for the synthesized complexes have been tested and the antibacterial activity for Ni(II complex was also checked.Key words: Intercalation, hypochromism, red shift and  peak potential.

  9. Thermodynamic Modeling of Poorly Complexing Metals in Concentrated Electrolyte Solutions: An X-Ray Absorption and UV-Vis Spectroscopic Study of Ni(II) in the NiCl2-MgCl2-H2O System

    Science.gov (United States)

    Zhang, Ning; Brugger, Joël; Etschmann, Barbara; Ngothai, Yung; Zeng, Dewen

    2015-01-01

    Knowledge of the structure and speciation of aqueous Ni(II)-chloride complexes is important for understanding Ni behavior in hydrometallurgical extraction. The effect of concentration on the first-shell structure of Ni(II) in aqueous NiCl2 and NiCl2-MgCl2 solutions was investigated by Ni K edge X-ray absorption (XAS) and UV-Vis spectroscopy at ambient conditions. Both techniques show that no large structural change (e.g., transition from octahedral to tetrahedral-like configuration) occurs. Both methods confirm that the Ni(II) aqua ion (with six coordinated water molecules at R Ni-O = 2.07(2) Å) is the dominant species over the whole NiCl2 concentration range. However, XANES, EXAFS and UV-Vis data show subtle changes at high salinity (> 2 mol∙kg-1 NiCl2), which are consistent with the formation of small amounts of the NiCl+ complex (up to 0.44(23) Cl at a Ni-Cl distance of 2.35(2) Å in 5.05 mol∙kg-1 NiCl2) in the pure NiCl2 solutions. At high Cl:Ni ratio in the NiCl2-MgCl2-H2O solutions, small amounts of [NiCl2]0 are also present. We developed a speciation-based mixed-solvent electrolyte (MSE) model to describe activity-composition relationships in NiCl2-MgCl2-H2O solutions, and at the same time predict Ni(II) speciation that is consistent with our XAS and UV-Vis data and with existing literature data up to the solubility limit, resolving a long-standing uncertainty about the role of chloride complexing in this system. PMID:25885410

  10. Synthesis and Spectral Studies of Ni(II Dithiocarbamate Complexes and Their Use as Precursors for Nickel Sulphides Nanocrystals

    Directory of Open Access Journals (Sweden)

    Azile Nqombolo

    2016-01-01

    Full Text Available Ni(II dithiocarbamate complexes have been synthesized and characterized by UV-Vis, FTIR, and NMR spectroscopic techniques. Electronic spectra measurements indicate that the complexes are four-coordinate square planar geometry while the FTIR confirmed that the dithiocarbamates act as bidentate chelating ligands. The compounds were used as single source precursors and thermolysed at 220°C to prepare HDA-capped NiS nanocrystals which were characterized by absorption and photoluminescence (PL spectra measurements, powder X-ray diffraction (PXRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, and energy dispersive spectroscopy (EDS. Absorption spectra studies showed that the synthesized NiS nanoparticles are blue-shifted relative to the bulk material and PL studies showed emission maxima that are red-shifted compared to the absorption band edges. The XRD patterns of the as-prepared NiS nanoparticles revealed cubic crystalline phases. TEM images showed spherical and close-to-spherical nanocrystals with the size in the range 12–38 nm for NiS1, 8–11 nm for NiS2, and 9–16 nm for NiS3. SEM images showed homogeneous surface morphology and EDS confirmed the presence of Ni and S and the formation of NiS nanoparticles.

  11. Experimental and theoretical study on the complexation of the thallium cation with dibenzo-18-crown-6

    Czech Academy of Sciences Publication Activity Database

    Makrlík, E.; Toman, Petr; Vaňura, P.

    2012-01-01

    Roč. 59, č. 1 (2012), s. 199-202 ISSN 1318-0207 R&D Projects: GA ČR(CZ) GAP205/10/2280 Institutional research plan: CEZ:AV0Z40500505 Keywords : thallium cation * dibenzo-18-crown-6 * complexation, Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.135, year: 2012 http://acta.chem-soc.si/59/59-1-199.pdf

  12. Effect of anthropogenic organic complexants on the solubility of Ni, Th, U(IV) and U(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Felipe-Sotelo, M., E-mail: m.felipe-sotelo@lboro.ac.uk [Department of Chemistry, Loughborough University, LE11 3TU Loughborough, Leicestershire (United Kingdom); Edgar, M. [Department of Chemistry, Loughborough University, LE11 3TU Loughborough, Leicestershire (United Kingdom); Beattie, T. [MCM Consulting. Täfernstrasse 11, CH 5405 Baden-Dättwil (Switzerland); Warwick, P. [Enviras Ltd., LE11 3TU Loughborough, Leicestershire (United Kingdom); Evans, N.D.M.; Read, D. [Department of Chemistry, Loughborough University, LE11 3TU Loughborough, Leicestershire (United Kingdom)

    2015-12-30

    Highlights: • Citrate increases the solubility of Ni, Th and U between 3 and 4 orders of magnitude. • Theophrastite is the solubility controlling phase of Ni in 95%-saturated Ca(OH){sub 2}. • U(VI) and Ni may form Metal-citrate-OH complexes stabilised by the presence of Ca{sup 2+}. - Abstract: The influence of anthropogenic organic complexants (citrate, EDTA and DTPA from 0.005 to 0.1 M) on the solubility of nickel(II), thorium(IV) and uranium (U(IV) and U(VI)) has been studied. Experiments were carried out in 95%-saturated Ca(OH){sub 2} solutions, representing the high pH conditions anticipated in the near field of a cementitious intermediate level radioactive waste repository. Results showed that Ni(II) solubility increased by 2–4 orders of magnitude in the presence of EDTA and DTPA and from 3 to 4 orders of magnitude in the case of citrate. Citrate had the greatest effect on the solubility of Th(IV) and U(IV)/(VI). XRD and SEM analyses indicate that the precipitates are largely amorphous; only in the case of Ni(II), is there some evidence of incipient crystallinity, in the form of Ni(OH){sub 2} (theophrastite). A study of the effect of calcium suggests that U(VI) and Ni(II) may form metal-citrate-OH complexes stabilised by Ca{sup 2+}. Thermodynamic modelling underestimates the concentrations in solution in the presence of the ligands for all the elements considered here. Further investigation of the behaviour of organic ligands under hyperalkaline conditions is important because of the use of the thermodynamic constants in preparing the safety case for the geological disposal of radioactive wastes.

  13. Reducible cationic lipids for gene transfer.

    Science.gov (United States)

    Wetzer, B; Byk, G; Frederic, M; Airiau, M; Blanche, F; Pitard, B; Scherman, D

    2001-01-01

    One of the main challenges of gene therapy remains the increase of gene delivery into eukaryotic cells. We tested whether intracellular DNA release, an essential step for gene transfer, could be facilitated by using reducible cationic DNA-delivery vectors. For this purpose, plasmid DNA was complexed with cationic lipids bearing a disulphide bond. This reduction-sensitive linker is expected to be reduced and cleaved in the reducing milieu of the cytoplasm, thus potentially improving DNA release and consequently transfection. The DNA--disulphide-lipid complexation was monitored by ethidium bromide exclusion, and the size of complexes was determined by dynamic light scattering. It was found that the reduction kinetics of disulphide groups in DNA--lipid complexes depended on the position of the disulphide linker within the lipid molecule. Furthermore, the internal structure of DNA--lipid particles was examined by small-angle X-ray scattering before and after lipid reduction. DNA release from lipid complexes was observed after the reduction of disulphide bonds of several lipids. Cell-transfection experiments suggested that complexes formed with selected reducible lipids resulted in up to 1000-fold higher reporter-gene activity, when compared with their analogues without disulphide bonds. In conclusion, reduction-sensitive groups introduced into cationic lipid backbones potentially allow enhanced DNA release from DNA--lipid complexes after intracellular reduction and represent a tool for improved vectorization. PMID:11389682

  14. Simulations on Nickel target preparation and separation of Ni(II)-Cu(II) matrix for production of radioisotope "6"4Cu

    International Nuclear Information System (INIS)

    Sunarhadijoso Soenarjo; Wira Y Rahman; Sriyono; Triyanto

    2011-01-01

    The simulations on Nickel target preparation and separation of Ni(II)-Cu(II) matrix has been carried out as a preliminary study for production of medical radioisotope Cu-64 based on nuclear reaction of "6"4Ni (p,n) "6"4Cu. The nickel target preparation was performed by means of electroplating method using acidic solution of nickel chloride - boric acid mixture and basic solution of nickel sulphate - nickel chloride mixture on a silver - surfaced-target holder. The simulated solution of Ni(II) - Cu(II) matrix was considered as the solution of post-proton-irradiated nickel target containing both irradiated nickel and radioactive copper, but in the presented work the proton irradiation of nickel target was omitted, while the radioactive copper was originally obtained from neutron irradiation of CuO target. The separation of radioactive copper from the nickel target matrix was based on anion exchange column chromatography in which the radiocopper was conditioned to form anion complex CuCl_4"2"- and retained on the column while the nickel was kept in the form of Ni"2"+ cation and eluted off from the column. The retained radioactive copper was then eluted out the column in the condition of dilute HCl changing back the copper anion complex into Cu"2"+ cation. It was found that the electroplating result from the acidic solution was more satisfied than that from the basic solution. By conditioning the matrix solution at HCl 6 M, the radioactive copper was found in the forms of Cu"2"+ and CuCl_4"2"- while the nickel was totally in the form of Ni"2"+. In the condition of HCl 9 M, the radioactive copper was mostly in the form of CuCl_4"2"- while the nickel was found as both Ni"2"+ and NiCl_4"2"-. The best condition of separation was in HCl 8 M in which the radioactive copper was mostly in the form of CuCl_4"2"- while the nickel was mostly in the form of Ni"2"+. The retained CuCl_4"2"- was then changed back into Cu_2_+ cation form and eluted out the column by using HCl 0.05 M

  15. Use of Electro-spray Ionization Mass Spectrometry (ESI-MS) for the characterization of complexes 'ligand - metallic cations' in solution

    Energy Technology Data Exchange (ETDEWEB)

    Berthon, Laurence; Zorz, Nicole; Lagrave, Stephanie; Gannaz, Benoit; Hill, Clement [CEA-Marcoule DEN-DRCP-SCPS-LCSE, BP 17171, 30207 Bagnols sur Ceze cedex (France)

    2008-07-01

    In the framework of nuclear waste reprocessing, separation processes of minor actinides from fission products are developed by Cea. In order to understand the mechanisms involved in the extraction processes, the 'ligand/metallic cation' complexes, formed in the organic phases are characterized by electro-spray-mass-spectrometry (ESI-MS). This paper deals with the extraction of lanthanides (III) and americium (III) cations by an organic phase composed of a malonamide or / and a dialkyl phosphoric acid, diluted in an aliphatic diluent. For the dialkyl phosphoric acid, Ln(DEHP){sub 3}(HDEHP){sub 3} complexes are observed and in the presence of a large excess of Ln(NO{sub 3}){sub 3}, dinuclear species are also observed. For the malonamide extractant, it appears that the complexes formed in the organic phase are of the Nd(NO{sub 3}){sub 3}D{sub x} type, with 2 {<=} x {<=} 4: their distributions depend on the ratio [Ln]/[DMDOHEMA]. When the two extractants are present in the organic phase, mixed 'Ln-malonamide-dialkyl phosphoric acid' species are observed. The influence of several parameters, such as extractant concentration, solute concentration, aqueous acidity and the nature of the cations (lanthanides or americium) are studied. (authors)

  16. EXAFS analysis of cations distribution in structure of Co_1_−_xNi_xFe_2O_4 nanoparticles obtained by hydrothermal method in aloe vera extract solution

    International Nuclear Information System (INIS)

    Wongpratat, Unchista; Maensiri, Santi; Swatsitang, Ekaphan

    2016-01-01

    Graphical abstract: It is obvious from the M–H curves at room temperature of Co_1_−_xNi_xFe_2O_4 (x = 0, 0.25, 0.50, 0.75 and 1.0) nanoparticles that partially substitution of the lower Bohr magneton (2 μ_B) and smaller atomic radii (0.55 Å at A site, 0.69 Å at B site) of Ni"2"+ ions on the higher Bohr magneton (3 μ_B) and larger atomic radii (0.58 Å at A site, 0.74 Å at B site) of Co"2"+ ions can increase the saturation magnetization (M_s) of sample with x = 0.75 to approximately 1.4 times of sample with x = 0, due to the increase of the aspect ratio (surface to volume) of nanoparticles, as a result of particle size decreasing from 37.03 to 12.63 nm. In addition to this, the ferrimagnetic behavior of CoFe_2O_4 has been changed to superparamagnetic behavior with the dramatic decrease of the coercivity from 1365.60 to 63.15 Oe. - Highlights: • Magnetic behavior of Co_1_−_xNi_xFe_2O_4 NPs depends on Ni content and size of NPs. • Distribution of Co"2"+ and Ni"2"+ ions in the structure results in the increase of M_s. • Superparamagnetic behavior is observed with increasing of the aspect ratio. • M_s is increased by a factor 1.4 to a value of 57.57 emu/g in Co_0_._2_5Ni_0_._7_5Fe_2O_4. • H_c is decreased by a factor 20 to a value of 63.15 Oe in Co_0_._2_5Ni_0_._7_5Fe_2O_4. - Abstract: Effect of cations distribution upon EXAFS analysis on magnetic properties of Co_1_−_xNi_xFe_2O_4 (x = 0, 0.25, 0.50, 0.75 and 1.0) nanoparticles prepared by the hydrothermal method in aloe vera extract solution were studied. XRD analysis confirmed a pure phase of cubic spinel ferrite of all samples. Changes in lattice parameter and particle size depended on the Ni content with partial substitution and site distributions of Co"2"+, Ni"2"+ ions of different ionic radii at both tetrahedral and octahedral sites in the crystal structure. Particle sizes of samples estimated by TEM images were found to be in the range of 10.87–62.50 nm. The VSM results at room

  17. Structural evolution of the double perovskites Sr{sub 2}B'UO{sub 6} (B' = Mn, Fe, Co, Ni, Zn) upon reduction: Magnetic behavior of the uranium cations

    Energy Technology Data Exchange (ETDEWEB)

    Pinacca, R.M., E-mail: rmp@unsl.edu.ar [Area de Quimica General e Inorganica ' Dr. Gabino F. Puelles' , Departamento de Quimica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina); Viola, M.C.; Pedregosa, J.C. [Area de Quimica General e Inorganica ' Dr. Gabino F. Puelles' , Departamento de Quimica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis (Argentina); Carbonio, R.E. [INFIQC (CONICET), Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, X5000HUA Cordoba (Argentina); Lope, M.J. Martinez; Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, 28049 Madrid (Spain)

    2011-11-15

    Highlights: {yields} Evolution of the double perovskites Sr{sub 2}B'UO{sub 6} upon reduction were studied by XRPD. {yields} Orthorhombic (Pnma) disordered perovskites SrB'{sub 0.5-x}U{sub 0.5+x}O{sub 3} were obtained at 900 {sup o}C. {yields} U{sup 5+/4+} and Zn{sup 2+} cations are distributed at random over the octahedral positions. {yields} AFM ordering for the perovskite with B' = Zn appears below 30 K. -- Abstract: We describe the preparation of five perovskite oxides obtained upon reduction of Sr{sub 2}B'UO{sub 6} (B' = Mn, Fe, Co, Ni, Zn) with H{sub 2}/N{sub 2} (5%/95%) at 900 {sup o}C during 8 h, and their structural characterization by X-ray powder diffraction (XRPD). During the reduction process there is a partial segregation of the elemental metal when B' = Co, Ni, Fe, and the corresponding B'O oxide when B' = Mn, Zn. Whereas the parent, oxygen stoichiometric double perovskites Sr{sub 2}B'UO{sub 6} are long-range ordered concerning B' and U cations. The crystal structures of the reduced phases, SrB'{sub 0.5-x}U{sub 0.5+x}O{sub 3} with 0.37 < x < 0.27, correspond to simple, disordered perovskites; they are orthorhombic, space group Pnma (No. 62), with a full cationic disorder at the B site. Magnetic measurements performed on the phase with B' = Zn, indicate uncompensated antiferromagnetic ordering of the U{sup 5+}/U{sup 4+} sublattice below 30 K.

  18. Cationic liposome/DNA complexes: from structure to interactions with cellular membranes.

    Science.gov (United States)

    Caracciolo, Giulio; Amenitsch, Heinz

    2012-10-01

    Gene-based therapeutic approaches are based upon the concept that, if a disease is caused by a mutation in a gene, then adding back the wild-type gene should restore regular function and attenuate the disease phenotype. To deliver the gene of interest, both viral and nonviral vectors are used. Viruses are efficient, but their application is impeded by detrimental side-effects. Among nonviral vectors, cationic liposomes are the most promising candidates for gene delivery. They form stable complexes with polyanionic DNA (lipoplexes). Despite several advantages over viral vectors, the transfection efficiency (TE) of lipoplexes is too low compared with those of engineered viral vectors. This is due to lack of knowledge about the interactions between complexes and cellular components. Rational design of efficient lipoplexes therefore requires deeper comprehension of the interactions between the vector and the DNA as well as the cellular pathways and mechanisms involved. The importance of the lipoplex structure in biological function is revealed in the application of synchrotron small-angle X-ray scattering in combination with functional TE measurements. According to current understanding, the structure of lipoplexes can change upon interaction with cellular membranes and such changes affect the delivery efficiency. Recently, a correlation between the mechanism of gene release from complexes, the structure, and the physical and chemical parameters of the complexes has been established. Studies aimed at correlating structure and activity of lipoplexes are reviewed herein. This is a fundamental step towards rational design of highly efficient lipid gene vectors.

  19. Cation radicals of xanthophylls.

    Science.gov (United States)

    Galinato, Mary Grace I; Niedzwiedzki, Dariusz; Deal, Cailin; Birge, Robert R; Frank, Harry A

    2007-10-01

    Carotenes and xanthophylls are well known to act as electron donors in redox processes. This ability is thought to be associated with the inhibition of oxidative reactions in reaction centers and light-harvesting pigment-protein complexes of photosystem II (PSII). In this work, cation radicals of neoxanthin, violaxanthin, lutein, zeaxanthin, beta-cryptoxanthin, beta-carotene, and lycopene were generated in solution using ferric chloride as an oxidant and then studied by absorption spectroscopy. The investigation provides a view toward understanding the molecular features that determine the spectral properties of cation radicals of carotenoids. The absorption spectral data reveal a shift to longer wavelength with increasing pi-chain length. However, zeaxanthin and beta-cryptoxanthin exhibit cation radical spectra blue-shifted compared to that of beta-carotene, despite all of these molecules having 11 conjugated carbon-carbon double bonds. CIS molecular orbital theory quantum computations interpret this effect as due to the hydroxyl groups in the terminal rings selectively stabilizing the highest occupied molecular orbitals of preferentially populated s-trans-isomers. The data are expected to be useful in the analysis of spectral results from PSII pigment-protein complexes seeking to understand the role of carotene and xanthophyll cation radicals in regulating excited state energy flow, in protecting PSII reaction centers against photoinhibition, and in dissipating excess light energy absorbed by photosynthetic organisms but not used for photosynthesis.

  20. Cationic dyes as extraction and spectrophotometric reagents: extraction of thiocyanate complex of mercury (II) in association with malachite green

    Energy Technology Data Exchange (ETDEWEB)

    Iyer, N V; Murthy, T K.S.

    1975-01-01

    An extraction spectrophotometric method for the determination of Hg(II) is described. This is based on the extraction of Hg(CNS)/sub 3//sup -/ complex in association with the cation of malachite green into benzene. The benzene extract has lambda max at 640 mm. Maximal extraction takes place from an aqueous solution of pH 4.5. Although four extractions are needed for quantitative recovery of Hg(II), a single extraction with aqueous organic = 2.5 : 1 is recommended for analysis and the apparent molar absorptivity is 65,000. The interference from a number of anions and cations has also been studied. (auth)

  1. Naked (C5Me5)(2)M cations (M = Sc, Ti, and V) and their fluoroarene complexes

    NARCIS (Netherlands)

    Bouwkamp, MW; Budzelaar, PHM; Gercama, J; Morales, ID; de Wolf, J; Meetsma, A; Troyanov, SI; Teuben, JH; Hessen, B; Budzelaar, Peter H.M.; Hierro Morales, Isabel Del; Troyanov, Sergei I.

    2005-01-01

    The ionic metallocene complexes [Cp*M-2][BPh4] (CP* = C5Me5) of the trivalent 3d metals Sc, Ti, and V were synthesized and structurally characterized. For M Sc, the anion interacts weakly with the metal center through one of the phenyl groups, but for M = Ti and V, the cations are naked. They each

  2. Interaction of a Ni(II) tetraazaannulene complex with elongated fullerenes as simple models for carbon nanotubes.

    Science.gov (United States)

    Henao-Holguín, Laura Verónica; Basiuk, Vladimir A

    2015-06-01

    Nickel(II) complex of 5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecine (NiTMTAA), which can be employed for noncovalent functionalization of carbon nanotubes (CNTs), represents a more complex and interesting case in terms of structure of the resulting nanohybrids, as compared to the related materials functionalized with porphyrins and phthalocyanines. Due to its saddle shape, the NiTMTAA molecule adsorbed can adopt different, energetically non-equivalent orientations with respect to CNT, depending on whether CH3 or C6H4 groups contact the latter. The main goal of the present work was to provide information on the interactions of NiTMTAA with simple single-walled CNT (SWNT) models accessible for dispersion-corrected DFT calculations. For reasons of comparison, we employed three such functionals: M06-2X and LC-BLYP as implemented in Gaussian 09 package, and PBE-G as implemented in Materials Studio 6.0. In order to roughly estimate the effect of nanotube chirality on the interaction strenght, we considered two short closed-end SWNT models (also referred to as 'elongated fullerenes'), one armchair and one zigzag, derived from C60 and C80 hemispheres. In addition, we calculated similar complexes with C60, as well as I h and D 5h isomers of C80. The results were analyzed in terms of optimized geometries, formation energies, HOMO-LUMO gap energies, and intermolecular separations. Graphical Abstract Interaction of Ni(II) tetraazaannulene complex with elongated fullerenes.

  3. Synthesis, crystallographic and spectral studies of homochiral cobalt(II) and nickel(II) complexes of a new terpyridylaminoacid ligand

    Science.gov (United States)

    Wang, Xing; Gao, Chang-Qing; Gao, Zhi-Yang; Wu, Ben-Lai; Niu, Yun-Yin

    2018-04-01

    Based on a chiral terpyridylaminoacid ligand, a series of homochiral Co(II) and Ni(II) complexes, namely, [Co(H2L)(HL)]·Cl·(PF6)2·2H2O (1), [Ni(H2L)(HL)]·Cl·(PF6)2 (2), [Co2(L)2(CH3OH)(H2O)]·(PF6)2·CH3OH (3), [Ni2(L)2(CH3OH)2]·(PF6)2·2CH3OH (4), [Co2(L)2(N3)2]·3H2O (5), and [Ni2(L)2(SCN)2]·4H2O (6) have been successfully synthesized and characterized by elemental analysis, TGA, spectroscopic methods (IR, CD and electronic absorption spectra) and single-crystal X-ray diffraction structural analysis (HL = (S)-2-((4-([2,2':6‧,2″-terpyridin]-4‧-yl)benzyl)amino)-4-methylpentanoic acid). In the acidic reaction conditions, one protonated (H2L)+ and one zwitterionic HL only used their terpyridyl groups to chelate one metal ion Co(II) or Ni(II), forming chiral mononuclear cationic complexes 1 or 2. But in the basic and hydro(solvo)thermal reaction conditions, deprotonated ligands (L)‒ acting as bridges used their terpyridyl and amino acid groups to link with two Co(II) or Ni(II) ions, fabricating chiral dinuclear metallocyclic complexes 3-6. Those chiral mononuclear and dinuclear complexes whose chirality originates in the homochiral ligand HL further self-assemble into higher-dimensional homochiral supramolecular frameworks through intermolecular hydrogen-bonding and π···π interactions. Notably, the coordination mode, hydrogen-bonding site, and existence form of HL ligand can be controlled by the protonation of its amino group, and the architectural diversity of those supramolecular frameworks is adjusted by pH and counter anions. Very interestingly, the 3D porous supramolecular frameworks built up from the huge chiral mononuclear cationic complexes 1 and 2 have novel helical layers only formed through every right-handed helical chain intertwining with two adjacent same helical chains, and the 2D supramolecular helicate 5 consists of two types of left-handed helical chains.

  4. The magnetic Curie temperature and exchange coupling between cations in tetragonal spinel oxide Mn{sub 2.5}M{sub 0.5}O{sub 4} (M = Co, Ni, Mn, Cr, and Mg) films

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, K.; Cheng, C. W.; Chern, G. [Physics Department and SPIN Research Center, National Chung Cheng University, Chia-Yi, Taiwan, 621 (China)

    2012-04-01

    Mn{sub 3}O{sub 4} is a Jahn-Taller tetragonal ferrite that has a relatively low Curie temperature (T{sub c}) of {approx}43 K due to weak coupling between the canting spins. In this study, we fabricated a series of 100-nm-thick Mn{sub 2.5}M{sub 0.5}O{sub 4} (M = Co, Ni, Mn, Cr, and Mg) films via oxygen-plasma-assisted molecular beam epitaxy and measured the structural and magnetic properties of these films. These films show single phase quality, and the c-axis lattice parameter of pure Mn{sub 3}O{sub 4} is 0.944 nm, with a c/a ratio {approx}1.16, consistent with the bulk values. The replacement of Mn by M (M = Co, Ni, Cr, and Mg) changes the lattice parameters, and the c/a ratio varies between 1.16 and 1.06 depending upon the cation distribution of the films. The magnetic Curie temperatures of these films also vary in the range of 25-66 K in that Ni and Co enhance the T{sub c} whereas Mg reduces the T{sub c} (Cr shows no effect on the T{sub c}). These changes to the T{sub c} are related to both the element electronic state and the cation distributions in these compounds. As a non-collinear spin configuration can induce electrical polarization, the present study provides a systematic way to enhance the magnetic transition temperature in tetragonal spinel ferrites.

  5. Cyanide bridged hetero-metallic polymeric complexes: Syntheses, vibrational spectra, thermal analyses and crystal structures of complexes [M(1,2-dmi)2Ni(μ-CN)4]n (M = Zn(II) and Cd(II))

    Science.gov (United States)

    Kürkçüoğlu, Güneş Süheyla; Sayın, Elvan; Şahin, Onur

    2015-12-01

    Two cyanide bridged hetero-metallic complexes of general formula, [M(1,2-dmi)2Ni(μ-CN)4]n (1,2-dmi = 1,2-dimethylimidazole and M = Zn(II) or Cd(II)) have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal analyses and elemental analyses. The crystallographic analyses reveal that the complexes, [Zn(1,2-dmi)2Ni(μ-CN)4] (1) and [Cd(1,2-dmi)2Ni(μ-CN)4] (2), have polymeric 2D networks. In the complexes, four cyanide groups of [Ni(CN)4]2- coordinated to the adjacent M(II) ions and distorted octahedral geometries of complexes are completed by two nitrogen atoms of trans 1,2-dmi ligands. The structures of 1 and 2 are similar and linked via intermolecular hydrogen bonding, C-H⋯Ni interactions to give rise to 3D networks. Vibration assignments are given for all the observed bands and the spectral features also supported to the crystal structures of heteronuclear complexes. The FT-IR and Raman spectra of the complexes are very much consistent with the structural data presented.

  6. New double-cation borohydrides

    Energy Technology Data Exchange (ETDEWEB)

    Lindemann, Inge; Domenech Ferrer, Roger; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden, Institute for Metallic Materials, P.O. Box 270016, 01171 Dresden (Germany); Filinchuk, Yaroslav [Swiss-Norwegian Beam Lines at ESRF, BP-220, 38043 Grenoble (France); Hagemann, Hans; Cerny, Radovan [Department of Physical Chemistry and Crystallography, University of Geneva, 1211 Geneva (Switzerland)

    2011-07-01

    Complex hydrides are under consideration for on-board hydrogen storage due to their high hydrogen density. However, up to now conventional borohydrides are either too stable or unstable for applications as in PEM fuel cells (60-120 C). Recently, double-cation borohydride systems have attracted great interest. The desorption temperature of the borohydrides decreases with increasing electronegativity of the cation. Consequently, it is possible to tailor a feasible on-board hydrogen storage material by the combination of appropriate cations. The stability was found to be intermediate between the single-cation borohydride systems. Two combinations were sucessfully synthesised by metathesis reaction via high energy ball milling. Al-Li-borohydride shows desorption at about 70 C combined with a very high hydrogen density (17.2 wt.%) and the Na-Al-borohydride (14.2 wt.%) decomposes around 90 C. Both desorption temperatures are in the target range for applications. The decomposition pathways were observed by in-situ-Raman spectroscopy, DSC (Differential Scanning Calorimetry), TG (Thermogravimetry) and thermal desorption measurements.

  7. Interactions of nickel(II) with histones. Stability and solution structure of complexes with CH3CO-Cys-Ala-Ile-His-NH2, a putative metal binding sequence of histone H3.

    Science.gov (United States)

    Bal, W; Lukszo, J; Jezowska-Bojczuk, M; Kasprzak, K S

    1995-01-01

    Nickel(II) compounds are established human carcinogens, but the molecular mechanisms underlying their activity are only partially known. One mechanism may include mediation by nickel of promutagenic oxidative DNA damage that depends on Ni(II) binding to chromatin. To characterize such binding at the histone moiety of chromatin, we synthesized the peptide CH3CO-Cys-Ala-Ile-His-NH2 (L), a model of the evolutionarily conserved motif in histone H3 with expected affinity for transition metals, and evaluated its reactivity toward Ni(II). Combined spectroscopic (UV/vis, CD, NMR) and potentiometric measurements showed that, at physiological pH, mixtures of Ni(II) and L yielded unusual macrochelate complexes, NiL and NiL2, in which the metal cation was bound through Cys and His side chains in a square-planar arrangement. Above pH 9, a NiH-3L complex was formed, structurally analogous to typical square-planar nickel complexes. These complexes are expected to catalyze oxidation reactions, and therefore, coordination of Ni(II) by the L motif in core histone H3 may be a key event in oxidative DNA base damage observed in the process of Ni(II)-induced carcinogenesis.

  8. Disorder and intermolecular interactions in a family of tetranuclear Ni(II) complexes probed by high-frequency electron paramagnetic resonance.

    Science.gov (United States)

    Lawrence, Jon; Yang, En-Che; Edwards, Rachel; Olmstead, Marilyn M; Ramsey, Chris; Dalal, Naresh S; Gantzel, Peter K; Hill, Stephen; Hendrickson, David N

    2008-03-17

    High-frequency electron paramagnetic resonance (HFEPR) data are presented for four closely related tetranuclear Ni(II) complexes, [Ni(hmp)(MeOH)Cl]4.H2O (1a), [Ni(hmp)(MeOH)Br]4.H2O (1b), [Ni(hmp)(EtOH)Cl]4.H2O (2), and [Ni(hmp)(dmb)Cl]4 (3) (where hmp(-) is the anion of 2-hydroxymethylpyridine and dmb is 3,3'-dimethyl-1-butanol), which exhibit magnetic bistability (hysteresis) and fast magnetization tunneling at low temperatures, properties which suggest they are single-molecule magnets (SMMs). The HFEPR spectra confirm spin S = 4 ground states and dominant uniaxial anisotropy (DSz(2), D SMM. The individual fine structure peaks (due to zero-field splitting) for complexes 1a, 1b, and 2 are rather broad. They also exhibit further (significant) splitting, which can be explained by the fact that there exists two crystallographically distinct Ni 4 sites in the lattices for these complexes, with associated differences in metal-ligand bond lengths and different zero-field splitting (ZFS) parameters. The broad EPR lines, meanwhile, may be attributed to ligand and solvent disorder, which results in additional distributions of microenvironments. In the case of complex 3, there are no solvate molecules in the structure, and only one distinct Ni 4 molecule in the lattice. Consequently, the HFEPR data for complex 3 are extremely sharp. As the temperature of a crystal of complex 3 is decreased, the HFEPR spectrum splits abruptly at approximately 46 K into two patterns with very slightly different ZFS parameters. Heat capacity data suggest that this is caused by a structural transition at 46.6 K. A single-crystal X-ray structure at 12(2) K indicates large thermal parameters on the terminal methyl groups of the dmb (3,3-dimethyl-1-butanol) ligand. Most likely there exists dynamic disorder of parts of the dmb ligand above 46.6 K; an order-disorder structural phase transition at 46.6 K then removes some of the motion. A further decrease in temperature (<6 K) leads to further fine

  9. Gas-phase noncovalent functionalization of carbon nanotubes with a Ni(II) tetraaza[14]annulene complex

    Science.gov (United States)

    Basiuk, Vladimir A.; Henao-Holguín, Laura Verónica; Álvarez-Zauco, Edgar; Bassiouk, María; Basiuk, Elena V.

    2013-04-01

    The noncovalent functionalization of carbon nanotubes (CNTs) with aromatic polyazamacrocyclic compounds, based on π-π-interactions, keeps the intrinsic electronic structure of CNTs totally intact and allows for combining unique properties of the two interacting components. In addition to porphyrins and phthalocyanines, there are other, simpler compounds exhibiting similar properties, potentially useful for photovoltaic, catalytic and electrochemical applications: for example, tetraaza[14]annulenes. Many of them are highly thermally stable, which makes it possible to employ physical vapor deposition for the preparation of macrocycle-nanotube hybrids. One of such compounds is Ni(II) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12,14-hexaene (also called Ni(II)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA for simplicity). In the present work, we attempted the noncovalent functionalization of both single-walled and multi-walled CNTs with NiTMTAA in the gas phase at two selected temperatures of 220 and 270 °C, which does not require the use of organic solvents and therefore can be considered as ecologically friendly. The nanohybrids obtained were characterized by means of scanning and transmission electron microscopy, energy dispersive X-ray, Fourier-transform infrared and Raman spectroscopy, as well as thermogravimetric analysis. An additional insight into the structure of adsorption complexes of NiTMTAA on CNTs was provided from density functional theory and molecular mechanics calculations.

  10. Gas-phase noncovalent functionalization of carbon nanotubes with a Ni(II) tetraaza[14]annulene complex

    Energy Technology Data Exchange (ETDEWEB)

    Basiuk, Vladimir A., E-mail: basiuk@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico); Henao-Holguín, Laura Verónica [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico); Álvarez-Zauco, Edgar [Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito Exterior C.U., 04510, México D.F. (Mexico); Bassiouk, María [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico); Basiuk, Elena V. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, México D.F. (Mexico)

    2013-04-01

    The noncovalent functionalization of carbon nanotubes (CNTs) with aromatic polyazamacrocyclic compounds, based on π–π-interactions, keeps the intrinsic electronic structure of CNTs totally intact and allows for combining unique properties of the two interacting components. In addition to porphyrins and phthalocyanines, there are other, simpler compounds exhibiting similar properties, potentially useful for photovoltaic, catalytic and electrochemical applications: for example, tetraaza[14]annulenes. Many of them are highly thermally stable, which makes it possible to employ physical vapor deposition for the preparation of macrocycle–nanotube hybrids. One of such compounds is Ni(II) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12, 14-hexaene (also called Ni(II)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA for simplicity). In the present work, we attempted the noncovalent functionalization of both single-walled and multi-walled CNTs with NiTMTAA in the gas phase at two selected temperatures of 220 and 270 °C, which does not require the use of organic solvents and therefore can be considered as ecologically friendly. The nanohybrids obtained were characterized by means of scanning and transmission electron microscopy, energy dispersive X-ray, Fourier-transform infrared and Raman spectroscopy, as well as thermogravimetric analysis. An additional insight into the structure of adsorption complexes of NiTMTAA on CNTs was provided from density functional theory and molecular mechanics calculations.

  11. Gas-phase noncovalent functionalization of carbon nanotubes with a Ni(II) tetraaza[14]annulene complex

    International Nuclear Information System (INIS)

    Basiuk, Vladimir A.; Henao-Holguín, Laura Verónica; Álvarez-Zauco, Edgar; Bassiouk, María; Basiuk, Elena V.

    2013-01-01

    The noncovalent functionalization of carbon nanotubes (CNTs) with aromatic polyazamacrocyclic compounds, based on π–π-interactions, keeps the intrinsic electronic structure of CNTs totally intact and allows for combining unique properties of the two interacting components. In addition to porphyrins and phthalocyanines, there are other, simpler compounds exhibiting similar properties, potentially useful for photovoltaic, catalytic and electrochemical applications: for example, tetraaza[14]annulenes. Many of them are highly thermally stable, which makes it possible to employ physical vapor deposition for the preparation of macrocycle–nanotube hybrids. One of such compounds is Ni(II) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12, 14-hexaene (also called Ni(II)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA for simplicity). In the present work, we attempted the noncovalent functionalization of both single-walled and multi-walled CNTs with NiTMTAA in the gas phase at two selected temperatures of 220 and 270 °C, which does not require the use of organic solvents and therefore can be considered as ecologically friendly. The nanohybrids obtained were characterized by means of scanning and transmission electron microscopy, energy dispersive X-ray, Fourier-transform infrared and Raman spectroscopy, as well as thermogravimetric analysis. An additional insight into the structure of adsorption complexes of NiTMTAA on CNTs was provided from density functional theory and molecular mechanics calculations.

  12. Molecular dynamics simulations of ter-pyridine and bis-triazinyl-pyridine complexes with lanthanide cations; Etude de dynamique moleculaire de complexes de la bis-triazinyl-pyridine (BTP) et de la terpyridine avec des lanthanides(3)

    Energy Technology Data Exchange (ETDEWEB)

    Guilbaud, Ph. [CEA Valrho, (DCC/DRRV/SEMP), 30 - Marcoule (France)

    2000-07-01

    The search for ligands which specifically separate actinides(III) from lanthanides(III) by liquid-liquid extraction has prompted considerable research in the Process Design and Modeling Department ('Service d'Etude et de Modelisation des Procedes'- SEMP). Ligands with soft donor atoms AS) that are able to perform this separation have already been investigated and research is currently under way to improve their performance for high acidic feeds. Theoretical chemistry research is conducted in the Theoretical and Structural Chemistry Laboratory ('Laboratoire de Chimie Theorique et Structurale') to improve our understanding of the complexation and extraction of these cations with such ligands. Theoretical studies were first carried out for the ter-pyridine (TPY) and bis-triazinyl-pyridine (BTP) ligands that display fairly good ability to separate and extract actinide(III) from lanthanide(III) ions. Molecular dynamics simulations were performed on ter-pyridine and bis-triazinyl-pyridine complexes with three lanthanide cations (La{sup 3+}, Eu{sup 3+} and Lu{sup 3+}) for vacuum and for water solutions. These calculations were carried out without counter-ions, with three nitrate (NO{sub 3}{sup -}) ions, and, in the case of ter-pyridine, with three {alpha}-bromo-caprate anions that are likely to be used experimentally as synergistic agents for the separation and extraction of An(III) from Ln(III). Molecular dynamics simulations were first performed for vacuum to evaluate the distances between nitrogen and lanthanide atoms (Ln{sup 3+},N) and intrinsic interaction energies to poly-nitrogenous ligands with or without NO{sub 3} ions, and for both ligands. The (Ln{sup 3+},N) distances decrease and the cation/ligand interaction energies increase along the La{sup 3+}, Eu{sup 3+}, Lu{sup 3+} series, with decreasing Ln(III) ion radii. The introduction of nitrate counter-ions makes the (Ln{sup 3+},N) distances slightly higher, and the TPY/Ln{sup 3+} and BTP

  13. Liquid-solid extraction of cationic metals by cationic amphiphiles

    International Nuclear Information System (INIS)

    Muller, W.

    2010-01-01

    In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl - , NO 3 - , C 2 O 4 2- ) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu 2+ , Zn 2+ , UO 2 2+ , Fe 3+ , Nd 3+ , Eu 3+ , Th 4+ ) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author) [fr

  14. Structure of the oxalate-ATP complex with pyruvate kinase: ATP as a bridging ligand for the two divalent cations

    International Nuclear Information System (INIS)

    Lodato, D.T.; Reed, G.H.

    1987-01-01

    The 2 equiv of divalent cation that are required cofactors for pyruvate kinase reside in sites of different affinities for different species of cation. The intrinsic selectivity of the protein-based site for Mn(II) and of the nucleotide-based site for Mg(II) has been exploited in electron paramagnetic resonance (EOR) investigations of ligands for Mn(II) at the protein-based site. Oxalate, a structural analogue of the enolate of pyruvate, has been used as a surrogate for the reactive form of pyruvate in complexes with enzyme, Mn(II), Mg(II), and ATP. Superhyperfine coupling between the unpaired electron spin of Mn(II) and the nuclear spin of 17 O, specifically incorporated into oxalate, shows that oxalate is bound at the active site as a bidentate chelate with Mn(II). Coordination of the γ-phosphate of ATP to this same Mn(II) center is revealed by observation of superhyperfine coupling from 17 O regiospecifically incorporated into the γ-phosphate group of ATP. By contrast, 17 O in the α-phosphate or in the β-phosphate groups of ATP does not influence the spectrum. Experiments in 17 O-enriched water show that there is also a single water ligand bound to the Mn(II). These data indicate that ATP bridges Mn(II) and Mg(II) at the active site. A close spacing of the two divalent cations is also evident from the occurrence of magnetic interactions for complexes in which 2 equiv of Mn(II) are present at the active site. The structure for the enzyme-Mn(II)-oxalate-Mg(II)-ATP complex suggests a scheme for the normal reverse reaction of pyruvate kinase in which the divalent cation at the protein-based site activates the keto acid substrate through chelation and promotes phospho transfer by simultaneous coordination to the enolate oxygen and to a pendant oxygen from the γ-phosphate of ATP

  15. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism.

    Science.gov (United States)

    Boughlala, Zakaria; Fonseca Guerra, Célia; Bickelhaupt, F Matthias

    2016-06-01

    We have analyzed the structure and bonding of gas-phase Cl-X and [HCl-X](+) complexes for X(+)= H(+), CH3 (+), Li(+), and Na(+), using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl(-) and HCl for the various cations. The Cl-X bond becomes longer and weaker along X(+) = H(+), CH3 (+), Li(+), and Na(+). Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn-Sham molecular orbital (KS-MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities.

  16. Minority anion substitution by Ni in ZnO

    CERN Document Server

    Pereira, Lino Miguel da Costa; Correia, João Guilherme; Amorim, Lígia Marina; Silva, Daniel José; David-Bosne, Eric; Decoster, Stefan; da Silva, Manuel Ribeiro; Temst, Kristiaan; Vantomme, André

    2013-01-01

    We report on the lattice location of implanted Ni in ZnO using the $\\beta$− emission channeling technique. In addition to the majority substituting for the cation (Zn), a significant fraction of the Ni atoms occupy anion (O) sites. Since Ni is chemically more similar to Zn than it is to O, the observed O substitution is rather puzzling. We discuss these findings with respect to the general understanding of lattice location of dopants in compound semiconductors. In particular, we discuss potential implications on the magnetic behavior of transition metal doped dilute magnetic semiconductors.

  17. The effect of specific solvent-solute interactions on complexation of alkali-metal cations by a lower-rim calix[4]arene amide derivative.

    Science.gov (United States)

    Horvat, Gordan; Stilinović, Vladimir; Kaitner, Branko; Frkanec, Leo; Tomišić, Vladislav

    2013-11-04

    Complexation of alkali-metal cations with calix[4]arene secondary-amide derivative, 5,11,17,23-tetra(tert-butyl)-25,26,27,28-tetra(N-hexylcarbamoylmethoxy)calix[4]arene (L), in benzonitrile (PhCN) and methanol (MeOH) was studied by means of microcalorimetry, UV and NMR spectroscopies, and in the solid state by X-ray crystallography. The inclusion of solvent molecules (including acetonitrile, MeCN) in the calixarene hydrophobic cavity was also investigated. The classical molecular dynamics (MD) simulations of the systems studied were carried out. By combining the results obtained using the mentioned experimental and computational techniques, an attempt was made to get an as detailed insight into the complexation reactions as possible. The thermodynamic parameters, that is, equilibrium constants, reaction Gibbs energies, enthalpies, and entropies, of the investigated processes were determined and discussed. The stability constants of the 1:1 (metal:ligand) complexes measured by different methods were in very good agreement. Solution Gibbs energies of the ligand and its complexes with Na(+) and K(+) in methanol and acetonitrile were determined. It was established that from the thermodynamic point of view, apart from cation solvation, the most important reason for the huge difference in the stability of these complexes in the two solvents lay in the fact that the transfer of complex species from MeOH to MeCN was quite favorable. That could be at least partly explained by a more exergonic inclusion of the solvent molecule in the complexed calixarene cone in MeCN as compared to MeOH, which was supported by MD simulations. Molecular and crystal structures of the lithium cation complex of L with the benzonitrile molecule bound in the hydrophobic calixarene cavity were determined by single-crystal X-ray diffraction. As far as we are aware, for the first time the alkali-metal cation was found to be coordinated by the solvent nitrile group in a calixarene adduct. According to

  18. Evolution of electrochemical performance in Li3V2(PO4)3/C composites caused by cation incorporation

    International Nuclear Information System (INIS)

    Zhang, Lu-Lu; Liang, Gan; Peng, Gang; Jiang, Yan; Fang, Hui; Huang, Yun-Hui; Croft, Mark C.; Ignatov, Alexander

    2013-01-01

    Graphical abstract: Four electrochemically active cations (M = Fe, Co, Ni, Mn) are doped into Li 3 V 2 (PO 4 ) 3 . M-incorporation does not change the monoclinic structure of Li 3 V 2 (PO 4 ) 3 , but forms some solid solutions. Minor LiMPO 4 impurity phases can be formed in the LVMP/C samples. Moreover, FePO 4 also exists as impurity in the LVFeP/C sample. Compared with pristine LVP/C, LVNiP/C electrode exhibits the lowest capacity, resulting from the decreased electronic conductivity and the lowest Li-ion diffusion coefficient, whereas LVFeP/C shows the best electrochemical performance. -- Highlights: • Cation-incorporated Li 3 V 2 (PO 4 ) 3 /C have been systematically investigated. • Cation incorporation in Li 3 V 2 (PO 4 ) 3 does not change the monoclinic structure but form solid solution. • Fe-incorporation shows the best electrochemical performance whereas Ni-incorporation shows the poorest performance. • A clear profile of cation incorporation with Fe, Co, Ni, Mn ions in Li 3 V 2 (PO 4 ) 3 /C is obtained. -- Abstract: Li 3 V 2 (PO 4 ) 3 /C (LVP/C) composites incorporated by a series of electrochemically active cations (Fe, Co, Ni, Mn) have been successfully prepared by a conventional solid-state reaction. M-incorporation (M = Fe, Co, Ni, Mn) in Li 3 V 2 (PO 4 ) 3 does not change the monoclinic structure. Analyzed with X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and high-resolution transmission electron microscopy, we find that the valence is between +2.67 and +3 for Fe, and is +2 for Co, Ni and Mn. M-doped LVP and LiMPO 4 phases coexist in the incorporated LVP/C composites. Compared with pristine LVP/C, Fe-incorporated LVP/C shows the best electrochemical performance with the highest initial discharge capacity of 131.4 mAh g −1 at 0.1 C between 2.5 and 4.3 V. The Fe-incorporated LVP/C sample also exhibits excellent rate capability with an average capacity of 122.4 mAh g −1 at 1 C and 93.5 mAh g −1 at 5 C, resulting from the

  19. The cation-π interaction.

    Science.gov (United States)

    Dougherty, Dennis A

    2013-04-16

    The chemistry community now recognizes the cation-π interaction as a major force for molecular recognition, joining the hydrophobic effect, the hydrogen bond, and the ion pair in determining macromolecular structure and drug-receptor interactions. This Account provides the author's perspective on the intellectual origins and fundamental nature of the cation-π interaction. Early studies on cyclophanes established that water-soluble, cationic molecules would forego aqueous solvation to enter a hydrophobic cavity if that cavity was lined with π systems. Important gas phase studies established the fundamental nature of the cation-π interaction. The strength of the cation-π interaction (Li(+) binds to benzene with 38 kcal/mol of binding energy; NH4(+) with 19 kcal/mol) distinguishes it from the weaker polar-π interactions observed in the benzene dimer or water-benzene complexes. In addition to the substantial intrinsic strength of the cation-π interaction in gas phase studies, the cation-π interaction remains energetically significant in aqueous media and under biological conditions. Many studies have shown that cation-π interactions can enhance binding energies by 2-5 kcal/mol, making them competitive with hydrogen bonds and ion pairs in drug-receptor and protein-protein interactions. As with other noncovalent interactions involving aromatic systems, the cation-π interaction includes a substantial electrostatic component. The six (four) C(δ-)-H(δ+) bond dipoles of a molecule like benzene (ethylene) combine to produce a region of negative electrostatic potential on the face of the π system. Simple electrostatics facilitate a natural attraction of cations to the surface. The trend for (gas phase) binding energies is Li(+) > Na(+) > K(+) > Rb(+): as the ion gets larger the charge is dispersed over a larger sphere and binding interactions weaken, a classical electrostatic effect. On other hand, polarizability does not define these interactions. Cyclohexane is

  20. Cation Effects on the Layer Structure of Biogenic Mn-Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, M.; Ginder-Vogel, M; Parikh, S; Feng, X; Sparks, D

    2010-01-01

    Biologically catalyzed Mn(II) oxidation produces biogenic Mn-oxides (BioMnO{sub x}) and may serve as one of the major formation pathways for layered Mn-oxides in soils and sediments. The structure of Mn octahedral layers in layered Mn-oxides controls its metal sequestration properties, photochemistry, oxidizing ability, and topotactic transformation to tunneled structures. This study investigates the impacts of cations (H{sup +}, Ni(II), Na{sup +}, and Ca{sup 2+}) during biotic Mn(II) oxidation on the structure of Mn octahedral layers of BioMnO{sub x} using solution chemistry and synchrotron X-ray techniques. Results demonstrate that Mn octahedral layer symmetry and composition are sensitive to previous cations during BioMnO{sub x} formation. Specifically, H{sup +} and Ni(II) enhance vacant site formation, whereas Na{sup +} and Ca{sup 2+} favor formation of Mn(III) and its ordered distribution in Mn octahedral layers. This study emphasizes the importance of the abiotic reaction between Mn(II) and BioMnO{sub x} and dependence of the crystal structure of BioMnO{sub x} on solution chemistry.

  1. A Study of Complexation-ability of Neutral Schiff Bases to Some Metal Cations

    Directory of Open Access Journals (Sweden)

    Umit Cakir

    2007-09-01

    Full Text Available The constants of the extraction equilibrium and the distribution fordichloromethane as an organic solvent having low dielectric constant of metal cations withchiral Schiff bases, benzaldehydene-(S-2-amino-3-phenylpropanol (I, o- benzaldehydene-(S-2-hydroxybenzaldehydene-(S-2-amino-3-phenyl-propanol (II,amino-3-methylbutanol (III with anionic dyes [4-(2-pyridylazo-resorcinol mono sodiummonohydrate (NaPar, sodium picrat (NaPic and potassium picrat (KPic] and some heavymetal chlorides were determined at 25 oC. All the ligands have given strongestcomplexation for NaPar. In contrast, similar behaviour for both alkali metal picrates is notapparent in the complexation of corresponding ligands.

  2. Virus-sized self-assembling lamellar complexes between plasmid DNA and cationic micelles promote gene transfer

    Science.gov (United States)

    Pitard, Bruno; Aguerre, Olivier; Airiau, Marc; Lachagès, Anne-Marie; Boukhnikachvili, Tsiala; Byk, Gérardo; Dubertret, Catherine; Herviou, Christian; Scherman, Daniel; Mayaux, Jean-François; Crouzet, Joël

    1997-01-01

    Gene therapy is based on the vectorization of genes to target cells and their subsequent expression. Cationic amphiphile-mediated delivery of plasmid DNA is the nonviral gene transfer method most often used. We examined the supramolecular structure of lipopolyamine/plasmid DNA complexes under various condensing conditions. Plasmid DNA complexation with lipopolyamine micelles whose mean diameter was 5 nm revealed three domains, depending on the lipopolyamine/plasmid DNA ratio. These domains respectively corresponded to negatively, neutrally, and positively charged complexes. Transmission electron microscopy and x-ray scattering experiments on complexes originating from these three domains showed that although their morphology depends on the lipopolyamine/plasmid DNA ratio, their particle structure consists of ordered domains characterized by even spacing of 80 Å, irrespective of the lipid/DNA ratio. The most active lipopolyamine/DNA complexes for gene transfer were positively charged. They were characterized by fully condensed DNA inside spherical particles (diameter: 50 nm) sandwiched between lipid bilayers. These results show that supercoiled plasmid DNA is able to transform lipopolyamine micelles into a supramolecular organization characterized by ordered lamellar domains. PMID:9405626

  3. The effect of pH on the complexation of Cd, Ni and Zn by dissolved organic carbon from leachate-polluted groundwater

    DEFF Research Database (Denmark)

    Christensen, J. B.; Christensen, Thomas Højlund

    2000-01-01

    model provided useful predictions of the complexation of Cd and Zn by DOC in the pH range 5±8, and of Ni in the pH range 5±7. At pH 8, however, the model overestimates the extent of Ni-DOC complexation to an unacceptable degree. The MINTEQA2 model predicts virtually no pH dependence for DOC complexation...

  4. Histidine, lysine, and arginine radical cations: isomer control via the choice of auxiliary ligand (L) in the dissociation of [CuII(L)amino acid]*2+ complexes.

    Science.gov (United States)

    Ke, Yuyong; Zhao, Junfang; Verkerk, Udo H; Hopkinson, Alan C; Siu, K W Michael

    2007-12-27

    Histidine, lysine, and arginine radical cations have been generated through collision-induced dissociation (CID) of complexes [CuII(auxiliary ligand)namino acid]*2+, using tri-, bi-, as well as monodentate auxiliary ligands. On the basis of the observed CID products, the existence of two isomeric amino-acid populations is postulated. The Type 1 radical cations of histidine and lysine, stable on the mass spectrometer time scale, were found to lose water, followed by the loss of carbon monoxide under more energetic CID conditions. The arginine Type 1 radical cation behaved differently, losing dehydroalanine. The Type 2 radical cations were metastable and easily fragmented by the loss of carbon dioxide, effectively preventing direct observation. Type 1 radical cations are proposed to result from neutral (canonical) amino-acid coordination, whereas Type 2 radical cations are from zwitterionic amino-acid coordination to copper in the complex. The ratio of Type 1/Type 2 ions was found to be dependent on the auxiliary ligand, providing a method of controlling which radical cation would be formed primarily. Density functional calculations at B3LYP/6-311++G(d,p) have been used to determine the relative energies of five His*+ isomers. Barriers against interconversion between the isomers and against fragmentation have been calculated, giving insight as to why the Type 1 ions are stable, while only fragmentation products of the Type 2 ions are observable under CID conditions.

  5. Study of electron transition energies between anions and cations in spinel ferrites using differential UV–vis absorption spectra

    International Nuclear Information System (INIS)

    Xue, L.C.; Wu, L.Q.; Li, S.Q.; Li, Z.Z.; Tang, G.D.; Qi, W.H.; Ge, X.S.; Ding, L.L.

    2016-01-01

    It is very important to determine electron transition energies (E_t_r) between anions and different cations in order to understand the electrical transport and magnetic properties of a material. Many authors have analyzed UV–vis absorption spectra using the curve (αhν)"2 vs E, where α is the absorption coefficient and E(=hν) is the photon energy. Such an approach can give only two band gap energies for spinel ferrites. In this paper, using differential UV–vis absorption spectra, dα/dE vs E, we have obtained electron transition energies (E_t_r) between the anions and cations, Fe"2"+ and Fe"3"+ at the (A) and [B] sites and Ni"2"+ at the [B] sites for the (A)[B]_2O_4 spinel ferrite samples Co_xNi_0_._7_−_xFe_2_._3O_4 (0.0≤x≤0.3), Cr_xNi_0_._7Fe_2_._3_−_xO_4 (0.0≤x≤0.3) and Fe_3O_4. We suggest that the differential UV–vis absorption spectra should be accepted as a general analysis method for determining electron transition energies between anions and cations.

  6. Thermodynamic model of Ni(II) solubility, hydrolysis and complex formation with ISA

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Siso, Maria Rosa; Duro, Lara; Bruno, Jordi [Amphos21, Barcelona (Spain); Gaona, Xavier; Altmaier, Marcus [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Nuclear Waste Disposal

    2018-04-01

    The solubility of β-Ni(OH){sub 2}(cr) was investigated at T=(22±2) C in the absence and presence of α-isosaccharinic acid (ISA), the main degradation product of cellulose under alkaline pH conditions. Batch solubility experiments were performed from undersaturation conditions under inert gas (Ar) atmosphere. Solubility experiments in the absence of ISA were conducted in 0.5 and 3.0 M NaCl-NaOH solutions at 7.5 ≤ pH{sub m} ≤ 13 (with pH{sub m} = -log{sub 10}[H{sup +}]). XRD analyses of selected solid phases collected after completing the solubility experiments (∼300 days) confirmed that β-Ni(OH){sub 2}(cr) remains as solid phase controlling the solubility of Ni(II) in all investigated conditions. Based on the slope analysis (log{sub 10}[Ni] vs. pH{sub m}) of the solubility data and solid phase characterization, the equilibrium reactions β-Ni(OH){sub 2}(cr)+2 H{sup +} <=> Ni{sup 2+}+2 H{sub 2}O(l) and β-Ni(OH){sub 2}(cr) <=> Ni(OH){sub 2}(aq) were identified as controlling the solubility of Ni(II) within the investigated pH{sub m} region. The conditional equilibrium constants determined from the solubility experiments at different ionic strengths were evaluated with the specific ion interaction theory (SIT). In contrast to the current thermodynamic selection in the NEA-TDB, solubility data collected in the present work does not support the formation of the anionic hydrolysis species Ni(OH){sub 3}{sup -} up to pH{sub m} ≤ 13.0. Solubility experiments in the presence of ISA were conducted in 0.5 M NaCl-NaOH-NaISA solutions with 0.01 M ≤ [NaISA] ≤ 0.2 M and 9 ≤ pH{sub m} ≤ 13. XRD analyses confirmed that β-Ni(OH){sub 2}(cr) is also the solid phase controlling the solubility of Ni(II) in the presence of ISA. Solubility data of all investigated systems can be properly explained with chemical and thermodynamic models including the formation of the complexes NiOHISA(aq), Ni(OH){sub 2}ISA{sup -} and Ni(OH){sub 3}ISA{sup 2-}. The reported data confirm

  7. Heterometallic Pd(II)-Ni(II) complexes with meso-substituted dibenzotetraaza[14]annulene: double C-H bond activation and formation of a rectangular tetradibenzotetraaza[14]annulene.

    Science.gov (United States)

    Khaledi, Hamid; Olmstead, Marilyn M; Fukuda, Takamitsu; Ali, Hapipah Mohd

    2014-11-03

    Three isomeric 2[Pd(II)-Ni(II)] metal complexes, derived from indoleninyl meso-substituted dibenzotetraaza[14]annulene, were synthesized. The resulting dimers feature Ni···Ni or, alternatively, Ni···π interactions in staggered or slipped cofacial structures. A remarkable insertion of palladium into two different C-H bonds yielded a 4[Pd(II)-Ni(II)] rectangular complex with dimensions of 8.73 × 10.38 Å.

  8. Interaction of cationic carbosilane dendrimers and their complexes with siRNA with erythrocytes and red blood cell ghosts.

    Science.gov (United States)

    Wrobel, Dominika; Kolanowska, Katarzyna; Gajek, Arkadiusz; Gomez-Ramirez, Rafael; de la Mata, Javier; Pedziwiatr-Werbicka, Elżbieta; Klajnert, Barbara; Waczulikova, Iveta; Bryszewska, Maria

    2014-03-01

    We have investigated the interactions between cationic NN16 and BDBR0011 carbosilane dendrimers with red blood cells or their cell membranes. The carbosilane dendrimers used possess 16 cationic functional groups. Both the dendrimers are made of water-stable carbon-silicon bonds, but NN16 possesses some oxygen-silicon bonds that are unstable in water. The nucleic acid used in the experiments was targeted against GAG-1 gene from the human immunodeficiency virus, HIV-1. By binding to the outer leaflet of the membrane, carbosilane dendrimers decreased the fluidity of the hydrophilic part of the membrane but increased the fluidity of the hydrophobic interior. They induced hemolysis, but did not change the morphology of the cells. Increasing concentrations of dendrimers induced erythrocyte aggregation. Binding of short interfering ribonucleic acid (siRNA) to a dendrimer molecule decreased the availability of cationic groups and diminished their cytotoxicity. siRNA-dendrimer complexes changed neither the fluidity of biological membranes nor caused cell hemolysis. Addition of dendriplexes to red blood cell suspension induced echinocyte formation. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Complexation of Cu2+, Ni2+ and UO22+ by radiolytic degradation products of bitumen

    International Nuclear Information System (INIS)

    Loon, L.R. Van; Kopajtic, Z.

    1990-05-01

    The radiolytic degradation of bitumen was studied under conditions which reflect those which will exist in the near field of a cementitious radioactive waste repository. The potential complexation capacity of the degradation products was studied and complexation experiments with Cu 2+ , Ni 2+ and UO 2 2+ were performed. In general 1:1 complexes with Cu 2+ , Ni 2+ and UO 2 2+ , with log K values of between 5.7 and 6.0 for Cu 2+ , 4.2 for Ni 2+ and 6.1 for UO 2 2+ , were produced at an ionic strength of 0.1 M. The composition of the bitumen water was analysed by GC-MS and IC. The major proportion of the bitumen degradation products in solution were monocarboxylic acids (acetic acid, formic acid, myric acid, stearic acid ...), dicarboxylic acids (oxalic acid, phthalic acid) and carbonates. The experimentally derived log K data are in good agreement with the literature and suggest that oxalate determines the speciation of Cu 2+ , Ni 2+ and UO 2 2+ in the bitumen water below pH=7. However, under the high pH conditions typical of the near field of a cementitious repository, competition with OH-ligands will be large and oxalate, therefore, will not play a significant role in the speciation of radionuclides. The main conclusion of the study is that the radiolytic degradation products of bitumen will have no influence on radionuclide speciation in a cementitious near field and, as such, need not to be considered in the appropriate safety assessment models. (author) 12 figs., 11 tabs., 31 refs

  10. Estudo da estabilidade do complexo ácido fítico e o íon Ni(II Study of stability of phytic acid with Ni(II complex

    Directory of Open Access Journals (Sweden)

    Ligia De Carli

    2006-03-01

    Full Text Available A técnica de titulação potenciométrica foi utilizada para verificar as propriedades ácida-base do ácido fítico [1,2,3,4,5,6-hexaquis(dihidrogenofosfato-mio-inositol] e do complexo ácido fítico e Ni(II, em solução aquosa, em temperatura e força iônica constantes. Para avaliar o comportamento térmico e a complexação do ácido fítico com o íon Ni(II foram realizadas análises de Termogravimetria (TG, Termogravimetria Derivada (DTG, Calorimetria Exploratória Diferencial (DSC e estudos de Espectrofotometria de Infravermelho. Foram obtidas oito constantes de protonação da amostra de ácido fítico na forma de sal de dipotássio e sete constantes de estabilidade do complexo ácido fítico e Ni(II. As reações de protonação e de formação ocorrem na faixa de pH de 2,0 a 11,0. Os dados obtidos mostram que o ácido fítico encontra-se totalmente deprotonado em pH 12,0 no qual a espécie ML (um ligante para um íon metálico encontra-se totalmente formada no mesmo valor de pH. Os resultados obtidos por TG e DSC revelaram tanto para o ácido fítico como para o complexo boa estabilidade até a temperatura próxima a 200ºC. Por TG, DTG e DSC conclui-se também que a estequiometria do complexo estudado foi de um mol de ligante para um mol de íon metálico. A Espectrofotometria de Infravermelho comprovou a estabilidade do ácido fítico e a sua interação com o íon Ni(II.The technique of potenciometric titration was used to verify the acid-basic properties of the phytic acid, [1,2,3,4,5,6-hexakis(dihydrogen phosphate-myo-inositol] and the Phytic Acid-Ni(II complex, in aqueous solution, in constant temperature and ionic strength. To evaluate the thermal behavior end complexation of the isolated phytic acid with the Ni(II were performed analyses of thermogravimetry (TG, calorimetric scanning differential (DSC and studies Spectroscopy Infrared (IR. Eight protonation constants of the phytic acid sample as dipotassium salt were

  11. Synthesis, crystal structure and photoluminescence study of green light emitting bis(1[(4-butylphenylimino]methyl naphthalen-2-ol Ni(II complex

    Directory of Open Access Journals (Sweden)

    M. Srinivas

    2016-09-01

    Full Text Available Synthetically feasible and cost effective Ni(II complex phosphor (4 as green organic light emitting diode (OLED was prepared by using Schiff base 1-[(4-butylphenylimino]methyl naphthalen-2-ol (3. The single crystals of Ni(II complex were grown from chloroform and hexane (1:1 v/v solution. The green crystals of the complex were characterized by using single crystal XRD studies and were evaluated for their photophysical properties. From the Diffused Reflectance Spectrum of the complex, the measured band gap energy was found to be 1.83 eV and the PL spectrum of the complex showed emission peak at 519 nm. The excitation peaks at 519 nm were appeared at 394 nm and 465 nm. The Commission Internationale De L'Eclairage (CIE chromaticity diagram indicated that, the complex exhibit green color. Hence, Ni(II complex (4 could be a promising green OLED for developing strong electroluminescent materials for flat panel display applications.

  12. Tris(propane-1,2-diamine-κ2N,N′nickel(II tetracyanidonickelate(II

    Directory of Open Access Journals (Sweden)

    Juraj Černák

    2008-02-01

    Full Text Available The title compound, [Ni(C3H10N23][Ni(CN4], is built up of [Ni(pn3]2+ cations (pn is 1,2-diaminopropane and [Ni(CN4]2− anions. Both NiII atoms in the cation and the anion lie on a mirror plane. The respective ions interact through Coulombic forces and through a complex network of hydrogen bonds. Extended disorder associated with the cation has been resolved. The occupancies of the respective disordered positions are 0.4:0.4:0.2.

  13. Effect of synthesis methods with different annealing temperatures on micro structure, cations distribution and magnetic properties of nano-nickel ferrite

    Energy Technology Data Exchange (ETDEWEB)

    El-Sayed, Karimat [XRD Lab, Physics Department, Faculty of Science, Ain-Shams University, Cairo (Egypt); Mohamed, Mohamed Bakr, E-mail: mbm1977@yahoo.com [XRD Lab, Physics Department, Faculty of Science, Ain-Shams University, Cairo (Egypt); Hamdy, Sh.; Ata-Allah, S.S. [Reactor Physics Department, NRC, Atomic Energy Authority, P.O. Box 13759, Cairo (Egypt)

    2017-02-01

    Nano-crystalline NiFe{sub 2}O{sub 4} was synthesized by citrate and sol–gel methods at different annealing temperatures and the results were compared with a bulk sample prepared by ceramic method. The effect of methods of preparation and different annealing temperatures on the crystallize size, strain, bond lengths, bond angles, cations distribution and degree of inversions were investigated by X-ray powder diffraction, high resolution transmission electron microscope, Mössbauer effect spectrometer and vibrating sample magnetometer. The cations distributions were determined at both octahedral and tetrahedral sites using both Mössbauer effect spectroscopy and a modified Bertaut method using Rietveld method. The Mössbauer effect spectra showed a regular decrease in the hyperfine field with decreasing particle size. Saturation magnetization and coercivity are found to be affected by the particle size and the cations distribution. - Highlights: • Annealed nano NiFe{sub 2}O{sub 4} was prepared by different methods. • The crystallite sizes are critical. • Mössbauer spectra show superparamagnetic doublet. • Cations distributions by MÓ§ssbauer and Bertaut method are constituents. • Cations distribution are significantly affects the magnetic properties.

  14. Hydrocolloid liquid-core capsules for the removal of heavy-metal cations from water

    Energy Technology Data Exchange (ETDEWEB)

    Nussinovitch, A., E-mail: amos.nussi@mail.huji.ac.il; Dagan, O.

    2015-12-15

    Highlights: • Novel liquid-core capsules with a non-crosslinked alginate core were produced. • Capsules demonstrated highest efficiency adsorption of ∼300 mg Pb{sup 2+}/g alginate. • Regeneration was carried out by suspending capsules in 1 M HNO{sub 3} for 24 h. • Adsorption capacities of the capsules followed the order: Pb{sup 2+} > Cu{sup 2+} > Cd{sup 2+} > Ni{sup 2+}. - Abstract: Liquid-core capsules with a non-crosslinked alginate fluidic core surrounded by a gellan membrane were produced in a single step to investigate their ability to adsorb heavy metal cations. The liquid-core gellan–alginate capsules, produced by dropping alginate solution with magnesium cations into gellan solution, were extremely efficient at adsorbing lead cations (267 mg Pb{sup 2+}/g dry alginate) at 25 °C and pH 5.5. However, these capsules were very weak and brittle, and an external strengthening capsule was added by using magnesium cations. The membrane was then thinned with the surfactant lecithin, producing capsules with better adsorption attributes (316 mg Pb{sup +2}/g dry alginate vs. 267 mg Pb{sup +2}/g dry alginate without lecithin), most likely due to the thinner membrane and enhanced mass transfer. The capsules’ ability to adsorb other heavy-metal cations – copper (Cu{sup 2+}), cadmium (Cd{sup 2+}) and nickel (Ni{sup 2+}) – was tested. Adsorption efficiencies were 219, 197 and 65 mg/g, respectively, and were correlated with the cation’s affinity to alginate. Capsules with the sorbed heavy metals were regenerated by placing in a 1 M nitric acid suspension for 24 h. Capsules could undergo three regeneration cycles before becoming damaged.

  15. Bisamidate and Mixed Amine/Amidate NiN2S2 Complexes as Models for Nickel-Containing Acetyl Coenzyme A Synthase and Superoxide Dismutase: An Experimental and Computational Study

    International Nuclear Information System (INIS)

    Mathrubootham, V.; Thomas, J.; Staples, R.; McCraken, J.; Shearer, J.; Hegg, E.

    2010-01-01

    The distal nickel site of acetyl-CoA synthase (Ni d -ACS) and reduced nickel superoxide dismutase (Ni-SOD) display similar square-planar Ni II N 2 S 2 coordination environments. One difference between these two sites, however, is that the nickel ion in Ni-SOD contains a mixed amine/amidate coordination motif while the Ni d site in Ni-ACS contains a bisamidate coordination motif. To provide insight into the consequences of the different coordination environments on the properties of the Ni ions, we systematically examined two square-planar Ni II N 2 S 2 complexes, one with bisthiolate-bisamidate ligation (Et 4 N) 2 (Ni(L1))·2H 2 O (2) (H 4 L1 = N-(2-mercaptoacetyl)-N(prime)-(2-mercaptoethyl)glycinamide) and another with bisthiolate-amine/amidate ligation K(Ni(HL2)) (3) (H 4 L2 = N-(2(double p rime)-mercaptoethyl)-2- ((2(prime)-mercaptoethyl)amino)acetamide). Although these two complexes differ only by a single amine versus amidate ligand, their chemical properties are quite different. The stronger in-plane ligand field in the bisamidate complex (Ni II (L1)) 2- (2) results in an increase in the energies of the d → d transitions and a considerably more negative oxidation potential. Furthermore, while the bisamidate complex (Ni II (L1)) 2- (2) readily forms a trinuclear species (Et 4 N) 2 ({Ni(L1)} 2 Ni)·H 2 O (1) and reacts rapidly with O 2 , presumably via sulfoxidation, the mixed amine/amidate complex (Ni II (HL2)) - (3) remains monomeric and is stable for days in air. Interestingly, the Ni III species of the bisamidate complex formed by chemical oxidation with I 2 can be detected by electron paramagnetic resonance (EPR) spectroscopy while the mixed amine/amidate complex immediately decomposes upon oxidation. To explain these experimentally observed properties, we performed S K-edge X-ray absorption spectroscopy and low-temperature (77 K) electronic absorption measurements as well as both hybrid density functional theory (hybrid-DFT) and spectroscopy oriented

  16. Synthesis and characterization of Ni(II, Cu(II and Co(III complexes with polyamine-containing macrocycles bearing an aminoethyl pendant arm

    Directory of Open Access Journals (Sweden)

    K. S. SIDDIQI

    2004-09-01

    Full Text Available Reaction of [M(ppn2]X2 (where M = Cu(II, Ni(II, Co(II and ppn = 1,3-diaminopropane with formaldehyde and ethylenediamine in methanol results in the ready formation of a 16-membered macrocyclic complex. The complexes were characterized by elemental anlysis, IR, EPR, electronic spectral data, magnetic moments and conductance measurements. The Cu(II, Ni(II and Co(III complexes are coordinated axially with both pendant groups of the hexadentate macrocycle. These pendant donors are attached to the macrocycle by a carbon chain. The electrical conductivities of the Cu(II and Ni(II chelates indicated them to be 1:2 electrolytes whilst those of Co(III is a 1:3 electrolyte in DMSO. The EPR spectrum of the copper complex exhibited G at 3.66, which indicates a considerable exchange interaction in the complex. Spectroscopic evidence suggests that in all of the complexes the metal ion is in an octahedral environment.

  17. Complexes of Cu(II), Ni(II), Co(II), oxovanadium(IV) and dioxouranium(VI) with N,N'-ethylenebis (2-hydroxy-4-methylpropiophenoneimine)

    International Nuclear Information System (INIS)

    Patel, M.M.; Patel, M.R.; Patel, M.N.; Patel, R.P.

    1982-01-01

    Complexes of Cu(II), Ni(II), Co(II), oxovanadium(IV) and dioxouranium(VI) with the schiff base, N,N'-ethylenebis(2-hydroxy-4-methylpropiophenoneimine)(4-MeOHPEN), have been synthesised and characterised on the basis of elemental analyses, conductivity, magnetic moment, electronic and infrared spectral data. Square-planar structures are suggested for Cu(II), Ni(II) and Co(II) complexes while a distorted square-pyramidal structure is suggested for the oxovanadium(IV) complex. (author)

  18. M(Al,Ni)-TiO2-Based Photoanode for Photoelectrochemical Solar Cells

    Science.gov (United States)

    Navas, Javier; Reyes-Pérez, Fran; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Bernal, Juan Jesús Gallardo; Martín-Calleja, Joaquín

    2018-05-01

    This study presents the incorporation of Al and Ni cations onto the surface of TiO2 nanoparticles used as photoelectrode in dye sensitized solar cells (DSSCs). The incorporation of these cations was performed using the chemical bath deposition (CBD) technique. This process was applied up to three times to evaluate the semiconductors' properties with respect to the amount of Al and Ni. The M(Al,Ni)-TiO2-based semiconductors were widely characterized using techniques such as X-ray fluorescence, X-ray diffraction, Raman spectroscopy, UV-Vis spectroscopy and X-ray photoelectron spectroscopy. The presence of (hydr)oxide species of Al(III) and Ni(II) was confirmed and anatase was the predominant crystalline phase obtained. Moreover, for both elements, a decrease in the band gap energy was observed, this being more pronounced after the incorporation of Ni. Furthermore, the use of the M(Al,Ni)-TiO2-based semiconductors as photoelectrodes in DSSCs led to an increase in the open-circuit voltage of up to 22% and 10% for the incorporation of Al and Ni, respectively. This increase can be reasonably explained by the negative shift of the flat band potential of the photoelectrodes. EIS measurements were performed to study the electron transport kinetics in the photoelectrode and the internal resistance in the DSSCs to understand the photocurrent density values obtained.

  19. Complexation of the cesium cation with 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6

    Czech Academy of Sciences Publication Activity Database

    Makrlík, E.; Dybal, Jiří; Vaňura, P.

    2013-01-01

    Roč. 295, č. 2 (2013), s. 1299-1303 ISSN 0236-5731 R&D Projects: GA ČR GA203/09/1478 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : cesium cation * substituted calix[4]arene-crown-6 * complexation Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.415, year: 2013

  20. Ni(II) complexes of arginine Schiff-bases and its interaction with DNA

    Energy Technology Data Exchange (ETDEWEB)

    Sallam, S.A., E-mail: shehabsallam@yahoo.com [Chemistry Department, Faculty of Science, Suez Canal University, Isamilia (Egypt); Abbas, A.M. [Chemistry Department, Faculty of Science, Suez Canal University, Isamilia (Egypt)

    2013-04-15

    Ni(II) complexes with Schiff-bases obtained by condensation of arginine with salicylaldehyde; 2,3-; 2,4-; 2,5-dihydroxybenzaldehyde and o-hydroxynaphthaldehyde have been synthesized using the template method in ethanol or ammonia media. They were characterized by elemental analyses, conductivity measurements, magnetic moment, UV, IR and {sup 1}H NMR spectra as well as thermal analysis (TG, DTG and DTA). The Schiff-bases are dibasic tridentate donors and the complexes have diamagnetic square planar and octahedral structures. The complexes decompose in three steps where kinetic and thermodynamic parameters of the decomposition steps were computed. The interactions of the formed complexes with FM-DNA were monitored by UV and fluorescence spectroscopy. -- Highlights: ► Arginine Schiff-bases and their nickel(II) complexes have been synthesized. ► Magnetic and spectral data show diamagnetic square planar and octahedral complexes. ► The complexes thermally decompose in three stages. Interaction with FM-DNA shows hyperchromism with blue shift.

  1. Ni(II) complexes of arginine Schiff-bases and its interaction with DNA

    International Nuclear Information System (INIS)

    Sallam, S.A.; Abbas, A.M.

    2013-01-01

    Ni(II) complexes with Schiff-bases obtained by condensation of arginine with salicylaldehyde; 2,3-; 2,4-; 2,5-dihydroxybenzaldehyde and o-hydroxynaphthaldehyde have been synthesized using the template method in ethanol or ammonia media. They were characterized by elemental analyses, conductivity measurements, magnetic moment, UV, IR and 1 H NMR spectra as well as thermal analysis (TG, DTG and DTA). The Schiff-bases are dibasic tridentate donors and the complexes have diamagnetic square planar and octahedral structures. The complexes decompose in three steps where kinetic and thermodynamic parameters of the decomposition steps were computed. The interactions of the formed complexes with FM-DNA were monitored by UV and fluorescence spectroscopy. -- Highlights: ► Arginine Schiff-bases and their nickel(II) complexes have been synthesized. ► Magnetic and spectral data show diamagnetic square planar and octahedral complexes. ► The complexes thermally decompose in three stages. Interaction with FM-DNA shows hyperchromism with blue shift

  2. Adsorption and co-adsorption of graphene oxide and Ni(II) on iron oxides: A spectroscopic and microscopic investigation.

    Science.gov (United States)

    Sheng, Guodong; Huang, Chengcai; Chen, Guohe; Sheng, Jiang; Ren, Xuemei; Hu, Baowei; Ma, Jingyuan; Wang, Xiangke; Huang, Yuying; Alsaedi, Ahmed; Hayat, Tasawar

    2018-02-01

    Graphene oxide (GO) may strongly interact with toxic metal ions and mineral particles upon release into the soil environment. We evaluated the mutual effects between GO and Ni (Ni(II)) with regard to their adsorption and co-adsorption on two minerals (goethite and hematite) in aqueous phase. Results indicated that GO and Ni could mutually facilitate the adsorption of each other on both goethite and hematite over a wide pH range. Addition of Ni promoted GO co-adsorption mainly due to the increased positive charge of minerals and cation-π interactions, while the presence of GO enhanced Ni co-adsorption predominantly due to neutralization of positive charge and strong interaction with oxygen-containing functional groups on adsorbed GO. Increasing adsorption of GO and Ni on minerals as they coexist may thus reduce their mobility in soil. Extended X-ray absorption fine structure (EXAFS) spectroscopy data revealed that GO altered the microstructure of Ni on minerals, i.e., Ni formed edge-sharing surface species (at R Ni-Fe ∼3.2 Å) without GO, while a GO-bridging ternary surface complexes (at R Ni-C ∼2.49 Å and R Ni-Fe ∼4.23 Å) was formed with GO. These findings improved the understanding of potential fate and toxicity of GO as well as the partitioning processes of Ni ions in aquatic and soil environments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Asymmetric synthesis of α-amino acids via homologation of Ni(II) complexes of glycine Schiff bases. Part 3: Michael addition reactions and miscellaneous transformations.

    Science.gov (United States)

    Aceña, José Luis; Sorochinsky, Alexander E; Soloshonok, Vadim

    2014-09-01

    The major goal of this review is a critical discussion of the literature data on asymmetric synthesis of α-amino acids via Michael addition reactions involving Ni(II)-complexes of amino acids. The material covered is divided into two conceptually different groups dealing with applications of: (a) Ni(II)-complexes of glycine as C-nucleophiles and (b) Ni(II)-complexes of dehydroalanine as Michael acceptors. The first group is significantly larger and consequently subdivided into four chapters based on the source of stereocontrolling element. Thus, a chiral auxiliary can be used as a part of nucleophilic glycine Ni(II) complex, Michael acceptor or both, leading to the conditions of matching vs. mismatching stereochemical preferences. The particular focus of the review is made on the practical aspects of the methodology under discussion and mechanistic considerations.

  4. Synthesis and characterization of n-type NiO:Al thin films for fabrication of p-n NiO homojunctions

    Science.gov (United States)

    Sun, Hui; Liao, Ming-Han; Chen, Sheng-Chi; Li, Zhi-Yue; Lin, Po-Chun; Song, Shu-Mei

    2018-03-01

    n-type NiO:Al thin films were deposited by RF magnetron sputtering. Their optoelectronic properties versus Al target power was investigated. The results show that with increasing Al target power, the conduction type of NiO films changes from p-type to n-type. The variation of the film’s electrical and optical properties depends on Al amount in the film. When Al target power is relatively low, Al3+ cations tend to enter nickel vacancy sites, which makes the lattice structure of NiO more complete. This improves the carrier mobility and film’s transmittance. However, when Al target power exceeds 40 W, Al atoms begin to enter into interstitial sites and form an Al cluster in the NiO film. This behavior is beneficial for improving the film’s n-type conductivity but degrades the film’s transmittance. Finally, Al/(p-type NiO)/(n-type NiO:Al)/ITO homojunctions were fabricated. Their performance was compared with Al/(p-type NiO)/ITO heterojunctions without an n-type NiO layer. Thanks to the better interface quality between the two NiO layers, the homojunctions present better performance.

  5. Decreasing Ni, Cu, Cd, and Zn heavy metal magnetite-bentonite nanocomposites and adsorption isotherm study

    Science.gov (United States)

    Eskandari, M.; Zakeri Khatir, M.; Khodadadi Darban, A.; Meshkini, M.

    2018-04-01

    This present study was conducted to investigate the effect of magnetite-bentonite nanocomposite on heavy metal removal from an effluent. For this purpose, magnetite-bentonite nanocomposite was prepared through the chemical method and characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, followed by studying the effect of produced nanocomposite on the removal of Ni2+, Cu2+, Cd2+, and Zn2+ heavy metal ions. The results showed that adsorption capacity of magnetite-bentonite nanocomposites for the studied ions is in the order of Zn2+ > Cd2+ > Cu2+ > Ni2+. Adsorption isotherms were drawn for Ni2+, Cu2+, Cd2+, and Zn2+ cations and found that cations adsorption on nanocomposite fit into Langmuir model.

  6. Effective removal of Ni(II) from aqueous solutions by modification of nano particles of clinoptilolite with dimethylglyoxime.

    Science.gov (United States)

    Nezamzadeh-Ejhieh, Alireza; Kabiri-Samani, Mehdi

    2013-09-15

    In this work an Iranian natural clinoptilolite tuff was pre-treated and changed to the micro (MCP) and nano (NCP) particles by mechanical method. Modification of micro and nano particles and also their Ni-exchanged forms were done by dimethylglyoxime (DMG). The raw and modified samples were characterized by XRD, FT-IR, SEM, BET, TG-DTG and energy dispersive analysis X-ray spectroscopy (EDAX). Removal of Ni(II) by modified and unmodified samples was investigated in batch procedure. It was found that NCP-DMG has higher capacity for removal of Ni(II). The effects of analytical parameters such as pH, dose of DMG, concentration of nickel solution, contact time and selectivity were studied and the optimal operation parameters were found as follows: pHPZC: 7.6, CNi(II): 0.01 M, contact time: 360 min and DMG dosage: 5mM. The results of selectivity experiments showed that the modified zeolite has a good selectivity for nickel in the presence of different multivalent cations. Langmuir and Freundlich isotherm models were adopted to describe the adsorption isotherms. Adsorption isotherms of Ni(II) ions could be best modelled by Langmuir equation, that indicate the monolayer sorption of Ni(II). Comparison of two kinetic models indicates that the adsorption kinetic can be well described by the pseudo-second-order rate equation that indicates that the rate limiting step for the process involves chemical reaction. The negative ΔH and ΔG indicate an exothermic and spontaneously process. The negative ΔS indicates that the adsorption of nickel cations from solution occurs with lower amount ion replacement, thus chemisorptions due to complex formation are dominant process in nickel removal. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Al cation induces aggregation of serum proteins.

    Science.gov (United States)

    Chanphai, P; Kreplak, L; Tajmir-Riahi, H A

    2017-07-15

    Al cation is known to induce protein fibrillation and causes several neurodegenerative disorders. We report the spectroscopic, thermodynamic analysis and AFM imaging for the Al cation binding process with human serum albumin (HSA), bovine serum albumin (BSA) and milk beta-lactoglobulin (b-LG) in aqueous solution at physiological pH. Hydrophobicity played a major role in Al-protein interactions with more hydrophobic b-LG forming stronger Al-protein complexes. Thermodynamic parameters ΔS, ΔH and ΔG showed Al-protein bindings occur via hydrophobic and H-bonding contacts for b-LG, while van der Waals and H-bonding interactions prevail in HSA and BSA adducts. AFM clearly indicated that aluminum cations are able to force BSA and b-LG into larger or more robust aggregates than HSA, with HSA 4±0.2 (SE, n=801) proteins per aggregate, for BSA 17±2 (SE, n=148), and for b-LG 12±3 (SE, n=151). Thioflavin T test showed no major protein fibrillation in the presence of Al cation. Al complexation induced major alterations of protein conformations with the order of perturbations b-LG>BSA>HSA. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Mutual influence between triel bond and cation-π interactions: an ab initio study

    Science.gov (United States)

    Esrafili, Mehdi D.; Mousavian, Parisasadat

    2017-12-01

    Using ab initio calculations, the cooperative and solvent effects on cation-π and B...N interactions are studied in some model ternary complexes, where these interactions coexist. The nature of the interactions and the mechanism of cooperativity are investigated by means of quantum theory of atoms in molecules (QTAIM), noncovalent interaction (NCI) index and natural bond orbital analysis. The results indicate that all cation-π and B...N binding distances in the ternary complexes are shorter than those of corresponding binary systems. The QTAIM analysis reveals that ternary complexes have higher electron density at their bond critical points relative to the corresponding binary complexes. In addition, according to the QTAIM analysis, the formation of cation-π interaction increases covalency of B...N bonds. The NCI analysis indicates that the cooperative effects in the ternary complexes make a shift in the location of the spike associated with each interaction, which can be regarded as an evidence for the reinforcement of both cation-π and B...N interactions in these systems. Solvent effects on the cooperativity of cation-π and B...N interactions are also investigated.

  9. The Formation of Metal (M=Co(II), Ni(II), and Cu(II)) Complexes by Aminosilanes Immobilized within Mesoporous Molecular Sieves

    International Nuclear Information System (INIS)

    Park, Dong Ho; Park, Sung Soo; Choe, Sang Joon

    1999-01-01

    The immobilization of APTMS(3-(2-aminoethylamino)propyltrimethoxysilane) and AAPTMS(3-(2-(2-aminoethyl) aminoethylamino)propyltrimethoxysilane) on the surface of high quality mesoporous molecular sieves MCM-41 and MCM-48 have been confirmed by F.T.-IR spectroscopy, Raman spectroscopy, 29 Si solid state NMR, and a surface polarity measurement using Reichardt's dye. The formation of metal (Co(II), Ni(II), and Cu(II)) complexes by immobilized aminosilanes have been investigated by photoacoustic spectroscopy(PAS). The assignment of UV-Vis. PAS bands makes it possible to identify the structure of metal complexes within mesoporous molecular sieves. Co(II) ion may be coordinated mainly in a tetrahedral symmetry by two APTMS onto MCM-41, and in an octahedral one by two AAPTMS. Both Ni(II) and Cu(II) coordinated by aminosilanes within MCM-41 form possibly the octahedral complexes such as [Ni(APTMS) 2 (H 2 O) 2 ] 2+ , [Ni(AAPTMS) 2 ] 2+ , [Cu(APTMS) 2 (H 2 O) 2 ] 2+ , and [Cu(AAPTMS)(H 2 O) 3 ] 2+ , respectively. The PAS band shapes of complexes onto MCM-48 are similar to those of corresponding MCM-41 with the variation of PAS intensity. Most of metal ion(II) within MCM-41 and MCM-48 are coordinated by aminosilanes without the impregnation on the surface

  10. Synthesis and spectroscopic studies of biologically active tetraazamacrocyclic complexes of Mn(II, Co(II, Ni(II, Pd(II and Pt(II

    Directory of Open Access Journals (Sweden)

    Monika Tyagi

    2014-01-01

    Full Text Available Complexes of Mn(II, Co(II, Ni(II, Pd(II and Pt(II were synthesized with the macrocyclic ligand, i.e., 2,3,9,10-tetraketo-1,4,8,11-tetraazacycoletradecane. The ligand was prepared by the [2 + 2] condensation of diethyloxalate and 1,3-diamino propane and characterized by elemental analysis, mass, IR and 1H NMR spectral studies. All the complexes were characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, IR, electronic and electron paramagnetic resonance spectral studies. The molar conductance measurements of Mn(II, Co(II and Ni(II complexes in DMF correspond to non electrolyte nature, whereas Pd(II and Pt(II complexes are 1:2 electrolyte. On the basis of spectral studies an octahedral geometry has been assigned for Mn(II, Co(II and Ni(II complexes, whereas square planar geometry assigned for Pd(II and Pt(II. In vitro the ligand and its metal complexes were evaluated against plant pathogenic fungi (Fusarium odum, Aspergillus niger and Rhizoctonia bataticola and some compounds found to be more active as commercially available fungicide like Chlorothalonil.

  11. Stability constants for some divalent metal ion/crown ether complexes in methanol determined by polarography and conductometry

    NARCIS (Netherlands)

    Chen, L.; Bos, M.; Grootenhuis, P.D.J.; Christenhusz, A.; Hoogendam, E.; Reinhoudt, David; van der Linden, W.E.

    1987-01-01

    Stability constants in methanol at 25.0°C were evaluated for the complexes of the divalent cations Ca2+, Ni2+, Zn2+, Pb2+, Mg2+, Co2+ and Cu2+ with the macrocyclic polyethers 15-crown-5 (15C5), 18-crown-6 (18C6), dicyclohexyl-18-crown-6 (DC18C6) and dibenzo-24-crown-8 (DB24C8). The log K values of

  12. Cation Exchange Efficiency Of Modified Bentonite Using In-Situ GAMMA Radiation Polymerization Of Acrylic Acid Or Acrylamide

    International Nuclear Information System (INIS)

    ISMAIL, S.A.; FALAZI, B.

    2009-01-01

    Modified bentonites as cation exchangers were prepared by treating raw bentonite with 3N NaOH at 95 0 C followed by in-situ polymerization using gamma irradiation as well as hydrogen peroxide initiation of acrylic acid or acrylamide in the matrix.Water swelling and acid capacity were determined and cation exchange capacity for Cu 2+ , Ni 2+ and Co 2+ was evaluated. It has been found that catiexchange capacity of treated bentonite was increased as result of formed polyacrylic acid and polyacrylamide in the matrix. In case of acrylic acid, the maximum cation exchange capacities of 3.5, 3.1 and 2.5 mg equivalent/g were determined for Cu 2+ , Ni 2+ and Co 2+ , respectively, and for acrylamide, the corresponding capacities were 2.9, 2.8 and 2.6 mg equivalent/g, respectively. Water swelling was found to be associated with holding large amounts of water, for instance, 49 g of water was sorbed per one gram of the sodium salt form of polyacrylic acid in bentonite matrix, in other words the degree of swelling in water achieved 4500%.

  13. Predicting Organic Cation Sorption Coefficients: Accounting for Competition from Sorbed Inorganic Cations Using a Simple Probe Molecule.

    Science.gov (United States)

    Jolin, William C; Goyetche, Reaha; Carter, Katherine; Medina, John; Vasudevan, Dharni; MacKay, Allison A

    2017-06-06

    estimation of K d values for more structurally complex organic cations to homoionic montmorillonites and to heteroionic soils (mean absolute error of 0.27 log unit). Accordingly, we concluded that the use of phenyltrimethylammonium as a probe compound was a promising means to account for the identity, affinity, and abundance of natural exchange ions in the prediction of organic cation sorption coefficients for environmental solids.

  14. A density functional theory and quantum theory of atoms-in-molecules analysis of the stability of Ni(II) complexes of some amino alcohol ligands.

    Science.gov (United States)

    Varadwaj, Pradeep R; Cukrowski, Ignacy; Perry, Christopher B; Marques, Helder M

    2011-06-23

    The structure of the complexes of the type [Ni(L)(H(2)O)(2)](2+), where L is an amino alcohol ligand, L = N,N'-bis(2-hydroxyethyl)-ethane-1,2-diamine (BHEEN), N,N'-bis(2-hydroxycyclohexyl)-ethane-1,2-diamine (Cy(2)EN), and N,N'-bis(2-hydroxycyclopentyl)-ethane-1,2-diamine, (Cyp(2)EN) were investigated at the X3LYP/6-31+G(d,p) level of theory both in the gas phase and in solvent (CPCM model) to gain insight into factors that control the experimental log K(1) values. We find that (i) analyses based on Bader's quantum theory of atoms in molecules (QTAIM) are useful in providing significant insight into the nature of metal-ligand bonding and in clarifying the nature of weak "nonbonded" interactions in these complexes and (ii) the conventional explanation of complex stability in these sorts of complexes (based on considerations of bond lengths, bite angles and H-clashes) could be inadequate and indeed might be misleading. The strength of metal-ligand bonds follows the order Ni-N > Ni-OH ≥ Ni-OH(2); the bonds are predominantly ionic with some covalent character decreasing in the order Ni-N > Ni-OH > Ni-OH(2), with Ni-OH(2) being close to purely ionic. We predict that the cis complexes are preferred over the trans complexes because of (i) stronger bonding to the alcoholic O-donor atoms and (ii) more favorable intramolecular interactions, which appear to be important in determining the conformation of a metal-ligand complex. We show that (i) the flexibility of the ligand, which controls the Ni-OH bond length, and (ii) the ability of the ligand to donate electron density to the metal are likely to be important factors in determining values of log K(1). We find that the electron density at the ring critical point of the cyclopentyl moieties in Cyp(2)EN is much higher than that in the cyclohexyl moieties of Cy(2)EN and interpret this to mean that Cyp(2)EN is a poorer donor of electron density to a Lewis acid than Cy(2)EN.

  15. Complexation of biological ligands with lanthanides(III) for MRI: Structure, thermodynamic and methods; Complexation des cations lanthanides trivalents par des ligands d'origine biologique pour l'IRM: Structure, thermodynamique et methodes

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet, C

    2006-07-15

    New cyclic ligands derived from sugars and amino-acids form a scaffold carrying a coordination sphere of oxygen atoms suitable to complex Ln(III) ions. In spite of their rather low molecular weights, the complexes display surprisingly high relaxivity values, especially at high field. The ACX and BCX ligands, which are acidic derivatives of modified and cyclo-dextrins, form mono and bimetallic complexes with Ln(III). The LnACX and LnBCX complexes show affinities towards Ln(III) similar to those of tri-acidic ligands. In the bimetallic Lu2ACX complex, the cations are deeply embedded in the cavity of the ligand, as shown by the X-ray structure. In aqueous solution, the number of water molecules coordinated to the cation in the LnACX complex depends on the nature and concentration of the alkali ions of the supporting electrolyte, as shown by luminescence and relaxometric measurements. There is only one water molecule coordinated in the LnBCX complex, which enables us to highlight an important second sphere contribution to relaxivity. The NMR study of the RAFT peptidic ligand shows the complexation of Ln(III), with an affinity similar to those of natural ligands derived from calmodulin. The relaxometric study also shows an important second sphere contribution to relaxivity. To better understand the intricate molecular factors affecting relaxivity, we developed new relaxometric methods based on probe solutes. These methods allow us to determine the charge of the complex, weak affinity constants, trans-metallation constants, and the electronic relaxation rate. (author)

  16. Effects of metallic cations in the beryl flotation

    International Nuclear Information System (INIS)

    Lima Leonel, C.M. de; Peres, A.E.C.

    1984-01-01

    The beryl zeta potential in microelectrophoretic cell is studied in the presence of neutral electrolyte, cations of calcium, magnesium and iron. The petroleum sulfonate is used how collector in Hallimond tube. Hydroxy complex of metallic cations seems activate the ore and precipitates of colloidal metallic hidroxies seems lower him when added to the mixture. (M.A.C.) [pt

  17. Hydrogen Activation by Biomimetic [NiFe]-Hydrogenase Model Containing Protected Cyanide Cofactors

    Science.gov (United States)

    Manor, Brian C.; Rauchfuss, Thomas B.

    2013-01-01

    Described are experiments that allow incorporation of cyanide cofactors and hydride substrate into active site models [NiFe]-hydrogenases (H2ases). Complexes of the type (CO)2(CN)2Fe(pdt)Ni(dxpe), (dxpe = dppe, 1; dxpe = dcpe, 2) bind the Lewis acid B(C6F5)3 (BArF3) to give the adducts (CO)2(CNBArF3)2Fe(pdt)Ni(dxpe), (1(BArF3)2, 2(BArF3)2). Upon decarbonylation using amine oxides, these adducts react with H2 to give hydrido derivatives Et4N[(CO)(CNBArF3)2Fe(H)(pdt)Ni(dxpe)], (dxpe = dppe, Et4N[H3(BArF3)2]; dxpe = dcpe, Et4N[H4(BArF3)2]). Crystallographic analysis shows that Et4N[H3(BArF3)2] generally resembles the active site of the enzyme in the reduced, hydride-containing states (Ni-C/R). The Fe-H…Ni center is unsymmetrical with rFe-H = 1.51(3) and rNi-H = 1.71(3) Å. Both crystallographic and 19F NMR analysis show that the CNBArF3− ligands occupy basal and apical sites. Unlike cationic Ni-Fe hydrides, [H3(BArF3)2]− and [H4(BArF3)2]− oxidize at mild potentials, near the Fc+/0 couple. Electrochemical measurements indicate that in the presence of base, [H3(BArF3)2]− catalyzes the oxidation of H2. NMR evidence indicates dihydrogen bonding between these anionic hydrides and ammonium salts, which is relevant to the mechanism of hydrogenogenesis. In the case of Et4N[H3(BArF3)2], strong acids such as HCl induce H2 release to give the chloride Et4N[(CO)(CNBArF3)2Fe(pdt)(Cl)Ni(dppe)]. PMID:23899049

  18. Coordination Behavior of Ni2+, Cu2+, and Zn2+ in Tetrahedral 1-Methylimidazole Complexes: A DFT/CSD Study

    OpenAIRE

    Tetteh, Samuel

    2018-01-01

    The interaction between nickel (Ni2+), copper (Cu2+), and zinc (Zn2+) ions and 1-methylimidazole has been studied by exploring the geometries of eleven crystal structures in the Cambridge Structural Database (CSD). The coordination behavior of the respective ions was further investigated by means of density functional theory (DFT) methods. The gas-phase complexes were fully optimized using B3LYP/GENECP functionals with 6-31G∗ and LANL2DZ basis sets. The Ni2+ and Cu2+ complexes show distorted ...

  19. Syntheses, spectroscopic and thermal analyses of cyanide bridged heteronuclear polymeric complexes: [M(L)2Ni(CN)4]n (Ldbnd N-methylethylenediamine or N-ethylethylenediamine; Mdbnd Ni(II), Cu(II), Zn(II) or Cd(II))

    Science.gov (United States)

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla

    2016-02-01

    Polymeric tetracyanonickelate(II) complexes of the type [M(L)2Ni(CN)4]n (Ldbnd N-methylethylenediamine (men) or N-ethylethylenediamine (neen); Mdbnd Ni(II), Cu(II), Zn(II) or Cd(II)) have been prepared and characterized by FT-IR, Raman spectroscopy, thermal and elemental analysis techniques. Additionally, FT-IR and Raman spectral analyses of men and neen have experimentally and theoretically investigated in the range of 4000-250 cm-1. The corresponding vibration assignments of men and neen are performed by using B3LYP density functional theory (DFT) method together with 6-31 G(d) basis set. The spectral features of the complexes suggest that the coordination environment of the M(II) ions are surrounded by the two symmetry related men and neen ligands and the two symmetry related N atom of cyanide groups, whereas the Ni(II) atoms are coordinated with a square-planar to four C atoms of the cyanide groups. Polymeric structures of the complexes consist of one dimensional alternative chains of [M(L)2]2+ and [Ni(CN)4]2- moieties. The thermal decompositions in the temperature range 30-700 °C of the complexes were investigated in the static air atmosphere.

  20. Diffusion complex layers of TiC-Ni-Mo type produced on steel during vacuum titanizing process combined with the electrolytic deposition

    International Nuclear Information System (INIS)

    Kasprzycka, E.; Krolikowski, A.

    1999-01-01

    Diffusion carbide layers produced on steel surface by means of vacuum titanizing process have been studied. A new technological process combining a vacuum titanizing with an electrolytic deposition of Ni-Mo alloy has been proposed to increase of corrosion resistance of carbide layers. The effect of preliminary electrolytic deposition of Ni-Mo alloy on the NC10 steel surface on the titanized layer structure and its corrosion resistance has ben investigated. As a result, diffusion complex layers of TiC-Ni-Mo type on NC10 steel surface have been obtained. An X-ray structural analysis of titanized surfaces on NC10 steel precovered with an electrolytic Ni-Mo alloy coating (70%Ni+30%Mo) revealed a presence of titanium carbide TiC, NiTi, MoTi and trace quantity of austenite. The image of the TiC-Ni-Mo complex layer on NC10 steel surface obtained by means of joined SEM+TEM method and diagrams of elements distribution in the layer diffusion zone have been shown. Concentration of depth profiles of Ti, Ni, Mo, Cr and Fe in the layer diffusion zone obtained by means of the joined EDS+TEM method are shown. Concentration depth profiles of Ti, Ni, Mo, Cr and Fe in the layer diffusion zone obtained by means of the X r ay microanalysis and microhardness of the layer are shown. An X-ray structural analysis of titanized surfaces on the NC10 steel, without Ni-Mo alloy layer, revealed only a substantial presence of titanium carbide TiC. For corrosion resistance tests the steel samples with various diffusion layers and without layers were used: (i) the TiC-Ni-Mo titanized complex layers on NC10 steel, (ii) the TiC titanized carbide layers on the NC10 steel, (iii) the NC10 steel without layers. Corrosion measurements of sample under test have been performed in 0.1 M H 2 SO 4 by means of potentiodynamic polarization and electrochemical impedance tests. It has been found that the corrosion resistance of titanized steel samples with the TiC and TiC-Ni-Mo layers is higher than for the steel

  1. Correction: A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide.

    Science.gov (United States)

    Ng, Chee Koon; Wu, Jie; Hor, T S Andy; Luo, He-Kuan

    2016-12-22

    Correction for 'A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide' by Chee Koon Ng et al., Chem. Commun., 2016, 52, 11842-11845.

  2. Simulations of electrolytes at the liquid-liquid interface and of lanthanide cations complexes in gas phase

    International Nuclear Information System (INIS)

    Berny, F.

    2000-01-01

    Two processes related to liquid/liquid extraction of ions by extractant molecules were studied: the ion approach at the interface and the ion complexation by ligands. In the first part, the behaviour of salts at the chloroform/water interface was simulated by molecular dynamics. The aim was to understand the way these salts ions approach the interface in order to be extracted. Some ions are repelled by the interface (K + , Cl - , UO 2 2+ , Na + , NO 3 - ) whereas others adsorb (amphiphilic molecules and also ClO 4 - , SCN - , guanidinium Gu + and picrate Pic - ). The surface-active counter-ions make the ion approach at the interface easier. In a perfectly homogeneous mixture of the two solvents (water and chloroform) de-mixing, the ions seem to influence the phases separation rate. Nitric acid which is known to favour liquid/liquid extraction reveals strong adsorption at the interface in its neutral form and a smaller one in its ionic form (H 3 O + /NO 3 - ). HNO 3 and H 3 O + display particular orientations at the interface: hydrogen atoms are pointing in the direction of the water slab. The nature of the organic phase can also influence the ion approach at the interface. For example, Gu + and Pic - adsorb much less at the supercritical CO 2 /water interface than at the chloroform/water interface. In the second part, complexes of La 3+ , Eu 3+ and Yb 3+ with ligands such as amide, urea, thio-amide, thiourea were studied by quantum mechanics. Our calculations show that cation-ligand interactions depend on the nature of substituents on ligands, on the presence of counter-ions or on the number of ligands in the complex. Sulfur compounds seem to less interact with cations than oxygen compounds. Ureas interact as much as amides and are potentially good ligands. (author)

  3. Rietveld refinement of the crystal structures of Rb2XSi5O12 (X = Ni, Mn

    Directory of Open Access Journals (Sweden)

    Anthony M. T. Bell

    2016-02-01

    Full Text Available The synthetic leucite silicate framework mineral analogues Rb2XSi5O12 {X = Ni [dirubidium nickel(II pentasilicate] and Mn [dirubidium manganese(II pentasilicate]} have been prepared by high-temperature solid-state synthesis. The results of Rietveld refinements, using X-ray powder diffraction data collected using Cu Kα X-rays, show that the title compounds crystallize in the space group Pbca and adopt the cation-ordered structure of Cs2CdSi5O12 and other leucites. The structures consist of tetrahedral SiO4 and XO4 units sharing corners to form a partially substituted silicate framework. Extraframework Rb+ cations sit in channels in the framework. All atoms occupy the 8c general position for this space group. In these refined structures, silicon and X atoms are ordered onto separate tetrahedrally coordinated sites (T-sites. However, the Ni displacement parameter and the Ni—O bond lengths suggest that for the X = Ni sample, there may actually be some T-site cation disorder.

  4. Electronic structure of Co(III) doped bromo-bridged Ni complexes, [Ni1-xCox(chxn)2Br]Br2.

    Science.gov (United States)

    Xie, Jimin; Wu, Hashen; Kawakami, Daisuke; Iguchi, Hiroaki; Takaishi, Shinya; Yamashita, Masahiro; Matsuzaki, Hiroyuki; Okamoto, Hiroshi; Tanaka, Hisaaki; Kuroda, Shin-ichi

    2008-03-17

    This article describes the electronic structure of the Co(III) doped Br bridged Ni(III) complexes, [Ni(1-x)Cox(chxn)2Br]Br2 (x = 0.01, 0.02, 0.05, and 0.11) by using a optical spectroscopy, scanning tunneling microscopy (STM), and electron spin resonance spectroscopy. In the optical reflectivity spectrum, the new band was formed at about 0.5 eV, which is reasonably recognized as the d(z2) band of doped Co(III) ions. In the STM images of [Ni(1-x)Cox(chxn)2Br]Br2, the bright spots attributable to the tunnel current from the Fermi level of the STM tip to the conduction band of the sample were observed. In addition, some brighter spots were also observed. Because the number of the brighter spots is in good agreement with that of doped Co species, the brighter spots can be assigned to doped Co(III) sites. These are reasonably explained by the tunnel current from the Fermi level of the tip to the d(z2) band of Co(III). The Curie spin concentration was gradually increased with increasing Co(III) ions, which is explained by the scissions of the S = 1/2 1D antiferromagnetic chains.

  5. Association Mechanisms of Unsaturated C2 Hydrocarbons with Their Cations: Acetylene and Ethylene

    Science.gov (United States)

    Bera, Partha P.; Head-Gordon, Martin; Lee, Timothy J.

    2013-01-01

    The ion-molecule association mechanism of acetylene and ethylene with their cations is investigated by ab initio quantum chemical methods to understand the structures, association energies, and the vibrational and electronic spectra of the products. Stable puckered cyclic isomers are found as the result of first forming less stable linear and bridge isomers. The puckered cyclic complexes are calculated to be strongly bound, by 87, 35 and 56 kcal/mol for acetylene-acetylene cation, ethylene-ethylene cation and acetylene-ethylene cation, respectively. These stable complexes may be intermediates that participate in further association reactions. There are no association barriers, and no significant inter-conversion barriers, so the initial linear and bridge encounter complexes are unlikely to be observable. However, the energy gap between the bridged and cyclic puckered isomers greatly differs from complex to complex: it is 44 kcal/mol in C4H4 +, but only 6 kcal/mol in C4H8 +. The accurate CCSD(T) calculations summarized above are also compared against less computationally expensive MP2 and density functional theory (DFT) calculations for structures, relative energies, and vibrational spectra. Calculated vibrational spectra are compared against available experiments for cyclobutadiene cation. Electronic spectra are also calculated using time-dependent DFT.

  6. Cation-Inhibited Transport of Graphene Oxide Nanomaterials in Saturated Porous Media: The Hofmeister Effects.

    Science.gov (United States)

    Xia, Tianjiao; Qi, Yu; Liu, Jing; Qi, Zhichong; Chen, Wei; Wiesner, Mark R

    2017-01-17

    Transport of negatively charged nanoparticles in porous media is largely affected by cations. To date, little is known about how cations of the same valence may affect nanoparticle transport differently. We observed that the effects of cations on the transport of graphene oxide (GO) and sulfide-reduced GO (RGO) in saturated quartz sand obeyed the Hofmeister series; that is, transport-inhibition effects of alkali metal ions followed the order of Na + cations having large ionic radii (and thus being weakly hydrated) interacted with quartz sand and GO and RGO more strongly than did cations of small ionic radii. In particular, the monovalent Cs + and divalent Ca 2+ and Ba 2+ , which can form inner-sphere complexes, resulted in very significant deposition of GO and RGO via cation bridging between quartz sand and GO and RGO, and possibly via enhanced straining, due to the enhanced aggregation of GO and RGO from cation bridging. The existence of the Hofmeister effects was further corroborated with the interesting observation that cation bridging was more significant for RGO, which contained greater amounts of carboxyl and phenolic groups (i.e., metal-complexing moieties) than did GO. The findings further demonstrate that transport of nanoparticles is controlled by the complex interplay between nanoparticle surface functionalities and solution chemistry constituents.

  7. Cationic lipids: molecular structure/ transfection activity relationships and interactions with biomembranes.

    Science.gov (United States)

    Koynova, Rumiana; Tenchov, Boris

    2010-01-01

    Abstract Synthetic cationic lipids, which form complexes (lipoplexes) with polyanionic DNA, are presently the most widely used constituents of nonviral gene carriers. A large number of cationic amphiphiles have been synthesized and tested in transfection studies. However, due to the complexity of the transfection pathway, no general schemes have emerged for correlating the cationic lipid chemistry with their transfection efficacy and the approaches for optimizing their molecular structures are still largely empirical. Here we summarize data on the relationships between transfection activity and cationic lipid molecular structure and demonstrate that the transfection activity depends in a systematic way on the lipid hydrocarbon chain structure. A number of examples, including a large series of cationic phosphatidylcholine derivatives, show that optimum transfection is displayed by lipids with chain length of approximately 14 carbon atoms and that the transfection efficiency strongly increases with increase of chain unsaturation, specifically upon replacement of saturated with monounsaturated chains.

  8. Fascinating interaction of the ammonium cation with [2.2.2]paracyclophane: experimental and theoretical study

    Science.gov (United States)

    Makrlík, Emanuel; Sýkora, David; Böhm, Stanislav; Kvíčalová, Magdalena; Vaňura, Petr

    2018-05-01

    By means of electrospray ionisation mass spectrometry, it was evidenced experimentally that the ammonium cation (NH4+) reacts with the electroneutral [2.2.2]paracyclophane ligand (C24H24) to form the cationic complex [NH4(C24H24)]+. Moreover, applying quantum chemical calculations, the most probable conformation of the proven [NH4(C24H24)]+ complex was solved. In the complex [NH4(C24H24)]+ having a symmetry very close to C3, the 'central' cation NH4+ is coordinated by three strong bifurcated intramolecular hydrogen bonds to the corresponding six carbon atoms from the three benzene rings of [2.2.2]paracyclophane via cation-π interaction. Finally, the interaction energy, E(int), of the considered complex [NH4(C24H24)]+ was evaluated as -625.8 kJ/mol, confirming the formation of this fascinating complex species as well. It means that the [2.2.2]paracyclophane ligand can be considered as an effective receptor for the ammonium cation in the gas phase.

  9. Metal Complexation with Chitosan and its Grafted Copolymer

    International Nuclear Information System (INIS)

    Abo-Hussen, A.A.; Elkholy, S.S.; Elsabee, M.Z.

    2005-01-01

    The adsorption of M (II); Co (II), Ni (If), Cu (II), Zn (II) and Cd (II) from aqueous solutions by chitosan flakes and beads have been studied. The maximum up-take of M (II) ions on chitosan beads was greater than on flakes. Batch adsorption experiments were carried out as a function of ph, agitation period and initial concentration of the metal ions. A ph of 6.0 was found to be optimum for M (II) adsorption on chitosan flakes and beads. The uptake of the ions was determined from the changes in its concentration, as measured by ultraviolet and visible spectroscopy. The metal ions uptake of chitosan grafted with vinyl pyridine (VP) is higher than that of the chitosan. The experimental data of the adsorption equilibrium from M (II)-solutions correlated well with the Langmuir and Freundlich equations. Several spectroscopic methods have been used to study the formation of the polymer/metal cation complex. The cation coordination is accompanied by proton displacement off the polymer or by fixation of a hydroxide ion in aqueous solutions. The largest ionic displacement is observed with Cu (II) and Zn (II) demonstrating the largest affinity of chitosan for these ions. The FT-IR spectral of the complexes show that both the amino and hydroxyl groups of chitosan participated in the chelation process. The ESR spectra of Cu-complex show an absorption at gi 2.06, g// = 2.23, A// x 10-4 (cm-1) = 160 and G = 3.8 indicating the formation of square planar structure. The adsorption of M (II) ions followed the sequence Cu (II) > Zn (II) > Cd (II) > Ni (II) > Co (II), this order seems to be independent on the size and the physical form of chitosan. SEM shows small membranous structure on the surface of chitosan flakes as compared to Cu (Il)- chitosan complex. EDTA was used for the desorption studies

  10. Solvation of UCl{sub 6}{sup 2-} anionic complex by MeBu{sub 3}N{sup +}, BuMe{sub 2}Im{sup +} and BuMeIm{sup +} cations

    Energy Technology Data Exchange (ETDEWEB)

    Bosse, Emilie; Den Auwer, Christophe; Berthon, Claude; Guilbaud, Philippe; Moisy, Philippe [CEA Marcoule, DRCP/SCPS, BP 17171, 30207 Bagnols sur Ceze Cedex (France); Grigoriev, Mikhail S. [A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, RAS, Leninskii Prosp. 31, 119991 Moscow (Russian Federation); Nikitenko, Serguei [CNAB, UMR 5084, CNRS - Universite de Bordeaux 1, BP 120 Le Haut Vigneau, 33175 Gradignan Cedex (France); Le Naour, Claire; Cannes, Celine [IPN, UMR 8608, CNRS, Universite Paris-Sud, 91406 Orsay (France)

    2008-07-01

    The complexes [MeBu{sub 3}N]{sub 2}[UCl{sub 6}] and [BuMe{sub 2}Im]{sub 2}[UCl{sub 6}] were characterized in the solid state and in solution of [MeBu{sub 3}N][Tf{sub 2}N], [BuMe{sub 2}Im][Tf{sub 2}N] and [BuMeIm][Tf{sub 2}N] room temperature ionic liquids using single-crystal XRD, EXAFS, electrochemistry, UV-visible absorption spectroscopy and NMR. In the solid and in solution, the existence of hydrogen bonding between the anionic UCl{sub 6}{sup 2-} complex and the ionic liquid cations were revealed by these techniques. The MeBu{sub 3}N{sup +} cation interacts with UCl{sub 6}{sup 2-} via the protons on the alpha carbon atoms of nitrogen. The protons of the imidazolium ring account for the interaction between the BuMe{sub 2}Im+ cation and the UCl{sub 6}{sup 2-} anion. For the BuMeIm{sup +} cation the major interaction was confirmed between the most acidic proton on C(2) and UCl{sub 6}{sup 2-}. The experimental results also show that the intensity of the interaction between the UCl{sub 6}{sup 2-} anion and the cation varies with the ionic liquid cation in the following order: MeBu{sub 3}N{sup +} {approx} BuMe{sub 2}Im{sup +} << BuMeIm{sup +}. (authors)

  11. Remarkable fluorescence enhancement versus complex formation of cationic porphyrins on the surface of ZnO nanoparticles

    KAUST Repository

    Aly, Shawkat Mohammede

    2014-06-12

    Fluorescence enhancement of organic fluorophores shows tremendous potential to improve image contrast in fluorescence-based bioimaging. Here, we present an experimental study of the interaction of two cationic porphyrins, meso-tetrakis(1-methylpyridinium-4-yl)porphyrin chloride (TMPyP) and meso-tetrakis(4-N,N,N-trimethylanilinium)porphyrin chloride (TMAP), with cationic surfactant-stabilized zinc oxide nanoparticles (ZnO NPs) based on several steady-state and time-resolved techniques. We show the first experimental measurements demonstrating a clear transition from pronounced fluorescence enhancement to charge transfer (CT) complex formation by simply changing the nature and location of the positive charge of the meso substituent of the cationic porphyrins. For TMPyP, we observe a sixfold increase in the fluorescence intensity of TMPyP upon addition of ZnO NPs. Our experimental results indicate that the electrostatic binding of TMPyP with the surface of ZnO NPs increases the symmetry of the porphyrin macrocycle. This electronic communication hinders the rotational relaxation of the meso unit and/or decreases the intramolecular CT character between the cavity and the meso substituent of the porphyrin, resulting in the enhancement of the intensity of the fluorescence. For TMAP, on the other hand, the different type and nature of the positive charge resulting in the development of the CT band arise from the interaction with the surface of ZnO NPs. This observation is confirmed by the femtosecond transient absorption spectroscopy, which provides clear spectroscopic signatures of photoinduced electron transfer from TMAP to ZnO NPs. © 2014 American Chemical Society.

  12. Simulations of electrolytes at the liquid-liquid interface and of lanthanide cations complexes in gas phase; Simulations d'electrolytes a l'interface liquide/liquide et de complexes de cations lanthanides en phase gazeuse

    Energy Technology Data Exchange (ETDEWEB)

    Berny, F

    2000-07-01

    Two processes related to liquid/liquid extraction of ions by extractant molecules were studied: the ion approach at the interface and the ion complexation by ligands. In the first part, the behaviour of salts at the chloroform/water interface was simulated by molecular dynamics. The aim was to understand the way these salts ions approach the interface in order to be extracted. Some ions are repelled by the interface (K{sup +}, Cl{sup -}, UO{sub 2}{sup 2+}, Na{sup +}, NO{sub 3}{sup -}) whereas others adsorb (amphiphilic molecules and also ClO{sub 4}{sup -}, SCN{sup -}, guanidinium Gu{sup +} and picrate Pic{sup -}). The surface-active counter-ions make the ion approach at the interface easier. In a perfectly homogeneous mixture of the two solvents (water and chloroform) de-mixing, the ions seem to influence the phases separation rate. Nitric acid which is known to favour liquid/liquid extraction reveals strong adsorption at the interface in its neutral form and a smaller one in its ionic form (H{sub 3}O{sup +}/NO{sub 3}{sup -}). HNO{sub 3} and H{sub 3}O{sup +} display particular orientations at the interface: hydrogen atoms are pointing in the direction of the water slab. The nature of the organic phase can also influence the ion approach at the interface. For example, Gu{sup +} and Pic{sup -} adsorb much less at the supercritical CO{sub 2}/water interface than at the chloroform/water interface. In the second part, complexes of La{sup 3+}, Eu{sup 3+} and Yb{sup 3+} with ligands such as amide, urea, thio-amide, thiourea were studied by quantum mechanics. Our calculations show that cation-ligand interactions depend on the nature of substituents on ligands, on the presence of counter-ions or on the number of ligands in the complex. Sulfur compounds seem to less interact with cations than oxygen compounds. Ureas interact as much as amides and are potentially good ligands. (author)

  13. EXAFS analysis of cations distribution in structure of Co{sub 1−x}Ni{sub x}Fe{sub 2}O{sub 4} nanoparticles obtained by hydrothermal method in aloe vera extract solution

    Energy Technology Data Exchange (ETDEWEB)

    Wongpratat, Unchista [Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Maensiri, Santi [School of Physics, Institute of Science, Suranaree University, Nakhonratchasima 30000 (Thailand); Swatsitang, Ekaphan, E-mail: ekaphan@kku.ac.th [Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Integrated Nanotechnology Research Center, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 Thailand (Thailand)

    2016-09-01

    Graphical abstract: It is obvious from the M–H curves at room temperature of Co{sub 1−x}Ni{sub x}Fe{sub 2}O{sub 4} (x = 0, 0.25, 0.50, 0.75 and 1.0) nanoparticles that partially substitution of the lower Bohr magneton (2 μ{sub B}) and smaller atomic radii (0.55 Å at A site, 0.69 Å at B site) of Ni{sup 2+} ions on the higher Bohr magneton (3 μ{sub B}) and larger atomic radii (0.58 Å at A site, 0.74 Å at B site) of Co{sup 2+} ions can increase the saturation magnetization (M{sub s}) of sample with x = 0.75 to approximately 1.4 times of sample with x = 0, due to the increase of the aspect ratio (surface to volume) of nanoparticles, as a result of particle size decreasing from 37.03 to 12.63 nm. In addition to this, the ferrimagnetic behavior of CoFe{sub 2}O{sub 4} has been changed to superparamagnetic behavior with the dramatic decrease of the coercivity from 1365.60 to 63.15 Oe. - Highlights: • Magnetic behavior of Co{sub 1−x}Ni{sub x}Fe{sub 2}O{sub 4} NPs depends on Ni content and size of NPs. • Distribution of Co{sup 2+} and Ni{sup 2+} ions in the structure results in the increase of M{sub s}. • Superparamagnetic behavior is observed with increasing of the aspect ratio. • M{sub s} is increased by a factor 1.4 to a value of 57.57 emu/g in Co{sub 0.25}Ni{sub 0.75}Fe{sub 2}O{sub 4}. • H{sub c} is decreased by a factor 20 to a value of 63.15 Oe in Co{sub 0.25}Ni{sub 0.75}Fe{sub 2}O{sub 4}. - Abstract: Effect of cations distribution upon EXAFS analysis on magnetic properties of Co{sub 1−x}Ni{sub x}Fe{sub 2}O{sub 4} (x = 0, 0.25, 0.50, 0.75 and 1.0) nanoparticles prepared by the hydrothermal method in aloe vera extract solution were studied. XRD analysis confirmed a pure phase of cubic spinel ferrite of all samples. Changes in lattice parameter and particle size depended on the Ni content with partial substitution and site distributions of Co{sup 2+}, Ni{sup 2+} ions of different ionic radii at both tetrahedral and octahedral sites in the

  14. Bis[tris(propane-1,3-diamine-κ2N,N′nickel(II] diaquabis(propane-1,3-diamine-κ2N,N′nickel(II hexabromide dihydrate

    Directory of Open Access Journals (Sweden)

    Aymen Yangui

    2014-06-01

    Full Text Available In the title compound, [Ni(C3H10N23]2[Ni(C3H10N22(H2O2]Br6·2H2O, one Ni2+ cation, located on an inversion centre, is coordinated by four N atoms from two ligands and by two water O atoms. The other Ni2+ cation, located in a general position, is coordinated by six N atoms from three ligands. In both cases, the Ni2+ cation has an octahedral coordination environment. The overall structural cohesion is ensured by three types of hydrogen bonds, N—H...Br, O—H...Br and O—H...O, which connect the two types of complex cations, the bromide counter-anions and the lattice water molecules into a three-dimensional network.

  15. Cation-mediated conversion of the state of charge in uranium arene inverted-sandwich complexes

    Energy Technology Data Exchange (ETDEWEB)

    Camp, Clement; Mougel, Victor; Pecaut, Jacques; Mazzanti, Marinella [Laboratoire de Reconnaissance Ionique et Chimie de Coordination, SCIB, UMR-E3 CEA-UJF, INAC, CEA-Grenoble (France); Maron, Laurent [LCPNO, CNRS and INSA, UPS, Universite de Toulouse (France)

    2013-12-16

    Two new arene inverted-sandwich complexes of uranium supported by siloxide ancillary ligands [K{U(OSi(OtBu)_3)_3}{sub 2}(μ-η{sup 6}:η{sup 6}-C{sub 7}H{sub 8})] (3) and [K{sub 2}{U(OSi(OtBu)_3)_3}{sub 2}(μ-η{sup 6}:η{sup 6}-C{sub 7}H{sub 8})] (4) were synthesized by the reduction of the parent arene-bridged complex [{U(OSi(OtBu)_3)_3}{sub 2}(μ-η{sup 6}:η{sup 6}-C{sub 7}H{sub 8})] (2) with stoichiometric amounts of KC{sub 8} yielding a rare family of inverted-sandwich complexes in three states of charge. The structural data and computational studies of the electronic structure are in agreement with the presence of high-valent uranium centers bridged by a reduced tetra-anionic toluene with the best formulation being U{sup V}-(arene{sup 4-})-U{sup V}, KU{sup IV}-(arene{sup 4-})-U{sup V}, and K{sub 2}U{sup IV}-(arene{sup 4-})-U{sup IV} for complexes 2, 3, and 4 respectively. The potassium cations in complexes 3 and 4 are coordinated to the siloxide ligands both in the solid state and in solution. The addition of KOTf (OTf=triflate) to the neutral compound 2 promotes its disproportionation to yield complexes 3 and 4 (depending on the stoichiometry) and the U{sup IV} mononuclear complex [U(OSi(OtBu){sub 3}){sub 3}(OTf)(thf){sub 2}] (5). This unprecedented reactivity demonstrates the key role of potassium for the stability of these complexes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. From betaines to anionic N-heterocyclic carbenes. Borane, gold, rhodium, and nickel complexes starting from an imidazoliumphenolate and its carbene tautomer

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2016-12-01

    Full Text Available The mesomeric betaine imidazolium-1-ylphenolate forms a borane adduct with tris(pentafluorophenylborane by coordination with the phenolate oxygen, whereas its NHC tautomer 1-(2-phenolimidazol-2-ylidene reacts with (triphenylphosphinegold(I chloride to give the cationic NHC complex [Au(NHC2][Cl] by coordination with the carbene carbon atom. The anionic N-heterocyclic carbene 1-(2-phenolateimidazol-2-ylidene gives the complexes [K][Au(NHC−2], [Rh(NHC−3] and [Ni(NHC−2], respectively. Results of four single crystal analyses are presented.

  17. Watching proton transfer in real time: Ultrafast photoionization-induced proton transfer in phenol-ammonia complex cation.

    Science.gov (United States)

    Shen, Ching-Chi; Tsai, Tsung-Ting; Wu, Jun-Yi; Ho, Jr-Wei; Chen, Yi-Wei; Cheng, Po-Yuan

    2017-10-28

    In this paper, we give a full account of our previous work [C. C. Shen et al., J. Chem. Phys. 141, 171103 (2014)] on the study of an ultrafast photoionization-induced proton transfer (PT) reaction in the phenol-ammonia (PhOH-NH 3 ) complex using ultrafast time-resolved ion photofragmentation spectroscopy implemented by the photoionization-photofragmentation pump-probe detection scheme. Neutral PhOH-NH 3 complexes prepared in a free jet are photoionized by femtosecond 1 + 1 resonance-enhanced multiphoton ionization via the S 1 state. The evolving cations are then probed by delayed pulses that result in ion fragmentation, and the ionic dynamics is followed by measuring the parent-ion depletion as a function of the pump-probe delay time. By comparing with systems in which PT is not feasible and the steady-state ion photofragmentation spectra, we concluded that the observed temporal evolutions of the transient ion photofragmentation spectra are consistent with an intracomplex PT reaction after photoionization from the initial non-PT to the final PT structures. Our experiments revealed that PT in [PhOH-NH 3 ] + cation proceeds in two distinct steps: an initial impulsive wave-packet motion in ∼70 fs followed by a slower relaxation of about 1 ps that stabilizes the system into the final PT configuration. These results indicate that for a barrierless PT system, even though the initial PT motions are impulsive and ultrafast, the time scale to complete the reaction can be much slower and is determined by the rate of energy dissipation into other modes.

  18. Thermodynamic Study of the Complexation of p-Isopropylcalix[6]arene with Cs+ Cation in Dimethylsulfoxide-Acetonitrile Binary Media

    Directory of Open Access Journals (Sweden)

    Gholam Hossein Rounaghi

    2011-09-01

    Full Text Available The complexation reactions between the macrocyclic ionophore, p-isopropylcalix[6]arene and Cs+ cation were studied in dimethylsulfoxide–acetonitrile (DMSO-AN binary non-aqueous solvents at different temperatures using a conductometry method. The conductance data show that the stoichiometry of the (p-isopropylcalix[6]-arene·Cs+ complex in all binary mixed solvents is 1:1. The stability of the complexes is affected by the composition of the binary solvent media and a non-linear behavior was observed for changes of log Kf of the complex versus the composition of the binary mixed solvents. The thermodynamic parameters (DH°c and DS°c for formation of (p-isopropyl-calix[6]arene·Cs+ complex were obtained from temperature dependence of the stability constant and the obtained results show that the (p-isopropylcalix[6]arene·Cs+ complex is enthalpy destabilized, but entropy stabilized, and the values of the mentioned parameters are affected strongly by the nature and composition of the binary mixed solvents.

  19. How easy is CO2 fixation by M-C bond containing complexes (M = Cu, Ni, Co, Rh, Ir)?

    KAUST Repository

    Nolan, Steve; Cavallo, Luigi; Poater, Albert; Vummaleti, Sai V. C.; Talarico, Giovanni

    2015-01-01

    A comparison between different M–C bonds (M = Cu(I), Ni(II), Co(I), Rh(I) and Ir(I)) has been reported by using density functional theory (DFT) calculations to explore the role of the metal in the fixation or incorporation of CO2 into such complexes. The systems investigated are various metal based congeners of the Ir-complex 8 [(cod)(IiPr)Ir-CCPh], with a ligand scaffold based on cod and IiPr ligands (cod = 1,5-cyclooctadiene; IiPr = 1,3-bis(isopropyl)imidazol-2-ylidene). The results of this study show that the calculated CO2 insertion barriers follow the trend: Cu(I) (20.8 kcal mol−1) < Rh(I) (30.0 kcal mol−1) < Co(I) (31.3 kcal mol−1) < Ir(I) (37.5 kcal mol−1) < Ni(II) (45.4 kcal mol−1), indicating that the Cu(I) based analogue is the best CO2 fixer, while Ni(II) is the worst in the studied series.

  20. How easy is CO2 fixation by M-C bond containing complexes (M = Cu, Ni, Co, Rh, Ir)?

    KAUST Repository

    Nolan, Steve

    2015-11-27

    A comparison between different M–C bonds (M = Cu(I), Ni(II), Co(I), Rh(I) and Ir(I)) has been reported by using density functional theory (DFT) calculations to explore the role of the metal in the fixation or incorporation of CO2 into such complexes. The systems investigated are various metal based congeners of the Ir-complex 8 [(cod)(IiPr)Ir-CCPh], with a ligand scaffold based on cod and IiPr ligands (cod = 1,5-cyclooctadiene; IiPr = 1,3-bis(isopropyl)imidazol-2-ylidene). The results of this study show that the calculated CO2 insertion barriers follow the trend: Cu(I) (20.8 kcal mol−1) < Rh(I) (30.0 kcal mol−1) < Co(I) (31.3 kcal mol−1) < Ir(I) (37.5 kcal mol−1) < Ni(II) (45.4 kcal mol−1), indicating that the Cu(I) based analogue is the best CO2 fixer, while Ni(II) is the worst in the studied series.

  1. Influence of Cu, Co and Ni cations incorporated in brucite-type layers on thermal behaviour of hydrotalcites and reducibility of the derived mixed oxide systems

    Energy Technology Data Exchange (ETDEWEB)

    Chmielarz, Lucjan; Kustrowski, Piotr; Rafalska-Lasocha, Alicja; Dziembaj, Roman

    2002-01-03

    Thermal decomposition of M-Mg-Al-CO{sub 3}-NO{sub 3} hydrotalcites (where M is Cu{sup 2+}, Co{sup 2+} or Ni{sup 2+}) with intended M/Mg (0.10/0.61) and M/Al (0.10/0.29) ratios prepared under the same conditions was studied using high temperature X-ray diffraction (HT-XRD) and thermogravimetry coupling with mass spectrometry (TGA-DTA-MS). Introduction of transition metals to the brucite-like layers of hydrotalcites changed their thermal behaviour. The decomposition of nitrate or carbonate anions was coupled with oxidation from Ni{sup 2+} to Ni{sup 3+} and Co{sup 2+} to Co{sup 3+}. Further increase of temperature resulted in reduction of these cations. Reduction from Cu{sup 2+} to Cu{sup +} was also observed above 700 deg. C. Stabilisation of carbonate anions by Cu{sup 2+} introduced into hydrotalcite matrix was found at temperatures above 600 deg. C. The thermal treatment of hydrotalcite precursors resulted in the formation of mixed oxide and spinel phases, which were stable after cooling to ambient temperature with exception of CuO phase that appeared during cooling down due to segregation effects. Reducibility of the hydrotalcites calcined at different temperatures was determined by temperature-programmed reduction (TPR) experiments. Specific surface areas of hydrotalcites calcined at 600 deg. C ranged from 226 to 196 m{sup 2}/g dropping with increase in the calcination temperatures to values ranging between 138 and 49 m{sup 2}/g depending on transition metal contents.

  2. Optimizing cationic and neutral lipids for efficient gene delivery at high serum content.

    Science.gov (United States)

    Chan, Chia-Ling; Ewert, Kai K; Majzoub, Ramsey N; Hwu, Yeu-Kuang; Liang, Keng S; Leal, Cecília; Safinya, Cyrus R

    2014-01-01

    Cationic liposome (CL)-DNA complexes are promising gene delivery vectors with potential application in gene therapy. A key challenge in creating CL-DNA complexes for application is that their transfection efficiency (TE) is adversely affected by serum. In particular, little is known about the effects of a high serum content on TE, even though this may provide design guidelines for application in vivo. We prepared CL-DNA complexes in which we varied the neutral lipid [1,2-dioleoyl-sn-glycerophosphatidylcholine, glycerol-monooleate (GMO), cholesterol], the headgroup charge and chemical structure of the cationic lipid, and the ratio of neutral to cationic lipid; we then measured the TE of these complexes as a function of serum content and assessed their cytotoxicity. We tested selected formulations in two human cancer cell lines (M21/melanoma and PC-3/prostate cancer). In the absence of serum, all CL-DNA complexes of custom-synthesized multivalent lipids show high TE. Certain combinations of multivalent lipids and neutral lipids, such as MVL5(5+)/GMO-DNA complexes or complexes based on the dendritic-headgroup lipid TMVLG3(8+) exhibited high TE both in the absence and presence of serum. Although their TE still dropped to a small extent in the presence of serum, it reached or surpassed that of benchmark commercial transfection reagents, particularly at a high serum content. Two-component vectors (one multivalent cationic lipid and one neutral lipid) can rival or surpass benchmark reagents at low and high serum contents (up to 50%, v/v). We propose guidelines for optimizing the serum resistance of CL-DNA complexes based on a given cationic lipid. Copyright © 2014 John Wiley & Sons, Ltd.

  3. Complexation of biological ligands with lanthanides(III) for MRI: Structure, thermodynamic and methods; Complexation des cations lanthanides trivalents par des ligands d'origine biologique pour l'IRM: Structure, thermodynamique et methodes

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet, C

    2006-07-15

    New cyclic ligands derived from sugars and amino-acids form a scaffold carrying a coordination sphere of oxygen atoms suitable to complex Ln(III) ions. In spite of their rather low molecular weights, the complexes display surprisingly high relaxivity values, especially at high field. The ACX and BCX ligands, which are acidic derivatives of modified and cyclo-dextrins, form mono and bimetallic complexes with Ln(III). The LnACX and LnBCX complexes show affinities towards Ln(III) similar to those of tri-acidic ligands. In the bimetallic Lu2ACX complex, the cations are deeply embedded in the cavity of the ligand, as shown by the X-ray structure. In aqueous solution, the number of water molecules coordinated to the cation in the LnACX complex depends on the nature and concentration of the alkali ions of the supporting electrolyte, as shown by luminescence and relaxometric measurements. There is only one water molecule coordinated in the LnBCX complex, which enables us to highlight an important second sphere contribution to relaxivity. The NMR study of the RAFT peptidic ligand shows the complexation of Ln(III), with an affinity similar to those of natural ligands derived from calmodulin. The relaxometric study also shows an important second sphere contribution to relaxivity. To better understand the intricate molecular factors affecting relaxivity, we developed new relaxometric methods based on probe solutes. These methods allow us to determine the charge of the complex, weak affinity constants, trans-metallation constants, and the electronic relaxation rate. (author)

  4. Phosphorus dendrimers and photodynamic therapy. Spectroscopic studies on two dendrimer-photosensitizer complexes: Cationic phosphorus dendrimer with rose bengal and anionic phosphorus dendrimer with methylene blue.

    Science.gov (United States)

    Dabrzalska, Monika; Zablocka, Maria; Mignani, Serge; Majoral, Jean Pierre; Klajnert-Maculewicz, Barbara

    2015-08-15

    Dendrimers due to their unique architecture may play an important role in drug delivery systems including chemotherapy, gene therapy and recently, photodynamic therapy as well. We investigated two dendrimer-photosensitizer systems in context of potential use of these systems in photodynamic therapy. The mixtures of an anionic phosphorus dendrimer of the second generation and methylene blue were studied by UV-vis spectroscopy while that of a cationic phosphorus dendrimer (third generation) and rose bengal were investigated by spectrofluorimetric methods. Spectroscopic analysis of these two systems revealed the formation of dendrimer-photosensitizer complexes via electrostatic interactions as well as π stacking. The stoichiometry of the rose bengal-cationic dendrimer complex was estimated to be 7:1 and 9:1 for the methylene blue-anionic dendrimer complex. The results suggest that these polyanionic or polycationic phosphorus dendrimers can be promising candidates as carriers in photodynamic therapy. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Cationic uremic toxins affect human renal proximal tubule cell functioning through interaction with the organic cation transporter.

    Science.gov (United States)

    Schophuizen, Carolien M S; Wilmer, Martijn J; Jansen, Jitske; Gustavsson, Lena; Hilgendorf, Constanze; Hoenderop, Joost G J; van den Heuvel, Lambert P; Masereeuw, Rosalinde

    2013-12-01

    Several organic cations, such as guanidino compounds and polyamines, have been found to accumulate in plasma of patients with kidney failure due to inadequate renal clearance. Here, we studied the interaction of cationic uremic toxins with renal organic cation transport in a conditionally immortalized human proximal tubule epithelial cell line (ciPTEC). Transporter activity was measured and validated in cell suspensions by studying uptake of the fluorescent substrate 4-(4-(dimethylamino)styryl)-N-methylpyridinium-iodide (ASP(+)). Subsequently, the inhibitory potencies of the cationic uremic toxins, cadaverine, putrescine, spermine and spermidine (polyamines), acrolein (polyamine breakdown product), guanidine, and methylguanidine (guanidino compounds) were determined. Concentration-dependent inhibition of ASP(+) uptake by TPA, cimetidine, quinidine, and metformin confirmed functional endogenous organic cation transporter 2 (OCT2) expression in ciPTEC. All uremic toxins tested inhibited ASP(+) uptake, of which acrolein required the lowest concentration to provoke a half-maximal inhibition (IC50 = 44 ± 2 μM). A Dixon plot was constructed for acrolein using three independent inhibition curves with 10, 20, or 30 μM ASP(+), which demonstrated competitive or mixed type of interaction (K i = 93 ± 16 μM). Exposing the cells to a mixture of cationic uremic toxins resulted in a more potent and biphasic inhibitory response curve, indicating complex interactions between the toxins and ASP(+) uptake. In conclusion, ciPTEC proves a suitable model to study cationic xenobiotic interactions. Inhibition of cellular uptake transport was demonstrated for several uremic toxins, which might indicate a possible role in kidney disease progression during uremia.

  6. The effect of Ni on concentration of the most abundant essential cations in several Brassica species

    Directory of Open Access Journals (Sweden)

    Putnik-Delić Marina I.

    2014-01-01

    Full Text Available Some plants from the genus Brassica have the ability to tolerate excessive concentrations of heavy metals, including Ni. Considering the fact that Ni is a very toxic element for living beings we wanted to examine its influence on some species from genus Brassicaceae. The aim of this study was to investigate the effect of Ni on distribution and accumulation of essential macronutrients from the standpoint of food quality and phytoremediation potential. Experiments were performed using winter (W and spring (S varieties of rapeseed (Brassica napus, L., white mustard (Brassica alba, L., black mustard (Brassica nigra, L. and turnip (Brassica rapa, L.. The seeds were exposed to 10 μM Ni from the beginning of germination. Plants were grown in water cultures, in semi-controlled conditions of a greenhouse, on ½ strength Hoagland solution to which was added Ni in the same concentration as during germination. Concentrations and distribution of Ca, Mg, K in leaf and stem were altered in the presence of increased concentration of Ni. Significant differences were found between the control and Ni-treated plants as well as among the genotypes. [Projekat Ministarstva nauke Republike Srbije, br. TR 31036 i br. TR 31016

  7. Behavior of cesium and thallium cations inside a calixarene cavity as probed by nuclear spin relaxation. Evidence of cation-pi interactions in water.

    Science.gov (United States)

    Cuc, Diana; Bouguet-Bonnet, Sabine; Morel-Desrosiers, Nicole; Morel, Jean-Pierre; Mutzenhardt, Pierre; Canet, Daniel

    2009-08-06

    We have studied the complexes formed between the p-sulfonatocalix[4]arene and cesium or thallium metal cation, first by carbon-13 longitudinal relaxation of the calixarene molecule at two values of the magnetic field B(0). From the longitudinal relaxation times of an aromatic carbon directly bonded to a proton, thus subjected essentially to the dipolar interaction with that proton, we could obtain the correlation time describing the reorientation of the CH bond. The rest of this study has demonstrated that it is also the correlation time describing the tumbling of the whole calixarene assembly. From three non-proton-bearing carbons of the aromatic cycles (thus subjected to the chemical shift anisotropy and dipolar mechanisms), we have been able to determine the variation of the chemical shift anisotropy when going from the free to the complex form of the calixarene. These variations not only provide the location of the cation inside the calixarene cavity but also constitute a direct experimental proof of the cation-pi interactions. These results are complemented by cesium and thallium relaxation measurements performed again at two values of the magnetic field B(0). An estimation of the mean distance between the cation and the calixarene protons could be obtained. These measurements have also revealed an important chemical shift anisotropy of thallium upon complexation.

  8. Interaction of Cr (III), Ni (II), Pb (II) with DTPA complexes of essential metal ions

    International Nuclear Information System (INIS)

    Gulzar, S.; Zahida; Maqsood, T.; Naqvi, R.R.

    2002-01-01

    With the increase of anthropogenic activities in the environment, heavy metal toxicity (Chromium, Nickel and Lead) is more common now. DTPA (diethylene triamine pentaacetic acid) a polyamino carboxylic acid is widely used to form hydrophilic and stable complexes with most of the metal ions. In this spectrophotometric study, concentration of Cr(III), Ni(II) and Pb(II) (toxic metal ions) exchanged with Fe(III), Zn(II) and Ca(II) from their DTPA complexes were estimated at pH 4,7 and 9. Concentration of added metal was varied from 1-4 times to that of complexed metal. (author)

  9. Spectroscopic evaluation of Co(II), Ni(II) and Cu(II) complexes derived from thiosemicarbazone and semicarbazone

    Science.gov (United States)

    Chandra, Sulekh; Kumar, Anil

    2007-12-01

    Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L 1) and semicarbazone (L 2) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L) 2(SO 4) and Cu(L) 2(SO 4) [where L = L 1 and L 2] which are of five coordinated square pyramidal geometry.

  10. Synthesis, characterization, structure and properties of heterobimetallic complexes [CuNi(μ-OAc) (μ-OH) (μ-OH2) (bpy)2] (BF4)2 and [CuNi(bz)3(bpy)2] ClO4 from 2,2‧ bipyridine

    Science.gov (United States)

    Kurbah, Sunshine D.; Kumar, A.; Syiemlieh, I.; Dey, A. K.; Lal, R. A.

    2018-02-01

    Heterobimetallic complexes of the composition [CuNi(bpy)2 (μ-OAc) (μ-OH) (μ-OH2)](BF4)2 (1) and [CuNi(bz)3 (bpy)2]ClO4 (2) were synthesized in moderate yield through solid state reaction and have been characterized by elemental analyses, molar conductance, mass spectra, magnetic moment, EPR, UV-Vis, IR spectroscopies and cyclic voltammetry. The ground state in complex (1) is doublet while that in complex (2), the ground state is a mixture of doublet and quartet, respectively. The structure of the complexes has been established by X-ray crystallography. The electron transfer reactions of the complexes have been investigated by cyclic voltammetry.

  11. Relationship between the supramolecular structure and the transfection efficiency for cationic micelle/DNA complexes

    International Nuclear Information System (INIS)

    Sakuragi, Mina; Kusuki, Shota; Hamada, Emi; Sakurai, Kazuo; Masunaga, Hiroyasu; Sasaki, Sono

    2009-01-01

    We synthesized a cationic lipid benzyl amine derivative bearing a primary amine as the head group and evaluated its transfection efficiency as a DNA carrier. A lipoplex (complex of DNA and lipid micelle) was prepared by mixing BA and two neutral colipids (DOPE and DLPC). When we compared the transfection efficiency at various compositions, we found that B-lipoplex (BA/DOPE/DLPC=1/2/1) was the most efficient while A-lipoplex (BA/DLPC=1/1) showed no transfection. We compared A-lipoplex with B-lipoplex by use of SAXS, fluorescence spectrum of ethidium bromide and pyrene. These results indicated that A-lipoplex formed a lamellar or cylinder structure within which DNA molecules were trapped in the lipid alkyl chain, while B-lipoplex formed cylinders where DNAs were intercalated between the lipid micelle cylinders. (author)

  12. Nanoscale encapsulation: the structure of cations in hydrophobic microporous aluminosilicates

    International Nuclear Information System (INIS)

    Wasserman, S.R.; Yuchs, S.E.; Giaquinta, D.; Soderholm, L.; Song, Kang.

    1996-01-01

    Hydrophobic microporous aluminosilicates, created by organic surface modification of inherently hydrophilic materials such as zeolites and clays, are currently being investigated as storage media for hazardous cations. Use of organic monolayers to modify the surface of an aluminosilicate after introducing an ion into the zeolite/clay reduces the interaction of water with the material. Resulting systems are about 20 times more resistant to leaching of stored ion. XAS spectra from the encapsulated ion demonstrate that byproducts from the organic modifier can complex with the stored cation. This complexation can result in a decreased affinity of the cation for the aluminosilicate matrix. Changing the organic modifier eliminates this problem. XAS spectra also indicate that the reactivity and speciation of the encapsulated ion may change upon application of the hydrophobic layer

  13. Synthesis and Crystal Structures of Luminescent Mononuclear Ni(ii and Cd(ii Complexes with 1,10-phenanthroline

    Directory of Open Access Journals (Sweden)

    Ecaterina Tocana

    2017-12-01

    Full Text Available New supramolecular systems of Ni(II and Cd(II with 1,10-phenanthroline constructed by non-covalent interactions have been synthesized and characterized by single-crystal X-ray diffractometry. The smaller nickel(II ion forms a cis complex with outer-sphere perchlorates, while the cadmium(II ion forms a trans complex involving inner-sphere perchlorates. Both compoundsrevealintraligand-basedluminescentproperties.

  14. Quantum transport behavior of Ni-based dinuclear complexes in presence of zigzag graphene nanoribbon as electrode

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Sunandan; Pramanik, Anup; Sarkar, Pranab, E-mail: pranab.sarkar@visva-bharati.ac.in

    2016-10-20

    Highlights: • Quantum transport properties of some Ni-based dinuclear complexes are investigated. • The materials show various spin dependent properties like NDR, spin filtering, etc. • These are occurred by the influence of edge states of zGNR. • Proper tuning of these materials can alter these phenomena. - Abstract: Quantum transport properties of some Ni-based dinuclear complexes with different polydentate organic ligands have been studied by applying abinitio density functional theory along with nonequilibrium Green’s function formulations. It is demonstrated that these materials are capable of showing multifunctional spin dependent properties by the influence of edge states of zigzag edged graphene nanoribbons. The current–voltage characteristics of these materials show spin dependent negative differential resistance behavior, spin filtering effect, and also voltage rectifying property. Proper tuning of these materials can alter these effects which may be utilized in various spintronic devices.

  15. Complejidad, conflicto armado y vulnerabilidad de niños y niñas desplazados en colombia (complexity, armed conflict, and vulnerability of displaced children in colombia

    Directory of Open Access Journals (Sweden)

    Jose Alonso Andrade Salazar

    2014-12-01

    Full Text Available RESUMEN: Este trabajo tiene como objetivo realizar una reflexión acerca de la vulnerabilidad de los niños y niñas víctimas del conflicto armado en Colombia. Para ello se recurriro al principio de auto-eco-organización y de Bucle inter-retroactivo. La violencia es un fenómeno complejo de múltiples interacciones, de características no-lineales y tendencia auto-eo-organizativa que afecta la noción de sujeto y altera el modo como los niños y niñas interpretan el mundo y sus interacciones. ABSTRACT: This paper aims to carry out a reflection on the vulnerability of children, who are victims of the armed conflict in Colombia. This was used at the beginning of the self-eco-organization and the inter-retroactive loop. Violence is a complex phenomenon of multiple interactions, non-linear features, and a self-ecoorganizational tendency, which affects the notion of subject and alters the way that children interpret the world and their interactions.

  16. Synthesis, characterization and anti-fungal evaluation of Ni(II and Cu(II complexes with a derivative of 4-aminoantipyrine

    Directory of Open Access Journals (Sweden)

    Monika Tyagi

    2017-01-01

    Full Text Available Transition metal complexes of Ni(II and Cu(II metal ions with the general stoichiometry [M(LX]X and [M(LSO4], where M = Ni(II and Cu(II, L = (1E-N-((5-((E-(2,3-dimethyl-1-phenyl-4-pyrazolineiminomethylthiophen-2-ylmethylene-2,3-dimethyl-1-phenyl-4-pyrazolineamine and X = Cl−, NO3− and SO42−, have been synthesized and characterized. The synthesized ligand and metal complexes were characterized by 1H NMR, IR, mass spectrometry, UV–Vis spectra and EPR. In molecular modelling, the geometries of the Schiff's base and metal complexes were fully optimized with respect to the energy using the 6-31g(d,p basis set. The nickel(II complexes were found to have octahedral geometry, whereas the copper(II complexes were of tetragonal geometry. The covalency factor (β and orbital reduction factor (k suggest the covalent nature of the complexes. To develop broad spectrum new molecules against seed-borne fungi, the minimum inhibitory concentration (MIC of the ligand and its metal complexes was evaluated by the serial dilution method.

  17. Examination of the effect of the annealing cation on higher order structures containing guanine or isoguanine repeats

    Science.gov (United States)

    Pierce, Sarah E.; Wang, Junmei; Jayawickramarajah, Janarthanan; Hamilton, Andrew D.; Brodbelt, Jennifer S.

    2010-01-01

    Isoguanine (2-oxo-6-amino-guanine), a natural but non-standard base, exhibits unique self-association properties compared to its isomer, guanine, and results in formation of different higher order DNA structures. In this work, the higher order structures formed by oligonucleotides containing guanine repeats or isoguanine repeats after annealing in solutions containing various cations are evaluated by electrospray ionization mass spectrometry (ESI-MS) and circular dichroism (CD) spectroscopy. The guanine-containing strand (G9) consistently formed quadruplexes upon annealing, whereas the isoguanine strand (Ig9) formed both pentaplexes and quadruplexes depending on the annealing cation. Quadruplex formation with G9 showed some dependence on the identity of the cation present during annealing with high relative quadruplex formation detected with six of ten cations. Analogous annealing experiments with Ig9 resulted in complex formation with all ten cations, and the majority of the resulting complexes were pentaplexes. CD results indicated most of the original complexes survived the desalting process necessary for ESI-MS analysis. In addition, several complexes, especially the pentaplexes, were found to be capable of cation exchange with ammonium ions. Ab initio calculations were conducted for isoguanine tetrads and pentads coordinated with all ten cations to predict the most energetically stable structures of the complexes in the gas phase. The observed preference of forming quadruplexes versus pentaplexes as a function of the coordinated cation can be interpreted by the calculated reaction energies of both the tetrads and pentads in combination with the distortion energies of tetrads. PMID:19746468

  18. Synthesis and characterization of sodium cation-conducting Nax(MyL1-yO2 (M = Ni2+, Fe3+; L = Ti4+, Sb5+

    Directory of Open Access Journals (Sweden)

    Marques, F. M. B.

    2004-06-01

    Full Text Available The Na+-conducting ceramics of layered Na0.8Ni0.4Ti0.6O2, Na0.8Fe0.8Ti0.2O2, Na0.8Ni0.6Sb0.4O2 (structural type O3 and Na0.68Ni0.34Ti0.66O2 (P2 type with density higher than 91% were prepared via the standard solid-state synthesis route and characterized by the impedance spectroscopy, thermal analysis, scanning electron microscopy, structure refinement using X-ray powder diffraction data, measurements of Na+ concentration cell e.m.f., and dilatometry. The conductivity of antimonate Na0.8Ni0.6Sb0.4O2, synthesized first time, was found lower than that of isostructural Na0.8Ni0.4Ti0.6O2 due to larger ion jump distance between Na+ sites. At temperatures above 420 K, transport properties of sodium cationconducting materials are essentially independent of partial water vapor pressure. In the low-temperature range, the conductivity reversibly increases with water vapor pressure varied in the range from approximately 0 (dry air up to 0.46 atm. The sensitivity to air humidity is influenced by the ceramic microstructure, being favored by increasing boundary area. The average thermal expansion coefficients of layered materials at 300-1173 K are in the range (13.7-16.0×10-6 K-1.Se han preparado cerámicas conductoras conteniendo Na+ de composición Na0.8Ni0.4Ti0.6O2, Na0.8Fe0.8Ti0.2O2, Na0.8Ni0.6Sb0.4O2 (tipo estructural O3 y Na0.68Ni0.34Ti0.66O2 (tipo P2 con densidad mayor del 91%. Las vía de preparación fu la ruta de estandard de síntesis en estado sólido. Las composiciones se caracterizaron mediante espectroscopía de impedancia, análisis térmico, microscopía electrónica de barrido, refinamiento de la estructura usando datos de difracción de rayos X en polvo, medidas de concentración de Na+, f.e.m. de la célula y dilatometría. La conductividad del antimoniate, sintetizado por primera vez, Na0.8Ni0.6Sb0.4O2, era menor que la del compuesto isoestructural Na0.8Ni0.4Ti0.6O2 debido a la mayor distancia de salto iónico entre las posiciones de Na

  19. Removal of cobalt, chromium, copper, iron and nickel cations from electroplating waste water by apatite ore

    Energy Technology Data Exchange (ETDEWEB)

    Kargar-Razi, M.; Yahyaabadi, S. [Azad Univ. Tehran (Iran, Islamic Republic of)

    2012-07-01

    In this investigation, the adsorption behavior of natural phosphate rock and it's concentrate with respect to Fe{sup 3+}, Ni{sup 2+}, Co{sup 2+}, Cu{sup 2+} and Cr{sup 3+} has been studied, in order to consider its application to purity of electroplating waste water pollution. The batch mehtod has been employed, using metal concentrations in solution ranging from 2 ppm to 40 ppm with mixing process. The effect of pH, concentration of heavy metals and times (10-20 min) is considered. The results of their removal performance in 40 ppm concentration, pH = 8 and 10 minutes are obtained as Cr{sup 3+} > Cu{sup 2+} > Fe{sup 3+} > Co{sup 2+} > Ni{sup 2+} for phosphate rock and the sequence can be given as Cr{sup 3+} > Fe{sup 3+} > Cu{sup 2+} > Co{sup 2+} > Ni{sup 2+} for phosphate concentrate. It was found that the adsorption phenomena depend on charge density and hydrated ion diameter. The same results show that maximum adsorption in PH = 4.5 and 7 for concentrate. The Langmuir adsorption isotherm constants corresponding to adsorption capacity were found to be as Cr{sup 3+} > Fe{sup 3+} > Cu{sup 2+} > Ni{sup 2+} > Co{sup 2+} for phosphate soil and Cr{sup 3+} > Fe{sup 3+} > Cu{sup 2+} > Co{sup 2+} > Ni{sup 2+} for phosphate concentrate. Sorption of metallic cations are considered in pH 4.5, 7 and 8. The results show that phosphate rock and its concentrate have great potential to remove cations of heavy metal species from electroplating waste water. (orig.)

  20. Study of complex formation between C18H36N2O6 and UO22+ cation in some binary mixed non-aqueous solutions

    Directory of Open Access Journals (Sweden)

    G.H. Rounaghi

    2017-02-01

    Full Text Available The complexation reaction between UO22+ cation and the macrobicyclic ligand C18H36N2O6 was studied in acetonitrile–dimethylformamide (AN–DMF, acetonitrile–tetrahydrofuran (AN–THF, acetonitrile–dichloromethane (AN–DCM binary solvent solutions at different temperatures using the coductometric method. In most cases, C18H36N2O6 forms a 1:1 [M:L] complex with the UO22+ cation. But in some of the studied solvent systems, in addition to formation of a 1:1 complex, a 1:2 [M:L2] complex is formed in solution. A non-linear behavior was observed for changes of logKf of the (C18H36N2O6·UO22+ complex versus the composition of the binary mixed solvents. The sequence of the stability of the (C18H36N2O6·UO22+ complex in pure solvent systems at 25 °C decreases in the order: AN > THF > DMF. In the case of binary solvent solutions, the stability constant of the complex at 25 °C was found to be: AN–DCM > AN–THF > AN–DMF. The values of thermodynamic quantities (ΔSc°,ΔHc°, for the formation of the complex were obtained from temperature dependence of the stability constant of the complex using the van't Hoff plots. The results show that in all cases, the complex is both entropy and enthalpy stabilized and both of these parameters are affected by the nature and composition of the mixed solvent systems.

  1. Thermodynamic study on the complexation of Trivalent actinide and lanthanide cation by N-donor ligands in homogeneous conditions; Etude thermodynamique de la complexation des ions actinide (III) et lanthanide (III) par des ligands polyazotes en milieu homogene

    Energy Technology Data Exchange (ETDEWEB)

    Miguirditchian, M

    2004-07-01

    Polydentate N-donor ligands, alone or combined with a synergic acid, may selectively extract minor actinides(III) from lanthanide(III) ions, allowing to develop separation processes of long-live radioelements. The aim of the researches carried out during this thesis was to better understand the chemical mechanisms of the complexation of f-elements by Adptz, a tridentate N-donor ligand, in homogeneous conditions. A thermodynamic approach was retained in order to estimate, from an energetic point of view, the influence of the different contributions to the reaction, and to acquire a complete set of thermodynamic data on this reaction. First, the influence of the nature of the cation on the thermodynamics was considered. The stability constants of the 1/1 complexes were systematically determined by UV-visible spectrophotometry for every lanthanide ion (except promethium) and for yttrium in a mixed solvent methanol/water in volume proportions 75/25%. The thermodynamic parameters ({delta}H{sup 0} {delta}{sup S}) of complexation were estimated by the van't Hoff method and by micro-calorimetry. The trends of the variations across the lanthanide series are compared with similar studies. The same methods were applied to the study of three actinide(III) cations: plutonium, americium and curium. The comparison of these values with those obtained for the lanthanides highlights the increase of stability of these complexes by a factor of 20 in favor of the actinide cations. This gap is explained by a more exothermic reaction and is associated, in the data interpretation, to a higher covalency of the actinide(III)-nitrogen bond. Then, the influence of the change of solvent composition on the thermodynamic of complexation was studied. The thermodynamic parameters of the complexation of europium(III) by Adptz were determined for several fractions of methanol. The stability of the complex formed increases with the percentage of methanol in the mixed solvent, owing to an

  2. Cation effects on phosphatidic acid monolayers at various pH conditions.

    Science.gov (United States)

    Zhang, Ting; Cathcart, Matthew G; Vidalis, Andrew S; Allen, Heather C

    2016-10-01

    The impact of pH and cations on phase behavior, stability, and surface morphology for dipalmitoylphosphatidic acid (DPPA) monolayers was investigated. At pHCations are found to expand and stabilize the monolayer in the following order of increasing magnitude at pH 5.6: Na + >K + ∼Mg 2+ >Ca 2+ . Additionally, cation complexation is tied to the pH and protonation state of DPPA, which are the primary factors controlling the monolayer surface behavior. The binding affinity of cations to the headgroup and thus deprotonation capability of the cation, ranked in the order of Ca 2+ >Mg 2+ >Na + >K + , is found to be well explained by the law of matching water affinities. Nucleation of surface 3D lipid structures is observed from Ca 2+ , Mg 2+ , and Na + , but not from K + , consistent with the lowest binding affinity of K + . Unraveling cation and pH effects on DPPA monolayers is useful in further understanding the surface properties of complex systems such as organic-coated marine aerosols where organic films are directly influenced by the pH and ionic composition of the underlying aqueous phase. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  3. Radiation damage buildup and dislocation evolution in Ni and equiatomic multicomponent Ni-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Levo, E. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Granberg, F., E-mail: fredric.granberg@helsinki.fi [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Fridlund, C.; Nordlund, K. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Djurabekova, F. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Helsinki Institute of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland)

    2017-07-15

    Single-phase multicomponent alloys of equal atomic concentrations (“equiatomic”) have proven to exhibit promising mechanical and corrosion resistance properties, that are sought after in materials intended for use in hazardous environments like next-generation nuclear reactors. In this article, we investigate the damage production and dislocation mobility by simulating irradiation of elemental Ni and the alloys NiCo, NiCoCr, NiCoFe and NiFe, to assess the effect of elemental composition. We compare the defect production and the evolution of dislocation networks in the simulation cells of two different sizes, for all five studied materials. We find that the trends in defect evolution are in good agreement between the different cell sizes. The damage is generally reduced with increased alloy complexity, and the dislocation evolution is specific to each material, depending on its complexity. We show that increasing complexity of the alloys does not always lead to decreased susceptibility to damage accumulation under irradiation. We show that, for instance, the NiCo alloy behaves very similarly to Ni, while presence of Fe or Cr in the alloy even as a third component reduces the saturated level of damage substantially. Moreover, we linked the defect evolution with the dislocation transformations in the alloys. Sudden drops in defect number and large defect fluctuations from the continuous irradiation can be explained from the dislocation activity.

  4. Cation-enhanced capillary electrophoresis separation of atropoisomer anions.

    Science.gov (United States)

    Na, Yun-Cheol; Berthod, Alain; Armstrong, Daniel W

    2015-12-01

    CE was used to study the separation of the atropoisomers of four phosphoric acids and two sulfonic acids and the enantiomers of two phosphoric acids. All solutes are in their anionic forms in aqueous electrolytes. The chiral additives were two hydroxypropyl cyclodextrins (CDs) and cyclofructan 6 (CF6). The CDs were able to separate four solutes and the CF6 additive could separate only one: 1,1'-binaphthyl-2,2'-diyl hydrogenphosphate (BHP). Since CF6 is able to bind with cations, nitrate of alkaline metals, Ba(2+) , and Pb(2+) were added, greatly improving the BHP separation at the expense of longer migration times. There seems to be a link between CF6-cation-binding constants and BHP resolution factors. Cation additions were also performed with CD selectors that are less prone to form complexes with cations. Significant improvements of enantiomer or atropoisomer separations were observed also associated with longer migration times. It is speculated that the anionic solutes associate with the added cations forming larger entities better differentiated by CDs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. A cationic Agi( PNPtBu) species acting as PNP transfer agent: facile synthesis of Pd(PNPtBu)(alkyl) complexes and their reactivity compared to PCPtBu analogues

    NARCIS (Netherlands)

    Vlugt, van der J.I.; Siegler, M.A.; Janssen, M.C.C.; Vogt, D.; Spek, A.L.

    2009-01-01

    The straightforward synthesis of cationic complex 1, [Ag(PNPtBu)]BF4 (PNPtBu = 1,2-bis[(di-tert-butylphosphino)methyl]pyridine), and its facile transmetalating properties toward gold and palladium are described. The corresponding Au complex [Au(PNPtBu)]2(BF4)2 (2) exists as a dimer in the solid

  6. Hydrological Response and Complex Impact Pathways of the 2015/2016 El Niño in Eastern and Southern Africa

    Science.gov (United States)

    Siderius, C.; Gannon, K. E.; Ndiyoi, M.; Opere, A.; Batisani, N.; Olago, D.; Pardoe, J.; Conway, D.

    2018-01-01

    The 2015/2016 El Niño has been classified as one of the three most severe on record. El Niño teleconnections are commonly associated with droughts in southern Africa and high precipitation in eastern Africa. Despite their relatively frequent occurrence, evidence for their hydrological effects and impacts beyond agriculture is limited. We examine the hydrological response and impact pathways of the 2015/2016 El Niño in eastern and southern Africa, focusing on Botswana, Kenya, and Zambia. We use in situ and remotely sensed time series of precipitation, river flow, and lake levels complemented by qualitative insights from interviews with key organizations in each country about awareness, impacts, and responses. Our results show that drought conditions prevailed in large parts of southern Africa, reducing runoff and contributing to unusually low lake levels in Botswana and Zambia. Key informants characterized this El Niño through record high temperatures and water supply disruption in Botswana and through hydroelectric load shedding in Zambia. Warnings of flood risk in Kenya were pronounced, but the El Niño teleconnection did not materialize as expected in 2015/2016. Extreme precipitation was limited and caused localized impacts. The hydrological impacts in southern Africa were severe and complex, strongly exacerbated by dry antecedent conditions, recent changes in exposure and sensitivity and management decisions. Improved understanding of hydrological responses and the complexity of differing impact pathways can support design of more adaptive, region-specific management strategies.

  7. Colloid, adhesive and release properties of nanoparticular ternary complexes between cationic and anionic polysaccharides and basic proteins like bone morphogenetic protein BMP-2.

    Science.gov (United States)

    Petzold, R; Vehlow, D; Urban, B; Grab, A L; Cavalcanti-Adam, E A; Alt, V; Müller, M

    2017-03-01

    Herein we describe an interfacial local drug delivery system for bone morphogenetic protein 2 (BMP-2) based on coatings of polyelectrolyte complex (PEC) nanoparticles (NP). The application horizon is the functionalization of bone substituting materials (BSM) used for the therapy of systemic bone diseases. Nanoparticular ternary complexes of cationic and anionic polysaccharides and BMP-2 or two further model proteins, respectively, were prepared in dependence of the molar mixing ratio, pH value and of the cationic polysaccharide. As further proteins chymotrypsin (CHY) and papain (PAP) were selected, which served as model proteins for BMP-2 due to similar isoelectric points and molecular weights. As charged polysaccharides ethylenediamine modified cellulose (EDAC) and trimethylammonium modified cellulose (PQ10) were combined with cellulose sulphatesulfate (CS). Mixing diluted cationic and anionic polysaccharide and protein solutions according to a slight either anionic or cationic excess charge colloidal ternary dispersions formed, which were cast onto germanium model substrates by water evaporation. Dynamic light scattering (DLS) demonstrated, that these dispersions were colloidally stable for at least one week. Fourier Transform Infrared (FTIR) showed, that the cast protein loaded PEC NP coatings were irreversibly adhesive at the model substrate in contact to HEPES buffer and solely CHY, PAP and BMP-2 were released within long-term time scale. Advantageously, out of the three proteins BMP-2 showed the smallest initial burst and the slowest release kinetics and around 25% of the initial BMP-2 content were released within 14days. Released BMP-2 showed significant activity in the myoblast cells indicating the ability to regulate the formation of new bone. Therefore, BMP-2 loaded PEC NP are suggested as novel promising tool for the functionalization of BSM used for the therapy of systemic bone diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Bimetallic ruthenium complexes bridged by divinylphenylene bearing oligo(ethylene glycol)methylether: synthesis, (spectro)electrochemistry and the lithium cation effect.

    Science.gov (United States)

    Tian, Li Yan; Liu, Yuan Mei; Tian, Guang-Xuan; Wu, Xiang Hua; Li, Zhen; Kou, Jun-Feng; Ou, Ya-Ping; Liu, Sheng Hua; Fu, Wen-Fu

    2014-03-14

    A series of 1,4-disubstituted ruthenium-vinyl complexes, (E,E)-[{(PMe3)3(CO)ClRu}2(μ-HC=CH-Ar-CH=CH)], in which the 1,4-diethenylphenylene bridge bears two oligo(ethylene glycol)methyl ether side chains at different positions (2,5- and 2,3-positions), were prepared. The respective products were characterized by elemental analyses and NMR spectroscopy. The structures of complexes 1b and 1e were established by X-ray crystallography. The electronic properties of the complexes were investigated by cyclic voltammetry, and IR and UV-vis/NIR spectroscopies. Electrochemical studies showed that the 2,5-substituents better stabilized the mixed-valence states; the electrochemical behavior was greatly affected by lithium cations, especially complex 1g with 2,3-substituents, which was further supported by IR and UV-vis/NIR spectra changes. Spectroelectrochemical studies showed that the redox chemistry was dominated by the non-innocent character of the bridging fragment.

  9. Environmentally-relevant concentrations of Al(III) and Fe(III) cations induce aggregation of free DNA by complexation with phosphate group.

    Science.gov (United States)

    Qin, Chao; Kang, Fuxing; Zhang, Wei; Shou, Weijun; Hu, Xiaojie; Gao, Yanzheng

    2017-10-15

    Environmental persistence of free DNA is influenced by its complexation with other chemical species and its aggregation mechanisms. However, it is not well-known how naturally-abundant metal ions, e.g., Al(III) and Fe(III), influence DNA aggregation. This study investigated aggregation behaviors of model DNA from salmon testes as influenced by metal cations, and elucidated the predominant mechanism responsible for DNA aggregation. Compared to monovalent (K + and Na + ) and divalent (Ca 2+ and Mg 2+ ) cations, Al(III) and Fe(III) species in aqueous solution caused rapid DNA aggregations. The maximal DNA aggregation occurred at 0.05 mmol/L Al(III) or 0.075 mmol/L Fe(III), respectively. A combination of atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy revealed that Al(III) and Fe(III) complexed with negatively charged phosphate groups to neutralize DNA charges, resulting in decreased electrostatic repulsion and subsequent DNA aggregation. Zeta potential measurements and molecular computation further support this mechanism. Furthermore, DNA aggregation was enhanced at higher temperature and near neutral pH. Therefore, DNA aggregation is collectively determined by many environmental factors such as ion species, temperature, and solution pH. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Magnetic studies on Layered solid solution Lix(Ni0.4Mn0.6)2-xO2

    Science.gov (United States)

    Nakao, K.; Nakamura, T.; Yamada, Y.; Koshiba, N.

    2011-05-01

    Lix(Ni0.4Mn0.6)2-xO2 (1.09hydroxide as raw materials. All the compounds have a layered rock-salt structure, and the cation mixing degree (Ni2+ occupancy in the Li-layer) decreases with an increase in x. From the low-temperature magnetic measurement, they all have negative Weiss temperature and spontaneous magnetization, that is, they are ferromagnetic materials. Both the Curie temperature and the spontaneous magnetization at 4.2K decrease with an increase in x. These magnetic variations are attributed to the lowering of the cation mixing degree: the magnetic interaction network turns to two-dimensional one with the loss of the inert-layer coupling. These situations may be considered semi-quantitatively using the ferromagnetic cluster model. Additionally, the cation mixing degree has an influence on their electrochemical properties such as cycle fading and rate capability.

  11. Alkaline cation complexing with calixarenes in electro-spray / mass spectrometry. Specificity for cesium, influence of solvation on ion species and radiolytic stability of the complexing media

    International Nuclear Information System (INIS)

    Allain, Francoise

    2000-01-01

    Radioactive waste management is a rather difficult issue. In order to reduce the volume of waste storage, particularly the Cs 135 (radioactive half-life 2.3 10 6 years), liquid-liquid extraction experiments have shown that crown calixarenes were able to selectively extract cesium cation in wastes. However, the stability under radiolysis of this type of macrocycle is unknown and is the theme of this thesis. Through the coupling of electro-spray and mass spectrometry, the selectivity of crown calixarenes for cesium has been confirmed. The necessity to optimize operating conditions during the utilization of this ionization mode was acknowledged for a correct interpretation of mass spectrum. The solvent nature, source temperature, applied voltage on the cone, gaseous phase stability and species ionization desorption rate are indeed parameters that should be taken into account. Experiments show that the solution species stability is inverse to the one in gaseous phase. In a solution, species stability is linked to the nature of the solvent (solvating power) whereas in gaseous phase, it is linked to the cationic affinity. In the current radiolysis conditions it has been demonstrated that calixarenes have a stable structure. Degradation products are very largely substitution products and do not hinder the caesium cation complexing. Concerning the quantitative aspect, an estimation was produced, however results are not satisfying: reference product synthesis is in fact necessary in order to establish calibration curves that will allow to precisely dose the various components derived from radiolysis [fr

  12. Effects of cation substitution on thermal expansion and electrical properties of lanthanum chromites

    International Nuclear Information System (INIS)

    Ding Xifeng; Liu Yingjia; Gao Ling; Guo Lucun

    2006-01-01

    The effects of cation substitution on the sintering characteristics, thermal expansion and electrical conductivity properties of La(AE)Cr(M)O 3 (AE=Mg, Ca, Sr, M=Ni, Cu, Co) were investigated. The sinterability of alkaline metal earth (AE)-doped LaCrO 3 increased with AE contents in a sequence of Ca > Sr > Mg. Sr-doped LaCrO 3 sample had a TEC compatible with that of 8YSZ electrolyte. The transition metals of Ni, Co and Cu substituted in Cr-site further optimized the sinterability of La 0.85 Sr 0.15 CrO 3 in air. Ni and Co could effectively enhance the electrical conductivity from room temperature to 1123 K though the concomitant increase in TEC was distinctively large with Co doping. The TEC was controlled by co-doping Ni and Co in Cr-site, and La 0.85 Sr 0.15 Cr 0.95 Ni 0.02 Co 0.02 O 3 exhibited a TEC of 10.9 x 10 -6 /K, which was matched with that of 8YSZ, indicating that it could be suitable to be used as an SOFC interconnect material

  13. Studies on some VO(IV, Ni(II and Cu(II complexes of non-symmetrical tetradentate Schiff-bases

    Directory of Open Access Journals (Sweden)

    Aderoju A. Osowole

    2008-08-01

    Full Text Available The coordination chemistry of VO(IV, Ni(II and Cu(II with unsymmetrical Schiff base ligands, [HO(OCH3C6H3C(CH3:N(CH2CH2N:C(CH3CH:C(C6H5OH], H2L and [HO(OCH3C6H3C(CH3:N(CH2CH2N:C(CH3CH:C(CH3OH], H2L1 (derived from condensation of 1-phenyl-1,3-butanedione/2,4-pentanedione, ethylenediamine and 5-methoxy-2-hydroxy acetophenone is discussed. The metal complexes were characterized by elemental analysis, molar conductance, magnetic susceptibility, infrared and electronic spectral measurements. They are magnetically dilute, non-electrolytes in nitromethane. The ligands are tetradentately coordinating via the imine N and enolic O atoms, resulting in 5-coordinate square-pyramidal geometry for the VO(IV complexes and 4-coordinate square-planar geometry for the Ni(II and Cu(II complexes. The assignment of geometry is supported by magnetic and spectral measurements.

  14. Study of the chemical interactions of actinide cations in solution at macroscopic concentrations

    International Nuclear Information System (INIS)

    Maurice, C.

    1983-01-01

    The aim of this work was to study the interactions of pentavalent neptunium in dodecane-diluted tributyl phosphate with other metallic cations, especially uranium VI and ruthenium present in reprocessing solutions. Pentavalent neptunium on its own was shown to exist in several forms complexed by water and TBP and also to dimerise. In the complex it forms with uranium VI the interaction via the neptunyl oxygen is considerably enhanced in organic solution. Dibutyl phosphoric acid strengthens the interaction between neptunium and uranium. The Np V-ruthenium interaction reveals the existence of a new cation-cation complex; the process takes place in two successive stage and leads to the formation, reinforced and accelerated by HDBP, of a highly to the formation, reinforced and accelerated by HDBP, of a highly stable complex. These results contribute towards a better knowledge of the behaviour of neptunium in the reprocessing operation [fr

  15. Structural, Magnetic and Microwave Properties of Nanocrystalline Ni-Co-Gd Ferrites

    Science.gov (United States)

    Nikzad, Alireza; Parvizi, Roghaieh; Rezaei, Ghasem; Vaseghi, Behrooz; Khordad, Reza

    2018-02-01

    A series of Co- and Gd-substituted NiFe2O4 ferrite nanoparticles with the formula Ni1- x Co x Fe2- y Gd y O4 (where x = 0.0-1.0 and y = 0.0-0.1) have been successfully synthesized using a hydrothermal method. X-ray diffraction and field emission scanning electron microscopy results indicated that a highly crystallized spherical ferrite nanoparticle structure was obtained along with an increase in the lattice parameters. Compositional analysis of the prepared nanoferrite powders has been carried out using energy-dispersive x-ray (EDX) spectra. The EDX analysis reveals the presence of Ni, Co, Gd and Fe elements in the specimens. Magnetization and the coercive field improved dramatically with an increase in the amount of cobalt and gadolinium added, attributed to the redistribution of cations in the spinel nanoferrite structure. Saturation magnetization and coercivity values up to 99 emu/g and 918 Oe, respectively, were measured using a vibration sample magnetometer at room temperature. Comparative microwave absorption experiments demonstrated that the reflection loss (RL) properties enhanced with increasing substitution of cations in the Ni-ferrite spinel structure for an absorber thickness of 1.8 mm. A maximum RL of - 26.7 dB was obtained for substituted Ni-Co-Gd nanoferrite with x = 1.0 and y = 0.1 at a frequency of 9.4 GHz with a bandwidth of 3.6 GHz (RL ≤ - 10 dB). Experimental results revealed that the synthesized nanoparticles possessed great potential in microwave absorption applications.

  16. Inorganic and organic structures as interleavers among [bis(1-methyl-3-(p-carboxylatephenyl)triazenide 1-oxide)Ni(II)] complexes to form supramolecular arrangements

    Science.gov (United States)

    Santos, Aline Joana Rolina Wohlmuth Alves; dos Santos Hackbart, Helen Cristina; Giacomini, Gabriela Xavier; Bersch, Patrícia; Paraginski, Gustavo Luiz; Hörner, Manfredo

    2016-12-01

    Alternative compounds to capture metal ions are triazenes 1-oxide since they are basic compounds O(N) with negative charge in the deprotonated form. The proximity of both coordination sites (O and N) enables these compounds to have good chelating ability and a tendency to stabilize in the formation of rings with soft and hard transition metal ions. The structure analysis by single crystal X-ray diffraction of compounds (1) and (2) demonstrate the formation of 3D supramolecular arrangements through ion-ion, ion-dipolo and dipolo-dipolo interactions. In one of them, there are [(H2O)2(CH3CH3SO)K2]2+ as linkers of polymerization and, in another complex, there are [(H2O)(CH3CH3SO)Ni(H2O)6]2+ as a linker of polymerization. These linkers act in the polymerization of the novel mononuclear complex [bis(1-methyl (p-carboxylatephenyl) triazenide 1-oxide) NiII] (3). The crystallography analysis of (1) and (2) showed distorted quadratic geometry for Ni (II), thus, there are two axial positions available in Ni (II) to be used in catalysis studies and as sensor or biosensor. In addition, this study shows the support of this novel mononuclear complex of Ni (II) (3) on protonated chitosan chains (4). The compounds (3) and (4) were characterized by spectroscopic analysis, infrared (IR) and energy dispersive X-ray detector (EDS), and by differential scanning calorimetry analysis (DSC). The specificity of ligand 1-methyl (p-carboxyphenyl) triazene 1-oxide to capture potassium and nickel ions will be tested at different pH values, as well as the capacity of the triazenide 1-oxide of Ni (II) complex, supported on chitosan polymer, or not, to act as a catalyst for organic reactions and biomimetic organic reactions.

  17. Metal cation controls phosphate release in the myosin ATPase.

    Science.gov (United States)

    Ge, Jinghua; Huang, Furong; Nesmelov, Yuri E

    2017-11-01

    Myosin is an enzyme that utilizes ATP to produce a conformational change generating a force. The kinetics of the myosin reverse recovery stroke depends on the metal cation complexed with ATP. The reverse recovery stroke is slow for MgATP and fast for MnATP. The metal ion coordinates the γ phosphate of ATP in the myosin active site. It is accepted that the reverse recovery stroke is correlated with the phosphate release; therefore, magnesium "holds" phosphate tighter than manganese. Magnesium and manganese are similar ions in terms of their chemical properties and the shell complexation; hence, we propose to use these ions to study the mechanism of the phosphate release. Analysis of octahedral complexes of magnesium and manganese show that the partial charge of magnesium is higher than that of manganese and the slightly larger size of manganese ion makes its ionic potential smaller. We hypothesize that electrostatics play a role in keeping and releasing the abstracted γ phosphate in the active site, and the stronger electric charge of magnesium ion holds γ phosphate tighter. We used stable myosin-nucleotide analog complex and Raman spectroscopy to examine the effect of the metal cation on the relative position of γ phosphate analog in the active site. We found that in the manganese complex, the γ phosphate analog is 0.01 nm further away from ADP than in the magnesium complex. We conclude that the ionic potential of the metal cation plays a role in the retention of the abstracted phosphate. © 2017 The Protein Society.

  18. Synthesis, Characterization and Antimicrobial Activity of Cu(II, Co(II and Ni(II Complexes with O, N, and S Donor Ligands

    Directory of Open Access Journals (Sweden)

    Vidyavati Reddy

    2008-01-01

    Full Text Available The complexes of the type ML2 [where M = Cu(II, Co(II, and Ni(II] L = 1-phenyl-1-ene-3-(2-hydroxyphenyl-prop-2-ene with 3- substituted-5-mercapto-4-amino-1,2,4-triazoles. Schiff base ligands have been prepared by reacting 3-(2-hydroxyphenyl-1-phenylprop-2-en-1-one and 3-phenyl/pyridyl-4-amino-5-mercapto-1,2,4-triazoles in an alcoholic medium. The complexes are non-electrolytes in DMF. The resulting complexes were characterized by elemental analysis, magnetic measurements, conductivity measurements and spectral studies. The Schiff base acts as a tridentate dibasic and coordinating through the deprotonated oxygen, thioenolic sulphur and azomethine nitrogen atoms. It is found that Cu(II, Co(II, and Ni(II complexes exhibited octahedral geometry. The antimicrobial activities of ligands and its complexes were screened by cup plate method.

  19. Metalophthalocyanine complexes as ion-carriers in membrane-selective electrodes for detection of thiosalicylic acid

    International Nuclear Information System (INIS)

    Shahrokhian, Saeed; Souri, Ali

    2004-01-01

    The potentiometric response properties of several PVC-based membrane electrodes using phthalocyanine complexes of aluminum (AlPc), nickel (NiPc) and copper (CuPc) as anion carriers, toward thiosalicylic acid (TSA) were investigated. The influences of lipophilic ionic additives (cationic and anionic) and the pH of the buffered solutions were used for the interpretation of the mechanism of the potentiometric response of sensors. The sensitivity, linear range, detection limit, and potentiometric selectivity of the membrane sensors show a considerable dependence on the nature of central metal of the ionophore. The membrane electrodes based on AlPc demonstrate sub-Nernstian responses toward TSA over the range of 0.01 to 1x10 -5 M. In the case of NiPc and CuPc as ionophores and in the presence of trioctylmethyl ammonium (TOMA + ) as a cationic additive, a Nernstian response could be established in a range of 4 orders of magnitudes of TSA concentration (0.01 to 1x10 -6 M). The results of potentiometric investigations revealed that from thermodynamic point of view, the axial coordination of thiosalicylate with the central metal of NiPc and CuPc is more efficient with respect to AlPc. This preference in response to TSA was discussed on the basis of the softness nature of NiPc and CuPc and more affinity for coordination with the thiolate group of thiosalicylate as a soft anion. These potentiometric sensors manifest prominent advantages of high selectivity for TSA over the various inorganic and organic anions, fast response times and micromolar detection limits and can be used over a wide pH range of 4.0-8.0. The prepared electrodes based on NiPc and CuPc were successfully applied in the potentiometric titration of sub-milimolar quantities of Hg 2+ in aqueous solutions and very good recovery results were obtained in these measurements. The results of complexometric studies between Hg 2+ and TSA using electrodes based on NiPc and CuPc as indicator electrodes were compared with

  20. New Mn(II, Ni(II, Cd(II, Pb(II complexes with 2-methylbenzimidazole and other ligands. Synthesis, spectroscopic characterization, crystal structure, magnetic susceptibility and biological activity studies

    Directory of Open Access Journals (Sweden)

    Shayma A. Shaker

    2016-11-01

    Full Text Available Synthesis and characterization of Mn(II, Ni(II, Cd(II and Pb(II mixed ligand complexes of 2-methylbenzimidazole with other ligands have been reported. The structure of the ligands and their complexes was investigated using elemental analysis, IR, UV–Vis, (1H, 13C NMR spectroscopy, molar conductivity and magnetic susceptibility measurements. In all the studies of complexes, the 2-methylbenzimidazole behaves as a neutral monodentate ligand which is coordinated with the metal ions through the N atom. While benzotriazole behaves as a neutral bidentate ligand which is coordinated with the Ni(II ion through the two N atoms. Moreover, the N-acetylglycine behaves as a bidentate ligand which is coordinated with the Mn(II, Ni(II and Pb(II ions through the N atom and the terminal carboxyl oxygen atom. The magnetic and spectral data indicate the tetrahedral geometry for Mn(II complex, irregular tetrahedral geometry for Pb(II complex and octahedral geometry for Ni(II complex. The X-ray single crystal diffraction method was used to confirm a centrosymmetric dinuclear Cd(II complex as each two metal ions are linked by a pair of thiocyanate N = S bridge. Two 2-methylbenzimidazole N-atom donors and one terminal thiocyanate N atom complete a highly distorted square pyramid geometry around the Cd atom. Besides, different cell types were used to determine the inhibitory effect of Mn(II, Ni(II, Cd(II and Pb(II complexes on cell growth using MTT assay. Cd(II complex showed cytotoxic effect on various types of cancer cell lines with different EC50 values.

  1. Solvent extraction behavior of several elements with long chain amines in the presence of thiourea as a complexing agent

    International Nuclear Information System (INIS)

    Abrao, A.

    1976-01-01

    The solvent estraction behaviour of U, Fe, Cd, In, Zn, Cu, Co, Ni, Mn, Cr, Ag, Bi, Pb, Tl, Ru, Rh, Pd, Pt, Ir, Os, Au, Hg, Sn, and Sb with tri-n-octylamine diluted with benzene, xylene, varsol and methyl-isobutyl-cetone from HCl, HNO 3 , H 2 SO 4 and HI is investigated. The effect of thiourea as a complexing ligand, giving rise to unextracted cationic species of several metallic ions and its consequence in the extraction by the amine is described. The effect of an acidified thiourea solution for scribbing the organic phase is studied as well. It is demonstrated that the stable cationic metal-thiourea complexes are not extracted. The study confirms that the extraction mechanisms is an ion exchange association between the protonated amine and the extracted anionic species. Special emphasis is given to the uranium extraction and its decontamination from several elements. Applications of the new technique are described [pt

  2. Preparation of 64Cu based on nuclear reaction of 64Ni (p,n) 64Cu: Simulations of target preparation and radionuclidic separation

    International Nuclear Information System (INIS)

    Sunarhadijoso Soenarjo; Wira Y Rahman; Sriyono; Triyanto

    2010-01-01

    As a preliminary study for production technology of 64 Cu based on nuclear reaction of 64 Ni (p,n) 64 Cu, the nickel targets were prepared by electroplating method using acidic solution of nickel chloride - boric acid and basic solution of nickel sulphate - nickel chloride mixtures on a silver-surfaced target holder. The simulated solution of Ni(II) - Cu(II) matrix was considered as the solution of post-proton-irradiated nickel containing radioactive copper. In the presented work the irradiation of nickel target was omitted, while the radioactive copper was obtained from neutron irradiation of CuO target. The separation of radioactive copper was based on anion exchange column chromatography in which the radiocopper was conditioned to form CuCl 4 2- anion complex, while the nickel was kept as Ni 2+ cation. It was found that the electroplating deposit from the acidic solution was better than that form the basic solution. By conditioning the matrix solution in 6 M HCl, the radioactive copper was indicated in the forms of Cu 2+ and CuCl 4 2- while the nickel was in the form of Ni 2+ . In the condition of 9 M HCl, the radioactive copper was in the form of CuCl 4 2- , while the nickel was found as both Ni 2+ and CuCl 4 2- . The best condition of separation was in 8 M HCl in which the radioactive copper was in the form of CuCl 4 2- , while the nickel was in the form of Ni 2+ . The retained CuCl 4 2- was then changed back into Cu 2+ cation and eluted out from the column by using 0.05 M HCl. The γ-spectrometric analysis showed a single strong peak at 511 keV in accordance to γ-annihilation peak coming from positron decay of 64 Cu, and a very weak peak at 1346 keV related to γ-ray from internal energy transition of 64 Cu. (author)

  3. Study of complexation process between 4'-nitrobenzo-15-crown-5 and yttrium(III) cation in binary mixed non-aqueous solvents using conductometric method

    Science.gov (United States)

    Habibi, N.; Rounaghi, G. H.; Mohajeri, M.

    2012-12-01

    The complexation reaction of macrocyclic ligand (4'-nitrobenzo-15C5) with Y3+ cation was studied in acetonitrile-methanol (AN-MeOH), acetonitrile-ethanol (AN-EtOH), acetonitrile-dimethylformamide (AN-DMF) and ethylacetate-methanol (EtOAc-MeOH) binary mixtures at different temperatures using conductometry method. The conductivity data show that in all solvent systems, the stoichiometry of the complex formed between 4'-nitrobenzo-15C5 and Y3+ cation is 1: 1 (ML). The stability order of (4'-nitrobenzo-15C5). Y3+ complex in pure non-aqueous solvents at 25°C was found to be: EtOAc > EtOH > AN ≈ DMF > MeOH, and in the case of most compositions of the binary mixed solvents at 25°C it was: AN≈MeOH ≈ AN-EtOH > AN-DMF > EtOAc-MeOH. But the results indicate that the sequence of the stability of the complex in the binary mixed solutions changes with temperature. A non-linear behavior was observed for changes of log K f of (4'-nitrobenzo-15C5 · Y3+) complex versus the composition of the binary mixed solvents, which was explained in terms of solvent-solvent interactions and also the hetero-selective solvation of the species involved in the complexation reaction. The values of thermodynamic parameters (Δ H {c/ℴ} and Δ S {c/ℴ}) for formation of the complex were obtained from temperature dependent of the stability constant using the van't Hoff plots. The results represent that in most cases, the complex is both enthalpy and entropy stabilized and the values and also the sign of thermodynamic parameters are influenced by the nature and composition of the mixed solvents.

  4. Structural chemistry and magnetic properties of Pr3-xSr1+xCrNiO8

    International Nuclear Information System (INIS)

    Dutton, Sian E.; Bahout, Mona; Battle, Peter D.; Tonus, Florent; Demange, Valerie

    2008-01-01

    Polycrystalline samples of the n=1 Ruddlesden-Popper system Pr 3-x Sr 1+x CrNiO 8 have been synthesized over the composition range 0.0 0.1 adopt the tetragonal space group I4/mmm; Pr 2.9 Sr 1.1 CrNiO 8 adopts the orthorhombic space group Fmmm. There is no evidence of Cr/Ni cation ordering in any composition. A maximum in the zero-field cooled magnetic susceptibility is observed at a temperature T f that decreases with increasing Sr content; 52≤T f (K)≤13. The frequency dependence of T f observed in a.c. susceptibility measurements, together with the analysis of neutron diffraction data, suggests that the atomic magnetic moments in these compositions adopt a spin-glass-like state below T f . - Graphical abstract: The n=1 Ruddlesden-Popper system Pr 3-x Sr 1+x CrNiO 8 (0.0< x≤1.0) has been characterized by diffraction methods and magnetometry. There is no evidence of Cr/Ni cation ordering in any composition. The atomic magnetic moments adopt a spin-glass-like state below a transition temperature that decreases from 52 K (x=0.1) to 13 K (x=1.0)

  5. A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide.

    Science.gov (United States)

    Ng, Chee Koon; Wu, Jie; Hor, T S Andy; Luo, He-Kuan

    2016-09-27

    Binary catalyst systems comprising a cationic Ru-CNC pincer complex and an alkali metal salt were developed for selective hydroboration of CO 2 utilizing pinacolborane at r.t. and 1 atm CO 2 , with the combination of [Ru(CNC Bn )(CO) 2 (H)][PF 6 ] and KOCO 2 t Bu producing formoxyborane in 76% yield. A bicyclic catalytic mechanism was proposed and discussed.

  6. Reduction of , -Unsaturated Ketones Using a Zn/NiCl System in ...

    African Journals Online (AJOL)

    NJD

    Reduction of , -Unsaturated Ketones Using a Zn/NiCl. 2. System in Aqueous Media in the Presence of Anionic and. Cationic Surfactants. Hocine Ilikti*, Tayeb Benabdallah, Kamel Bentayeb, Adil A. Othman and Zoubir Derriche. Organic Chemistry and Electrochemistry Laboratory, Department of Chemistry, Faculty of Science, ...

  7. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation.

    Science.gov (United States)

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-28

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  8. Computer augumented modelling studies of Pb(II, Cd(II, Hg(II, Co(II, Ni(II, Cu(II and Zn(II complexes of L-glutamic acid in 1,2-propanediol–water mixtures

    Directory of Open Access Journals (Sweden)

    MAHESWARA RAO VEGI

    2008-12-01

    Full Text Available Chemical speciation of Pb(II, Cd(II, Hg(II, Co(II, Ni(II, Cu(II and Zn(II complexes of L-glutamic acid was studied at 303 K in 0–60 vol. % 1,2-propanediol–water mixtures, whereby the ionic strength was maintained at 0.16 mol dm-3. The active forms of the ligand are LH3+, LH2 and LH–. The predominant detected species were ML, ML2, MLH, ML2H and ML2H2. The trend of the variation in the stability constants with changing dielectric constant of the medium is explained based on the cation stabilizing nature of the co-solvents, specific solvent–water interactions, charge dispersion and specific interactions of the co-solvent with the solute. The effect of systematic errors in the concentrations of the substances on the stability constants is in the order alkali > > acid > ligand > metal. The bioavailability and transportation of metals are explained based on distribution diagrams and stability constants.

  9. Forging Colloidal Nanostructures via Cation Exchange Reactions.

    Science.gov (United States)

    De Trizio, Luca; Manna, Liberato

    2016-09-28

    Among the various postsynthesis treatments of colloidal nanocrystals that have been developed to date, transformations by cation exchange have recently emerged as an extremely versatile tool that has given access to a wide variety of materials and nanostructures. One notable example in this direction is represented by partial cation exchange, by which preformed nanocrystals can be either transformed to alloy nanocrystals or to various types of nanoheterostructures possessing core/shell, segmented, or striped architectures. In this review, we provide an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange. At the same time, the review gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions, as they are currently understood, and outlines the main open issues and possible future developments in the field.

  10. Forging Colloidal Nanostructures via Cation Exchange Reactions

    Science.gov (United States)

    2016-01-01

    Among the various postsynthesis treatments of colloidal nanocrystals that have been developed to date, transformations by cation exchange have recently emerged as an extremely versatile tool that has given access to a wide variety of materials and nanostructures. One notable example in this direction is represented by partial cation exchange, by which preformed nanocrystals can be either transformed to alloy nanocrystals or to various types of nanoheterostructures possessing core/shell, segmented, or striped architectures. In this review, we provide an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange. At the same time, the review gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions, as they are currently understood, and outlines the main open issues and possible future developments in the field. PMID:26891471

  11. Calix[6]arenes functionalized with malondiamides at the upper rim as possible extractants for lanthanide and actinide cations

    International Nuclear Information System (INIS)

    Almaraz, M.; Esperanza, S.; Magrans, O.; Mendoza, J. de; Pradus, P.

    2001-01-01

    Lipophilic malondiamides have been recently employed successfully as extractants for lanthanide and actinide cations from strongly acidic media. Many complexes between malondiamides and lanthanide-actinides cations have been studied by different techniques. For many of these complexes it has been observed that more than one malondiamide ligand participates in the complexation of each metallic cation. Incorporation of two or three malondiamide moieties into a calixarene platform would probably improve both extraction and selectivity with respect to the already tested malondiamides. According to CPK examination, a calix[6]arene substituted at the upper rim with two or three malondiamide moieties should constitute a promising ligand for lanthanide and actinide cations due to co-operative complexation with the malondiamides. Based on these considerations, we synthesised calix[6]arenes functionalized with malonic acid derivatives. (author)

  12. Gallium-Indium ordering in the complex [Ni{sub 2}Ga{sub 3}In] network of GdNi{sub 2}Ga{sub 3}In

    Energy Technology Data Exchange (ETDEWEB)

    Galadzhun, Yaroslav V.; Horiacha, Myroslava M.; Nychyporuk, Galyna P.; Zaremba, Vasyl I. [Inorganic Chemistry Department, Ivan Franko National University of Lviv (Ukraine); Rodewald, Ute C.; Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany)

    2016-08-15

    Polycrystalline samples of the isotypic quaternary compounds RENi{sub 2}Ga{sub 3}In (RE = Y, Gd - Tm) were obtained by arc-melting of the elements. Crystals of the gadolinium compound were found by slow cooling of an arc-melted button of the initial composition ''GdNiGa{sub 3}In''. All samples were characterized by powder X-ray diffraction. The structure of GdNi{sub 2}Ga{sub 2.89}In{sub 1.11} was refined from single-crystal X-ray diffractometer data: new type, Pnma, a = 2426.38(7), b = 418.17(2), c = 927.27(3) pm, wR{sub 2} = 0.0430, 1610 F{sup 2} values and 88 variables. Two of the six crystallographically independent gallium sites show a small degree of Ga/In mixing. The nickel atoms show tricapped trigonal prismatic coordination by gadolinium, gallium, and indium. Together, the nickel, gallium, and indium atoms build up a complex three-dimensional [Ni{sub 2}Ga{sub 3}In]{sup δ-} network, which leaves cages for the gadolinium atoms. The indium atoms form zigzag chains with In-In distances of 337 pm. The crystal chemical similarities of the polyhedral packing in the GdNi{sub 2}Ga{sub 3}In and La{sub 4}Pd{sub 10}In{sub 21} structures are discussed. (Copyright copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. A cationic Ag-I(PNPtBu) species acting as PNP transfer agent: Facile synthesis of Pd(PNPtBu)(alkyl) complexes and their reactivity compared to PCPtBu analogues

    NARCIS (Netherlands)

    van der Vlugt, J.I.; Siegler, M.A.; Janssen, M.; Vogt, D.; Spek, A.L.

    2009-01-01

    The straightforward Synthesis of cationic complex 1, [Ag(PNtBu)]BF4 (PNPtBu = 1,2-bis[(di-tert-butylphosphino)methyl]pyridine), and its facile transmetalating properties toward gold and palladium are described. The corresponding Au complex [Au(PNPtBu)](2)(BF4)(2) (2) exists its a dimer in the solid

  14. Di-?-cyanido-tetra?cyanido(5,5,7,12,12,14-hexa?methyl-1,4,8,11-tetra?aza?cyclo?tetra?decane)[N-(quinolin-8-yl)quinoline-2-carboxamidato]diiron(III)nickel(II) 2.07-hydrate

    OpenAIRE

    Yang, Yuqi; Zhou, Hongbo; Shen, Xiaoping

    2013-01-01

    The asymmetric unit of the title complex, [Fe2Ni(C19H12N3O)2(CN)6(C16H36N4)]?2.07H2O, contains one [Fe(qcq)(CN)3]? anion, half a [Ni(teta)]2+ cation and two partially occupied inter?stitial water mol?ecules [qcq? is the N-(quinolin-8-yl)quinoline-2-carboxamidate anion and teta is 5,5,7,12,12,14-hexa?methyl-1,4,8,11-tetra?aza?cyclo?tetra?deca?ne]. In the complex mol?ecule, two [Fe(qcq)(CN)3]? anions additionally coordinate the central [Ni(teta)]2+ cation through cyanide groups in a trans mode,...

  15. Magnetic studies on Layered solid solution Lix(Ni0.4Mn0.6)2-xO2

    International Nuclear Information System (INIS)

    Nakao, K; Nakamura, T; Yamada, Y; Koshiba, N

    2011-01-01

    Li x (Ni 0.4 Mn 0.6 ) 2-x O 2 (1.09≤x≤1.23) were prepared by the solid-state reaction using LiOH and coprecipitated mixed hydroxide as raw materials. All the compounds have a layered rock-salt structure, and the cation mixing degree (Ni 2+ occupancy in the Li-layer) decreases with an increase in x. From the low-temperature magnetic measurement, they all have negative Weiss temperature and spontaneous magnetization, that is, they are ferromagnetic materials. Both the Curie temperature and the spontaneous magnetization at 4.2K decrease with an increase in x. These magnetic variations are attributed to the lowering of the cation mixing degree: the magnetic interaction network turns to two-dimensional one with the loss of the inert-layer coupling. These situations may be considered semi-quantitatively using the ferromagnetic cluster model. Additionally, the cation mixing degree has an influence on their electrochemical properties such as cycle fading and rate capability.

  16. 99mTcO(BAT-NI), a novel nitroimidazole tracer: in vivo uptake studies in ischaemic myocardium

    International Nuclear Information System (INIS)

    Hoffend, J.; Linke, G.; Mohammed, A.; Haberkorn, U.; Tiefenbacher, C.P.; Eisenhut, M.

    2003-01-01

    Myocardial perfusion single-photon emission tomography (SPET) performed with cationic technetium-99m complexes indicates ischaemic areas as cold lesions. By contrast, nitroimidazole derivatives labelled with fluorine-18 or 99m Tc have recently shown promising results for hot spot imaging of ischaemic myocardium. This study evaluates 99m TcO(BAT-NI), a new 99m Tc complex comprising the nitroimidazole ligand, 2,10-dimercapto-2, 10-dimethyl-4, 8-diaza-6-[4-(2-nitroimidazolyl)butyl]undecane, in a low-flow in vivo model of myocardial ischaemia in thoracotomised rats. To elucidate the influence of the 2-nitroimidazole group on ischaemia-induced uptake, comparisons with ligand derivatives were performed where (a) the 2-nitro group was deleted [ 99m TcO(BAT-I)], (b) the 2-nitroimidazole functionality was replaced by a Br atom [ 99m TcO(BAT-Br)] and (c) the 99m TcO(BAT) moiety was replaced by an iodine-125 iodophenoxybutyl ligand ( 125 IP-NI). The radiolabelled compounds were i.v. injected 15 min after reducing resting myocardial blood flow by 50-60% and the uptake of radioactivity was assessed 90 min post injection. Autoradiography of left ventricular short-axis slices showed median uptake ratios of ischaemic/non-ischaemic myocardium (I/N) of 3.4, 4.5 and 3.4 for 99m TcO(BAT-NI), 99m TcO(BAT-I) and 99m TcO(BAT-Br), respectively. In contrast, 125 IP-NI was not preferentially taken up by ischaemic myocardium. Accumulation of 99m TcO(BAT-NI) in ischaemic heart regions was comparable to that in the liver. Biodistribution studies showed a median uptake of 0.65% ID/g of 99m TcO(BAT-NI) in ischaemic tissue and an I/N of 3.3. On planar images of the thorax and upper abdomen the ischaemic hearts were visualised faintly; the median heart to lung count ratio for 99m TcO(BAT-NI) was 1.7, and the median heart to liver count ratio was 1.0. We conclude that uptake of 99m TcO(BAT-NI) in ischaemic myocardium does not depend on the nitroimidazole moiety but is intrinsic to the BAT complex

  17. The Metal Cation Chelating Capacity of Astaxanthin. Does This Have Any Influence on Antiradical Activity?

    Directory of Open Access Journals (Sweden)

    Ana Martínez

    2012-01-01

    Full Text Available In this Density Functional Theory study, it became apparent that astaxanthin (ASTA may form metal ion complexes with metal cations such as Ca+2, Cu+2, Pb+2, Zn+2, Cd+2 and Hg+2. The presence of metal cations induces changes in the maximum absorption bands which are red shifted in all cases. Therefore, in the case of compounds where metal ions are interacting with ASTA, they are redder in color. Moreover, the antiradical capacity of some ASTA-metal cationic complexes was studied by assessing their vertical ionization energy and vertical electron affinity, reaching the conclusion that metal complexes are slightly better electron donors and better electron acceptors than ASTA.

  18. Infrared Spectroscopic and Theoretical Study of the HC_nO^+(N=5-12) Cations

    Science.gov (United States)

    Li, Wei; Jin, Jiaye; Wang, Guanjun; Zhou, Mingfei

    2017-06-01

    Carbon chains and derivatives are highly active species, which are widely existed as reactive intermediates in many chemical processes including atmospheric chemistry, hydrocarbon combustion, as well as interstellar chemistry. The carbon chain cations, HC_nO^+ (n = 5-12) are produced via pulsed laser vaporization of a graphite target in supersonic expansions containing carbon monoxide and hydrogen. The infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO "tagged" [HC_nO.CO] cation complexes in the 1600-3500 \\wn region. The geometries and electronic ground states of these cation complexes are determined by their infrared spectra in conjunction with theoretical calculations. All the HC_nO^+ (n = 5-12) core cations are characterized to be linear carbon chain derivatives terminated by hydrogen and oxygen. The HC_nO^+ cations with odd n have closed-shell singlet ground states with polyyne-like structures, while those with even n have triplet ground states with allene-like structures.

  19. Hydrothermal synthesis and study of an inorganic-organic hybrid vanadate of a nickel(II) coordination complex with pyrazine, Ni{sub 3}(C{sub 4}H{sub 4}N{sub 2}){sub 3}(V{sub 8}O{sub 23})

    Energy Technology Data Exchange (ETDEWEB)

    Larrea, Edurne S. [Dpto. de Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, UPV/EHU, Apdo. 644, E-48080 Bilbao (Spain); Mesa, Jose L., E-mail: joseluis.mesa@ehu.es [Dpto. de Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, UPV/EHU, Apdo. 644, E-48080 Bilbao (Spain); Arriortua, Maria I. [Dpto. de Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, UPV/EHU, Apdo. 644, E-48080 Bilbao (Spain)

    2011-06-15

    Highlights: {yields} A novel inorganic-organic hybrid vanadate of nickel(II) coordination complex with pyrazine has been synthesized hydrothermally. {yields} The thermal and spectroscopic behavior has been studied. {yields} The compound shows AFM interactions which has been fitted to a magnetic model of lineal chains. -- Abstract: The three-dimensional hybrid compound Ni{sub 3}(C{sub 4}H{sub 4}N{sub 2}){sub 3}(V{sub 8}O{sub 23}) has been synthesized by mild hydrothermal methods under autogenous pressure at 170 {sup o}C. The structure of the phase is stable until 380 {sup o}C. The removal of the pyrazine molecules from the structure induces its collapse. The IR spectrum shows the vibration modes of the pyrazine molecule and those of the [VO{sub 4}]{sup 3-} groups. A UV-visible spectrum shows the characteristic bands of the Ni(II) d{sup 8}-high-spin cation in a slightly distorted octahedral coordination. Magnetic measurements indicate the existence of antiferromagnetic interactions that can be fitted with a chain model to give g = 2.31, J/k = -5.3, and zJ'/k = -5.5.

  20. Effects of complexing compounds on sorption of metal ions to cement

    Energy Technology Data Exchange (ETDEWEB)

    Loevgren, Lars [Umeaa Univ. (Sweden). Inorganic chemistry

    2005-12-15

    This present report is a literature review addressing the effects of complexing ligands on the sorption of radionuclides to solid materials of importance for repositories of radioactive waste. Focus is put on laboratory studies of metal ion adsorption to cement in presence of chelating agents under strongly alkaline conditions. As background information, metal sorption to different mineral and cement phases in ligand free systems is described. Furthermore, surface complexation model (SCM) theories are introduced. According to surface complexation theories these interactions occur at specific binding sites at the particle/water interface. Adsorption of cationic metals is stronger at high pH, and the adsorption of anions occurs preferentially at low pH. The adsorption of ions to mineral surfaces is a result of both chemical bonding and electrostatic attraction between the ions and charged mineral surfaces. By combining uptake data with spectroscopic information the sorption can be explained on a molecular level by structurally sound surface complexation models. Most of the metal sorption studies reviewed are dealing with minerals exhibiting oxygen atoms at their surfaces, mainly oxides of Fe(II,III) and Al(III), and aluminosilicates. Investigations of radionuclides are focused on clay minerals, above all montmorillonite and illite. Which mechanism that is governing the metal ion adsorption to a given mineral is to a large extent depending on the metal adsorbed. For instance, sorption of Ni to montmorillonite can occur by formation of inner-sphere mononuclear surface complexes located at the edges of montmorillonite platelets and by formation of a Ni phyllosilicate phase parallel to montmorillonite layers. Also metal uptake to cement materials can occur by different mechanisms. Cationic metals can both be attached to cement (calcium silicate hydrate, CSH) and hardened cement paste (HCP) by formation of inner-sphere complexes at specific surface sites and by

  1. Competing Pathways for Nucleation of the Double Perovskite Structure in the Epitaxial Synthesis of La 2 MnNiO 6

    Energy Technology Data Exchange (ETDEWEB)

    Spurgeon, Steven R.; Du, Yingge; Droubay, Timothy; Devaraj, Arun; Sang, Xiahan; Longo, Paolo; Yan, Pengfei; Kotula, Paul G.; Shutthanandan, Vaithiyalingam; Bowden, Mark E.; LeBeau, James M.; Wang, Chongmin; Sushko, Peter V.; Chambers, Scott A.

    2016-06-14

    Over the past decades a confluence of advanced synthesis techniques, data-driven characterization, and rapid increases in computing power has sparked a renaissance in materials engineering. The emerging “materials-by-design” approach, while radically transforming the development of multicomponent systems, has tended to overlook the complex kinetic pathways that define materials synthesis. Although we are able to envision almost limitless materials combinations, we are unable to synthesize all of them in practice, since existing characterization and modeling approaches often fail to capture the inherent complexity of such systems. There is currently a disconnect between highly local structural characterization and macroscale properties measurements, resulting in oversimplified or incomplete structure-property models. Here we describe a multi-technique approach that combines aberration-corrected transmission electron microscopy with emerging oxide atom probe tomography to measure chemical ordering and extended defects in the model complex oxide, La2MnNiO6. We visualize cation ordering, as well as a three-dimensional network of secondary phases, which we describe in terms of ab initio structure calculations. We propose a defect model in which these phases alter their surrounding octahedral environment, severely disrupting cation superexchange. Through this array of experimental and theoretical techniques, we uncover fundamental structure-property relationships and illustrate a new approach to engineer complex, multicomponent systems.

  2. Density functional study of carbon monoxide adsorption on small cationic, neutral, and anionic aluminum nitride clusters

    Science.gov (United States)

    Guo, Ling

    CO adsorption on small cationic, neutral, and anionic (AlN)n (n = 1-6) clusters has been investigated using density functional theory in the generalized gradient approximation. Among various possible CO adsorption sites, an N on-top (onefold coordinated) site is found to be the most favorable one, irrespective of the charge state of the clusters. The adsorption energies of CO on the anionic (AlN)nCO (n = 2-4) clusters are greater than those on the neutral and cationic complexes. The adsorption energies on the cationic and neutral complexes reflect the odd-even oscillations, and the adsorption energies of CO on the cationic (AlN)nCO (n = 5, 6) clusters are greater than those on the neutral and anionic complexes. The adsorption energies for the different charge states decrease with increasing cluster size.

  3. Synthesis, spectral, thermal studies and electrical conductivity of Co (II) and Ni (II) complexes 3-[4-dimethylaminophenyl]-1-(2-pyridyl) prop-2-en-1-one (DMAPP)

    Energy Technology Data Exchange (ETDEWEB)

    Gaber, Mohamed, E-mail: abuelazm@yahoo.com [Chemistry Department, Faculty of Science, Tanta University, 31527 Tanta (Egypt); Al-Daly, Samy; Fayed, Tarek [Chemistry Department, Faculty of Science, Tanta University, 31527 Tanta (Egypt); El-Sayed, Yousif [Department of Chemistry, Faculty of Science, Tanta University, Tanta (Egypt)

    2015-01-15

    Co(II) and Ni(II) complexes of 3-[4-dimethylaminophenyl]-1-(2-pyridyl)prop-2-en-1-one have been prepared and characterized on the basis of elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra as well as thermal studies. The magnetic and spectral studies suggested the octahedral geometry for Co(II) and Ni(II) complexes. The kinetic parameters of the thermal decomposition stages have been evaluated using Coats–Redfern method. The electrical conductivity of the titled ligand and its Co(II) complexes was studied. The effects of different alcoholic solvents, pH and temperature on the complexation formation were considered. Also, the effect of Co(II) and Ni(II) ions on the emission spectrum of the free DMAPP was assigned. The stoichiometry of the metal complexes, the conditional formation constant, free energy, Beer{sup '}s law, molar extinction coefficient as well as specific absorptivity were evaluated. The ability of using the titled ligand as metalochromic indicator in complexometric titration was studied.

  4. An experimental and theoretical study on the interaction of DNA and BSA with novel Ni2 +, Cu2 + and VO2 + complexes derived from vanillin bidentate Schiff base ligand

    Science.gov (United States)

    Dostani, Morteza; Kianfar, Ali Hossein; Mahmood, Wan Ahmad Kamil; Dinari, Mohammad; Farrokhpour, Hossein; Sabzalian, Mohammad R.; Abyar, Fatemeh; Azarian, Mohammad Hossein

    2017-06-01

    In this investigation, the structure of bidentate N,N-Schiff base ligand of vanillin, (E)-4-(((2-amino-5-nitrophenyl)imino)methyl)-2-methoxyphenol (HL) was determined by single crystal X-ray diffraction. The interaction of new [CuL2], [NiL2] and [VOL2] complexes with DNA and BSA was explored through UV-Vis and fluorescence spectroscopy. The electronic spectra changes displayed an isosbestic point for the complexes upon titration with DNA. The Kb values for the complexes [CuL2], [NiL2] and [VOL2] were 2.4 × 105, 1.9 × 105 and 4.2 × 104, respectively. [CuL2] complex was bound more toughly than [NiL2] and [VOL2] complexes. These complexes had a significant interaction with Bovine Serum Albumin (BSA) and the results demonstrated that the quenching mechanism was a static procedure. Also, the complexes interacted with BSA by more than one binding site (n > 1). Finally, the theoretical studies were performed using the docking method to calculate the binding constants and recognize the binding site of the DNA and BSA with the complexes. The ligand and complexes including Ni2 +, Cu2 + and VO2 + ions were colonized by fungal growth.

  5. The complex nature of calcium cation interactions with phospholipid bilayers

    Czech Academy of Sciences Publication Activity Database

    Melcrová, Adéla; Pokorná, Šárka; Pullanchery, S.; Kohagen, Miriam; Jurkiewicz, Piotr; Hof, Martin; Jungwirth, Pavel; Cremer, P. S.; Cwiklik, Lukasz

    2016-01-01

    Roč. 6, DEC 2016 (2016), č. článku 38035. ISSN 2045-2322 R&D Projects: GA ČR(CZ) GBP208/12/G016; GA ČR(CZ) GA16-01074S Institutional support: RVO:61388955 ; RVO:61388963 Keywords : FLUORESCENCE SOLVENT RELAXATION * MOLECULAR-DYNAMICS SIMULATIONS * ALKALINE-EARTH CATION S Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.259, year: 2016

  6. A Novel Cyanide-Bridged Thulium-Nickel Heterobimetallic Polymeric Complex (H2O)2(DMF)10Tm2[Ni(CN)4]2[Ni(CN)4] including O-H···N Hydrogen Bond

    International Nuclear Information System (INIS)

    Chung, Janghoon; Park, Daeyoung; Song, Mina; Ha, Sungin; Kang, Ansoo; Moon, Sangbong; Ryu, Cheolhwi

    2012-01-01

    The experimental section lists the observed infrared absorption frequencies for the complex. Typically bridging CN ligands have higher stretching frequencies than the terminal CN ligands. Accordingly, cyanide stretching bands (2170, 2156, 2139 cm -1 . at higher frequencies than the stretching band (2127 cm -1 ) of K 2 [Ni(CN) 4 ] are assigned to bridging cyanide ligands. The band at 2128 cm -1 is assigned to terminal cyanide ligands because their location in the cyanide stretching region compares with the absorption observed for the nonbridging cyanide ligands in K 2 [Ni(CN) 4 ]. Array (H 2 O) 2 (DMF) 10 Tm 2 [Ni(CN) 4 ] 2 [Ni(CN) 4 ] and other lanthanide metal-Ni systems display similar CN stretching patterns in their spectra. A broad absorption band at 2950-3550 cm -1 was observed in the spectrum. This supports the presence of O-H···N intermolecular hydrogen bond interactions between the polymers

  7. Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

    Directory of Open Access Journals (Sweden)

    Awatef Ayadi

    2015-08-01

    Full Text Available The synthesis and full characterization of two tetrathiafulvalene-appended azine ligands, namely 2-([2,2’-bi(1,3-dithiolylidene]-4-yl-6-((2,4-dinitrophenylhydrazonomethylpyridine (L1 and 5-([2,2’-bi(1,3-dithiolylidene]-4-yl-2-((2,4-dinitrophenylhydrazonomethylpyridine (L2 are described. The crystal structure of ligand L1 indicates that the ligand is completely planar with the presence of a strong intramolecular N3–H3···O1 hydrogen bonding. Titration experiments with inorganic anions showed that both ligands are suitable candidates for the sensing of fluoride anions. Ligand L2 was reacted with a Re(I cation to yield the corresponding rhenium tricarbonyl complex 3. In the crystal structure of the newly prepared electroactive rhenium complex the TTF is neutral and the rhenium cation is hexacoordinated. The electrochemical behavior of the three compounds indicates that they are promising for the construction of crystalline radical cation salts.

  8. Structural and dielectric characteristics of double perovskite La2(NiFe)1/2MnO6

    Science.gov (United States)

    Nasir, Mohd.; Kandasami, Asokan; Sen, Somaditya

    2018-05-01

    Recently, La2NiMnO6 has drawn significant interest because large magnetic field induced changes in dielectric properties makes this compound a promising material for potential spintronic device applications. In the present study, the structural and dielectric characteristics of sol-gel prepared La2(Ni1/2Fe1/2)MnO6 double perovskite ceramics were evaluated. La2(Ni1/2Fe1/2)MnO6 was crystallized in the monoclinic P21/n structure with ordered Ni2+/Fe2+ and Mn4+ cations. A giant dielectric constant with relaxor-like behavior was observed, which was attributed to the dipolar effects arising from hopping between Ni2+/Fe2+ and Mn4+ ions.

  9. Evaluation of the complexes of galactomannan of Leucaena leucocephala and Co2+, Mn2+ , Ni2+ and Zn2+

    Directory of Open Access Journals (Sweden)

    Mercê Ana Lucia R.

    2000-01-01

    Full Text Available The binding constants for the complexed species formed in aqueous solution between galactomannan of Leucaena leucocephala and the metal ions Co2+, Mn2+, Ni2+ and Zn2+ were determined by potentiometric titrations. The calculated values showed Ni2+ as the best Lewis acid towards the Lewis base -OH groups of the sugar monomers, with Zn2+ being the poorest. For all systems, a higher percentage of the complexed species was present near pH=7.0, although complexed species existed over a wide range of acidic and basic pH values. The isolated solid complexes were studied by TG-DSC thermal analysis and by EPR spectroscopy. The thermal profiles obtained showed higher thermal resistance to final degradation than the biopolymer alone for the complexed species ML having the smallest log K values. The EPR spectra confirmed the complexation of the metal ions via the Lewis base deprotonated hydroxyl groups (-O and showed that the distances between metal ions in the complexed biopolymer structure depend on the nature of the metal ion. The ability of galactomannans to complex a variety of metal ions in their web like structure and the resistance to high temperatures and a wide range of pH values of these complexes open new perspectives in possible industrial uses whenever these properties are required, such as in bioremediation of waste waters and in the application of slow-release fertilizers.

  10. Characterization of Cu–Ni nanostructured alloys obtained by a chemical route. Influence of the complexing agent content in the starting solution

    Energy Technology Data Exchange (ETDEWEB)

    Carreras, Alejo C., E-mail: acarreras@famaf.unc.edu.ar [Instituto de Física Enrique Gaviola (IFEG), Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba—CONICET, Medina Allende s/n, Ciudad Universitaria, 5016 Córdoba (Argentina); Cangiano, María de los A.; Ojeda, Manuel W.; Ruiz, María del C. [Instituto de Investigaciones en Tecnología Qumica (INTEQUI), Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis—CONICET, Chacabuco y Pedernera, 5700 San Luis (Argentina)

    2015-03-15

    The influence of the amount of complexing agent added to the starting solution on the physicochemical properties of Cu–Ni nanostructured alloys obtained through a chemical route, was studied. For this purpose, three Cu–Ni nanoalloy samples were synthesized by a previously developed procedure, starting from solutions with citric acid to metal molar ratios (C/Me) of 0.73, 1.00 and 1.50. The synthesis technique consisted in preparing a precursor via the citrate-gel method, and carrying out subsequent thermal treatments in controlled atmospheres. Sample characterization was performed by scanning electron microscopy, X-ray microanalysis, X-ray diffraction, transmission electron microscopy, X-ray nanoanalysis and electron diffraction. In the three cases, copper and nickel formed a solid solution with a Cu/Ni atomic ratio close to 50/50, and free of impurities inside the crystal structure. The citric acid content of the starting solution proved to have an important influence on the morphology, size distribution, porosity, and crystallinity of the Cu–Ni alloy microparticles obtained, but a lesser influence on their chemical composition. The molar ratio C/Me = 1.00 resulted in the alloy with the Cu/Ni atomic ratio closest to 50/50. - Highlights: • We synthesize Cu–Ni nanoalloys by a chemical route based on the citrate-gel method. • We study the influence of the complexing agent content of the starting solution. • We characterize the samples by electron microscopy and X-ray techniques. • Citric acid influences the shape, size, porosity and crystallinity of the alloys.

  11. Aggregation of trypsin and trypsin inhibitor by Al cation.

    Science.gov (United States)

    Chanphai, P; Kreplak, L; Tajmir-Riahi, H A

    2017-04-01

    Al cation may trigger protein structural changes such as aggregation and fibrillation, causing neurodegenerative diseases. We report the effect of Al cation on the solution structures of trypsin (try) and trypsin inhibitor (tryi), using thermodynamic analysis, UV-Visible, Fourier transform infrared (FTIR) spectroscopic methods and atomic force microscopy (AFM). Thermodynamic parameters showed Al-protein bindings occur via H-bonding and van der Waals contacts for trypsin and trypsin inhibitor. AFM showed that Al cations are able to force trypsin into larger or more robust aggregates than trypsin inhibitor, with trypsin 5±1 SE (n=52) proteins per aggregate and for trypsin inhibitor 8.3±0.7 SE (n=118). Thioflavin T test showed no major protein fibrillation in the presence of Al cation. Al complexation induced more alterations of trypsin inhibitor conformation than trypsin. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. A spectroscopic and computational study of Al(III) complexes in cryolite melts: Effect of cation nature

    International Nuclear Information System (INIS)

    Nazmutdinov, Renat R.; Zinkicheva, Tamara T.; Vassiliev, Sergey Yu.; Glukhov, Dmitrii V.; Tsirlina, Galina A.; Probst, Michael

    2013-01-01

    Highlights: ► We investigate Li, Na and K cryolite melts by Raman spectroscopy and dft. ► A slight red shift of main Raman peaks is observed in the row Li + , Na + , K + . ► A decrease of the half-widths of peaks is observed in the same row. ► Fluoroaluminates and their complexation kinetics play an important role. - Abstract: Lithium, sodium and potassium cryolite melts are probed by Raman spectroscopy in a wide range of the melt composition. The experimental data demonstrate a slight red shift of main peaks and a decrease of their half-widths in the row Li + , Na + , K + . Quantum chemical modelling of the systems is performed at the density functional theory level. The ionic environment is found to play a crucial role in the energy of fluoroaluminates. Potential energy surfaces describing the formation/dissociation of certain complex species, as well as model Raman spectra are constructed and compared with those obtained recently for sodium containing cryolite melts (R.R. Nazmutdinov, et al., Spectrochim, Acta A 75 (2010) 1244.). The calculations show that the cation nature affects the geometry of the ionic associates as well as the equilibrium and kinetics of the complexation processes. This enables to interpret both original experimental data and those reported in literature

  13. Compositional and structural characterisation of Ni-phyllosilicates in hydrous silicate type Ni-laterite deposits

    OpenAIRE

    Villanova de Benavent, Cristina

    2015-01-01

    Ni-bearing Mg-phyllosilicates (commonly known as garnierites) are significant ore minerals in many Ni-laterite deposits worldwide. However, the characterisation of these mineral phases is complex, as well as their classification and nomenclature, due to their fine-grained nature, low crystallinity and frequent occurrence as mixtures. The aim of this study is to shed some light to the nature of the Ni-bearing Mg-phyllosilicates occurring at the Falcondo Ni-laterite. In this deposit, these ...

  14. Study of complex formation process between 4′-nitrobenzo-18-crown-6 and yttrium(III cation in some binary mixed non-aqueous solvents using the conductometry method

    Directory of Open Access Journals (Sweden)

    Mahboobeh Vafi

    2017-07-01

    Full Text Available The complexation reaction between Y3+ cation and macrocyclic ligand, 4′-nitrobenzo-18-crown-6 (4′NB18C6, was studied in acetonitrile–methanol (AN–MeOH, acetonitrile–1,2-dichloroethane (AN–DCE, acetonitrile–dimethylformamide (AN–DMF and acetonitrile–ethylacetate (AN–EtOAc binary mixed solvent solutions at different temperatures using the conductometric method. The conductance data show that in most cases, the stoichiometry of the complex formed between 4′NB18C6 and Y3+ cation is 1:1 [M:L], but in the case of AN-DCE binary solution (mol% DCE = 50 at 15, 25 and 35 °C, a 2:1 [M2:L] and also a 2:2 [M2:L2] complexes are formed in solution. The results show that the stoichiometry of the complex formed between 4′NB18C6 and Y3+ cation changes with the composition of the mixed solvents and even with temperature. The stability constant of the 1:1 complex was determined using a computer program, GENPLOT. The stability order of (4′NB18C6.Y3+ complex in pure studied solvents at 25 °C was found to be: EtOAc > AN > MeOH > DMF and in the case of the mixed solvent solutions with 25 mol percent of AN at 25 °C was: AN-DCE > AN-EtOAc > AN-MeOH ∼ AN-DMF. The values of stability constant (logKf of (4′NB18C6.Y3+ complex which were obtained from conductometric data, show that the stability of the complex is not only affected by the nature and composition of the solvent system, but it is also influenced by the temperature. In all cases, a non-linear behavior is observed for changes of logKf of the (4′NB18C6.Y3+ complex versus the composition of the binary mixed solvents. The values of standard thermodynamic quantities (ΔH°c and ΔS°c for the complexation process which were obtained from temperature dependence of the stability constant of (4′NB18C6.Y3+ complex, show that depending on the solvent system, in most cases, the complex is enthalpy and also entropy stabilized, but in some cases, it is stabilized or

  15. A new one-dimensional NiII coordination polymer with a two-dimensional supramolecular architecture

    Directory of Open Access Journals (Sweden)

    Kai-Long Zhong

    2017-02-01

    Full Text Available A new one-dimensional NiII coordination polymer of 1,3,5-tris(imidazol-1-ylmethylbenzene, namely catena-poly[[aqua(sulfato-κOhemi(μ-ethane-1,2-diol-κ2O:O′[μ3-1,3,5-tris(1H-imidazol-1-ylmethylbenzene-κ3N3,N3′,N3′′]nickel(II] ethane-1,2-diol monosolvate monohydrate], {[Ni(SO4(C18H18N6(C2H6O20.5(H2O]·C2H6O2·H2O}n, was synthesized and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. The NiII cation is coordinated by three N atoms of three different 1,3,5-tris(imidazol-1-ylmethylbenzene ligands, one O atom of an ethane-1,2-diol molecule, by a sulfate anion and a water molecule, forming a distorted octahedral NiN3O3 coordination geometry. The tripodal 1,3,5-tris(imidazol-1-ylmethylbenzene ligands link the NiII cations, generating metal–organic chains running along the [100] direction. Adjacent chains are further connected by O—H...O hydrogen bonds, resulting in a two-dimensional supermolecular architecture running parallel to the (001 plane. Another water molecule and a second ethane-1,2-diol molecule are non-coordinating and are linked to the coordinating sulfate ions via O—H...O hydrogen bonds.

  16. Structural evidence for the sorption of Ni(II) atoms on the edges of montmorillonite clay minerals: a polarized X-ray absorption fine structure study

    Science.gov (United States)

    Dähn, Rainer; Scheidegger, André M.; Manceau, Alain; Schlegel, Michel L.; Baeyens, Bart; Bradbury, Michael H.; Chateigner, Daniel

    The nature of surface complexes formed on Ni uptake onto montmorillonite (a dioctahedral smectite) has been investigated over an extended time period by polarized extended X-ray absorption fine structure (P-EXAFS) spectroscopy. Self-supporting films of Ni-sorbed montmorillonite were prepared by contacting Ni and montmorillonite at pH 7.2, high ionic strength (0.3 M NaClO 4), and low Ni concentration ([Ni] initial = 19.9 μM) for 14- and 360-d reaction time. The resulting Ni concentration on the clay varied from 4 to 7 μmol/g. Quantitative texture analysis indicates that the montmorillonite particles were well orientated with respect to the plane of the film. The full width at half maximum of the orientation distribution of the c* axes of individual clay platelets about the normal to the film plane was 44.3° (14-d reaction time) and 47.1° (360-d reaction time). These values were used to correct the coordination numbers determined by P-EXAFS for texture effects. Ni K-edge P-EXAFS spectra were recorded at angles between the incident beam and the film normal equal to 10, 35, 55, and 80°. Spectral analysis led to the identification of three nearest cationic subshells containing 2.0 ± 0.5 Al at 3.0 Å and 2.0 ± 0.5 Si at 3.12 Å and 4.0 ± 0.5 Si at 3.26 Å. These distances are characteristic of edge-sharing linkages between Al and Ni octahedra and of corner-sharing linkages between Ni octahedra and Si tetrahedra, as in clay structures. The angular dependence of the Ni-Al and Ni-Si contributions indicates that Ni-Al pairs are oriented parallel to the film plane, whereas Ni-Si pairs are not. The study reveals the formation of Ni inner-sphere mononuclear surface complexes located at the edges of montmorillonite platelets and thus that heavy metals binding to edge sites is a possible sorption mechanism for dioctahedral smectites. Data analysis further suggests that either the number of neighboring Al atoms slightly increases from 1.6 to 2 or that the structural order

  17. A sigmoidal model for biosorption of heavy metal cations from aqueous media.

    Science.gov (United States)

    Özen, Rümeysa; Sayar, Nihat Alpagu; Durmaz-Sam, Selcen; Sayar, Ahmet Alp

    2015-07-01

    A novel multi-input single output (MISO) black-box sigmoid model is developed to simulate the biosorption of heavy metal cations by the fission yeast from aqueous medium. Validation and verification of the model is done through statistical chi-squared hypothesis tests and the model is evaluated by uncertainty and sensitivity analyses. The simulated results are in agreement with the data of the studied system in which Schizosaccharomyces pombe biosorbs Ni(II) cations at various process conditions. Experimental data is obtained originally for this work using dead cells of an adapted variant of S. Pombe and represented by Freundlich isotherms. A process optimization scheme is proposed using the present model to build a novel application of a cost-merit objective function which would be useful to predict optimal operation conditions. Copyright © 2015. Published by Elsevier Inc.

  18. Study of conformational and acid-base properties of norbadione A and pulvinic derivatives: Consequences on their complexation properties of alkaline and alkaline earth cations

    International Nuclear Information System (INIS)

    Kuad, P.

    2006-01-01

    This work deals with the study of norbadione A, a pigment extracted from mushrooms and known to complex cesium cations. The study of the acid-base properties of norbadione A has allowed to determine the relative acidity of the seven protonable functions of the molecule and to reveal a reversible isomerization of the double exocyclic bond of the pulvinic moieties. The observed change of configuration is induced by a hydrogen bond of the H-O-H type and by electrostatic interactions. Moreover, the microscopic protonation mechanism of the norbadione A has been analyzed, considering three different study media where the acid-base properties of the norbadione A are compared. In the presence of 0.15 mol.l -1 of NaCl, it has been observed a remarkable cooperativity in the protonation of the enol groups. At last, the use of different analytical methods (NMR, potentiometry and calorimetry) has allowed to study the complexing properties of the norbadione A towards cesium and other alkaline and rare earth cations. (O.M.)

  19. Crystalline structure of the manganites solid solution RE(Me,MnO3, (RE=Gd,Er; Me=Ni,Co

    Directory of Open Access Journals (Sweden)

    Peña, O.

    2009-08-01

    Full Text Available The structural properties of the manganites solid solution RE(Me,MnO3, RE=Er,Gd, have been studied by X-ray diffraction and electric measurements. Powders were prepared by solid state reaction between the component oxides. Incorporation of Ni2+ or Co2+ on the lattice in the Mn sites leads to changes in the parameters and symmetry of the perovskite or hexagonal compounds GdMnO3 and ErMnO3 respectively. The phase transitions depend on the amount of substituted Jahn-Teller Mn3+ cations, and, therefore, of the cooperative Jahn-Teller interaction weakness. Solid solutions based on GdMnO3 perovskite compound change from O’-type to O-type orthorhombic perovskite symmetry when the Mn3+ cation amount decreases, because of the progressive substitution for Ni, Co. This transition occurs for lower amount of Ni2+ than for Co2+ cation. The Er-based solid solutions showed a different behaviour. For Ni2+ and Co2+ incorporation there are changes from hexagonal ErMnO3-type lattice to perovskite-type symmetry, for 20 at% and 30 at% respectively of substituting cations. The resultant perovskites crystallised directly in the O-type orthorhombic perovskite structure. The steric influence seems to play a secondary role, such as it can be deduced of the small variation of the Goldschmidt tolerance factor, t, for perovskite structure.

    Las propiedades estructurales de las soluciones sólidas RE(Me,MnO3, RE=Gd,Er, Me=Ni,Co, han sido estudiadas por difracción de rayos X, (DRX y medidas eléctricas. Las fases se sintetizaron por reacción en estado sólido entre los óxidos componentes. La incorporación de los cationes Ni2+ y Co2+,3+ en la red en lugar de Mn lleva a cambios en los parámetros de red y en la simetría de la perovskita, GdMnO3 o del compuesto hexagonal Er

  20. Bis[μ-1,3-bis(diphenylphosphanylpropane-κ2P:P′]digold(I tetrachloridonickelate(II diethyl ether monosolvate

    Directory of Open Access Journals (Sweden)

    Asako Igashira-Kamiyama

    2013-06-01

    Full Text Available The title compound, [Au2(C27H26P22][NiCl4]·C4H10O, consists of a digold(I complex cation, an [NiCl4]2− complex anion and a diethyl ether solvent molecule. Two 1,3-bis(diphenylphosphanylpropane (dppp ligands bridge two AuI atoms, forming a metallacycle in which each of the AuI atoms is coordinated in a slightly distorted linear environment by two P atoms. In the complex anion, the NiII atom is coordinated by four chloride ligands in a distorted tetrahedral geometry. The complex cation and the complex anion form a cation–anion pair through two Au...Cl contacts of 3.040 (1 and 3.021 (2 Å. One of the phenyl groups of the dppp ligand is disordered over two positions with equal occupancies.

  1. Cation-pi interaction of the univalent silver cation with meso-octamethylcalix[4]pyrrole: Experimental and theoretical study

    Czech Academy of Sciences Publication Activity Database

    Polášek, Miroslav; Kvíčala, J.; Makrlík, E.; Křížová, Věra; Vaňura, P.

    2017-01-01

    Roč. 1130, FEB 2017 (2017), s. 408-413 ISSN 0022-2860 Grant - others:GA MŠk(CZ) 20/2015; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388955 Keywords : silver cation * meso-octamethylcalix[4]pyrrole * complexation Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.753, year: 2016

  2. Separation for the determination of 59/63Ni in radioactive wastes

    International Nuclear Information System (INIS)

    Lee, Chang Heon; Choi, Kwang Soon; Jee, Kwang Young; Kim, Won Ho; Jung, Kie Chul

    2005-01-01

    A study on the separation of 99 Tc, 94 Nb, 55 Fe, 90 Sr and 59/63 Ni in various radioactive wastes discharged from nuclear power plants has been performed for a use in their quantification which is indispensable for the evaluation of the radionuclide inventory. Ni was recovered along with Ca, Mg, Al, Cr, Ti, Mn, Ce, Na, K. and Cu through the sequential separation procedure of Re (as a surrogate of 99 Tc), Nb, Fe and Sr by anion exchange and Sr-SPec extraction chromatography. In this research, chemical separation of Ni from the co-existing elements was investigated by cation exchange and Ni-Spec extraction chromatography. Precipitation behaviour of Ni and the co-existing elements with dimethylglyoxime(DMG) was investigated in ammonium citrate/ethanol-H 2 O and tartaric acid/acetone-H 2 O in order to purify separated Ni fractions and to prepare 59/63 Ni source for the radioactivity measurement using a gas proportional counter. Recovery of Ni separated through ion exchange chromatographic separation procedure was 93.1% with relative standard deviation of 0.9%. In addition, recovery of Ni with DMG in the tartaric acid/acetone-H 2 O was 85.6% with relative standard deviation of 1.9%

  3. Unsaturated b-ketoesters and their Ni(II, Cu(II and Zn(II complexes

    Directory of Open Access Journals (Sweden)

    MUHAMMED BASHEER UMMATHUR

    2009-03-01

    Full Text Available A new series of b-ketoesters in which the keto group is attached to the olefinic linkage were synthesized by the reaction of methyl acetoacetate and aromatic aldehydes under specified conditions. The existence of these compounds predominantly in the intramolecularly hydrogen bonded enol form was well demonstrated from their IR, 1H-NMR and mass spectral data. Details on the formation of their [ML2] complexes with Ni(II, Cu(II and Zn(II and the nature of the bonding are discussed on the basis of analytical and spectral data.

  4. New complexes of Co(II, Ni(II, Cu(II with Schiff base N,N’-bis-(3-methoxy-saliciliden-3,3’-dimethylbenzidine

    Directory of Open Access Journals (Sweden)

    Alan Ionela

    2013-01-01

    Full Text Available The new N,N’-bis-(3-methoxy-saliciliden-3,3’-dimetilbenzidine (H2L Schiff base and complexes with Co(II, Ni(II and Cu(II of type [M(HLCl(H2O] (M=Co(II, Cu(II [M2L(H2O4]X2 (M=Co(II, X=ClO4 and M=Cu(II, X=NO3 and [M2L(CH3COO2] (M=Co(II, Ni(II, Cu(II were synthesised. The ligand and complexes were characterized by elemental analysis, conductibility measurements, magnetic moments at room temperature, IR, NMR, UV-VIS-NIR, EPR spectra and thermogravimetric analysis. A molar ratio of 1:1 or 1:2 between ligand and metal was determined from the elemental analysis. Except for perchlorate complex that behave as electrolyte, the rest of complexes are non-electrolytes. The spectral data suggest a tetrahedral, pseudo-tetrahedral or square-planar stereochemistry respectively, data confirmed by magnetic behaviour of complexes. The antimicrobial tests indicate a fungicide effect both for ligand and complexes.

  5. Synthesis, activity, and structure--activity relationship studies of novel cationic lipids for DNA transfer.

    Science.gov (United States)

    Byk, G; Dubertret, C; Escriou, V; Frederic, M; Jaslin, G; Rangara, R; Pitard, B; Crouzet, J; Wils, P; Schwartz, B; Scherman, D

    1998-01-15

    We have designed and synthesized original cationic lipids for gene delivery. A synthetic method on solid support allowed easy access to unsymmetrically monofunctionalized polyamine building blocks of variable geometries. These polyamine building blocks were introduced into cationic lipids. To optimize the transfection efficiency in the novel series, we have carried out structure-activity relationship studies by introduction of variable-length lipids, of variable-length linkers between lipid and cationic moiety, and of substituted linkers. We introduce the concept of using the linkers within cationic lipids molecules as carriers of side groups harboring various functionalities (side chain entity), as assessed by the introduction of a library composed of cationic entities, additional lipid chains, targeting groups, and finally the molecular probes rhodamine and biotin for cellular traffic studies. The transfection activity of the products was assayed in vitro on Hela carcinoma, on NIH3T3, and on CV1 fibroblasts and in vivo on the Lewis Lung carcinoma model. Products from the series displayed high transfection activities. Results indicated that the introduction of a targeting side chain moiety into the cationic lipid is permitted. A primary physicochemical characterization of the DNA/lipid complexes was demonstrated with this leading compound. Selected products from the series are currently being developed for preclinical studies, and the labeled lipopolyamines can be used to study the intracellular traffic of DNA/cationic lipid complexes.

  6. Infrared spectroscopic and theoretical study of the HC2n+1O+ (n = 2-5) cations

    Science.gov (United States)

    Jin, Jiaye; Li, Wei; Liu, Yuhong; Wang, Guanjun; Zhou, Mingfei

    2017-06-01

    The carbon chain cations, HC2n+1O+ (n = 2-5), are produced via pulsed laser vaporization of a graphite target in supersonic expansions containing carbon monoxide and hydrogen. The infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO "tagged" [HC2n+1O.CO]+ cation complexes in the 1600-3500 cm-1 region. The geometries and electronic ground states of these cation complexes are determined by their infrared spectra compared to the predications of theoretical calculations. All of the HC2n+1O+ (n = 2-5) core cations are characterized to be linear carbon chain derivatives terminated by hydrogen and oxygen, which have the closed-shell singlet ground states with polyyne-like carbon chain structures.

  7. The interplay of microstructure and magnetism in La{sub 3}Ni{sub 2}SbO{sub 9}

    Energy Technology Data Exchange (ETDEWEB)

    Battle, Peter D., E-mail: peter.battle@chem.ox.ac.uk [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QR (United Kingdom); Avdeev, Maxim [Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234 (Australia); Hadermann, Joke [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium)

    2014-12-15

    La{sub 3}Ni{sub 2}SbO{sub 9} adopts a perovskite-related structure in which the six-coordinate cation sites are occupied alternately by Ni{sup 2+} and a disordered arrangement of Ni{sup 2+}/Sb{sup 5+}. A polycrystalline sample has been studied by neutron diffraction in applied magnetic fields of 0≤H/kOe≤50 at 5 K. In 0 kOe, weak magnetic Bragg scattering consistent with the adoption of a G-type ferrimagnetic structure is observed; the ordered component of the magnetic moment was found to be 0.89(7) µ{sub B} per Ni{sup 2+} cation. This increased to 1.60(3) µ{sub B} in a field of 50 kOe. Transmission electron microscopy revealed variations in the Ni:Sb ratio across crystallites of the sample. It is proposed that these composition variations disrupt the magnetic superexchange interactions within the compound, leading to domain formation and a reduced average moment. The application of a magnetic field aligns the magnetisation vectors across the crystal and the average moment measured by neutron diffraction increases accordingly. The role played by variations in the local chemical composition in determining the magnetic properties invites comparison with the behaviour of relaxor ferroelectrics. - Graphical abstract: Composition variations across a crystal of La3Ni2SbO9 result in anomalous magnetic behavior. - Highlights: • Ordered magnetic moment of Ni{sup 2+} increases in an applied magnetic field. • Composition variations detected by electron microscopy. • Increase in magnetic moment can be explained by presence of composition variations.

  8. Ni(II, Pd(II and Pt(II complexes with ligand containing thiosemicarbazone and semicarbazone moiety: synthesis, characterization and biological investigation

    Directory of Open Access Journals (Sweden)

    SULEKH CHANDRA

    2008-07-01

    Full Text Available The synthesis of nickel(II, palladium(II and platinum(II complexes with thiosemicarbazone and semicarbazone of p-tolualdehyde are reported. All the new compounds were characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, 1H-NMR, IR and electronic spectral studies. Based on the molar conductance measurements in DMSO, the complexes may be formulated as [Ni(L2Cl2] and [M(L2]Cl2 (where M = Pd(II and Pt(II due to their non-electrolytic and 1:2 electrolytic nature, respectively. The spectral data are consistent with an octahedral geometry around Ni(II and a square planar geometry for Pd(II and Pt(II, in which the ligands act as bidentate chelating agents, coordinated through the nitrogen and sulphur/oxygen atoms. The ligands and their metal complexes were screened in vitro against fungal species Alternaria alternata, Aspergillus niger and Fusarium odum, using the food poison technique.

  9. Beta-Phosphinoethylboranes as Ambiphilic Ligands in Nickel-Methyl Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Fischbach, Andreas; Bazinet, Patrick R.; Waterman, Rory; Tilley, T. Don

    2007-10-28

    The ambiphilic {beta}-phosphinoethylboranes Ph{sub 2}PCH{sub 2}CH{sub 2}BR{sub 2} (BR{sub 2} = BCy{sub 2} (1a), BBN (1b)), which feature a ethano spacer CH{sub 2}CH{sub 2} between the Lewis acidic boryl and Lewis basic phosphino groups, were synthesized in nearly quantitative yields via the hydroboration of vinyldiphenylphosphine. Compounds 1a and 1b were fully characterized by elemental analysis, and by NMR and IR spectroscopy. X-ray crystallographic studies of compound 1b revealed infinite helical chains of the molecules connected through P{hor_ellipsis}B donor-acceptor interactions. The ability of these ambiphilic ligands to concurrently act as donors and acceptors was highlighted by their reactions with (dmpe)NiMe{sub 2}. Zwitterionic complexes (dmpe)NiMe(Ph{sub 2}PCH{sub 2}CH{sub 2}BCy{sub 2}Me) (2a) and (dmpe)NiMe(Ph{sub 2}PCH{sub 2}CH{sub 2}[BBN]Me) (2b) were generated via the abstraction of one of the methyl groups, forming a borate, and intramolecular coordination of the phosphine moiety to the resulting cationic metal center. Compound 2b was characterized by X-ray crystallography. Furthermore, B(C{sub 6}F{sub 5}){sub 3} abstracts the methyl group of a coordinated borate ligand to generate a free, 3-coordinate borane center in [(dmpe)NiMe(1a)]{sup +}[MeB(C{sub 6}F{sub 5}){sub 3}]{sup -} (3).

  10. Exploring backbone-cation alkyl spacers for multi-cation side chain anion exchange membranes

    Science.gov (United States)

    Zhu, Liang; Yu, Xuedi; Hickner, Michael A.

    2018-01-01

    In order to systematically study how the arrangement of cations on the side chain and length of alkyl spacers between cations impact the performance of multi-cation AEMs for alkaline fuel cells, a series of polyphenylene oxide (PPO)-based AEMs with different cationic side chains were synthesized. This work resulted in samples with two or three cations in a side chain pendant to the PPO backbone. More importantly, the length of the spacer between cations varied from 3 methylene (-CH2-) (C3) groups to 8 methylene (C8) groups. The highest conductivity, up to 99 mS/cm in liquid water at room temperature, was observed for the triple-cation side chain AEM with pentyl (C5) or hexyl (C6) spacers. The multi-cation AEMs were found to have decreased water uptake and ionic conductivity when the spacer chains between cations were lengthened from pentyl (C5) or hexyl (C6) to octyl (C8) linking groups. The triple-cation membranes with pentyl (C5) or hexyl (C6) groups between cations showed greatest stability after immersion in 1 M NaOH at 80 °C for 500 h.

  11. Kinetics and mechanisms of the reactions of alkyl radicals with oxygen and with complexes of Co(III), Ru(III), and Ni(III)

    International Nuclear Information System (INIS)

    Kelley, D.

    1990-01-01

    The kinetics of the reactions of C 2 H 5 radical with Co(NH 3 ) 5 X 2+ , Ru(NH 3 ) 5 X 2+ , and Co(dmgH) 2 (X) (Y) (X = Br, Cl, N 3 , SCN; Y = H 2 O, CH 3 CN) complexes were studied using laser flash photolysis of ethylcobalt complexes. The kinetics were obtained by the kinetic probe method. Some relative rate constants were also determined by a competition method based on ethyl halide product ratios. The kinetics of colligation reactions of a series of alkyl radicals with β-Ni(cyclam) 2+ were studied using flaser flash photolysis of alkylcobalt complexes. Again, the kinetics were obtained by employing the kinetic probe competition method. The kinetics of the unimolecular homolysis of a series of RNi(cyclam)H 2 O 2+ were studied. Activation parameters were obtained for the unimolecular homolysis of C 2 H 5 Ni(cyclam)H 2 O 2+ . Kinetic and thermodynamic data obtained from these reactions were compared with those for the σ-bonded organometallic complexes. The kinetics of the unimolecular homolysis of a series of RNi(cyclam)H 2 O 2+ complexes were studied by monitoring the formation of the oxygen insertion product RO 2 Ni(cyclam)H 2 O 2+ . The higher rate constants for the reactions of alkyl radicals with oxygen in solution, as compared with those measured in the gas phase, were discussed. 30 refs

  12. Assignment of solid-state 13C and 1H NMR spectra of paramagnetic Ni(II) acetylacetonate complexes aided by first-principles computations

    DEFF Research Database (Denmark)

    Rouf, Syed Awais; Jakobsen, Vibe Boel; Mareš, Jiří

    2017-01-01

    Recent advances in computational methodology allowed for first-principles calculations of the nuclear shielding tensor for a series of paramagnetic nickel(II) acetylacetonate complexes, [Ni(acac)2L2] with L = H2O, D2O, NH3, ND3, and PMe2Ph have provided detailed insight into the origin of the par......Recent advances in computational methodology allowed for first-principles calculations of the nuclear shielding tensor for a series of paramagnetic nickel(II) acetylacetonate complexes, [Ni(acac)2L2] with L = H2O, D2O, NH3, ND3, and PMe2Ph have provided detailed insight into the origin...

  13. meso-Octamethylcalix[4]pyrrole as an effective macrocyclic receptor for the univalent thallium cation in the gas phase: Experimental and theoretical study

    Science.gov (United States)

    Polášek, Miroslav; Makrlík, Emanuel; Kvíčala, Jaroslav; Křížová, Věra; Vaňura, Petr

    2018-02-01

    By using electrospray ionization mass spectrometry (ESI-MS), it was proven experimentally that the univalent thallium cation (Tl+) forms with meso-octamethylcalix[4]pyrrole (1) the cationic complex species 1 Tl+. When this kinetically stable cationcomplex 1 Tl+ is collisionally activated, it decomposes by elimination of the whole ligand 1 or small meso-octamethylcalix[4]pyrrole fragments. Further, applying quantum chemical DFT calculations, four different conformations of the resulting complex 1 Tl+ were derived. It means that under the present experimental conditions, this ligand 1 can be considered as a very effective macrocyclic receptor for the thallium cation.

  14. [N,N-Bis(2-aminoethylethane-1,2-diamine](ethane-1,2-diaminenickel(II thiosulfate trihydrate

    Directory of Open Access Journals (Sweden)

    Beatrix Seidlhofer

    2012-02-01

    Full Text Available The title compound, [Ni(C2H8N2(C6H18N4]S2O3·3H2O, was accidentally synthesized under solvothermal conditions applying [Ni(en3]Cl2 (en is ethane-1,2-diamine as the Ni source. The asymmetric unit consists of one discrete [Ni(tren(en]2+ complex [tren is N,N-bis(2-aminoethylethane-1,2-diamine] in which the Ni2+ cation is sixfold coordinated within a slightly distorted octahedron, one thiosulfate anion and three water molecules. In the crystal, the complex cations, anions and water molecules are linked by an intricate hydrogen-bonding network. One C atom of the tren ligand, as well as one O atom of a water molecule, are disordered over two sites and were refined using a split model (occupancy ratios = 0.85:15 and 0.60:0.40, respectively.

  15. Csbnd H⋯Ni and Csbnd H⋯π(chelate) interactions in nickel(II) complexes involving functionalized dithiocarbamates and triphenylphosphine

    Science.gov (United States)

    Sathiyaraj, E.; Thirumaran, S.; Selvanayagam, S.; Sridhar, B.; Ciattini, Samuele

    2018-05-01

    New bis(N-benzyl-N-substituted benzyldithiocarbamato-S,S‧)nickel(II) (1-3) and (N-benzyl-N-substituted benzyldithiocarbamato-S,S‧)(isothiocyanato-N)- (triphenylphosphane)nickel(II) (4-6) [where substituted benzyl = 2-HOsbnd C6H4sbnd CH2sbnd (1,4), 3-HOsbnd C6H4sbnd CH2sbnd (2,5), 4-Fsbnd C6H4sbnd CH2sbnd (3,6)] were synthesized and characterized using IR, electronic, and NMR (1H and 13C) spectra. X-ray structural analysis of homoleptic complex (1) and heteroleptic complexes (5 and 6) confirmed the presence of four coordinated nickel in a distorted square planar arrangement with NiS4 and NiS2PN chromophores, respectively. The νC-S stretching vibrations are observed around 990 cm-1 without any splitting supporting the bidentate coordination of the dithiocarbamate ligand. Electronic spectral studies of all the complexes (1-6) indicate that the geometry of the nickel atom is probably square planar. NMR spectra of all homoleptic and heteroleptic complexes (1-6) reveal a weak signal associated with the backbone carbon (N13CS2) in the region 204.0-210.0 ppm with a weak intensity characteristic of the quaternary carbon signals. The greater trans influence of triphenylphosphine in complexes 5 and 6 is supported by the long Nisbnd S distance compared to other Nisbnd S distance which is opposite to the NCS- ligand. In the structure of complex 5, C-H⋯π(chelate) interactions results in polymeric chain. Both structures show intramolecular Ni⋯H interactions but that on 6 is the strongest. C-H⋯π interactions are also found in 1, 5 and 6. Hirshfeld surface analysis and the associated 2D fingerprint plots of 1, 5 and 6 have been studied to evaluate intermolecular interactions. The molecular geometries of complexes 1, 5 and 6 have been optimized by abinitio HF method using LANL2DZ program.

  16. Coordination-organometallic hybrid materials based on the trinuclear M(II)-Ru(II) (M=Ni and Zn) complexes: Synthesis, structural characterization, luminescence and electrochemical properties

    Science.gov (United States)

    Pawal, S. B.; Lolage, S. R.; Chavan, S. S.

    2018-02-01

    A new series of trinuclear complexes of the type Ni[R-C6H4Ndbnd CH(O)C6H3Ctbnd CRu(dppe)2Cl]2 (1a-c) and Zn[Rsbnd C6H4Ndbnd CH(O)C6H3Ctbnd CRu(dppe)2Cl]2 (2a-c) have been prepared from the reaction of trans-[RuCl(dppe)2Ctbnd Csbnd C6H3(OH)(CHO)] (1) with aniline, 4-nitroaniline and 4-methoxyaniline (R1-3) in presence of nickel acetate and zinc acetate in CH2Cl2/MeOH (1:1) mixture. The structural properties of the complexes have been characterized by elemental analyses and spectroscopic techniques viz. FTIR, UV-Visible, 1H NMR and 31P NMR spectral studies. The crystal structure and morphology of the hybrid complexes was investigated with the help of X-ray powder diffraction (XRPD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The thermal properties of 1a-c and 2a-c were studied by thermogravimetric (TG) analysis. The electrochemical behaviour of the complexes reveals that all complexes displayed a quasireversible redox behaviour corresponding to Ru(II)/Ru(III) and Ni(II)/Ni(III) couples for 1a-c and only Ru(II)/Ru(III) couple for 2a-c. All complexes are emissive in solution at room temperature revealing the influence of substituents and solvent polarity on emission properties of the complexes.

  17. Characterization of tetraaza-AC8, a surfactant with cation complexing potential

    International Nuclear Information System (INIS)

    Arleth, Lise

    1995-01-01

    Being a surfactant with cation complexing potential, the Tetraaza-AC8 can, in the long term, possibly be applied for the selection and extraction of specific cations. This can be of interest for the handling of radioactive waste or in the chemical industries for extraction of rare earth molecules as for example Rhodium. A thorough characterization of the behavior and abilities of Tetraaza-AC8 is necessary before one can even think of taking it into a larger production with sight of a specific application. This project deals with the characterization of the behavior and abilities of Tetraaza- AC8. In order to make use of the surface active properties of Tetraaza-AC8 it is necessary to dissolve it in some kind of solvent. As water is an important solvent which is, in addition, both inexpensive and non-polluting it is the natural choice. The aim of the project can then precised as follows: To study the micelle formation of dilute aqueous solutions of Tetraaza- AC8 and to determine how the micelle formation is influenced by the addition of respectively CsF, CuF_2 and RhCl_3 to the solutions The primary method of analysis is small-angle scattering. As small-angle x-ray scattering (SAXS) and small-angle neutron scattering (SANS) emphasizes different parts of the micellar structure, the combination of the methods allows a good determination of the micellar shape. In order to support the interpretation of scattering data, density measurements, surface tension measurements and UV/visible light spectroscopy are also performed. The scattering data have been analyzed according to two fundamentally different methods of analysis namely the method of indirect Fourier transform and the method of fitting molecular based models of the micelles to the scattering spectra. The first chapter contains a short introduction to the field of surfactants and complexing macrocycles. The chemical structure of Tetraaza-AC8 will be explained and motivated. A short description of the synthesis

  18. Sorption by cation exchange

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1994-04-01

    A procedure for introducing exchange into geochemical/surface complexation codes is described. Beginning with selectivity coefficients, K c , defined in terms of equivalent fractional ion occupancies, a general expression for the molar based exchange code input parameters, K ex , is derived. In natural systems the uptake of nuclides onto complex sorbents often occurs by more than one mechanism. The incorporation of cation exchange and surface complexation into a geochemical code therefore enables sorption by both mechanisms to be calculated simultaneously. The code and model concepts are tested against sets of experimental data from widely different sorption studies. A proposal is made to set up a data base of selectivity coefficients. Such a data base would form part of a more general one consisting of sorption mechanism specific parameters to be used in conjunction with geochemical/sorption codes to model and predict sorption. (author) 6 figs., 6 tabs., 26 refs

  19. Structure-activity relationship of carbamate-linked cationic lipids bearing hydroxyethyl headgroup for gene delivery.

    Science.gov (United States)

    Zhi, Defu; Zhang, Shubiao; Qureshi, Farooq; Zhao, Yinan; Cui, Shaohui; Wang, Bing; Chen, Huiying; Yang, Baoling; Zhao, Defeng

    2013-12-01

    A novel series of carbamate-linked cationic lipids containing hydroxyl headgroup were synthesized and included in formulations for transfection assays. The DNA-lipid complexes were characterized for their ability to bind DNA, their size, ζ-potential and cytotoxicity. Compared with our previously reported cationic transfection lipid DDCDMA lacking the hydroxyl group and the commercially available, these cationic liposomes exhibited relatively higher transfection efficiency. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Sorption and thermodynamic of cation-basic center interactions of inorganic-organic hybrids synthesized from RUB-18

    Energy Technology Data Exchange (ETDEWEB)

    Macedo, T.R. [Institute of Chemistry, University of Campinas, UNICAMP, P.O. Box 6154, 13084-971 Campinas, Sao Paulo (Brazil); Petrucelli, G.C. [Institute of Chemistry, Federal University of Goias, UFG, P.O. Box 03, 75805-190 Jatai, Goias (Brazil); Airoldi, C., E-mail: airoldi@iqm.unicamp.br [Institute of Chemistry, University of Campinas, UNICAMP, P.O. Box 6154, 13084-971 Campinas, Sao Paulo (Brazil)

    2010-04-20

    Synthesized nanostructured hybrids from RUB-18 layered silicate, containing one (N) or three (3N) basic nitrogen atoms attached to pendant chains were applied for copper, nickel and cobalt sorptions. The isotherms obtained from batchwise processes were adjusted to the Freundlich and the Langmuir-Freundlich models for heterogeneous systems. The basic nitrogen centers/acidic cation interactions were followed by calorimetry under batchwise conditions and the results were analyzed by a modified Langmuir equation. The exothermic enthalpic values of -2.50 {+-} 0.30, -1.62 {+-} 0.10 and -1.35 {+-} 0.20 and -15.61 {+-} 0.20, -8.05 {+-} 0.14 and -20.48 {+-} 0.15 kJ mol{sup -1}, obtained for Cu{sup 2+}, Ni{sup 2+} and Co{sup 2+} titrations with C-RUB-xN (x = 1, 3) materials, suggest a favorable process at the solid/liquid interface for inorganic/organic hybrid cation sorptions. These thermodynamic data, expressed also by reaction spontaneity, infer the use of such hybrids for cation removal from aqueous solution.

  1. Bis(tripyrazol-1-ylmethanenickel(II tetracyanidonickelate(II dihydrate

    Directory of Open Access Journals (Sweden)

    Sean Parkin

    2009-12-01

    Full Text Available The title complex, [Ni(C10H10N62][Ni(CN4]·2H2O, contains an octahedral nickel(II cation and a square-planar nickel(II anion. Both the cation and the anion reside on a crystallographic center of inversion. The NiII center in the cation is coordinated by six pyrazol-1-yl rings of two chelating tripyrazol-1-ylmethane [HC(pz3] ligands, with Ni—N distances that range between 2.0647 (19 and 2.0828 (19 Å. The NiII center in the anion is coordinated by four cyanide ligands, with Ni—C distances in the range 1.869 (2–1.869 (3 Å. The [Ni(CN4]2− anions are linked by inversion-related water molecules into extended chains that run parallel to the a axis.

  2. Interaction of the univalent silver cation with [Gly6]-antamanide: Experimental and theoretical study

    Science.gov (United States)

    Makrlík, Emanuel; Böhm, Stanislav; Kvíčala, Jaroslav; Vaňura, Petr; Ruzza, Paolo

    2018-03-01

    On the basis of extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Ag+(aq) + 1.Na+(nb) ⇄ 1.Ag+ (nb) + Na+(aq) occurring in the two-phase water - nitrobenzene system (1 = [Gly6]-antamanide; aq = aqueous phase, nb = nitrobenzene phase) was determined as log Kex (Ag+,1·Na+) = 1.5 ± 0.1. Further, the stability constant of the 1·Ag+ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log βnb (1·Ag+) = 4.5 ± 0.2. Finally, by using quantum chemical DFT calculations, the most probable structure of the cationic complex species 1·Ag+ was derived. In the resulting complex, the "central" cation Ag+ is coordinated by four noncovalent interactions to the corresponding four carbonyl oxygen atoms of the parent ligand 1. Besides, the whole 1·Ag+ complex structure is stabilized by two intramolecular hydrogen bonds. The interaction energy of the considered 1·Ag+ complex was found to be -465.5 kJ/mol, confirming also the formation of this cationic species.

  3. 4-(2-Tetrathiafulvalenyl-ethenyl)pyridine (TTF-CH=CH-Py) radical cation salts containing poly(beta-diketonate) rare earth complexes: synthesis, crystal structure, photoluminescent and magnetic properties.

    Science.gov (United States)

    Pointillart, Fabrice; Maury, Olivier; Le Gal, Yann; Golhen, Stéphane; Cador, Olivier; Ouahab, Lahcène

    2009-08-03

    The reactions between the redox-active 4-(2-tetrathiafulvalenyl-ethenyl)pyridine ligand (TTF-CH=CH-Py) and the tris(1,1,1,5,5,5-hexafluoroacetylacetonate)Ln(III) (Ln = La and Nd) lead to the formation of compounds with the formulas {[La(hfac)(5)][(TTF-CH=CH-Py(*+))](2)} (1), {[Nd(hfac)(4)(H(2)O)][(TTF-CH=CH-Py(*+))]}(2) (2), and {[Nd(hfac)(4)(H(2)O)][(TTF-CH=CH-Py(*+))]}(2)(H(2)O)(C(6)H(14))(0.5) (3) (hfac(-) = 1,1,1,5,5,5-hexafluoroacetylacetonate anion). These compounds have been characterized by single-crystal X-ray diffraction, optical, and magnetic measurements. Compounds 1, 2, and 3 crystallize in the monoclinic C2/c, triclinic P1, and monoclinic P2(1)/c space groups, respectively. La(III) adopts a tetradecahedral geometry, while Nd(III) stands in a distorted capped square antiprism one. In 1, the inorganic network is formed by the [La(hfac)(5)](2-) dianionic complexes, while it is formed by a pseudo-dimeric dianionic unit of formula {[Nd(hfac)(4)(H(2)O)](2)}(2-) in 2 and 3. In all crystal structures, the organic network is constituted by the TTF-CH=CH-Py(*+) radical cations. The inorganic and organic networks interact through intermolecular contacts between the pyridine moieties of the TTF-CH=CH-Py(*+) radical cations and the Ln(III) ions. The luminescence properties of the Nd(III) ions (9400 cm(-1)) and fluorescence band of the TTF-CH=CH-Py(*+) radical cations (10200 cm(-1)) have been observed and studied for compound 2. Complexes 2 and 3 are paramagnetic because of Nd(III) ions. Compound 2 is a paramagnetic luminescent TTF-radical-cation-based material. Resistivity measurements have also been performed on these materials.

  4. Synthesis of bis(oxamato) transition metal complexes and Ni nanoparticles and their structural, magnetic, optical, and magneto-optical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Braeuer, Bjoern

    2008-07-02

    In the framework of this thesis mono- and oligonuclear Cu(II)- anf Ni(II)-bis(oxamato) complexes are synthesized in view on their magneto-optical properties and structurally characterized. About transition-charge and transition-metal induced deviations from the general reaction behaviour described in literature is reported. From electron-spin-resonance studies the spin-density distribution in the mononuclear Cu(II) complexes is derived. The influence on this by coordination geometry as well as the effects of the superexchange interaction are discussed and compared with results from the density functional theory (DFT). Trinuclear bis(oxamato) complexes are for the first time deposited on Si(111) substrates by spin coating and studied by means of the spectroscopic ellipsometry as well as the Raman spectroscopy and evaluated by means of DFT calculations. Magneto-optical Kerr-effect studies were performed on thin layers of these complexes as well as phthalocyanines. For the comparison the magnetic and magneto-optical properties of Ni nanoparticles in different organic matrices were studied. By means of the photoelectron spectroscopy the oxidation behaviour of these is studied and conclusions on charge-transfer processes between the matrices and the nanoparticles are drawn. [German] Im Rahmen dieser Arbeit werden ein- und mehrkernige Cu(II)- und Ni(II)-bis-(oxamato)-Komplexe im Hinblick auf ihre magneto-optischen Eigenschaften gezielt hergestellt und strukturell charakterisiert. Ueber ladungs- und uebergangsmetallinduzierte Abweichungen vom allgemeinen in der Literatur beschriebenen Reaktionsverhalten wird berichtet. Aus Elektronenspinresonanz-Untersuchungen wird die Spindichteverteilung in den einkernigen Cu(II)-Komplexen abgeleitet. Die Beeinflussung dieser durch die Koordinationsgeometrie sowie die Auswirkungen auf die Superaustausch- Wechselwirkung werden diskutiert und mit Ergebnissen der Dichtefunktionaltheorie (DFT) verglichen. Dreikernige bis

  5. Influence of Ni(II) and Fe(III) complexes of 1,2 dihydroxy 9,10 anthraquinone on the modification in calf thymus DNA upon gamma irradiation

    International Nuclear Information System (INIS)

    Das, Saurabh; Mandal, Parikshit C.

    2009-01-01

    Ionizing radiation when allowed to fall upon cells or DNA, the radicals produced modify the base-pair region of the double strands. Radiation-induced double-strand modifications in calf thymus DNA were detected using Ni(II) and Fe(III) complexes of 1,2 dihydroxy 9,10 anthraquinone (DHA). 60 Co was used as the source for γ-radiation and ethidium bromide (EB) as the fluorescent dye for detecting double-strand modifications caused in DNA. Results show that the Fe(III)-DHA complex is more efficient in modifying the base-pair region in double-stranded DNA in comparison to DHA or the Ni(II)-DHA complex

  6. A new Ni(II complex as a novel and efficient recyclable catalyst for the synthesis of pyrano[2,3-d]pyrimidines

    Directory of Open Access Journals (Sweden)

    M. Habibi Kheirabadi

    2016-12-01

    Full Text Available A simple and highly efficient one-pot three-component synthesis of a series of pyrido[2,3-d]pyrimidines from the condensation of barbituric acid, malononitrile and aromatic aldehydes using catalytic amount of a new Ni(II complex based on 5-nitro-N1-((pyridin-2-ylmethylene benzene-1,2-diamine (NiL is reported. This new heterogeneous catalyst has the advantages of being environmentally friendly, simple work-up and high yields character.

  7. Linking trace element variations with macronutrients and major cations in marine mussels Mytilus edulis and Perna viridis.

    Science.gov (United States)

    Liu, Fengjie; Wang, Wen-Xiong

    2015-09-01

    Marine mussels have long been used as biomonitors of contamination of trace elements, but little is known about whether variation in tissue trace elements is significantly associated with those of macronutrients and major cations. The authors examined the variability of macronutrients and major cations and their potential relationships with bioaccumulation of trace elements. The authors analyzed the concentrations of macronutrients (C, N, P, S), major cations (Na, Mg, K, Ca), and trace elements (Al, V, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Pb) in the whole soft tissues of marine mussels Mytilus edulis and Perna viridis collected globally from 21 sites. The results showed that 12% to 84% of the variances in the trace elements was associated with major cations, and the tissue concentration of major cations such as Na and Mg in mussels was a good proxy for ambient seawater concentrations of the major cations. Specifically, bioaccumulation of most of the trace elements was significantly associated with major cations, and the relationships of major cations with trace cations and trace oxyanions were totally opposite. Furthermore, 14% to 69% of the variances in the trace elements were significantly associated with macronutrients. Notably, more than half of the variance in the tissue concentrations of As, Cd, V, Ba, and Pb was explained by the variance in macronutrients in one or both species. Because the tissue macronutrient concentrations were strongly associated with animal growth and reproduction, the observed coupling relationships indicated that these biological processes strongly influenced the bioaccumulation of some trace elements. The present study indicated that simultaneous quantification of macronutrients and major cations with trace elements can improve the interpretation of biomonitoring data. © 2015 SETAC.

  8. FT-IR spectroscopic study on the hofmann-Td type complex: M(4-Phenylpyridine)2M'(CN)4 (M=Ni; M'=Cd)

    International Nuclear Information System (INIS)

    Parlak, C.

    2005-01-01

    New Hofmann-Td type complex in the form of M(4-Phenylpyridine) 2 M'(CN) 4 (M = Ni, M' = Cd) was prepared in powder form and its infrared spectra is reported in the region of 4000-200 cm-1. From the spectral findings, this compound is similar in structure to the Hofmann-Td type complexes

  9. Studies on MgNi-Based Metal Hydride Electrode with Aqueous Electrolytes Composed of Various Hydroxides

    Directory of Open Access Journals (Sweden)

    Jean Nei

    2016-08-01

    Full Text Available Compositions of MgNi-based amorphous-monocrystalline thin films produced by radio frequency (RF sputtering with a varying composition target have been optimized. The composition Mg52Ni39Co3Mn6 is identified to possess the highest initial discharge capacity of 640 mAh·g−1 with a 50 mA·g−1 discharge current density. Reproduction in bulk form of Mg52Ni39Co3Mn6 alloy composition was prepared through a combination of melt spinning (MS and mechanical alloying (MA, shows a sponge-like microstructure with >95% amorphous content, and is chosen as the metal hydride (MH alloy for a sequence of electrolyte experiments with various hydroxides including LiOH, NaOH, KOH, RbOH, CsOH, and (C2H54N(OH. The electrolyte conductivity is found to be closely related to cation size in the hydroxide compound used as 1 M additive to the 4 M KOH aqueous solution. The degradation performance of Mg52Ni39Co3Mn6 alloy through cycling demonstrates a strong correlation with the redox potential of the cation in the alkali hydroxide compound used as 1 M additive to the 5 M KOH aqueous solution. NaOH, CsOH, and (C2H54N(OH additions are found to achieve a good balance between corrosion and conductivity performances.

  10. Synthesis and properties of A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) materials for environmental applications

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Anderson, E-mail: anderson_dias@iceb.ufop.br [Departamento de Quimica, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, ICEB II, Sala 67, Ouro Preto-MG, 35400-000 (Brazil); Cunha, Lumena; Vieira, Andiara C. [Departamento de Quimica, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, ICEB II, Sala 67, Ouro Preto-MG, 35400-000 (Brazil)

    2011-09-15

    Highlights: {yields} A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) materials were synthesized. {yields} Chemical synthesis produced different levels of crystallinity and ordering degree. {yields} Structural investigation by Raman scattering revealed a complex band structure. {yields} A strong correlation between band structure and ionic radius was determined. -- Abstract: Double layered hydroxide materials of composition A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) were synthesized by chemical precipitation at 60 {sup o}C. Different levels of crystallinity and ordering degree were observed depending upon the chemical environment or the combination between divalent and trivalent cations. The results from high-resolution transmission electron microscopy revealed that nanostructured layered samples were obtained with interplanar spacing compatible with previous literature. Raman scattering was employed to investigate the complex band structure observed, particularly the lattice vibrations at lower frequencies, which is intimately correlated to the cationic radius of both divalent and trivalent ions. The results showed that strongly coordinated water and chloride ions besides highly structured hydroxide layers have a direct influence on the stability of the hydrotalcites. It was observed that transition and decomposition temperatures varied largely for different chemical compositions.

  11. Synthesis, structural studies and antimicrobial activity of N'-((2Z, 3E)-3-(hydroxyimino)butan-2-ylidene)-2-phenylacetohydrazide and its Co(II), Ni(II) complexes

    Science.gov (United States)

    Karadeniz, Şeyma; Ataol, Cigdem Yuksektepe; Şahin, Onur; İdil, Önder; Bati, Hümeyra

    2018-06-01

    A new aroylhydrazoneoxime, N'-((2Z, 3E)-3-(hydroxyimino)butan-2-ylidene)-2-phenylacetohydrazide ligand (LH2) and its Ni(II) and Co(II) complexes, have been synthesized and characterized by elemental and thermal analyses, IR and UV-vis spectroscopy, magnetic moment and X-ray diffraction. The antimicrobial activities of these compounds were tested by using minimal inhibitory concentration method (MIC). The ligand-containing aroylhydrazone and oxime groups and its Ni complex crystallize in the triclinic system and P 1 - space group, while its Co complex crystallizes in the monoclinic system and the C 2/c space group. X-ray results show that the ligand in the keto form is transformed into enolic form when it forms coordination. From elemental analysis data, the stoichiometry of Co(II) complex was found to be 1:2 (metal/ligand), but 1:1 for Ni(II). IR spectra indicate that the ligand acts as monoanionic NNO- tridentate and coordination takes place form through the oxime nitrogen, imine nitrogen, and enolate oxygen atoms.

  12. Selective crystallization of cations with crown ethers

    International Nuclear Information System (INIS)

    Heffels, Dennis Egidius

    2014-01-01

    The aim of this work was to study the selectivity and preferences of the incorporation of differently sized cations in the cavities of various crown ethers and the characterization of the resulting compounds. The coordination preferences of crown ethers with different cavities have long been known, and the impact of other effects on the structure formation have increasingly become the focus of attention. In this work a comparative overview of the coordination preferences depending on various factors was undertaken. The focus was mainly on the variation of the cavity of the crown ether in the presence of differently sized cations. In addition, the effects of the solvent and differently coordinating anions have been investigated. Within the framework of this work, basic coordination preferences could be detected with rare earth nitrates, which are affected particularly by the choice of the solvent. The formation of different types of structures could be controlled by varying the conditions such that the incorporation of the cation in the cavity of the crown ether was influenced and the formation of a particular type of structure can be influenced partly by the choice of solvent. In this case no direct preferences for the incorporation into the cavity of the crown ether in relation to the cation size were observed for rare earth cations. However, the coordination of the crown ether leads in each case - for lanthanides - to rather high coordination numbers. A total of five new rare earth complexes and two structural variants could be observed with crown ethers. In the study of the selectivity of the incorporation into the cavity, known structures were also reproduced and further structures were characterized but the crystal structures not entirely solved. With the use of monovalent cations such as potassium, lithium or silver a total of nine new compounds could be synthesized, while no clear preferences for the incorporation of certain cations were detected. The

  13. Synthesis, spectroscopic, thermal and structural properties of 4-(2-aminoethyl)pyridinium tetracyanometallate(II) complexes

    Science.gov (United States)

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla; Şenyel, Mustafa; Şahin, Onur

    2017-05-01

    In this study, three new complexes (4aepyH)2[Ni(CN)4] (1), (4aepyH)2[Pd(CN)4] (2) and (4aepyH)2[Pt(CN)4] (3) [4aepy = 4-(2-aminoethyl)pyridine] have been synthesized and characterized by elemental, thermal, vibrational (FT-IR and Raman) and single-crystal X-ray diffraction techniques. The crystallographic analyses reveal that the complexes crystallize in the monoclinic system, space group C2/c. The asymmetric units of the complexes contain one M(II) ion, two cyanide ligands and one non-coordinated the 4aepy ligand. Each M(II) ion is four coordinated with four cyanide-carbon atoms in a square planar geometry and the [M(CN)4]2- anions act as a counter ion. The 4aepyH cations in the complexes compose of the protonation of the 4aepy. The vibrational spectral data also supported to the crystal structures of the complexes. Thermal stabilities and decomposition products of the complexes were investigated in the temperature range 40-700 °C in the static air atmosphere.

  14. Coordination behavior of tetraaza [N4] ligand towards Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes: Synthesis, spectroscopic characterization and anticancer activity

    Science.gov (United States)

    El-Boraey, Hanaa A.

    2012-11-01

    Novel eight Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes with [N4] ligand (L) i.e. 2-amino-N-{2-[(2-aminobenzoyl)amino]ethyl}benzamide have been synthesized and structurally characterized by elemental analysis, spectral, thermal (TG/DTG), magnetic, and molar conductivity measurements. On the basis of IR, mass, electronic and EPR spectral studies an octahedral geometry has been proposed for Co(II), Ni(II) complexes and Cu(II) chloride complex, square-pyramidal for Cu(I) bromide complex. For Cu(II) nitrate complex (6), Pd(II) complex (8) square planar geometry was proposed. The EPR data of Cu(II) complexes in powdered form indicate dx2-y2 ground state of Cu(II) ion. The antitumor activity of the synthesized ligand and some selected metal complexes has been studied. The palladium(II) complex (8) was found to display cytotoxicity (IC50 = 25.6 and 41 μM) against human breast cancer cell line MCF-7 and human hepatocarcinoma HEPG2 cell line.

  15. Ion backscattering, channeling and nuclear reaction analysis study of passive films formed on FeCrNi and FeCrNiMo (100) single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, C; Schmaus, D [Paris-7 Univ., 75 (France). Groupe de Physique des Solides de l' ENS; Elbiache, A; Marcus, P [Ecole Nationale Superieure de Chimie, 75 - Paris (France)

    1990-01-01

    The compositions of passive films formed on Fe-17Fr-13Ni (at. %) and Fe-18.5Cr-14Ni-1.5Mo (100) single crystals have been determined and the structure of the alloy under the film has been investigated. The alloys were passivated in 0.05M H{sub 2}SO{sub 4} at 250 mV/SHE for 30 min. The oxygen content was measured by nuclear microanalysis using the {sup 16}O(d,p) {sup 17}O* reaction. The oxygen content in the passive film is similar for the two alloys and equal to (12{plus minus}2) 10{sup 15} O/cm{sup 2}. The cationic compositions of the passive films have been determined by {sup 4}He channeling at two incident beam energies: 0.8 and 2.0 MeV. For the two alloys studied, a total cation content of (5{plus minus}2)10{sup 15} at/cm{sup 2} is found in the passive films. The corresponding thickness is about 12 A. There is an excess of oxygen, which can be attributed to the presence of hydroxyls and sulfate. A strong chromium enrichment is found in the passive film formed on both alloys: chromium represents about 50% of the cations. There is no evidence of molybdenum enrichment in the passive film formed on the Mo-alloyed stainless steel. The comparison of the results obtained at the two different incident beam energies (0.8MeV and 2MeV) reveals the existence of defects at the alloy/passive film interface. (author).

  16. Cationic Phosphorus Dendrimer Enhances Photodynamic Activity of Rose Bengal against Basal Cell Carcinoma Cell Lines.

    Science.gov (United States)

    Dabrzalska, Monika; Janaszewska, Anna; Zablocka, Maria; Mignani, Serge; Majoral, Jean Pierre; Klajnert-Maculewicz, Barbara

    2017-05-01

    In the last couple of decades, photodynamic therapy emerged as a useful tool in the treatment of basal cell carcinoma. However, it still meets limitations due to unfavorable properties of photosensitizers such as poor solubility or lack of selectivity. Dendrimers, polymers widely studied in biomedical field, may play a role as photosensitizer carriers and improve the efficacy of photodynamic treatment. Here, we describe the evaluation of an electrostatic complex of cationic phosphorus dendrimer and rose bengal in such aspects as singlet oxygen production, cellular uptake, and phototoxicity against three basal cell carcinoma cell lines. Rose bengal-cationic dendrimer complex in molar ratio 5:1 was compared to free rose bengal. Obtained results showed that the singlet oxygen production in aqueous medium was significantly higher for the complex than for free rose bengal. The cellular uptake of the complex was 2-7-fold higher compared to a free photosensitizer. Importantly, rose bengal, rose bengal-dendrimer complex, and dendrimer itself showed no dark toxicity against all three cell lines. Moreover, we observed that phototoxicity of the complex was remarkably enhanced presumably due to high cellular uptake. On the basis of the obtained results, we conclude that rose bengal-cationic dendrimer complex has a potential in photodynamic treatment of basal cell carcinoma.

  17. Magnetic and electrical transport properties of perovskite manganites Pr0.6Sr0.4MxMn1-xO3 (M = Fe, Co, Ni

    Directory of Open Access Journals (Sweden)

    X. S. Ge

    2017-12-01

    Full Text Available Powder samples of ABO3 perovskite manganites with the composition Pr0.6Sr0.4MxMn1-xO3 (M=Fe, Co, or Ni, 0.00≤x≤0.25 were synthesized using the sol-gel method. X-ray diffraction analyses showed that all three sets of samples had a single phase with an orthorhombic structure. The magnetic moment, μobs, of the samples at 10 K, decreased slowly for x≤0.10, whereas μobs decreased rapidly for x≥0.10. The dependences of μobs on the doping level x for the three series of samples were fitted successfully. In the fitting process, Mn, Fe, Co, and Ni cations were assumed to be trivalent, and the magnetic moment directions of Fe3+, Co3+, and Ni3+ cations were assumed to be canted antiferromagnetically coupled with Mn3+ cations. The cant angle ϕ decreased with the increase in x for x≤0.10 for Fe- and Ni-doped (x≤0.15 for Co-doped samples and increased rapidly when x≥0.10 (x≥0.15 for Co-doped samples. These properties are discussed using an oxygen 2p itinerant electron model, which is very similar to the oxygen 2p hole model proposed by Alexandrov et al. [Phys. Rev. Lett. 96, 117003 (2006].

  18. Cationic Pd(II-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

    Directory of Open Access Journals (Sweden)

    Takashi Nishikata

    2016-05-01

    Full Text Available Cationic palladium(II complexes have been found to be highly reactive towards aromatic C–H activation of arylureas at room temperature. A commercially available catalyst [Pd(MeCN4](BF42 or a nitrile-free cationic palladium(II complex generated in situ from the reaction of Pd(OAc2 and HBF4, effectively catalyzes C–H activation/cross-coupling reactions between aryl iodides, arylboronic acids and acrylates under milder conditions than those previously reported. The nature of the directing group was found to be critical for achieving room temperature conditions, with the urea moiety the most effective in promoting facile coupling reactions at an ortho C–H position. This methodology has been utilized in a streamlined and efficient synthesis of boscalid, an agent produced on the kiloton scale annually and used to control a range of plant pathogens in broadacre and horticultural crops. Mechanistic investigations led to a proposed catalytic cycle involving three steps: (1 C–H activation to generate a cationic palladacycle; (2 reaction of the cationic palladacycle with an aryl iodide, arylboronic acid or acrylate, and (3 regeneration of the active cationic palladium catalyst. The reaction between a cationic palladium(II complex and arylurea allowed the formation and isolation of the corresponding palladacycle intermediate, characterized by X-ray analysis. Roles of various additives in the stepwise process have also been studied.

  19. Complexing and analysis of cation selectivity of neutral phosphoryl-containing tripodaud of tris((0-diphenyl-phosphinoylmethyl)phenoxyethyl)amine to lithium sodium and potassium, in acetonitrile. Lithium selectivity and polymeclear compleses

    International Nuclear Information System (INIS)

    Baulin, V.E.; Solov'ev, V.P.; Strakhova, N.N.; Kazachenko, V.P.

    1996-01-01

    A new phosphoryl-containing tripodand-tris-[(0-diphenyl-phosphinoylmethyl)phenoxyethyl] amine-was synthesized. Constants of stability, enthalpy and entropy of reactions of tripodond complexing with lithium, sodium, potassium thiocyanates in acetonitrile at 298 k were determined. Investigation of complexing by the methods of calorimetry, 7 Li and 23 Na NMR, mass-spectrometry enabled to conclude that ligand formed polynuclear complexes with lithium thiocyanate of 2/1 and 3/1 composition along with 1/1 complex. High selectivity of podand to lithium cation in acetonitrile was conditioned by formation of polynuclear complexes. Refs. 29, figs. 3

  20. Synthetic cation-selective nanotube: permeant cations chaperoned by anions.

    Science.gov (United States)

    Hilder, Tamsyn A; Gordon, Dan; Chung, Shin-Ho

    2011-01-28

    The ability to design ion-selective, synthetic nanotubes which mimic biological ion channels may have significant implications for the future treatment of bacteria, diseases, and as ultrasensitive biosensors. We present the design of a synthetic nanotube made from carbon atoms that selectively allows monovalent cations to move across and rejects all anions. The cation-selective nanotube mimics some of the salient properties of biological ion channels. Before practical nanodevices are successfully fabricated it is vital that proof-of-concept computational studies are performed. With this in mind we use molecular and stochastic dynamics simulations to characterize the dynamics of ion permeation across a single-walled (10, 10), 36 Å long, carbon nanotube terminated with carboxylic acid with an effective radius of 5.08 Å. Although cations encounter a high energy barrier of 7 kT, its height is drastically reduced by a chloride ion in the nanotube. The presence of a chloride ion near the pore entrance thus enables a cation to enter the pore and, once in the pore, it is chaperoned by the resident counterion across the narrow pore. The moment the chaperoned cation transits the pore, the counterion moves back to the entrance to ferry another ion. The synthetic nanotube has a high sodium conductance of 124 pS and shows linear current-voltage and current-concentration profiles. The cation-anion selectivity ratio ranges from 8 to 25, depending on the ionic concentrations in the reservoirs.

  1. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism

    OpenAIRE

    Boughlala, Z.; Guerra, C.F.; Bickelhaupt, F.M.

    2016-01-01

    Abstract We have analyzed the structure and bonding of gas?phase Cl?X and [HCl?X]+ complexes for X+=?H+, CH3 +, Li+, and Na+, using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl? and HCl for the various cations. The Cl?X bond becomes longer and weaker along X+?=?H+, CH3 +, Li+, and Na+. Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence ...

  2. Synthesis of some (eta-arene)dihydridorhenium cations and their reactions with LiAlH4 and LiAlD4

    International Nuclear Information System (INIS)

    Baudrey, D.; Boydell, P.; Ephritikhine, M.

    1986-01-01

    A series of cations [Re(eta-arene)H 2 (PPh 3 ) 2 ] + (arene benzene, toluene, p-xylene, or mesitylene) was prepared from the corresponding neutral dihydridocyclohexadienyl complexes by treatment with CPh 3 BF 4 . These cations reacted with LiAlH 4 and LiAlD 4 to form dihydridocyclohexadienyl complexes. The unusual selectivity of the hydride attack is explained by steric interactions between the ring methyl groups and the bulky phosphine ligands. The initial product of the reaction of the eta-mesitylene cation with LiAlD 4 allows the isomerisation mechanism for the cyclohexadienyl complexes to be clarified. (author)

  3. Synthesis of cationic diphosphine ruthenium complexes with nido-dicarbaundecaborate anions. Molecular structure of [RuCl(dppe)2]+[7,8-nido-C2B9H12]-

    International Nuclear Information System (INIS)

    Cheredilin, D.N.; Dolgushin, F.M.; Balagurova, E.V.; Godovikov, I.A.; Chizhevskij, I.T.

    2004-01-01

    Five new diphosphine ruthenium(II) complexes with nido-dicarbaundecaborate anions were synthesized. The composition and structure of the complexes were confirmed by data of 1 H, 31 P{ 1 H} NMR and elementary analysis. The crystal and molecular structure of solvated complex [RuCl(dppe) 2 + [7,8-nido-C 2 B 9 H 12 ] - ·CH 2 Cl 2 was ascertained by the method of X-ray diffraction analysis. It is shown that coordination sphere of ruthenium atom in the complex cation is a distorted trigonal bipyramid. The distances from ruthenium atom to phosphorus atoms are 2.398(1) and 2.391(1) A, while the angle P-Ru-P equals 175.85(5) Deg [ru

  4. Evaluation of Iron Nickel Oxide Nanopowder as Corrosion Inhibitor: Effect of Metallic Cations on Carbon Steel in Aqueous NaCl

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhry, A. U.; Mishra, Brajendra [Colorado School of Mines, Denver (United States); Mittal, Vikas [The Petroleum Institute, Abu Dhabi (United Arab Emirates)

    2016-01-15

    The aim of this study was to evaluate the use of iron-nickel oxide (Fe{sub 2}O{sub 3}.NiO) nanopowder (FeNi) as an anti-corrosion pigment for a different application. The corrosion protection ability and the mechanism involved was determined using aqueous solution of FeNi prepared in a corrosive solution containing 3.5 wt.% NaCl. Anti-corrosion abilities of aqueous solution were determined using electrochemical impedance spectroscopy (EIS) on line pipe steel (API 5L X-80). The protection mechanism involved the adsorption of metallic cations on the steel surface forming a protective film. Analysis of EIS spectra revealed that corrosion inhibition occurred at low concentration, whereas higher concentration of aqueous solution produced induction behavior.

  5. Electrochemical investigations on cation-cation interaction between Np(V) and U(VI) in nitric acid medium

    International Nuclear Information System (INIS)

    Verma, P.K.; Murali, M.S.; Pathak, P.N.; Mohapatra, P.K.

    2014-01-01

    Ever since the first report on cation-cation interactions (CCIs) in 1961 by Sullivan et al., many researchers have worked on this using different techniques like optical spectroscopy and potentiometry. However, there is almost no report, in recent times, on this interesting subject using an electrochemical technique. In the present work, we set out to use simple cyclic voltammetry (CV) as a probe to study this phenomenon in the case of Np(V)-U(VI) in nitric acid medium. Accordingly, cyclic voltammograms were recorded individually for Np(V) , U(VI) in 4M HNO 3 and for solutions resulting from a titration of Np(V) with incremental additions of U(VI) in the same medium. These experiments were carried out using AutoLab 30 with three solid electrode system. Ag/AgCl was the reference electrode while Pt wires were used as working and counter electrode. The paper gives the part of CVs for successive additions of only U(VI) (1.4M) at fixed scan rate and room temperature. It can be seen that that the reduction peak shifts only slightly towards left with increased aliquots of U(VI). In contrast, the paper also gives the part of CVs for only U(VI) and for a titration mixture of fixed concentration of Np(V) and successive volume aliquot-additions of U(VI). It can be seen that there was no appreciable shift in the cathodic peak (∼ -0.15V) for additions of 1225μL of only U(VI) and 3225 μL of U(VI) in presence of Np. This showed that no change occurred till this composition. But with the addition of next aliquot of 4225μL of U(VI), there was an appreciable shift in the peak. This signified the formation of a new complex which can be attributed to the cation-cation interaction envisaged for Np(V)-U(VI). With further addition of an aliquot of 4725 μL of U(VI), it can be seen that again there was no appreciable shift in the cathodic peak position which probably underlined that the formation of the complex was complete

  6. Hexagonal perovskites with cationic vacancies. 23. Rhombohedral 12 L stacking polytypes of type Ba/sub 3/LaBsup(II)Resup(VII)Wsup(VI)vacantO/sub 12/ with Bsup(II) = Mg, Co, Ni, Cu, Zn

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, M; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-11-01

    The rhombohedral 12 L pervoskites with cationic vacancies of type Ba/sub 3/LaBsup(II)ReWvacantO/sub 12/ with Bsup(II) = Mg, Co, Ni, Cu, Zn are isotypic. According to intensity calculations on powder patterns of Ba/sub 3/LaZnReWvacantO/sub 12/ the series crystallize in the space group R-3m with the sequence (hhcc)/sub 3/; the refined, intensity related R' value is 5.7%. The octahedral net consists of blocks of three face connected octahedra with central void (ReWvacantO/sub 12/ units), which are linked via common corners through single octahedra, occupied by zinc.

  7. A Bis-Triazacyclononane Tris-Pyridyl N9 -Azacryptand "Beer Can" Receptor for Complexation of Alkali Metal and Lead(II) Cations.

    Science.gov (United States)

    Brown, Asha; Bunchuay, Thanthapatra; Crane, Christopher G; White, Nicholas G; Thompson, Amber L; Beer, Paul D

    2018-04-18

    A new bis-triazacyclononane tris-pyridyl N 9 -azacryptand ligand is prepared via a convenient one-pot [2+3] condensation reaction between triazacyclononane and 2,6-bis(bromomethyl) pyridine in the presence of M 2 CO 3 (M=Li, Na, K). The proton, lithium, sodium, potassium and lead(II) complexes of the ligand are characterised in the solid state. Preliminary solution-phase competition experiments indicate that the cryptand ligand preferentially binds lead(II) in the presence of sodium, calcium, potassium and zinc cations in methanol solution. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Biodistribution of radioactive organocations and cationic technetium complexes - implications to the uptake mechanism of potential heart-affine radiopharmaceuticals

    International Nuclear Information System (INIS)

    Muenze, R.; Shyre, R.; Seifert, S.; Guethert, I.; Kretschmar, M.; Kampf, G.; Knop, G.; Mohnike, W.; Schmidt, J.

    1986-01-01

    The biodistribution of various 14 C labeled organocations (ammonium, phosphonium) and cationic technetium complexes (TcCl 2 DMPE 2 ,TcDMPE 3 + ) was studied in rats to find potential relations between the chemical composition, structure, molecular size, lipophilicity and heart uptake. All of the radioactive cations were distributed in a similar manner, but with different biokinetics. Molecules containing several electronegative atoms in their ligand structure, e.g. nitrogen or oxygen which enhance polarity, were rapidly accumulated, but washed out again with resultant transient and diminished heart uptake. More highly lipophilic materials, by contrast, showed more extensive accumulation and persistent retention in the heart. The effect of human serum albumin on heart uptake was studied in a perfused heart model. Strong albumin binding prevented extensive heart uptake. This undesirable effect was neutralized by adding detergents to the perfusion bath. Evidence from these animal experiments was considered in the development of a new heart-seeking technetium compound (Tc-DPO), which is characterized by rapid accumulation in the human heart and substantially delayed washout. Heart images with minimal overlap of the inferoposterior wall and the right liver lobe were available in no more than 10 minutes p.i. in both planar and SPECT modes. A deficit in the inferior region was much more clearly defined than on the corresponding Thallium image. (Author)

  9. Why does the disorder of R-pn and rac-pn ligands in the quasi-one-dimensional bromo-bridged NiIII complexes, [Ni(pn)2Br]Br2 (pn=1,2-diaminopropane) afford similar STM patterns?

    Science.gov (United States)

    Wu, Hashen; Kawakami, Daisuke; Sasaki, Mari; Xie, Jimin; Takaishi, Shinya; Kajiwara, Takashi; Miyasaka, Hitoshi; Yamashita, Masahiro; Matsuzaki, Hiroyuki; Okamoto, Hiroshi

    2007-09-03

    The disordered patterns of R- and rac-1,2-diaminopropane (pn) in quasi-one-dimensional bromo-bridged Ni(III) complexes, [NiIII(pn)2Br]Br2, have been investigated by single-crystal X-ray structure determination and scanning tunneling microscopy (STM). X-ray structure determination shows that the methyl moieties are disordered on the right- and left-hand sides with half occupancies in both compounds, while the carbon atoms of the ethylene moieties of pn ligands are disordered in [Ni(rac-pn)2Br]Br2 and not disordered in [Ni(R-pn)2Br]Br2. In the STM images of both compounds, the bright spots are not straight but fluctuated with the similar patterns. We have concluded that tunnel current from the STM tip to metal ions are detected via methyl groups of pn ligands.

  10. Analysis of Native-Like Proteins and Protein Complexes Using Cation to Anion Proton Transfer Reactions (CAPTR)

    Science.gov (United States)

    Laszlo, Kenneth J.; Bush, Matthew F.

    2015-12-01

    Mass spectra of native-like protein complexes often exhibit narrow charge-state distributions, broad peaks, and contributions from multiple, coexisting species. These factors can make it challenging to interpret those spectra, particularly for mixtures with significant heterogeneity. Here we demonstrate the use of ion/ion proton transfer reactions to reduce the charge states of m/ z-selected, native-like ions of proteins and protein complexes, a technique that we refer to as cation to anion proton transfer reactions (CAPTR). We then demonstrate that CAPTR can increase the accuracy of charge state assignments and the resolution of interfering species in native mass spectrometry. The CAPTR product ion spectra for pyruvate kinase exhibit ~30 peaks and enable unambiguous determination of the charge state of each peak, whereas the corresponding precursor spectra exhibit ~6 peaks and the assigned charge states have an uncertainty of ±3%. 15+ bovine serum albumin and 21+ yeast enolase dimer both appear near m/ z 4450 and are completely unresolved in a mixture. After a single CAPTR event, the resulting product ions are baseline resolved. The separation of the product ions increases dramatically after each subsequent CAPTR event; 12 events resulted in a 3000-fold improvement in separation relative to the precursor ions. Finally, we introduce a framework for interpreting and predicting the figures of merit for CAPTR experiments. More generally, these results suggest that CAPTR strongly complements other mass spectrometry tools for analyzing proteins and protein complexes, particularly those in mixtures.

  11. Influence of biological media on the structure and behavior of ferrocene-containing cationic lipid/DNA complexes used for DNA delivery.

    Science.gov (United States)

    Golan, Sharon; Aytar, Burcu S; Muller, John P E; Kondo, Yukishige; Lynn, David M; Abbott, Nicholas L; Talmon, Yeshayahu

    2011-06-07

    Biological media affect the physicochemical properties of cationic lipid-DNA complexes (lipoplexes) and can influence their ability to transfect cells. To develop new lipids for efficient DNA delivery, the influence of serum-containing media on the structures and properties of the resulting lipoplexes must be understood. To date, however, a clear and general picture of how serum-containing media influences the structures of lipoplexes has not been established. Some studies suggest that serum can disintegrate lipoplexes formed using certain types of cationic lipids, resulting in the inhibition of transfection. Other studies have demonstrated that lipoplexes formulated from other lipids are stable in the presence of serum and are able to transfect cells efficiently. In this article, we describe the influence of serum-containing media on lipoplexes formed using the redox-active cationic lipid bis(n-ferrocenylundecyl)dimethylammonium bromide (BFDMA). This lipoplex system promotes markedly decreased levels of transgene expression in COS-7 cells as serum concentrations are increased from 0 to 2, 5, 10, and 50% (v/v). To understand the cause of this decrease in transfection efficiency, we used cryogenic transmission electron microscopy (cryo-TEM) and measurements of zeta potential to characterize lipoplexes in cell culture media supplemented with 0, 2, 5, 10, and 50% serum. Cryo-TEM revealed that in serum-free media BFDMA lipoplexes form onionlike, multilamellar nanostructures. However, the presence of serum in the media caused disassociation of the intact multilamellar lipoplexes. At low serum concentrations (2 and 5%), DNA threads appeared to separate from the complex, leaving the nanostructure of the lipoplexes disrupted. At higher serum concentration (10%), disassociation increased and bundles of multilamellae were discharged from the main multilamellar complex. In contrast, lipoplexes characterized in serum-free aqueous salt (Li(2)SO(4)) medium and in OptiMEM cell

  12. The role of different network modifying cations on the speciation of the Co2 + complex in silicates and implication in the investigation of historical glasses

    Science.gov (United States)

    Fornacelli, Cristina; Ceglia, Andrea; Bracci, Susanna; Vilarigues, Marcia

    2018-01-01

    In the last decades the speciation of the cobalt complex in a glass matrix has been extensively studied. Bivalent cobalt ions in glasses of different composition commonly adopt a tetrahedral coordination, though hexa- or penta-coordinated species are also possible. Changes in the absorbance spectrum of Co-doped glasses were attested in previous studies according to the introduction of different modifying cations. A shifting of the first sub-band characterizing the typical triplets of tetrahedral Co2 + ions in both the visible and near infrared regions was observed, but discrepancies in literature suggested a relevant role of glass composition on the definition of the optical signature of cobalt. Co-doped glasses with different composition (soda-lime, potash-lime, mixed alkali and ZnO-Na2O-CaO-SiO2) were studied via Fiber Optic Reflectance Spectroscopy (FORS). Pseudo-Voigt functions were used for the deconvolution of the absorbance spectra and the features of the bands characteristic of each cobalt complex were investigated. The structural role played by each modifying cation and the fundamental implications of glass basicity on the speciation of different Co-complexes were stressed. Changes in glass structure resulted in different equilibria between the three absorbing species whose specific optical signatures in the 480-530 nm region interact to determine the resulting absorbance spectrum.

  13. Synthesis, crystal structures, molecular docking and urease inhibition studies of Ni(II) and Cu(II) Schiff base complexes

    Science.gov (United States)

    Sangeeta, S.; Ahmad, K.; Noorussabah, N.; Bharti, S.; Mishra, M. K.; Sharma, S. R.; Choudhary, M.

    2018-03-01

    [Ni(L)2] 1 and [Cu(L)2] 2 [HL = 2-((E)-(2-methoxyphenylimino)methyl)-4,6-dichlorophenol] Schiff base complexes have been successfully synthesized and were characterized by FT-IR, UV-Vis, fluorescence spectroscopy and thermogravimetric analysis. The crystal structures of the two complexes were determined through X-ray crystallography. Its inhibitory activity against Helicobacter pylori urease was evaluated in vitro and showed strong inhibitory activity against H. pylori urease compared with acetohydroxamic acid (IC50 = 42.12 μmolL-1), which is a positive reference. A docking analysis using the AutoDock 4.0 program could explain the inhibitory activity of the complex against urease.

  14. Simple nonempirical calculations of the zero-field splitting in transition metal systems: I. The Ni(II)-water complexes

    International Nuclear Information System (INIS)

    Ribbing, C.; Odelius, M.; Laaksonen, A.; Kowalewski, J.; Roos, B.

    1990-01-01

    A simple nonempirical scheme is presented for calculating the splittings of ground state multiplets (the zero-field splitting) is transition metal complexes. The method employs single reference, single excitation CI calculations based on open-shell RHF. The spin-orbit coupling is described using an effective one-electron, one-center operators. The method is applied to the triplet state Ni(II) complexes with one to six water molecules. the validity of the second-order perturbation theory approach and of the spin-Hamiltonian formalism is found to be limited to slightly distorted octahedral systems. Generally, small changes in the geometries of the complexes are found to cause substantial variations of the splitting pattern

  15. Mass-spectrometric study of phosphorous amides and their Co(O), Mo(O), Ni(II), and Cu(I) complexes

    International Nuclear Information System (INIS)

    Nifant'ev, E.E.; Blokhin, Y.I.; Chikishev, Y.G.; Rozynov, B.V.; Teleshev, A.T.

    1985-01-01

    This article examines the performance of the mass-spectroscopic method in investigating allied comounds and original kigands. Apart from Cu(I) complexes, Co(O), Mo(O), and Ni(II) derivatives. The nature of the organophosphorus ligand is shown as having a substantial indluence on the structure of the cobalt complexes formed. The breakdown of the original ligands is accompanied by the initial breakage of the P-N bond. In the halide complexes first the metal is eliminated with the formation of the XhaL fragment, and the halogen is eliminated subsequently, but in the carbonyl derivatives the stagewise elimination of CO groups occurs with the subsequent elimination of the metal

  16. Synthesis and structure of 1,3-dimethyl-5-(p-sulfonamide-phenylazo)-6-aminouracil and its Ni(II) complex: Topological insights and investigation for noncovalent interactions

    Science.gov (United States)

    Debnath, Diptanu; Roy, Subhadip; Purkayastha, Atanu; Bauzá, Antonio; Choudhury, Rupasree; Ganguly, Rakesh; Frontera, Antonio; Misra, Tarun Kumar

    2017-08-01

    The azo-derivative, 1,3-dimethyl-5-(p-sulfonamide-phenylazo)-6-aminouracil (HL) containing 6-aminouracil (a biomolecule) and sulfonamide functionality (commonly found in sulfa-drugs), and its Ni(II) complex, NiIIL2 were synthesized. Single-crystal X-ray diffraction studies show that the ligand (HL) consists of an E conformation about the azo-linkage with a nearly planar geometry and the complex possesses distorted square planar geometry. The H-bonded underlying networks of HL and NiIIL2 were topologically classified revealing distinct topological types, namely tts and hxl, respectively. Moreover, topology of molecular packings in HL and NiIIL2 has also been discussed. Density functional theory (DFT) calculations, at the M06-2X/def2TZVP level of theory, are employed to characterize a great variety of non-covalent interactions that explicitly show the importance of antiparallel stacking interactions established by π--π+ interactions and H-bonds in the self-assembled dimmers in HL and lp-π/C-H⋯π interactions in NiIIL2. The results of NMR and UV-vis spectroscopies evidence that the ligand exists in hydrazone-imine-keto (B) tautomeric form in solution. The ligand absorption bands consist of the overlapping bands of π→π* and n→π* transitions. The complex experiences electronic transitions that consist of basically ILCT in character with some sort of participation of the atomic d-orbitals of the nickel. The pKa value of the ligand is found to be 4.09.

  17. Microemulsion based approach for nanospheres assembly into anisotropic nanostructures of NiMnO3 and their magnetic properties

    Science.gov (United States)

    Jha, Menaka; Kumar, Sandeep; Garg, Neha; Ramanujachary, Kandalam V.; Lofland, Samuel E.; Ganguli, Ashok K.

    2018-02-01

    The present study focuses on synthesis of anisotropic nanostructures of nickel manganese oxide (NiMnO3) obtained by thermal decomposition of nanocrystalline nickel manganese oxalate precursor, Ni0.5Mn0.5(C2O4)·2H2O which crystallized as nanorods. The synthesis of the oxalate precursor has been carried out via microemulsion-mediated process with cationic and non-ionic surfactants. The microemulsion led to reverse micelles, and the film flexibility of the micelle in presence of non-ionic surfactant (Tergitol) was reduced by increasing the chain length of the co-surfactant (1-butanol, 1-hexanol and 1-octanol) which led to the increase in reaction rate and hence increase in the aspect ratio of the nickel manganese oxalate by up to four times. However, in the presence of cationic surfactant, highly uniform nickel manganese oxalate nanorods were obtained. Further, the decomposition of the oxalate precursor was optimized to maintain the anisotropy of the rods of ternary metal oxide (NiMnO3). An electron microscopy study showed that the rods were made up of an assembly of ultrafine nanospheres. The NiMnO3 nanostructures were all ferrimagnetic with Curie temperature ranging between 437 and 467 K showing increasing saturation magnetization with increase in aspect ratio of the nanorods.

  18. Neutron diffraction study of the reduction of NiAl2O4

    International Nuclear Information System (INIS)

    Ustundag, E.; Clausen, B.; Bourke, M. A. M.

    2000-01-01

    The reduction of a solid NiAl 2 O 4 cylinder to a metal-ceramic composite consisting of Ni particles in an Al 2 O 3 matrix was monitored in situ at 1220 degree sign C with neutron powder diffraction. The reaction kinetics was determined with a time resolution of 30 min. The reduction is associated with a volume shrinkage. A comparison of finite element calculations and the changes in the measured lattice parameters suggests that creep has relaxed the residual strains that would otherwise result from the volume shrinkage. The data also indicate that structural evolution in unreduced NiAl 2 O 4 via a change in the cationic sublattice towards inverse spinel occurred and that led to a variation in lattice parameters. (c) 2000 American Institute of Physics

  19. Magnetic properties of Ni(II)-Mn(III) LDHs

    Energy Technology Data Exchange (ETDEWEB)

    Giovannelli, F., E-mail: fabien.giovannelli@univ-tours.fr [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France); Zaghrioui, M.; Autret-Lambert, C. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France); Delorme, F.; Seron, A. [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 Orleans Cedex 2 (France); Chartier, T.; Pignon, B. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France)

    2012-11-15

    The synthesis of Ni{sub 1-x}Mn{sub x}(OH){sub 2}(CO{sub 3}){sub x/2}{center_dot}nH{sub 2}O Layered Double Hydroxides (LDHs) for x = 0.2, 0.25 and 0.33, their characterisation by electron microscopy, X-ray diffraction and their magnetic properties are reported in this study. When x increases, the crystallinity of the nanoparticles is improved. The low temperature magnetic behaviour of these compounds is characteristic of the competition between in plane ferromagnetic and interlayer antiferromagnetic interactions. The ferromagnetism is due to in plane Ni cations interaction and decreases when manganese content increases (Tc decreases from 26 to 15 K when x increases from 0.2 to 0.33). It was found that the substitution of Ni by Mn ions favours the in plane antiferromagnetic order. This study demonstrates that magnetic interactions occur in LDH with non magnetic interlayer anions. -- Highlights: Black-Right-Pointing-Pointer The synthesis of Ni{sub 1-x}Mn{sub x}(OH){sub 2}(CO{sub 3}){sub x/2}{center_dot}nH{sub 2}O Layered Double Hydroxides have been performed. Black-Right-Pointing-Pointer The low temperature magnetic behaviour of these compounds has been studied. Black-Right-Pointing-Pointer The substitution of Ni by Mn ions favours the in plane antiferromagnetic order.

  20. Fe-solubility of Ni7S6 and Ni9S8: Thermodynamic analysis

    International Nuclear Information System (INIS)

    Waldner, P.

    2011-01-01

    Experimental data on phase equilibria have been used for thermodynamic analysis of the iron solubility of the nickel sulfides Ni 7 S 6 and Ni 9 S 8 . For both compounds, a two-sublattice approach within the framework of the compound energy formalism has been applied to perform Gibbs free energy modelling at 0.1 MPa total pressure consistently embedded in recent thermodynamic assessment studies of other iron-nickel-sulfides. The predicted maxima of iron solubility around 3 at% of Ni 7 S 6 and 5.5 at% of Ni 9 S 8 are confirmed by experimental data. The calculations of complex ternary phase relations with Fe-bearing Ni 7 S 6 and Ni 9 S 8 gain further improvement. The first internally consistent description of all thermodynamically stable phases known in the literature for the iron-nickel-sulfur system is completed.

  1. Cell number and transfection volume dependent peptide nucleic acid antisense activity by cationic delivery methods

    DEFF Research Database (Denmark)

    Llovera Nadal, Laia; Berthold, Peter; Nielsen, Peter E

    2012-01-01

    have now quantitatively compared the cellular activity (in the pLuc705 HeLa cell splice correction system) of PNA antisense oligomers using lipoplex delivery of cholesterol- and bisphosphonate-PNA conjugates, polyplex delivery via a PNA-polyethyleneimine conjugate and CPP delivery via a PNA......Efficient intracellular delivery is essential for high activity of nucleic acids based therapeutics, including antisense agents. Several strategies have been developed and practically all rely on auxiliary transfection reagents such as cationic lipids, cationic polymers and cell penetrating...... peptides as complexing agents and carriers of the nucleic acids. However, uptake mechanisms remain rather poorly understood, and protocols always require optimization of transfection parameters. Considering that cationic transfection complexes bind to and thus may up-concentrate on the cell surface, we...

  2. Electrospray ionization mass spectrometric investigations of the complexation behavior of macrocyclic thiacrown ethers with bivalent transitional metals (Cu, Co, Ni and Zn).

    Science.gov (United States)

    Tsybizova, Alexandra; Tarábek, Ján; Buchta, Michal; Holý, Petr; Schröder, Detlef

    2012-10-15

    Heavy metals are both a problem for the environment and an important resource for industry. Their selective extraction by means of organic ligands therefore is an attractive topic. The coordination of three thiacrown ethers to late 3d-metal ions was investigated by a combination of electrospray ionization mass spectrometry (ESI-MS) and electron paramagnetic resonance (EPR). The mass spectrometric experiments were carried out in an ion trap mass spectrometer with an ESI source. Absolute binding constants were estimated by comparison with data for 18-crown-6/Na(+). EPR spectroscopy was used as a complementary method for investigating the Cu(I) /Cu(II) redox couple. The study found that thiacrown ethers preferentially bind traces of copper even at an excess of other metal ions (Co(II), Ni(II), and Zn(II)). The absolute association constants of the Cu(I) complexes were about 10(8) M(-1), and about two orders of magnitude lower for the other 3d-metal cations. The EPR spectra demonstrated that the reduction from Cu(II) to Cu(I) upon formation of the [(thiacrown)Cu](+) species takes place in solution. ESI-MS demonstrated that the three thiacrown ligands examined had high binding constants as well as good selectivities for copper(I) at low concentrations, and in the presence of other metal ions. By a combination of ESI-MS and EPR spectrometry it was shown that the reduction from Cu(II) to Cu(I) occurred in solution. Copyright © 2012 John Wiley & Sons, Ltd.

  3. Intermolecular Dehydrative Coupling Reaction of Arylketones with Cyclic Alkenes Catalyzed by a Well-Defined Cationic Ruthenium-Hydride Complex: A Novel Ketone Olefination Method via Vinyl C–H Bond Activation

    Science.gov (United States)

    Yi, Chae S.; Lee, Do W.

    2010-01-01

    Summary The cationic ruthenium-hydride complex [(η6-C6H6)(PCy3)(CO)RuH]+BF4− was found to be a highly effective catalyst for the intermolecular olefination reaction of arylketones with cycloalkenes. The preliminary mechanistic analysis revealed that electrophilic ruthenium-vinyl complex is the key species for mediating both vinyl C–H bond activation and the dehydrative olefination steps of the coupling reaction. PMID:20567607

  4. Performance of Spent Mushroom Farming Waste (SMFW) Activated Carbon for Ni (II) Removal

    Science.gov (United States)

    Desa, N. S. Md; Ghani, Z. Ab; Talib, S. Abdul; Tay, C. C.

    2016-07-01

    The feasibility of a low cost agricultural waste of spent mushroom farming waste (SMFW) activated carbon for Ni(II) removal was investigated. The batch adsorption experiments of adsorbent dosage, pH, contact time, metal concentration, and temperature were determined. The samples were shaken at 125 rpm, filtered and analyzed using ICP-OES. The fifty percent of Ni(II) removal was obtained at 0.63 g of adsorbent dosage, pH 5-6 (unadjusted), 60 min contact time, 50 mg/L Ni(II) concentration and 25 °C temperature. The evaluated SMFW activated carbon showed the highest performance on Ni(II) removal compared to commercial Amberlite IRC86 resin and zeolite NK3. The result indicated that SMFW activated carbon is a high potential cation exchange adsorbent and suitable for adsorption process for metal removal. The obtained results contribute toward application of developed SMFW activated carbon in industrial pilot study.

  5. Synthesis of thiadiazolobenzamide via cyclization of thioxothiourea and its Ni and Pd complexes

    Directory of Open Access Journals (Sweden)

    Adhami Forogh

    2012-01-01

    Full Text Available In this study, the new compound, N-(3-methyl-4- oxo[1,3,4]thiadiazolo[2,3-c][1,2,4]triazin-7-yl benzamide, could be obtained via two different reactions: 1 reaction of 4-amino-6-Methyl-3- (Methylsulfanyl-1,2,4-triazin-5-one with benzoyl isothiocyanate under removal of methylmercaptane, 2 reaction of 4-amino-6-Methyl-3-thioxo- 1,2,4-triazin-5-one with benzoyl isothiocyanate under elimination of hydrogen sulfide. In both reactions a new bond between sulfur and nitrogen atoms was formed and a five-membered ring was created. The oxo thiadiazolo benzamide was characterized by IR-, 1HNMR- and 13CNMR spectroscopy as well as by Mass spectrometry. X-ray crystallography was used to shed light on the structure of this new compound. Two new complexes could be generated by coordination of oxo thiadiazolo benzamide to Pd(II and Ni(II ions. These complexes have been analyzed by IR-, 1HNMR- and 13CNMR spectroscopy, conductometry and Thermal gravimetry (TGA. Theoretical QM Calculation GIAO has also been applied to predict the structure of the Pd complex.

  6. Impact of metal cations on the electrocatalytic properties of Pt/C nanoparticles at multiple phase interfaces.

    Science.gov (United States)

    Durst, Julien; Chatenet, Marian; Maillard, Frédéric

    2012-10-05

    Proton-exchange membrane fuel cells (PEMFCs) use carbon-supported nanoparticles based on platinum and its alloys to accelerate the rate of the sluggish oxygen-reduction reaction (ORR). The most common metals alloyed to Pt include Co, Ni and Cu, and are thermodynamically unstable in the PEMFC environment. Their dissolution yields the formation and redistribution of metal cations (M(y+)) within the membrane electrode assembly (MEA). Metal cations can also contaminate the MEA when metallic bipolar plates are used as current collectors. In each case, the electrical performance of the PEMFC severely decreases, an effect that is commonly attributed to the poisoning of the sulfonic acid groups of the perfluorosulfonated membrane (PEM) and the resulting decrease of the proton transport properties. However, the impact of metal cations on the kinetics of electrochemical reactions involving adsorption/desorption and bond-breaking processes remains poorly understood. In this paper, we use model electrodes to highlight the effect of metal cations on Pt/C nanoparticles coated or not with a perfluorosulfonated ionomer for the CO electrooxidation reaction and the oxygen reduction reaction. We show that metal cations negatively impact the ORR kinetics and the mass-transport resistance of molecular oxygen. However, the specific adsorption of sulfonate groups of the Nafion® ionomer locally modifies the double layer structure and increases the tolerance to metal cations, even in the presence of sulphate ions in the electrolyte. The survey is extended by using an ultramicroelectrode with cavity and a solid state cell (SSC) specifically developed for this study.

  7. Bis[1-(3-cyanobenzylpyridinium] bis(1,2-dicyanoethene-1,2-dithiolatonickelate(II

    Directory of Open Access Journals (Sweden)

    Hai-Bao Duan

    2011-01-01

    Full Text Available In the ionic title complex, (C13H11N22[Ni(C4N2S22], the NiII ion is located on an inversion centre so the asymmetric unit contains one-half [Ni(mnt2]2− dianion (mnt2− is maleonitriledithiolate and one 1-(3-cyanobenzylpyridinium cation ([CNBzPy]+. The NiII ion in the [Ni(mnt2]2− anion is coordinated by four S atoms of two mnt2− ligands, and exhibits square-planar coordination geometry. In the [CNBzPy]+ cation, the benzene and pyridine rings are twisted with respect to the C/C/N plane incorporating the methylene C atom that links them. The crystal structure is stabilized by Coulombic interactions.

  8. AAg2M[VO4]2 (A=Ba,Sr; M=Co,Ni): A series of ferromagnetic insulators

    Science.gov (United States)

    Möller, Angela; Amuneke, Ngozi E.; Daniel, Phillip; Lorenz, Bernd; de la Cruz, Clarina R.; Gooch, Melissa; Chu, Paul C. W.

    2012-06-01

    AAg2M[VO4]2 with A=Sr2+ or Ba2+ present a series of layered compounds featuring a triangular lattice of transition metal cations, M = Co2+ or Ni2+, connected via nonmagnetic ortho-vanadates, which provide the magnetic superexchange within the layers. For this series of insulating compounds, ferromagnetic long-range order below 10 K is suggested by magnetization and specific heat measurements and confirmed by neutron diffraction experiments. We have investigated the impact of the spacer size of A2+ separating the layers leading to a tilting of the vanadates and consequently inducing a change in the effective magnetic correlations. Magnetization and specific heat measurements corroborate the important dependence of the magnetic superexchange on the orientation of the vanadates and the respective spin system. Furthermore, the ground state properties of the spin systems, S=1 (Ni2+) and S=3/2 (Co2+) in their respective octahedral coordination of oxygen, are evaluated. Calculated magnetic moments of the single ion complexes agree well with the magnetic structure. We, furthermore, report the dependence of Tc on applied isotropic pressure suggestive of a pressure effect on the effective ferromagnetic exchange coupling constants. In addition spectroscopic investigations probing the electronic structure of the [MO6] complexes and the vibrational structure of the [VO4] units are given.

  9. Di-μ-cyanido-tetra-cyanido(5,5,7,12,12,14-hexa-methyl-1,4,8,11-tetra-aza-cyclo-tetra-decane)[N-(quinolin-8-yl)quinoline-2-carboxamidato]diiron(III)nickel(II) 2.07-hydrate.

    Science.gov (United States)

    Yang, Yuqi; Zhou, Hongbo; Shen, Xiaoping

    2013-05-01

    The asymmetric unit of the title complex, [Fe2Ni(C19H12N3O)2(CN)6(C16H36N4)]·2.07H2O, contains one [Fe(qcq)(CN)3](-) anion, half a [Ni(teta)](2+) cation and two partially occupied inter-stitial water mol-ecules [qcq(-) is the N-(quinolin-8-yl)quinoline-2-carboxamidate anion and teta is 5,5,7,12,12,14-hexa-methyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-ne]. In the complex mol-ecule, two [Fe(qcq)(CN)3](-) anions additionally coordinate the central [Ni(teta)](2+) cation through cyanide groups in a trans mode, resulting in a trinuclear structure with the Ni(2+) cation lying on an inversion centre. The two inter-stitial water mol-ecules are partially occupied, with occupancy factors of 0.528 (10) and 0.506 (9). O-H⋯O and O-H⋯N hydrogen bonding involving the two lattice water molecules and the carbonyl function and a teta N atom in an adjacent cluster leads to the formation of layers extending parallel to (010).

  10. Thermolysis synthesis of pure phase NiO from novel sonochemical synthesized Ni(II) nano metal-organic supramolecular architecture.

    Science.gov (United States)

    Hanifehpour, Younes; Morsali, Ali; Mirtamizdoust, Babak; Joo, Sang Woo; Soltani, Behzad

    2017-07-01

    Nano-structures of a new supramolecular coordination compound of divalent nickel with the pyrazol (pzH) containing the terminal azide anions, [Ni(pzH) 2 (N 3 ) 2 ] (1), with discrete molecular architecture (DMA) in solid state was synthesized via sonochemical method. The new nanostructure was characterized by scanning electron microscopy, X-ray powder diffraction, IR, and elemental analysis. Compound 1 was structurally characterized by single crystal X-ray diffraction and the single-crystal X-ray data shows that the coordination number of Ni (II) ions is six, (NiN 6 ), with four N-donor atoms from neutral "pzH" ligands and two N-donors from two terminal azide anions. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The structure of the title complex was optimized by density functional theory calculations. Calculated structural parameters and IR spectra for the title complex are consistent with the crystal structure. The NiO nanoparticles were obtained by thermolysis of 1 at 180°C with oleic acid as a surfactant. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Interactions of nickel(II) with histones: enhancement of 2'-deoxyguanosine oxidation by Ni(II) complexes with CH3CO-Cys-Ala-Ile-His-NH2, a putative metal binding sequence of histone H3.

    Science.gov (United States)

    Bal, W; Lukszo, J; Kasprazak, K S

    1996-03-01

    Studies of 2'-deoxyguanosine oxidation by hydrogen peroxide in the presence of CH3CO-Cys-Ala-Ile-His-NH2 (CAIH) and/or NiCl2 have been carried out in 100 mM phosphate buffer (pH 7.4) at 37 degrees C. The dimeric CAIH oxidation product, CAIH disulfide, and its weak, octahedral Ni(II) complex, rather than the monomeric CAIH and its strong, square-planar Ni(II) complex, were found to be major catalysts of 8-oxo-2'-deoxyguanosine (8-oxo-dG) formation. The presence of Ni(II) largely enhanced 8-oxo-dG yield, especially at submillimolar concentrations of H2O2. The reaction was found not to involve detectable amounts of free radicals or Ni(III). These results, together with those published previously [Bal, W. et al. (1995) Chem. Res. Toxicol. 8, 683-692], lay a framework for the detailed investigations of the interactions of histone octamer with Ni(II) and other metal ions. They also suggest that molecular mechanisms of nickel carcinogenesis may involve oxidative damage processes catalyzed by weak Ni(II) complexes with cellular components.

  12. Crystal structure, DNA binding, cleavage, antioxidant and antibacterial studies of Cu(II), Ni(II) and Co(III) complexes with 2-((furan-2-yl)methylimino)methyl)-6-ethoxyphenol Schiff base

    Science.gov (United States)

    Venkateswarlu, Kadtala; Kumar, Marri Pradeep; Rambabu, Aveli; Vamsikrishna, Narendrula; Daravath, Sreenu; Rangan, Krishnan; Shivaraj

    2018-05-01

    Three novel binary metal complexes; 1 [Cu(L)2], 2 [Ni(L)2] and 3 [Co(L)3] where, L (2-(((furan-2-yl) methylimino)methyl)-6-ethoxyphenol, C14H15NO3), were synthesized and characterized by various spectral techniques. Based on spectral studies square planar geometry is assigned for Cu(II) and Ni(II) complexes, whereas Co(III) owned octahedral geometry. Ligand, [Cu(L)2] and [Ni(L)2] are crystallized and found to be monoclinic crystal systems. CT-DNA absorption binding studies revealed that the complexes show good binding propensity (Kb = 5.02 × 103 M-1, 2.77 × 103 M-1, 1.63 × 104 M-1 for 1, 2 and 3 respectively). The role of these complexes in the oxidative and photolytic cleavage of supercoiled pBR322 DNA was studied and found that the complexes cleave the pBR322 DNA effectively. The catalytic ability of 1, 2 and 3 follows the order: 3 > 1 >2. Antioxidant studies of the new complexes revealed that they exhibit significant antioxidant activity against DPPH radical. The Schiff base and its metal complexes have been screened for antibacterial studies by Minimum Inhibitory Concentration method. It is observed that all metal complexes showed more activity than free ligand.

  13. Radiation chemistry of aromatic dimer radical cations

    International Nuclear Information System (INIS)

    Okamoto, Kazumasa; Tagawa, Seiichi

    2009-01-01

    π-π Interactions of aromatic molecules are paid attention much in many fields, especially biology, chemistry, and applied physics, represented as protein, DNA, electron donor-accepter complexes, charge transfers, and self assembly molecules. Aromatic molecules including benzene rings are the simplest case to study the π-π interactions. To interpret the charge resonance (CR) structure in the dimer radical cations, spectroscopic and ESR methods have been carried out. The spectroscopic study on the dimer radical ion of molecules with two chromophores would be profitable to identify the electronic and configurational properties. In this article, dynamics of the dimer radical cation of benzenes, polystyrenes, and resist polymers is described on the basis of direct observation of CR band by the nanosecond pulse radiolysis and low temperature γ-radiolysis methods. (author)

  14. Synthesis, Spectral and Antimicrobial Studies of Some Co(II, Ni(II and Cu(II Complexes Containing 2-Thiophenecarboxaldehyde Moiety

    Directory of Open Access Journals (Sweden)

    A. P. Mishra

    2012-01-01

    Full Text Available Some new Schiff base metal complexes of Co(II, Ni(II and Cu(II derived from 3-chloro-4-fluoroaniline (HL1 and 4-fluoroaniline (HL2 with 2-thiophenecarboxaldehyde have been synthesized and characterized by elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, ESR and magnetic susceptibility. The complexes exhibit coordination number 4 or 6. The complexes are colored and stable in air. Analytical data revealed that all the complexes exhibited 1:2 (metal: ligand ratio. FAB-mass data show degradation pattern of the complexes. The Schiff base and metal complexes show a good activity against the bacteria; B. subtilis, E. coli and S. aureus and fungi A. niger, A. flavus and C. albicans. The antimicrobial results also indicate that the metal complexes are better antimicrobial agents as compared to the Schiff bases.

  15. Separation of cations of heavy metalsfrom concentrated galvanic drains

    Directory of Open Access Journals (Sweden)

    L. P. Bondareva

    2018-01-01

    Full Text Available When applying galvanic coatings, soluble salts of heavy metals such as iron, copper, nickel, zinc, cadmium, chromium and other metals are used, toxic cations enter the water, with subsequent migration to the biosphere. To date, many methods have been developed for cleaning galvanic sewage, which cannot be considered sufficiently effective. The joint sorption of divalent cations of copper, nickel and cadmium from concentrated aqueous solutions was investigated. Calculation and experimental methods were used to determine the separation conditions of the bivalent ion systems that differed and close in sorption properties on the aminophosphonic polyampholyte Purolite S950 in a natrium form. It is shown that the cadmium (II cations can be isolated from solutions containing copper (II or nickel (II cations even at the height of the sorption layer of 0.13 m due to the difference in the defining characteristics of the cations. This layer height can be used not only in a chromatographic column, but also in a concentrating cartridge. Separation of the copper (II and nickel (II close to the sorption properties requires an absorbing layer of 0.76 m, which can only be used in a chromatographic column, but not for a concentrating cartridge. In this paper, the degrees of ion separation in various sorption conditions are calculated. The applicability of the conductometric method for controlling the ion exchange process is shown not only when the free cations are isolated from aqueous solutions but also bound to complexes.

  16. Complexation of trivalent cationic lanthanides by N.O donor ligands: physico-chemical studies of the association and selectivity in solution

    International Nuclear Information System (INIS)

    Bravard, F.

    2004-01-01

    The aim of this work is to study the complexation of f-elements in solution by ligands incorporating N-heterocyclic donors. These ligands display interesting properties for the selective separation of An(III)/Ln(III) have been studied to obtain a better understanding of the coordination properties with f-elements and to develop more selective extractants. The hepta-dentate ligand tpaam shows an affinity for Ln(III) similar to the tetradentate ligand tpa in water even when the three additional amide groups are bonded to the metal. Even though the complexation with tpa is exothermic, that with tpaam is endothermic with a more positive entropy. The dehydration of the cation disfavours the formation of Ln(III) complexes with ligands containing weak donors. The analysis of the solution paramagnetic relaxation times of the tpaam complexes is in agreement with data in the solid-state. There is little difference between the formation constants of the Ln 3+ complexes with different ligands (tpaam, tpzen, tpa and tpza) as determined by UV-vis spectrophotometry in anhydrous acetonitrile. The limitations encountered during this study are intrinsic to the ligands studied. The preliminary study of two tetrapodal ligands containing acid and pyridine groups (L py )or pyrazine (L pz ) show the formation of 1:1 complexes in water. Analysis of the formation constants of the corresponding Gd(III) complexes shows that replacement of a pyridine group by pyrazine result in a loss of stability of 1.6 logarithmic units. (author) [fr

  17. Local structures in mixed LixFe1−yMyPO4 (M=Co, Ni) electrode materials

    International Nuclear Information System (INIS)

    Jalkanen, K.; Lindén, J.; Karppinen, M.

    2015-01-01

    We employ 57 Fe Mössbauer spectroscopy as a local tool to probe electrical environments of Fe 2+ and Fe 3+ at different lithiation (x) and cation-substitution (y) levels in Li x Fe 1−y M y PO 4 /C (M=Co, Ni) Li-ion battery electrode materials. Upon delithiation the local environment of Fe 3+ remains unaffected for the parent y=0 system due to the LiFePO 4 /FePO 4 phase separation, whereas for y>0 changes in the electrical environment are seen for Fe 3+ . When the Fe 2+ /Fe 3+ redox couple is partially-delithiated, a decreasing quadrupole splitting value is observed for Fe 3+ with increasing y, implying a more symmetric electrical environment. The increasing concentration of the Co 2+ /Ni 2+ substituent introduces increasing amounts of Li atoms in the Fe 3+ -containing phase, and these nearest-neighbor Li atoms are suspected to cause the changes seen in the local environment of Fe 3+ . - Graphical abstract: Local environment of iron in Li x Fe 1−y (Co/Ni) y PO 4 is studied by 57 Fe Mössbauer spectroscopy at different lithiation (x) and cation-substitution (y) levels. - Highlights: • Local Fe environment in Li x Fe 1−y (Co/Ni) y PO 4 is studied by 57 Fe Mössbauer spectroscopy. • Co/Ni-for-Fe substitution results in a more symmetric electrical environment for Fe 3+ . • Due to presence of Co 2+ /Ni 2+ , Li atoms are introduced into the Fe 3+ -containing phase. • These nearest-neighbor Li atoms are suggested to change the local Fe 3+ environment

  18. Synchronization and Causality Across Time-scales: Complex Dynamics and Extremes in El Niño/Southern Oscillation

    Science.gov (United States)

    Jajcay, N.; Kravtsov, S.; Tsonis, A.; Palus, M.

    2017-12-01

    A better understanding of dynamics in complex systems, such as the Earth's climate is one of the key challenges for contemporary science and society. A large amount of experimental data requires new mathematical and computational approaches. Natural complex systems vary on many temporal and spatial scales, often exhibiting recurring patterns and quasi-oscillatory phenomena. The statistical inference of causal interactions and synchronization between dynamical phenomena evolving on different temporal scales is of vital importance for better understanding of underlying mechanisms and a key for modeling and prediction of such systems. This study introduces and applies information theory diagnostics to phase and amplitude time series of different wavelet components of the observed data that characterizes El Niño. A suite of significant interactions between processes operating on different time scales was detected, and intermittent synchronization among different time scales has been associated with the extreme El Niño events. The mechanisms of these nonlinear interactions were further studied in conceptual low-order and state-of-the-art dynamical, as well as statistical climate models. Observed and simulated interactions exhibit substantial discrepancies, whose understanding may be the key to an improved prediction. Moreover, the statistical framework which we apply here is suitable for direct usage of inferring cross-scale interactions in nonlinear time series from complex systems such as the terrestrial magnetosphere, solar-terrestrial interactions, seismic activity or even human brain dynamics.

  19. Fluconazole affects the alkali-metal-cation homeostasis and susceptibility to cationic toxic compounds of Candida glabrata.

    Science.gov (United States)

    Elicharova, Hana; Sychrova, Hana

    2014-08-01

    Candida glabrata is a salt-tolerant and fluconazole (FLC)-resistant yeast species. Here, we analyse the contribution of plasma-membrane alkali-metal-cation exporters, a cation/proton antiporter and a cation ATPase to cation homeostasis and the maintenance of membrane potential (ΔΨ). Using a series of single and double mutants lacking CNH1 and/or ENA1 genes we show that the inability to export potassium and toxic alkali-metal cations leads to a slight hyperpolarization of the plasma membrane of C. glabrata cells; this hyperpolarization drives more cations into the cells and affects cation homeostasis. Surprisingly, a much higher hyperpolarization of C. glabrata plasma membrane was produced by incubating cells with subinhibitory concentrations of FLC. FLC treatment resulted in a substantially increased sensitivity of cells to various cationic drugs and toxic cations that are driven into the cell by negative-inside plasma-membrane potential. The effect of the combination of FLC plus cationic drug treatment was enhanced by the malfunction of alkali-metal-cation transporters that contribute to the regulation of membrane potential and cation homeostasis. In summary, we show that the combination of subinhibitory concentrations of FLC and cationic drugs strongly affects the growth of C. glabrata cells. © 2014 The Authors.

  20. Effects of inorganic acids and divalent hydrated metal cations (Mg(2+), Ca(2+), Co(2+), Ni(2+)) on γ-AlOOH sol-gel process.

    Science.gov (United States)

    Zhang, Jian; Xia, Yuguo; Zhang, Li; Chen, Dairong; Jiao, Xiuling

    2015-11-07

    In-depth understanding of the sol-gel process plays an essential role in guiding the preparation of new materials. Herein, the effects of different inorganic acids (HCl, HNO3 and H2SO4) and divalent hydrated metal cations (Mg(2+), Ca(2+), Co(2+), Ni(2+)) on γ-AlOOH sol-gel process were studied based on experiments and density functional theory (DFT) calculations. In these experiments, the sol originating from the γ-AlOOH suspension was formed only with the addition of HCl and HNO3, but not with H2SO4. Furthermore, the DFT calculations showed that the strong adsorption of HSO4(-) on the surface of the γ-AlOOH particles, and the hydrogen in HSO4(-) pointing towards the solvent lead to an unstable configuration of electric double layer (EDL). In the experiment, the gelation time sequence of γ-AlOOH sol obtained by adding metal ions changed when the ionic strength was equal to or greater than 0.198 mol kg(-1). The DFT calculations demonstrated that the adsorption energy of hydrated metal ions on the γ-AlOOH surface can actually make a difference in the sol-gel process.

  1. Effect of the competition of Cu(II) and Ni(II) on the kinetic and thermodynamic stabilities of Cr(III)-organic ligand complexes using competitive ligand exchange (EDTA).

    Science.gov (United States)

    Cunha, Graziele da Costa; Goveia, Danielle; Romão, Luciane Pimenta Cruz; de Oliveira, Luciana Camargo

    2015-05-01

    The effect of competition of Cu(II) and Ni(II) on the kinetic stability of Cr(III) complexed with natural organic matter (NOM) was characterized using EDTA exchange with single-stage tangential-flow ultrafiltration. For a water sample from Serra de Itabaiana, 3% of spiked Cr(III) was exchanged, while for a sample from the Itapanhaú River, 7, 10, 10, and 21% was exchanged in experiments using Cr(III) alone and in combination with Cu(II), Ni(II), or Cu(II) + Ni(II), respectively. Times required to reach exchange equilibrium with EDTA were less than 360 min. The influence of competition from Ni(II) and Cu(II) on the availability of complexed Cr(III) was low, demonstrating preference of the ligand sites for Cr(III). This was correlated with sample humification, as confirmed by EPR and (13)C NMR analyses. Exchange efficiency was in the order Cu > Ni > Cr, and the process could be readily described by first order kinetics, with average rate constants of 0.35-0.37 h(-1). Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Ternary complex of plasmid DNA with NLS-Mu-Mu protein and cationic niosome for biocompatible and efficient gene delivery: a comparative study with protamine and lipofectamine.

    Science.gov (United States)

    Nematollahi, Mohammad Hadi; Torkzadeh-Mahanai, Masoud; Pardakhty, Abbas; Ebrahimi Meimand, Hossein Ali; Asadikaram, Gholamreza

    2017-10-28

    Non-viral gene delivery methods are considered due to safety and simplicity in human gene therapy. Since the use of cationic peptide and niosome represent a promising approach for gene delivery purposes we used recombinant fusion protein and cationic niosome as a gene carrier. A multi-domain fusion protein including nuclear localization motif (NLS) and two DNA-binding (Mu) domains, namely NLS-Mu-Mu (NMM) has been designed, cloned and expressed in E. coli DE3 strain. Afterward, the interested protein was purified by affinity chromatography. Binary vectors based on protein/DNA and ternary vectors based on protein/DNA/niosome were prepared. Protamine was used as a control. DNA condensing properties of NMM and protamine were evaluated by various experiments. Furthermore, we examined cytotoxicity, hemolysis and transfection potential of the binary and ternary complexes in HEK293T and MCF-7 cell lines. Protamine and Lipofectamine™2000 were used as positive controls, correspondingly. The recombinant NMM was expressed and purified successfully and DNA was condensed efficiently at charge ratios that were not harmful to cells. Peptidoplexes showed transfection efficiency (TE) but ternary complexes had higher TE. Additionally, NMM ternary complex was more efficient compared to protamine ternary vectors. Our results showed that niosomal ternary vector of NMM is a promising non-viral gene carrier to achieve an effective and safe carrier system for gene therapy.

  3. Validation of site-specific soil Ni toxicity thresholds with independent ecotoxicity and biogeochemistry data for elevated soil Ni

    International Nuclear Information System (INIS)

    Hale, Beverley; Gopalapillai, Yamini; Pellegrino, Amanda; Jennett, Tyson; Kikkert, Julie; Lau, Wilson; Schlekat, Christian; McLaughlin, Mike J.

    2017-01-01

    The Existing Substances Regulation Risk Assessments by the European Union (EU RA) generated new toxicity data for soil organisms exposed to Ni added to sixteen field-collected soils with low background concentration of metals and varying physico-chemical soil characteristics. Using only effective cation exchange capacity (eCEC) as a bioavailability correction, chronic toxicity of Ni in soils with a wide range of characteristics could be predicted within a factor of two. The objective of the present study was to determine whether this was also the case for three independent data sets of Ni toxicity thresholds. Two of the data sets were from Community Based Risk Assessments in Port Colborne ON, and Sudbury ON (Canada) for soils containing elevated concentrations of Ni, Co and Cu arising from many decades of Ni mining, smelting and refining. The third data set was the Metals in Asia study of soluble Ni added to field soils in China. These data yielded 72 leached and aged EC 10 /NOEC values for soil Ni, for arthropods, higher plants and woodlot structure and function. These were reduced to nine most sensitive single or geometric mean species/function endpoints, none of which were lower than the HC 5 predicted for a soil with an eCEC of 20 cmol/kg. Most of these leached and aged EC 10 /NOEC values were from soils co-contaminated with Cu, in some cases at its median HC 5 as predicted by the EU RA from soil characteristics. We conclude that the EU RA is protective of Ni toxicity to higher-tier ecological endpoints, including in mixture with Cu, before the assessment factor of 2 is applied. We suggest that for prospective risk assessment, the bioavailability based PNEC (HC 5 /2) be used as a conservative screen, but for retrospective and site-specific risk assessment, the bioavailability based HC 5 is sufficient. - Highlights: • Higher-tier ecotoxicity thresholds calculated for field soils with elevated Ni. • Adjusted for Ni bioavailability using soil eCEC and species

  4. Validation of site-specific soil Ni toxicity thresholds with independent ecotoxicity and biogeochemistry data for elevated soil Ni.

    Science.gov (United States)

    Hale, Beverley; Gopalapillai, Yamini; Pellegrino, Amanda; Jennett, Tyson; Kikkert, Julie; Lau, Wilson; Schlekat, Christian; McLaughlin, Mike J

    2017-12-01

    The Existing Substances Regulation Risk Assessments by the European Union (EU RA) generated new toxicity data for soil organisms exposed to Ni added to sixteen field-collected soils with low background concentration of metals and varying physico-chemical soil characteristics. Using only effective cation exchange capacity (eCEC) as a bioavailability correction, chronic toxicity of Ni in soils with a wide range of characteristics could be predicted within a factor of two. The objective of the present study was to determine whether this was also the case for three independent data sets of Ni toxicity thresholds. Two of the data sets were from Community Based Risk Assessments in Port Colborne ON, and Sudbury ON (Canada) for soils containing elevated concentrations of Ni, Co and Cu arising from many decades of Ni mining, smelting and refining. The third data set was the Metals in Asia study of soluble Ni added to field soils in China. These data yielded 72 leached and aged EC 10 /NOEC values for soil Ni, for arthropods, higher plants and woodlot structure and function. These were reduced to nine most sensitive single or geometric mean species/function endpoints, none of which were lower than the HC 5 predicted for a soil with an eCEC of 20 cmol/kg. Most of these leached and aged EC 10 /NOEC values were from soils co-contaminated with Cu, in some cases at its median HC 5 as predicted by the EU RA from soil characteristics. We conclude that the EU RA is protective of Ni toxicity to higher-tier ecological endpoints, including in mixture with Cu, before the assessment factor of 2 is applied. We suggest that for prospective risk assessment, the bioavailability based PNEC (HC 5 /2) be used as a conservative screen, but for retrospective and site-specific risk assessment, the bioavailability based HC 5 is sufficient. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Synthesis, spectral, antitumor, antioxidant and antimicrobial studies on Cu(II), Ni(II) and Co(II) complexes of 4-[(1H-Benzoimidazol-2-ylimino)-methyl]-benzene-1,3-diol.

    Science.gov (United States)

    El-wakiel, Nadia; El-keiy, Mai; Gaber, Mohamed

    2015-08-05

    A new Schiff base of 2-aminobenzimidazole with 2,4-dihydroybezaldehyde (H₃L), and its Cu(II), Ni(II) and Co(II) complexes have been synthesized and characterized by elemental analyses, molar conductance, thermal analysis (TGA), inductive coupled plasma (ICP), magnetic moment measurements, IR, EI-mass, UV-Vis. and ESR spectral studies. On the basis of spectral studies and analytical data, it is evident that the Schiff base acts as dibasic tridentate ligand coordinating via deprotonated OH, NH and azomethine nitrogen atom. The results showed that Co(II) and Ni(II) complexes have tetrahedral structure while Cu(II) complexes has octahedral geometry. The kinetic and thermodynamic parameters of the thermal decomposition stages have been evaluated. The studied complexes were tested for their in vitro antimicrobial activities against some bacterial strains. The anticancer activity of the ligand and its metal complexes is evaluated against human liver Carcinoma (HEPG2) cell. These compounds exhibited a moderate and weak activity against the tested HEPG2 cell lines with IC₅₀ of 9.08, 18.2 and 19.7 μg/ml for ligand, Cu(II) and Ni(II) complexes, respectively. In vitro antioxidant activity of the newly synthesized compounds has also been evaluated. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Mercury release from deforested soils triggered by base cation enrichment

    International Nuclear Information System (INIS)

    Farella, N.; Lucotte, M.; Davidson, R.; Daigle, S.

    2006-01-01

    The Brazilian Amazon has experienced considerable colonization in the last few decades. Family agriculture based on slash-and-burn enables millions of people to live in that region. However, the poor nutrient content of most Amazonian soils requires cation-rich ashes from the burning of the vegetation biomass for cultivation to be successful, which leads to forest ecosystem degradation, soil erosion and mercury contamination. While recent studies have suggested that mercury present in soils was transferred towards rivers upon deforestation, little is known about the dynamics between agricultural land-use and mercury leaching. In this context, the present study proposes an explanation that illustrates how agricultural land-use triggers mercury loss from soils. This explanation lies in the competition between base cations and mercury in soils which are characterized by a low adsorption capacity. Since these soils are naturally very poor in base cations, the burning of the forest biomass suddenly brings high quantities of base cations to soils, destabilizing the previous equilibrium amongst cations. Base cation enrichment triggers mobility in soil cations, rapidly dislocating mercury atoms. This conclusion comes from principal component analyses illustrating that agricultural land-use was associated with base cation enrichment and mercury depletion. The overall conclusions highlight a pernicious cycle: while soil nutrient enrichment actually occurs through biomass burning, although on a temporary basis, there is a loss in Hg content, which is leached to rivers, entering the aquatic chain, and posing a potential health threat to local populations. Data presented here reflects three decades of deforestation activities, but little is known about the long-term impact of such a disequilibrium. These findings may have repercussions on our understanding of the complex dynamics of deforestation and agriculture worldwide

  7. Study of transition metal cations state on the catalyst surface by IR-spectroscopy of adsorbed test-molecules (CO, NO)

    International Nuclear Information System (INIS)

    Davydov, A.A.

    1993-01-01

    Using the methods of IR spectroscopy and ESR spectral manifestations of CO and NO in complexes with cations of vanadium in different oxidation degrees and coordination states have been studied. V 5+ cations do not coordinate NO and CO, but coordinate ammonia. Regular decrease of νCO values in V n+ -CO complexes with vanadium oxidation degree decrease has been shown. Spectral manifestation of NO complexes with V 4+ and V 3+ have been followed. The formation of V 4+ -NO, V 3+ -NO and V 3+ (NO) complexes has been established

  8. Partial exchange of the Li+, Na+ and K+ alkaline cations in the HNi(PO4).H2O layered compound

    International Nuclear Information System (INIS)

    Escobal, Jaione; Mesa, Jose; Pizarro, Jose; Bazan, Begona; Arriortua, Maria; Rojo, Teofilo

    2006-01-01

    The exchange of the Li + (1), Na + (2) and K + (3) alkaline cations in the layered HNi(PO 4 ).H 2 O was carried out starting from a methanolic solution containing the Li(OH).H 2 O hydroxide for (1) and the M(OH) (M=Na and K) hydroxides together with the (C 6 H 13 NH 2 ) 0.75 HNiPO 4 .H 2 O phases for (2) and (3). The compounds are stable until, approximately, 280 o C for (1) and 400 deg. C for phases (2) and (3), respectively. The IR spectra show the bands belonging to the water molecule and the (PO 4 ) 3- oxoanion. The diffuse reflectance spectra indicate the existence of Ni(II), d 8 , cations in slightly distorted octahedral geometry. The calculated Dq and Racah (B and C) parameters have a mean value of Dq=765, B=905 and C=3895cm -1 , respectively, in accordance with the values obtained habitually for this octahedral Ni(II) cation. The study of the exchange process performed by X-ray powder diffraction indicates that the exchange of the Li + cation in the lamellar HNi(PO 4 ).H 2 O phase is the minor rapid reaction, whereas the exchange of the Na + and K + cations needs the presence of the intermediate (C 6 H 13 NH 2 ) 0.75 HNiPO 4 .H 2 O intercalate in order to obtain the required product with the sodium and potassium ions. The Scanning electronic microscopy (SEM) images show a mean size of particle of 5μm. The Li + exchanged compound exhibits small ionic conductivity (Ωcm -1 is in the 10 -8 -10 -9 range) probably restrained by the methanol solvent. Magnetic measurements carried out from 5K to room temperature indicate antiferromagnetic coupling as the major interaction in the three phases. Notwithstanding the Li and K phases show a weak ferromagnetism at low temperatures

  9. Effect of Ni substitution on the structural and transport properties of Ni{sub x}Mn{sub 0.8-x}Mg{sub 0.2}Fe{sub 2}O{sub 4}; 0.0 {<=} x {<=} 0.40 ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.A., E-mail: moala1947@yahoo.com [Materials Science Lab (1), Physics Dept., Faculty of Science, Cairo Univ., Giza (Egypt); Bishay, Samiha T. [Phys. Dept., Faculty of Girls for Art, Science and Education, Ain Shams Univ., Cairo (Egypt); El-dek, S.I.; Omar, G. [Materials Science Lab (1), Physics Dept., Faculty of Science, Cairo Univ., Giza (Egypt)

    2011-01-21

    Research highlights: We aimed to merge the advantages of both Ni and Mn ferrites and to profit from the existence of Mg in small constant ratio to assure the large magnetization of the ferrite under investigation. To achieve such goals one have to investigate the effect of Ni substitution on the structural and electrical properties of Mn-Mg ferrite of the chemical formula Ni{sub x}Mn{sub 0.8-x}Mg{sub 0.2}Fe{sub 2}O{sub 4}; 0 {<=} x {<=} 0.40 prepared by conventional ceramic technique. - Abstract: Ni{sub x}Mn{sub 0.8-x}Mg{sub 0.2}Fe{sub 2}O{sub 4}; 0.0{<=} x {<=}0.40 was prepared by standard ceramic technique, presintering was carried out at 900 deg. C and final sintering at 1200 deg. C with heating/cooling rate 4 deg. C/min. X-ray diffraction analyses assured the formation of the samples in a single phase spinel cubic structure. The calculated crystal size was obtained in the range of 75-130 nm. A slight increase in the theoretical density and decrease in the porosity was obtained with increasing the nickel content. This result was discussed based on the difference in the atomic masses between Ni (58.71) and Mn (54.938). IR spectral analyses show four bands of the spinel ferrite for all the samples. The conductivity and dielectric loss factor give nearly continuous decrease with increasing Ni-content. This was discussed as the result of the significant role of the multivalent cations, such as iron, nickel, manganese, in the conduction mechanism. Anomalous behavior was obtained for the sample with x = 0.20 as highest dielectric constant, highest dielectric loss and highest conductivity. This anomalous behavior was explained due to the existence of two divalent cations on B-sites with the same ratio, namely, Mg{sup 2+} and Ni{sup 2+}.

  10. Investigating the pharmacodynamic and magnetic properties of pyrophosphate-bridged coordination complexes

    Science.gov (United States)

    Ikotun, Oluwatayo (Tayo) F.

    The multidentate nature of pyrophosphate makes it an attractive ligand for complexation of metal cations. The participation of pyrophosphate in a variety of biological pathways and its metal catalyzed hydrolysis has driven our investigation into its coordination chemistry. We have successfully synthesized a library of binuclear pyrophosphate bridge coordination complexes. The problem of pyrophosphate hydrolysis to phosphate in the presence of divalent metal ions was overcome by incorporating capping ligands such as 1,10-phenanthroline and 2,2'-bipyridine prior to the addition of the pyrophosphate. The magnetic properties of these complexes was investigated and magneto-structural analysis was conducted. The biological abundance of pyrophosphate and the success of metal based drugs such as cisplatin, prompted our investigation of the cytotoxic properties of M(II) pyrophosphate dimeric complexes (where M(II) is CoII, CuII, and NiII) in adriamycin resistant human ovarian cancer cells. Thess compounds were found to exhibit toxicity in the nanomolar to picomolar range. We conducted in vitro stability studies and the mechanism of cytoxicity was elucidated by performing DNA mobility and binding assays, enzyme inhibition assays, and in vitro oxidative stress studies.

  11. The Photoluminescent Properties of New Cationic Iridium(III Complexes Using Different Anions and Their Applications in White Light-Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Hui Yang

    2015-09-01

    Full Text Available Three cationic iridium(III complexes [Ir(ppy2(phen][PF6] (C1, [Ir(ppy2(phen]2SiF6 (C2 and [Ir(ppy2(phen]2TiF6 (C3 (ppy: 2-phenylpyridine, phen: 1, 10-phenanthroline using different anions were synthesized and characterized by 1H Nuclear magnetic resonance (1HNMR, mass spectra (MS, Fourier transform infrared (FTIR spectra and element analysis (EA. After the ultraviolet visible (UV-vis absorption spectra, photoluminescent (PL properties and thermal properties of the complexes were investigated, complex C1 and C3 with good optical properties and high thermal stability were used in white light-emitting diodes (WLEDs as luminescence conversion materials by incorporation with 460 nm-emitting blue GaN chips. The integrative performances of the WLEDs fabricated with complex C1 and C3 are better than those fabricated with the widely used yellow phosphor Y3Al5O12:Ce3+ (YAG. The color rendering indexes of the WLEDs with C1 and C3 are 82.0 and 82.6, the color temperatures of them are 5912 K and 3717 K, and the maximum power efficiencies of them are 10.61 Lm·W−1 and 11.41 Lm·W−1, respectively.

  12. The Photoluminescent Properties of New Cationic Iridium(III) Complexes Using Different Anions and Their Applications in White Light-Emitting Diodes.

    Science.gov (United States)

    Yang, Hui; Meng, Guoyun; Zhou, Yayun; Tang, Huaijun; Zhao, Jishou; Wang, Zhengliang

    2015-09-14

    Three cationic iridium(III) complexes [Ir(ppy)₂(phen)][PF₆] (C1), [Ir(ppy)₂(phen)]₂SiF₆ (C2) and [Ir(ppy)₂(phen)]₂TiF₆ (C3) (ppy: 2-phenylpyridine, phen: 1, 10-phenanthroline) using different anions were synthesized and characterized by ¹H Nuclear magnetic resonance (¹HNMR), mass spectra (MS), Fourier transform infrared (FTIR) spectra and element analysis (EA). After the ultraviolet visible (UV-vis) absorption spectra, photoluminescent (PL) properties and thermal properties of the complexes were investigated, complex C1 and C3 with good optical properties and high thermal stability were used in white light-emitting diodes (WLEDs) as luminescence conversion materials by incorporation with 460 nm-emitting blue GaN chips. The integrative performances of the WLEDs fabricated with complex C1 and C3 are better than those fabricated with the widely used yellow phosphor Y₃Al₅O 12 :Ce 3+ (YAG). The color rendering indexes of the WLEDs with C1 and C3 are 82.0 and 82.6, the color temperatures of them are 5912 K and 3717 K, and the maximum power efficiencies of them are 10.61 Lm·W -1 and 11.41 Lm·W -1 , respectively.

  13. Synthesis, crystal structure and magnetic properties of (acetato-κ²O,O')bis(5,5'-dimethyl-2,2'-bipyridine-κ²N,N')nickel(II) perchlorate monohydrate.

    Science.gov (United States)

    Farkašová, Nela; Černák, Juraj; Falvello, Larry R; Orendáč, Martin; Boča, Roman

    2015-04-01

    The title hydrated ionic complex, [Ni(CH3COO)(C12H12N2)2]ClO4·H2O or [Ni(ac)(5,5'-dmbpy)2]ClO4·H2O (where 5,5'-dmbpy is 5,5'-dimethyl-2,2'-bipyridine and ac is acetate), (1), was isolated as violet crystals from the aqueous ethanolic nickel acetate-5,5'-dmbpy-KClO4 system. Within the complex cation, the Ni(II) atom is hexacoordinated by two chelating 5,5'-dmbpy ligands and one chelating ac ligand. The mean Ni-N and Ni-O bond lengths are 2.0628 (17) and 2.1341 (15) Å, respectively. The water solvent molecule is disordered over two partially occupied positions and links two complex cations and two perchlorate anions into hydrogen-bonded centrosymmetric dimers, which are further connected by π-π interactions. The magnetic properties of (1) at low temperatures are governed by the action of single-ion anisotropy, D, which arises from the reduced local symmetry of the cis-NiO2N4 chromophore. The fitting of the variable-temperature magnetic data (2-300 K) gives g(iso) = 2.134 and D/hc = 3.13 cm(-1).

  14. Preparation, characterization, and efficient transfection of cationic liposomes and nanomagnetic cationic liposomes

    Directory of Open Access Journals (Sweden)

    Samadikhah HR

    2011-10-01

    Full Text Available Hamid Reza Samadikhah1,*, Asia Majidi2,*, Maryam Nikkhah2, Saman Hosseinkhani11Department of Biochemistry, 2Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran *These authors contributed equally to this work Purpose: Cationic liposomes (CLs are composed of phospholipid bilayers. One of the most important applications of these particles is in drug and gene delivery. However, using CLs to deliver therapeutic nucleic acids and drugs to target organs has some problems, including low transfection efficiency in vivo. The aim of this study was to develop novel CLs containing magnetite to overcome the deficiencies. Patients and methods: CLs and magnetic cationic liposomes (MCLs were prepared using the freeze-dried empty liposome method. Luciferase-harboring vectors (pGL3 were transferred into liposomes and the transfection efficiencies were determined by luciferase assay. Firefly luciferase is one of most popular reporter genes often used to measure the efficiency of gene transfer in vivo and in vitro. Different formulations of liposomes have been used for delivery of different kinds of gene reporters. Lipoplex (liposome–plasmid DNA complexes formation was monitored by gel retardation assay. Size and charge of lipoplexes were determined using particle size analysis. Chinese hamster ovary cells were transfected by lipoplexes (liposome-pGL3; transfection efficiency and gene expression level was evaluated by luciferase assay. Results: High transfection efficiency of plasmid by CLs and novel nanomagnetic CLs was achieved. Moreover, lipoplexes showed less cytotoxicity than polyethyleneimine and Lipofectamine™. Conclusion: Novel liposome compositions (1,2-dipalmitoyl-sn-glycero-3-phosphocholine [DPPC]/dioctadecyldimethylammonium bromide [DOAB] and DPPC/cholesterol/DOAB with high transfection efficiency can be useful in gene delivery in vitro. MCLs can also be used for targeted gene delivery, due to

  15. Complexation of the strontium cation with a macrocyclic lactam receptor: Experimental and theoretical study

    Czech Academy of Sciences Publication Activity Database

    Makrlík, E.; Záliš, Stanislav; Vaňura, P.

    2016-01-01

    Roč. 214, FEB 2016 (2016), s. 171-174 ISSN 0167-7322 Institutional support: RVO:61388955 Keywords : strontium cation * macrocyclic lactam receptor Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.648, year: 2016

  16. A uranium-based UO_2"+-Mn"2"+ single-chain magnet assembled trough cation-cation interactions

    International Nuclear Information System (INIS)

    Mougel, Victor; Chatelain, Lucile; Hermle, Johannes; Pecaut, Jacques; Mazzanti, Marinella; Caciuffo, Roberto; Colineau, Eric; Tuna, Floriana; Magnani, Nicola; Geyer, Arnaud de

    2014-01-01

    Single-chain magnets (SCMs) are materials composed of magnetically isolated one-dimensional (1D) units exhibiting slow relaxation of magnetization. The occurrence of SCM behavior requires the fulfillment of stringent conditions for exchange and anisotropy interactions. Herein, we report the synthesis, the structure, and the magnetic characterization of the first actinide-containing SCM. The 5f-3d heterometallic 1D chains [{[UO_2(salen)(py)][M(py)_4](NO_3)}]_n, (M=Cd (1) and M=Mn (2); py=pyridine) are assembled trough cation-cation interaction from the reaction of the uranyl(V) complex [UO_2(salen)py][Cp"*_2Co] (Cp"*=pentamethylcyclopentadienyl) with Cd(NO_3)_2 or Mn(NO_3)_2 in pyridine. The infinite UMn chain displays a high relaxation barrier of 134±0.8 K (93±0.5 cm"-"1), probably as a result of strong intra-chain magnetic interactions combined with the high Ising anisotropy of the uranyl(V) dioxo group. It also exhibits an open magnetic hysteresis loop at T<6 K, with an impressive coercive field of 3.4 T at 2 K.

  17. Electrostatically driven resonance energy transfer in "cationic" biocompatible indium phosphide quantum dots.

    Science.gov (United States)

    Devatha, Gayathri; Roy, Soumendu; Rao, Anish; Mallick, Abhik; Basu, Sudipta; Pillai, Pramod P

    2017-05-01

    Indium Phosphide Quantum Dots (InP QDs) have emerged as an alternative to toxic metal ion based QDs in nanobiotechnology. The ability to generate cationic surface charge, without compromising stability and biocompatibility, is essential in realizing the full potential of InP QDs in biological applications. We have addressed this challenge by developing a place exchange protocol for the preparation of cationic InP/ZnS QDs. The quaternary ammonium group provides the much required permanent positive charge and stability to InP/ZnS QDs in biofluids. The two important properties of QDs, namely bioimaging and light induced resonance energy transfer, are successfully demonstrated in cationic InP/ZnS QDs. The low cytotoxicity and stable photoluminescence of cationic InP/ZnS QDs inside cells make them ideal candidates as optical probes for cellular imaging. An efficient resonance energy transfer ( E ∼ 60%) is observed, under physiological conditions, between the cationic InP/ZnS QD donor and anionic dye acceptor. A large bimolecular quenching constant along with a linear Stern-Volmer plot confirms the formation of a strong ground state complex between the cationic InP/ZnS QDs and the anionic dye. Control experiments prove the role of electrostatic attraction in driving the light induced interactions, which can rightfully form the basis for future nano-bio studies between cationic InP/ZnS QDs and anionic biomolecules.

  18. Thermal, spectral, magnetic and biological studies of thiosemicarbazones complexes with metal ions: Cu(II), Co(II), Ni(II), Fe(III), Zn(II), Mn(II) and UO2(VI)

    International Nuclear Information System (INIS)

    Mashaly, M.M.; Seleem, H.S.; El-Behairy, M.A.; Habib, H.A.

    2004-01-01

    Thiosemicarbazones ligands, isatin-3-thiosemicarbazone(HIT) and N-acetylisatin-3-thiosemicarbazone (HAIT), which have tridentate ONN coordinating sites were prepared. The complexes of both ligands with Cu(II), Co(II), Ni(II), Fe(III), Zn(II), Mn(II) and UO 2 (VI) ions were isolated. The ligands and their metal complexes were characterized by elemental analysis, IR, UV-Vis and mass spectra, also by conductance, magnetic moment and TG-DSC measurements. All the transition metal complexes have octahedral configurations, except Cu-complexes which have planar geometry and the UO 2 (VI) complexes which have coordination number 8 and may acquire the distorted dodecahedral geometry. Thermal studies explored the possibility of obtaining new complexes. Inversion from octahedral to square-planar configuration occurred upon heating the parent Ni-HIAT complex to form the corresponding pyrolytic product. The antifungal activity against the tested organisms showed that some metal complexes enhanced the activity with respect to the parent ligands. (author)

  19. Cation disorder in shocked orthopyroxene.

    Science.gov (United States)

    Dundon, R. W.; Hafner, S. S.

    1971-01-01

    The study of cation distributions over nonequivalent lattice sites in minerals may reveal information on the history of temperature and pressure in rocks. Chemically homogeneous orthopyroxene specimens were shocked under well-controlled conditions in the laboratory in order to provide a basis for the interpretation of more complex natural materials. As a result of the investigation it is concluded that the distribution of magnesium and iron over the M1 and M2 positions in Bamle enstatite shocked at 1 megabar is highly disordered. It corresponds to an equilibrium distribution of at least 1000 C.

  20. Solvent extraction of Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Mn2+, Co2+ and Ni2+ into nitrobenzene using strontium dicarbol-lylcobaltate and tetra-tert-butyl p-tert-butylcalix[4]arene tetraacetate

    Directory of Open Access Journals (Sweden)

    E. MAKRLÍK

    2008-12-01

    Full Text Available The exchange extraction constants corresponding to the general equilibrium M2+(aq + SrL2+(nb D ML2+ (nb + Sr2+ (aq occurring in the two-phase water–nitrobenzene system (M2+ = Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Mn2+, Co2+ or Ni2+; L = tetra-tert-butyl p-tert-butylcalix[4]arene tetraacetate; aq = aqueous phase; nb = nitrobenzene phase were evaluated from extraction experiments and -activity measurements. Furthermore, the stability constants of the ML2+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order Ba2+ < Mn2+ < Pb2+, Co2+ < Cu2+, Zn2+ < Cd2+, Ni2+ < UO22+ < Ca2+.

  1. Rapid Two-Step Procedure for Large-Scale Purification of Pediocin-Like Bacteriocins and Other Cationic Antimicrobial Peptides from Complex Culture Medium

    OpenAIRE

    Uteng, Marianne; Hauge, Håvard Hildeng; Brondz, Ilia; Nissen-Meyer, Jon; Fimland, Gunnar

    2002-01-01

    A rapid and simple two-step procedure suitable for both small- and large-scale purification of pediocin-like bacteriocins and other cationic peptides has been developed. In the first step, the bacterial culture was applied directly on a cation-exchange column (1-ml cation exchanger per 100-ml cell culture). Bacteria and anionic compounds passed through the column, and cationic bacteriocins were subsequently eluted with 1 M NaCl. In the second step, the bacteriocin fraction was applied on a lo...

  2. Enrofloxacin sorption on smectite clays: effects of pH, cations, and humic acid.

    Science.gov (United States)

    Yan, Wei; Hu, Shan; Jing, Chuanyong

    2012-04-15

    Enrofloxacin (ENR) occurs widely in natural waters because of its extensive use as a veterinary chemotherapeutic agent. To improve our understanding of the interaction of this emerging contaminant with soils and sediments, sorption of ENR on homoionic smectites and kaolinite was studied as a function of pH, ionic strength, exchangeable cations, and humic acid concentration. Batch experiments and in situ ATR-FTIR analysis suggested multiple sorption mechanisms. Cation exchange was a major contributor to the sorption of cationic ENR species on smectite. The decreased ENR sorption with increasing ionic strength indicated the formation of outer-sphere complexes. Exchangeable cations significantly influenced the sorption capacity, and the observed order was Cscomplexes. The XRD analysis confirmed that interlayer intercalation is an important contributor to ENR sorption, while humic acid had a negligible contribution to the interlayer intercalation. The results of this study provide new insight into the molecular mechanisms of ENR sorption on clay minerals. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Vibrational spectroscopic investigation of some hofmann-T/sub d/ type complexes: Ni(I-phenyl piperazine)/sub 2/ M(CN)/sub 4/ (M = Cd or Hg)

    International Nuclear Information System (INIS)

    Parlak, C.; Senyel, M.

    2009-01-01

    New Hofmann-Td type complexes in the form of Ni(pp)/sub 2/M(CN)/sub 4/ (where pp = 1-Phenyl piperazine and M = Cd or Hg) have been prepared in powder form and their in/Tared (4000-100 cm-l) and Raman (2800-1650 cm/sup -1/) spectra have been reported. The results suggest that these compounds are similar in structure to the Hofmann- T d type complexes, in which the M atom is tetrahedrally coordinated to the carbon atoms of the four cyanide groups, while the Ni atom is octahedrally surrounded by six nitrogen atoms, two of which are from pp ligands which have been coordinated as a un identate ligand coordinating only through the NH nitrogen and the rest are from cyanide groups. In this host structure, the M(CN)/sub 4/ groups have been linked by the Ni(pp)z moieties to form a three-dimensional network. (author)

  4. The titanium tris-anilide cation [Ti(N[(t)Bu]Ar)3](+) stabilized as its perfluoro-tetra-phenylborate salt: structural characterization and synthesis in connection with redox activity of 4,4'-bipyridine dititanium complexes.

    Science.gov (United States)

    Spinney, Heather A; Clough, Christopher R; Cummins, Christopher C

    2015-04-21

    This work explores the reduction of 4,4'-bipyridine using two equivalents of the titanium(iii) complex Ti(N[(t)Bu]Ar)3 resulting in formation of a black, crystalline complex, (4,4'-bipy){Ti(N[(t)Bu]Ar)3}2, for which an X-ray structure determination is reported. The neutral, black, 4,4'-bipyridine-bridged bimetallic was found to be redox active, with mono- and di-anions being accessible electrochemically, and with the mono- and di-cations also being accessible chemically, and isolable, at least when using the weakly coordinating anion [B(C6F5)4](-) as the counter-ion. It proved possible to crystallize the salt [(4,4'-bipy){Ti(N[(t)Bu]Ar)3}2][B(C6F5)4]2 for a single-crystal X-ray structure investigation; in this instance it was revealed that the aromaticity of the 4,4'-bipyridine ligand, that had been disrupted upon reduction, had been regained. A rare cationic d(0) metal tris-amide complex, shown by X-ray crystallography to contain an intriguing pyramidal TiN3 core geometry, namely {Ti(N[(t)Bu]Ar)3}(+), could also be isolated when using [B(C6F5)4] as the essentially non-interacting counter-ion. This highly reactive cation should be considered as a potential intermediate in the plethora of reactions wherein Ti(N[(t)Bu]Ar)3 has been shown to effect the reduction of substrates including halogenated organic molecules, carbonyl compounds, organic nitriles, and metal complexes.

  5. Synthesis and studies on Cu(II), Co(II), Ni(II) complexes of Knoevenagel β-diketone ligands

    Science.gov (United States)

    Sumathi, S.; Tharmaraj, P.; Sheela, C. D.; Anitha, C.

    2012-11-01

    Transition metal complexes of various acetylacetone based ligands of the type ML [where M = Cu(II), Ni(II), Co(II); L = 3-(aryl)-pentane-2,4-dione] have been synthesized. The structural features have been derived from their elemental analysis, magnetic susceptibility, molar conductance, IR, UV-Vis, 1H NMR, Mass and ESR spectral studies. Conductivity measurements reveal that all the complexes are non-electrolytic in nature. Spectroscopic and other analytical data of the complexes suggest octahedral geometry for other metal(II) complexes. The redox behavior of the copper(II) complexes have been studied by cyclic voltammetry. The free ligands and their metal complexes have been screened for their in vitro biological activities against the bacteria Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus as well as the fungus Candida albicans by well diffusion method. The zone of inhibition value indicates that the most of the metal(II) complexes are found to possess increased activities compared to those of the free ligands. All synthesized compounds may serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG) efficiency of the ligands (L1-L3) was found to be considerable effect than that of urea and KDP (potassium dihydrogen phosphate).

  6. Use of a material conducting hydrogen cations

    International Nuclear Information System (INIS)

    Howe, A.T.; Shilton, M.G.

    1986-01-01

    The invention concerns a separator conducting hydrogenous for electrical devices, which contains at least one compound with the formula H(UO 2 )PO 4 x nH 2 O, H(UO 2 )AsO 4 x nH 2 O or H(UO 2 )IO 4 (OH) 2 x nH 2 O, where not more than 50% by weight of the H + is replaced by one or more cations, such as Li + , Na + , K + , NH 4 + , Cu 2+ , Mg 2+ , Ca 2+ , Ba 2+ , Sr 2+ , Pb 2+ , Fe 2+ , Co 2+ , Ni 2+ , Mn 2+ or Al 3+ . The electrical device having the separator can be an electrolysis cell, for example, an electro chromium cell. (H x WO 3 ), a hydrogen isotope enrichment device, a proton-sensitive electrode (eg for a pH meter), a battery or a fuel cell. (orig./MM) [de

  7. Synthesis, dielectric, conductivity and magnetic studies of LiNi1/3Co1/3Mn(1/3−xAlxO2 (x = 0.0, 0.02, 0.04 and 0.06 for cathode materials of lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    N. Murali

    Full Text Available Layered structure cathode materials LiNi1/3Co1/3Mn(1/3−xAlxO2 (x = 0.0, 0.02, 0.04 and 0.06 are prepared by the sol-gel method by adding citric acid as chelating agent. The physical, electrical and magnetic properties of the synthesized materials are systematically discussed using the structural (XRD, FESEM with EDS and FT-IR, impedance (LCR and electron spin resonance (ESR measurements. The X-ray diffraction pattern of the synthesized samples possessed the α-NaFeO2 structure of the space group, R3¯m, with no evidence of any impurities. The peak intensity ratio I(104/I(003 increased with Al concentration, which indicated the cation mixing between transition metal layer and lithium layer. The field effect scanning electron microscopy showed the particle size distribution in the range of 230–250 nm and EDS has been analysed for elemental mapping. The local structure is investigated by vibrational spectroscopy in FT-IR study. The impedance studies are characterized by complex impedance spectroscopy (CIS in the frequency range from 42 Hz to 1 MHz at room temperature (30 °C. The dielectric properties are analyzed in the framework of complex dielectric permittivity and formalism of the complex electric modulus. For these samples, the ESR analysis of magnetic measurements, the degree of cation mixing, is estimated to be Ni2+(3b = 2.75%. Keywords: Layered structure, XRD, FESEM, FT-IR, Dielectric, ESR

  8. Colchiceine Complexes with Lithium, Sodium and Potassium Salts − Spectroscopic Studies

    Directory of Open Access Journals (Sweden)

    Joanna Kurek

    2016-09-01

    Full Text Available Colchiceine complexes with Li+, Na+ and K+ cations have been synthesized and studied by 1H and 13C NMR, FT-IR, FAB MS and UV-Vis. It has been shown that colchiceine forms stable complexes especially with lithium cation and the most stable structures of the complexes are those in which the acetamide groups are involved in the coordination process. The structures of the colchiceine complexes with Li+, Na+ and K+ cations are discussed in details. This work is licensed under a Creative Commons Attribution 4.0 International License.

  9. Coupled Electronic and Magnetic Phase Transition in the Infinite-Layer Phase LaSrNiRuO4.

    Science.gov (United States)

    Patino, Midori Amano; Zeng, Dihao; Bower, Ryan; McGrady, John E; Hayward, Michael A

    2016-09-06

    Topochemical reduction of the ordered double perovskite LaSrNiRuO6 with CaH2 yields LaSrNiRuO4, an extended oxide phase containing infinite sheets of apex-linked, square-planar Ni(1+)O4 and Ru(2+)O4 units ordered in a checkerboard arrangement. At room temperature the localized Ni(1+) (d(9), S = (1)/2) and Ru(2+) (d(6), S = 1) centers behave paramagnetically. However, on cooling below 250 K the system undergoes a cooperative phase transition in which the nickel spins align ferromagnetically, while the ruthenium cations appear to undergo a change in spin configuration to a diamagnetic spin state. Features of the low-temperature crystal structure suggest a symmetry lowering Jahn-Teller distortion could be responsible for the observed diamagnetism of the ruthenium centers.

  10. An Integrated approach (thermodynamic, structural, and computational) to the study of complexation of alkali-metal cations by a lower-rim calix[4]arene amide derivative in acetonitrile.

    Science.gov (United States)

    Horvat, Gordan; Stilinović, Vladimir; Hrenar, Tomica; Kaitner, Branko; Frkanec, Leo; Tomišić, Vladislav

    2012-06-04

    The calix[4]arene secondary-amide derivative L was synthesized, and its complexation with alkali-metal cations in acetonitrile (MeCN) was studied by means of spectrophotometric, NMR, conductometric, and microcalorimetric titrations at 25 °C. The stability constants of the 1:1 (metal/ligand) complexes determined by different methods were in excellent agreement. For the complexation of M(+) (M = Li, Na, K) with L, both enthalpic and entropic contributions were favorable, with their values and mutual relations being quite strongly dependent on the cation. The enthalpic and overall stability was the largest in the case of the sodium complex. Molecular and crystal structures of free L, its methanol and MeCN solvates, the sodium complex, and its MeCN solvate were determined by single-crystal X-ray diffraction. The inclusion of a MeCN molecule in the calixarene hydrophobic cavity was observed both in solution and in the solid state. This specific interaction was found to be stronger in the case of metal complexes compared to the free ligand because of the better preorganization of the hydrophobic cone to accept the solvent molecule. Density functional theory calculations showed that the flattened cone conformation (C(2) point group) of L was generally more favorable than the square cone conformation (C(4) point group). In the complex with Na(+), L was in square cone conformation, whereas in its adduct with MeCN, the conformation was slightly distorted from the full symmetry. These conformations were in agreement with those observed in the solid state. The classical molecular dynamics simulations indicated that the MeCN molecule enters the L hydrophobic cavity of both the free ligand and its alkali-metal complexes. The inclusion of MeCN in the cone of free L was accompanied by the conformational change from C(2) to C(4) symmetry. As in solution studies, in the case of ML(+) complexes, an allosteric effect was observed: the ligand was already in the appropriate square cone

  11. Incremental binding free energies of aluminum (III) vs. magnesium (II) complexes

    International Nuclear Information System (INIS)

    Mercero, Jose M.; Mujika, Jon I.; Matxain, Jon M.; Lopez, Xabier; Ugalde, Jesus M.

    2003-01-01

    A sequential ligand addition to the aluminum (III) cation has been studied using the B3LYP functional and a combined all-electron/pseudopotentials basis set. The aluminum complexes are compared with analogous magnesium (II) complexes. Different thermodynamical data, such as incremental binding energies, enthalpies, entropies and free energies, are presented for these addition reactions. While the magnesium (II) cation can only accommodate three negatively charged ligands, aluminum (III) accommodates four even after including bulk solvent effects. The main differences between both cations complexing with the neutral ligands, is that aluminum (III) is not able to form complexes with methanol until the number of methanol ligands is equal to 3. Magnesium (II) prefers to bind methanol and formamide when the number of ligands is small, while aluminum prefers formamide. For the largest complexes both cations prefer to bind water

  12. Competitive/co-operative interactions in acid base sandwich: role of cation vs. substituents.

    Science.gov (United States)

    Kalpana, Ayyavoo; Akilandeswari, Lakshminarayanan

    2017-11-15

    The cation-π interaction can be envisaged as a lewis acid base interaction, and it is in line with Pearson's acid base concept. The critical examination of interactions between the π-acids (alkali metal cations - Li + , Na + and alkaline earth metal cations Mg 2+ , Ca 2+ ) on one face and tripodal Cr(CO) 3 moiety on the other π face of substituted arenes demonstrates the role of cation and substitutents in manipulating the interactions between them. The interaction of the two π acids on both faces of arene is not expectedly additive, rather it shows either depreciation of interaction energy revealing the competition of acids toward the base or enhancement of interaction energy denoting a cooperative effect. Among the metal cations under study, Mg 2+ shows a cooperative gesture. Although the substituents play a meek role, they unfailingly exert their electronic effects and are amply documented by excellent correlation of various parameters with the Hammett constant σ m . The elusive switching of λ max from the UV to IR region on binding Mg 2+ with substituted arene-Cr(CO) 3 complex is a characteristic clue that TDDFT can help design the ionic sensors for Mg 2+ cations.

  13. Synthesis and complexation properties towards uranyl cation of carboxylic acid derivatives of p-tert-butyl-calix[6]arene

    International Nuclear Information System (INIS)

    Souane, R.

    2005-03-01

    In the fuel reprocessing plants radioactive metals, and more particularly, uranium in UO 2 2+ form in the various installations, have many varied physico-chemical forms and there is a risk of exposure and internal contamination in the nuclear industry. It is necessary to exert a medical control to ensure the protection of the health of the workers. This medical control is done by dosing uranyl cation in the urine of the exposed people. This work forms part of this context. Indeed, we prepared a ligand able to complex the ion uranyl and which is also to be grafted on a solid support. In the family of calixarenes, the calix[6]arenes functionalized by three or four carboxylic functions were selected like chelating molecules of the ion uranyl. The properties of complexation of these calixarenes were studied by potentiometry in methanol, under these conditions balances of protonation and complexation were determined and the constant partners were obtained using the Hyperquad program. We synthesized tri-carboxylic calix[6]arenes comprising of the groupings nitro (NO 2 ) in para position of phenol in order to see the influence of a substitution in para position on the complexation. We also synthesized calix[6]arenes tetra-carboxylic in order to show the role of an additional carboxylic acid grouping. The potentiometric study determined thermodynamic parameters of protonation and complexation of carboxylic calix[6]arenes. The results of the complexation highlighted which complex UO 2 L corresponding to the ligand para-tert-butyl-calix[6]arene tetra-acid is more stable than that corresponding to the ligand mono-nitro calix[6]arene tri-acid (ΔlogΒ110 = 4.3), and than the effect of the groupings nitro in para position has low influence on the complexation of UO 2 2+ . This makes it possible to consider as possible the grafting of the calix[6]arenes which one knows the behaviour of trapping. To this end we synthesized the ligand 23. (author)

  14. Cation binding to 15-TBA quadruplex DNA is a multiple-pathway cation-dependent process

    Science.gov (United States)

    Reshetnikov, Roman V.; Sponer, Jiri; Rassokhina, Olga I.; Kopylov, Alexei M.; Tsvetkov, Philipp O.; Makarov, Alexander A.; Golovin, Andrey V.

    2011-01-01

    A combination of explicit solvent molecular dynamics simulation (30 simulations reaching 4 µs in total), hybrid quantum mechanics/molecular mechanics approach and isothermal titration calorimetry was used to investigate the atomistic picture of ion binding to 15-mer thrombin-binding quadruplex DNA (G-DNA) aptamer. Binding of ions to G-DNA is complex multiple pathway process, which is strongly affected by the type of the cation. The individual ion-binding events are substantially modulated by the connecting loops of the aptamer, which play several roles. They stabilize the molecule during time periods when the bound ions are not present, they modulate the route of the ion into the stem and they also stabilize the internal ions by closing the gates through which the ions enter the quadruplex. Using our extensive simulations, we for the first time observed full spontaneous exchange of internal cation between quadruplex molecule and bulk solvent at atomistic resolution. The simulation suggests that expulsion of the internally bound ion is correlated with initial binding of the incoming ion. The incoming ion then readily replaces the bound ion while minimizing any destabilization of the solute molecule during the exchange. PMID:21893589

  15. Synthesis of some (eta-arene)dihydridorhenium cations and their reactions with LiAlH/sub 4/ and LiAlD/sub 4/

    Energy Technology Data Exchange (ETDEWEB)

    Baudrey, D.; Boydell, P.; Ephritikhine, M.

    1986-03-01

    A series of cations (Re(eta-arene)H/sub 2/(PPh/sub 3/)/sub 2/)/sup +/ (arene benzene, toluene, p-xylene, or mesitylene) was prepared from the corresponding neutral dihydridocyclohexadienyl complexes by treatment with CPh/sub 3/BF/sub 4/. These cations reacted with LiAlH/sub 4/ and LiAlD/sub 4/ to form dihydridocyclohexadienyl complexes. The unusual selectivity of the hydride attack is explained by steric interactions between the ring methyl groups and the bulky phosphine ligands. The initial product of the reaction of the eta-mesitylene cation with LiAlD/sub 4/ allows the isomerisation mechanism for the cyclohexadienyl complexes to be clarified.

  16. Impact of cationic surfactant on the self-assembly of sodium caseinate.

    Science.gov (United States)

    Vinceković, Marko; Curlin, Marija; Jurašin, Darija

    2014-08-27

    The impact of a cationic surfactant, dodecylammonium chloride (DDACl), on the self-assembly of sodium caseinate (SC) has been investigated by light scattering, zeta potential, and rheological measurements as well as by microscopy (transmission electron and confocal laser scanning microscopy). In SC dilute solutions concentration-dependent self-assembly proceeds through the formation of spherical associates and their aggregation into elongated structures composed of connected spheres. DDACl interacts with SC via its hydrophilic and hydrophobic groups, inducing changes in SC self-assembled structures. These changes strongly depend on the surfactant aggregation states (monomeric or micellar) as well as concentration ratio of both components, leading to the formation of soluble and insoluble complexes of nano- to microdimensions. DDACl monomers interact with SC self-assembled entities in a different way compared to their micelles. Surfactant monomers form soluble complexes (similar to surfactant mixed micelles) at lower SC concentration but insoluble gelatinous complexes at higher SC concentration. At surfactant micellar concentration soluble complexes with casein chains wrapped around surfactant micelles are formed. This study suggests that the use of proper cationic surfactant concentration will allow modification and control of structural changes of SC self-assembled entities.

  17. Cationic rare-earth metal SALEN complexes.

    Science.gov (United States)

    Liu, Qiancai; Meermann, Christian; Görlitzer, Hans W; Runte, Oliver; Herdtweck, Eberhardt; Sirsch, Peter; Törnroos, Karl W; Anwander, Reiner

    2008-11-28

    Complexes (Salpren(tBu,tBu))Y[N(SiHMe2)2](thf) and (SALEN(tBu,tBu))La[N(SiHMe2)2](thf) (SALEN(tBu,tBu) = Salcyc(tBu,tBu) and Salpren(tBu,tBu)) were prepared from Ln[N(SiHMe2)2]3(thf)2 and H2SALEN(tBu,tBu). The yttrium complex was characterized by X-ray crystallography revealing intrinsic solid-state structural features: the metal centre is displaced by 1.05 angstroms from the [N2O2] least squares plane of a highly bent Salpren(tBu,tBu) ligand (angle(Ph,Ph) dihedral angle of 80.4(1) degrees ) and is coordinated asymmetrically by the silylamide ligand exhibiting one significant Y---(HSi) beta-agostic interaction (Y-N1-Si1, 106.90(9) degrees; Y---Si1, 3.2317(6) angstroms). Complexes (SALEN(tBu,tBu))Ln[N(SiHMe2)2](thf)n (n = 1, Sc; n = 2, Y, La) react with ammonium tetraphenylborate to form the ion pairs [(SALEN(tBu,tBu))Ln(thf)n][BPh4]. The cationisation was proven by X-ray crystal structure analyses of [(Salpren(tBu,tBu))Sc(thf)2][B(C6H5)4].2(thf) and [(Salpren(tBu,tBu))Ln(thf)3][B(C6H5)4].4(thf) (Ln = Y, La), showing an octahedral and pentagonal-bipyramidal coordination geometry, respectively.

  18. Acidity of cations and the solubility of oxides in the eutectic KCl-LiCl melt at 700 Deg C

    International Nuclear Information System (INIS)

    Cherginets, V.L.; Rebrova, T.P.

    1999-01-01

    Products of MgO, NiO and CoO solubility in KCl-LiCl melt at 700 Deg C were determined by the method of potentiometric titration using Pt(O 2 )IZrO 2 (Y 2 O 3 ) membrane oxygen electrode. It was ascertained that acid properties of Cd 2+ and Pb'2 + cations are levelled to Li + properties, a break in E-pO graduation dependence in KCl-LiCl melt was observed at pO ∼ 2. Increase in oxides solubility in the melt studied compared with KCl-NaCl and CsCl-KCl-NaCl melts stems from the presence of Li + cations in the melt studied, which possess stronger acid properties than those of Na + or K + [ru

  19. Carbon monoxide adsorption on low-silica zeolites: from single to dual and to multiple cation sites.

    Science.gov (United States)

    Otero Areán, C; Rodríguez Delgado, M; López Bauçà, C; Vrbka, L; Nachtigall, P

    2007-09-07

    Infrared spectra of CO adsorbed on the Al-rich Na-A zeolite were analysed by using a combined theoretical and experimental approach, showing that such spectra cannot be interpreted by assigning each IR band to CO interacting with a specific type of single cation site. This concept, which usually works well for high-silica zeolites, should not be uncritically extended to Al-rich zeolites that are crowded with cations in configurations which lead to preferential formation of CO adsorption complexes involving more than one cation site.

  20. Experimental studies and modelling of cation interactions with solid materials: application to the MIMICC project. (Multidimensional Instrumented Module for Investigations on chemistry-transport Coupled Codes)

    International Nuclear Information System (INIS)

    Hardin, Emmanuelle

    1999-01-01

    The study of cation interactions with solid materials is useful in order to define the chemistry interaction component of the MIMICC project (Multidimensional Instrumented Module for Investigations on chemistry-transport Coupled Codes). This project will validate the chemistry-transport coupled codes. Database have to be supplied on the cesium or ytterbium interactions with solid materials in suspension. The solid materials are: a strong cation exchange resin, a natural sand which presents small impurities, and a zirconium phosphate. The cation exchange resin is useful to check that the surface complexation theory can be applied on a pure cation exchanger. The sand is a natural material, and its isotherms will be interpreted using pure oxide-cation system data, such as pure silica-cation data. Then the study on the zirconium phosphate salt is interesting because of the increasing complexity in the processes (dissolution, sorption and co-precipitation). These data will enable to approach natural systems, constituted by several complex solids which can interfere on each other. These data can also be used for chemistry-transport coupled codes. Potentiometric titration, sorption isotherms, sorption kinetics, cation surface saturation curves are made, in order to obtain the different parameters relevant to the cation sorption at the solid surface, for each solid-electrolyte-cation system. The influence of different parameters such as ionic strength, pH, and electrolyte is estimated. All the experimental curves are fitted with FITEQL code based on the surface complexation theory using the constant capacitance model, in order to give a mechanistic interpretation of the ion retention phenomenon at the solid surface. The speciation curves of all systems are plotted, using the FITEQL code too. Systems with an increasing complexity are studied: dissolution, sorption and coprecipitation coexist in the cation-salt systems. Then the data obtained on each single solid, considered

  1. Synthesis, Crystal Structures, Magnetic Properties, and Theoretical Investigation of a New Series of NiII-LnIII-WV Heterotrimetallics: Understanding the SMM Behavior of Mixed Polynuclear Complexes.

    Science.gov (United States)

    Vieru, Veacheslav; Pasatoiu, Traian D; Ungur, Liviu; Suturina, Elizaveta; Madalan, Augustin M; Duhayon, Carine; Sutter, Jean-Pascal; Andruh, Marius; Chibotaru, Liviu F

    2016-12-05

    The polynuclear compounds containing anisotropic metal ions often exhibit efficient barriers for blocking of magnetization at fairly arbitrary geometries. However, at variance with mononuclear complexes, which usually become single-molecule magnets (SMM) under the sole requirement of a highly axial crystal field at the metal ion, the factors influencing the SMM behavior in polynuclear complexes, especially, with weakly axial magnetic ions, still remain largely unrevealed. As an attempt to clarify these conditions, we present here the synthesis, crystal structures, magnetic behavior, and ab initio calculations for a new series of Ni II -Ln III -W V trimetallics, [(CN) 7 W(CN)Ni(H 2 O)(valpn)Ln(H 2 O) 4 ]·H 2 O (Ln = Y 1, Eu 2, Gd 3, Tb 4, Dy 5, Lu 6). The surprising finding is the absence of the magnetic blockage even for compounds involving strongly anisotropic Dy III and Tb III metal ions. This is well explained by ab initio calculations showing relatively large transversal components of the g-tensor in the ground exchange Kramers doublets of 1 and 4 and large intrinsic tunneling gaps in the ground exchange doublets of 3 and 5. In order to get more insight into this behavior, another series of earlier reported compounds with the same trinuclear [W V Ni II Ln III ] core structure, [(CN) 7 W(CN)Ni(dmf)(valdmpn)Ln(dmf) 4 ]·H 2 O (Ln = Gd III 7, Tb III 8a, Dy III 9, Ho III 10), [(CN) 7 W(CN)Ni(H 2 O)(valdmpn)Tb(dmf) 2.5 (H 2 O) 1.5 ]·H 2 O·0.5dmf 8b, and [(CN) 7 W(CN)Ni(H 2 O)(valdmpn)Er(dmf) 3 (H 2 O) 1 ]·H 2 O·0.5dmf 11, has been also investigated theoretically. In this series, only 8b exhibits SMM behavior which is confirmed by the present ab initio calculations. An important feature for the entire series is the strong ferromagnetic coupling between Ni(II) and W(V), which is due to an almost perfect trigonal dodecahedron geometry of the octacyano wolframate fragment. The reason why only 8b is an SMM is explained by positive zero-field splitting on the nickel

  2. Di-μ-cyanido-tetra­cyanido(5,5,7,12,12,14-hexa­methyl-1,4,8,11-tetra­aza­cyclo­tetra­decane)[N-(quinolin-8-yl)quinoline-2-carboxamidato]diiron(III)nickel(II) 2.07-hydrate

    Science.gov (United States)

    Yang, Yuqi; Zhou, Hongbo; Shen, Xiaoping

    2013-01-01

    The asymmetric unit of the title complex, [Fe2Ni(C19H12N3O)2(CN)6(C16H36N4)]·2.07H2O, contains one [Fe(qcq)(CN)3]− anion, half a [Ni(teta)]2+ cation and two partially occupied inter­stitial water mol­ecules [qcq− is the N-(quinolin-8-yl)quinoline-2-carboxamidate anion and teta is 5,5,7,12,12,14-hexa­methyl-1,4,8,11-tetra­aza­cyclo­tetra­deca­ne]. In the complex mol­ecule, two [Fe(qcq)(CN)3]− anions additionally coordinate the central [Ni(teta)]2+ cation through cyanide groups in a trans mode, resulting in a trinuclear structure with the Ni2+ cation lying on an inversion centre. The two inter­stitial water mol­ecules are partially occupied, with occupancy factors of 0.528 (10) and 0.506 (9). O—H⋯O and O—H⋯N hydrogen bonding involving the two lattice water molecules and the carbonyl function and a teta N atom in an adjacent cluster leads to the formation of layers extending parallel to (010). PMID:23723777

  3. The adsorption of helium atoms on coronene cations

    Energy Technology Data Exchange (ETDEWEB)

    Kurzthaler, Thomas; Rasul, Bilal; Kuhn, Martin; Scheier, Paul, E-mail: Paul.Scheier@uibk.ac.at, E-mail: andrew.ellis@le.ac.uk [Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck (Austria); Lindinger, Albrecht [Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin (Germany); Ellis, Andrew M., E-mail: Paul.Scheier@uibk.ac.at, E-mail: andrew.ellis@le.ac.uk [Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)

    2016-08-14

    We report the first experimental study of the attachment of multiple foreign atoms to a cationic polycyclic aromatic hydrocarbon (PAH). The chosen PAH was coronene, C{sub 24}H{sub 12}, which was added to liquid helium nanodroplets and then subjected to electron bombardment. Using mass spectrometry, coronene cations decorated with helium atoms were clearly seen and the spectrum shows peaks with anomalously high intensities (“magic number” peaks), which represent ion-helium complexes with added stability. The data suggest the formation of a rigid helium layer consisting of 38 helium atoms that completely cover both faces of the coronene ion. Additional magic numbers can be seen for the further addition of 3 and 6 helium atoms, which are thought to attach to the edge of the coronene. The observation of magic numbers for the addition of 38 and 44 helium atoms is in good agreement with a recent path integral Monte Carlo prediction for helium atoms on neutral coronene. An understanding of how atoms and molecules attach to PAH ions is important for a number of reasons including the potential role such complexes might play in the chemistry of the interstellar medium.

  4. Reactivity of monoolefin ligand in transition metal complexes

    International Nuclear Information System (INIS)

    Rybinskaya, M.I.

    1978-01-01

    The main tendencies in the coordinated olefin ligand property changes are discussed in the transition metal complexes in comparison with free olefins. The review includes the papers published from 1951 up to 1976. It has been shown that in complexes with transition metal cations olefin π-base acquires the ability to react with nucleophylic reagents. Olefin π-acids in complexes with zero valent metals are easily subjected to electrophylic reagent action. At coordination with transition metal cations the olefin properties are generally preserved, while in the zero-valent metal complexes the nonsaturated ligand acquires the properties of a saturated compounds. The ability of transition metal cations in complexes to intensify reactions of nucleophylic bimolecular substitution of vinyl halogen is clearly detected in contrast to the zero valent metal complexes. It has been shown that investigations of the coordinated olefin ligand reactivity give large possibilities in the further development of the organic synthesis. Some reactions are taken as the basis of important industrial processes

  5. Synthesis, Characterization, and Biological Activity of Mn(II, Fe(II, Co(II, Ni(II, Cu(II, Zn(II, and Cd(II Complexes of N-Thiophenoyl-N′-Phenylthiocarbohydrazide

    Directory of Open Access Journals (Sweden)

    M. Yadav

    2013-01-01

    Full Text Available Mn(II, Fe(II, Co(II, Ni(II, Cu(II, Zn(II, and Cd(II complex of N-thiophenoyl -N′-phenylthiocarbohydrazide (H2 TPTH have been synthesized and characterized by elemental analysis, magnetic susceptibility measurements, infrared, NMR, electronic, and ESR spectral studies. The complexes were found to have compositions [Mn(H TPTH2], [Co(TPTH (H2O2], [Ni(TPTH (H2O2], [Cu(TPTH], [Zn(H TPTH], [Cd(H TPTH2], and [Fe(H TPTH2(EtOH]. The magnetic and electronic spectral studies suggest square planar geometry for [Cu(TPTH], tetrahedral geometry for [Zn(TPTH] and [Cd(H TPTH2], and octahedral geometry for rest of the complexes. The infrared spectral studies of the 1 : 1 deprotonated complexes suggest bonding through enolic oxygen, thiolato sulfur, and both the hydrazinic nitrogens. Thus, H2TPTH acts as a binegative tetradentate ligand. H2 TPTH and its metal complexes have been screened against several bacteria and fungi.

  6. The chemistry of separations ligand degradation by organic radical cations

    International Nuclear Information System (INIS)

    Mezyk, S.P.; Horne, G.P.; Mincher, B.J.; Zalupski, P.R.; Cook, A.R.; Wishart, J.F.

    2016-01-01

    Solvent based extractions of used nuclear fuel use designer ligands in an organic phase extracting ligand complexed metal ions from an acidic aqueous phase. These extractions will be performed in highly radioactive environments, and the radiation chemistry of all these complexing agents and their diluents will play a major role in determining extraction efficiency, separation factors, and solvent-recycle longevity. Although there has been considerable effort in investigating ligand damage occurring in acidic water radiolysis conditions, only minimal fundamental kinetic and mechanistic data has been reported for the degradation of extraction ligands in the organic phase. Extraction solvent phases typically use normal alkanes such as dodecane, TPH, and kerosene as diluents. The radiolysis of such diluents produce a mixture of radical cations (R"."+), carbon-centered radicals (R".), solvated electrons, and molecular products such as hydrogen. Typically, the radical species will preferentially react with the dissolved oxygen present to produce relatively inert peroxyl radicals. This isolates the alkane radical cation species, R"."+ as the major radiolytically-induced organic species that can react with, and degrade, extraction agents in this phase. Here we report on our recent studies of organic radical cation reactions with 2 ligands: CMPO and TODGA. Elucidating these parameters, and combining them with the known acidic aqueous phase chemistry, will allow a full, fundamental, understanding of the impact of radiation on solvent extraction based separation processes to be achieved. (authors)

  7. Structure relationship of cationic lipids on gene transfection mediated by cationic liposomes.

    Science.gov (United States)

    Paecharoenchai, Orapan; Niyomtham, Nattisa; Apirakaramwong, Auayporn; Ngawhirunpat, Tanasait; Rojanarata, Theerasak; Yingyongnarongkul, Boon-ek; Opanasopit, Praneet

    2012-12-01

    The aim of this study was to investigate the transfection efficiency of cationic liposomes formulated with phosphatidylcholine (PC) and novel synthesized diethanolamine-based cationic lipids at a molar ratio of 5:1 in comparison with Lipofectamine™ 2000. Factors affecting transfection efficiency and cell viability, including the chemical structure of the cationic lipids, such as different amine head group (diamine and polyamine; and non-spermine and spermine) and acyl chain lengths (C14, C16, and C18) and the weight ratio of liposomes to DNA were evaluated on a human cervical carcinoma cell line (HeLa cells) using the pDNA encoding green fluorescent protein (pEGFP-C2). Characterizations of these lipoplexes in terms of size and charge measurement and agarose gel electrophoresis were performed. The results from this study revealed that almost no transfection was observed in the liposome formulations composed of cationic lipids with a non-spermine head group. In addition, the transfection efficiency of these cationic liposomes was in the following order: spermine-C14 > spermine-C16 > spermine-C18. The highest transfection efficiency was observed in the formulation of spermine-C14 liposomes at a weight ratio of 25; furthermore, this formulation was safe for use in vitro. In conclusion, cationic liposomes containing spermine head groups demonstrated promising potential as gene carriers.

  8. Synthesis of cationic star polymers by simplified electrochemically mediated ATRP

    Directory of Open Access Journals (Sweden)

    P. Chmielarz

    2016-10-01

    Full Text Available Cyclodextrin-based cationic star polymers were synthesized using β-cyclodextrin (β-CD core, and 2-(dimethylamino ethyl methacrylate (DMAEMA as hydrophilic arms. Star-shaped polymers were prepared via a simplified electrochemically mediated ATRP (seATRP under potentiostatic and galvanostatic conditions. The polymerization results showed molecular weight (MW evolution close to theoretical values, and maintained narrow molecular weight distribution (MWD of obtained stars. The rate of the polymerizations was controlled by applying more positive potential values thereby suppressing star-star coupling reactions. Successful chain extension of the ω-functional arms with a hydrophobic n-butyl acrylate (BA formed star block copolymers and confirmed the living nature of the β-CD-PDMAEMA star polymers prepared by seATRP. Novelty of this work is that the β-CD-PDMAEMA-b-PBA cationic star block copolymers were synthesized for the first time via seATRP procedure, utilizing only 40 ppm of catalyst complex. The results from 1H NMR spectral studies support the formation of cationic star (copolymers.

  9. Interfacial Tryptophan Residues: A Role for the Cation-{pi} Effect?

    DEFF Research Database (Denmark)

    Petersen, Frederic Nicolas Rønne; Jensen, Morten Ø.; Helix Nielsen, Claus

    2005-01-01

    Integral membrane proteins are characterized by having a preference for aromatic residues, e.g., tryptophan (W), at the interface between the lipid bilayer core and the aqueous phase. The reason for this is not clear, but it seems that the preference is related to a complex interplay between steric...... between the nitrogen moiety of lipid molecule headgroups and the pi-electron distribution of gramicidin (gA) tryptophan residues (W(9), W(11), W(13), and W(15)) using molecular dynamics (MD) simulations of gA embedded in two hydrated lipid bilayers composed of 1-palmitoyl-2-oleoylphosphatidylethanolamine....... Our criteria for cation-pi interactions are based on distance and angular requirements, and the results from our model suggest that cation-pi interactions are relevant for W(PE)(11), W(PE)(13), W(PE)(15), and, to some extent, W(PC)(11) and W(PC)(13). In our model, W(9)does not seem to engage in cation...

  10. New insights into the coordination chemistry of Schiff bases derived from amino acids: Planar [Ni4] complexes with tyrosine side-chains

    Science.gov (United States)

    Muche, Simon; Hołyńska, Małgorzata

    2017-08-01

    Structure and properties of a rare metal complex of the chiral Schiff base ligand derived from ortho-vanillin and L-tyrosine are presented. This study is a continuation of research on ligands containing biologically compatible moieties. The ligand is also fully characterized in form of a sodium salt, in particular in solution, for the first time. The metal complex contains a unique bowl-shaped [Ni4] core. Its structure is investigated both in solution (ESI-MS, NMR) and in solid state (X-ray diffraction studies). Under certain conditions the complex can be isolated as crystalline DMF solvate which is studied in solid state.

  11. A new family of Ni4 and Ni6 aggregates from the self-assembly of [Ni2] building units: role of carboxylate and carbonate bridges.

    Science.gov (United States)

    Pait, Moumita; Bauzá, Antonio; Frontera, Antonio; Colacio, Enrique; Ray, Debashis

    2015-05-18

    Carboxylato (R = (t)Bu and Et) and carbonato bridges have been utilized for nickel(II)-based aggregates [Ni4(μ-H2L)2(μ3-OH)2(μ1,3-O2CBu(t))2](NO3)2·H2O·2DMF (1·H2O·2DMF), Ni4(μ-(hy)HL)2(μ3-OMe)2(μ1,1-N3)2(μ1,3-O2CEt)2]·4H2O (2·4H2O), and Ni6(μ4-L)(μ3-L)2(μ6-CO3)(H2O)8](ClO4)·9H2O (3·9H2O). Building blocks [Ni2(μ-H2L)](3+), [Ni2(μ-(hy)HL)](3+), and [Ni2(μ-L)](+) originating from [Ni2(μ-H2L)](3+) have been trapped in these complexes. The complexes have been characterized by X-ray crystallography, magnetic measurements, and density functional theory (DFT) analysis. In 1, the magnetic interactions are transmitted through the μ3-phenoxido/μ3-hydroxido/syn-syn-(t)BuCO2(-), μ3-phenoxido/μ3- hydroxido, and double μ3-phenoxido/double μ3-hydroxido bridges with J = +11.4 cm(-1), J1 = -2.1 cm(-1), and J2 = -2.8 cm(-1), respectively. In 2, the interactions are ferromagnetic, with J1 = +27.5 cm(-1), J2 = +20.62 cm(-1), and J3 = +1.52 cm(-1) describing the magnetic couplings through the μ-phenoxidoo/μ3-methoxido, μ-azido/μ3-methoxido, and μ3-methoxido/μ3-methoxido exchange pathways, respectively. Complex 3 gives J1 = -3.30 cm(-1), J2 = +1.7 cm(-1), and J3 = -12.8 cm(-1) for exchange pathways mediated by μ-phenoxido/μ-carbonato, μ-alkoxido/μ-alkooxido/μ-syn-syn-carbonato, and the μ-phenoxido/μ-carbonato, respectively. Interestingly, 1 and 3 below 20 K and 35 K, respectively, show an abrupt increase of the χMT product to reach a magnetic-field-dependent maximum, which is associated with a slightly frequency-dependent out-of-phase alternating-current peak. DFT calculations have also been performed on 1-3 to explain the exchange interaction mechanisms and to support the magnitude and sign of the magnetic coupling constants between the Ni(II) ions.

  12. Water-Gas Shift and CO Methanation Reactions over Ni-CeO2(111) Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    S Senanayake; J Evans; S Agnoli; L Barrio; T Chen; J Hrbek; J Rodriguez

    2011-12-31

    X-ray and ultraviolet photoelectron spectroscopies were used to study the interaction of Ni atoms with CeO{sub 2}(111) surfaces. Upon adsorption on CeO{sub 2}(111) at 300 K, nickel remains in a metallic state. Heating to elevated temperatures (500-800 K) leads to partial reduction of the ceria substrate with the formation of Ni{sup 2+} species that exists as NiO and/or Ce{sub 1-x}Ni{sub x}O{sub 2-y}. Interactions of nickel with the oxide substrate significantly reduce the density of occupied Ni 3d states near the Fermi level. The results of core-level photoemission and near-edge X-ray absorption fine structure point to weakly bound CO species on CeO{sub 2}(111) which are clearly distinguishable from the formation of chemisorbed carbonates. In the presence of Ni, a stronger interaction is observed with chemisorption of CO on the admetal. When the Ni is in contact with Ce{sup +3} cations, CO dissociates on the surface at 300 K forming NiC{sub x} compounds that may be involved in the formation of CH{sub 4} at higher temperatures. At medium and large Ni coverages (>0.3 ML), the Ni/CeO{sub 2}(111) surfaces are able to catalyze the production of methane from CO and H{sub 2}, with an activity slightly higher than that of Ni(100) or Ni(111). On the other hand, at small coverages of Ni (<0.3 ML), the Ni/CeO{sub 2}(111) surfaces exhibit a very low activity for CO methanation but are very good catalysts for the water-gas shift reaction.

  13. Mechanistic Implications for the Ni(I-Catalyzed Kumada Cross-Coupling Reaction

    Directory of Open Access Journals (Sweden)

    Linda Iffland

    2017-11-01

    Full Text Available Herein we report on the cross-coupling reaction of phenylmagnesium bromide with aryl halides using the well-defined tetrahedral Ni(I complex, [(TriphosNiICl] (Triphos = 1,1,1-tris(diphenylphosphinomethylethane. In the presence of 0.5 mol % [(TriphosNiICl], good to excellent yields (75–97% of the respective coupling products within a reaction time of only 2.5 h at room temperature were achieved. Likewise, the tripodal Ni(IIcomplexes [(κ2-TriphosNiIICl2] and [(κ3-TriphosNiIICl](X (X = ClO4, BF4 were tested as potential pre-catalysts for the Kumada cross-coupling reaction. While the Ni(II complexes also afford the coupling products in comparable yields, mechanistic investigations by UV/Vis and electron paramagnetic resonance (EPR spectroscopy indicate a Ni(I intermediate as the catalytically active species in the Kumada cross-coupling reaction. Based on experimental findings and density functional theory (DFT calculations, a plausible Ni(I-catalyzed reaction mechanism for the Kumada cross-coupling reaction is presented.

  14. Restructuring of a peat in interaction with multivalent cations: effect of cation type and aging time.

    Science.gov (United States)

    Kunhi Mouvenchery, Yamuna; Jaeger, Alexander; Aquino, Adelia J A; Tunega, Daniel; Diehl, Dörte; Bertmer, Marko; Schaumann, Gabriele Ellen

    2013-01-01

    It is assumed to be common knowledge that multivalent cations cross-link soil organic matter (SOM) molecules via cation bridges (CaB). The concept has not been explicitly demonstrated in solid SOM by targeted experiments, yet. Therefore, the requirements for and characteristics of CaB remain unidentified. In this study, a combined experimental and molecular modeling approach was adopted to investigate the interaction of cations on a peat OM from physicochemical perspective. Before treatment with salt solutions of Al(3+), Ca(2+) or Na(+), respectively, the original exchangeable cations were removed using cation exchange resin. Cation treatment was conducted at two different values of pH prior to adjusting pH to 4.1. Cation sorption is slower (>2 h) than deprotonation of functional groups (cation addition and decreased with increasing cation valency. Sorption coefficients were similar for all cations and at both pH. This contradicts the general expectations for electrostatic interactions, suggesting that not only the interaction chemistry but also spatial distribution of functional groups in OM determines binding of cations in this peat. The reaction of contact angle, matrix rigidity due to water molecule bridges (WaMB) and molecular mobility of water (NMR analysis) suggested that cross-linking via CaB has low relevance in this peat. This unexpected finding is probably due to the low cation exchange capacity, resulting in low abundance of charged functionalities. Molecular modeling demonstrates that large average distances between functionalities (∼3 nm in this peat) cannot be bridged by CaB-WaMB associations. However, aging strongly increased matrix rigidity, suggesting successive increase of WaMB size to connect functionalities and thus increasing degree of cross-linking by CaB-WaMB associations. Results thus demonstrated that the physicochemical structure of OM is decisive for CaB and aging-induced structural reorganisation can enhance cross-link formation.

  15. Thermochemical characteristics of La n+1Ni nO3n+1 oxides

    International Nuclear Information System (INIS)

    Bannikov, D.O.; Safronov, A.P.; Cherepanov, V.A.

    2006-01-01

    Lanthanum nickelates: La 2 NiO 4+δ , La 3 Ni 2 O 7-δ , La 4 Ni 3 O 10-δ and LaNiO 3-δ the members of Ruddlesden-Popper series La n+1 Ni n O 3n+1 were prepared using citrate route. Dissolution enthalpies of complex oxides as well as a number of subsidiary substances were measured by means of Calvet calorimeter in 1 M solution of hydrochloric acid at 25 deg. C. The dissolution scheme of complex oxides in hydrochloric acid was proposed and enthalpies of formation of the complex oxides from binary oxides were calculated considering oxygen nonstoichiometry of these substances. Enthalpies of step-by-step oxidation were evaluated. Partial enthalpy contribution of LaO layers was calculated endothermic equals to 30.9 J/mol while partial enthalpy contribution of perovskite LaNiO 3 layers was negative equals to -97.0 J/mol. Enthalpy of formation of any complex oxide of Ruddlesden-Popper series fits very well to the linear regression based on these values

  16. Effect of an in-plane ligand on the electronic structures of bromo-bridged nano-wire Ni-Pd mixed-metal complexes, [Ni(1-x)Pd(x)(bn)2Br]Br2 (bn = 2S,3S-diaminobutane).

    Science.gov (United States)

    Sasaki, Mari; Wu, Hashen; Kawakami, Daisuke; Takaishi, Shinya; Kajiwara, Takashi; Miyasaka, Hitoshi; Breedlove, Brian K; Yamashita, Masahiro; Kishida, Hideo; Matsuzaki, Hiroyuki; Okamoto, Hiroshi; Tanaka, Hisaaki; Kuroda, Shinichi

    2009-08-03

    Single crystals of quasi-one-dimensional bromo-bridged Ni-Pd mixed-metal complexes with 2S,3S-diaminobutane (bn) as an in-plane ligand, [Ni(1-x)Pd(x)(bn)(2)Br]Br(2), were obtained by using an electrochemical oxidation method involving mixed methanol/2-propanol (1:1) solutions containing different ratios of [Ni(II)(bn)(2)]Br(2) and [Pd(II)(bn)(2)]Br(2). To investigate the competition between the electron-correlation of the Ni(III) states, or Mott-Hubbard states (MH), and the electron-phonon interaction of the Pd(II)-Pd(IV) mixed valence states, or charge-density-wave states (CDW), in the Ni-Pd mixed-metal compounds, X-ray structure analyses, X-ray oscillation photograph, and Raman, IR, ESR, and single-crystal reflectance spectra were analyzed. In addition, the local electronic structures of Ni-Pd mixed-metal single crystals were directly investigated by using scanning tunneling microscopy (STM) at room temperature and ambient pressure. The oxidation states of [Ni(1-x)Pd(x)(bn)(2)Br]Br(2) changed from a M(II)-M(IV) mixed valence state to a M(III) MH state at a critical mixing ratio (x(c)) of approximately 0.8, which is lower than that of [Ni(1-x)Pd(x)(chxn)(2)Br]Br(2) (chxn = 1R,2R-diaminocyclohexane) (x(c) approximately 0.9) reported previously. The lower value of x(c) for [Ni(1-x)Pd(x)(bn)(2)Br]Br(2) can be explained by the difference in their CDW dimensionalities because the three-dimensional CDW ordering in [Pd(bn)(2)Br]Br(2) observed by using X-ray diffuse scattering stabilizes the Pd(II)-Pd(IV) mixed valence state more than two-dimensional CDW ordering in [Pd(chxn)(2)Br]Br(2) does, which has been reported previously.

  17. Optimization of cationic lipid mediated gene transfer: structure-function, physico-chemical, and cellular studies.

    Science.gov (United States)

    Carrière, Marie; Tranchant, Isabelle; Niore, Pierre-Antoine; Byk, Gerardo; Mignet, Nathalie; Escriou, Virginie; Scherman, Daniel; Herscovici, Jean

    2002-01-01

    The rationale design aimed at the enhancement of cationic lipid mediated gene transfer is discussed. These improvements are based on the straight evaluation of the structure-activity relationship and on the introduction of new structures. Much attention have been given to the supramolecular structures of the lipid/DNA complexes, to the effect of serum on gene transfer and to the intracellular trafficking of the lipoplexes. Finally new avenue using reducible cationic lipids has been discussed.

  18. Synthesis, spectroscopic, thermal and structural properties of [M(3-aminopyridine)2Ni(μ-CN)2(CN)2]n (M(II) = Co and Cu) heteropolynuclear cyano-bridged complexes

    Science.gov (United States)

    Kartal, Zeki

    2016-01-01

    Two novel cyano-bridged heteropolynuclear complexes, [Co(3-aminopyridine)2Ni(μ-CN)2(CN)2]n and [Cu(3-aminopyridine)2Ni(μ-CN)2(CN)2]n have been synthesized and characterized by elemental, thermal, FT-IR and FT-Raman spectroscopies. The structures of complexes have been determined by X-ray powder diffraction. The FT-IR and FT-Raman spectra of complexes have been recorded in the region of 3500-400 cm-1 and 3500-100 cm-1, respectively. General information was acquired about structural properties of these complexes from FT-IR and FT-Raman spectra by considering changes at characteristic peaks of the cyano group and 3AP. The splitting of the ν(Ctbnd N) stretching bands in the FT-IR spectra for complexes indicates the presence of terminal and bridging cyanides. The thermal behaviors of these complexes have been also investigated in the range of 25-950 °C using TG and DTG methods. Magnetic susceptibility measurements were made at room temperature using Gouy-balance.

  19. Hydrogen production by steam reforming of liquefied natural gas (LNG) over nickel catalysts supported on cationic surfactant-templated mesoporous aluminas

    Science.gov (United States)

    Seo, Jeong Gil; Youn, Min Hye; Park, Sunyoung; Jung, Ji Chul; Kim, Pil; Chung, Jin Suk; Song, In Kyu

    Two types of mesoporous γ-aluminas (denoted as A-A and A-S) are prepared by a hydrothermal method under different basic conditions using cationic surfactant (cetyltrimethylammonium bromide, CTAB) as a templating agent. A-A and A-S are synthesized in a medium of ammonia solution and sodium hydroxide solution, respectively. Ni/γ-Al 2O 3 catalysts (Ni/A-A and Ni/A-S) are then prepared by an impregnation method, and are applied to hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of a mesoporous γ-Al 2O 3 support on the catalytic performance of Ni/γ-Al 2O 3 is investigated. The identity of basic solution strongly affects the physical properties of the A-A and A-S supports. The high surface-area of the mesoporous γ-aluminas and the strong metal-support interaction of supported catalysts greatly enhance the dispersion of nickel species on the catalyst surface. The well-developed mesopores of the Ni/A-A and Ni/A-S catalysts prohibit the polymerization of carbon species on the catalyst surface during the reaction. In the steam reforming of LNG, both Ni/A-A and Ni/A-S catalysts give better catalytic performance than the nickel catalyst supported on commercial γ-Al 2O 3 (Ni/A-C). In addition, the Ni/A-A catalyst is superior to the Ni/A-S catalyst. The relatively strong metal-support interaction of Ni/A-A catalyst effectively suppresses the sintering of metallic nickel and the carbon deposition in the steam reforming of LNG. The large pores of the Ni/A-A catalyst also play an important role in enhancing internal mass transfer during the reaction.

  20. A uranium-based UO_2"+-Mn"2"+ single-chain magnet assembled trough cation-cation interactions

    International Nuclear Information System (INIS)

    Mougel, Victor; Chatelain, Lucile; Hermle, Johannes; Pecaut, Jacques; Mazzanti, Marinella; Caciuffo, Roberto; Colineau, Eric; Tuna, Floriana; Magnani, Nicola; Geyer, Arnaud de

    2014-01-01

    Single-chain magnets (SCMs) are materials composed of magnetically isolated one-dimensional (1D) units exhibiting slow relaxation of magnetization. The occurrence of SCM behavior requires the fulfillment of stringent conditions for exchange and anisotropy interactions. Herein, we report the synthesis, the structure, and the magnetic characterization of the first actinide-containing SCM. The 5f-3d heterometallic 1D chains [{[UO_2(salen)(py)][M(py)_4](NO_3)}]_n, (M=Cd (1) and M=Mn (2); py=pyridine) are assembled trough cation-cation interaction from the reaction of the uranyl(V) complex [UO_2(salen)py][Cp*_2Co] (Cp*=pentamethylcyclopentadienyl) with Cd(NO_3)_2 or Mn(NO_3)_2 in pyridine. The infinite UMn chain displays a high relaxation barrier of 134 ±0.8 K (93 ±0.5 cm"-"1), probably as a result of strong intra-chain magnetic interactions combined with the high Ising anisotropy of the uranyl(V) dioxo group. It also exhibits an open magnetic hysteresis loop at T <6 K, with an impressive coercive field of 3.4 T at 2 K. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. The Free Tricoordinated Silyl Cation Problem

    Directory of Open Access Journals (Sweden)

    Čičak, H.

    2010-03-01

    Full Text Available As the importance and abundance of silicon in our environment is large, it has been thought that silicon might take the place of carbon in forming a host of similar compounds and silicon-based life. However, until today there is no experimental evidence for such a hypothesis and carbon is still unique among the elements in the vast number and variety of compounds it can form. Also, the corresponding derivatives of the two elements show considerable differences in their chemical properties.The essential debate concerning organosilicon chemistry relates to the existence of the free planar tricoordinated silyl cations in condensed phase (R3Si+, in analogy to carbocations (R3C+ which have been known and characterized as free species. Although silyl cations are thermodynamically more stable than their carbon analogs, they are very reactive due to their high inherent electrophilicity and the ability of hypervalent coordination. On the other hand, stabilization by inductive and hyperconjugative effects and larger steric effects of carbocations make them less sensitive to solvation or other environmental effects than silyl cations. Hence, observation of free silyl cations in the condensed phase proved extremely difficult and the actual problem is the question of the degree of the (remaining silyl cation character.The first free silyl cation, trimesitylsilyl cation, and in analogy with it tridurylsilyl cation, were synthesized by Lambert et al. Free silyl cations based on analogy to aromatic ions (homocyclopropenylium and tropylium have also been prepared. However, in these silyl cations the cationic character is reduced by internal π -conjugation. Čičak et al. prepared some silyl-cationic intermediates (Me3Si--CH≡CR+in solid state. With the help of quantum-mechanical calculations it was concluded that these adducts have much more silyl cation than carbocation character.

  2. Understanding CO-stripping mechanism from Ni{sub UPD}/Pt(1 1 0) in view of the measured nickel formal partial charge number upon underpotential deposition on platinum surfaces in sulphate media

    Energy Technology Data Exchange (ETDEWEB)

    Chatenet, Marian [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, LEPMI, UMR 5631 CNRS-INPG-UJF, BP 75, 38402 Saint-Martin d' Heres Cedex (France)], E-mail: Marian.Chatenet@lepmi.inpg.fr; Soldo-Olivier, Yvonne; Chainet, Eric; Faure, Rene [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, LEPMI, UMR 5631 CNRS-INPG-UJF, BP 75, 38402 Saint-Martin d' Heres Cedex (France)

    2007-12-01

    We recently showed nickel-underpotential deposition (Ni-UPD) occurs on polycrystalline or single crystal platinum electrodes in acidic media. Whereas the decoupling of the nickel and hydrogen adsorption/desorption peaks is difficult for low pH, these processes can be better separated for higher pH values, typically pH > 3. However, even for platinum single crystals, high pH solutions do not enable to sufficiently separate nickel from hydrogen phenomena. As a result, electrochemistry alone cannot yield important information about Ni-UPD, such as the formal partial charge number (valency of electrosorption) and the role of the sulphate or hydrogen sulphate anions. So, we decided to couple cyclic voltammetry to electrochemical quartz crystal microbalance (EQCM). EQCM measurements enable to decorrelate the simultaneous hydrogen and nickel adsorption/desorption peaks, which we could not attempt solely with electrochemistry. The coupling between gravimetric and electrochemical measurements allows us to detect the contribution of the anions and thus to isolate that of nickel: nickel coverage can then be determined. Nearly 4/5 Ni{sub UPD} monolayer ({theta}{sub Ni} {approx} 0.8) over platinum is reached at nickel equilibrium potential for high pH solutions (5.5). The QCM and electrochemistry coupling further allows the determination of nickel formal partial charge number: {iota}{sub Ni,EQCM} = 1.3 {+-} 0.13. Direct electrochemistry measurements (Swathirajan and Bruckenstein method) yield: {iota}{sub Ni,Pt(poly)} = 1.5 {+-} 0.17. These two values are close, which validates the electrochemical method for the nickel/platinum system. In consequence, we used Swathirajan and Bruckenstein method for Pt(1 1 0)-(1 x 2) crystal and found: {iota}{sub Ni,Pt(110)} {approx} 1.4 {+-} 0.1. Whatever the system (Ni{sub UPD}/Pt(poly) or Ni{sub UPD}/Pt(1 1 0)-(1 x 2)) or the experimental technique, nickel formal partial charge number is lower than nickel cation charge: {iota}{sub Ni} < z

  3. inner-sphere complexation of cations at the rutile-water interface: A concise surface structural interpretation with the CD and MUSIC model

    Energy Technology Data Exchange (ETDEWEB)

    Ridley, Mora K. [Texas Tech University, Lubbock; Hiemstra, T [Oak Ridge National Laboratory (ORNL); Van Riemsdijk, Willem H. [Wageningen University and Research Centre, The Netherlands; Machesky, Michael L. [Illinois State Water Survey, Champaign, IL

    2009-01-01

    Acid base reactivity and ion-interaction between mineral surfaces and aqueous solutions is most frequently investigated at the macroscopic scale as a function of pH. Experimental data are then rationalized by a variety of surface complexation models. These models are thermodynamically based which in principle does not require a molecular picture. The models are typically calibrated to relatively simple solid-electrolyte solution pairs and may provide poor descriptions of complex multicomponent mineral aqueous solutions, including those found in natural environments. Surface complexation models may be improved by incorporating molecular-scale surface structural information to constrain the modeling efforts. Here, we apply a concise, molecularly-constrained surface complexation model to a diverse suite of surface titration data for rutile and thereby begin to address the complexity of multi-component systems. Primary surface charging curves in NaCl, KCl, and RbCl electrolyte media were fit simultaneously using a charge distribution (CD) and multisite complexation (MUSIC) model [Hiemstra T. and Van Riemsdijk W. H. (1996) A surface structural approach to ion adsorption: the charge distribution (CD) model. J. Colloid Interf. Sci. 179, 488 508], coupled with a Basic Stern layer description of the electric double layer. In addition, data for the specific interaction of Ca2+ and Sr2+ with rutile, in NaCl and RbCl media, were modeled. In recent developments, spectroscopy, quantum calculations, and molecular simulations have shown that electrolyte and divalent cations are principally adsorbed in various inner-sphere configurations on the rutile 110 surface [Zhang Z., Fenter P., Cheng L., Sturchio N. C., Bedzyk M. J., Pr edota M., Bandura A., Kubicki J., Lvov S. N., Cummings P. T., Chialvo A. A., Ridley M. K., Be ne zeth P., Anovitz L., Palmer D. A., Machesky M. L. and Wesolowski D. J. (2004) Ion adsorption at the rutile water interface: linking molecular and macroscopic

  4. Inner-sphere complexation of cations at the rutile-water interface: A concise surface structural interpretation with the CD and MUSIC model

    Science.gov (United States)

    Ridley, Moira K.; Hiemstra, Tjisse; van Riemsdijk, Willem H.; Machesky, Michael L.

    2009-04-01

    Acid-base reactivity and ion-interaction between mineral surfaces and aqueous solutions is most frequently investigated at the macroscopic scale as a function of pH. Experimental data are then rationalized by a variety of surface complexation models. These models are thermodynamically based which in principle does not require a molecular picture. The models are typically calibrated to relatively simple solid-electrolyte solution pairs and may provide poor descriptions of complex multi-component mineral-aqueous solutions, including those found in natural environments. Surface complexation models may be improved by incorporating molecular-scale surface structural information to constrain the modeling efforts. Here, we apply a concise, molecularly-constrained surface complexation model to a diverse suite of surface titration data for rutile and thereby begin to address the complexity of multi-component systems. Primary surface charging curves in NaCl, KCl, and RbCl electrolyte media were fit simultaneously using a charge distribution (CD) and multisite complexation (MUSIC) model [Hiemstra T. and Van Riemsdijk W. H. (1996) A surface structural approach to ion adsorption: the charge distribution (CD) model. J. Colloid Interf. Sci. 179, 488-508], coupled with a Basic Stern layer description of the electric double layer. In addition, data for the specific interaction of Ca 2+ and Sr 2+ with rutile, in NaCl and RbCl media, were modeled. In recent developments, spectroscopy, quantum calculations, and molecular simulations have shown that electrolyte and divalent cations are principally adsorbed in various inner-sphere configurations on the rutile 1 1 0 surface [Zhang Z., Fenter P., Cheng L., Sturchio N. C., Bedzyk M. J., Předota M., Bandura A., Kubicki J., Lvov S. N., Cummings P. T., Chialvo A. A., Ridley M. K., Bénézeth P., Anovitz L., Palmer D. A., Machesky M. L. and Wesolowski D. J. (2004) Ion adsorption at the rutile-water interface: linking molecular and macroscopic

  5. Characterization of the perovskite La0,9Sr0,1Ga0,2O2,85 prepared by cation complexation

    International Nuclear Information System (INIS)

    Reis, S.L.; Grosso, R.L.; Muccillo, E.N.S.

    2012-01-01

    Strontium and magnesium doped lanthanum gallate exhibits perovskite-type structure and high ionic conductivity. Other features of this ceramic material are large electrolytic regime and negligible electronic conductivity. These characteristics are responsible for the potential use of this solid electrolyte in solid oxide fuel cells operating at intermediate temperatures (~∼500-700 deg C). In this work, the composition La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 was prepared by the cation complexation technique aiming to obtain powder and sintered specimens with good chemical and structural homogeneities. X-ray diffraction results evidence that single phase was obtained, within the limitations of the technique, in samples sintered at 1350 deg C/4 h, with relative density above 92%. (author)

  6. Solid phase extraction-inductively coupled plasma spectrometry for adsorption of Co(II) and Ni(II) from radioactive wastewaters by natural and modified zeolites

    International Nuclear Information System (INIS)

    Akbar Malekpour; Mohammad Edrisi; Shamsollah Shirzadi; Saeed Hajialigol

    2011-01-01

    Natural and modified clinoptilolite as low-cost adsorbents have been used for adsorption of Co(II) and Ni(II) from nuclear wastewaters both in batch and continuous experiments. Zeolite X was also synthesized and its ability towards the selected cations was examined. Kinetic and thermodynamic behaviors for the process were investigated and adsorption equilibrium was interpreted in term of Langmuir and Freundlich equations. The effect of various parameters including the initial concentration, temperature, ionic strength and pH of solution were examined to achieve the optimized conditions. The clinoptilolite was shown good sorption potential for Co(II) and Ni(II) ions at pH values 4-6. Based on desorption studies, nearly 74 and 85% of adsorbed Co(II) and Ni(II) were removed from clinoptilolite by HCl. The Na + and NH 4 + forms of clinoptilolite were the best modified forms for the removal of investigated cations. It is concluded that the selectivity of clinoptilolite is higher for Co(II) than Ni(II). The synthesized zeolite showed more ability to remove cobalt and nickel ions from aqueous solution than the natural clinoptilolite. The microwave irradiation was found to be more rapid and effective for ion exchange compared to conventional ion exchange process. (author)

  7. A circular dichroism sensor for Ni{sup 2+} and Co{sup 2+} based on L-cysteine capped cadmium sulfide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Tedsana, Wimonsiri [Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Tuntulani, Thawatchai [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Ngeontae, Wittaya, E-mail: wittayange@kku.ac.th [Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand)

    2015-03-31

    Highlights: • Demonstrated a new efficient sensor platform based quantum dots. • Used chiral quantum dots as CD sensor for the detection of heavy metal ions for the first time. • The proposed CD sensor showed highest selectivity towards Ni{sup 2+} and Co{sup 2+}. • Low detection limits of 7.33 μM and 1.13 μM for Ni{sup 2+} and Co{sup 2+}, respectively. • Can be used in real water samples comparing with ICP-OES. - Abstract: A new circular dichroism sensor for detecting Ni{sup 2+} and Co{sup 2+} was proposed for the first time using chiral chelating quantum dots. The detection principle was based on changing of circular dichroism signals of the chiral quantum dots when forming a chiral complex with Ni{sup 2+} or Co{sup 2+}. L-Cysteine capped cadmium sulfide quantum dots (L-Cyst-CdS QDs) were proposed as a chiral probe. The CD spectrum of L-Cyst-CdS QDs was significantly changed in the presence of Ni{sup 2+} and Co{sup 2+}. On the other hand, other studied cations did not alter the original CD spectrum. Moreover, when increasing the concentration of Ni{sup 2+} or Co{sup 2+}, the intensity of the CD spectrum linearly increased as a function of concentration and could be useful for the quantitative analysis. The proposed CD sensor showed linear working concentration ranges of 10–60 μM and 4–80 μM with low detection limits of 7.33 μM and 1.13 μM for the detection of Ni{sup 2+} and Co{sup 2+}, respectively. Parameters possibly affected the detection sensitivity such as solution pH and incubation time were studied and optimized. The proposed sensor was applied to detect Ni{sup 2+} and Co{sup 2+} in real water samples, and the results agreed well with the analysis using the standard ICP-OES.

  8. Cation depletion by the sodium pump in red cells with pathologic cation leaks. Sickle cells and xerocytes.

    Science.gov (United States)

    Joiner, C H; Platt, O S; Lux, S E

    1986-12-01

    The mechanism by which sickle cells and xerocytic red cells become depleted of cations in vivo has not been identified previously. Both types of cells exhibit elevated permeabilities to sodium and potassium, in the case of sickle cells, when deoxygenated. The ouabain-insensitive fluxes of sodium and potassium were equivalent, however, in both cell types under these conditions. When incubated 18 hours in vitro, sickle cells lost cations but only when deoxygenated. This cation depletion was blocked by ouabain, removal of external potassium, or pretreatment with 4,4'-diisothiocyanostilbene-2,2'-disulfonate, which blocks the increase in cation permeability induced by deoxygenation. The loss of cation exhibited by oxygenated xerocytes similarly incubated was also blocked by ouabain. These data support the hypothesis that the elevated "passive" cation fluxes of xerocytes and deoxygenated sickle cells are not directly responsible for cation depletion of these cells; rather, these pathologic leaks interact with the sodium pump to produce a net loss of cellular cation.

  9. The oxygen deficient Ruddlesden-Popper La3Ni2O7-δ (δ = 0.65) phase: Structure and properties

    International Nuclear Information System (INIS)

    Poltavets, Viktor V.; Lokshin, Konstantin A.; Egami, Takeshi; Greenblatt, Martha

    2006-01-01

    La 3 Ni 2 O 7-δ (δ = 0.65) was synthesized by hydrogen reduction of the parent La 3 Ni 2 O 7 Ruddlesden-Popper nickelate. The crystal structure of La 3 Ni 2 O 6.35 (space group: I4/mmm, a = 3.8742 (1) A and c = 20.055 (1) A) has been determined from powder neutron diffraction data by the Rietveld method for the first time. The oxygen vacancies are located in the LaO x planes between two of the NiO 2 layers. Removal of these oxygen atoms from the parent phase results in a significant (∼0.4 A) shrinkage of the perovskite block along c-direction and splitting of the Ni position. The major part of Ni cations is surrounded by five oxygen atoms forming square pyramids, while the rest are coordinated to six octahedrally arranged oxygen atoms. Over the 170-400 K temperature range, the conductivity of La 3 Ni 2 O 6.35 follows Mott's variable range hopping model modified for a 2D case

  10. Cation binding to 15-TBA quadruplex DNA is a multiple-pathway cation-dependent process.

    Science.gov (United States)

    Reshetnikov, Roman V; Sponer, Jiri; Rassokhina, Olga I; Kopylov, Alexei M; Tsvetkov, Philipp O; Makarov, Alexander A; Golovin, Andrey V

    2011-12-01

    A combination of explicit solvent molecular dynamics simulation (30 simulations reaching 4 µs in total), hybrid quantum mechanics/molecular mechanics approach and isothermal titration calorimetry was used to investigate the atomistic picture of ion binding to 15-mer thrombin-binding quadruplex DNA (G-DNA) aptamer. Binding of ions to G-DNA is complex multiple pathway process, which is strongly affected by the type of the cation. The individual ion-binding events are substantially modulated by the connecting loops of the aptamer, which play several roles. They stabilize the molecule during time periods when the bound ions are not present, they modulate the route of the ion into the stem and they also stabilize the internal ions by closing the gates through which the ions enter the quadruplex. Using our extensive simulations, we for the first time observed full spontaneous exchange of internal cation between quadruplex molecule and bulk solvent at atomistic resolution. The simulation suggests that expulsion of the internally bound ion is correlated with initial binding of the incoming ion. The incoming ion then readily replaces the bound ion while minimizing any destabilization of the solute molecule during the exchange. © The Author(s) 2011. Published by Oxford University Press.

  11. Fe (III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of schiff bases based-on glycine and phenylalanine: Synthesis, magnetic/thermal properties and antimicrobial activity

    Science.gov (United States)

    Sevgi, Fatih; Bagkesici, Ugur; Kursunlu, Ahmed Nuri; Guler, Ersin

    2018-02-01

    Zinc (II), copper (II), nickel (II), cobalt (II) and iron (III) complexes of Schiff bases (LG, LP) derived from 2-hydroxynaphthaldehyde with glycine and phenylalanine were reported and characterized by 1H NMR, 13C NMR, elemental analyses, melting point, FT-IR, magnetic susceptibility and thermal analyses (TGA). TGA data show that iron and cobalt include to the coordinated water and metal:ligand ratio