WorldWideScience

Sample records for metal complexes bearing

  1. Catalytic Kinetics of the Schiff Base Metal Complexes Bearing Side Chain of Cyclic morpholine in Carboxylic Ester Hydrolysis

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Shu-Lin; LI,Min-Jiao; OU,Zhong-Wen; CHEN,Guo-Xu; LIU,Fu-An; XIE,Jia-Qing

    2007-01-01

    It has been reported that two Schiff base transition metal complexes bearing the side chain of the morpholine ring were synthesized and characterized, and two complexes with the same base agent but different metal ions were used as a simulant hydrolase in the catalytic hydrolysis of p-nitrophenyl picolinate in this paper. The mechanism of PNPP catalytic hydrolysis is proposed and supported by the results of the spectral analysis and the kinetic calculation. A kinetic mathematical model, applied to the calculation of the kinetic and thermodynamics parameters of PNPP catalytic hydrolysis, has been established on the foundation of the mechanism proposed. The result of the study shows that the two complexes have a good catalytic activity in PNPP catalytic hydrolysis, and the rate of the PNPP catalytic hydrolysis was increased with the increase of the pH values in the buffer solution and affected by the polarization effect of metal ion of the complexes.

  2. 40 CFR Appendix B to Part 414 - Complexed Metal-Bearing Waste Streams

    Science.gov (United States)

    2010-07-01

    ... (including metallized) Organic pigments, miscellaneous lakes and toners Copper Disperse dyes Acid dyes Direct..., metallized/Azo dye + metal acetate Direct dyes, Azo Disperse dyes, Azo and Vat Organic pigment Green 7/Copper... halide + sodium-lead alloy Nickel Azo dyes, metallized/Azo dye + metal acetate Zinc Organic......

  3. Synthesis, spectroscopic characterization and redox reactivity of some transition metal complexes with salicylaldimines bearing 2,6-di-phenylphenol

    Science.gov (United States)

    Kasumov, V. T.; Köksal, Fevzi

    2004-01-01

    New bidentate N-(2,6-di-phenyl-1-hydroxyphenyl) salicylaldimines bearing X=H and 3,5-di- t-butyl substituents on the salicylaldehyde ring, L xH, and their copper(II) complexes, M(L x) 2, (M=Cu(II), Co(II), Pd(II), Ni(II) and Zn(II)) have been synthesized and characterized by IR, UV/vis, 1H NMR, 13C NMR, ESR spectroscopy, magnetic susceptibility measurements, as well as their oxidation with PbO 2 and reduction (for Cu(L x) 2) with PPh 3 were investigated. ESR studies indicate that oxidation of M(L x) 2 produces ligand-centered M II-phenoxyl radical species. The Cu(L x) 2 complexes, unlike others M(L x) 2, are readily reduced by PPh 3 via intramolecular electron transfer from ligand to copper(II) to give unstable radical intermediates which are converted to another stable secondary radical species. The analysis of ESR spectra of Cu(L x) 2, Co(L 1) 2 and generated phenoxyl radicals are presented.

  4. Transition metal complexes bearing 2,6-bis(imino)pyridyl:Synthesis, structure, ethylene polymerization/oligomerization studies

    Institute of Scientific and Technical Information of China (English)

    SU; Biyun; ZHAO; Jianshe; SUN; Wenhua

    2005-01-01

    A series of new complexes {2,6-bis[1-((2-methyl-4-methoxyphenyl)imino)ethyl]pyridine}MCI2 [M=Fe(Ⅱ) (2), Co(Ⅱ) (3), Ni(Ⅱ) (4), Cu(Ⅱ) (5), Zn(Ⅱ) (6)] have been synthesized. At 25℃, using 500 equiv of methylaluminoxane (MAO), the activities of Fe(Ⅱ), Co(Ⅱ) catalysts can ethylene oligomerization. The effects of polymerization conditions such as reaction temperature,AI/M molar ratio and time on the activity of catalyst have been explored.

  5. Effects of metal-inlay thickness in polyethylene cups with metal-on-metal bearings.

    NARCIS (Netherlands)

    Verdonschot, N.J.J.; Vena, P.; Stolk, J.; Huiskes, R.

    2002-01-01

    A way to prevent polyethylene wear in total hip replacements is to use metal-on-metal bearings. The cup design of these bearings may be a metal inlay in a polyethylene cup. However, these metal inlays are relatively thin and may deform on loading. The purpose of the current study was to determine wh

  6. Oligocyclopentadienyl transition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    de Azevedo, Cristina G.; Vollhardt, K. Peter C.

    2002-01-18

    Synthesis, characterization, and reactivity studies of oligocyclopentadienyl transition metal complexes, namely those of fulvalene, tercyclopentadienyl, quatercyclopentadienyl, and pentacyclopentadienyl(cyclopentadienyl) are the subject of this account. Thermal-, photo-, and redox chemistries of homo- and heteropolynuclear complexes are described.

  7. Conducting metal dithiolate complexes

    DEFF Research Database (Denmark)

    Underhill, A. E.; Ahmad, M. M.; Turner, D. J.;

    1985-01-01

    Further work on the chemical composition of the one-dimensional metallic metal dithiolene complex Li-Pt(mnt) is reported. The electrical conduction and thermopower properties of the nickel and palladium complexes are reported and compared with those of the platinum compound...

  8. Influence of Schiff base and lanthanide metals on the synthesis, stability, and reactivity of monoamido lanthanide complexes bearing two Schiff bases.

    Science.gov (United States)

    Han, Fubin; Teng, Qiaoqiao; Zhang, Yong; Wang, Yaorong; Shen, Qi

    2011-03-21

    The monoamido lanthanide complexes stabilized by Schiff base ligand L(2)LnN(TMS)(2) (L = 3,5-Bu(t)(2)-2-(O)-C(6)H(2)CH═N-8-C(9)H(6)N, Ln = Yb (1), Y (2), Eu (3), Nd (4), and La (5)) were synthesized in good yields by the reactions of Ln[N(TMS)(2)](3) with 1.8 equiv of HL in hexane at room temperature. It was found that the stability of 1-5 depends greatly on the size of the lanthanide metals with the increasing trend of Yb ≈ Y metals of Y and Yb, L''(2)LnN(TMS)(2) (Ln = Yb (13) and Y (14)), and the more stable tris-Schiff base complexes with the large metals of La and Nd, yielded L''(3)Ln as the only product. Complexes 1-14 were fully characterized including X-ray crystal structural analysis. Complexes 1-5, 10, and 14 can serve as the efficient catalysts for addition of amines to carbodiimides, and the catalytic activity is greatly affected by the lanthanide metals with the active sequence of Yb < Y < Eu ≈ Nd ≈ La.

  9. Structural criteria for the rational design of selective ligands. 2. Effect of alkyl substitution on metal ion complex stability with ligands bearing ethylene-bridged ether donors

    Energy Technology Data Exchange (ETDEWEB)

    Hay, B.P.; Zhang, D.; Rustad, J.R. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1996-04-24

    A novel approach is presented for the application and interpretation of molecular methanics calculations in ligand structural design. The methodology yields strain energies that (i) provide a yardstick for the measurements of ligand binding site organization for metal ion complexation and (ii) allow the comparison of any two ligands independent of either the number and type of donor atoms or the identity of the metal ion. Application of this methodology is demonstrated in a detailed examination of the influence of alkyl substitution on the structural organization of ethylene-bridged, bidentate, ether donor ligands for the alkali and alkaline earth cations. Nine cases are examined, including the unsubstituted ethylene bridge (dimethoxyethane), all possible arrangements of individual alkyl groups (monoalkylation, gem-dialkylation, meso-dialkylation, d,l-dialkylation, trialkylation, and tetraalkylation), and both cis and trans attachments of the cyclohexyl group. The calculated degree of binding site organization for metal ion complexation afforded by these connecting structures is shown to correlate with known changes in complex stability caused by alkyl substitution of crown ether macrocycles.

  10. Investigation of tribological and mechanical properties of metal bearings

    Indian Academy of Sciences (India)

    Bekir Sadik Ünlü

    2009-08-01

    Copper, aluminum and tin–lead based alloys are widely used as journal bearing materials in tribological applications. Bronze and brass are widely used as journal bearing materials for copper based alloys. Zamacs find applications as journal bearing materials for zinc based alloys, while duralumines are chosen as journal bearing materials for aluminum based alloys. In addition, white metals are widely used as journal bearing materials for tin–lead based alloys. These alloys ensure properties expected from journal bearings. In this study, tribological and mechanical properties of these journal bearings manufactured by metals were investigated. SAE 1050 steel shaft was used as counter abrader. Experiments were carried out in every 30 min for a total of 150 min by using radial journal bearing wear test rig.

  11. From Metal String Complexes to Metal Wires

    Institute of Scientific and Technical Information of China (English)

    PENG SheMing

    2001-01-01

    @@ Our efforts to extend the metal number from dinuclear metal complexes to linear oligonuclear metal complexes with all-syn form of oligo-( α-pyridyl)amido ligands are successful. The oligonuclear complexes are divided into two systems according their MM bond strength, one is the oligonickel( Ⅱ ) complexes without M-M bond, the other is the oligochromium(Ⅱ) and cobalt(H) complexes with a strong M-M bond. Their structures and magnetic behaviors for various metal complexes with specific metal numbers are summarized. The potential application of these metal complexes as a molecular metal wire is discussed by the band structures of hypothetical onedinensional metal strings based on the polynuclear Cr, Co and Ni complexes. Moreover, self-assembled monolayers of n-alkanethiols are employed as a two-dinensional matrix to isolate the metal string complexes, which exhibit protrusions under the measurements of scanning tunneling microscopy (STM) imaging. The topographic STM images reveal that the protruding features for tricobalt and trichromium complexes are, respectively, 0.3 nm and 0.6 nm higher than that of trinickel complex. The increasing trend in conductivity is consistent with their bond orders, obtained from qualitative EHMO calculations.

  12. From Metal String Complexes to Metal Wires

    Institute of Scientific and Technical Information of China (English)

    PENG; SheMing

    2001-01-01

    Our efforts to extend the metal number from dinuclear metal complexes to linear oligonuclear metal complexes with all-syn form of oligo-( α-pyridyl)amido ligands are successful. The oligonuclear complexes are divided into two systems according their MM bond strength, one is the oligonickel( Ⅱ ) complexes without M-M bond, the other is the oligochromium(Ⅱ) and cobalt(H) complexes with a strong M-M bond. Their structures and magnetic behaviors for various metal complexes with specific metal numbers are summarized. The potential application of these metal complexes as a molecular metal wire is discussed by the band structures of hypothetical onedinensional metal strings based on the polynuclear Cr, Co and Ni complexes. Moreover, self-assembled monolayers of n-alkanethiols are employed as a two-dinensional matrix to isolate the metal string complexes, which exhibit protrusions under the measurements of scanning tunneling microscopy (STM) imaging. The topographic STM images reveal that the protruding features for tricobalt and trichromium complexes are, respectively, 0.3 nm and 0.6 nm higher than that of trinickel complex. The increasing trend in conductivity is consistent with their bond orders, obtained from qualitative EHMO calculations.  ……

  13. Selenophene transition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    White, Carter James [Iowa State Univ., Ames, IA (United States)

    1994-07-27

    This research shows that selenophene transition metal complexes have a chemistry that is similar to their thiophene analogs. Selenophene coordination has been demonstrated and confirmed by molecular structure in both the η5- and the η1(Se)-coordination modes. The reaction chemistry of selenophene complexes closely resembles that of the analogous thiophene complexes. One major difference, however, is that selenophene is a better donor ligand than thiophene making the selenophene complexes more stable than the corresponding thiophene complexes. The 77Se NMR chemical shift values for selenophene complexes fall within distinct regions primarily depending on the coordination mode of the selenophene ligand. In the final paper, the C-H bond activation of η1(S)-bound thiophenes, η1(S)-benzothiophene and η1(Se)-bound selenophenes has been demonstrated. The deprotonation and rearrangement of the η1(E)-bound ligand to the carbon bound L-yl complex readily occurs in the presence of base. Reprotonation with a strong acid gives a carbene complex that is unreactive towards nucleophilic attack at the carbene carbon and is stable towards exposure to air. The molecular structure of [Cp(NO)(PPh3)Re(2-benzothioenylcarbene)]O3SCF3 was determined and contains a Re-C bond with substantial double bond character. Methyl substitution for the thienylcarbene or selenylcarbene gives a carbene that rearranges thermally to give back the η1(E)-bound complex. Based on these model reactions, a new mechanism for the H/D exchange of thiophene over the hydrodesulfurization catalyst has been proposed.

  14. Infection or metal hypersensitivity? The diagnostic challenge of failure in metal-on-metal bearings.

    LENUS (Irish Health Repository)

    Galbraith, John G

    2011-04-01

    The use of second generation metal-on-metal hip articulations has gained favour in the past few years. A hypersensitivity reaction to the metal-on-metal bearing, although rare, is a reported complication and is a novel mode of failure of these implants. Differentiating failure secondary to infection from failure secondary to metal hypersensitivity represents a significant diagnostic challenge. A retrospective review of all cases of hip arthroplasty using metal-on-metal bearings over a 5-year period at a tertiary referral centre identified 3 cases of failure secondary to metal hypersensitivity. Clinical presentation, serological markers, radiological imaging and histological analysis of all cases identified were evaluated. Histological analysis of periprosthetic tissue in all 3 cases identified characteristic features such as perivascular lymphocytic aggregates and chronic inflammation consistent with aseptic lymphocytic vasculitis-associated lesions (ALVAL). This study highlights that failure secondary to metal hypersensitivity must be considered in patients presenting with the reappearance of persistent pain, marked joint effusion, and the development of early osteolysis in the absence of infection.

  15. FIELD TRIP ROADLOG FOR THE BEAR RIVER LANDSLIDE COMPLEX

    OpenAIRE

    McCalpin, James P.

    1987-01-01

    The Bear River Landslide Complex occurs where the unconsolidated sediments of the Bear River Delta have been incised to a depth of 350 to 490 feet (106-150 m) north of Preston, Idaho. The slides are the result of the high pore pressure in confined aquifers in the deltaic sediments. High but variable volumes of groundwater flow and the laterally discontinuous nature of the deltaic sediments result in the varied types of earth movements found within the Landslide Complex. Landslide activity occ...

  16. Electrochemical analysis of metal complexes.

    NARCIS (Netherlands)

    Jong, de H.G.

    1987-01-01

    The present study is concerned with the electroanalytical chemistry of complexes of metals with large ligands. The main purpose was to develop quantitative descriptions of the voltammetric current-potential relation of metal complex systems with different diffusion coefficients of the species involv

  17. Metal-on-metal bearings a clinical practicum

    CERN Document Server

    Jones, Lynne C; Greenwald, A Seth

    2014-01-01

    This book addresses the background and significance of factors potentially influencing clinical and biological outcomes of metal-on-metal hip implants. Includes discussion of reported complications including pseudotumors and other lymphocytic-based responses.

  18. Synthesis, Spectral Characterization, SEM, Antimicrobial, Antioxidative Activity Evaluation, DNA Binding and DNA Cleavage Investigation of Transition Metal(II) Complexes Derived from a tetradentate Schiff base bearing thiophene moiety.

    Science.gov (United States)

    Abdel Aziz, Ayman A; Seda, Sabry H

    2017-03-01

    A novel series of Co(II), Ni(II), Cu(II) and Zn(II) mononuclear complexes have been synthesized involving a potentially tetradentate Schiff base ligand, which was obtained by condensation of 2-aminophenol with 2,5-thiophene-dicarboxaldehyde. The complexes were synthesized via reflux reaction of methanolic solution of the appropriate Schiff base ligand with one equivalent of corresponding metal acetate salt. Based on different techniques including micro analysis, FT-IR, NMR, UV-Vis, ESR, ESI-mass and conductivity measurements, four-coordinated geometry was assigned for all complexes. Spectroscopic data have shown that, the reported Schiff base coordinated to metal ions as a dibasic tetradentate ligand through the phenolic oxygen and the azomethine nitrogen. The antimicrobial activities of the parent ligand and its complexes were investigated by using the agar disk diffusion method. Antioxidation properties of the novel complexes were investigated and it was found that all the complexes have good radical scavenging properties. The binding of complexes to calf thymus DNA (CT-DNA) was investigated by absorption, emission and viscosity measurements. Binding studies have shown that all the complexes interacted with CT-DNA via intercalation mode and the binding affinity varies with relative order as Cu(II) complex > Co(II) complex > Zn(II) complex > Ni(II) complex. Furthermore, DNA cleavage properties of the metal complexes were also investigated. The results suggested the possible utilization of novel complexes for pharmaceutical applications.

  19. Alkane Soluble Transition Metal Complexes.

    Science.gov (United States)

    1983-10-01

    and decomposition of any intermediate, complexes. Cloro - L~r. spectra were recorded in the range 4 000-200 cm𔃻 form solutions of the phosphine PAr5...netathesis quickly showed that the lo~o-complez Is less stable than its cloro -malogue. A detailed Investigatiom of the preparation, charecterlstion and...solvent extraction of products that are believed to be a mixture of several metals, as stationary phases in gas chromatography. isomers of the ortho

  20. Formazans and their metal complexes

    Science.gov (United States)

    Sigeikin, Gennadii I.; Lipunova, Galina N.; Pervova, I. G.

    2006-10-01

    The current data on the structure of formazans in crystals and in solutions are considered and some problems of tautomeric and conformational equilibria are discussed. Some novel classes of formazans synthesised over the past decade are presented. The results of structural studies of formazan complexes with various types of metal coordination are generalised. Examples of synthesis of formazan-containing polymers are given. Special emphasis is placed on analytical and practical applications of formazan derivatives.

  1. Formazans and their metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    Sigeikin, Gennadii I [Interdepartment Centre of Analytical Research in Chemistry, Physics and Biology at the Presidium of the Russian Academy of Sciences (Russian Federation); Lipunova, Galina N [Urals State Technical University, Ekaterinburg (Russian Federation); Pervova, I G [Urals State Forest Engineering University, Ekaterinburg (Russian Federation)

    2006-10-31

    The current data on the structure of formazans in crystals and in solutions are considered and some problems of tautomeric and conformational equilibria are discussed. Some novel classes of formazans synthesised over the past decade are presented. The results of structural studies of formazan complexes with various types of metal coordination are generalised. Examples of synthesis of formazan-containing polymers are given. Special emphasis is placed on analytical and practical applications of formazan derivatives.

  2. A Ruthenium(III)-Oxyl Complex Bearing Strong Radical Character.

    Science.gov (United States)

    Shimoyama, Yoshihiro; Ishizuka, Tomoya; Kotani, Hiroaki; Shiota, Yoshihito; Yoshizawa, Kazunari; Mieda, Kaoru; Ogura, Takashi; Okajima, Toshihiro; Nozawa, Shunsuke; Kojima, Takahiko

    2016-11-02

    Proton-coupled electron-transfer oxidation of a Ru(II) -OH2 complex, having an N-heterocyclic carbene ligand, gives a Ru(III) -O(.) species, which has an electronically equivalent structure of the Ru(IV) =O species, in an acidic aqueous solution. The Ru(III) -O(.) complex was characterized by spectroscopic methods and DFT calculations. The oxidation state of the Ru center was shown to be close to +3; the Ru-O bond showed a lower-energy Raman scattering at 732 cm(-1) and the Ru-O bond length was estimated to be 1.77(1) Å. The Ru(III) -O(.) complex exhibits high reactivity in substrate oxidation under catalytic conditions; particularly, benzaldehyde and the derivatives are oxidized to the corresponding benzoic acid through C-H abstraction from the formyl group by the Ru(III) -O(.) complex bearing a strong radical character as the active species.

  3. Frustration across the periodic table: heterolytic cleavage of dihydrogen by metal complexes.

    Science.gov (United States)

    Bullock, R Morris; Chambers, Geoffrey M

    2017-08-28

    This perspective examines frustrated Lewis pairs (FLPs) in the context of heterolytic cleavage of H2 by transition metal complexes, with an emphasis on molecular complexes bearing an intramolecular Lewis base. FLPs have traditionally been associated with main group compounds, yet many reactions of transition metal complexes support a broader classification of FLPs that includes certain types of transition metal complexes with reactivity resembling main group-based FLPs. This article surveys transition metal complexes that heterolytically cleave H2, which vary in the degree that the Lewis pairs within these systems interact. Many of the examples include complexes bearing a pendant amine functioning as the base with the metal functioning as the hydride acceptor. Consideration of transition metal compounds in the context of FLPs can inspire new innovations and improvements in transition metal catalysis.This article is part of the themed issue 'Frustrated Lewis pair chemistry'. © 2017 The Author(s).

  4. Bear

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The famous physicist made for his scholars this riddle. A fellow encountered a bear in a wasteland. There was nobody else there. Both were frightened and ran away. Fellow to the north, bear to the west. Suddenly the fellow stopped, aimed his gun to the south and shot the bear. What colour was the bear?

  5. Metal complexes with 5-aminotetrazole

    Energy Technology Data Exchange (ETDEWEB)

    Lavrenova, L.G.; Larionov, S.V.; Grankina, Z.A.; Ikorskij, V.N. (AN SSSR, Novosibirsk. Inst. Neorganicheskoj Khimii)

    1983-01-01

    Nitrate and chloride complexes of Co(2), Ni(2), Cu(2), Cd(2), Hg(2), Pb(2) with 5 aminotetrazole (ATE) and compounds Zn(ATE')/sub 2/ and Cd(ATEE')/sub 2/, where ATE' is a 5 aminotetrazole anion, were prepared. On the base of spectroscopic data (spectrophotometry, IR- spectra, EPR and magnetic measurements assumptions on M(2) coordination in complexes are made. Most probably ATE is a bridge ligand which is toined by two nitrogen atoms to various M(2) ions. In Co(2), Ni(2) and Cu(ATE)/sub 3/-Cl/sub 2/ compounds the metal has a distorted actahedral coordination and forms MN/sub 6/ unit, which suggests the interaction of metal ions with ATE nitrogen atoms along the Z-axis. In the Cu(ATE)/sub 2/(NO/sub 3/)/sub 2/ octahedral complex the CuN/sub 4/O/sub 2/ coordination unit is realized at the expense of participation of nitratogroups in coordination.

  6. P-Fluorous Phosphines as Electron-Poor/Fluorous Hybrid Functional Ligands for Precious Metal Catalysts: Synthesis of Rh(I, Ir(I, Pt(II, and Au(I Complexes Bearing P-Fluorous Phosphine Ligands

    Directory of Open Access Journals (Sweden)

    Shin-ichi Kawaguchi

    2017-01-01

    Full Text Available P-Fluorous phosphine (R2PRf, in which the perfluoroalkyl group is directly bonded to the phosphorus atom, is a promising ligand because it has a hybrid functionality, i.e., electron-poor and fluorous ligands. However, examples of P-fluorous phosphine–metal complexes are still rare, most probably because the P-fluorous group is believed to decrease the coordination ability of the phosphines dramatically. In contrast, however, we have succeeded in synthesizing a series of P-fluorous phosphine–coordinated metal complexes such as rhodium, iridium, platinum, and gold. Furthermore, the electronic properties of R2PnC10F21 are investigated by X-ray analysis of PtCl2(Ph2PnC10F212 and the infrared CO stretching frequency of RhCl(CO(R2PnC10F212. IrCl(CO(Ph2PnC10F212- and AuCl(R2PnC10F21-catalyzed reactions are also demonstrated.

  7. Water-soluble ruthenium complexes bearing activity against protozoan parasites.

    Science.gov (United States)

    Sarniguet, Cynthia; Toloza, Jeannette; Cipriani, Micaella; Lapier, Michel; Vieites, Marisol; Toledano-Magaña, Yanis; García-Ramos, Juan Carlos; Ruiz-Azuara, Lena; Moreno, Virtudes; Maya, Juan Diego; Azar, Claudio Olea; Gambino, Dinorah; Otero, Lucía

    2014-06-01

    Parasitic illnesses are major causes of human disease and misery worldwide. Among them, both amebiasis and Chagas disease, caused by the protozoan parasites, Entamoeba histolytica and Trypanosoma cruzi, are responsible for thousands of annual deaths. The lack of safe and effective chemotherapy and/or the appearance of current drug resistance make the development of novel pharmacological tools for their treatment relevant. In this sense, within the framework of the medicinal inorganic chemistry, metal-based drugs appear to be a good alternative to find a pharmacological answer to parasitic diseases. In this work, novel ruthenium complexes [RuCl2(HL)(HPTA)2]Cl2 with HL=bioactive 5-nitrofuryl containing thiosemicarbazones and PTA=1,3,5-triaza-7-phosphaadamantane have been synthesized and fully characterized. PTA was included as co-ligand in order to modulate complexes aqueous solubility. In fact, obtained complexes were water soluble. Their activity against T. cruzi and E. histolytica was evaluated in vitro. [RuCl2(HL4)(HPTA)2]Cl2 complex, with HL4=N-phenyl-5-nitrofuryl-thiosemicarbazone, was the most active compound against both parasites. In particular, it showed an excellent activity against E. histolytica (half maximal inhibitory concentration (IC50)=5.2 μM), even higher than that of the reference drug metronidazole. In addition, this complex turns out to be selective for E. histolytica (selectivity index (SI)>38). The potential mechanism of antiparasitic action of the obtained ruthenium complexes could involve oxidative stress for both parasites. Additionally, complexes could interact with DNA as second potential target by an intercalative-like mode. Obtained results could be considered a contribution in the search for metal compounds that could be active against multiple parasites.

  8. Frustration across the periodic table: heterolytic cleavage of dihydrogen by metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    Bullock, R. Morris; Chambers, Geoffrey M.

    2017-07-24

    This Perspective examines the field of Frustrated Lewis Pairs (FLPs) in the context of transition metal mediated heterolytic cleavage of H2, with a particular emphasis on molecular complexes bearing an intramolecular Lewis base. FLPs have traditionally been associated with group compounds, yet many transition metal reactions support a broader classification of FLPs to include certain types of transition metal complexes with reactivity resembling main group based FLPs. This article surveys transition metal complexes that heterolytically cleave H2, which vary in the degree that the Lewis pairs within these systems interact. Particular attention is focused on complexes bearing a pendant amine function as the base. Consideration of transition metal compounds in the context of FLPs can inspire new innovations and improvements in transition metal catalysis.

  9. Synthesis and Study on the Complexation of Dithidiaza 21-Cown-7- Bearing Appended Coumarin or 1-Aminonaphthene as Sidearms

    Institute of Scientific and Technical Information of China (English)

    SONG Hua-Can; MOU De-Hai; CHEN Yi-Wen; XU Zun-Le

    2003-01-01

    @@ The high toxicity of many transition and post-transition metal ions, especially Hg2+ and Pb2 + , is well recognized and a lot of attention has been paid to control contamination of water supplies by toxic metal ions and to monitor the level of these metal ions in the environment. For the application purpose in controlling and monitoring the concentrations of specific metal ions in a complex matrix continuously and remotely by using ion-selective sensory devices, chemical sensors based on the synthetic fluoroionophores and chromoionophores capable of signaling complexation of metal ions have been reported, [1~ 5], and a series of dithidiaza 21-rown-7 bearing appended coumarin or 1-aminonaphthene as sidearms was synthesized. [6

  10. Shock Hazard Prevention through Self-Healing Insulative Coating on SSA Metallic Bearings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The space suit contains metallic bearings at the wrist, neck, and waist, which are exposed to the space environment. There is a need to maintain a high degree of...

  11. Metal-on-metal bearings in total hip arthroplasties : Influence of cobalt chromium ions on bacterial growth and biofilm formation

    NARCIS (Netherlands)

    Hosman, Anton H.; van der Mei, Henny C.; Bulstra, Sjoerd K.; Busscher, Henk J.; Neut, Danielle

    2009-01-01

    Metal-on-metal (MOM) bearings involving cobalt-chromium (Co-Cr) alloys in total hip arthroplasties are becoming more and more popular due to their low wear. Consequences of corrosion products of Co-Cr alloys are for the most part unclear, and the influence of cobalt and chromium ions on biofilm form

  12. Estimation of debonded area in bearing babbitt metal by C-Scan method

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Gye-jo; Park, Sang-ki [Korea Electric Power Research Inst., Taejeon (Korea); Cha, Seok-ju [Korea South Eastern Power Corp., Seoul (Korea). GEN Sector; Park, Young-woo [Chungnam National Univ., Taejeon (Korea). Mechatronics

    2006-07-01

    The debonding area which had a complex boundary was imaged with a immersion technique, and the acoustic image was compared with the actual area. The amplitude information from focused transducer can discriminate between a defected boundary area and a sound interface of dissimilar metal. The shape of irregular boundary and area was processed by a histogram equalization, after that, through the clustering and labelling, it makes the defect area cleared. Each pixel has ultrasonic intensity rate and represents a position data. The estimation error in measuring debonding area was within 4% by image processing technique. The validity of this immersion method and image equalizing technique has been done for the inspection of power plant turbine's thrust bearings. (orig.)

  13. Contact mechanics and elastohydrodynamic lubrication in a novel metal-on-metal hip implant with an aspherical bearing surface.

    Science.gov (United States)

    Meng, Qingen; Gao, Leiming; Liu, Feng; Yang, Peiran; Fisher, John; Jin, Zhongmin

    2010-03-22

    Diameter and diametral clearance of the bearing surfaces of metal-on-metal hip implants and structural supports have been recognised as key factors to reduce the dry contact and hydrodynamic pressures and improve lubrication performance. On the other hand, application of aspherical bearing surfaces can also significantly affect the contact mechanics and lubrication performance by changing the radius of the curvature of a bearing surface and consequently improving the conformity between the head and the cup. In this study, a novel metal-on-metal hip implant employing a specific aspherical bearing surface, Alpharabola, as the acetabular surface was investigated for both contact mechanics and elastohydrodynamic lubrication under steady-state conditions. When compared with conventional spherical bearing surfaces, a more uniform pressure distribution and a thicker lubricant film thickness within the loaded conjunction were predicted for this novel Alpharabola hip implant. The effects of the geometric parameters of this novel acetabular surface on the pressure distribution and lubricant thickness were investigated. A significant increase in the predicted lubricant film thickness and a significant decrease in the dry contact and hydrodynamic pressures were found with appropriate combinations of these geometric parameters, compared with the spherical bearing surface.

  14. Practice and design of the self-purification system for heavy metals-bearing contaminants

    Institute of Scientific and Technical Information of China (English)

    Qian Guangren

    2008-01-01

    Many minerals in nature have self-purification capacity to hold and stabilize deleterious contaminants into their lattice structures,which can be used for treatment of heavy metals-bearing contaminants.Hydrotalcite Layer Double Hy-droxide(LDH),tobermorite Calcium Silicate Hydrate(CSH)and apatite are ubiquitous minerals in nature,having higher geochemical stability and potential for binding and stabilizing heavy metals.Based on the elucidation of crystal structure property and self-purification principles of the three minerals above,this article discussed how to design the self-purification system of heavy metal-bearing contaminants.

  15. metal complexes of copper(ii)

    African Journals Online (AJOL)

    ABSTRACT. Thermally stable metal complexes based on oligomers were prepared by the reaction ... Besides, coordination compounds of salicylaldehyde Schiff base have proven to be an excellent .... They were insoluble in common organic.

  16. 21 CFR 888.3380 - Hip joint femoral (hemi-hip) trunnion-bearing metal/polyacetal cemented prosthesis.

    Science.gov (United States)

    2010-04-01

    ... metal/polyacetal cemented prosthesis. 888.3380 Section 888.3380 Food and Drugs FOOD AND DRUG... Devices § 888.3380 Hip joint femoral (hemi-hip) trunnion-bearing metal/polyacetal cemented prosthesis. (a) Identification. A hip joint femoral (hemi-hip) trunnion-bearing metal/polyacetal cemented prosthesis is a...

  17. New metal complexes as potential therapeutics.

    Science.gov (United States)

    Zhang, Christiana Xin; Lippard, Stephen J

    2003-08-01

    The many activities of metal ions in biology have stimulated the development of metal-based therapeutics. Cisplatin, as one of the leading metal-based drugs, is widely used in treatment of cancer, being especially effective against genitourinary tumors such as testicular. Significant side effects and drug resistance, however, have limited its clinical applications. Biological carriers conjugated to cisplatin analogs have improved specificity for tumor tissue, thereby reducing side effects and drug resistance. Platinum complexes with distinctively different DNA binding modes from that of cisplatin also exhibit promising pharmacological properties. Ruthenium and gold complexes with antitumor activity have also evolved. Other metal-based chemotherapeutic compounds have been investigated for potential medicinal applications, including superoxide dismutase mimics and metal-based NO donors/scavengers. These compounds have the potential to modulate the biological properties of superoxide anion and nitric oxide.

  18. Note: Radial-thrust combo metal mesh foil bearing for microturbomachinery.

    Science.gov (United States)

    Park, Cheol Hoon; Choi, Sang Kyu; Hong, Doo Euy; Yoon, Tae Gwang; Lee, Sung Hwi

    2013-10-01

    This Note proposes a novel radial-thrust combo metal mesh foil bearing (MMFB). Although MMFBs have advantages such as higher stiffness and damping over conventional air foil bearings, studies related to MMFBs have been limited to radial MMFBs. The novel combo MMFB is composed of a radial top foil, thrust top foils, and a ring-shaped metal mesh damper--fabricated by compressing a copper wire mesh--with metal mesh thrust pads for the thrust bearing at both side faces. In this study, the combo MMFB was fabricated in half-split type to support the rotor for a micro gas turbine generator. The manufacture and assembly process for the half-split-type combo MMFB is presented. In addition, to verify the proposed combo MMFB, motoring test results up to 250,000 rpm and axial displacements as a function of rotational speed are presented.

  19. Fabrication of complex metallic nanostructures by nanoskiving.

    Science.gov (United States)

    Xu, Qiaobing; Rioux, Robert M; Whitesides, George M

    2007-10-01

    This paper describes the use of nanoskiving to fabricate complex metallic nanostructures by sectioning polymer slabs containing small, embedded metal structures. This method begins with the deposition of thin metallic films on an epoxy substrate by e-beam evaporation or sputtering. After embedding the thin metallic film in an epoxy matrix, sectioning (in a plane perpendicular or parallel to the metal film) with an ultramicrotome generates sections (which can be as thin as 50 nm) of epoxy containing metallic nanostructures. The cross-sectional dimensions of the metal wires embedded in the resulting thin epoxy sections are controlled by the thickness of the evaporated metal film (which can be as small as 20 nm) and the thickness of the sections cut by the ultramicrotome; this work uses a standard 45 degrees diamond knife and routinely generates slabs 50 nm thick. The embedded nanostructures can be transferred to, and positioned on, planar or curved substrates by manipulating the thin polymer film. Removal of the epoxy matrix by etching with an oxygen plasma generates free-standing metallic nanostructures. Nanoskiving can fabricate complex nanostructures that are difficult or impossible to achieve by other methods of nanofabrication. These include multilayer structures, structures on curved surfaces, structures that span gaps, structures in less familiar materials, structures with high aspect ratios, and large-area structures comprising two-dimensional periodic arrays. This paper illustrates one class of application of these nanostructures: frequency-selective surfaces at mid-IR wavelengths.

  20. Enantioselective Michael reaction catalyzed by well-defined chiral ru amido complexes: isolation and characterization of the catalyst intermediate, ru malonato complex having a metal-carbon bond.

    Science.gov (United States)

    Watanabe, Masahito; Murata, Kunihiko; Ikariya, Takao

    2003-06-25

    Chiral Ru amido complexes promote asymmetric Michael addition of malonates to cyclic enones, leading to Michael adducts with excellent ee's, in which the chiral Ru amido complexes react with malonates to give isolable catalyst intermediates, chiral Ru malonato complexes bearing a metal bound C-nucleophile.

  1. Novel metals and metal complexes as platforms for cancer therapy.

    Science.gov (United States)

    Frezza, Michael; Hindo, Sarmad; Chen, Di; Davenport, Andrew; Schmitt, Sara; Tomco, Dajena; Dou, Q Ping

    2010-06-01

    Metals are essential cellular components selected by nature to function in several indispensable biochemical processes for living organisms. Metals are endowed with unique characteristics that include redox activity, variable coordination modes, and reactivity towards organic substrates. Due to their reactivity, metals are tightly regulated under normal conditions and aberrant metal ion concentrations are associated with various pathological disorders, including cancer. For these reasons, coordination complexes, either as drugs or prodrugs, become very attractive probes as potential anticancer agents. The use of metals and their salts for medicinal purposes, from iatrochemistry to modern day, has been present throughout human history. The discovery of cisplatin, cis-[Pt(II) (NH(3))(2)Cl(2)], was a defining moment which triggered the interest in platinum(II)- and other metal-containing complexes as potential novel anticancer drugs. Other interests in this field address concerns for uptake, toxicity, and resistance to metallodrugs. This review article highlights selected metals that have gained considerable interest in both the development and the treatment of cancer. For example, copper is enriched in various human cancer tissues and is a co-factor essential for tumor angiogenesis processes. However the use of copper-binding ligands to target tumor copper could provide a novel strategy for cancer selective treatment. The use of nonessential metals as probes to target molecular pathways as anticancer agents is also emphasized. Finally, based on the interface between molecular biology and bioinorganic chemistry the design of coordination complexes for cancer treatment is reviewed and design strategies and mechanisms of action are discussed.

  2. Geochemistry of the Late Neoproterozoic Hadb adh Dayheen ring complex, Central Arabian Shield: Implications for the origin of rare-metal-bearing post-orogenic A-type granites

    Science.gov (United States)

    Moghazi, A. M.; Harbi, H. M.; Ali, K. A.

    2011-11-01

    The Hadb adh Dayheen ring complex (HDRC), Central Arabian Shield, is an alkaline to peralkaline A-type granite complex. It consists of an inner core of monzogranite followed outward by porphyritic alkali feldspar granite (hornblende biotite granite and aegirine riebeckite granite). Field and textural observations indicate that the different granite types were separated from magma reservoir, at different stages, and emplaced at higher levels along pre-existing fractures. The geochemical characteristics indicate that their magma was most plausibly originated by partial melting of juvenile lower crust following collision between East and West Gondwana at the final stage of the Arabian Shield evolution. The alkali feldspar granites have high abundances of albite and fluorite and wide variation of HFSE and REE that indicate interaction with hydrothermal F-rich fluids. Although there are many geochemical, mineralogical and textural evidence of secondary metasomatic alteration superimposed on the granitic rocks, they show textural features such as the arrangement of albite inclusions along growth planes in quartz (snowball texture) and aegirine that indicate early magmatic crystallization of albite. Also, the strong linear positive correlation of Ta vs. Nb and Zr vs. Hf emphasize that the behavior and enrichment of Ta and Nb are largely controlled by magmatic processes. The events that can explain the evolution of these rocks are: (1) during magmatic evolution, F dissolved in the magma and lowered the crystallization temperature causing REE and HFSE to form complexes and thus behave as incompatible elements, (2) prolonged crystallization of the major mineral phases (quartz and feldspar) formed a late-stage magmatic fluid enriched in volatiles (H 2O, F) and trace elements, (3) accessory minerals crystallized from such a phase in the interstices between the major mineral phases, and (4) post-magmatic re-equilibration and formation of secondary albite (Na-metasomatism) has

  3. Special Issue: Practical Applications of Metal Complexes

    Directory of Open Access Journals (Sweden)

    Iztok Turel

    2015-04-01

    Full Text Available In 1913 Alfred Werner received the Nobel Prize in Chemistry for his work that was of great importance for the development of coordination chemistry. In the years that followed numerous complexes consisting of metal ions and organic ligands were isolated, thus building a strong connection between inorganic and organic chemistry. Coordination compounds have many interesting properties which find diverse applications in numerous aspects of human life. Fourteeen contributions were received for this Special Issue covering very different aspects of metal complexes and their practical applications. The highest number of manuscripts deals with the biological activity of complexes which might potentially be used in the clinical practice. Authors have tested their cytotoxicity, antibacterial activity and enzyme inhibition. Their optical properties were studied in view of their potential use in photodynamic therapy. Moreover, optical properties could also be used for bioanalysis. It is also known that metal complexes are useful catalysts and a few such examples are also described herein. Many other interesting properties and facts about the isolated and described complexes are also reported (radioactivity, design of metal-organic frameworks, etc..

  4. Special issue: practical applications of metal complexes.

    Science.gov (United States)

    Turel, Iztok

    2015-04-30

    In 1913 Alfred Werner received the Nobel Prize in Chemistry for his work that was of great importance for the development of coordination chemistry. In the years that followed numerous complexes consisting of metal ions and organic ligands were isolated, thus building a strong connection between inorganic and organic chemistry. Coordination compounds have many interesting properties which find diverse applications in numerous aspects of human life. Fourteeen contributions were received for this Special Issue covering very different aspects of metal complexes and their practical applications. The highest number of manuscripts deals with the biological activity of complexes which might potentially be used in the clinical practice. Authors have tested their cytotoxicity, antibacterial activity and enzyme inhibition. Their optical properties were studied in view of their potential use in photodynamic therapy. Moreover, optical properties could also be used for bioanalysis. It is also known that metal complexes are useful catalysts and a few such examples are also described herein. Many other interesting properties and facts about the isolated and described complexes are also reported (radioactivity, design of metal-organic frameworks, etc.).

  5. Hydrogen storage in complex metal hydrides

    Directory of Open Access Journals (Sweden)

    BORISLAV BOGDANOVIĆ

    2009-02-01

    Full Text Available Complex metal hydrides such as sodium aluminohydride (NaAlH4 and sodium borohydride (NaBH4 are solid-state hydrogen-storage materials with high hydrogen capacities. They can be used in combination with fuel cells as a hydrogen source thus enabling longer operation times compared with classical metal hydrides. The most important point for a wide application of these materials is the reversibility under moderate technical conditions. At present, only NaAlH4 has favourable thermodynamic properties and can be employed as a thermally reversible means of hydrogen storage. By contrast, NaBH4 is a typical non- -reversible complex metal hydride; it reacts with water to produce hydrogen.

  6. Recycling of metal bearing electronic scrap in a plasma furnace

    Science.gov (United States)

    Jarosz, Piotr; Małecki, Stanisław; Gargul, Krzysztof

    2011-12-01

    The recycling of electronic waste and the recovery of valuable components are large problems in the modern world economy. This paper presents the effects of melting sorted electronic scrap in a plasma furnace. Printed circuit boards, cables, and windings were processed separately. The characteristics of the obtained products (i.e., alloy metal, slag, dust, and gases) are presented. A method of their further processing in order to obtain commercial products is proposed. Because of the chemical composition and physical properties, the waste slag is environmentally inert and can be used for the production of abrasives. Process dusts containing large amounts of carbon and its compounds have a high calorific value. That makes it possible to use them for energy generation. The gas has a high calorific value, and its afterburning combined with energy recovery is necessary.

  7. Synthesis of cyclopentadienyl ruthenium complexes bearing pendant chelating picolinates through an electrophilic precursor

    OpenAIRE

    Streu, Craig; Carroll, Patrick J.; Kohli, Rakesh K.; Meggers, Eric

    2008-01-01

    This note reports the facile synthesis of two ruthenium cyclopentadienyl half-sandwich complexes functionalized with coordinating α-picolinates. The synthetic approach involves the (η5-chloromethylcyclopentadienyl)(η6-benzene)ruthenium(II) cation as a useful common building block for cyclopentadienyl complexes bearing anchored ligands.

  8. [Bionic surface design in metal on metal bearings for total hip arthroplasty--optimization of tribological characteristics].

    Science.gov (United States)

    Böhling, U; Scholz, J; Thomas, W; Grundei, H

    2005-04-01

    Bionic systems are aiming to integrate natural observing into mechanical solutions. This has been realized in the design of metal on metal bearing in total hip resurface arthroplasty. The articular side of the femoral cup is covered with a dimple like surface. Under laboratory condition this so called "surf-metal-cup" achieved a reduction of the mechanical wear to almost a third part in comparison to a metal-cup with plane surface. This advantage, caused by the reduced friction-coefficient due to improved hydrodynamic lubrication could also be proved under laboratory conditions. The clinical introduction is expected to offer a significant extension of durability in this prosthetic system and needs to be proved in a long-term study.

  9. Laboratory studies on the tribology of hard bearing hip prostheses: ceramic on ceramic and metal on metal.

    Science.gov (United States)

    Vassiliou, K; Scholes, S C; Unsworth, A

    2007-01-01

    Total hip replacements offer relief to a great many patients every year around the world. With an expected service life of around 25 years on most devices, and with younger and younger patients undergoing this surgery, it is of great importance to understand the mechanisms of their function. Tribological testing of both conventional and hard bearing joint combinations have been conducted in many centres throughout the world, and, after being initially abandoned owing to premature failures, hard bearing combinations have been revisited as viable options for joint replacements. Improved design, manufacturing procedures, and material compositions have led to improved performance over first-generation designs in both metal-on-metal and ceramic-on-ceramic hip prostheses. This paper offers a review of the work conducted in an attempt to highlight the most important factors affecting joint performance and tribology of hard bearing combinations. The tribological performance of these joints is superior to that of conventional metal- or ceramic-on-polymer designs.

  10. Neutral binuclear rare-earth metal complexes with four μ₂-bridging hydrides.

    Science.gov (United States)

    Rong, Weifeng; He, Dongliang; Wang, Meiyan; Mou, Zehuai; Cheng, Jianhua; Yao, Changguang; Li, Shihui; Trifonov, Alexander A; Lyubov, Dmitrii M; Cui, Dongmei

    2015-03-25

    The first neutral rare-earth metal dinuclear dihydrido complexes [(NPNPN)LnH2]2 (2-Ln; Ln = Y, Lu; NPNPN: N[Ph2PNC6H3((i)Pr)2]2) bearing μ2-bridging hydride ligands have been synthesized. In the presence of THF, 2-Y undergoes intramolecular activation of the sp(2) C-H bond to form dinuclear aryl-hydride complex 3-Y containing three μ2-bridging hydride ligands.

  11. PNP-Pincer-Type Phosphaalkene Complexes of Late Transition Metals.

    Science.gov (United States)

    Ozawa, Fumiyuki; Nakajima, Yumiko

    2016-10-01

    This account summarizes our recent studies on PNP-pincer-type phosphaalkene complexes. Phosphaalkenes with a P=C bond possess an extremely low-lying π* orbital and have a marked tendency to engage in strong π back-bonding with transition metals. This particular ligand property provides PNP-pincer complexes with unique structures and reactivities. 2,6-Bis(phosphaethenyl)pyridine leads to the isolation of coordinatively unsaturated complexes of Fe(I) and Cu(I); the former adopts a trigonal monopyramidal configuration, whereas the latter has a strong affinity for PF6- and SbF6- as non-coordinating anions. Unsymmetrical PNP-pincer-type phosphaalkene complexes of Ir(I) bearing a dearomatized pyridine unit instantly cleave the N-H bond of NH3 and the C-H bond of MeCN at room temperature. The dearomatized iridium complexes catalyze the dehydrative coupling of amines with alcohols to afford N-alkylated amines and imines in high yields.

  12. The increase in cobalt release in metal-on-polyethylene hip bearings in tests with third body abrasives.

    Science.gov (United States)

    de Villiers, Danielle; Traynor, Alison; Collins, Simon N; Shelton, Julia C

    2015-09-01

    Hypersensitivity reactions in patients receiving metal-on-metal hip replacements have been attributed to corrosion products as observed by elevated cobalt and chromium ions in the blood. Although the majority of cases are reported in metal-on-metal, incidences of these reactions have been reported in the metal-on-polyethylene patient population. To date, no in vitro study has considered cobalt release for this bearing combination. This study considered four 28 mm and seven 52 mm diameter metal-on-polyethylene bearings tested following ISO standard hip simulator conditions as well as under established abrasive conditions. These tests showed measurable cobalt in all bearings under standard conditions. Cobalt release, as well as polyethylene wear, increased with diameter, increasing from 52 to 255 ppb. The introduction of bone cement particles into the articulation doubled polyethylene wear and cobalt release while alumina particles produced significant damage on the heads demonstrated by cobalt levels of 70,700 ppb and an increased polyethylene wear from a mean value of 9-160 mm(3)/mc. Cobalt release was indicative of head damage and correlated with polyethylene wear at the next gravimetric interval. The removal of third body particles resulted in continued elevated cobalt levels in the 52 mm diameter bearings tested with alumina compared to standard conditions but the bearings tested with bone cement particles returned to standard levels. The polyethylene wear in the bone cement tested bearings also recovered to standard levels, although the alumina tested bearings continued to wear at a higher rate of 475 mm(3)/mc. Cobalt release was shown to occur in metal-on-polyethylene bearings indicating damage to the metal head resulting in increased polyethylene wear. While large diameter metal-on-polyethylene bearings may provide an increased range of motion and a reduced dislocation risk, increased levels of cobalt are likely to be released and this needs to be fully

  13. Interactions between microbial iron reduction and metal geochemistry: effect of redox cycling on transition metal speciation in iron bearing sediments.

    Science.gov (United States)

    Cooper, D Craig; Picardal, Flynn F; Coby, Aaron J

    2006-03-15

    Microbial iron reduction is an important biogeochemical process that can affect metal geochemistry in sediments through direct and indirect mechanisms. With respectto Fe(III) (hydr)oxides bearing sorbed divalent metals, recent reports have indicated that (1) microbial reduction of goethite/ferrihydrite mixtures preferentially removes ferrihydrite, (2) this process can incorporate previously sorbed Zn(II) into an authigenic crystalline phase that is insoluble in 0.5 M HCl, (3) this new phase is probably goethite, and (4) the presence of nonreducible minerals can inhibit this transformation. This study demonstrates that a range of sorbed transition metals can be selectively sequestered into a 0.5 M HCl insoluble phase and that the process can be stimulated through sequential steps of microbial iron reduction and air oxidation. Microbial reduction experiments with divalent Cd, Co, Mn, Ni, Pb, and Zn indicate that all metals save Mn experienced some sequestration, with the degree of metal incorporation into the 0.5 M HCl insoluble phase correlating positively with crystalline ionic radius at coordination number = 6. Redox cycling experiments with Zn adsorbed to synthetic goethite/ferrihydrite or iron-bearing natural sediments indicate that redox cycling from iron reducing to iron oxidizing conditions sequesters more Zn within authigenic minerals than microbial iron reduction alone. In addition, the process is more effective in goethite/ferrihydrite mixtures than in iron-bearing natural sediments. Microbial reduction alone resulted in a -3x increase in 0.5 M HCl insoluble Zn and increased aqueous Zn (Zn-aq) in goethite/ferrihydrite, but did not significantly affect Zn speciation in natural sediments. Redox cycling enhanced the Zn sequestration by approximately 12% in both goethite/ferrihydrite and natural sediments and reduced Zn-aq to levels equal to the uninoculated control in goethite/ferrihydrite and less than the uninoculated control in natural sediments. These

  14. Reaction of bis(o-phosphinophenyl)silane with M(PPh3)4 (M = Ni, Pd, Pt): synthesis and structural analysis of η2-(Si-H) metal(0) and pentacoordinate silyl metal(II) hydride complexes of the Ni triad bearing a PSiP-pincer ligand.

    Science.gov (United States)

    Takaya, Jun; Iwasawa, Nobuharu

    2011-09-21

    Reactions of bis(o-(diphenylphosphino)phenyl)methylsilane with M(PPh(3))(4) (M = Ni, Pd, Pt) were investigated. When M = Ni or Pd, synthesis and isolation of η(2)-(Si-H) complexes of mononuclear Ni(0) and Pd(0) were achieved for the first time as frozen intermediates for oxidative addition of the Si-H bond. Structural analysis by X-ray and NMR spectroscopy disclosed that their η(2)-(Si-H) structures were maintained in both solid and solution states and coordination of the Si-H bond to the metal center was relatively weak. On the other hand, reaction with a platinum(0) complex afforded two kinds of pentacoordinate silyl platinum(II) hydride complexes having a PSiP-pincer ligand, which underwent unique thermal isomerization from a square-pyramidal cis-H-Pt-Si to a trigonal-bipyramidal trans-H-Pt-Si isomer. Mechanistic investigations revealed that this isomerization proceeded via an intramolecular rearrangement process probably through a turnstile rotation.

  15. TDPAC studies on metal-complex ferrimagnets

    Energy Technology Data Exchange (ETDEWEB)

    Ohkubo, Yoshitaka [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.; Abe, Shizuko; Okada, Takuya [and others

    1997-03-01

    TDPAC spectra of {sup 117}In (left-arrow {sup 117}Cd) and {sup 111}Cd (left-arrow {sup 111m}Cd) in the mixed metal complex N(C{sub 4}H{sub 9}){sub 4}(M(II)Fe(III)(C{sub 2}O{sub 4}){sub 3})(M=Fe,Ni), the related substraces and LiNbO{sub 3} have been studied. In this paper, pure potassium iron (III) oxalate was prepared and mixed metal complexes were synthesized by changing amount of reagents and the order added, then observed by TDPAC. 2 mol%Cd was dispersed throughout potassium iron oxalate and potassium nickel oxalate, formulating M(II){sub 0.98}Cd(II){sub 0.02}C{sub 2}O{sub 4}{center_dot}2H{sub 2}O (M=Fe, Ni) with the same crystal structure. The formation reaction of mixed metal complex-Fe(II) was faster than that of iron oxalate. Its mixed metal complex-Ni(II) was slower than that of iron oxalate. The rate of quadrupole oscillation was obtained by {omega}{sub Q}({sup 117}In)=67.3 Mrad/s and {omega}{sub Q}({sup 111}Cd)=29.7 Mrad/s of which values were determined by TDPAC spectra of {sup 117}In and {sup 111}Cd in LiNbO{sub 3} at 4K. The value showed pure ion bond of oxygen coordinated with {sup 117}In and {sup 111}Cd. 0.08 {eta} was determined by TDPAC spectrum of {sup 111}Cd(left-arrow {sup 111m}Cd). The rate of {omega}{sub Q} of mixed metal oxalate complex was larger than 2.3, indicating 5s and 5p orbital electron took part in bond of oxygen of oxalic acid or approaching oxygen ion to In nucleus depend on the structual relaxation in decaying of {sup 117}In(left-arrow {sup 117}Cd). (S.Y.)

  16. Characterization study of heavy metal-bearing phases in MSW slag.

    Science.gov (United States)

    Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki; Motomura, Yoshinobu; Watanabe, Koichiro

    2009-05-30

    Slag products derived from the pyrolysis/melting and plasma/melting treatment of municipal solid waste (MSW) in Japan were examined for the characterization study of heavy metal-bearing phases using petrographic techniques. Detailed microscopic observations revealed that the shapes of heavy metal-rich inclusions are generally spherical to semi-spherical and their sizes range from submicron to scarcely large size spheres (over 100 microm). The experiments (both optical microscopy and electron probe microanalysis) indicated that Fe and Cu participate in mutual substitution and different proportions, and form mainly two-phase Fe-Cu alloys that bound in the silicate glass. This alloy characterizes the composition of more than 80% of the metal-rich inclusions. Other metals and non-metals (such as Pb, Ni, Sb, Sn, P, Si, Al and S) with variable amounts and uneven distributions are also incorporated in the Fe-Cu alloy. In average, the bulk concentration of heavy metals in samples from pyrolysis/melting type is almost six times greater than samples treated under plasma/arc processing. The observations also confirmed that slag from pyrolysis origin contains remarkably higher concentration of metallic inclusions than slag from plasma treatment. In the latter, the metallic compounds are separately tapped from molten slag during the melting treatment that might lead to the generation of safer slag product for end users from environmental viewpoint.

  17. Metal ion concentrations in body fluids after implantation of hip replacements with metal-on-metal bearing--systematic review of clinical and epidemiological studies.

    Directory of Open Access Journals (Sweden)

    Albrecht Hartmann

    Full Text Available INTRODUCTION: The use of metal-on-metal (MoM total hip arthroplasty (THA increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. OBJECTIVE: To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. METHODS: Systematic review of clinical trials (RCTs and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor, patient characteristics as well as study quality characteristics (secondary explanatory factors. RESULTS: Overall, 104 studies (11 RCTs, 93 epidemiological studies totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L. Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. DISCUSSION: Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed "time out" for stemmed large-head MoM-THA and recommend a restricted

  18. Ultrafast photophysics of transition metal complexes.

    Science.gov (United States)

    Chergui, Majed

    2015-03-17

    The properties of transition metal complexes are interesting not only for their potential applications in solar energy conversion, OLEDs, molecular electronics, biology, photochemistry, etc. but also for their fascinating photophysical properties that call for a rethinking of fundamental concepts. With the advent of ultrafast spectroscopy over 25 years ago and, more particularly, with improvements in the past 10-15 years, a new area of study was opened that has led to insightful observations of the intramolecular relaxation processes such as internal conversion (IC), intersystem crossing (ISC), and intramolecular vibrational redistribution (IVR). Indeed, ultrafast optical spectroscopic tools, such as fluorescence up-conversion, show that in many cases, intramolecular relaxation processes can be extremely fast and even shorter than time scales of vibrations. In addition, more and more examples are appearing showing that ultrafast ISC rates do not scale with the magnitude of the metal spin-orbit coupling constant, that is, that there is no heavy-atom effect on ultrafast time scales. It appears that the structural dynamics of the system and the density of states play a crucial role therein. While optical spectroscopy delivers an insightful picture of electronic relaxation processes involving valence orbitals, the photophysics of metal complexes involves excitations that may be centered on the metal (called metal-centered or MC) or the ligand (called ligand-centered or LC) or involve a transition from one to the other or vice versa (called MLCT or LMCT). These excitations call for an element-specific probe of the photophysics, which is achieved by X-ray absorption spectroscopy. In this case, transitions from core orbitals to valence orbitals or higher allow probing the electronic structure changes induced by the optical excitation of the valence orbitals, while also delivering information about the geometrical rearrangement of the neighbor atoms around the atom of

  19. 40 CFR 721.4596 - Diazo substituted carbomonocyclic metal complex.

    Science.gov (United States)

    2010-07-01

    ... metal complex. 721.4596 Section 721.4596 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4596 Diazo substituted carbomonocyclic metal complex. (a) Chemical... as a diazo substituted carbomonocyclic metal complex (PMN P-94-1039) is subject to reporting...

  20. Remarkable catalytic activity of dinitrogen-bridged dimolybdenum complexes bearing NHC-based PCP-pincer ligands toward nitrogen fixation

    Science.gov (United States)

    Eizawa, Aya; Arashiba, Kazuya; Tanaka, Hiromasa; Kuriyama, Shogo; Matsuo, Yuki; Nakajima, Kazunari; Yoshizawa, Kazunari; Nishibayashi, Yoshiaki

    2017-04-01

    Intensive efforts for the transformation of dinitrogen using transition metal-dinitrogen complexes as catalysts under mild reaction conditions have been made. However, limited systems have succeeded in the catalytic formation of ammonia. Here we show that newly designed and prepared dinitrogen-bridged dimolybdenum complexes bearing N-heterocyclic carbene- and phosphine-based PCP-pincer ligands [{Mo(N2)2(PCP)}2(μ-N2)] (1) work as so far the most effective catalysts towards the formation of ammonia from dinitrogen under ambient reaction conditions, where up to 230 equiv. of ammonia are produced based on the catalyst. DFT calculations on 1 reveal that the PCP-pincer ligand serves as not only a strong σ-donor but also a π-acceptor. These electronic properties are responsible for a solid connection between the molybdenum centre and the pincer ligand, leading to the enhanced catalytic activity for nitrogen fixation.

  1. Methyl Complexes of the Transition Metals.

    Science.gov (United States)

    Campos, Jesús; López-Serrano, Joaquín; Peloso, Riccardo; Carmona, Ernesto

    2016-05-01

    Organometallic chemistry can be considered as a wide area of knowledge that combines concepts of classic organic chemistry, that is, based essentially on carbon, with molecular inorganic chemistry, especially with coordination compounds. Transition-metal methyl complexes probably represent the simplest and most fundamental way to view how these two major areas of chemistry combine and merge into novel species with intriguing features in terms of reactivity, structure, and bonding. Citing more than 500 bibliographic references, this review aims to offer a concise view of recent advances in the field of transition-metal complexes containing M-CH3 fragments. Taking into account the impressive amount of data that are continuously provided by organometallic chemists in this area, this review is mainly focused on results of the last five years. After a panoramic overview on M-CH3 compounds of Groups 3 to 11, which includes the most recent landmark findings in this area, two further sections are dedicated to methyl-bridged complexes and reactivity.

  2. Metal ammine complexes for hydrogen storage

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Sørensen, Rasmus Zink; Johannessen, Tue

    2005-01-01

    The hopes of using hydrogen as an energy carrier are severely dampened by the fact that there is still no safe, high-density method available for storing hydrogen. We investigate the possibility of using metal ammine complexes as a solid form of hydrogen storage. Using Mg(NH3)(6)Cl-2 as the example......, we show that it can store 9.1% hydrogen by weight in the form of ammonia. The storage is completely reversible, and by combining it with an ammonia decomposition catalyst, hydrogen can be delivered at temperatures below 620 K....

  3. Novel Microbial Assemblages Dominate Weathered Sulfide-Bearing Rock from Copper-Nickel Deposits in the Duluth Complex, Minnesota, USA.

    Science.gov (United States)

    Jones, Daniel S; Lapakko, Kim A; Wenz, Zachary J; Olson, Michael C; Roepke, Elizabeth W; Sadowsky, Michael J; Novak, Paige J; Bailey, Jake V

    2017-08-15

    The Duluth Complex in northeastern Minnesota hosts economically significant deposits of copper, nickel, and platinum group elements (PGEs). The primary sulfide mineralogy of these deposits includes the minerals pyrrhotite, chalcopyrite, pentlandite, and cubanite, and weathering experiments show that most sulfide-bearing rock from the Duluth Complex generates moderately acidic leachate (pH 4 to 6). Microorganisms are important catalysts for metal sulfide oxidation and could influence the quality of water from mines in the Duluth Complex. Nevertheless, compared with that of extremely acidic environments, much less is known about the microbial ecology of moderately acidic sulfide-bearing mine waste, and so existing information may have little relevance to those microorganisms catalyzing oxidation reactions in the Duluth Complex. Here, we characterized the microbial communities in decade-long weathering experiments (kinetic tests) conducted on crushed rock and tailings from the Duluth Complex. Analyses of 16S rRNA genes and transcripts showed that differences among microbial communities correspond to pH, rock type, and experimental treatment. Moreover, microbial communities from the weathered Duluth Complex rock were dominated by taxa that are not typically associated with acidic mine waste. The most abundant operational taxonomic units (OTUs) were from the genera Meiothermus and Sulfuriferula, as well as from diverse clades of uncultivated Chloroflexi, Acidobacteria, and Betaproteobacteria Specific taxa, including putative sulfur-oxidizing Sulfuriferula spp., appeared to be primarily associated with Duluth Complex rock, but not pyrite-bearing rocks subjected to the same experimental treatment. We discuss the implications of these results for the microbial ecology of moderately acidic mine waste with low sulfide content, as well as for kinetic testing of mine waste.IMPORTANCE Economic sulfide mineral deposits in the Duluth Complex may represent the largest undeveloped

  4. THE BEAR RIVER LANDSLIDE COMPLEX, PRESTON, IDAHO: GEOLOGIC CONSIDERATIONS AND HISTORICAL PERSPECTIVES

    OpenAIRE

    McCalpin, James P.

    1987-01-01

    The Bear River Landslide Complex is a series of earth movements in northern Cache Valley, north of Preston, Idaho. The landslides occur in unconsolidated sediments of the Pleistocene Bear River Delta which formed where the river entered Lakes Bonneville and Provo. The Lake Bonneville delta deposits are up to 490 feet (150 m) thick and consist of a lower alluvial coarse sand and gravel unit, a middle delta front fine sand and silt unit, and an upper pro-delta clay up to 50 feet (15 m) thick. T...

  5. Interactions Between Microbial Iron Reduction and Metal Geochemistry: Effect of Redox Cycling on Transition Metal Speciation in Iron Bearing Sediments

    Energy Technology Data Exchange (ETDEWEB)

    D. Craig Cooper; Flynn W. Picardal; Aaron J. Coby

    2006-02-01

    Microbial iron reduction is an important biogeochemical process that can affect metal geochemistry in sediments through direct and indirect mechanisms. With respect to Fe(III) (hydr)oxides bearing sorbed divalent metals, recent reports have indicated that (1) microbial reduction of goethite/ferrihydrite mixtures preferentially removes ferrihydrite, (2) this process can incorporate previously sorbed Zn(II) into an authigenic crystalline phase that is insoluble in 0.5 M HCl, (3) this new phase is probably goethite, and (4) the presence of nonreducible minerals can inhibit this transformation. This study demonstrates that a range of sorbed transition metals can be selectively sequestered into a 0.5 M HCl insoluble phase and that the process can be stimulated through sequential steps of microbial iron reduction and air oxidation. Microbial reduction experiments with divalent Cd, Co, Mn, Ni, Pb, and Zn indicate that all metals save Mn experienced some sequestration, with the degree of metal incorporation into the 0.5 M HCl insoluble phase correlating positively with crystalline ionic radius at coordination number = 6. Redox cycling experiments with Zn adsorbed to synthetic goethite/ferrihydrite or iron-bearing natural sediments indicate that redox cycling from iron reducing to iron oxidizing conditions sequesters more Zn within authigenic minerals than microbial iron reduction alone. In addition, the process is more effective in goethite/ferrihydrite mixtures than in iron-bearing natural sediments. Microbial reduction alone resulted in a ~3× increase in 0.5 M HCl insoluble Zn and increased aqueous Zn (Zn-aq) in goethite/ferrihydrite, but did not significantly affect Zn speciation in natural sediments. Redox cycling enhanced the Zn sequestration by ~12% in both goethite/ferrihydrite and natural sediments and reduced Zn-aq to levels equal to the uninoculated control in goethite/ferrihydrite and less than the uninoculated control in natural sediments. These data suggest

  6. Unique chemical properties of metal-carbon bonds in metal-carboranyl and metal-carboryne complexes

    Institute of Scientific and Technical Information of China (English)

    QIU ZaoZao; XIE ZuoWei

    2009-01-01

    The metal-carbon bonds in metal-carboranyl and metal-carboryne complexes behave very differently from those in classical organometallic complexes. The unique electronic and steric properties of icosahedral carboranyl moiety make the M-C bond in metal-carboranyl complexes inert toward unsaturated molecules, and on the other hand, the sterically demanding carborane cage can induce unexpected C-C coupling reactions. The M-C bonds in metal-carboryne complexes are, however, active toward various kinds of unsaturated molecules and the reactivity patterns are dependent upon the electronic configurations of the metal ions. This account provides an overview of our recent work in this area.

  7. Unique chemical properties of metal-carbon bonds in metal-carboranyl and metal-carboryne complexes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The metal-carbon bonds in metal-carboranyl and metal-carboryne complexes behave very differently from those in classical organometallic complexes. The unique electronic and steric properties of ico-sahedral carboranyl moiety make the M-C bond in metal-carboranyl complexes inert toward unsaturated molecules, and on the other hand, the sterically demanding carborane cage can induce unexpected C-C coupling reactions. The M-C bonds in metal-carboryne complexes are, however, active toward various kinds of unsaturated molecules and the reactivity patterns are dependent upon the electronic configurations of the metal ions. This account provides an overview of our recent work in this area.

  8. Energetic characteristics of transition metal complexes.

    Science.gov (United States)

    Wojewódka, Andrzej; Bełzowski, Janusz; Wilk, Zenon; Staś, Justyna

    2009-11-15

    Ten transition metal nitrate and perchlorate complexes of hydrazine and ethylenediamine were synthesized, namely [Cu(EN)(2)](ClO(4))(2), [Co(EN)(3)](ClO(4))(3), [Ni(EN)(3)](ClO(4))(2), [Hg(EN)(2)](ClO(4))(2), [Cr(N(2)H(4))(3)](ClO(4))(3), [Cd(N(2)H(4))(3)](ClO(4))(2), [Ni(N(2)H(4))(3)](NO(3))(2), [Co(N(2)H(4))(3)](NO(3))(3), [Zn(N(2)H(4))(3)](NO(3))(2), and [Cd(N(2)H(4))(3)](NO(3))(2) based on the lines of the literature reported methods. All of them were tested with applying underwater detonation test and further compared to the typical blasting explosives: RDX, HMX, TNT and PETN. From the above presented complexes [Ni(N(2)H(4))(3)](NO(3))(2) (called NHN) and [Co(N(2)H(4))(3)](NO(3))(3) (called CoHN) are known as primary explosives and can be used as the standard explosives. Explosion parameters, such as shock wave overpressure, shock wave energy equivalent and bubble energy equivalent, were determined. Evaluated energetic characteristics of the tested compounds are comparable to those of the classic high explosives and are even enhanced in some cases.

  9. Bidirectional photoinduced energy transfer in nanoassemblies of quantum dots and luminescent metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    Ramachandra, Srinidhi; Reinhoudt, David N. [Twente Univ., Entschede (Netherlands). Lab. of Supramolecular Chemistry and Technology and MESA Inst. of Nanotechnology; Strassert, Cristian Alejandro [Muenster Univ. (Germany). Physikalisches Inst. and Center for Nanotechnology (CeNTech); Vanmaekelbergh, Daniel [Utrecht Univ. (Netherlands). Condensed Matter and Interfaces; Cola, Luisa de [Twente Univ., Entschede (Netherlands). Lab. of Supramolecular Chemistry and Technology and MESA Inst. of Nanotechnology; Muenster Univ. (Germany). Physikalisches Inst. and Center for Nanotechnology (CeNTech)

    2014-02-15

    This work describes the synthesis and photophysical characterization of Ir(III) and Ru(II) complexes bearing terminal amino groups, which act as anchoring units for the attachment to quantum dots, QDs. The photophysical properties of the metal complexes in combination with different types of QDs, allows directional photoinduced processes in the assemblies. In particular, we show photoinduced energy transfer from the luminescent excited Ir(III) unit to the CdTe nanocrystals, with an efficiency of 40 %. The directionality was then inverted by employing an emitting Ru(II) complex as energy acceptor, in combination with photoluminescent CdSe/ZnS quantum dots. The efficiency of the photoinduced energy transfer from the nanocrystals to the Ru(II) center was estimated to be as high as 75 %. This work provides model systems for nanoassemblies based on quantum dots and metal complexes for optoelectronic applications, and as active light-harvesting systems. (orig.)

  10. Electron Capture Dissociation of Trivalent Metal Ion-Peptide Complexes

    National Research Council Canada - National Science Library

    Flick, Tawnya G; Donald, William A; Williams, Evan R

    2013-01-01

    .... ECD of these doubly charged complexes containing MT results in significantly higher electron capture efficiency and sequence coverage than peptide-divalent metal ion complexes that have the same net charge...

  11. Five-year follow-up of a prospective randomised trial comparing ceramic-on-metal and metal-on-metal bearing surfaces in total hip arthroplasty.

    Science.gov (United States)

    Schouten, R; Malone, A A; Frampton, C M; Tiffen, C; Hooper, G

    2017-10-01

    The primary aim of this independent prospective randomised trial was to compare serum metal ion levels for ceramic-on-metal (CoM) and metal-on-metal (MoM) bearing surfaces in total hip arthroplasty (THA). Our one-year results demonstrated elevation in metal ion levels above baseline with no significant difference between the CoM and MoM groups. This paper reviews the five-year data. The implants used in each patient differed only in respect to the type of femoral head (ceramic or metal). At five-year follow-up of the 83 enrolled patients, data from 67 (36 CoM, 31 MoM) was available for comparison. The mean serum cobalt (Co) and chromium (Cr) ion levels remained above baseline in both groups (CoM: Co 1.16 μg/l (0.41 to 14.67), Cr 1.05 μg/l (0.16 to 12.58); MoM: Co 2.93 μg/l (0.35 to 30.29), Cr 1.85 μg/l (0.36 to 17.00)) but the increase was significantly less in the CoM cohort (Co difference p = 0.001, Cr difference p = 0.002). These medium-term results, coupled with lower revision rates from national joint registries, suggest that the performance of CoM THA may be superior to that of MoM. While both bearing combinations have since been withdrawn these results provide useful information for planning clinical surveillance of CoM THAs and warrants continued monitoring. Cite this article: Bone Joint J 2017;99-B:1298-1303. ©2017 The British Editorial Society of Bone & Joint Surgery.

  12. Metal speciation dynamics and bioavailability: Inert and labile complexes

    Energy Technology Data Exchange (ETDEWEB)

    Van Leeuwen, H.P.

    1999-11-01

    The free-ion activity model for the biouptake of metals from complex media is limited to cases where mass transfer is not flux-determining. This paper considers the simultaneous effects of bioconversion kinetics and metal transport in the medium coupled with metal complex dissociation kinetics. For the two kinetically limiting situations of inert and fully labile complexes, the bioavailabilities of bioinactive metal complexes are analyzed under conditions where (i) the actual biouptake follows a Michaelis-Menten type of steady-state flux and (ii) the supply of free metal is governed by diffusion of free metal or coupled diffusion of the different labile metal species. The resulting steady-site fluxes are given in terms of two fundamental quantities, i.e., the relative bioaffinity parameter (a) and the ratio between the limiting uptake flux and the limiting transport flux (b). For labile complexes, these variables are differentiated by a complexation parameter defined by the ration between the free metal on activity and the total labile metal activity. Limits of the uptake flux for extreme values of the bioaffinity parameter a and the limiting flux ratio b are easily derived from the general flux expression. The analysis precisely shows under what conditions labile complex species contribute to the biouptake process or, equivalently, under what conditions the free-ion activity model is not obeyed.

  13. Melanite garnet-bearing nepheline syenite minor intrusion in Mawpyut ultramafic–mafic complex, Jaintia Hills, Meghalaya

    Indian Academy of Sciences (India)

    Monoj Maitra; J S David; S Bhaduri

    2011-12-01

    Mawpyut igneous suite in Jaintia Hills of Meghalaya plateau comprises differentiated suite of ultramafic–mafic rocks. The complex differs from other ultramafic–alkaline–carbonatite igneous emplacements of Shillong plateau and Mikir Hills like Jesra, Sung, Samchampi complexes, by the absence of alkaline–carbonatite rocks as major litho-units. Melanite garnet-bearing nepheline syenite, occurs as late phase minor intrusion in Mawpyut igneous complex, posseses alkaline character and shows inubiquitous relation with the host ultramafic–mafic rocks. On the other hand, this alkaline intrusive bodies of the Mawpyut igneous complex shows chemico-mineralogical resemblance with garnet-bearing nepheline syenite, ijolite litho-members of Jesra, Sung, Samchampi complexes of the region. It is interpreted that melanite garnet-bearing nepheline syenite intrusion in Mawpyut is contemporaneous with Jesra, Sung, Samchampi ultramafic–alkaline–carbonatite complexes and the host rocks of Mawpyut complex is an earlier magmatic activity possibly from a comparatively least enriched source.

  14. Complexation of trichlorosalicylic acids by alkaline and first row transition metals as a switch for their antibacterial activity

    KAUST Repository

    Kumar, Vijay

    2017-09-14

    3,5,6-trichlorosalicylic acid (TCSA) does not show a good antibacterial activity. In contrast, here metal complexes with TCSA have shown better antibacterial activity for selected bacterial strains with a good degree of selectivity. Amongst the eight synthesized essential metal complexes complexed with TCSA, Mn(II)-TCSA and Ni(II)-TCSA have been found to be more effective with MIC range 20-50 µg/L as compared to control (chloramphenicol). The activity of an individual complex against different microbes was not found to be identical, indicating the usage of an individual metal chelate against a targeted bacterial strain. Further, the protein (BSA) binding constant of TCSA and its metal complexes were determined and ordered as Ca(II)-TCSA > Cu(II)-TCSA > Mg(II)-TCSA >> Mn(II)-TCSA >> Zn(II)-TCSA >>> Ni(II)-TCSA >>> Co(II)-TCSA > Fe(II)-TCSA > TCSA. The present study has confirmed enhanced antibacterial activities and binding constants for metal chelates of TCSA as compared to free TCSA, which seems directly related with the antioxidant activities of these complexes. Further, bearing the ambiguity related to the structural characterization of the metal complexed with TCSA ligands, DFT calculations have been used as the tool to unravel the right environment around the metals, studying basically the relative stability of square planar and octahedral metal complexes with TCSA.

  15. Asymmetric hydrogenation of quinazolinium salts catalysed by halide-bridged dinuclear iridium complexes bearing chiral diphosphine ligands.

    Science.gov (United States)

    Kita, Yusuke; Higashida, Kosuke; Yamaji, Kenta; Iimuro, Atsuhiro; Mashima, Kazushi

    2015-03-14

    Asymmetric hydrogenation of quinazolinium salts was catalysed by halogen-bridged dinuclear iridium complexes bearing chiral diphosphine ligands, yielding tetrahydroquinazoline and 3,4-dihydroquinazoline with high enantioselectivity. A derivative of chiral dihydroquinazoline was used as a chiral NHC ligand.

  16. Alkoxy-Siloxide Metal Complexes: Precursors to Metal Silica, Metal Oxide Silica, and Metal Silicate Materials.

    Science.gov (United States)

    Terry, Karl William

    The alkoxy-siloxide complexes M (OSi(O ^{rm t}Bu)_3 ]_4 (M = Ti(1), Zr(2), Hf(3)), were prepared by reaction with their respective metal diethylamides. These compounds readily undergo low-temperature decomposition to their respective metal oxide silica materials rm(MO_2{cdot}4SiO_2). The volatile products of the thermolysis of 2 (ca. 200 ^circC) were isobutylene (11.7 equiv) and water (5.4 equiv). The rm ZrO _2{cdot}4SiO_2 material from the decomposition of 2 at 400^circ C was amorphous until ca. 1100^ circC where crystallization of t-ZrO _2 occurred. After thermolysis to 1500 ^circC, t-ZrO_2 and cristobalite were the major products with minor amounts of m-ZrO_2. The rm HfO_2{cdot}4SiO_2 material from the decomposition of 3 at 400^ circC was amorphous until ca. 1000 ^circC where crystallization of c/t -HfO_2 was observed. Thermolysis to 1460^circC yielded c/t -HfO_2, m-HfO_2, and minor amounts of cristobalite. The crystallization of anatase in the rm TiO_2{cdot }4SiO_2 material from decomposed 1 at 400^circC was apparent after thermolysis to 1000^circC. Thermolysis to 1400^circC gave a mixture of anatase, rutile, and cristobalite. Compound 2 was decomposed in xylenes and yielded a transparent gel which was isolated as a white powder upon drying in vacuuo. The compounds [ Me _2AlOSi(O^{t}Bu)_3] _2 (4) and [( ^{t}BuO)MeAlOSi(O^{t}Bu) _3]_2 (5) were structurally characterized and contain bent and planar rm Al_2O_2 four membered rings, respectively. Both 4 and 5 yield isobutylene upon thermolysis (ca. 200 ^circC) and the crystallization of mullite occurs at 1034^circC and 1017^circC, respectively (by DTA). The solution thermolysis of 4 in refluxing toluene yields an opaque white gel. The crystallization of mullite occurs at 1029^circC (by DTA). The compounds [ CuOSi(O ^{t}Bu)_3]_{n } (6) and [ CuOSi(O ^{t}Bu)_2Ph]_4 (7) were prepared by reaction with [ CuO^{t}Bu]_4. The thermolysis of 6 at 1000^circ C under argon gave Cu^circ and amorphous silica and thermolysis under

  17. Lability of nanoparticulate metal complexes in electrochemical speciation analysis

    NARCIS (Netherlands)

    Leeuwen, van Herman P.; Town, Raewyn M.

    2016-01-01

    Lability concepts are elaborated for metal complexes with soft (3D) and hard (2D) aqueous nanoparticles. In the presence of a non-equilibrium sensor, e.g. a voltammetric electrode, the notion of lability for nanoparticulate metal complexes, M-NP, reflects the ability of the M-NP to maintain

  18. Lability of nanoparticulate metal complexes in electrochemical speciation analysis

    DEFF Research Database (Denmark)

    van Leeuwen, Herman P.; Town, Raewyn M.

    2016-01-01

    Lability concepts are elaborated for metal complexes with soft (3D) and hard (2D) aqueous nanoparticles. In the presence of a non-equilibrium sensor, e.g. a voltammetric electrode, the notion of lability for nanoparticulate metal complexes, M-NP, reflects the ability of the M-NP to maintain equil...

  19. Enthalpies of Formation of Noble Metal Binary Alloys Bearing Rh or Ir

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The modified embedded atom method proposed by authors has been applied to calculating the enthalpies of formationof random alloys and the ordered intermetallic compounds for noble metal binary systems bearing Rh or lr. The presentresults are in good agreement with those of Miedema theory, available experiments and the first-principles quantummechanics calculations. The present results indicate that Cu-Rh, Cu-lr, Ag-Rh, Ag-lr, Au-Rh, Au-lr, Pd-Rh and Pd-lrsystems are repulsive, however, Ni-Rh, Ni-lr, Pt-lr, Pt-Rh and Rh-lr systems form solid solutions and Ni-Rh, Ni-lrand Pt-Rh show ordering tendency.

  20. Recognition Interactions of Metal-complexing Imprinted Polymer

    Institute of Scientific and Technical Information of China (English)

    Ying LIU; Guo Sheng DING; Jun De WANG

    2005-01-01

    Molecularly imprinted polymer, exhibiting considerable enantioselectivity for L-mandelic acid, was prepared using metal coordination-chelation interaction. By evaluating the recognition characteristics in the chromatographic mode, the recognition interactions were proposed: specific and nonspecific metal coordination-chelation interaction and hydrophobic interaction were responsible for substrate binding on metal-complexing imprinted polymer; while the selective recognition only came from specific metal coordination-chelation interaction and specific hydrophobic interaction.

  1. RutheniumII Complexes bearing Fused Polycyclic Ligands: From Fundamental Aspects to Potential Applications

    Directory of Open Access Journals (Sweden)

    Ludovic Troian-Gautier

    2014-04-01

    Full Text Available In this review, we first discuss the photophysics reported in the literature for mononuclear ruthenium complexes bearing ligands with extended aromaticity such as dipyrido[3,2-a:2',3'-c]phenazine (DPPZ, tetrapyrido[3,2-a:2',3'-c:3'',2''-h:2''',3'''-j]-phenazine (TPPHZ,  tetrapyrido[3,2-a:2',3'-c:3'',2''-h:2''',3'''-j]acridine (TPAC, 1,10-phenanthrolino[5,6-b]1,4,5,8,9,12-hexaazatriphenylene (PHEHAT 9,11,20,22-tetraaza- tetrapyrido[3,2-a:2',3'-c:3'',2''-l:2''',3'''-n]pentacene (TATPP, etc. Photophysical properties of binuclear and polynuclear complexes based on these extended ligands are then reported. We finally develop the use of binuclear complexes with extended π-systems for applications such as photocatalysis.

  2. Rare-earth dialkyl and dihydride complexes bearing monoanionic ancillary ligands

    Institute of Scientific and Technical Information of China (English)

    CHENG JianHua; HOU ZhaoMin

    2011-01-01

    Rare-earth elements,including scandium,yttrium,and the lanthanides (La-Lu),possess unique chemical and physical properties,and constitute one of the last frontiers in the periodic table.Rare-earth elements are vital for many high-tech industry products such as smartphones and electric cars.However,the fundamental chemistry of the rareearth elements has been explored to a far less extent.The first organo rare-earth complexes Cp3Ln (1,Figure 1),which bear three cyclopentadienyl (Cp) ligands,were reported in the early 1950s [1],but these complexes did not receive much attention because of the lack of significant reactivity.In the early 1980s,the alkyl and hydride complexes supported by two cyclopentadienyl ligands (such as 2in Figure 1) were reported [2].

  3. SYNTHESIS AND CHARACTERIZATION OF SALICYLALDAZINE AND ITS METAL (II) COMPLEXES DERIVED FROM METAL (II) CHLORIDES

    OpenAIRE

    Jamila wazir

    2016-01-01

    The salicylaldazine (ligand) and its metal (II) complexes like copper (II), nickel (II), zinc (II), cobalt (II) and manganese (II) complexes has been synthesized and characterized by different techniques using FTIR, UV-VIS spectroscopy. The ligand (salicylaldazine) is synthesized by the condensation reaction of salicylaldehyde and hydrazine sulfate. The salicylaldazine metal (II) complexes like Cu (II) , Ni(II), Zn (II), Co(II), Mn(II) were prepared by using metal (II) chloride in dioxane. Th...

  4. Coexistence of two thermally induced intramolecular electron transfer processes in a series of metal complexes [M(Cat-N-BQ)(Cat-N-SQ)]/[M(Cat-N-BQ)2] (M = Co, Fe, and Ni) bearing non-innocent catechol-based ligands: a combined experimental and theoretical study.

    Science.gov (United States)

    Evangelio, Emi; Bonnet, Marie-Laure; Cabañas, Miquel; Nakano, Motohiro; Sutter, Jean-Pascal; Dei, Andrea; Robert, Vincent; Ruiz-Molina, Daniel

    2010-06-11

    The different thermally induced intermolecular electron transfer (IET) processes that can take place in the series of complexes [M(Cat-N-BQ)(Cat-N-SQ)]/[M(Cat-N-BQ)(2)], for which M = Co (2), Fe (3) and Ni(4), and Cat-N-BQ and Cat-N-SQ denote the mononegative (Cat-N-BQ(-)) or dinegative (Cat-N-SQ(2-)) radical forms of the tridentate Schiff-base ligand 3,5-di-tert-butyl-1,2-quinone-1-(2-hydroxy-3,5-di-tert-butylphenyl)imine, have been studied by variable-temperature UV/Vis and NMR spectroscopies. Depending on the metal ion, rather different behaviors are observed. Complex 2 has been found to be one of the few examples so far reported to exhibit the coexistence of two thermally induced electron transfer processes, ligand-to-metal (IET(LM)) and ligand-to-ligand (IET(LL)). IET(LL) was only found to take place in complex 3, and no IET was observed for complex 4. Such experimental studies have been combined with ab initio wavefunction-based CASSCF/CASPT2 calculations. Such a strategy allows one to solicit selectively the speculated orbitals and to access the ground states and excited-spin states, as well as charge-transfer states giving additional information on the different IET processes.

  5. Metal Complexes of Quinolone Antibiotics and Their Applications: An Update

    Directory of Open Access Journals (Sweden)

    Valentina Uivarosi

    2013-09-01

    Full Text Available Quinolones are synthetic broad-spectrum antibiotics with good oral absorption and excellent bioavailability. Due to the chemical functions found on their nucleus (a carboxylic acid function at the 3-position, and in most cases a basic piperazinyl ring (or another N-heterocycle at the 7-position, and a carbonyl oxygen atom at the 4-position quinolones bind metal ions forming complexes in which they can act as bidentate, as unidentate and as bridging ligand, respectively. In the polymeric complexes in solid state, multiple modes of coordination are simultaneously possible. In strongly acidic conditions, quinolone molecules possessing a basic side nucleus are protonated and appear as cations in the ionic complexes. Interaction with metal ions has some important consequences for the solubility, pharmacokinetics and bioavailability of quinolones, and is also involved in the mechanism of action of these bactericidal agents. Many metal complexes with equal or enhanced antimicrobial activity compared to the parent quinolones were obtained. New strategies in the design of metal complexes of quinolones have led to compounds with anticancer activity. Analytical applications of complexation with metal ions were oriented toward two main directions: determination of quinolones based on complexation with metal ions or, reversely, determination of metal ions based on complexation with quinolones.

  6. Metal complexes of quinolone antibiotics and their applications: an update.

    Science.gov (United States)

    Uivarosi, Valentina

    2013-09-11

    Quinolones are synthetic broad-spectrum antibiotics with good oral absorption and excellent bioavailability. Due to the chemical functions found on their nucleus (a carboxylic acid function at the 3-position, and in most cases a basic piperazinyl ring (or another N-heterocycle) at the 7-position, and a carbonyl oxygen atom at the 4-position) quinolones bind metal ions forming complexes in which they can act as bidentate, as unidentate and as bridging ligand, respectively. In the polymeric complexes in solid state, multiple modes of coordination are simultaneously possible. In strongly acidic conditions, quinolone molecules possessing a basic side nucleus are protonated and appear as cations in the ionic complexes. Interaction with metal ions has some important consequences for the solubility, pharmacokinetics and bioavailability of quinolones, and is also involved in the mechanism of action of these bactericidal agents. Many metal complexes with equal or enhanced antimicrobial activity compared to the parent quinolones were obtained. New strategies in the design of metal complexes of quinolones have led to compounds with anticancer activity. Analytical applications of complexation with metal ions were oriented toward two main directions: determination of quinolones based on complexation with metal ions or, reversely, determination of metal ions based on complexation with quinolones.

  7. Detection of MgCn in IRC + 10216: A new metal-bearing free radical

    Science.gov (United States)

    Ziurys, L. M.; Apponi, A. J.; Guelin, M.; Cernicharo, J.

    1995-01-01

    A new metal-containing molecule, MgCN, has been detected toward the late-type star IRC + 10216, using the NRAO 12 m and IRAM 30 m telescopes. The N = 11 approaches 10, 10 approaches 9, and 9 approaches 8 transtions of this species which has a (sup 2)Sigma(sup +) ground state, have been observed in the outer envelope of this object at 3 mm. For the N = 11 approaches 10 transitions, the two spin-rotation components are clearly resolved and conclusively identify this new radical. These measurements imply a column of density for MgCN of N(sub tot) approximately 10(exp 12)/sq cm in the outer shell, which corresponds to a fractional abundance of f approximately 7x10(exp -10). This molecule, the metastable isomer of MgNC, is the third metal-bearing species thus far identified in the outer shell of IRC + 10216, and its detection implies a ratio of MgNC/MgCN approximately 22/1. MgCN may be formed through a reaction scheme involving magnesium and HNC or CN, both prominent outer shell molecules, or through synthesis on grains.

  8. Metal flux from hydrothermal vents increased by organic complexation

    Science.gov (United States)

    Sander, Sylvia G.; Koschinsky, Andrea

    2011-03-01

    Hydrothermal vents in the sea floor release large volumes of hot, metal-rich fluids into the deep ocean. Until recently, it was assumed that most of the metal released was incorporated into sulphide or oxide minerals, and that the net flux of most hydrothermally derived metals to the open ocean was negligible. However, mounting evidence suggests that organic compounds bind to and stabilize metals in hydrothermal fluids, increasing trace-metal flux to the global ocean. In situ measurements reveal that hydrothermally derived chromium, copper and iron bind to organic molecules on mixing with sea water. Geochemical model simulations based on data from two hydrothermal vent sites suggest that complexation significantly increases metal flux from hydrothermal systems. According to these simulations, hydrothermal fluids could account for 9% and 14% of the deep-ocean dissolved iron and copper budgets respectively. A similar role for organic complexation can be inferred for the hydrothermal fluxes of other metals, such as manganese and zinc.

  9. Rare metal-bearing pegmatites from the Southeastern Desert of Egypt: Geology, geochemical characteristics, and petrogenesis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The pegmatite province of the Southeastern Desert (SED) is part of a pegmatite district that extends from Egypt (extends to 1200 km2). Rare metal pegmatites are divided into (1) unzoned, Sn-mineralized; (2) zoned Li, Nb, Ta and Be-bearing; and (3) pegmatites and pegmatites containing colored, gem-quality tourmaline. The Rb/Sr data reflect a crustal origin for the rare metal pegmatites and indicate that the original SED magma was generated during the peak of regional metamorphism and predates the intrusion of post-tectonic leucogranites. These bodies developed an early border zone consisting of coarse to very coarse muscovite+quartz+alkali feldspar, followed by an intermediate zone of dominant quartz+feldspar+muscovite rock. Garnet, tourmaline, beryl, galena, pyrite, amblygonite, apatite and monazite are rare accessories in both zones. Cassiterite tends to concentrate in replacement zones and along fractures in albite+quartz+muscovite-rich portions. The highest concentrations of cassiterite occur in irregular greisenized zones which consist dominantly of micaceous aggregates of green Li-rich muscovite, quartz, albite and coarse-grained cassiterite. The different metasomatic post-solidification alterations include sodic and potassic metasomatism, greisenization and tourmalinization. Geochemically, the pegmatite-generating granites have a metaluminous composition, showing a differentiation trend from coarse-grained, unfractionated plagioclase-rich granite towards highly fractionated fine- to medium-grained, local albite-rich rock. Economically important ore minerals introduced by volatile-rich, rare metal-bearing fluids, either primarily or during the breakdown of the primary mineral assemblages, are niobium-tantalum oxides, Sn-oxides (cassiterite), Li-silicates (petalite, spodumene, euctyptite, and pollucite), Li-phosphates (amblygonite, montebrasite and lithopilite) and minor REE-minerals (Hf-zircon, monazite, xenotime, thorian, loparite and yttrio-fluorite). The

  10. Transient elastohydrodynamic lubrication analysis of a novel metal-on-metal hip prosthesis with a non-spherical femoral bearing surface.

    Science.gov (United States)

    Meng, Q E; Liu, F; Fisher, J; Jin, Z M

    2011-01-01

    Effective lubrication performance of metal-on-metal hip implants only requires optimum conformity within the main loaded area, while it is advantageous to increase the clearance in the equatorial region. Such a varying clearance can be achieved by using non-spherical bearing surfaces for either acetabular or femoral components. An elastohydrodynamic lubrication model of a novel metal-on-metal hip prosthesis using a non-spherical femoral bearing surface against a spherical cup was solved under loading and motion conditions specified by ISO standard. A full numerical methodology of considering the geometric variation in the rotating non-spherical head in elastohydrodynamic lubrication solution was presented, which is applicable to all non-spherical head designs. The lubrication performance of a hip prosthesis using a specific non-spherical femoral head, Alpharabola, was analysed and compared with those of spherical bearing surfaces and a non-spherical Alpharabola cup investigated in previous studies. The sensitivity of the lubrication performance to the anteversion angle of the Alpharabola head was also investigated. Results showed that the non-spherical head introduced a large squeeze-film action and also led to a large variation in clearance within the loaded area. With the same equatorial clearance, the lubrication performance of the metal-on-metal hip prosthesis using an Alpharabola head was better than that of the conventional spherical bearings but worse than that of the metal-on-metal hip prosthesis using an Alpharabola cup. The reduction in the lubrication performance caused by the initial anteversion angle of the non-spherical head was small, compared with the improvement resulted from the non-spherical geometry.

  11. On the development of a strength prediction methodology for fibre metal laminates in pin bearing

    Science.gov (United States)

    Krimbalis, Peter Panagiotis

    The development of Fibre Metal Laminates (FMLs) for application into aerospace structures represents a paradigm shift in airframe and material technology. By consolidating both monolithic metallic alloys and fibre reinforced composite layers, a new material structure is born exhibiting desired qualities emerging from its heterogeneous constituency. When mechanically fastened via pins, bolts and rivets, these laminated materials develop damage and ultimately fail via mechanisms that were not entirely understood and different than either their metallic or composite constituents. The development of a predictive methodology capable of characterizing how FMLs fastened with pins behave and fail would drastically reduce the amount of experimentation necessary for material qualification and be an invaluable design tool. The body of this thesis discusses the extension of the characteristic dimension approach to FMLs and the subsequent development of a new failure mechanism as part of a progressive damage finite element (FE) modeling methodology with yielding, delamination and buckling representing the central tenets of the new mechanism. This yielding through delamination buckling (YDB) mechanism and progressive FE model were investigated through multiple experimental studies. The experimental investigations required the development of a protocol with emphasis on measuring deformation on a local scheme in addition to a global one. With the extended protocol employed, complete characterization of the material response was possible and a new definition for yield in a pin bearing configuration was developed and subsequently extended to a tensile testing configuration. The performance of this yield definition was compared directly to existing definitions and was shown to be effective in both quasi-isotropic and orthotropic materials. The results of the experiments and FE simulations demonstrated that yielding (according to the new definition), buckling and delamination

  12. Metal Ion Selectivity of Kojate Complexes: A Theoretical Study

    Directory of Open Access Journals (Sweden)

    Sarita Singh

    2013-01-01

    Full Text Available Density functional calculations have been performed on four-coordinate kojate complexes of selected divalent metal ions in order to determine the affinity of the metal ions for the kojate ion. The complexation reactions are characterized by high energies, showing that they are highly exothermic. It is found that Ni(II exhibits the highest affinity for the kojate ion, and this is attributed to the largest amount of charge transfer from the ligand to the metal ion. The Ni(II complex has distorted square planar structure. The HOMOs and LUMOs of the complexes are also discussed. All complexes display a strong band at ~1500 cm−1 corresponding to the stretching frequency of the weakened carbonyl bond. Comparison of the complexation energies for the two steps shows that most of the complexation energy is realized in the first step. The energy released in the second step is about one-third that of the first step.

  13. METAL COMPLEXES OF HETEROCYCLIC UNSATURATED 1, 3- DIKETONES

    Directory of Open Access Journals (Sweden)

    K.L. Krishnakumar*and Mathew Paul

    2013-03-01

    Full Text Available ABSTRACT: The present investigation is mainly on the synthesis, characterization and anti-microbial screening of certain new curcuminoid analogues containing imidazole, pyrrole and thiophene rings and their metal complexes. The ability of such heterocyclic β-dicarbonyl compounds and their metal ions to influence many of complex reaction upon which the vital processes of micro-organisms depends is the motivation behind the work. A series of 5- hetero aryl-1-phenyl-4-pentene-1,3-diones(1a-c and their Cu (II, Ni (II complexes of ML2 stoichiometry were synthesized and characterized by UV, IR, mass and 1H NMR spectroscopies. Analytical and spectral data suggest neutral bidentate coordination for unsaturated diketone with metals. Anti-microbial screening was carried out by using Kirby-Bauer disc plate method. All the ligands and their metal complexes showed significant anti-microbial action. Further complexation; seem to augment the antimicrobial activity of the compounds.

  14. Hydrogen storage in complex metal hydrides

    National Research Council Canada - National Science Library

    Bogdanovic, Borislav; Felderhoff, Michael; Streukens, Guido

    2009-01-01

    ...) are solid-state hydrogen-storage materials with high hydrogen capacities. They can be used in combination with fuel cells as a hydrogen source thus enabling longer operation times compared with classical metal hydrides...

  15. Metal-Metal Interactions in Heterobimetallic Complexes with Dinucleating Redox-Active Ligands

    NARCIS (Netherlands)

    Broere, D.L.J.; Modder, D.K.; Blokker, E.; Siegler, M.A.; van der Vlugt, J.I.

    2016-01-01

    The tuning of metal-metal interactions in multinuclear assemblies is a challenge. Selective P coordination of a redox-active PNO ligand to AuI followed by homoleptic metalation of the NO pocket with NiII affords a unique trinuclear Au-Ni-Au complex. This species features two antiferromagnetically co

  16. Antitumor properties of five-coordinate gold(III) complexes bearing substituted polypyridyl ligands.

    Science.gov (United States)

    Sanghvi, Chinar D; Olsen, Pauline M; Elix, Catherine; Peng, Shifang Bruce; Wang, Dongsheng; Chen, Zhuo Georgia; Shin, Dong M; Hardcastle, Kenneth I; MacBeth, Cora E; Eichler, Jack F

    2013-11-01

    In an on-going effort to discover metallotherapeutic alternatives to the chemotherapy drug cisplatin, neutral distorted square pyramidal gold(III) coordination complexes possessing 2,9-disubstituted-1,10-phenanthroline ligands {[((R)phen)AuCl3]; R = n-butyl, sec-butyl} have been previously synthesized and characterized. A structurally analogous gold(III) complex bearing a 6,6'-di-methylbipyridine ligand ([((methyl)bipy)AuCl3]) has been synthesized and fully characterized to probe the effect of differing aromatic character of the ligand on solution stability and tumor cell cytotoxicity. The two compounds [((sec-butyl)phen)AuCl3] and [((methyl)bipy)AuCl3]) were subsequently assessed for their stability against the biological reductant glutathione, and it was found that the [((sec-butyl)phen)AuCl3] complex exhibits slightly enhanced stability compared to the [((methyl)bipy)AuCl3] complex and significantly higher stability than previously reported square planar gold(III) complex ions. Furthermore, these complexes were tested for cytotoxic effects against existing lung and head and neck cancer cell lines in vitro. The [((sec-butyl)phen)AuCl3] complex was found to be more cytotoxic than cisplatin against five different tumor cell lines, whereas [((methyl)bipy)AuCl3] had more limited in vitro antitumor activity. Given that [((sec-butyl)phen)AuCl3] had significantly higher antitumor activity, it was tested against an in vivo tumor model. It was found that this complex did not significantly reduce the growth of xenograft tumors in mice and initial model binding studies with bovine serum albumin indicate that interactions with serum albumin proteins may be the cause for the limited in vivo activity of this potential metallotherapeutic.

  17. New ruthenium nitrosyl pincer complexes bearing an O2 ligand. Mono-oxygen transfer.

    Science.gov (United States)

    Fogler, Eran; Efremenko, Irena; Gargir, Moti; Leitus, Gregory; Diskin-Posner, Yael; Ben-David, Yehoshoa; Martin, Jan M L; Milstein, David

    2015-03-02

    We report on Ru((II))(μ(2)-O2) nitrosyl pincer complexes that can return to their original Ru(0) state by reaction with mono-oxygen scavengers. Potential intermediates were calculated by density functional theory (DFT) and a mechanism is proposed, revealing a new type of metal-ligand cooperation consisting of activation of the O2 moiety by both the metal center and the NO ligand. Reaction of the Ru(0) nitrosyl complex 1 with O2 quantitatively yielded the crystallographically characterized Ru((II)) (μ(2)-O2) nitrosyl complex 2. Reaction of 2 with the mono-oxygen scavengers phosphines or CO gave the Ru(0) complex 1 and phosphine oxides, or the carbonyl complex 3 (1 trapped by CO) and CO2, respectively. Reaction of 2 with 1 equiv of phosphine at room temperature or -40 °C resulted in immediate formation of half an equivalent of 1 and 1 equiv of phosphine oxide, while half an equivalent of 2 remained unchanged. Overnight reaction at room temperature of 2 with excess CO (≥3 equiv) resulted in 3 and CO2 gas as the only products. Reaction of 1 with 1 equiv of mono-oxygen source (dioxirane) at -78 °C yielded the Ru((II))(μ(2)-O2) complex 2. Similarly, reaction of the Ru(0) dearomatized complex 4 with O2 led to the crystallographicaly characterized Ru((II))(μ(2)-O2) complex 5. Further reaction of 5 with mono-oxygen scavengers (phosphines or CO) led to the Ru(0) complex 4 and phosphine oxides or complex 6 (4 trapped by CO) and CO2. When instead only 1 equiv of 5 was reacted with 1 equiv of phosphine at room temperature, immediate formation of half an equivalent of 4 and 1 equiv of phosphine oxide took place, while half an equivalent of 5 remained unchanged. When 5 reacted with an excess of CO (≥3 equiv), complex 6 and CO2 gas were the only products obtained. DFT studies indicate a new mode of metal-ligand cooperation involving the nitrosyl ligand in the oxygen transfer process.

  18. Cadmium complexes bearing (Me2)N^E^O(-) (E = S, Se) organochalcogenoalkoxides and their zinc and mercury analogues.

    Science.gov (United States)

    Pop, Alexandra; Bellini, Clément; Şuteu, Răzvan; Dorcet, Vincent; Roisnel, Thierry; Carpentier, Jean-François; Silvestru, Anca; Sarazin, Yann

    2017-03-07

    Heteroleptic zinc and cadmium complexes of the type [{(Me2)N^E^O(R2)}M-Nu]n (M = Zn, Cd; E = S, Se; R = CH3, CF3; Nu = N(SiMe3)2, I, Cl; n = 1-2) were prepared by reacting the alcohol proteo-ligands {(Me2)N^E^O(R2)}H with [M(N(SiMe3)2)2] (M = Zn, Cd) or [XMN(SiMe3)2] (M = Zn, X = Cl; M = Cd, X = I) in an equimolar ratio. These group 12 metal complexes were characterised in solution by multinuclear NMR spectroscopy and their solid-state structures were determined by X-ray diffractometry. The ligands {(Me2)N^E^O((CH3)2)}(-) bearing CH3 groups in α position to the alkoxide behave as κ(2)-O,E-bidentate moieties (E = S, Se) and form centro-symmetric dinuclear O-bridged heteroleptic alkoxo-amido complexes both with zinc and cadmium, with four-coordinate metal centres resting in tetrahedral environments. By contrast, complexes supported by the CF3-substituted {(Me2)N^E^O((CF3)2)}(-) crystallise as tetrahedral mononuclear species, with tridentate κ(3)-N,O,E-coordinated ligands. These structural differences resulting from changes in the ligand skeleton and in the electron-donating properties of the alkoxide were also observed in solution. Attempts to prepare congeneric heteroleptic mercury complexes from [Hg(N(SiMe3)2)2] unexpectedly only afforded homoleptic bis(alkoxide)s such as [{(Me2)N^S^O((CF3)2)}2Hg]. Owing to the strong Hg-C bond, treatment of [PhHgN(SiMe3)2] with {(Me2)N^S^O((CF3)2)}H afforded the heteroleptic, T-shaped [{(Me2)N^S^O((CF3)2)}HgPh] mercuric alkoxide upon elimination of hexamethyldisilazane. [{(Me2)N^S^O((CF3)2)}2Hg] and [{(Me2)N^S^O((CF3)2)}HgPh] constitute very rare examples of structurally characterised mercuric alkoxides.

  19. N-Heterocyclic carbene metal complexes in medicinal chemistry.

    Science.gov (United States)

    Oehninger, Luciano; Rubbiani, Riccardo; Ott, Ingo

    2013-03-14

    Metal complexes with N-heterocyclic carbene (NHC) ligands are widely used in chemistry due to their catalytic properties and applied for olefin metathesis among other reactions. The enhanced application of this type of organometallics has over the last few years also triggered a steadily increasing number of studies in the fields of medicinal chemistry, which take advantage of the fascinating chemical properties of these complexes. In fact it has been demonstrated that metal NHC complexes can be used to develop highly efficient metal based drugs with possible applications in the treatment of cancer or infectious diseases. Complexes of silver and gold have been biologically evaluated most frequently but also platinum or other transition metals have demonstrated promising biological properties.

  20. studies on transition metal complexes of herbicidal compounds. ii

    African Journals Online (AJOL)

    a

    II: TRANSITION METAL COMPLEXES OF DERIVATIZED 2-CHLORO-4- ... Several compounds of this class like atrazine, simazine, prometryn, aziprotryn, etc. .... dissolve in water and most of the common polar organic solvents. ... coordination.

  1. Bioactive luminescent transition-metal complexes for biomedical applications.

    Science.gov (United States)

    Ma, Dik-Lung; He, Hong-Zhang; Leung, Ka-Ho; Chan, Daniel Shiu-Hin; Leung, Chung-Hang

    2013-07-22

    The serendipitous discovery of the anticancer drug cisplatin cemented medicinal inorganic chemistry as an independent discipline in the 1960s. Luminescent metal complexes have subsequently been widely applied for sensing, bio-imaging, and in organic light-emitting diode applications. Transition-metal complexes possess a variety of advantages that make them suitable as therapeutics and as luminescent probes for biomolecules. It is thus highly desirable to develop new luminescent metal complexes that either interact with DNA through different binding modes or target alternative cellular machinery such as proteins as well as to provide a more effective means of monitoring disease progression. In this Review, we highlight recent examples of biologically active luminescent metal complexes that can target and probe a specific biomolecule, and offer insights into the future potential of these compounds for the investigation and treatment of human diseases.

  2. Metal-ligand bifunctional reactivity and catalysis of protic N-heterocyclic carbene and pyrazole complexes featuring β-NH units.

    Science.gov (United States)

    Kuwata, Shigeki; Ikariya, Takao

    2014-11-28

    Metal-ligand bifunctional cooperation has attracted much attention because it offers a powerful methodology to realize a number of highly efficient and selective catalysts. In this article, recent developments in the metal-ligand cooperative reactions of protic N-heterocyclic carbene (NHC) and pyrazole complexes bearing an acidic NH group at the position β to the metal are surveyed. Protic 2-pyridylidenes as related cooperating non-innocent ligands are also described.

  3. Inkjet Printing of 3D Metallic Silver Complex Microstructures

    NARCIS (Netherlands)

    Wits, Wessel Willems; Sridhar, Ashok; Dimitrov, D.

    2010-01-01

    To broaden the scope of inkjet printing, this paper focuses on printing of an organic silver complex ink on glass substrates towards the fabrication of metallic 3D microstructures. The droplet formation sequence of the inkjet printer is optimised to print continuous layers of metal. A brief discussi

  4. Inkjet Printing of 3D Metallic Silver Complex Microstructures

    NARCIS (Netherlands)

    Wits, Wessel Willems; Sridhar, Ashok; Dimitrov, D.

    2010-01-01

    To broaden the scope of inkjet printing, this paper focuses on printing of an organic silver complex ink on glass substrates towards the fabrication of metallic 3D microstructures. The droplet formation sequence of the inkjet printer is optimised to print continuous layers of metal. A brief

  5. Inkjet printing of 3D metallic silver complex microstructures

    NARCIS (Netherlands)

    Wits, Wessel W.; Sridhar, Ashok

    2010-01-01

    To broaden the scope of inkjet printing, this paper focuses on printing of an organic silver complex ink on glass substrates towards the fabrication of metallic 3D microstructures. The droplet formation sequence of the inkjet printer is optimised to print continuous layers of metal. A brief discussi

  6. Revisited: the conception of lability of metal complexes

    NARCIS (Netherlands)

    Leeuwen, van H.P.

    2001-01-01

    Starting from the original reaction layer concept, the voltammetric properties of electroinactive metal complexes are critically reviewed in terms of their finite rates of dissociation into electroactive free metal ions. The limiting conditions for the reaction layer-based flux expressions are made

  7. Compartmentation and complexation of metals in hyperaccumulator plants.

    Science.gov (United States)

    Leitenmaier, Barbara; Küpper, Hendrik

    2013-09-20

    Hyperaccumulators are being intensely investigated. They are not only interesting in scientific context due to their "strange" behavior in terms of dealing with high concentrations of metals, but also because of their use in phytoremediation and phytomining, for which understanding the mechanisms of hyperaccumulation is crucial. Hyperaccumulators naturally use metal accumulation as a defense against herbivores and pathogens, and therefore deal with accumulated metals in very specific ways of complexation and compartmentation, different from non-hyperaccumulator plants and also non-hyperaccumulated metals. For example, in contrast to non-hyperaccumulators, in hyperaccumulators even the classical phytochelatin-inducing metal, cadmium, is predominantly not bound by such sulfur ligands, but only by weak oxygen ligands. This applies to all hyperaccumulated metals investigated so far, as well as hyperaccumulation of the metalloid arsenic. Stronger ligands, as they have been shown to complex metals in non-hyperaccumulators, are in hyperaccumulators used for transient binding during transport to the storage sites (e.g., nicotianamine) and possibly for export of Cu in Cd/Zn hyperaccumulators [metallothioneins (MTs)]. This confirmed that enhanced active metal transport, and not metal complexation, is the key mechanism of hyperaccumulation. Hyperaccumulators tolerate the high amount of accumulated heavy metals by sequestering them into vacuoles, usually in large storage cells of the epidermis. This is mediated by strongly elevated expression of specific transport proteins in various tissues from metal uptake in the shoots up to the storage sites in the leaf epidermis. However, this mechanism seems to be very metal specific. Non-hyperaccumulated metals in hyperaccumulators seem to be dealt with like in non-hyperaccumulator plants, i.e., detoxified by binding to strong ligands such as MTs.

  8. Compartmentation and complexation of metals in hyperaccumulator plants

    Directory of Open Access Journals (Sweden)

    Barbara eLeitenmaier

    2013-09-01

    Full Text Available Hyperaccumulators are being intensely investigated. They are not only interesting in scientific context due to their strange behaviour in terms of dealing with high concentrations of metals, but also because of their use in phytoremediation and phytomining, for which understanding the mechanisms of hyperaccumulation is crucial. Hyperaccumulators naturally use metal accumulation as a defence against herbivores and pathogens, and therefore deal with accumulated metals in very specific ways of complexation and compartmentation, different from non-hyperaccumulator plants and also non-hyperaccumulated metals. For example, in contrast to non-hyperaccumulators, in hyperaccumulators even the classical phytochelatin-inducing metal, cadmium, is predominantly not bound by such sulfur ligands, but only by weak oxygen ligands. This applies to all hyperaccumulated metals investigated so far, as well as hyperaccumulation of the metalloid arsenic. Stronger ligands, as they have been shown to complex metals in non-hyperaccumulators, are in hyperaccumulators used for transient binding during transport to the storage sites. This confirmed that enhanced active metal transport, and not metal complexation, is the key mechanism of hyperaccumulation. Hyperaccumulators tolerate the high amount of accumulated heavy metals by sequestering them into vacuoles, usually in large storage cells of the epidermis. This is mediated by strongly elevated expression of specific transport proteins in various tissues from metal uptake in the shoots up to the storage sites in the leaf epidermis. However, this mechanism seems to be very metal specific. Non-hyperaccumulated metals in hyperaccumulators seem to be dealt with like in non-hyperaccumulator plants, i.e. detoxified by binding to strong ligands such as metallothioneins.

  9. Therapeutic treatment of Alzheimer's disease using metal complexing agents.

    Science.gov (United States)

    Price, Katherine A; Crouch, Peter J; White, Anthony R

    2007-11-01

    Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by deposition of extracellular amyloid plaques, formation of intracellular neurofibrillary tangles and neuronal dysfunction in the brain. A growing body of evidence indicates a central role for biometals such as copper in many critical aspects of AD. The amyloid beta (Abeta) peptide and its parental molecule, the amyloid precursor protein (APP) both modulate Cu and Zn metabolism in the brain. Therefore, aberrant changes to APP or Abeta metabolism could potentially alter biometal homoestasis in AD, leading to increased free radical production and neuronal oxidative stress. Modulation of metal bioavailability in the brain has been proposed as a potential therapeutic strategy for treatment of AD patients. The lipid permeable metal complexing agent, clioquinol (CQ), has shown promising results in animal models of AD and in small clinical trials involving AD patients. Moreover, a new generation of metal-ligand based therapeutics is currently under development. Patents now cover the generation of novel metal ligand structures designed to modulate metal binding to Abeta and quench metal-mediated free radical generation. However, the mechanism by which CQ and other metal complexing agents slows cognitive decline in AD animal models and patients is unknown. Increasing evidence suggests that ligand-mediated redistribution of metals at a cellular level in the brain may be important. Further research will be necessary to fully understand the complex pathways associated with efficacious metal-based pharmaceuticals for treatment of AD.

  10. Heavy metal music meets complexity and sustainability science.

    Science.gov (United States)

    Angeler, David G

    2016-01-01

    This paper builds a bridge between heavy metal music, complexity theory and sustainability science to show the potential of the (auditory) arts to inform different aspects of complex systems of people and nature. The links are described along different dimensions. This first dimension focuses on the scientific aspect of heavy metal. It uses complex adaptive systems theory to show that the rapid diversification and evolution of heavy metal into multiple subgenres leads to a self-organizing and resilient socio-musicological system. The second dimension builds on the recent use of heavy metal as a critical thinking model and educational tool, emphasizing the artistic component of heavy metal and its potential to increase people's awareness of environmental sustainability challenges. The relationships between metal, complexity theory and sustainability are first discussed independently to specifically show mechanistic links and the reciprocal potential to inform one domain (science) by the other (metal) within these dimensions. The paper concludes by highlighting that these dimensions entrain each other within a broader social-cultural-environmental system that cannot be explained simply by the sum of independent, individual dimensions. Such a unified view embraces the inherent complexity with which systems of people and nature interact. These lines of exploration suggest that the arts and the sciences form a logical partnership. Such a partnership might help in endeavors to envision, understand and cope with the broad ramifications of sustainability challenges in times of rapid social, cultural, and environmental change.

  11. Complexation and Antimicrobial Studies of Some Divalent Metal Chelates

    Directory of Open Access Journals (Sweden)

    Suparna Ghosh

    2010-01-01

    Full Text Available Metal chelates of Ni(II and Cu(II with the ligand 5-acetamido-1,3,4-thiadiazole-2-sulphonamide have been synthesized. The isolated compounds have been characterized by elemental analysis, molar conductivity, magnetic moment, electronic and IR spectral studies. The analytical data reflects the metal to ligand stoichiometry to be 1: 2. The conductivity data of the complexes also suggests their non-electrolytic nature. The stability constants and free energy change for the complexes have been calculated.. Ligand and their complexes have been screened for their biological activity and the data show good activity of these complexes and ligands.

  12. Lability of nanoparticulate metal complexes in electrochemical speciation analysis

    DEFF Research Database (Denmark)

    van Leeuwen, Herman P.; Town, Raewyn M.

    2016-01-01

    Lability concepts are elaborated for metal complexes with soft (3D) and hard (2D) aqueous nanoparticles. In the presence of a non-equilibrium sensor, e.g. a voltammetric electrode, the notion of lability for nanoparticulate metal complexes, M-NP, reflects the ability of the M-NP to maintain...... develop at the particle/medium interface. Thus the chemodynamic features of M-NP complexes should be fundamentally different from those of molecular systems in which the reaction layer is a property of the homogeneous solution (μ = (DM/ka ′)1/2). For molecular complexes, the characteristic timescale...

  13. Synthesis, characterization and biological profile of metal and azo-metal complexes of embelin

    Directory of Open Access Journals (Sweden)

    R. Aravindhan

    2014-12-01

    Full Text Available The present study emphasizes synthesis and bioprofiling of embelin, embelin-metal (EM and embelin-azo-metal (EAM complexes in detail. EM complexes were prepared using pure embelin and d-block transition elements, namely Mn, Fe, Co, Ni, Cu, and Zn. Similarly, EAM complexes were synthesized using phenyl azo-embelin with the said transition metals. Embelin, EM, and EAM complexes were subjected to ultra violet visible spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance, electrospray ionization mass spectrometry, thermogravimetric analysis, carbon hydrogen nitrogen sulfur analysis. With regard to bioprofiling, the test complexes were studied for the antioxidant and antimicrobial activities. Results revealed that the prepared EM and EAM complexes form octahedral complexes with embelin with the yield in the range of 45–75%. All the instrumental analyses authenticate the interaction of metals with bidentate embelin through its enolic and quinonic oxygen atoms as [M(Emb2(H2O2]H2O and [M(Emb-Azo2(H2O2]. The antioxidant profile studies suggested that upon complexation with metals, the free radical scavenging activity of embelin reduced significantly. But, with regard to antimicrobial activity, cobalt and nickel embelin complexes displayed>80% growth inhibition in comparison with embelin alone. The hemolytic activity studies suggested that both embelin and the metal complexes are non-hemolytic. The reason for the reduction in antioxidant and an increase in antimicrobial activities were discussed in detail.

  14. The path for metal complexes to a DNA target.

    Science.gov (United States)

    Komor, Alexis C; Barton, Jacqueline K

    2013-05-01

    The discovery of cisplatin as a therapeutic agent stimulated a new era in the application of transition metal complexes for therapeutic design. Here we describe recent results on a variety of transition metal complexes targeted to DNA to illustrate many of the issues involved in new therapeutic design. We describe first structural studies of complexes bound covalently and non-covalently to DNA to identify potential lesions within the cell. We then review the biological fates of these complexes, illustrating the key elements in obtaining potent activity, the importance of uptake and subcellular localization of the complexes, as well as the techniques used to delineate these characteristics. Genomic DNA provides a challenging but valuable target for new transition metal-based therapeutics.

  15. Carbon Solubility in Silicon-Iron-Bearing Metals during Core Formation on Mercury

    Science.gov (United States)

    Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Ross, D. Kent; Rapp, Jennifer F.; Danielson, Lisa R.; Keller, Lindsay P.; Righter, Kevin

    2016-01-01

    potential light element that could be incorporated into Mercury's core. The goal of this study is to determine the carbon concentration at graphite saturation in various silicon-iron bearing metals relevant to possible mercurian core compositions. Future experiments will include the addition of sulfur into these metals.

  16. Microstructure of N—Picolylpolyurethane Transition Metal Complexes

    Institute of Scientific and Technical Information of China (English)

    Qun-DongShen; Tian-DouHu; 等

    1999-01-01

    Spectroscopic methods are used to investigate coordination structure of N-picolylpolyurethane transition metal complexes(PUPYM,M=Co2+ and Ni2+) .Geometrical arrangement of ligands in first-shell coordination sphere of metal ions is postulated to be tetrahedral CoL2Cl2 and octahedral NiL2-Cl2Z2.where L is the picolyl group and Z is a hydrate.From extended X-ray absorption fine structure (EXAFS) analysis,bond lengths for metal-chlorine and metal-ligand of PUPYM are similar to those of small molecular weight transition metal complexes.A two-phase model of PUPYM which best describes the experimental data of DMTA and SAXS.is proposed.One microphase is the hard domain of self segregated haed segments brought about by metal-ligand interaction.and the other phase is the matrix of soft segments.Transition metal ion-ligand moieties and their interactions dominate the macroscopic thermal behavior of PUPYM.The ligand field stabilization energy difference(ΔLFSE) between mteal d-electrons in complexes with two picolyl ligands in the coordination sphere of metal ions and complexes maintaining one picolyl ligand as coordination pendent group is calculated on the basis of observed coordination structure,and it represents the energy supplied to split coordination cross-links.ΔLFSE of polyurethane nickel(II) complex is larger than that of the cobalt(II) complex,Since the mobility of hard segments is in inverse proportion to the strength of coordination cross-links.a higher α-transition temperature of PUPYNi2+ with respect to PUPYCo2+ is found as expected.

  17. A new metalation complex for organic synthesis and polymerization reactions

    Science.gov (United States)

    Hirshfield, S. M.

    1971-01-01

    Organometallic complex of N,N,N',N' tetramethyl ethylene diamine /TMEDA/ and lithium acts as metalation intermediate for controlled systhesis of aromatic organic compounds and polymer formation. Complex of TMEDA and lithium aids in preparation of various organic lithium compounds.

  18. Transition metal complexes with Girard reagents and their hydrazones

    Directory of Open Access Journals (Sweden)

    Vojinović-Ješić Ljiljana S.

    2012-01-01

    Full Text Available This is the first review dealing with the coordination chemistry of metal complexes with Girard's reagents and their hydrazones. The short introduction points out to chemical properties and significance of these organic compounds. The next section briefly describes synthetic methods for preparing complexes with Girard's reagents, as well as modes of coordination of these ligands. The last two extensive sections review the preparation, stereochemistry and structural characteristics of metal complexes with Girard's hydrazones, including some newer non-hydrazonic derivatives of Girard's reagents, also.[Acknowledgments. Projekat Ministarstva nauke Republike Srbije, br. 172014

  19. Bioinspired catalysis metal-sulfur complexes

    CERN Document Server

    Weigand, Wolfgang

    2014-01-01

    The growing interest in green chemistry calls for new, efficient and cheap catalysts. Living organisms contain a wide range of remarkably powerful enzymes, which can be imitated by chemists in the search for new catalysts. In bioinspired catalysis, chemists use the basic principles of biological enzymes when creating new catalyst analogues. In this book, an international group of experts cover the topic from theoretical aspects to applications by including a wide variety of examples of different systems. This valuable overview of bioinspired metal-sulfur catalysis is a must-have for all sci

  20. Metal plasmon enhanced europium complex luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Liu Feng [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario, K7L 3N6 (Canada); Aldea, Gabriela [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario, K7L 3N6 (Canada); Petru Poni Institute of Macromolecular Chemistry Iasi, Aleea Grigore Ghica Voda 41A, 700487 Iasi (Romania); Nunzi, Jean-Michel, E-mail: nunzijm@queensu.c [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario, K7L 3N6 (Canada)

    2010-01-15

    The plasmon enhanced luminescence of a rare-earth complex Tris(6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato) europium (Eu(fod){sub 3}) was investigated. A polyvinyl alcohol (PVA) thin film was successfully adopted as a spacer to separate the Eu complex from the silver island film (SIF), and five-fold enhancement of the radiative decay rate of the Eu complex on SIF was demonstrated based on the luminescence intensity and lifetime measurement. Investigation of the distance dependent luminescence indicates that 7 nm is an optimal distance for SIF enhanced Eu luminescence. Plasmon enhanced rare-earth luminescence based on an organic film spacer would find potential applications in plasmon enhanced organic light emitting diode (OLED) devices.

  1. Photodissociation Studies of Metal-Containing Clusters and Complexes

    Science.gov (United States)

    Pilgrim, Jeffrey Scott

    1995-01-01

    There have been two major areas of investigation for researchers working with laser ablation in molecular beams. The first area is the study of weakly-bound complexes. These complexes are bound by electrostatic interactions. In the present study the weakly bound interactions of the rare gases with the magnesium ion are investigated with electronic spectroscopy. The second major area is the study of metal and metal-containing clusters. Examples of previous investigations are the alkali metal clusters and the fullerenes. The present investigation is on metal -carbon clusters. The so-called metallo-carbohedrenes and metal-carbon nanocrystals are studied. Resonance enhanced photodissociation spectroscopy is used to obtain electronic excitation spectra of the Mg^+-rare gas species in the ultraviolet region. This investigation is facilitated by a reflectron time-of-flight mass spectrometer. The interaction of the rare gas with the metal ion is attributed to a "solvation" of the atomic ion transition. Simple bonding arguments predict that the excited state is more bound than the ground state for these complexes. This will result in a shift of the complex vibronic origin to lower energy from the atomic ion transition. This is exactly what is observed in the experiment with progressively larger shifts for the heavier rare gases. The electronic excitation spectra allow the vibrational frequencies and anharmonicities for these complexes to be obtained for the excited state. In turn, the excited state bond dissociation energies can be determined. Finally, conservation of energy allows calculation of the ground state bond dissociation energies. In the metal-carbon systems the stability of the metallo-carbohedrene, met-car, stoichiometry is shown to extend into the transition period at least to the iron group. Photodissociation with a 532 nm laser causes a loss of metal atoms for met-cars formed with first row transition metals and a loss of metal-carbon units for met

  2. Effect of femoral head size on the wear of metal on metal bearings in total hip replacements under adverse edge-loading conditions.

    Science.gov (United States)

    Al-Hajjar, Mazen; Fisher, John; Williams, Sophie; Tipper, Joanne L; Jennings, Louise M

    2013-02-01

    Metal-on-metal (MoM) bearings have shown low-wear rates under standard hip simulator conditions; however, retrieval studies have shown large variations in wear rates and mechanisms. High-wear in vivo has caused catastrophic complications and has been associated with steep cup-inclination angle (rotational malpositioning). However, increasing the cup-inclination angle in vitro has not replicated the increases in wear to the same extent as those observed in retrievals. Clinically relevant wear rates, patterns, and particles were observed in vitro for ceramic-on-ceramic bearings when microseparation (translational malpositioning) conditions were introduced into the gait cycle. In the present study, 28 and 36-mm MoM bearings were investigated under adverse conditions. Increasing the cup angle from 45° to 65° resulted in a significant increase in the wear rate of the 28 mm bearings. However, for the 36 mm bearings, head-rim contact did not occur under the steep cup-angle condition, and the wear rate did not increase. The introduction of microseparation to the gait cycle significantly increased the wear rate of the MoM bearings. Cup angle and head size did not influence the wear rate under microseparation conditions. This study indicated that high-in vivo wear rates were associated with edge loading due to rotational malpositioning such as high-cup-inclination angle and translational malpositioning that could occur due to several surgical factors. Translational malpositioning had a more dominant effect on the wear rate. Preclinical simulation testing should be undertaken with translational and rotational malpositioning conditions as well as standard walking cycle conditions defined by the ISO standard. Copyright © 2012 Wiley Periodicals, Inc.

  3. Dipicolinate complexes of main group metals with hydrazinium cation

    Indian Academy of Sciences (India)

    K Saravanan; S Govindarajan

    2002-02-01

    Some new coordination complexes of hydrazinium main group metal dipicolinate hydrates of formulae (N2H5)2M(dip)2.H2O (where, M =Ca, Sr, Ba or Pb and = 0, 2, 4 and 3 respectively and dip = dipicolinate), N2H5Bi(dip)2.3H2O and (N2H5)3Bi(dip)3.4H2O have been prepared and characterized by physico-chemical techniques. The infrared spectra of the complexes reveal the presence of tridentate dipicolinate dianions and non-coordinating hydrazinium cations. Conductance measurements show that the mono, di and trihydrazinium complexes behave as 1:1, 2:1 and 3:1 electrolytes respectively, in aqueous solution. Thermal decomposition studies show that these compounds lose water followed by endothermic decomposition of hydrazine to give respective metal hydrogendipicolinate intermediates, which further decompose exothermically to the final product of either metal carbonates (Ca, Sr, Ba and Pb) or metal oxycarbonates (Bi). The coordination numbers around the metal ions differ from compound to compound. The various coordination numbers exhibited by these metals are six (Ca), seven (Ba), eight (Sr) and nine (Pb and Bi). In all the complexes the above coordination number is attained by tridentate dipicolinate dianions and water molecules. The X-ray diffraction patterns of these compounds differ from one another suggesting that they are not isomorphous.

  4. Luminescent Pt(II) complexes bearing dual isoquinolinyl pyrazolates: fundamentals and applications.

    Science.gov (United States)

    Ku, Hsiao-Yun; Tong, Bihai; Chi, Yun; Kao, Hao-Che; Yeh, Chia-Chi; Chang, Chih-Hao; Lee, Gene-Hsiang

    2015-05-14

    A series of four Pt(II) metal complexes with trans-arranged isoquinolinyl azolates have been prepared, [Pt(Lx)2], x = 1-4, (1-4). The associated chelates possess various substituents; namely: one t-butyl (Bu(t)) at the 6-position (L1), two Bu(t) groups at the 5,7-positions (L2), one dip (2,6-di-isopropylphenyl) group at the 6-position (L3), and a single dip group at the 4-position of the 1-isoquinolinyl fragment (L4), respectively. Crystal structures of 1 and 4 were determined to shed light on the relationship of photophysics and packing arrangements. Their photophysical properties were measured and compared, for which the solid-state emission spectra of 2 and 4 are nearly identical to the solution spectra of all the Pt(II) complexes, showing the formation of isolated molecular entities. In contrast, the Pt(II) complexes 1 and 3 are found to be sensitive to their morphological states and external stimulus. This is confirmed by the gradual red-shifting of the emission with increasing concentration in the PMMA matrix, and the eventual formation of the broadened, metal-metal-to-ligand charge transfer (MMLCT) emission, by (i) wetting with acetone and drying in air, or (ii) grinding with a mortar and pestle, respectively. Organic light-emitting diodes (OLEDs) were also fabricated using multiple layered architecture and lowered doping concentration (e.g. 8 wt%), the latter is for avoiding dopant aggregation in the emitting layer. The associated OLED performances (i.e. η(max) = 11.5%, 8.5%, and 11.2% for 1, 2 and 3) confirmed their suitability and potential as dopants for phosphorescent OLEDs.

  5. Effect of atmospheric organic complexation on iron-bearing dust solubility

    Directory of Open Access Journals (Sweden)

    R. Paris

    2013-05-01

    Full Text Available Recent studies reported that the effect of organic complexation may be a potentially important process to be considered by models estimating atmospheric iron flux to the ocean. In this study, we investigated this process effect by a series of dissolution experiments on iron-bearing dust in the presence or the absence of various organic compounds (acetate, formate, oxalate, malonate, succinate, glutarate, glycolate, lactate, tartrate and humic acid as an analogue of humic like substances, HULIS typically found in atmospheric waters. Only 4 of tested organic ligands (oxalate, malonate, tartrate and humic acid caused an enhancement of iron solubility which was associated with an increase of dissolved Fe(II concentrations. For all of these organic ligands, a positive linear dependence of iron solubility to organic concentrations was observed and showed that the extent of organic complexation on iron solubility decreased in the following order: oxalate >malonate = tartrate > humic acid. This was attributed to the ability of electron donors of organic ligands and implies a reductive ligand-promoted dissolution. This study confirms that among the known atmospheric organic binding ligands of Fe, oxalate is the most effective ligand promoting dust iron solubility and showed, for the first time, the potential effect of HULIS on iron dissolution under atmospheric conditions.

  6. A Cancer Stem Cell Potent Cobalt(III–Cyclam Complex Bearing Two Tolfenamic Acid Moieties

    Directory of Open Access Journals (Sweden)

    Paul B. Cressey

    2017-02-01

    Full Text Available Cancer stem cells (CSCs are thought to be responsible for cancer relapse. CSCs are a subtype of cancer cells with the ability to differentiate, self-renew, and form secondary or tertiary tumors. Current cancer treatments—including chemotherapy, radiation, and surgery—effectively remove bulk cancer cells but are unable to eliminate CSCs. Here, we present the synthesis, characterization, and anti-CSC properties of a cobalt(III–cyclam complex bearing two tolfenamic acid moieties, 3. Notably, 3 displays sub-micromolar potency towards breast CSCs and bulk breast cancer cells. Detailed mechanistic studies show that 3 is taken up readily by breast CSCs, enters the nucleus, causes DNA damage, and induces caspase-dependent apoptosis. Furthermore, 3 inhibits cyclooxygenase-2 (COX-2 expression in CSCs. The mechanism of action of 3 is similar to that of a naproxen-appended cobalt(III–cyclam complex, 1 recently reported by our group. The advantage of 3 over 1 is that it has the potential to remove whole tumor populations (bulk cancer cells and CSCs with a single dose.

  7. Preparation and Characterization of Double Metal Cyanide Complex Catalysts

    Directory of Open Access Journals (Sweden)

    Weilin Guo

    2003-01-01

    Full Text Available A series of double metal cyanide (DMC complex catalysts were prepared in two different methods by using ß-cyclodextrin, PEG-1000 and Tween-60 as an additional complex ligands respectively. It was showed that a mixture of crystalline and amorphous DMC was synthesized by using traditional method in which the additional complex ligand was added after the precipitation of DMC. Amorphous and dispersed DMC with higher activity could be obtained when the additional complex ligand was added in the reactant solution before reaction. The effect of additional complex ligand and preparation method on the crystalline state and catalytic property of DMC were also investigated.

  8. Precious metal-bearing epithermal deposits in western Patagonia (NE Lago Fontana region), Argentina

    Science.gov (United States)

    Lanfranchini, Mabel Elena; Etcheverry, Ricardo Oscar; de Barrio, Raúl Ernesto; Recio Hernández, Clemente

    2013-04-01

    Precious metal-bearing quartz veins occur at the northeastern sector of the Lago Fontana region in southwestern Argentina, within the context of the Andean continental magmatic arc environment. The deposits and their associated alteration zones are spatially related to a Cretaceous calc-alkaline magmatism represented by silicic dikes and hypabyssal intrusions, and hosted by a Late Jurassic to Cretaceous volcano-sedimentary sequence. The veins and related veinlets crop out discontinuously, in general terms in a NW-SE belt. The primary vein mineral assemblage is composed mostly of pyrite ± galena ± chalcopyrite > hematite ± arsenopyrite in silica gangue minerals. Chemical analyses of grab samples from selected quartz veins show as much as 5.7 ppm Au and 224 ppm Ag, as well as elevated Pb, Cu, and Zn. Hydrothermal fluids caused an innermost silicification and adularia-sericite alteration assemblage, and an external propylitic halo. Sulfur isotope values measured for sulfides (δSS from -1.90 to +1.56‰), and oxygen and hydrogen isotopes measured on quartz crystals and extracted primary fluid inclusion waters (δOO = -2.85 to +5.40‰; δDO = -106.0 to -103.4‰) indicate that mineralization probably formed from magmatic fluids, which were mixed with meteoric waters. Also, fluid inclusion data from quartz veins point out that these fluids had low salinity (1.7-4.2 wt% NaCl equiv.), and temperatures of homogenization between 180 and 325 °C. Mineralogical, petrographic and geochemical features for mineralized surface exposures indicate a typical adularia-sericite, low sulfidation epithermal system in the Lago Fontana area that represents a promising target for further exploration programs.

  9. Bovine Serum Albumin Metal Complexes for Mimic of SOD

    Indian Academy of Sciences (India)

    GUIFANG YAN; YUFENG HE; GANG LI; YUBING XIONG; PENGFEI SONG; RONG-MIN WANG

    2016-11-01

    Superoxide anion radical (O•−₂ ) is a noxious reactive oxygen species (ROS). Transition metal ion complexes have been generally used as antioxidants to eliminate ROS. In this work, a neoteric watersoluble biopolymer metal complex (BSA-M) was prepared by conjugating the soluble biopolymer bovineserum albumin (BSA) with three transition metal ions (M, M=Cu, Co, Mn). The binding mode and ratio of metal ions bound to albumin were investigated. The BSA-M complexes were characterized by UV-Vis, circular dichroism (CD) spectra and polyacrylamide gel electrophoresis (PAGE). BSA served as polymerscaffold and the metal complex functioned as the catalytic active center. The results demonstrated that the structure of BSA remained unchanged when the binding ratio of transition metal ion complex to BSA was 5:1. Furthermore, the scavenging superoxide anion free radical (O•−₂ ) activity of biopolymer-metal complexes were determined by nitroblue tetrazolium light reduction assay method. The antioxidant capacity of BSA-M has markedly increased. The conjugated BSA-M (M=Cu, Mn) showed preeminent scavenging activity for O•−₂ , and the EC₅₀ value of the BSA-Cu was 0.038±0.0013μmol·L⁻¹, which is comparable to EC₅₀ value (0.041±0.001μmol·L⁻¹) of the natural superoxide dismutase (SOD), the analog quantity reached 107%. As a consequence, it can be considered as a bio-functional mimic of enzyme SOD and has a promising application prospect in antioxidant drug field.

  10. Electric relaxation processes in chemodynamics of aqueous metal complexes: From simple ligands to soft nanoparticulate complexants

    NARCIS (Netherlands)

    Leeuwen, van H.P.; Buffle, J.; Town, R.M.

    2012-01-01

    The chemodynamics of metal complexes with nanoparticulate complexants can differ significantly from that for simple ligands. The spatial confinement of charged sites and binding sites to the nanoparticulate body impacts on the time scales of various steps in the overall complex formation process.

  11. Synthesis, Structure and Luminescent Properties of Polymeric Copper(Ⅰ) Halide Complexes Bearing Phosphine and N-donor Bridging Ligands

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Three polymeric copper(Ⅰ) halide complexes bearing phosphine and N-donor bridging ligands, [(PPh3)2Cu2(μ-Br)2(μ-4,4'-bipy)]∞ 1 (bipy=bipyridine), [(PPh3)2Cu2(μ-Br)2(μ-bpe)]∞ 2 (bpe=trans-1,2-bis(4-pyridyl)ethene) and [(PPh3)2Cu2(μ-Cl)2(μ-bpe)]∞ 3, were synthesized by the multilayer diffusion method, and the structures were refined by single-crystal X-ray diffraction. Complex 1 crystallizes in triclinic, space group P-1 with a=9.122(3), b=9.322(3), c=13.201(4) (A),α=106.440(4), β=105.965(5), γ=94.167(5)°, V=1021.3(6) (A), Mr=967.62, Z=1,Dc=1.573 g/cm3, F(000)=486,μ=3.111 mm-1, the final R=0.0383 and wR=0.0960 for 2792observed reflections (I > 2σ(Ⅰ)). Complex 2 crystallizes in triclinic, space group P-1 with a=9.420(3), b=10.209(4), c=12.407(4)(A), α=104.136(6), β=108.132(5), γ=95.338(6)°, V=1081.0(7)(A), Mr=496.83, Z=2, Dc=1.526 g/cm3, F(000)=500,μ=2.941 mm-1, the final R=0.0445 and wR=0.1117 for 3251 observed reflections (I> 2σ(Ⅰ)). Complex 3 crystallizes in triclinic,space group P-1 with a=8.32(1), b=11.53(2), c=13.94(3)(A), α=109.57(3), β=93.85(3), γ=97.28(3)°, V=1242(4)(A)3, Mr=1074.59, Z=1, Dc=1.436 g/cm3, F(000)=548,μ=1.279 mm-1,the final R=0.0786 and wR=0.1586 for 2266 observed reflections (I > 2σ(Ⅰ)). The complexes exhibit intensive solid-state photoluminescence tentatively assigned to an admixture of triplet intraligand (IL) and metal-to-ligand charge-transfer (MLCT) excited state.

  12. Treatment of metal-containing wastewater by adsorption of metal-chelate complexes onto activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Shay, M.A.

    1989-01-01

    To eliminate difficulties associated with interference of chelating or complexing agents on precipitation of heavy metals from wastewaters, the feasibility of a process which utilized chelating agents in the removal of the heavy metals was investigated. Heavy metal ions were removed from simulated metal plating wastewater by sorption of a heavy metal chelate complex onto activated carbon. In this process, a chelate which might be present in a wastewater could be used in removal of a heavy metal, rather than interfere with its removal. System development of a continuous flow process consisted of bench scale column tests to answer questions about key adsorption column operating parameters. The metals investigated were Cu(II), Ni(II) and Zn(II). Hydrogen ion concentration had the largest effect on removal of heavy metalchelate complexes, but contact time and heavy metal:chelate ratio were important. The normal contact time for activated carbon columns of 30 to 60 minutes was found adequate to achieve heavy metal-chelate removals of at least 90% for citrate or EDTA complexes. For citrate complexes better removals were achieved at heavy metal:chelate ratios greater than 1:1. For EDTA, there was no advantage to ratios greater than 1:1. Increasing pH, at least to pH 9.0, increased the heavy metal chelate removal; however, for EDTA, removals greater than 90% could be achieved at a pH as low as 3.0. The maximum amount of Cu(II)-citrate complex that could be removed was 2.8 mg per gram of carbon, the maximum amount for Zn(II)citrate complex was 1.2 mg per gram of carbon, and for Ni(II)-citrate, the maximum was 1.3 mg per gram of carbon. For the EDTA complexes, the maximum removal was 2.1 mg of Cu(II)-EDTA complex per gram of carbon, 6.9 mg of Zn(II)-EDTA complex per gram of carbon, and 3.2 mg of Ni(II)-EDTA complex per gram of carbon.

  13. Double-dictionary matching pursuit for fault extent evaluation of rolling bearing based on the Lempel-Ziv complexity

    Science.gov (United States)

    Cui, Lingli; Gong, Xiangyang; Zhang, Jianyu; Wang, Huaqing

    2016-12-01

    The quantitative diagnosis of rolling bearing fault severity is particularly crucial to realize a proper maintenance decision. Aiming at the fault feature of rolling bearing, a novel double-dictionary matching pursuit (DDMP) for fault extent evaluation of rolling bearing based on the Lempel-Ziv complexity (LZC) index is proposed in this paper. In order to match the features of rolling bearing fault, the impulse time-frequency dictionary and modulation dictionary are constructed to form the double-dictionary by using the method of parameterized function model. Then a novel matching pursuit method is proposed based on the new double-dictionary. For rolling bearing vibration signals with different fault sizes, the signals are decomposed and reconstructed by the DDMP. After the noise reduced and signals reconstructed, the LZC index is introduced to realize the fault extent evaluation. The applications of this method to the fault experimental signals of bearing outer race and inner race with different degree of injury have shown that the proposed method can effectively realize the fault extent evaluation.

  14. Metal Complexes of EDTA: An Exercise in Data Interpretation

    Science.gov (United States)

    Mitchell, Philip C. H.

    1997-10-01

    Stability constants of metal complexes of edta with main group and transition metals are correlated with properties of the elements and cations (ion charge, atomic and ionic radii, ionization energies and electronegativities) and interpreted with an ionic bonding model including a covalent contribution. Enthalpy and entropy contributions are discussed. It is shown how chemists recognize patterns in data with the help of a general theory and so develop a model.

  15. Characteristics of metal and ceramic total hip bearing surfaces and their effect on long-term ultra high molecular weight polyethylene wear.

    Science.gov (United States)

    Davidson, J A

    1993-09-01

    The micromechanics of ultra high molecular weight polyethylene (UHMWPE) wear in total hip replacement are very complex. Polyethylene wear from the metal head and debris formation are two common types of wear. There are additional wear-related processes occurring at the metal-bearing surfaces that are not well-known, however. This study outlines these processes, including (1) surface wettability changes, (2) oxidative wear of metal surfaces, (3) microabrasion of metal surfaces from oxide film damage, and (4) surface abrasion from three-body polymethylmethacrylate and bone debris. These processes can contribute to metal ion release and a gradual increase in the roughness of the metal surfaces. This can lead to increased long-term UHMWPE wear. Of the metal alloys currently used in total hip replacements, Co-Cr-Mo alloy is significantly more resistant to roughening processes. Hard, stable, oxide: ceramic surfaces articulating against UHMWPE are essentially immune to these surface-roughening processes, however. In addition, they provide a more wettable surface, further minimizing polyethylene wear relative to metal surfaces. By analyzing metal release rates from metal-polyethylene wear tests, it is shown here that Co-Cr-Mo is gradually removed at a rate of about 0.1 micron per year (10(6) cycles), whereas 316L stainless steel is removed on the order of 0.2 microns per year and Ti-6Al-4V on the order of 1 micron per year. The wear rate of Co-Cr-Mo articulating against itself is reported to be still greater, at about 2-4 microns per year after an initial wear-in period. Because metal is gradually removed with articulation time, surface-hardening methods such as nitrogen ion implantation can be expected to provide only temporary resistance to these metal removal and surface-roughening processes. Hard, stable ceramic surfaces such as Al2O3 and ZrO2, however, can be expected to maintain their initial surface finish and thus minimize UHMWPE wear in the long term.

  16. Effect of complex amino acid imbalance on growth of tumor in tumor-bearing rats

    Institute of Scientific and Technical Information of China (English)

    Yin-Cheng He; Yuan-Hong Wang; Jun Cao; Ji-Wei Chen; Ding-Yu Pan; Ya-Kui Zhou

    2003-01-01

    AIM: To investigate the effect of complex amino acid imbalance on the growth of tumor in tumor-bearing (TB) rats.METHODS: Sprague-Dawlley (SD) rats underwent jejunostomy for nutritional support. A suspension of Walker256 carcinosarcoma cells was subcutaneously inoculated.TB rats were randomly divided into groups A, B, C and D according to the formula of amino acids in enteral nutritional solutions, respectively. TB rats received jejunal feedings supplemented with balanced amino acids (group A),methionine-depleted amino acids (group B), valine-depleted amino acids (group C) and methionine- and valine-depleted complex amino acid imbalance (group D) for 10 days. Tumor volume, inhibitory rates of tumor, cell cycle and life span of TB rats were investigated.RESULTS: The G0/G1 ratio of tumor cells in group D (80.5±9.0) % was higher than that in groups A, B and C which was 67.0±5.1 %, 78.9±8.5 %, 69.2±6.2 %, respectively (P<0.05). The ratio of S/G2M and PI in group D were lower than those in groups A, B and C. The inhibitory rate of tumor in groups B, C and D was 37.2 %, 33.3 % and 43.9 %,respectively (P<0.05). The life span of TB rats in group D was significantly longer than that in groups B, C, and A.CONCLUSION: Methionine/valine-depleted amino acid imbalance can inhibit tumor growth. Complex amino acids of methionine and valine depleted imbalance have stronger inhibitory effects on tumor growth.

  17. Synthesis, Properties, and Light-Emitting Electrochemical Cell (LEEC) Device Fabrication of Cationic Ir(III) Complexes Bearing Electron-Withdrawing Groups on the Cyclometallating Ligands.

    Science.gov (United States)

    Pal, Amlan K; Cordes, David B; Slawin, Alexandra M Z; Momblona, Cristina; Ortı, Enrique; Samuel, Ifor D W; Bolink, Henk J; Zysman-Colman, Eli

    2016-10-17

    The structure-property relationship study of a series of cationic Ir(III) complexes in the form of [Ir(C^N)2(dtBubpy)]PF6 [where dtBubpy = 4,4'-di-tert-butyl-2,2'-bipyridine and C^N = cyclometallating ligand bearing an electron-withdrawing group (EWG) at C4 of the phenyl substituent, i.e., -CF3 (1), -OCF3 (2), -SCF3 (3), -SO2CF3 (4)] has been investigated. The physical and optoelectronic properties of the four complexes were comprehensively characterized, including by X-ray diffraction analysis. All the complexes exhibit quasireversible dtBubpy-based reductions from -1.29 to -1.34 V (vs SCE). The oxidation processes are likewise quasireversible (metal + C^N ligand) and are between 1.54 and 1.72 V (vs SCE). The relative oxidation potentials follow a general trend associated with the Hammett parameter (σ) of the EWGs. Surprisingly, complex 4 bearing the strongest EWG does not adhere to the expected Hammett behavior and was found to exhibit red-shifted absorption and emission maxima. Nevertheless, the concept of introducing EWGs was found to be generally useful in blue-shifting the emission maxima of the complexes (λem = 484-545 nm) compared to that of the prototype complex [Ir(ppy)2(dtBubpy)]PF6 (where ppy = 2-phenylpyridinato) (λem = 591 nm). The complexes were found to be bright emitters in solution at room temperature (ΦPL = 45-66%) with microsecond excited-state lifetimes (τe = 1.14-4.28 μs). The photophysical properties along with density functional theory (DFT) calculations suggest that the emission of these complexes originates from mixed contributions from ligand-centered (LC) transitions and mixed metal-to-ligand and ligand-to-ligand charge transfer (LLCT/MLCT) transitions, depending on the EWG. In complexes 1, 3, and 4 the (3)LC character is prominent over the mixed (3)CT character, while in complex 2, the mixed (3)CT character is much more pronounced, as demonstrated by DFT calculations and the observed positive solvatochromism effect. Due to the

  18. Proteins in load-bearing junctions: the histidine-rich metal-binding protein of mussel byssus.

    Science.gov (United States)

    Zhao, Hua; Waite, J Herbert

    2006-11-28

    Building complex load-bearing scaffolds depends on effective ways of joining functionally different biomacromolecules. The junction between collagen fibers and foamlike adhesive plaques in mussel byssus is robust despite the strikingly dissimilar connected structures. mcfp-4, the matrix protein from this junction, and its presecreted form from the foot tissue of Mytilus californianus were isolated and characterized. mcfp-4 has a mass of approximately 93 kDa as determined by MALDI-TOF mass spectrometry. Its composition is dominated by histidine (22 mol %), but levels of lysine, arginine, and aspartate are also significant. A small amount of 3,4-dihydroxyphenyl-l-alanine (2 mol %) can be detected by amino acid analysis and redox cycling assays. The cDNA-deduced sequence of mcfp-4 reveals multiple variants with highly repetitive internal structures, including approximately 36 tandemly repeated His-rich decapeptides (e.g., HVHTHRVLHK) in the N-terminal half and 16 somewhat more degenerate aspartate-rich undecapeptides (e.g., DDHVNDIAQTA) in the C-terminal half. Incubation of a synthetic peptide based on the His-rich decapeptide with Fe3+, Co2+, Ni2+, Zn2+, and Cu2+ indicates that only Cu is strongly bound. MALDI-TOF mass spectrometry of the peptide modified with diethyl pyrocarbonate before and after Cu binding suggests that histidine residues dominate Cu binding. In contrast, the aspartate-rich undecapeptides preferentially bind Ca2+. mcfp-4 is strategically positioned to function as a macromolecular bifunctional linker by using metal ions to couple its own His-rich domains to the His-rich termini of the preCOLs. Ca2+ may mediate coupling of the C-terminus to other calcium-binding plaque proteins.

  19. Homogeneous Catalysis with Metal Complexes Fundamentals and Applications

    CERN Document Server

    Duca, Gheorghe

    2012-01-01

    The book about homogeneous catalysis with metal complexes deals with the description of the reductive-oxidative, metal complexes  in a liquid phase (in polar solvents, mainly in water, and less in nonpolar solvents). The exceptional importance of the redox processes in chemical systems, in the reactions occuring in living organisms, the environmental processes, atmosphere, water, soil, and in industrial technologies (especially in food-processing industries) is discussed. The detailed practical aspects of the established regularities are explained for solving the specific practical tasks in various fields of industrial chemistry, biochemistry, medicine, analytical chemistry and ecological chemistry. The main scope of the book is the survey and systematization of the latest advances in homogeneous catalysis with metal complexes. It gives an overview of the research results and practical experience accumulated by the author during the last decade.

  20. Complexation-induced supramolecular assembly drives metal-ion extraction.

    Science.gov (United States)

    Ellis, Ross J; Meridiano, Yannick; Muller, Julie; Berthon, Laurence; Guilbaud, Philippe; Zorz, Nicole; Antonio, Mark R; Demars, Thomas; Zemb, Thomas

    2014-09-26

    Combining experiment with theory reveals the role of self-assembly and complexation in metal-ion transfer through the water-oil interface. The coordinating metal salt Eu(NO3)3 was extracted from water into oil by a lipophilic neutral amphiphile. Molecular dynamics simulations were coupled to experimental spectroscopic and X-ray scattering techniques to investigate how local coordination interactions between the metal ion and ligands in the organic phase combine with long-range interactions to produce spontaneous changes in the solvent microstructure. Extraction of the Eu(3+)-3(NO3(-)) ion pairs involves incorporation of the "hard" metal complex into the core of "soft" aggregates. This seeds the formation of reverse micelles that draw the water and "free" amphiphile into nanoscale hydrophilic domains. The reverse micelles interact through attractive van der Waals interactions and coalesce into rod-shaped polynuclear Eu(III) -containing aggregates with metal centers bridged by nitrate. These preorganized hydrophilic domains, containing high densities of O-donor ligands and anions, provide improved Eu(III) solvation environments that help drive interfacial transfer, as is reflected by the increasing Eu(III) partitioning ratios (oil/aqueous) despite the organic phase approaching saturation. For the first time, this multiscale approach links metal-ion coordination with nanoscale structure to reveal the free-energy balance that drives the phase transfer of neutral metal salts.

  1. Medicinal organometallic chemistry: designing metal arene complexes as anticancer agents.

    Science.gov (United States)

    Peacock, Anna F A; Sadler, Peter J

    2008-11-13

    The field of medicinal inorganic chemistry is rapidly advancing. In particular organometallic complexes have much potential as therapeutic and diagnostic agents. The carbon-bound and other ligands allow the thermodynamic and kinetic reactivity of the metal ion to be controlled and also provide a scaffold for functionalization. The establishment of structure-activity relationships and elucidation of the speciation of complexes under conditions relevant to drug testing and formulation are crucial for the further development of promising medicinal applications of organometallic complexes. Specific examples involving the design of ruthenium and osmium arene complexes as anticancer agents are discussed.

  2. Tailoring optical complex fields with nano-metallic surfaces

    Directory of Open Access Journals (Sweden)

    Rui Guanghao

    2015-04-01

    Full Text Available Recently there is an increasing interest in complex optical fields with spatially inhomogeneous state of polarizations and optical singularities. Novel effects and phenomena have been predicted and observed for light beams with these unconventional states. Nanostructured metallic thin film offers unique opportunities to generate, manipulate and detect these novel fields. Strong interactions between nano-metallic surfaces and complex optical fields enable the development of highly compact and versatile functional devices and systems. In this review, we first briefly summarize the recent developments in complex optical fields. Various nano-metallic surface designs that can produce and manipulate complex optical fields with tailored characteristics in the optical far field will be presented. Nano-metallic surfaces are also proven to be very effective for receiving and detection of complex optical fields in the near field. Advances made in this nascent field may enable the design of novel photonic devices and systems for a variety of applications such as quantum optical information processing and integrated photonic circuits.

  3. Luminescent molecular rods - transition-metal alkynyl complexes.

    Science.gov (United States)

    Yam, Vivian Wing-Wah; Wong, Keith Man-Chung

    2005-01-01

    A number of transition-metal complexes have been reported to exhibit rich luminescence, usually originating from phosphorescence. Such luminescence properties of the triplet excited state with a large Stoke's shift, long lifetime, high luminescence quantum yield as well as lower excitation energy, are envisaged to serve as an ideal candidate in the area of potential applications for chemosensors, dye-sensitized solar cells, flat panel displays, optics, new materials and biological sciences. Organic alkynes (poly-ynes), with extended or conjugatedπ-systems and rigid structure with linear geometry, have become a significant research area due to their novel electronic and physical properties and their potential applications in nanotechnology. Owing to the presence of unsaturated sp-hybridized carbon atoms, the alkynyl unit can serve as a versatile building block in the construction of alkynyl transition-metal complexes, not only throughσ-bonding but also viaπ-bonding interactions. By incorporation of linear alkynyl groups into luminescent transition-metal complexes, the alkynyl moiety with goodσ-donor,π-donor andπ-acceptor abilities is envisaged to tune or perturb the emission behaviors, including emission energy (color), intensity and lifetime by its role as an auxiliary ligand as well as to govern the emission origin from its direct involvement. This review summarizes recent efforts on the synthesis of luminescent rod-like alkynyl complexes with different classes of transition metals and details the effects of the introduction of alkynyl groups on the luminescence properties of the complexes.

  4. Carbothermic Reduction Reactions at the Metal-Slag Interface in Ti-Bearing Slag from a Blast Furnace

    Science.gov (United States)

    Wang, Yao-Zu; Zhang, Jian-Liang; Liu, Zheng-Jian; Du, Cheng-Bo

    2017-08-01

    Carbothermic reduction reactions at the metal-slag interface and the mechanisms of iron loss during the smelting of vanadium-bearing titanomagnetite in a blast furnace are still not clear as a result of the limited ability to observe the high-temperature zone of a blast furnace. The chemical composition of a Ti-bearing slag was determined by x-ray fluorescence and x-ray diffraction. The interfaces were characterized by scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy. The interfacial chemical reactions were deduced based on the characterization results and on the thermodynamic calculations performed using Factsage 6.4. The results indicated that the forms of iron in the slag were iron droplets wetted by Ti(C x , N1-x ), mechanically separated by iron and iron oxide. The different forms possessed unique characteristics and were formed by different mechanisms. Iron droplets wetted by Ti(C x , N1-x ) were generated through a series of interfacial reactions between TiO2 in the slag and [C] and [N] in the metal. Iron droplets without attached Ti(C x , N1-x ) were mainly located on the edges of pores and were attributed to the reduction of Fe x O in the slag. Insufficient reduction of iron-bearing minerals made it difficult for iron droplets to aggregate and separate from the slag, which created an Fe x O-enriched zone.

  5. Bioactivities of Novel Metal Complexes Involving B Vitamins and Glycine

    Directory of Open Access Journals (Sweden)

    Fazary Ahmed E.

    2016-01-01

    Full Text Available In this work twelve novel mixed ligand complexes were synthesized. The complexes were formed between a metal ion (Cu(II, Cd(II, Mn(II, Fe(III, Ni(II, Pb(II and vitamins (B 3 and B 9 as primary ligands, and glycine as secondary ligand. Melting points, conductivities, and magnetic susceptibilities of the synthesized complexes were determined and the complexes were subjected to elemental analyses. The presence of coordination water molecules in the complex was also supported by TG/DTG thermal analysis. Full elucidation of the molecular structures for the synthesized mixed ligand complexes were confirmed using detailed spectroscopic IR, 1H-, 13C-NMR, and XRD techniques. In addition, cytotoxic and antioxidant activities of the twelve synthesized solid complexes were tested to evaluate their bioactivities.

  6. Thallium and manganese complexes involved in the luminescence emission of potassium-bearing aluminosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Gonzalez, Miguel A., E-mail: miguel.gomez@mncn.csic.es [Museo Nacional de Ciencias Naturales, CSIC, Jose Gutierrez Abascal 2, Madrid E-28006 (Spain); Garcia-Guinea, Javier, E-mail: guinea@mncn.csic.es [Museo Nacional de Ciencias Naturales, CSIC, Jose Gutierrez Abascal 2, Madrid E-28006 (Spain); Garrido, Fernando, E-mail: fernando.garrido@mncn.csic.es [Museo Nacional de Ciencias Naturales, CSIC, Jose Gutierrez Abascal 2, Madrid E-28006 (Spain); Townsend, Peter D., E-mail: pdtownsend@gmail.com [School of Science and Technology, University of Sussex, Brighton BN1 9QH (United Kingdom); Marco, Jose-Francisco, E-mail: jfmarco@iqfr.csic.es [Instituto de Química-Física Rocasolano, CSIC, Calle Serrano 119, Madrid E-28006 (Spain)

    2015-03-15

    The luminescence emission at 285 nm in natural K-feldspar has been studied by Russian groups and associated with thallium ions in structural positions of K{sup +} sites as artificially thallium-doped feldspars display the same emission band. Here attention is focussed on spectra of CL emission bands centered near 285 and 560 nm from paragenetic adularia, moscovite and quartz micro-inclusions. With accesorial thallium they show clear resemblances to each other. Associated sedimentary and hydrothermal aluminosilicate samples collected from Guadalix (Madrid, Spain) were analyzed with a wide range of experimental techniques including Environmental Scanning Electron Microscopy (ESEM) with an attached X-Ray Energy-Dispersive Spectrometer (EDS) and a cathodoluminescence probe (CL) and Electron Probe Microanalysis (EPMA), X-Ray Fluorescence Spectrometry (XRF), Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), Differential and Thermogravimetric Analyses (DTA-TG), radioluminescence (RL), Mössbauer spectroscopy and X-Ray Photoelectron Spectrometry (XPS). The luminescence emission bands at 285 and 560 nm seem to be associated with hydrous thallium–manganese complexes bonded to potassium-bearing aluminosilicates since various minerals such as K-feldspar, moscovite and quartz micro-inclusions display similar CL spectra, accesorial thallium and hydroxyl groups. The presence of iron introduces a brown color which is attributed to submicroscopic iron oxides detectable in the optical and chemical microanalysis, but this does not contribute to the luminescence emission. The XPS Mn 2p spectrum of the adularia sample at room temperature is composed of a spin–orbit doublet plus clear shake-up satellite structure ∼4 eV above the main photoemision lines and is consistent with Mn{sup 2+} in good agreement with the observed luminescence emission at 560 nm for aluminosilicates produced by a {sup 4}T1({sup 4}G)→{sup 6}A1({sup 6}S) transition in tetrahedrally

  7. Metal ion coordination, conditional stability constants, and solution behavior of chelating surfactant metal complexes.

    Science.gov (United States)

    Svanedal, Ida; Boija, Susanne; Almesåker, Ann; Persson, Gerd; Andersson, Fredrik; Hedenström, Erik; Bylund, Dan; Norgren, Magnus; Edlund, Håkan

    2014-04-29

    Coordination complexes of some divalent metal ions with the DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of chelation and solution behavior. The headgroup of 4-C12-DTPA contains eight donor atoms that can participate in the coordination of a metal ion. Conditional stability constants for five transition metal complexes with 4-C12-DTPA were determined by competition measurements between 4-C12-DTPA and DTPA, using electrospray ionization mass spectrometry (ESI-MS). Small differences in the relative strength between the coordination complexes of DTPA and 4-C12-DTPA indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. The coordination of Cu(2+) ions was investigated in particular, using UV-visible spectroscopy. By constructing Job's plots, it was found that 4-C12-DTPA could coordinate up to two Cu(2+) ions. Surface tension measurements and NMR diffusometry showed that the coordination of metal ions affected the solution behavior of 4-C12-DTPA, but there were no specific trends between the studied divalent metal complexes. Generally, the effects of the metal ion coordination could be linked to the neutralization of the headgroup charge of 4-C12-DTPA, and the resulting reduced electrostatic repulsions between adjacent surfactants in micelles and monolayers. The pH vs concentration plots, on the other hand, showed a distinct difference between 4-C12-DTPA complexes of the alkaline earth metals and the transition metals. This was explained by the difference in coordination between the two groups of metal ions, as predicted by the hard and soft acid and base (HSAB) theory.

  8. A finite element analysis of a large thrust elastic metal-plastics bearing bush for a hydraulic turbine

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Presents the study on the pressure and friction fields of the lubricant film on the surface of a large thrust elastic metal-plastic bearing bush in a hydraulic turbine using the method of finite element analysis and the stress and displacement fields in the vertical direction of the bush surface obtained to provide a theoretical basis for the design of contour lines and investigation into the causes for destruction of bushes, and concludes with test results that 1 ) the stress on the surface of the bush is not uniform; 2) a tension stress tends to occur near the oil ingress and egress edges but it is minor; 3) the biggest displacement in the vertical direction appears where x = 84 and Y = 1 153 and has a value of 0.022 mm; 4) the deformation of the bearing bush is harmful to the maintenance of lubricant film.

  9. Influences of Technological Parameters on Smelting-separation Process for Metallized Pellets of Vanadium-bearing Titanomagnetite Concentrates

    Institute of Scientific and Technical Information of China (English)

    En-hui WU; Rong ZHU; Shao-li YANG; Lan MA; Jun LI; Jing HOU

    2016-01-01

    The smelting-separation process for metallized pellets of vanadium-bearing titanomagnetite concentrates was studied.The influences of smelting temperature,smelting time,and the basicity of the metallized pellet on vana-dium and iron recovery were investigated.The characteristics of titanium slag were analyzed using X-ray diffraction, energy dispersive spectroscopy,and mineralographic microscopic analysis.The results demonstrate that appropriate increases in smelting temperature and smelting time can improve the vanadium and iron recovery from metallized pel-lets and are beneficial for the slag-iron separation.Although increasing the basicity of the metallized pellet can consid-erably improve the vanadium and iron recovery,the TiO2 grade of titanium slag was decreased.Under the optimal conditions,90·17% of vanadium and 92·98% of iron in the metallized pellet were recovered,and the TiO2 grade of titanium slag was 55·01%.It was found that anosovite,augite,spinel,glassiness,and metallic iron were the main mineral phases of the titanium slag.

  10. The Potential of a Clinch-Lock Polymer Metal Hybrid Technology for Use in Load-Bearing Automotive Components

    Science.gov (United States)

    Grujicic, M.; Sellappan, V.; Arakere, G.; Seyr, Norbert; Obieglo, Andreas; Erdmann, Marc; Holzleitner, Jochen

    2009-10-01

    In order to help meet the needs of automotive original equipment manufacturers and their suppliers for a cost-effective, robust, reliable polymer-metal-hybrid (PMH) technology which can be used for the manufacturing of load-bearing body-in-white (BIW) components and which is compatible with the current BIW manufacturing process chain, a new approach, the so-called direct-adhesion PMH technology, was recently proposed (Grujicic et al., J. Mater. Process. Technol., 2008, 195, p 282-298). Within this approach, the necessary level of polymer-to-metal mechanical interconnectivity is attained through direct adhesion and mechanical interlocking. In the present work, a new concept for mechanical interlocking between the metal and plastics is proposed and analyzed computationally. The approach utilizes some of the ideas used in the spot-clinching joining process and is appropriately named clinch-lock PMH technology. To assess the potential of the clinch-lock approach for providing the required level of metal/polymer mechanical interlocking, a set of finite-element based sheet-metal forming, injection molding and structural mechanics analyses was carried out. The results obtained show that stiffness and buckling resistance levels can be attained which are comparable with those observed in the competing injection overmolding PMH process but with an ~3% lower weight (of the polymer subcomponent) and without the need for holes and for overmolding of the free edges of the metal stamping.

  11. Quantitative investigations of cation complexation of photochromic 8-benzothiazole-substituted benzopyran: towards metal-ion sensors.

    Science.gov (United States)

    Zakharova, Marianna I; Coudret, Christophe; Pimienta, Véronique; Micheau, Jean Claude; Delbaere, Stéphanie; Vermeersch, Gaston; Metelitsa, Anatoly V; Voloshin, Nikolai; Minkin, Vladimir I

    2010-02-01

    The photochromic, thermochromic and metallochromic behaviour of a series of three spiro[indoline-8-(benzothiazol-2-yl)-benzopyrans] has been investigated. The thermodynamic and kinetic parameters of their thermal equilibrium between the ring-closed (spiro) and ring-opened (merocyanine) isomeric forms have been determined using UV-Vis absorption and (1)H NMR spectroscopies. By adding Co(ii) and Ni(ii) ions in acetonitrile solution, 1 : 1 and 1 : 2 metal : merocyanine complexes are formed simultaneously. Using appropriate numerical methods, the kinetic analysis of the complexation allowed us to determine accurately key thermodynamic and spectroscopic parameters of the metal complexes. Results showed that the complexation strength is very sensitive to the size of the indoline nitrogen substituent. Complexation can be reversed by shining white light on the coloured complexes which regenerates the inactive spiropyran form, and releases the metallic ion; hence, these systems display fully reversible negative photochromism. The Zn(ii) complexes exhibit intense fluorescence in the 600-800 nm wavelength range. All these behaviours make these spiropyrans bearing benzothiazole heterocycles promising building blocks for the future construction of photodynamic chemosensors for transition metal ions.

  12. Dimeric Complexes of Tryptophan with M2+ Metal Ions

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Polfer, N. C.; Oomens, J.

    2009-01-01

    IRMPD spectroscopy using the FELIX free electron laser and a Fourier transform ICR mass spectrometer was used to characterize the structures of electrosprayed dimer complexes M(2+)Trp(2) of tryptophan with a series of eight doubly charged metal ions, including alkaline earths Ca, Sr, and Ba, and tra

  13. [Applications of metal ions and their complexes in medicine I].

    Science.gov (United States)

    Nagy, László; Csintalan, Gabriella; Kálmán, Eszter; Sipos, Pál; Szvetnik, Attila

    2003-01-01

    The "inorganic medical chemistry" is a rapidly developing field with enormous potential for applications, which offers new possibilities to the pharmaceutical industry. For example, the titanocene dichloride is already in clinical use, and antimetastatic activity of a range of Ru(III) complexes is also well established. There are ways to minimize the toxicity of Gd(III) complexes and therefore they can be safely injected as MRI contrast agents. The so called "ligand design" allows paramagnetic ions to be targeted to specific organs. Such designed ligands also enable the targeting of radiodiagnostic (99mTc) and radiotherapeutic (186Re) isotopes. There is a significant progress in understanding the coordination chemistry and biochemistry of metal ion(s) containing complexes such as Au antiarthritic and Bi antiulcer drugs. Further, currently developing areas include Mn (SOD mimics), V (insulin mimics), Ru (NO scavengers), Ln-based photosensitizers, metal-targeted organic agents and the Fe overload. The expanding knowledge of the role of metals in biochemistry is expected to provide scope for the design of new drugs in many other areas too, for example neuropharmaceutical and antiaffective agents. Progress in coordination chemistry is strongly dependent on understanding not only the thermodynamics of reactions, but also the kinetics of metal complexes under biologically relevant conditions.

  14. Metal Complexes as Color Indicators for Solvent Parameters.

    Science.gov (United States)

    Soukup, Rudolf W.; Schmid, Roland

    1985-01-01

    Although indicators are omnipresent tools in aqueous chemistry, they have not been used extensively to assign solvent properties in nonaqueous systems. Therefore, recent research into a system of metal complexes that can be used to assign donor and acceptor numbers to nonaqueous solvents is summarized. Pertinent experiments are also described. (JN)

  15. Synthesis and characterization of some metal complexes of a Schiff ...

    African Journals Online (AJOL)

    analysis, molar conductance, magnetic susceptibility, infrared and electronic ... stops at the first step, the metal ion forming a highly stable colored complex with the ..... *Intensities in parenthesis: b-broad, vs-very strong, s-strong, m-medium, ...

  16. Single-Molecule Conductance Studies of Organometallic Complexes Bearing 3-Thienyl Contacting Groups.

    Science.gov (United States)

    Bock, Sören; Al-Owaedi, Oday A; Eaves, Samantha G; Milan, David C; Lemmer, Mario; Skelton, Brian W; Osorio, Henrry M; Nichols, Richard J; Higgins, Simon J; Cea, Pilar; Long, Nicholas J; Albrecht, Tim; Martín, Santiago; Lambert, Colin J; Low, Paul J

    2017-02-10

    The compounds and complexes 1,4-C6 H4 (C≡C-cyclo-3-C4 H3 S)2 (2), trans-[Pt(C≡C-cyclo-3-C4 H3 S)2 (PEt3 )2 ] (3), trans-[Ru(C≡C-cyclo-3-C4 H3 S)2 (dppe)2 ] (4; dppe=1,2-bis(diphenylphosphino)ethane) and trans-[Ru(C≡C-cyclo-3-C4 H3 S)2 {P(OEt)3 }4 ] (5) featuring the 3-thienyl moiety as a surface contacting group for gold electrodes have been prepared, crystallographically characterised in the case of 3-5 and studied in metal|molecule|metal junctions by using both scanning tunnelling microscope break-junction (STM-BJ) and STM-I(s) methods (measuring the tunnelling current (I) as a function of distance (s)). The compounds exhibit similar conductance profiles, with a low conductance feature being more readily identified by STM-I(s) methods, and a higher feature by the STM-BJ method. The lower conductance feature was further characterised by analysis using an unsupervised, automated multi-parameter vector classification (MPVC) of the conductance traces. The combination of similarly structured HOMOs and non-resonant tunnelling mechanism accounts for the remarkably similar conductance values across the chemically distinct members of the family 2-5.

  17. Vibrational energy transfer dynamics in ruthenium polypyridine transition metal complexes.

    Science.gov (United States)

    Fedoseeva, Marina; Delor, Milan; Parker, Simon C; Sazanovich, Igor V; Towrie, Michael; Parker, Anthony W; Weinstein, Julia A

    2015-01-21

    Understanding the dynamics of the initial stages of vibrational energy transfer in transition metal complexes is a challenging fundamental question which is also of crucial importance for many applications, such as improving the performance of solar devices or photocatalysis. The present study investigates vibrational energy transport in the ground and the electronic excited state of Ru(4,4'-(COOEt)2-2,2-bpy)2(NCS)2, a close relative of the efficient "N3" dye used in dye-sensitized solar cells. Using the emerging technique of ultrafast two-dimensional infrared spectroscopy, we show that, similarly to other transition-metal complexes, the central Ru heavy atom acts as a "bottleneck" making the energy transfer from small ligands with high energy vibrational stretching frequencies less favorable and thereby affecting the efficiency of vibrational energy flow in the complex. Comparison of the vibrational relaxation times in the electronic ground and excited state of Ru(4,4'-(COOEt)2-2,2-bpy)2(NCS)2 shows that it is dramatically faster in the latter. We propose to explain this observation by the intramolecular electrostatic interactions between the thiocyanate group and partially oxidised Ru metal center, which increase the degree of vibrational coupling between CN and Ru-N modes in the excited state thus reducing structural and thermodynamic barriers that slow down vibrational relaxation and energy transport in the electronic ground state. As a very similar behavior was earlier observed in another transition-metal complex, Re(4,4'-(COOEt)2-2,2'-bpy)(CO)3Cl, we suggest that this effect in vibrational energy dynamics might be common for transition-metal complexes with heavy central atoms.

  18. The effect of Ca-Fe-As coatings on microbial leaching of metals in arsenic bearing mine waste

    Energy Technology Data Exchange (ETDEWEB)

    Weisener, C.G.; Guthrie, J.W.; Smeaton, C.M.; Paktunc, D.; Fryer, B.J. (Windsor); (NRC)

    2011-11-07

    Globally arsenic (As) is a ubiquitous trace element derived from the natural weathering of As-bearing rock. With the onset of reducing conditions, the prevalence of aqueous As(III) may be intensified through biotic and abiotic processes. Here we evaluate the stability of arsenic bearing Ca-Fe hydroxide phases collected from exposed tailings at Ketza River mine, Yukon, Canada, during the reductive dissolution of both acid treated and untreated samples by Shewanella putrefaciens 200R and Shewanella sp. ANA-3. Samples were acid treated in order to remove Ca-Fe oxide coatings and evaluate the influence of these coatings on the rates of microbial Fe(III) and As(V) reduction. Environmental scanning electron microscope (ESEM) micrographs of the solid phase show significant differences in the chemistry and physical morphology of the material by the bacteria over time and are especially evident in the acid treated samples. Moreover, while solution chemistry showed similar As(III) respiration rates of the inoculated acid treated samples for both ANA3 and 200R at {approx}1.1 x 10{sup -6} {micro}M {center_dot} s{sup -1} {center_dot} m{sup -2}, the Fe(II) respiration rates differed at 1.4 x 10{sup -7} and 9.5 x 10{sup -8} {micro}M {center_dot} s{sup -1} {center_dot} m{sup -2} respectively, thus suggesting strain specific metal reduction metabolic pathways Additionally, the enhanced metal reduction observed in the acid treated inoculated samples suggests that the presence of the Ca-Fe hydroxide phase in the untreated samples acted as a barrier, inhibiting the bacteria from accessing the metals. This has implications for increased mobilization of metals by metal reducing bacteria within areas of increased acidity, such as acid mine drainage sites and industrial tailings ponds that can come into contact with surface and ground water sources.

  19. Surface Complexation Modelling in Metal-Mineral-Bacteria Systems

    Science.gov (United States)

    Johnson, K. J.; Fein, J. B.

    2002-12-01

    The reactive surfaces of bacteria and minerals can determine the fate, transport, and bioavailability of aqueous heavy metal cations. Geochemical models are instrumental in accurately accounting for the partitioning of the metals between mineral surfaces and bacteria cell walls. Previous research has shown that surface complexation modelling (SCM) is accurate in two-component systems (metal:mineral and metal:bacteria); however, the ability of SCMs to account for metal distribution in mixed metal-mineral-bacteria systems has not been tested. In this study, we measure aqueous Cd distributions in water-bacteria-mineral systems, and compare these observations with predicted distributions based on a surface complexation modelling approach. We measured Cd adsorption in 2- and 3-component batch adsorption experiments. In the 2-component experiments, we measured the extent of adsorption of 10 ppm aqueous Cd onto either a bacterial or hydrous ferric oxide sorbent. The metal:bacteria experiments contained 1 g/L (wet wt.) of B. subtilis, and were conducted as a function of pH; the metal:mineral experiments were conducted as a function of both pH and HFO content. Two types of 3-component Cd adsorption experiments were also conducted in which both mineral powder and bacteria were present as sorbents: 1) one in which the HFO was physically but not chemically isolated from the system using sealed dialysis tubing, and 2) others where the HFO, Cd and B. subtilis were all in physical contact. The dialysis tubing approach enabled the direct determination of the concentration of Cd on each sorbing surface, after separation and acidification of each sorbent. The experiments indicate that both bacteria and mineral surfaces can dominate adsorption in the system, depending on pH and bacteria:mineral ratio. The stability constants, determined using the data from the 2-component systems, along with those for other surface and aqueous species in the systems, were used with FITEQL to

  20. Polyporphyrin Complexes of Some Transition Metals. Synthesis and Catalytic Properties

    Directory of Open Access Journals (Sweden)

    A.V. Shakhvorostov

    2016-10-01

    Full Text Available The paper presents the results of synthesis of polyporphyrin structures and metal complex catalyzers at their basis. Porphyrin to be derived from the addition reaction of pyrrole and formaldehyde. Metal complex catalyzers to be derived at the reaction of complex formation of ions of Mn2+, Co2+, Ni2+ and Fe3+ with porphyrin. The structure, physical and chemical properties of derived materials to be examined with IR spectroscopy, differential thermal analysis, thermogravimetric analysis, scanning electron microscopy investigation. Catalytic activity of synthesized catalytic systems to be established at the reaction of decompounding of hydrogen peroxide and alkylaromatics oxidation by hydrogen peroxide. The processes have been conducted under soft conditions, and also at different organic solvents.

  1. Highly selective and sensitive DNA assay based on electrocatalytic oxidation of ferrocene bearing zinc(II)-cyclen complexes with diethylamine.

    Science.gov (United States)

    Shiddiky, Muhammad J A; Torriero, Angel A J; Zeng, Zhanghua; Spiccia, Leone; Bond, Alan M

    2010-07-28

    A highly selective and sensitive electrochemical biosensor has been developed that detects DNA hybridization by employing the electrocatalytic activity of ferrocene (Fc) bearing cyclen complexes (cyclen = 1,4,7,10-tetraazacyclododecane, Fc[Zn(cyclen)H(2)O](2)(ClO(4))(4) (R1), Fc(cyclen)(2) (R2), Fc[Zn(cyclen)H(2)O](ClO(4))(2) (R3), and Fc(cyclen) (R4)). A sandwich-type approach, which involves hybridization of a target probe hybridized with the preimmobilized thiolated capture probe attached to a gold electrode, is employed to fabricate a DNA duplex layer. Electrochemical signals are generated by voltammetric interrogation of a Fc bearing Zn-cyclen complexes that selectively and quantitatively binds to the duplex layers through strong chelation between the cyclen complexes and particular nucleobases within the DNA sequence. Chelate formation between R1 or R3 and thymine bases leads to the perturbation of base-pair (A-T) stacking in the duplex structure, which greatly diminishes the yield of DNA-mediated charge transport and displays a marked selectivity to the presence of the target DNA sequence. Coupling the redox chemistry of the surface-bound Fc bearing Zn-cyclen complex and dimethylamine provides an electrocatalytic pathway that increases sensitivity of the assay and allows the 100 fM target DNA sequence to be detected. Excellent selectivity against even single-base sequence mismatches is achieved, and the DNA sensor is stable and reusable.

  2. Catalysis by alkali and alkaline-earth metal ions in nucleophilic attack of methoxide ion on crown ethers bearing an intra-annular acetoxy group

    NARCIS (Netherlands)

    Cacciapaglia, Roberta; Lucente, Silvia; Mandolini, Luigi; Doorn, van Arie R.; Reinhoudt, David N.; Verboom, Willem

    1989-01-01

    Rates of reaction of methoxide ion with crown ethers bearing an intra-annular acetoxy group are markedly enhanced by alkali and alkaline-earth metal bromides as a result of much stronger interactions of the metal ions with transition states than with reactants. Rates of reactions of methoxide ion w

  3. Chemical and morphological characteristics of solid metal-bearing phases deposited in snow and stream sediment as indicators of their origin.

    Science.gov (United States)

    Miler, Miloš; Gosar, Mateja

    2015-02-01

    Detailed scanning electron microscopy/energy dispersive spectroscopy of metal-bearing particles in snow deposits and stream sediment from a steelworks area was performed. Identified metal-bearing phases were apportioned according to their chemical and morphological characteristics to anthropogenic phases and secondary weathering products. Anthropogenic metal-bearing phases are the most abundant in both media and are represented by various irregular ferrous oxides, ferrous alloys, spherical ferrous oxides, and ferrous silicates with variable contents of Cr, Mn, Ni, V, W, and Mo. Secondary weathering products are Al silicates, Fe oxy-hydroxides, and Fe oxy-hydroxy sulfates with minor contents of transition metals, resulting from weathering of anthropogenic phases and Pb-Zn ore minerals from a closed Pb-Zn mine located upstream from the study area. Comparison of anthropogenic metal-bearing phases in both media showed agreement in their compositions and morphologies and indicated their sources are high-temperature processes in steel production. It also showed that spherical metal-bearing phases were transported by the same transport medium, which is the atmosphere, while other phases were transported into stream sediment mostly by other pathways, such as precipitation runoff over contaminated surfaces.

  4. Electron transfer and catalysis with high-valent metal-oxo complexes.

    Science.gov (United States)

    Fukuzumi, Shunichi

    2015-04-21

    High-valent metal-oxo complexes are produced by reductive activation of dioxygen via reduction of metal complexes with reductants and dioxygen. Photoinduced electron transfer from substrates to metal complexes with dioxygen also leads to the generation of high-valent metal-oxo complexes that can oxygenate substrates. In such a case metal complexes act as a photocatalyst to oxygenate substrates with dioxygen. High-valent metal-oxo complexes are also produced by proton-coupled electron-transfer oxidation of metal complexes by one-electron oxidants with water, oxygenating substrates to regenerate metal complexes. In such a case metal complexes act as a catalyst for electron-transfer oxygenation of substrates by one-electron oxidants with water that acts as an oxygen source. The one-electron oxidants which can oxidize metal complexes can be replaced by much weaker oxidants by a combination of redox photocatalysts and metal complexes. Thus, photocatalytic oxygenation of substrates proceeds via photoinduced electron transfer from a photocatalyst to reductants followed by proton-coupled electron transfer oxidation of metal complexes with the oxidized photocatalyst to produce high-valent metal-oxo complexes that oxygenate substrates. Thermal and photoinduced electron-transfer catalytic reactions of high-valent metal-oxo complexes for oxygenation of substrates using water or dioxygen as an oxygen source are summarized in this perspective.

  5. Synthesis of some novel divalent transition metal complexes as antimicrobials

    Institute of Scientific and Technical Information of China (English)

    Kaushal K. Oza; Paresh N. Patel; Hasmukh S. Patel

    2011-01-01

    A novel series of transition metal complexes have been synthesized from the reaction of 5-((3-(methylthio)-5-(pyridin-4-yl)-4H-1,2,4-triazol-4-ylamino)methyl)quinolin-8-ol with transition metal salts. The structures of these compounds have been elucidated by elemental and spectral analysis. Furthermore, compounds were screened for in vitro antimicrobial activity against the representative panel of two Gram-positive and two Gram-negative bacteria and two strains of fungus. The various compounds show potent inhibitory action against test organisms.

  6. Ternary metal complexes of guaifenesin drug: Synthesis, spectroscopic characterization and in vitro anticancer activity of the metal complexes.

    Science.gov (United States)

    Mahmoud, W H; Mahmoud, N F; Mohamed, G G; El-Sonbati, A Z; El-Bindary, A A

    2015-01-01

    The coordination behavior of a series of transition metal ions named Cr(III), Fe(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with a mono negative tridentate guaifenesin ligand (GFS) (OOO donation sites) and 1,10-phenanthroline (Phen) is reported. The metal complexes are characterized based on elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance, UV-vis spectral studies, mass spectroscopy, ESR, XRD and thermal analysis (TG and DTG). The ternary metal complexes were found to have the formulae of [M(GFS)(Phen)Cl]Cl·nH2O (M=Cr(III) (n=1) and Fe(III) (n=0)), [M(GFS)(Phen)Cl]·nH2O (M=Mn(II) (n=0), Zn(II) (n=0) and Cu(II) (n=3)) and [M(GFS)(Phen)(H2O)]Cl·nH2O (M=Co(II) (n=0), Ni(II) (n=0) and Cd(II) (n=4)). All the chelates are found to have octahedral geometrical structures. The ligand and its ternary chelates are subjected to thermal analyses (TG and DTG). The GFS ligand, in comparison to its ternary metal complexes also was screened for their antibacterial activity on gram positive bacteria (Bacillus subtilis and Staphylococcus aureus), gram negative bacteria (Escherichia coli and Neisseria gonorrhoeae) and for in vitro antifungal activity against (Candida albicans). The activity data show that the metal complexes have antibacterial and antifungal activity more than the parent GFS ligand. The complexes were also screened for its in vitro anticancer activity against the Breast cell line (MFC7) and the results obtained show that they exhibit a considerable anticancer activity. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. The Nokomis Cu-Ni-PGE Deposit, Duluth Complex: A sulfide-bearing, crystal-laden magmatic slurry

    Science.gov (United States)

    Peterson, D. M.

    2009-12-01

    Duluth Metals Limited’s Nokomis deposit is the most recently discovered Cu-Ni-PGE deposit in the 1.1 Ga. Duluth Complex, Minnesota. The deposit was discovered utilizing a genetic ore deposit model that identified and back-tracked channelized magma flow within the basal zone of the South Kawishiwi intrusion (SKI). The model led to exploratory drilling in 2006, deposit discovery and initial resource estimation in 2007, and significant resource expansion in 2008, all in a period of 18 months. The deposit’s updated 2008 NI 43-101 compliant Resource Estimate, based on 108 holes drilled by Duluth Metals and 52 historic drill holes on and off the property, contains 449 million tonnes of Indicated Resources grading 0.624% copper, 0.199% nickel, and 0.600 grams per tonne of total precious metals (TPM = Platinum+Palladium+Gold), and an additional 284 million tonnes of Inferred Resources grading 0.627% copper, 0.194% nickel, and 0.718 grams per tonne of TPM. The combined Indicated and Inferred Resources contain approximately 10 billion lbs Cu, 3.1 billion lbs Ni, 165 million lbs Co, 4 million ounces Pt, 9 million ounces Pd, and 2 million ounces of Au. Within these NI 43-101 resources are large tonnages of higher grade material, and the company has commenced an internal research program to identify the geologic controls on the formation nickel-rich and PGE-rich mineralization in the SKI, as well as copper-PGE rich mineralization in the footwall Archean rocks. To date, Duluth Metals has drilled more than 500,000 Ft. (~155,000 m) of core in 155 holes into the deposit, and has only drilled about half of the property. The ore deposit model was developed in cooperation with researchers from the Natural Resources Research Institute of the University of Minnesota, Duluth. As well, research and collaboration with faculty and students at Johns Hopkins University on the Ferrar Dolerites of the Antarctic Dry Valleys has played a key role in developing the magmatic model for the

  8. Alumina polymorphs affect the metal immobilization effect when beneficially using copper-bearing industrial sludge for ceramics.

    Science.gov (United States)

    Tang, Yuanyuan; Lu, Xiuqing; Shih, Kaimin

    2014-12-01

    The feasibility of recycling copper-bearing industrial sludge as a part of ceramic raw materials was evaluated through thermal interaction of sludge with aluminum-rich precursors. To observe copper incorporation mechanism, mixtures of copper-bearing sludge with alumina polymorphs (γ-Al2O3 and α-Al2O3) were fired between 750 and 1250°C. Different copper-hosting phases were identified by X-ray diffraction, and CuAl2O4 was found to be the predominant phase throughout the reactions. The experimental results indicate different CuAl2O4 initiating temperatures for two alumina materials, and the optimal temperature for CuAl2O4 formation is around 1100°C. To monitor the stabilization effect, prolonged leaching tests were carried out to leach sintered products for up to 20d. The results clearly demonstrate a substantial decrease in copper leachability for products with higher CuAl2O4 content formed from both alumina precursors despite their different sintering behavior. Meanwhile, the leachability of aluminum was much lower than that of copper, and it decreased by more than fourfold through the formation of CuAl2O4 spinel in γ-Al2O3 system. This study clearly indicates spinel formation as the most crucial metal stabilization mechanism when sintering multiphase copper-bearing industrial sludge with aluminum-rich ceramic raw materials, and suggests a promising and reliable technique for reusing industrial sludge.

  9. Green synthesis of multi metal- citrate complexes and their characterization

    Science.gov (United States)

    Raju, Usha; Warkar, Sudhir G.; Kumar, Anil

    2017-04-01

    Four new multi metal-citrate complexes have been synthesized through green synthetic pathways. Their synthesis by hydrothermal route in the present research is decorated with features such as, a simple one pot synthesis, cost effectiveness, easy to scale up for commercial production, efficient synthesis conditions like mild temperature and shorter duration which further rules out the possibility of forming byproducts which may cause damage to the environment and being environmental benign as it eliminates the use and recovery of harmful organic solvents such as N, N- dimethyl formamide and N, N- diethyl formamide, used by the researchers in the past during the synthesis of similar metal- organic framework complexes. All four complexes are well defined crystalline materials with polynuclear multi metal-citrate framework having cubic crystal structure as indicated by their Powder X-ray Diffraction patterns. These complexes have been characterized by Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Thermogravimetric analysis and Powder XRD techniques.

  10. Photoinduced energy transfer in transition metal complex oligomers

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-04-01

    The work we have done over the past three years has been directed toward the preparation, characterization and photophysical examination of mono- and bimetallic diimine complexes. The work is part of a broader project directed toward the development of stable, efficient, light harvesting arrays of transition metal complex chromophores. One focus has been the synthesis of rigid bis-bidentate and bis-tridentate bridging ligands. We have managed to make the ligand bphb in multigram quantities from inexpensive starting materials. The synthetic approach used has allowed us prepare a variety of other ligands which may have unique applications (vide infra). We have prepared, characterized and examined the photophysical behavior of Ru(II) and Re(I) complexes of the ligands. Energy donor/acceptor complexes of bphb have been prepared which exhibit nearly activationless energy transfer. Complexes of Ru(II) and Re(I) have also been prepared with other polyunsaturated ligands in which two different long lived ( > 50 ns) excited states exist; results of luminescence and transient absorbance measurements suggest the two states are metal-to-ligand charge transfer and ligand localized {pi}{r_arrow}{pi}* triplets. Finally, we have developed methods to prepare polymetallic complexes which are covalently bound to various surfaces. The long term objective of this work is to make light harvesting arrays for the sensitization of large band gap semiconductors. Details of this work are provided in the body of the report.

  11. Photoinduced energy transfer in transition metal complex oligomers

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-06-01

    The work done over the past three years has been directed toward the preparation, characterization and photophysical examination of mono- and bimetallic diimine complexes. The work is part of a broader project directed toward the development of stable, efficient, light harvesting arrays of transition metal complex chromophores. One focus has been the synthesis of rigid bis-bidentate and bis-tridentate bridging ligands. The authors have managed to make the ligand bphb in multigram quantities from inexpensive starting materials. The synthetic approach used has allowed them to prepare a variety of other ligands which may have unique applications (vide infra). They have prepared, characterized and examined the photophysical behavior of Ru(II) and Re(I) complexes of the ligands. Energy donor/acceptor complexes of bphb have been prepared which exhibit nearly activationless energy transfer. Complexes of Ru(II) and Re(I) have also been prepared with other polyunsaturated ligands in which two different long lived (> 50 ns) excited states exist; results of luminescence and transient absorbance measurements suggest the two states are metal-to-ligand charge transfer and ligand localized {pi}{r_arrow}{pi}* triplets. Finally, the authors have developed methods to prepare polymetallic complexes which are covalently bound to various surfaces. The long term objective of this work is to make light harvesting arrays for the sensitization of large band gap semiconductors. Details of this work are provided in the body of the report.

  12. Interplay of metal-allyl and metal-metal bonding in dimolybdenum allyl complexes

    Energy Technology Data Exchange (ETDEWEB)

    John, Kevin D [Los Alamos National Laboratory; Martin, Richard L [Los Alamos National Laboratory; Obrey, Steven J [Los Alamos National Laboratory; Scott, Brian L [Los Alamos National Laboratory

    2008-01-01

    Addition of PMe{sub 3} to Mo{sub 2}(allyl){sub 4} afforded Mo{sub 2}(allyl){sub 4}(PMe{sub 3}){sub 2}, in which two of the allyl groups adopt an unprecedented {mu}{sub 2{sup -}}{eta}{sup 1}, {eta}{sup 3} bonding mode; theoretical studies elucidate the role sof the {sigma}- and {pi}-donor ligands in the interplay of metal-allyl and metal-metal bonding.

  13. 含贵金属废催化剂的分析%Analysis of Spent Noble Metals Bearing Process Catalysts

    Institute of Scientific and Technical Information of China (English)

    Stephen Cooke; Algis Naujokas; James Lynn

    2007-01-01

    The industry procedures for analysis of spent noble metals bearing catalysts, including the fire assay collection and acid leaching, and their advantages and disadvantages were introduced. The quality control procedures were discussed in detail. They consist of three levels of quality control for the analysis of spent noble metals bearing catalysts: the method quality control, the sample specific quality control and the instrumental quality control. A flow chart detailing both fire assay and leach was given.%介绍了含贵金属废催化剂的工业分析方法,包括试金和湿法浸出分析法及其优缺点,详细地讨论了分析过程中的三级质量控制,包括方法质量控制、样品质量控制及仪器质量控制.给出了试金分析及湿法浸出分析原则流程图.

  14. Molecular Split-Ring Resonators Based on Metal String Complexes

    CERN Document Server

    Shen, Yao; Ai, Qing; Peng, Shie-Ming; Jin, Bih-Yaw

    2014-01-01

    Metal string complexes or extended metal atom chains (EMACs) belong to a family of molecules that consist of a linear chain of directly bonded metal atoms embraced helically by four multidentate organic ligands. These four organic ligands are usually made up of repeating pyridyl units, single-nitrogen-substituted heterocyclic annulenes, bridged by independent amido groups. Here, in this paper, we show that these heterocyclic annulenes are actually nanoscale molecular split-ring resonators (SRRs) that can exhibit simultaneous negative electric permittivity and magnetic permeability in the UV-Vis region. Moreover, a monolayer of self-assembled EMACs is a periodic array of molecular SRRs which can be considered as a negative refractive index material. In the molecular scale, where the quantum-size effect is significant, we apply the tight-binding method to obtain the frequency-dependent permittivity and permeability of these molecular SRRs with their tensorial properties carefully considered.

  15. Polynuclear transition metal complexes with thiocarbohydrazide and dithiocarbamates

    Science.gov (United States)

    Siddiqi, K. S.; Khan, Sadaf; Nami, Shahab A. A.; El-ajaily, M. M.

    2007-07-01

    Sn(tch) 2{MCl 2} 2 was prepared from the precursor Sn(tch) 2 and MCl 2. It was subsequently allowed to react with diethyldithiocarbamate which yielded the trinuclear complexes of the type Sn(tch) 2{M 2(dtc) 4}, where tch = thiocarbohydrazide, M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and dtc = diethyldithiocarbamate. They were characterized on the basis of microanalytical, thermal (TGA/DSC), spectral (IR, UV-vis, EPR, 1H NMR) studies, conductivity measurement and magnetic moment data. On the basis of spectral data a tetrahedral geometry has been proposed for the halide complexes, Sn(tch) 2{MCl 2} 2 except for Cu(II) which exhibits a square planar coordination although the transition metal ion in Sn(tch) 2{M 2(dtc) 4} achieves an octahedral geometry where the dithiocarbamato moiety acts as a symmetrical bidentate ligand. The bidentate nature has been established by the appearance of a sharp single ν(C-S) around 1000 cm -1. A downfield shift observed in NH a and NH b protons on moving from Sn(tch) 2 to Sn(tch) 2{MCl 2} 2 is due to the drift of electrons toward metal atoms. A two-step pyrolysis has been observed in the Sn(tch) 2{MCl 2} 2 complexes while their dithiocarbamato derivatives exhibit a three-stage degradation pattern. Finally, the in vitro antibacterial activity of Sn(tch) 2{M 2(dtc) 4} and the mononuclear Sn(tch) 2 has been carried out on bacterial strains Escherichia coli and Salmonella typhi. The compounds were found to be active against the test organisms. The activity of the complexes is enhanced with increasing concentration. The maximum activity in both the strains was achieved by cobalt(II) dithiocarbamate complex. Minimum activity was found for Sn(tch) 2 which generally increases with the introduction of transition metal ion in the complex.

  16. Transistor-like behavior of transition metal complexes

    DEFF Research Database (Denmark)

    Albrecht, Tim; Guckian, A; Ulstrup, Jens

    2005-01-01

    Electron transport through semiconductor and metallic nanoscale structures,(1) molecular monolayers,2-6 and single molecules(7-15) connected to external electrodes display rectification, switch, and staircase functionality of potential importance in future miniaturization of electronic devices....... Common to most reported systems is, however, ultrahigh vacuum and/or cryogenic working conditions. Here we introduce a single-molecule device concept based on a class of robust redox active transition metal (Os(II)/(III)) complexes inserted between the working electrode and tip in an electrochemical...... the redox level is brought into the energy window between the Fermi levels of the electrodes by the overpotential ("gate voltage"). The current-voltage characteristics for two Os(II)/(III) complexes have been characterized systematically and supported by theoretical frames based on molecular charge...

  17. Dynamic inclusion complexes of metal nanoparticles inside nanocups.

    Science.gov (United States)

    Alarcón-Correa, Mariana; Lee, Tung-Chun; Fischer, Peer

    2015-06-01

    Host-guest inclusion complexes are abundant in molecular systems and of fundamental importance in living organisms. Realizing a colloidal analogue of a molecular dynamic inclusion complex is challenging because inorganic nanoparticles (NPs) with a well-defined cavity and portal are difficult to synthesize in high yield and with good structural fidelity. Herein, a generic strategy towards the fabrication of dynamic 1:1 inclusion complexes of metal nanoparticles inside oxide nanocups with high yield (>70%) and regiospecificity (>90%) by means of a reactive double Janus nanoparticle intermediate is reported. Experimental evidence confirms that the inclusion complexes are formed by a kinetically controlled mechanism involving a delicate interplay between bipolar galvanic corrosion and alloying-dealloying oxidation. Release of the NP guest from the nanocups can be efficiently triggered by an external stimulus. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Tetravalent metal complexation by Keggin and lacunary phosphomolybdate anions.

    Science.gov (United States)

    Copping, Roy; Jonasson, Leif; Gaunt, Andrew J; Drennan, Dennis; Collison, David; Helliwell, Madeleine; Pirttijarvi, Ross J; Jones, Chris J; Huguet, Anne; Apperley, David C; Kaltsoyannis, Nikolas; May, Iain

    2008-07-07

    We report the synthesis, spectroscopic and structural characterization, and computational analysis of a series of phosphomolybdate complexes with tetravalent metal cations. The reaction between Ce (IV) and Th (IV) with phosphomolybdate at the optimum pH for the stabilization of the lacunary heteropolyoxometalate anion, [PMo 11O 39] (7-), results in the formation of compounds containing the anions [Ce(PMo 11O 39) 2] (10-) and [Th(PMo 11O 39) 2] (10-), respectively. Single crystal X-ray diffraction analysis was performed on salts of both species, Cs 10[Ce(PMo 11O 39) 2].20H 2O and (NH 4) 10[Th(PMo 11O 39) 2].22H 2O. In both anionic complexes the f-block metal cation is coordinated to the four unsaturated terminal lacunary site oxygens of each [PMo 11O 39] (7-) anion, yielding 8 coordinate sandwich complexes, analogous to previously prepared related complexes. Spectroscopic characterization points to the stability of these complexes in solution over a reasonably wide pH range. Density functional analysis suggests that the Ce-O bond strength in [Ce(PMo 11O 39) 2] (10-) is greater than the Th-O bond strength in [Th(PMo 11O 39) 2] (10-), with the dominant bonding interaction being ionic in both cases. In contrast, under similar reaction conditions, the dominant solid state Zr (IV) and Hf (IV) complexes formed contain the anions [Zr(PMo 12O 40)(PMo 11O 39)] (6-) and [Hf(PMo 12O 40)(PMo 11O 39)] (6-), respectively. In these complexes the central Group 4 d-block metal cations are coordinated to the four unsaturated terminal lacunary site oxygens of the [PMo 11O 39] (7-) ligand and to four bridging oxygens of a plenary Keggin anion, [PMo 12O 40] (3-). In addition, (NH 4) 5{Hf[PMo 12O 40][(NH 4)PMo 11O 39]}.23.5H 2O can be crystallized as a minor product. The structure of the anion, {Hf[PMo 12O 40][(NH 4)PMo 11O 39]} (5-), reveals coordination of the central Hf (IV) cation via four bridging oxygens on both the coordinated [PMo 11O 39] (7-) and [PMo 12O 40] (3-) anions

  19. Asymmetric Schiff bases derived from diaminomaleonitrile and their metal complexes

    Science.gov (United States)

    Yang, Jianjie; Shi, Rufei; Zhou, Pei; Qiu, Qiming; Li, Hui

    2016-02-01

    Asymmetric Schiff bases, due to its asymmetric structure, can be used as asymmetric catalyst, antibacterial, and mimic molecules during simulate biological processes, etc. In recent years, research on synthesis and properties of asymmetric Schiff bases have become an increase interest of chemists. This review summarizes asymmetric Schiff bases derived from diaminomaleonitrile (DAMN) and DAMN-based asymmetric Schiff bases metal complexes. Applications of DAMN-based asymmetric Schiff bases are also discussed in this review.

  20. POLYMER SUPPORT EFFECTS OF METAL COMPLEXES FOR CATALYSIS

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    In the course of investigating the catalytic behavior of metal complexes for ring opening metathesis polymerization of cycloolefins, metathesis, hydroformylation and selective hydrogenation of olefins experimental results time and again indicate the presence of effects of macromolecular supports--the utilization of macromolecular supports increases obviously the activity, selectivity, and stability of the catalysts and so as to increase the conversion of substrates, yields of reactions, properties of formed polymers and so on. Discussed these effects on the basis of the authors' experiments.

  1. mer and fac isomerism in tris chelate diimine metal complexes.

    Science.gov (United States)

    Dabb, Serin L; Fletcher, Nicholas C

    2015-03-14

    In this perspective, we highlight the issue of meridional (mer) and facial (fac) orientation of asymmetrical diimines in tris-chelate transition metal complexes. Diimine ligands have long been the workhorse of coordination chemistry, and whilst there are now good strategies to isolate materials where the inherent metal centered chirality is under almost complete control, and systematic methodologies to isolate heteroleptic complexes, the conceptually simple geometrical isomerism has not been widely investigated. In systems where the two donor atoms are significantly different in terms of the σ-donor and π-accepting ability, the fac isomer is likely to be the thermodynamic product. For the diimine complexes with two trigonal planar nitrogen atoms there is much more subtlety to the system, and external factors such as the solvent, lattice packing and the various steric considerations play a delicate role in determining the observed and isolable product. In this article we discuss the possibilities to control the isomeric ratio in labile systems, consider the opportunities to separate inert complexes and discuss the observed differences in their spectroscopic properties. Finally we report on the ligand orientation in supramolecular systems where facial coordination leads to simple regular structures such as helicates and tetrahedra, but the ability of the ligand system to adopt a mer orientation enables self-assembled structures of considerable beauty and complexity.

  2. Mono- and Dinuclear Macrocyclic Calcium Complexes as Platforms for Mixed-Metal Complexes and Clusters.

    Science.gov (United States)

    Connolly, Emma A; Leeland, James W; Love, Jason B

    2016-01-19

    Mono- and dinuclear calcium complexes of the Schiff-base macrocycles H4L have been prepared and characterized spectroscopically and crystallographically. In the formation of Ca(THF)2(H2L(1)), Ca2(THF)2(μ-THF)(L(1)), and Ca2(THF)4(L(2)), the ligand framework adopts a bowl-shaped conformation instead of the conventional wedge, Pacman-shaped structure as seen with the anthracenyl-hinged complex Ca2(py)5(L(3)). The mononuclear calcium complex Ca(THF)2(H2L(1)) reacts with various equivalents of LiN(SiMe3)2 to form calcium/alkali metal clusters and dinuclear transition metal complexes when reacted subsequently with transition metal salts. The dinuclear calcium complex Ca2(THF)2(μ-THF)(L(1)), when reacted with various equivalents of NaOH, is shown to act as a platform for the formation of calcium/alkali metal hydroxide clusters, displaying alternate wedged and bowl-shaped conformations.

  3. Metal Complexes And Free Radical Toxins Produced By Pfiesteria Piscicida

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, P.D.R.; Beauchesne, K.R.; Huncik, K.M.; Davis, W.C.; Christopher, S.J.; Riggs-Gelasco, P.; Gelasco, A.K.

    2009-06-03

    Metal-containing organic toxins produced by Pfiesteria piscicida were characterized, for the first time, by corroborating data obtained from five distinct instrumental methods: nuclear magnetic resonance spectroscopy (NMR), inductively coupled plasma mass spectrometry (ICPMS), liquid chromatography particle beam glow discharge mass spectrometry (LC/PB-GDMS), electron paramagnetic resonance spectroscopy (EPR), and X-ray absorption spectroscopy (XAS). The high toxicity of the metal-containing toxins is due to metal-mediated free radical production. This mode of activity explains the toxicity of Pfiesteria, as well as previously reported difficulty in observing the molecular target, due to the ephemeral nature of radical species. The toxins are highly labile in purified form, maintaining activity for only 2-5 days before all activity is lost. The multiple toxin congeners in active extracts are also susceptible to decomposition in the presence of white light, pH variations, and prolonged heat. These findings represent the first formal isolation and characterization of a radical forming toxic organic-ligated metal complex isolated from estuarine/marine dinoflagellates. These findings add to an increased understanding regarding the active role of metals interacting with biological systems in the estuarine environment, as well as their links and implications to human health.

  4. Metal Complexes and Free Radical Toxins Produced by Pfiesteria piscicida

    Energy Technology Data Exchange (ETDEWEB)

    Moeller,P.; Beauchesne, K.; Huncik, K.; Davis, W.; Christopher, S.; Riggs-Gelasco, P.; Gelasco, A.

    2007-01-01

    Metal-containing organic toxins produced by Pfiesteria piscicida were characterized, for the first time, by corroborating data obtained from five distinct instrumental methods: nuclear magnetic resonance spectroscopy (NMR), inductively coupled plasma mass spectrometry (ICP-MS), liquid chromatography particle beam glow discharge mass spectrometry (LC/PB-GDMS), electron paramagnetic resonance spectroscopy (EPR), and X-ray absorption spectroscopy (XAS). The high toxicity of the metal-containing toxins is due to metal-mediated free radical production. This mode of activity explains the toxicity of Pfiesteria, as well as previously reported difficulty in observing the molecular target, due to the ephemeral nature of radical species. The toxins are highly labile in purified form, maintaining activity for only 2-5 days before all activity is lost. The multiple toxin congeners in active extracts are also susceptible to decomposition in the presence of white light, pH variations, and prolonged heat. These findings represent the first formal isolation and characterization of a radical forming toxic organic-ligated metal complex isolated from estuarine/marine dinoflagellates. These findings add to an increased understanding regarding the active role of metals interacting with biological systems in the estuarine environment, as well as their links and implications to human health.

  5. Protection of metal artefacts with the formation of metal-oxalates complexes by Beauveria bassiana.

    Directory of Open Access Journals (Sweden)

    Edith eJoseph

    2012-01-01

    Full Text Available Several fungi present high tolerance to toxic metals and some are able to transform metals into metal-oxalate complexes. In this study, the ability of Beauveria bassiana to produce copper oxalates was evaluated in vitro. Growth performance was tested on various copper-containing media. B. bassiana proved highly resistant to copper, tolerating concentrations of up to 20 g.L-1, and precipitating copper oxalates on all media tested. Chromatographic analyses showed that this species produced oxalic acid as sole metal chelator. The production of metal-oxalates can be used in the restoration and conservation of archaeological and modern metal artefacts. The production of copper-oxalates was confirmed directly using metallic pieces (both archaeological and modern. The conversion of corrosion products into copper oxalates was demonstrated as well. In order to assess whether the capability of B. bassiana to produce metal-oxalates could be applied to other metals, iron and silver were tested as well. Iron appears to be directly sequestered in the wall of the fungal hyphae forming oxalates and probably goethite. However, the formation of a homogeneous layer on the object is not yet optimal. Silver nitrate was extracellularly reduced into nanoparticles of elemental silver by an unknown mechanism. The production of copper oxalates is immediately applicable for the conservation of copper-based artefacts. For iron and silver this is not yet the case. However, the vast ability of B. bassiana to transform toxic metals using different immobilization mechanisms seems to offer considerable possibilities for industrial applications, such as the bioremediation of contaminated soils or the green synthesis of chemicals.

  6. Cationic gold(I) heteroleptic complexes bearing a pyrazole-derived N-heterocyclic carbene: syntheses, characterizations, and cytotoxic activities.

    Science.gov (United States)

    Sivaram, Haresh; Tan, Jackie; Huynh, Han Vinh

    2013-09-14

    A series of cationic gold(I) heteroleptic complexes bearing the pyrazole-derived N-heterocyclic carbene (NHC) FPyr (1,2,3,4,6,7,8,9-octahydropyridazino[1,2-a]indazolin-11-ylidene), and either a 1,3-disubstituted benzimidazole-derived NHC of the type RR'-bimy (3: R = R' = CHPh2; 4: R = CHPh2, R' = (i)Pr; 5: R = R' = CH2Ph; 6: R = R' = (i)Bu; 7: R = R' = n-Pr; 8: R = R' = Et; 9: R = R' = 2-propenyl) or a non-NHC co-ligand L (10: L = PPh3; 11: L = P(OPh)3; 12: L = DMAP) (DMAP = 4-dimethylaminopyridine) have been synthesized from [AuCl(FPyr)] (1). Complexes 3-12 have been characterized using multinuclei NMR spectroscopies, ESI mass spectrometry, and elemental analysis. X-ray diffraction analyses have been performed on complexes 5, 6, and 9-11. To the best of our knowledge, 11 represents the first gold-NHC complex to bear the P(OPh)3 ligand. The cytotoxic activities of complexes 3-12 have been studied in vitro with the NCI-H1666 non-small cell lung cancer cell line.

  7. Intraparticulate Metal Speciation Analysis of Soft Complexing Nanoparticles. The Intrinsic Chemical Heterogeneity of Metal-Humic Acid Complexes

    DEFF Research Database (Denmark)

    Town, R. M.; van Leeuwen, Herman P.

    2016-01-01

    ion condensation potential for higher valency counterions within the intraparticulate double layer zone of the soft NP. The approach offers new insights into the intrinsic heterogeneity of the HA. complexes, as revealed by the intraparticulate speciation as a function of the true degree of inner......The counterion condensation-Dorman (CCD) model for the electrostatic features of soft, charged nanopartides (NPs) is applied to the determination of the intrinsic stability constants, kit, for inner-sphere Cd(II) and Cu(II) complexes with humic acid NPs. The novel CCD model accounts for the strong......-sphere complexation, theta(M). The ensuing intrinsic heterogeneity parameters, Gamma, for CdHA and CuHA complexes are in very good agreement with those obtained from dynamic electrochemical stripping chronopotentiometric measurements. The overall intraparticulate metal ion speciation is found to depend on theta...

  8. Kinetic and Thermodynamic Stabilization of Metal Complexes by Introverted Coordination in a Calix[6]azacryptand.

    Science.gov (United States)

    Inthasot, Alex; Brunetti, Emilio; Lejeune, Manuel; Menard, Nicolas; Prangé, Thierry; Fusaro, Luca; Bruylants, Gilles; Reinaud, Olivia; Luhmer, Michel; Jabin, Ivan; Colasson, Benoit

    2016-03-24

    The Huisgen thermal reaction between an organic azide and an acetylene was employed for the selective monofunctionalization of a X6 -azacryptand ligand bearing a tren coordinating unit [X6 stands for calix[6]arene and tren for tris(2-aminoethyl)amine]. Supramolecular assistance, originating from the formation of a host-guest inclusion complex between the reactants, greatly accelerates the reaction while self-inhibition affords a remarkable selectivity. The new ligand possesses a single amino-leg appended at the large rim of the calixarene core and the corresponding Zn(2+) complex was characterized both in solution and in the solid state. The coordination of Zn(2+) not only involves the tren cap but also the introverted amino-leg, which locks the metal ion in the cavity. Compared with the parent ligand deprived of the amino-leg, the affinity of the new monofunctionalized X6 tren ligand 6 for Zn(2+) is found to have a 10-fold increase in DMSO, which is a very competitive solvent, and with an enhancement of at least three orders of magnitude in CDCl3 /CD3 OD (1:1, v/v). In strong contrast with the fast binding kinetics, decoordination of Zn(2+) as well as transmetallation appeared to be very slow processes. The monofunctionalized X6 tren ligand 6 fully protects the metal ion from the external medium thanks to the combination of a cavity and a closed coordination sphere, leading to greater thermodynamic and kinetic stabilities.

  9. Late transition metal m-or chemistry and D6 metal complex photoeliminations

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, Paul [Univ. of Missouri, Columbia, MO (United States)

    2015-07-31

    With the goal of understanding and controlling photoreductive elimination reactions from d6 transition metal complexes as part of a solar energy storage cycle we have investigated the photochemistry of Pt(IV) bromo, chloro, hydroxo, and hydroperoxo complexes. Photoreductive elimination reactions occur for all of these complexes and appear to involve initial Pt-Br, Pt-Cl, or Pt-O bond fission. In the case of Pt-OH bond fission, the subsequent chemistry can be controlled through hydrogen bonding to the hydroxo group.

  10. Metal complexes as antibacterial agents: Synthesis, characterization and antibacterial activity of some 3d metal complexes of sulphadimidine

    Directory of Open Access Journals (Sweden)

    Adedibu Clement Tella

    2010-06-01

    Full Text Available Metal complexes of Sulphadimidine(SAD were synthesized.The complexes were formulated as [Co(SAD2Cl2], [Cu(SAD2 (H2O2], [Ni (SAD2 Cl2 H2O], [Cd (SAD2 Br2], [Fe (SAD3](H­2O­3 and [Mn (SAD2Cl2] characterized by elemental Analysis, conductivity, IR , UV-Vis, Magnet moment and 1H-NMR and Mass spectroscopies. Co(II, Mn (II,  and Ni(II sulphadimidine complexes consist of metal ion which coordinates through amino nitrogen of the terminal NH2 group and oxygen of sulfonamidic group of the two molecules of sulphadimidine ligand and two halide ions to form octahedral structure while Cd(II coordinates with sulphadimidine through amino nitrogen of the terminal NH2 group with two bromine ions to complete tetrahedral structure. In Cu(II sulphadimidine complex, copper ion coordinates through both pyrimidinic nitrogen (heterocyclic nitrogen and sulfonamidic nitrogen of the two molecules of sulphadimidine. Fe(III coordinates to three molecules of sulphadimidine through heterocyclic nitrogen (pyrimidinic nitrogen and sulfonamidic nitrogen,with three molecules of water outside the coordination sphere. Both Fe(III and Cu(II complexes exhibit octahedral geometry. The antibacterial activity of the complexes and the ligands was investigated against Esherichia coli,  Staphylococcus aureus and Klebsiella pneumonia .  The data obtained revealed that the complexes showed greater activity against the three micro-organisms when compared to parent compound. Stability constant of the complexes were evaluated for the metal salts, the order of stability constant b was found to be Cu (II > Fe (III >Ni(II> Co (II > Cd (II.The values of stability constant (b was found to be log 6.31, 5.93, 5.29, 4.63 and 3.92, respectively. The stability constant data revealed that this ligand may be used as antidote or chelating agent for medical treatment of metals overload or poisoning.

  11. Synthesis and cytotoxic activity of metallic complexes of lawsone.

    Science.gov (United States)

    Oramas-Royo, Sandra; Torrejón, Concepción; Cuadrado, Irene; Hernández-Molina, Rita; Hortelano, Sonsoles; Estévez-Braun, Ana; de Las Heras, Beatriz

    2013-05-01

    In the present study, a series of metallic complexes of the 1,4-naphthoquinone lawsone (2-6) were synthesized and evaluated for potential cytotoxicity in a mouse leukemic macrophagic RAW 264.7 cell line. Cell viability was determined by the MTT assay. Significant growth inhibition was observed for the copper complex (4) with an IC(50) value of 2.5 μM. This compound was selected for further evaluation of cytotoxic activity on several human cancer cells including HT-29 (human colorectal adenocarcinoma), HepG2 (human hepatocellular carcinoma) and HeLa, (human cervical adenocarcinoma cells). Significant cell viability decrease was also observed in HepG2 cells. The apoptotic potential of this complex was evaluated in these cells. Compound 4 induced apoptosis by a mechanism that involves the activation of caspases 3, 8 and 9 and modulation of apoptotic-related proteins such as Bax, Bad, and p53. These results indicate that metal complexes of lawsone derivatives, in particular compound 4, might be used for the design of new antitumoral agents. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Unmetallated and metallated phthalocyanines bearing oxadiazole groups: Synthesis, photophysical and photochemical studies

    Energy Technology Data Exchange (ETDEWEB)

    Nas, Asiye [Department of Chemistry, Karadeniz Technical University, 61080 Trabzon (Turkey); Kantekin, Halit, E-mail: halit@ktu.edu.tr [Department of Chemistry, Karadeniz Technical University, 61080 Trabzon (Turkey); Durmuş, Mahmut [Gebze Institute of Technology, Department of Chemistry, PO Box 141, Gebze, 41400 Kocaeli (Turkey); Gümrükçüoğlu, Nurhan [Department of Chemistry, Karadeniz Technical University, 61080 Trabzon (Turkey)

    2014-10-15

    Unmetallated (4) and metallated (zinc(II), cobalt(II), lead(II)) phthalocyanines (5–7) carrying four 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy) groups on the peripheral positions were synthesized by cyclotetramerization of 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy)phthalonitrile (3) in the presence of corresponding metal salts (zinc(II) acetate, cobalt(II) chloride, lead(II) oxide) for metallated and without any metal for unmetallated phthalocyanines. The obtained organo-soluble phthalocyanines were characterized by infrared, electronic absorption, nuclear magnetic resonance and mass spectral techniques and elemental analysis as well. The photophysical and photochemical properties of newly synthesized tetra-substituted unmetallated (4), zinc(II) (5) and lead(II) (7) phthalocyanines were reported in N,N-dimetilformamid (DMF). The synthesized phthalocyanine compound 6 was not evaluated for photophysical and photochemical studies due to open shell and paramagnetic behavior of cobalt(II) metal ions in the phthalocyanine cavity. - Highlights: • Synthesis of unmetallated and metallated phthalocyanines. • Photophysical and photochemical properties of tetra-substituted phthalocyanines. • Characterization of organosoluble phthalocyanines by several spectral techniques.

  13. STUDY ON SYNTHESIS AND RELAXIVITY OF PARAMAGNETIC POLYESTER METAL COMPLEXES FOR MRI

    Institute of Scientific and Technical Information of China (English)

    Ouyangming; ZhuoRenxi; 等

    1995-01-01

    Fifteen new polyester ligands were prepared by copolymerization of EDTA (ethylenediaminetertraacetic acid)dianhydride or DTPA (diethylenetriamine pentaacetic acid) dianhydride and dihydric alcohol or dihydric phenol.Their paramagnetic metal complexes were also synthesized.All polyester ligands and metal complexes were characterized by 1HNMR,IR spectra and elemental analyses.Preliminary study showed that the polyester metal complexes had higher relaxation effectiveness as compared to corresponding small molecular metal complexes.

  14. Supramolecular structures constructed from three novel rare earth metal complexes

    Indian Academy of Sciences (India)

    Huaze Dong; Xiaojun Feng; Xia Liu; BiN Zheng; Jianhong Bi; Yan Xue; Shaohua Gou; Yanping Wang

    2015-05-01

    Three rare earth metal supramolecular complexes, {[Tb(2)4](ClO4)3·2H2O(1), [Eu(2)2(H2O)5] (ClO4)3(2) and [Gd(NO3)3(2)2]·2CH3CH2OH(3) ( 2 = 3-Dimethylamino-1-pyridin-2-yl-propenone), have been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction. The crystal structure analysis reveals that the coordination numbers of three complexes (1–3) are 8, 9 and 10, respectively. Three complexes assembled into 3D frameworks based on C-H⋯O, O-H⋯O hydrogen bond linkages.

  15. Infrared Spectroscopy of Metal Ion Complexes: Models for Metal Ligand Interactions and Solvation

    Science.gov (United States)

    Duncan, Michael

    2006-03-01

    Weakly bound complexes of the form M^+-Lx (M=Fe, Ni, Co, etc.; L=CO2, C2H2, H2O, benzene, N2) are prepared in supersonic molecular beams by laser vaporization in a pulsed-nozzle cluster source. These species are mass analyzed and size-selected in a reflectron time-of-flight mass spectrometer. Clusters are photodissociated at infrared wavelengths with a Nd:YAG pumped infrared optical parametric oscillator/amplifier (OPO/OPA) laser or with a tunable infrared free-electron laser. M^+-(CO2)x complexes absorb near the free CO2 asymmetric stretch near 2349 cm-1 but with an interesting size dependent variation in the resonances. Small clusters have blue-shifted resonances, while larger complexes have additional bands due to surface CO2 molecules not attached to the metal. M^+(C2H2)n complexes absorb near the C-H stretches in acetylene, but resonances in metal complexes are red-shifted with repect to the isolated molecule. Ni^+ and Co^+ complexes with acetylene undergo intracluster cyclization reactions to form cyclobutadiene. Transition metal water complexes are studied in the O-H stretch region, and partial rotational structure can be measured. M^+(benzene) and M^+(benzene)2 ions (M=V, Ti, Al) represent half-sandwich and sandwich species, whose spectra are measured near the free benzene modes. These new IR spectra and their assignments will be discussed as well as other new IR spectra for similar complexes.

  16. Identification of metal species by ESI-MS/MS through release of free metals from the corresponding metal-ligand complexes.

    Science.gov (United States)

    Tsednee, Munkhtsetseg; Huang, Yu-Chen; Chen, Yet-Ran; Yeh, Kuo-Chen

    2016-05-31

    Electrospray ionization-mass spectrometry (ESI-MS) is used to analyze metal species in a variety of samples. Here, we describe an application for identifying metal species by tandem mass spectrometry (ESI-MS/MS) with the release of free metals from the corresponding metal-ligand complexes. The MS/MS data were used to elucidate the possible fragmentation pathways of different metal-deoxymugineic acid (-DMA) and metal-nicotianamine (-NA) complexes and select the product ions with highest abundance that may be useful for quantitative multiple reaction monitoring. This method can be used for identifying different metal-ligand complexes, especially for metal species whose mass spectra peaks are clustered close together. Different metal-DMA/NA complexes were simultaneously identified under different physiological pH conditions with this method. We further demonstrated the application of the technique for different plant samples and with different MS instruments.

  17. Complex intermetallic phase in multicrystalline silicon doped withtransition metals

    Energy Technology Data Exchange (ETDEWEB)

    Heuer, Matthias; Buonassisi, Tonio; Marcus, Matthew A.; Istratov,Andrei A.; Pickett, Matthew D.; Shibata, Tomohiro; Weber, Eicke R.

    2006-01-01

    We report the observation of an alloy phase with fluorite-type structure containing Ni, Fe, Cu, and Si, found as precipitates in multi-crystalline silicon. The analysis of extended x-ray absorption fine-structure microspectroscopy ({micro}-EXAFS) measurements on the K edges of the transition metals of the precipitates and a synthetic reference material with composition of Ni{sub 0.82}Fe{sub 0.21}Cu{sub 0.02}Si{sub 1.94} support a structure model similar to NiSi{sub 2} but with mixed occupancies of Fe on the Ni site and Cu on the Si site. This observation provides evidence that transition metals interact during precipitation within silicon and form complex silicides.

  18. Complex metal borohydrides: multifunctional materials for energy storage and conversion.

    Science.gov (United States)

    Mohtadi, Rana; Remhof, Arndt; Jena, Puru

    2016-09-07

    With the limited supply of fossil fuels and their adverse effect on the climate and the environment, it has become a global priority to seek alternate sources of energy that are clean, abundant, and sustainable. While sources such as solar, wind, and hydrogen can meet the world's energy demand, considerable challenges remain to find materials that can store and/or convert energy efficiently. This topical review focuses on one such class of materials, namely, multi-functional complex metal borohydrides that not only have the ability to store sufficient amount of hydrogen to meet the needs of the transportation industry, but also can be used for a new generation of metal ion batteries and solar cells. We discuss the material challenges in all these areas and review the progress that has been made to address them, the issues that still need to be resolved and the outlook for the future.

  19. Complex metallic alloys as new materials for additive manufacturing.

    Science.gov (United States)

    Kenzari, Samuel; Bonina, David; Marie Dubois, Jean; Fournée, Vincent

    2014-04-01

    Additive manufacturing processes allow freeform fabrication of the physical representation of a three-dimensional computer-aided design (CAD) data model. This area has been expanding rapidly over the last 20 years. It includes several techniques such as selective laser sintering and stereolithography. The range of materials used today is quite restricted while there is a real demand for manufacturing lighter functional parts or parts with improved functional properties. In this article, we summarize recent work performed in this field, introducing new composite materials containing complex metallic alloys. These are mainly Al-based quasicrystalline alloys whose properties differ from those of conventional alloys. The use of these materials allows us to produce light-weight parts consisting of either metal-matrix composites or of polymer-matrix composites with improved properties. Functional parts using these alloys are now commercialized.

  20. Complex metal borohydrides: multifunctional materials for energy storage and conversion

    Science.gov (United States)

    Mohtadi, Rana; Remhof, Arndt; Jena, Puru

    2016-09-01

    With the limited supply of fossil fuels and their adverse effect on the climate and the environment, it has become a global priority to seek alternate sources of energy that are clean, abundant, and sustainable. While sources such as solar, wind, and hydrogen can meet the world’s energy demand, considerable challenges remain to find materials that can store and/or convert energy efficiently. This topical review focuses on one such class of materials, namely, multi-functional complex metal borohydrides that not only have the ability to store sufficient amount of hydrogen to meet the needs of the transportation industry, but also can be used for a new generation of metal ion batteries and solar cells. We discuss the material challenges in all these areas and review the progress that has been made to address them, the issues that still need to be resolved and the outlook for the future.

  1. High load-bearing multi-material-joints of metal sheets and composites by incremental in-situ forming processes

    Science.gov (United States)

    Seidlitz, Holger; Fritzsche, Sebastian; Bambach, Markus; Gerstenberger, Colin

    2016-10-01

    Thermo-mechanically flow-formed joints (FDJ) are an appropriate joining technology to realize high load-bearing multi-material-joints between fiber reinforced thermoplastics and sheet metals, without additional joining components. As in the automotive industry new vehicle and lightweight designs with one-sided accessibility joints are required, the technology which so far requires a two-sided accessibility of the joint, is examined for the ability to be performed with one-sided accessibility. The main part of the paper are therefore experimental studies on the one-sided manufacturing of FDJ-joints without an additional forming tool and their examination with head pull test and tension shear test according to DIN EN ISO 14272 and DIN EN ISO 14273. In this context, a tool and an experimental setup were designed to provide a corresponding joint production of a material combination of continuous glass fiber reinforced polypropylene (Plytron) and an aluminum alloy (EN AW-6082 T6). In the experiment, the novel joints bear maximum forces of 291 N in the head pull test and 708 N in the tension shear test.

  2. Electrochemical corrosion of a noble metal-bearing alloy-oxide composite

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X; Ebert, W. L.; Indacochea, Ernesto

    2017-08-01

    The effects of added Ru and Pd on the microstructure and electrochemical behaviour of a composite material made by melting those metals with AISI 410 stainless steel, Zr, Mo, and lanthanide oxides were assessed using electrochemical and microscopic methods The lanthanide oxides reacted with Zr to form durable lanthanide zirconates and Mo alloyed with steel to form FeMoCr intermetallics. The noble metals alloyed with the steel to provide solid solution strengthening and inhibit carbide/nitride formation. A passive film formed during electrochemical tests in acidic NaCl solution, but became less effective as corrosion progressed and regions over the intermetallics eventually failed.

  3. Chemistry and Properties of Complex Intermetallics from Metallic Fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Kanatzidis, Mercouri G. [Northwestern Univ., Evanston, IL (United States)

    2015-03-28

    This project investigated the reaction chemistry and synthesis of new intermetallic materials with complex compositions and structures using metallic fluxes as solvents. It was found that the metallic fluxes offer several key advantages in facilitating the formation and crystal growth of new materials. The fluxes mostly explored were liquid aluminum, gallium and indium. The main purpose of this project was to exploit the potential of metallic fluxes as high temperature solvent for materials discovery in the broad class of intermetallics. This work opened new paths to compound formation. We discovered many new Si (or Ge)-based compounds with novel structures, bonding and physicochemical properties. We created new insights about the reaction chemistry that is responsible for stabilizing the new materials. We also studied the structural and compositional relationships to understand their properties. We investigated the use of Group-13 metals Al, Ga and In as solvents and have generated a wide variety of new results including several new ternary and quaternary materials with fascinating structures and properties as well as new insights as to how these systems are stabilized in the fluxes. The project focused on reactions of metals from the rare earth element family in combination with transition metals with Si and Ge. For example molten gallium has serves both as a reactive and non-reactive solvent in the preparation and crystallization of intermetallics in the system RE/M/Ga/Ge(Si). Molten indium behaves similarly in that it too is an excellent reaction medium, but it gives compounds that are different from those obtained from gallium. Some of the new phase identified in the aluminide class are complex phases and may be present in many advanced Al-matrix alloys. Such phases play a key role in determining (either beneficially or detrimentally) the mechanical properties of advanced Al-matrix alloys. This project enhanced our basic knowledge of the solid state chemistry

  4. Synthesis and luminescence of some rare earth metal complexes

    Science.gov (United States)

    Bochkarev, Mikhail N.; Pushkarev, Anatoly P.

    2016-12-01

    In the present paper the synthesis, photoand electroluminescent properties of new rare earth metal complexes prepared and studied at the Razuvaev Institute of Organometallic Chemistry during the last decade are reviewed. The obtained compounds give luminescence in UV, visible and NIR regions. The substituted phenolates, naphtholates, mercaptobenzothiazolate, 8-oxyquinolinolate, polyfluorinated alcoholates and chalcogenophosphinates were used as ligands. The synthesis and structure of unusual three-nuclear sulfidenitride clusters of Nd and Dy are described. The new excitation mechanism of ytterbium phenolates and naphtholates, which includes the stage of reversible reduction of Yb to divalent state and oxidation of the ligands in the excitation process, is discussed.

  5. The DNA-binding and bioactivity of rare earth metal complexes.

    Science.gov (United States)

    Yang, Li; Wang, Bochu; Tan, Jun; Zhu, Liancai

    2013-08-01

    Recently more and more attention is paid to the rare earth metal complexes, because the properties of the rare earth metals are similar to those of the transition metals such as the similar atomic and the ionic radius. A large number of rare metal complexes were synthesized, and their bioactivities were also studied. This review highlights recent researches on the interaction of some rare earth metal complexes with DNA, analyzes how the configuration of the complexes influences the binding affinity, and focuses on the pharmacological activities of the complexes, such as anticancer, antibacterial, antioxidant, anti-inflammatory and anti-virus.

  6. Antioxidant activity of bovine serum albumin binding amino acid Schiff-bases metal complexes

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Glutamic acid-salicylaldehyde Schiff-base metal complexes are bound into bovine serum albumin (BSA), which afforded BSA binding Schiff-base metal complexes (BSA-SalGluM, M=Cu, Co, Ni, Zn). The BSA binding metal complexes were characterized by UV-vis spectra and Native PAGE. It showed that the protein structures of BSA kept after coordinating amino acid Schiff-bases metal complexes. The effect of the antioxidant activity was investigated. The results indicate that the antioxidant capacity of BSA increased more than 10 times after binding Schiff-base metal complexes.

  7. Complexing agent and heavy metal removals from metal plating effluent by electrocoagulation with stainless steel electrodes.

    Science.gov (United States)

    Kabdaşli, Işik; Arslan, Tülin; Olmez-Hanci, Tuğba; Arslan-Alaton, Idil; Tünay, Olcay

    2009-06-15

    In the present study, the treatability of a metal plating wastewater containing complexed metals originating from the nickel and zinc plating process by electrocoagulation using stainless steel electrodes was experimentally investigated. The study focused on the effect of important operation parameters on electrocoagulation process performance in terms of organic complex former, nickel and zinc removals as well as sludge production and specific energy consumption. The results indicated that increasing the applied current density from 2.25 to 9.0 mA/cm(2) appreciably enhanced TOC removal efficiency from 20% to 66%, but a further increase in the applied current density to 56.25 mA/cm(2) did not accelerate TOC removal rates. Electrolyte concentration did not affect the process performance significantly and the highest TOC reduction (66%) accompanied with complete heavy metal removals were achieved at the original chloride content ( approximately 1500 mg Cl/L) of the wastewater sample. Nickel removal performance was adversely affected by the decrease of initial pH from its original value of 6. Optimum working conditions for electrocoagulation of metal plating effluent were established as follows: an applied current density of 9 mA/cm(2), the effluent's original electrolyte concentration and pH of the composite sample. TOC removal rates obtained for all electrocoagulation runs fitted pseudo-first-order kinetics very well (R(2)>92-99).

  8. Preparation and Catalytic Properties of Polymer Supported Dendritic Metal Complex

    Institute of Scientific and Technical Information of China (English)

    LI Cui-ling; YANG Zhi-wang; KANG Qiao-xiang; MA Heng-chang; MA Xiao-peng; GAO Qi-kuan; GUO Zhen; LEI Zi-qiang

    2004-01-01

    Polymer supported materials are extensively used as oxidizing agent, reducing agent catalysts, photosensitizers ion exchange resins and agriculturally and pharmacologically active agents1. The application of polymer metal complexes has been widely investigated2. The polymer supported complex undergoes swelling in a suitable solvent medium and provides enough surface area in carrying out electron transfer reactions, which clearly emphasizes the influence of a polymer network in heterogeneous catalysis.In the present, we have succeeded in the grafting of "dendrimer-like" hyperbranched polymer onto the surface of chloromethyl polystyrene reactions.All the catalysts show promising catalytic activities for the oxidation of iso-propylbenzene in the mild reaction condition, in each case, hypnone 1, 2-phenyl-2-propanol 2 were obtained as the major products

  9. Fluoroquinolone-metal complexes: a route to counteract bacterial resistance?

    Science.gov (United States)

    Feio, Maria J; Sousa, Isabel; Ferreira, Mariana; Cunha-Silva, Luís; Saraiva, Raúl G; Queirós, Carla; Alexandre, José G; Claro, Vasco; Mendes, Adélia; Ortiz, Rosa; Lopes, Sandra; Amaral, Ana Luísa; Lino, João; Fernandes, Patrícia; Silva, Ana João; Moutinho, Lisete; de Castro, Baltazar; Pereira, Eulália; Perelló, Lourdes; Gameiro, Paula

    2014-09-01

    Microbial resistance to antibiotics is one of the biggest public health threats of the modern world. Antibiotic resistance is an area of much clinical relevance and therefore research that has the potential to identify agents that may circumvent it or treat resistant infections is paramount. Solution behavior of various fluoroquinolone (FQ) complexes with copper(II) in the presence and absence of 1,10-phenanthroline (phen) was studied in aqueous solution, by potentiometry and/or spectrophotometry, and are herein described. The results obtained showed that under physiological conditions (micromolar concentration range and pH7.4) only copper(II):FQ:phen ternary complexes are stable. Hence, these complexes were synthesised and characterised by means of UV-visible and IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. In these complexes, the FQ acts as a bidentate ligand that coordinates the metal cation through the carbonyl and carboxyl oxygen atoms and phen coordinates through two N-atoms forming the equatorial plane of a distorted square-pyramidal geometry. The fifth position of the penta-coordinated Cu(II) centre is generally occupied axially by an oxygen atom from a water molecule or from a nitrate ion. Minimum inhibitory concentration (MIC) determinations of the complexes and comparison with free FQ in various E. coli strains indicate that the Cu-complexes are as efficient antimicrobials as the free antibiotic. Moreover, results strongly suggest that the cell intake route of both species is different supporting, therefore, the complexes' suitability as candidates for further biological testing in FQ-resistant microorganisms.

  10. Dual chirality control of palladium(II) complexes bearing tropos biphenyl diamine ligands.

    Science.gov (United States)

    Aikawa, Kohsuke; Mikami, Koichi

    2005-12-14

    Axial and center chirality of Pd complexes with tropos biphenyl secondary diamine ligands is shown to be controlled by chiral amide (R)-DABNTf, which can efficiently discriminate between two enantiomeric Pd complexes.

  11. Simulation of the mobility of metal - EDTA complexes in groundwater: The influence of contaminant metals

    Science.gov (United States)

    Friedly, J.C.; Kent, D.B.; Davis, J.A.

    2002-01-01

    Reactive transport simulations were conducted to model chemical reactions between metal - EDTA (ethylenediaminetetraacetic acid) complexes during transport in a mildly acidic quartz - sand aquifer. Simulations were compared with the results of small-scale tracer tests wherein nickel-, zinc-, and calcium - EDTA complexes and free EDTA were injected into three distinct chemical zones of a plume of sewage-contaminated groundwater. One zone had a large mass of adsorbed, sewage-derived zinc; one zone had a large mass of adsorbed manganese resulting from mildly reducing conditions created bythe sewage plume; and one zone had significantly less adsorbed manganese and negligible zinc background. The chemical model assumed that the dissolution of iron(III) from metal - hydroxypolymer coatings on the aquifer sediments by the metal - EDTA complexes was kinetically restricted. All other reactions, including metal - EDTA complexation, zinc and manganese adsorption, and aluminum hydroxide dissolution were assumed to reach equilibrium on the time scale of transport; equilibrium constants were either taken from the literature or determined independently in the laboratory. A single iron(III) dissolution rate constant was used to fit the breakthrough curves observed in the zone with negligible zinc background. Simulation results agreed well with the experimental data in all three zones, which included temporal moments derived from breakthrough curves at different distances downgradient from the injections and spatial moments calculated from synoptic samplings conducted at different times. Results show that the tracer cloud was near equilibrium with respect to Fe in the sediment after 11 m of transport in the Zn-contaminated region but remained far from equilibrium in the other two zones. Sensitivity studies showed that the relative rate of iron(III) dissolution by the different metal - EDTA complexes was less important than the fact that these reactions are rate controlled. Results

  12. Simulation of the mobility of metal-EDTA complexes in groundwater: the influence of contaminant metals.

    Science.gov (United States)

    Friedly, J C; Kent, D B; Davis, J A

    2002-02-01

    Reactive transport simulations were conducted to model chemical reactions between metal-EDTA (ethylenediaminetetraacetic acid) complexes during transport in a mildly acidic quartz-sand aquifer. Simulations were compared with the results of small-scale tracer tests wherein nickel-, zinc-, and calcium-EDTA complexes and free EDTA were injected into three distinct chemical zones of a plume of sewage-contaminated groundwater. One zone had a large mass of adsorbed, sewage-derived zinc; one zone had a large mass of adsorbed manganese resulting from mildly reducing conditions created by the sewage plume; and one zone had significantly less adsorbed manganese and negligible zinc background. The chemical model assumed that the dissolution of iron(III) from metal-hydroxypolymer coatings on the aquifer sediments by the metal-EDTA complexes was kinetically restricted. All other reactions, including metal-EDTA complexation, zinc and manganese adsorption, and aluminum hydroxide dissolution were assumed to reach equilibrium on the time scale of transport; equilibrium constants were either taken from the literature or determined independently in the laboratory. A single iron(III) dissolution rate constant was used to fit the breakthrough curves observed in the zone with negligible zinc background. Simulation results agreed well with the experimental data in all three zones, which included temporal moments derived from breakthrough curves at different distances downgradient from the injections and spatial moments calculated from synoptic samplings conducted at different times. Results show that the tracer cloud was near equilibrium with respect to Fe in the sediment after 11 m of transport in the Zn-contaminated region but remained far from equilibrium in the other two zones. Sensitivity studies showed that the relative rate of iron(III) dissolution by the different metal-EDTA complexes was less important than the fact that these reactions are rate controlled. Results suggest that

  13. Copper complexes bearing 2-aminobenzothiazole derivatives as potential antioxidant: Synthesis, characterization.

    Science.gov (United States)

    Joseph, J; Janaki, G Boomadevi

    2016-09-01

    Novel copper complexes of Schiff base ligands of 2-aminobenzothiazole derivatives were synthesized by the condensation of Knoevenagel condensate of acetoacetanilide (obtained from substituted benzaldehydes and acetoacetanilide) and 2-aminobenzothiazole. They were characterized by elemental analysis, IR, (1)H NMR, UV-Vis., molar conductance, magnetic susceptibility measurements and electrochemical studies. Based on the magnetic moment and electronic spectral data, square planar geometry has been suggested for all the complexes. Antibacterial and antifungal screening of the ligands and their complexes reveal that all the complexes show higher activities than the ligands. The binding behaviour of the complexes with calf thymus DNA has been investigated by electronic absorption spectra, viscosity measurements and cyclic voltammetry. The DNA binding constants reveal that all these complexes interact with DNA through intercalation binding mode. Superoxide dismutase and antioxidant activities of the copper complexes have also been studied. The antioxidant activities of the complexes showed higher activities. Thermal denaturation studies suggested the nature binding affinity of copper complexes with CT-DNA. All complexes exhibit suitable Cu(II)/Cu(I) redox potential to act as antioxidant enzymes mimic. Further, the copper complexes also showed catalase activity. It is hope that copper complexes were capable of decrease ROS levels or reduce oxidative stress in Alzheimer's patients.

  14. Stress Analysis of a Three-Layer Metal Composite System of Bearing Assemblies During Grinding

    Science.gov (United States)

    Pashnyov, V. A.; Pimenov, D. Yu.

    2015-03-01

    A mathematical model of the stress state of a three-layer metal composite system caused by cutting forces during grinding the working layer of the system is elaborated. The implementation of the model by using the finite-element method made it possible to assess the effect of structure of the system, the deformation properties of layer materials, and grinding conditions on the distribution and level of normal and tangential stresses in layers, which determine the load-carrying capacity of the system. The results of an analysis of stress fields can serve as a basis for determining the grinding conditions ensuring retention of the load-carrying capacity of the metal composite system.

  15. Transistor-like behavior of transition metal complexes.

    Science.gov (United States)

    Albrecht, Tim; Guckian, Adrian; Ulstrup, Jens; Vos, Johannes G

    2005-07-01

    Electron transport through semiconductor and metallic nanoscale structures, molecular monolayers, and single molecules connected to external electrodes display rectification, switch, and staircase functionality of potential importance in future miniaturization of electronic devices. Common to most reported systems is, however, ultrahigh vacuum and/or cryogenic working conditions. Here we introduce a single-molecule device concept based on a class of robust redox active transition metal (Os(II)/(III)) complexes inserted between the working electrode and tip in an electrochemical scanning tunneling microscope (in situ STM). This configuration resembles a single-molecule transistor, where the reference electrode corresponds to the gate electrode. It operates at room temperature in a condensed matter (here aqueous) environment. Amplification on-off ratios up to 50 are found when the redox level is brought into the energy window between the Fermi levels of the electrodes by the overpotential ("gate voltage"). The current-voltage characteristics for two Os(II)/(III) complexes have been characterized systematically and supported by theoretical frames based on molecular charge transport theory.

  16. 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 simi

  17. Crystal structures of two ansa-titanocene tri-fluoro-methane-sulfonate complexes bearing the Me2Si(C5Me4)2 ligand.

    Science.gov (United States)

    Kessler, Monty; Godemann, Christian; Spannenberg, Anke; Beweries, Torsten

    2016-12-01

    The crystal structures of two ansa-titanocene tri-fluoro-methane-sulfonate complexes bearing the Me2Si(C5Me4)2 ligand are reported, namely [di-methylbis-(η(5)-tetra-methyl-cyclo-penta-dien-yl)silane](tri-fluoro-methane-sulfonato-κ(2)O,O')titanium(III) toluene monosolvate, [Ti(CF3O3S)(C20H30Si)]·C7H8, 1, and chlorido-[di-methyl-bis-(η(5)-tetra-methyl-cyclo-penta-dien-yl)silane](tri-fluoro-methane-sulfonato-κO)titanium(IV), [Ti(CF3O3S)(C20H30Si)Cl], 2. Both complexes display a bent metallocene unit, the metal atom being coordinated in a distorted tetra-hedral geometry, with the tri-fluoro-methane-sulfonate anion acting as a bidentate or monodentate ligand in 1 and 2, respectively. In 1, weak π-π stacking inter-actions involving the toluene solvent mol-ecules [centroid-to-centroid distance = 3.9491 (11) Å] are observed.

  18. Lanthanide Single-Molecule Magnets Framed by Alkali Metals & Magnetic and Spectroscopic Studies of 3d Transition Metal Complexes

    DEFF Research Database (Denmark)

    Konstantatos, Andreas

    )imino)- methyl)benzene-1,2-diol]. Using this ligand, we were able to synthesize four different families of lanthanide complexes framed by alkali metals. Throughout the chapter we demonstrate how we can exploit the presence of the coordinated alkali metal ions in order to induce changes to the structure....... In Chapter 3 we present the results of our work with third row (3d) transition metal ions and their complexes. Specifically, in section 2.1 we report a series of complexes synthesized using a tripodal hexadentate Schiff-base ligand. The ligand demonstrates the ability to form mononuclear or trinuclear...... complexes of M3+ or M2+ metal ions (M: 3d transition metal) with the preference to either approximate octahedral or trigonal prismatic coordination geometry. A detailed magnetic characterization for most of the complexes is presented where a trinuclear Co2+ cluster stands out for its pronounced SMM...

  19. Synthesis,structure and catalytic behavior of yttrium complexes bearing a diaminobis(phenolate) ligand

    Institute of Scientific and Technical Information of China (English)

    SONG FengKui; YAN ChunHui; SUN HongMei; YAO YingMing; SHEN Qi; ZHANG Yong

    2009-01-01

    Yttrium complexes stabilized by a diaminobis(phenolate) ligand were synthesized and their catalytic behavior was explored. Reaction of YCI3 with 1 equiv of LNa2 [L=Me2NCH2CH2N{CH2-(2-O-C6H2-tBu2-3,5)}2]gave the yttrium chloride LYCI(THF) (1) in 92% yield. Complex 1 can be used as starting material to prepare the yttrium amido derivative. Complex 1 reacted with 1 equiv of LiNPh2 in THF to afford the expected yttrium amido complex LYNPh2 (2) in high yield. Both of complexes 1 and 2 have been well detected by elemental analysis,NMR spectra and single-crystal X-ray analysis. It was found that complex 2 can efficiently initiate the ring-opening polymerization of L-lactide and ε-caprolactone,and a controlled manner is observed in the former case.

  20. Mineralogical characterization of municipal solid waste incineration bottom ash with an emphasis on heavy metal-bearing phases.

    Science.gov (United States)

    Wei, Yunmei; Shimaoka, Takayuki; Saffarzadeh, Amirhomayoun; Takahashi, Fumitake

    2011-03-15

    Municipal solid waste incineration (MSWI) bottom ash contains a considerable amount of heavy metals. The occurrence and uneven distribution of these heavy metals in bottom ash can increase the complexity of such residues in terms of long-term behavior upon landfilling or recycling. Bottom ashes sampled from three stoker-type incinerators in Japan were analyzed in this paper. This study presents detailed information on the mineralogical characterization of bottom ash constituents and the weathering behavior of these constituents by means of optical microscopy and scanning electron microscopy. It was revealed that bottom ash mainly consists of assorted silicate-based glass phases (48-54 wt% of ash) and mineral phases including melilites, pseudowollastonite, spinels, and metallic inclusions (Fe-P, Fe-S, Fe-Cu, Cu-Sn, Cu-Zn, Cu-S, and Cu-Pb dominated phases), as melt products formed during the incineration process. The compounds embedded in the glass matrix, e.g. spinels and metallic inclusions, played the most important role in concentration of heavy metals (Pb, Zn, Cu, Cr, Mn, Ni, etc.). Other phases such as refractory minerals and ceramics, frequently found in ash, were of less significance in terms of their influence on the involvement of heavy metals. Analysis of lab-scale artificially weathered and 10-year landfilled bottom ash samples revealed that secondary mineralization/alteration of the bottom ash constituents principally carbonation and glass evolution substantially decreased the potential risk of the heavy metals to the surrounding environment. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Studies of Transition Metal Complexes Using Dynamic NMR Techniques.

    Science.gov (United States)

    Coston, Timothy Peter John

    Available from UMI in association with The British Library. This Thesis is primarily concerned with the quantitative study of fluxional processes in, predominantly platinum(IV) complexes, with the ligands 1,1,2,2-tetrakis(methylthio)ethane (MeS)_2CHCH(SMe)_2 , and 1,1,2,2-tetrakis(methylthio)ethene (MeS) _2C=C(SMe)_2. Quantitative information relating to the energetics of these processes has been obtained by a combination of one- and two-dimensional NMR techniques. Chapter One provides an introduction to the background of fluxional processes in transition metal complexes together with data concerning the energetics of the processes that have already been studied by NMR techniques. Chapter Two provides a thorough grounding in NMR techniques, in particular those concerned with the quantitative measurement of rates involved in chemical exchange processes. A description of the use of 2D EXSY NMR spectroscopy in obtaining rate data is given. The properties of the magnetic isotope of platinum are given in Chapter Three. A general survey is also given of some additional compounds that have already been studied by platinum-195 spectroscopy. Chapter Four is concerned with the quantitative study of low temperature (complexes (PtXMe_3 (MeS)_2CHCH(SMe) _2) (X = Cl, Br, I). These complexes were studied by dynamic nuclear magnetic resonance and the information regarding the rates of sulphur inversion was obtained by complete band-shape analysis. Chapter Five is concerned with high temperature (>333 K) fluxionality, of the previous complexes, as studied by a combination of one- and two -dimensional NMR techniques. Aside from obtaining thermodynamic parameters for all the processes, a new novel mechanism is proposed. Chapter Six is primarily concerned with the NMR investigation of the new dinuclear complexes ((PtXMe _3)_2(MeS) _2CHCH(SMe)_2) (X = Cl, Br, I). The solution properties have been established and thermo-dynamic parameters obtained for low and high temperature

  2. Patterns of risk of cancer in patients with metal-on-metal hip replacements versus other bearing surface types: a record linkage study between a prospective joint registry and general practice electronic health records in England.

    Directory of Open Access Journals (Sweden)

    Arief Lalmohamed

    Full Text Available BACKGROUND: There are concerns that metal-on-metal hip implants may cause cancer. The objective of this study was to evaluate patterns and timing of risk of cancer in patients with metal-on-metal total hip replacements (THR. METHODS: In a linkage study between the English National Joint Registry (NJR and the Clinical Practice Research Datalink (CPRD, we selected all THR surgeries (NJR between 2003 and 2010 (n = 11,540. THR patients were stratified by type of bearing surface. Patients were followed up for cancer and Poisson regression was used to derive adjusted relative rates (RR. RESULTS: The risk of cancer was similar in patients with hip resurfacing (RR 0.69; 95% Confidence Interval [CI] 0.39-1.22 or other types of bearing surfaces (RR 0.96; 95% CI 0.64-1.43 compared to individuals with stemmed metal-on-metal THR. The pattern of cancer risk over time did not support a detrimental effect of metal hip implants. There was substantial confounding: patients with metal-on-metal THRs used fewer drugs and had less comorbidity. CONCLUSIONS: Metal-on-metal THRs were not associated with an increased risk of cancer. There were substantial baseline differences between the different hip implants, indicating possibility of confounding in the comparisons between different types of THR implants.

  3. Nanoparticles of novel organotin(IV complexes bearing phosphoric triamide ligands

    Directory of Open Access Journals (Sweden)

    Zahra Shariatinia

    2013-02-01

    Full Text Available Four novel organotin(IV complexes containing phosphoric triamide ligands were synthesized and characterized by multinuclear (1H, 31P, 13C NMR, infrared, ultraviolet and fluorescence spectroscopy as well as elemental analysis. The 1H NMR spectra of complexes 1–4 proved that the Sn atoms adopt octahedral configurations. The nanoparticles of the complexes were also prepared by ultrasonication, and their SEM micrographs indicated identical spherical morphologies with particles sizes about 20–25 nm. The fluorescence spectra exhibited blue shifts for the maximum wavelength of emission upon complexation.

  4. Study on modernization processes in the coating metal surfaces (plain bearings by thermal spraying

    Directory of Open Access Journals (Sweden)

    Elena IRIMIE

    2011-09-01

    Full Text Available Knowledge accumulated within the metal coating through thermal spraying allows the understanding of aspects related to the coat structure phenomena, in this case of the routs that need to be followed in order to create strong and stabile connections between the coats subsided through thermal spraying, between the particles that compose those coats, respectively. However, all this knowledge does not ensure the understanding of some practical situations that are apparently paradoxes, as for instance the absence of tin bronze adherence to ignobly steel holders, the perfect adherence of bronze to the aluminum on the same types of holders, in the context in which both elements, tin and aluminum, respectively are found in equal quantity in the two type of bonze that maintain them in solid solutions (below 10%.The parallel study in the sinter antifriction domain has offered information regarding the optimal correlation between the composition of antifriction material and the required type of application, the optimal pinches level and the way that this morphological characteristic may be influenced. By experimental research it is necessary to determine the conditions under which such coverage can be obtained by thermal spraying of the metal coatings.

  5. Oligomeric rare-earth metal cluster complexes with endohedral transition metal atoms

    Energy Technology Data Exchange (ETDEWEB)

    Steinberg, Simon; Zimmermann, Sina; Brühmann, Matthias; Meyer, Eva; Rustige, Christian; Wolberg, Marike; Daub, Kathrin; Bell, Thomas; Meyer, Gerd, E-mail: gerd.meyer@uni-koeln.de

    2014-11-15

    Comproportionation reactions of rare-earth metal trihalides (RX{sub 3}) with the respective rare-earth metals (R) and transition metals (T) led to the formation of 22 oligomeric R cluster halides encapsulating T, in 19 cases for the first time. The structures of these compounds were determined by single-crystal X-ray diffraction and are composed of trimers ((T{sub 3}R{sub 11})X{sub 15}-type, P6{sub 3}/m), tetramers ((T{sub 4}R{sub 16})X{sub 28}(R{sub 4}) (P-43m), (T{sub 4}R{sub 16})X{sub 20} (P4{sub 2}/nnm), (T{sub 4}R{sub 16})X{sub 24}(RX{sub 3}){sub 4} (I4{sub 1}/a) and (T{sub 4}R{sub 16})X{sub 23} (C2/m) types of structure) and pentamers ((Ru{sub 5}La{sub 14}){sub 2}Br{sub 39}, Cc) of (TR{sub r}){sub n} (n=2–5) clusters. These oligomers are further enveloped by inner (X{sup i}) as well as outer (X{sup a}) halido ligands, which possess diverse functionalities and interconnect like oligomers through i–i, i–a and/or a–i bridges. The general features of the crystal structures for these new compounds are discussed and compared to literature entries as well as different structure types with oligomeric T centered R clusters. Dimers and tetramers originating from the aggregation of (TR{sub 6}) octahedra via common edges are more frequent than trimers and pentamers, in which the (TR{sub r}) clusters share common faces. - Graphical abstract: Rare earth-metal cluster complexes with endohedral transition metal atoms (TR{sub 6}) may connect via common edges or faces to form dimers, trimers, tetramers and pentamers of which the tetramers are the most prolific. Packing effects and electron counts play an important role. - Highlights: • Rare-earth metal cluster complexes encapsulate transition metal atoms. • Oligomers are built via connection of octahedral clusters via common edges or faces. • Dimers through pentamers with closed structures are known. • Tetramers including a tetrahedron of endohedral atoms are the most prolific.

  6. Stable Te isotope fractionation in tellurium-bearing minerals from precious metal hydrothermal ore deposits

    Science.gov (United States)

    Fornadel, Andrew P.; Spry, Paul G.; Haghnegahdar, Mojhgan A.; Schauble, Edwin A.; Jackson, Simon E.; Mills, Stuart J.

    2017-04-01

    The tellurium isotope compositions of naturally-occurring tellurides, native tellurium, and tellurites were measured by multicollector-inductively coupled plasma-mass spectrometry (MC-ICP-MS) and compared to theoretical values for equilibrium mass-dependent isotopic fractionation of representative Te-bearing species estimated with first-principles thermodynamic calculations. Calculated fractionation models suggest that 130/125Te fractionations as large as 4‰ occur at 100 °C between coexisting tellurates (Te VI) and tellurides (Te -II) or or native tellurium Te(0), and smaller, typically secondary emmonsite, δ130/125Te compositions were identical. The coincidence of δ130/125Te between all oxidized and reduced species in this study and the apparent lack of isotopic fractionation between native tellurium and emmonsite in one sample suggest that oxidation processes cause little to no fractionation. Because Te is predominantly transported as an oxidized aqueous phase or as a reduced vapor phase under hydrothermal conditions, either a reduction of oxidized Te in hydrothermal liquids or deposition of Te from a reduced vapor to a solid is necessary to form the common tellurides and native tellurium in ore-forming systems. Our data suggest that these sorts of reactions during mineralization may account for a ∼3‰ range of δ130/125Te values. Based on the data ranges for Te minerals from various ore deposits, the underpinning geologic processes responsible for mineralization seem to have primary control on the magnitude of fractionation, with tellurides in epithermal gold deposits showing a narrower range of isotope values than those in orogenic gold and volcanogenic massive sulfide deposits.

  7. Pt(II) diimine complexes bearing carbazolyl-capped acetylide ligands: synthesis, tunable photophysics and nonlinear absorption.

    Science.gov (United States)

    Liu, Rui; Chen, Hongbin; Chang, Jin; Li, Yuhao; Zhu, Hongjun; Sun, Wenfang

    2013-01-01

    A series of new Pt(II) diimine complexes with different carbazolyl-capped acetylide ligands (Pt-1–Pt-5) were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. All complexes exhibit ligand-centered 1π,π* transitions in the UV region, and broad, structureless metal-to-ligand charge transfer (1MLCT)/ligand-to-ligand charge transfer (1LLCT) absorption bands in the visible spectral region. All complexes are emissive in solution at room temperature, with the emitting state being tentatively assigned to the 3MLCT/3LLCT states for Pt-1–Pt-4, and the emitting state of Pt-5 exhibiting a switch from the 3π,π* state in high-polarity solvents to the 3MLCT state in low-polarity solvents. Complexes Pt-1–Pt-5 all exhibit moderate triplet transient absorption (TA) from the visible to the NIR region, where reverse saturable absorption (RSA) could occur. The spectroscopic studies and theoretical calculations indicate that the photophysical properties of these Pt complexes can be tuned drastically by the carbazolyl-capped acetylide ligand, which would be useful for rational design of transition-metal complexes with high emission quantum yield, long excited-state lifetime, broadband excited-state absorption, and strong nonlinear transmittance for organic light-emitting and/or broadband nonlinear transmission applications.

  8. Hydrogen storage and evolution catalysed by metal hydride complexes.

    Science.gov (United States)

    Fukuzumi, Shunichi; Suenobu, Tomoyoshi

    2013-01-07

    The storage and evolution of hydrogen are catalysed by appropriate metal hydride complexes. Hydrogenation of carbon dioxide by hydrogen is catalysed by a [C,N] cyclometalated organoiridium complex, [Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))benzoic acid-κC(3))(OH(2))](2)SO(4) [Ir-OH(2)](2)SO(4), under atmospheric pressure of H(2) and CO(2) in weakly basic water (pH 7.5) at room temperature. The reverse reaction, i.e., hydrogen evolution from formate, is also catalysed by [Ir-OH(2)](+) in acidic water (pH 2.8) at room temperature. Thus, interconversion between hydrogen and formic acid in water at ambient temperature and pressure has been achieved by using [Ir-OH(2)](+) as an efficient catalyst in both directions depending on pH. The Ir complex [Ir-OH(2)](+) also catalyses regioselective hydrogenation of the oxidised form of β-nicotinamide adenine dinucleotide (NAD(+)) to produce the 1,4-reduced form (NADH) under atmospheric pressure of H(2) at room temperature in weakly basic water. In weakly acidic water, the complex [Ir-OH(2)](+) also catalyses the reverse reaction, i.e., hydrogen evolution from NADH to produce NAD(+) at room temperature. Thus, interconversion between NADH (and H(+)) and NAD(+) (and H(2)) has also been achieved by using [Ir-OH(2)](+) as an efficient catalyst and by changing pH. The iridium hydride complex formed by the reduction of [Ir-OH(2)](+) by H(2) and NADH is responsible for the hydrogen evolution. Photoirradiation (λ > 330 nm) of an aqueous solution of the Ir-hydride complex produced by the reduction of [Ir-OH(2)](+) with alcohols resulted in the quantitative conversion to a unique [C,C] cyclometalated Ir-hydride complex, which can catalyse hydrogen evolution from alcohols in a basic aqueous solution (pH 11.9). The catalytic mechanisms of the hydrogen storage and evolution are discussed by focusing on the reactivity of Ir-hydride complexes.

  9. Redox-inactive metal ions promoted the catalytic reactivity of non-heme manganese complexes towards oxygen atom transfer.

    Science.gov (United States)

    Choe, Cholho; Yang, Ling; Lv, Zhanao; Mo, Wanling; Chen, Zhuqi; Li, Guangxin; Yin, Guochuan

    2015-05-21

    Redox-inactive metal ions can modulate the reactivity of redox-active metal ions in a variety of biological and chemical oxidations. Many synthetic models have been developed to help address the elusive roles of these redox-inactive metal ions. Using a non-heme manganese(II) complex as the model, the influence of redox-inactive metal ions as a Lewis acid on its catalytic efficiency in oxygen atom transfer was investigated. In the absence of redox-inactive metal ions, the manganese(II) catalyst is very sluggish, for example, in cyclooctene epoxidation, providing only 9.9% conversion with 4.1% yield of epoxide. However, addition of 2 equiv. of Al(3+) to the manganese(II) catalyst sharply improves the epoxidation, providing up to 97.8% conversion with 91.4% yield of epoxide. EPR studies of the manganese(II) catalyst in the presence of an oxidant reveal a 16-line hyperfine structure centered at g = 2.0, clearly indicating the formation of a mixed valent di-μ-oxo-bridged diamond core, Mn(III)-(μ-O)2-Mn(IV). The presence of a Lewis acid like Al(3+) causes the dissociation of this diamond Mn(III)-(μ-O)2-Mn(IV) core to form monomeric manganese(iv) species which is responsible for improved epoxidation efficiency. This promotional effect has also been observed in other manganese complexes bearing various non-heme ligands. The findings presented here have provided a promising strategy to explore the catalytic reactivity of some di-μ-oxo-bridged complexes by adding non-redox metal ions to in situ dissociate those dimeric cores and may also provide clues to understand the mechanism of methane monooxygenase which has a similar diiron diamond core as the intermediate.

  10. Dihydrogen bonding vs metal-σ interaction in complexes between H2 and metal hydride.

    Science.gov (United States)

    Alkorta, Ibon; Elguero, Jose; Solimannejad, Mohammad; Grabowski, Sławomir J

    2011-01-20

    The complexes formed by hydrogen with metal hydrides (LiH, NaH, BeH(2), MgH(2), BH(3), AlH(3), Li(2)H(2), Na(2)H(2), Be(2)H(4), and Mg(2)H(4)) have been theoretically studied at the MP2/aug-cc-pVTZ, MP2/aug-cc-pVQZ and CCSD(T)/aug-cc-pVTZ//CCSD/aug-cc-pVTZ levels of theory. The hydrogen molecule can act as a Lewis acid or base. In the first case, a dihydrogen bonded complex is obtained and in the second an interaction between the σ-bond of the hydrogen molecule and an empty orbital of the metal atoms is found. Quantum theory of atoms in molecules and natural bond orbitals methods have been applied to analyze the intermolecular interactions. Additionally, the cooperativity effects are analyzed for selected complexes with two H(2) molecules where both kinds of interactions exist simultaneously.

  11. Metamorphic Evolution of Garnet-bearing Epidote-Barroisite Schist from the Meratus Complex in South Kalimantan, Indonesia

    Directory of Open Access Journals (Sweden)

    Nugroho Imam Setiawan

    2015-09-01

    Full Text Available DOI:10.17014/ijog.2.3.139-156This paper presents metamorphic evolution of metamorphic rocks from the Meratus Complex in South Kalimantan, Indonesia. Eight varieties of metamorphic rocks samples from this location, which are garnet-bearing epidote-barroisite schist, epidote-barroisite schist, glaucophane-quartz schist, garnet-muscovite schist, actinolite-talc schist, epidote schist, muscovite schist, and serpentinite, were investigated in detail its petrological and mineralogical characteristics by using polarization microscope and electron probe micro analyzer (EPMA. Furthermore, the pressure-temperature path of garnet-bearing epidote-barroisite schist was estimated by using mineral parageneses, reaction textures, and mineral chemistries to assess the metamorphic history. The primary stage of this rock might be represented by the assemblage of glaucophane + epidote + titanite ± paragonite. The assemblage yields 1.7 - 1.0 GPa in assumed temperature of 300 - 550 °C, which is interpreted as maximum pressure limit of prograde stage. The peak P-T condition estimated on the basis of the equilibrium of garnet rim, barroisite, phengite, epidote, and quartz, yields 547 - 690 °C and 1.1 - 1.5 GPa on the albite epidote amphibolite-facies that correspond to the depth of 38 - 50 km. The retrograde stage was presented by changing mineral compositions of amphiboles from the Si-rich barroisite to the actinolite, which lies near 0.5 GPa at 350 °C. It could be concluded that metamorphic rocks from the Meratus Complex experienced low-temperature and high-pressure conditions (blueschist-facies prior to the peak metamorphism of the epidote amphibolite-facies. The subduction environments in Meratus Complex during Cretaceous should be responsible for this metamorphic condition.

  12. Metamorphic Evolution of Garnet-bearing Epidote-Barroisite Schist from the Meratus Complex in South Kalimantan, Indonesia

    Directory of Open Access Journals (Sweden)

    Nugroho Imam Setiawan

    2015-10-01

    Full Text Available This paper presents metamorphic evolution of metamorphic rocks from the Meratus Complex in South Kalimantan, Indonesia. Eight varieties of metamorphic rocks samples from this location, which are garnet-bearing epidote-barroisite schist, epidote-barroisite schist, glaucophane-quartz schist, garnet-muscovite schist, actinolite-talc schist, epidote schist, muscovite schist, and serpentinite, were investigated in detail its petrological and mineralogical characteristics by using polarization microscope and electron probe micro analyzer (EPMA. Furthermore, the pressure-temperature path of garnet-bearing epidote-barroisite schist was estimated by using mineral parageneses, reaction textures, and mineral chemistries to assess the metamorphic history. The primary stage of this rock might be represented by the assemblage of glaucophane + epidote + titanite ± paragonite. The assemblage yields 1.7 - 1.0 GPa in assumed temperature of 300 - 550 °C, which is interpreted as maximum pressure limit of prograde stage. The peak P-T condition estimated on the basis of the equilibrium of garnet rim, barroisite, phengite, epidote, and quartz, yields 547 - 690 °C and 1.1 - 1.5 GPa on the albite epidote amphibolite-facies that correspond to the depth of 38 - 50 km. The retrograde stage was presented by changing mineral compositions of amphiboles from the Si-rich barroisite to the actinolite, which lies near 0.5 GPa at 350 °C. It could be concluded that metamorphic rocks from the Meratus Complex experienced low-temperature and high-pressure conditions (blueschist-facies prior to the peak metamorphism of the epidote amphibolite-facies. The subduction environments in Meratus Complex during Cretaceous should be responsible for this metamorphic condition.

  13. Structural and thermal characterization of ternary complexes of piroxicam and alanine with transition metals: Uranyl binary and ternary complexes of piroxicam. Spectroscopic characterization and properties of metal complexes

    Science.gov (United States)

    Mohamed, Gehad G.

    2005-12-01

    Ternary Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and UO 2(II) complexes with piroxicam (Pir) drug (H 2L 1) and dl-alanine (Ala) (HL 2) and also the binary UO 2(II) complex with Pir were studied. The structures of the complexes were elucidated using elemental, IR, molar conductance, magnetic moment, diffused reflectance and thermal analyses. The UO 2(II) binary complex was isolated in 1:2 ratio with the formula [UO 2(H 2L) 2](NO 3) 2. The ternary complexes were isolated in 1:1:1 (M:H 2L 1:L 2) ratios. The solid complexes were isolated in the general formulae [M(H 2L)(L 2)(Cl) n(H 2O) m]· yH 2O (M = Fe(III) ( n = 2, m = 0, y = 1), Co(II) ( n = 1, m = 1, y = 2) and Ni(II) ( n = 1, m = 1, y = 0)); [M(H 2L)(L 2)](X) z· yH 2O (M = Cu(II) (X = AcO, z = 1, y = 0), Zn(II) (X = AcO, z = 1, y = 3) and UO 2(II) (X = NO 3, z = 1, y = 2)). Pir behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl-O groups, while Ala behaves as a uninegatively bidentate ligand coordinated to the metal ions via the deprotonated carboxylate-O and amino-N. The magnetic and reflectance spectral data show that the complexes have octahedral geometry except Cu(II) and Zn(II) complexes have tetrahedral structures. The thermal decomposition of the complexes was discussed in relation to structure, and the thermodynamic parameters of the decomposition stages were evaluated.

  14. Approaching the Hartree-Fock limit for organotransition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, III, Henry F. [Univ. of Texas, Austin, TX (United States). Dept. of Chemistry. Inst. for Theoretical Chemistry; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry. Lawrence Berkeley Lab.

    1981-04-01

    In theoretical studies of the electronic structure of organometallic complexes, the choice of basis set is critical, much more so than for analogous studies of molecules containing only H, C, N, and O. In this paper, this problem is discussed in the light of structural predictions for the transition metal hydrides MH, MH2, and MH4, for the fluorides MF2 and MF3, and for Ni(CO)4, Ni(C2H4)3, (CO)3NiCH2, and Ni(C4H4)2.

  15. Copper dynamics in doped metal-bis(histidine) complexes.

    Science.gov (United States)

    Colaneri, Michael J; Vitali, Jacqueline

    2014-07-03

    Electron paramagnetic resonance (EPR) temperature-dependent measurements were undertaken on three Cu(II)-doped metal-histidine complexes to assess copper site dynamic behavior. Previous single-crystal EPR analysis on two of these, zinc d,l-histidine pentahydrate (ZnDLH) and bis(l-histidinato)cadmium dihydrate (CdLH), found that doped Cu(2+) can be modeled as hopping between two neighboring conformational states, with a temperature-dependent rate becoming large enough at room temperature to produce an "averaged" spectrum. By comparing spectra from their powdered form, we show that Cu(2+) doped into a third system, Cd(2+)-d,l-histidine (CdDLH), also exhibits temperature-dependent EPR with features indicating a similar motional-averaging process. In addition, the change of g and copper hyperfine parameters from low to high temperature for CdDLH resembles that in ZnDLH, whereas the change in these parameters for CdLH is like that found in a fourth copper-doped system, zinc l-histidine dihydrate (ZnLH). Taken together, these results suggest that averaging motion between neighboring copper sites is common in metal-bis(histidine) compounds. More detailed studies on biological models are thus warranted, especially because they reveal unique relationships between structure, dynamic processes, and stability and can lead to a better understanding of the role played by site flexibility in copper proteins.

  16. Stability of complex coacervate core micelles containing metal coordination polymer.

    Science.gov (United States)

    Yan, Yun; de Keizer, Arie; Cohen Stuart, Martien A; Drechsler, Markus; Besseling, Nicolaas A M

    2008-09-01

    We report on the stability of complex coacervate core micelles, i.e., C3Ms (or PIC, BIC micelles), containing metal coordination polymers. In aqueous solutions these micelles are formed between charged-neutral diblock copolymers and oppositely charged coordination polymers formed from metal ions and bisligand molecules. The influence of added salt, polymer concentration, and charge composition was investigated by using light scattering and cryo-TEM techniques. The scattering intensity decreases strongly with increasing salt concentration until a critical salt concentration beyond which no micelles exist. The critical micelle concentration increases almost exponentially with the salt concentration. From the scattering results it follows that the aggregation number decreases with the square root of the salt concentration, but the hydrodynamic radius remains constant or increases slightly. It was concluded that the density of the core decreases with increasing ionic strength. This is in agreement with theoretical predictions and is also confirmed by cryo-TEM measurements. A complete composition diagram was constructed based on the composition boundaries obtained from light scattering titrations.

  17. Modeling platinum group metal complexes in aqueous solution.

    Science.gov (United States)

    Lienke, A; Klatt, G; Robinson, D J; Koch, K R; Naidoo, K J

    2001-05-07

    We construct force fields suited for the study of three platinum group metals (PGM) as chloranions in aqueous solution from quantum chemical computations and report experimental data. Density functional theory (DFT) using the local density approximation (LDA), as well as extended basis sets that incorporate relativistic corrections for the transition metal atoms, has been used to obtain equilibrium geometries, harmonic vibrational frequencies, and atomic charges for the complexes. We found that DFT calculations of [PtCl(6)](2-).3H(2)O, [PdCl(4)](2-).2H(2)O, and [RhCl(6)](3-).3H(2)O water clusters compared well with molecular mechanics (MM) calculations using the specific force field developed here. The force field performed equally well in condensed phase simulations. A 500 ps molecular dynamics (MD) simulation of [PtCl(6)](2-) in water was used to study the structure of the solvation shell around the anion. The resulting data were compared to an experimental radial distribution function derived from X-ray diffraction experiments. We found the calculated pair correlation functions (PCF) for hexachloroplatinate to be in good agreement with experiment and were able to use the simulation results to identify and resolve two water-anion peaks in the experimental spectrum.

  18. Reactions of benzaldehyde with trialkylsilyl metal carbonyl complexes

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.L.; Gladysz, J.A.

    1979-10-10

    The use of trialkylsilyl metal carbonyl complexes as reagents for organometallic synthesis was investigated. In this communication it was reported that the metal silanes (CO)/sub 5/MnSi(CH/sub 3/)/sub 3/(1), (CO)/sub 4/Fe(SiCH/sub 3/)/sub 3/)/sub 2/(2), and (CO/sub 4/)FeSi(CH/sub 3/)/sub 2/(CH/sub 2/CH/sub 2/Si(CH/sub 3/)/sub 2/(3) undergo reactions with benzaldehyde which result, under appropriate conditions, in the formation of ..cap alpha..-silyloxybenzyl- and benzylidene-derived ligands. It was reported that a strongly oxygenophilic group must be present on manganese in order for a benzaldehyde adduct to be detectably formed. The catalytic hydrosilyation of aldehydes and ketones has been postulated to involve a similar carbonyl group addition by a catalytically active L/sb n/M(H)SiR/sub 3/ species. The presence of chelating disilane ligand enables the chemistry of 3 to dramaticaly diverge from that of 2. With aliphatic aldehydes and ketones, 1 and 2 react differently. (DP)

  19. Complexation by natural heterogeneous compounds: Site occupation distribution functions, a normalized description of metal complexation

    Science.gov (United States)

    Buffle, J.; Altmann, R. S.; Filella, M.; Tessier, A.

    1990-06-01

    This paper presents a new conceptual approach to interpreting titration curves of metal complexation by physically and chemically heterogeneous natural complexants such as humic acids, clays, complete soils, or sediments. The physico-chemical and analytical difficulties encountered with such systems are reviewed by comparison with a system containing only a few simple ligands, followed by discussion of the new approach on the same basis. It is shown that interpretation of heterogeneous complexant properties necessitates a preliminary transformation of experimental raw data into a function sufficiently normalized so as to allow comparison of results obtained under different conditions. A normalized function called a Site Occupation Distribution Function (SODF) and its potential usefulness is described here. The SODF is a readily computable function which relates the complexation buffer intensity of the system to the differential free energy of the complexation sites present. Its major interest is that it enables one to obtain both a rigorous mathematical description of the complexant properties (even when highly heterogeneous) at the macroscopic level and, in certain cases, an estimation of the molecular-scale behavior of particular site types. The relationship of the SODF to other distribution functions proposed in the literature is discussed and applications are exemplified using simulated and real natural systems. In particular, its utility is discussed in detail for (1) discriminating between different site types (major, minor, dominant, background), (2) evaluating the degree of heterogeneity of an unknown complexant system, (3) estimating the nature and true thermodynamic constants of complexes, and (4) yielding a rigorous definition of "complexation capacity."

  20. Synthesis, physico-chemical and antimicrobial screening studies on 14 and 16-membered hexaazamacrocyclic complexes bearing pendant amine groups

    Directory of Open Access Journals (Sweden)

    Shakir Mohammad

    2006-01-01

    Full Text Available The synthesis and characterization of a series of 14 and 16-membered hexaazamacrocyclic complexes, which were obtained via template condensation of 1,2- diaminoethane or 1,3-diaminopropane, formaldehyde and hydrazine hydrate in the presence of first row transition metal salts are reported. Complexes of the types, [ML¹(NO32]; [CuL¹](NO32 and [ML²Cl2]; [CuL²]Cl2 (where M = Co(II, Ni(II and Zn(II, were obtained. Elemental analyses, IR spectra, ¹H NMR, EPR, UV-Vis, magnetic susceptibility and conductivity measurements have ascertained the overall geometry and stereochemistry of the complexes. An octahedral geometry has been suggested for all the complexes, except for copper compounds, in which the metal centre coordinates to the four nitrogen atoms of macrocyclic ligand in a square planar fashion. These complexes were screened against different fungi and bacteria in vitro and were found to be potentially active in the concentration 5 mg mL-1.

  1. The Effect of Complex Formation upon the Redox Potentials of Metallic Ions. Cyclic Voltammetry Experiments.

    Science.gov (United States)

    Ibanez, Jorge G.; And Others

    1988-01-01

    Describes experiments in which students prepare in situ soluble complexes of metal ions with different ligands and observe and estimate the change in formal potential that the ion undergoes upon complexation. Discusses student formation and analysis of soluble complexes of two different metal ions with the same ligand. (CW)

  2. The Effect of Complex Formation upon the Redox Potentials of Metallic Ions. Cyclic Voltammetry Experiments.

    Science.gov (United States)

    Ibanez, Jorge G.; And Others

    1988-01-01

    Describes experiments in which students prepare in situ soluble complexes of metal ions with different ligands and observe and estimate the change in formal potential that the ion undergoes upon complexation. Discusses student formation and analysis of soluble complexes of two different metal ions with the same ligand. (CW)

  3. Metal-bearing fine particle sources in a coastal industrialized environment

    Science.gov (United States)

    Mbengue, Saliou; Alleman, Laurent Y.; Flament, Pascal

    2017-01-01

    Fine (primary or secondary submicron particles and mechanical procedures in open air, or local traffic, which lead to the emission of coarser particles (> 1 μm). The trace elements As, Cd, Ni, Pb, Sb, V and Zn, characteristics of the local industrial activities display 60% to 85% of their mass in the submicron and ultrafine fractions and appear highly enriched, by reference to the crustal source. High atmospheric pressure periods, corresponding to northeasterly winds, induce the highest contributions of metalworking emissions and the highest PM2.5 concentrations (32.5 ± 11.9 μg·m- 3). A Principal Component Analysis of the dataset produces 7 factors associated to metallurgy-, steelworks-, oil processing-, coal combustion-, neighboring traffic-, dust resuspension- and sea salt-sources, that explain the obtained concentrations. A Multiple Linear Regression Analysis confirms that Fe-Mn alloy refining, iron- and steel-making are the main sources (> 40%) controlling metal concentrations in PM2.5. Less predictably, resuspended dust and fresh/aged sea salts are also significant contributors (≈ 20%). Considering the related health hazards, authorities should pay more attention to the exposure of people living in this area and the possible impact of fine particles in terms of public health.

  4. Stacking interaction in metal complexes with compositions of DNA and heteroaromatic N-bases

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The current development in the intramolecular aromatic-ring stacking i nteractions in the complexes with compositions of DNA and heteroaromatic N-bases has been reviewed to a great extent, especially the significant contributions i n several important systems about ternary mixed-ligand complexes, including nucl eotide-metal ion-po- lyaromatic amine, amino acid-metal ion-polyaromatic amine, nucleotide-metal ion-pyridine-like aromatic amine, nucleotide-metal ion-amino ac id, nucleotide-metal ion-nucleic acid base, nucleic acid base-metal ion, and the important factors affecting the intramolecular aromatic-ring stacking interacti ons in the complexes. Based on the study of stacking interaction in the complexe s, the mechanism of interaction between DNA molecules and complexes of heteroaro matic N-bases has been established, which is crucial for the design and synthesi s of the complexes acting as molecular devices of DNA.

  5. Phosphorescent emissions of phosphine copper(I) complexes bearing 8-hydroxyquinoline carboxylic acid analogue ligands

    Energy Technology Data Exchange (ETDEWEB)

    Małecki, Jan G., E-mail: gmalecki@us.edu.pl [Department of Crystallography, Institute of Chemistry, University of Silesia, Szkolna 9 street, 40-006 Katowice (Poland); Łakomska, Iwona, E-mail: iwolak@chem.umk.pl [Department of Chemistry, Nicolaus Copernicus University, Toruń (Poland); Maroń, Anna [Department of Crystallography, Institute of Chemistry, University of Silesia, Szkolna 9 street, 40-006 Katowice (Poland); Szala, Marcin [Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice (Poland); Fandzloch, Marzena [Department of Chemistry, Nicolaus Copernicus University, Toruń (Poland); Nycz, Jacek E., E-mail: jacek.nycz@us.edu.pl [Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice (Poland)

    2015-05-15

    The pseudotetrahedral complexes of [Cu(PPh{sub 3}){sub 2}(L)], where L=8-hydroxy-2-methylquinoline-7-carboxylic acid (1), 8-hydroxy-2,5-dimethylquinoline-7-carboxylic acid (2) or 5-chloro-8-hydroxy-2-methylquinoline-7-carboxylic acid (3) have been synthesized and structurally characterized by X-ray crystallography. Their properties have been examined through combinations of IR, NMR, electronic absorption spectroscopy and cyclic voltammetry. The complexes exhibit extraordinary photophysical properties. Complex (1) in solid state exhibits an emission quantum yield of 4.67% and an excited life time of 1.88 ms (frozen DCM solution up to 6.7 ms). When dissolved in a coordinating solvent (acetonitrile) the charge transfer emission was quenched on a microsecond scale. - Highlights: • Synthesis of copper(I) complexes with 8-hydroxyquinoline carboxylic acid ligands. • Very long lived phosphorescent copper(I) complexes. • [Cu(PPh{sub 3}){sub 2}(L)] where L=8-hydroxy-2-methylquinoline-7-carboxylic acid luminesce in the solid state exhibits extremely long lifetime on millisecond scale (1.9 ms). • In frozen MeOH:EtOH solution lifetime increases to 7 ms. • Quantum efficiency equal to 4.7%.

  6. Co-transport of metal complexes by the green mussel Perna viridis.

    Science.gov (United States)

    Chuang, Chia-Ying; Wang, Wen-Xiong

    2006-07-15

    We examined the uptake of ligand-bound metals (Cd and Zn) by the green mussel Perna viridis using defined artificial seawater. Different free ion concentrations (1 pM to 10 microM) in uptake solutions were created by adding different amounts of total metals (Cd 0.1 nM to 0.1 mM; Zn 0.5 nM to 0.05 mM) and ligands (EDTA, NTA, citric acid). Our results showed that Cd and Zn uptake could not be fully explained by the free Cd and Zn concentrations in the presence of different ligands, indicating that metal-ligand complexes were at least partially available for uptake by the mussels. Total Zn concentrations appeared to be a better predictor of metal uptake than the free Zn ion concentrations in the presence of different ligands. Uptake of lipophilic organic metal complexes was substantially greater than the hydrophilic metal complexes, even though the free ion concentration was comparable or lower. Moreover, the radiolabeled ligand compounds were directly accumulated by the mussels. The accumulation of metal complexes may explain the increased metal uptake with increasing ligand and total metal concentration, even though the free ion metal concentration was constant. Overall, our experimental results indicated that free metal ion cannot fully explain metal uptake since metal complex species were also available to the mussels to some extent, apparently through a co-transport process.

  7. Metals complexation with humic acids in surface water of different natural–climatic zones

    Directory of Open Access Journals (Sweden)

    Dinu M. I.

    2013-04-01

    Full Text Available Humic acids extracted from different soils. The stability constants of metal humates and acid dissociation constant humic acids were calculated. Forms of metals in natural waters was determined with use account their chemical composition and content and properties of organic matter. We assessed metals speciation in water objects with account for competitive reactions resulting in formation of hydroxide, hydrocarbonate, sulfate, and chloride metal complexes and obtained a competitive series of metal activity in natural waters of the zones considered.

  8. Backbone tuning in indenylidene–ruthenium complexes bearing an unsaturated N-heterocyclic carbene

    Directory of Open Access Journals (Sweden)

    César A. Urbina-Blanco

    2010-11-01

    Full Text Available The steric and electronic influence of backbone substitution in IMes-based (IMes = 1,3-bis(2,4,6-trimethylphenylimidazol-2-ylidene N-heterocyclic carbenes (NHC was probed by synthesizing the [RhCl(CO2(NHC] series of complexes to quantify experimentally the Tolman electronic parameter (electronic and the percent buried volume (%Vbur, steric parameters. The corresponding ruthenium–indenylidene complexes were also synthesized and tested in benchmark metathesis transformations to establish possible correlations between reactivity and NHC electronic and steric parameters.

  9. Binding Isotherms and Cooperative Effects for Metal-DNA Complexes

    CERN Document Server

    Gelagutashvili, Eteri

    2008-01-01

    The stoichiometric binding constants of Nickel(II), Cobalt(II), Manganese(II), Silver(I), Zinc(II) ions with DNA, from Spirulina platensis were determined from their binding isotherms by equilibrium dialysis and atomic absorption spectroscopy. It was shown, that the nature of these ions interaction with DNA, from S .platensis is different. For Cobalt(II), Zinc(II) ions were observed cooperative effects and existence of two different types of the binding sites. Nickel(II)_, Silver(I) -DNA complexes shows independent and identical binding sites and Manganese(II)_ negative cooperative interaction. The logarithm of binding constants for Cobalt (II)_, Nickel (II)_, Manganese (II)_, Zinc (II)_, Silver (I) - DNA, from S. platensis in 3 mM Na(I) are 5.11; 5.18; 4.77; 5.05; 5.42; respectively. The linear correlation of logarithm of binding constants (for complexes of metal-DNA from S. platensis) and the covalent index of Pauling are observed.

  10. Porous gold nanobelts templated by metal-surfactant complex nanobelts.

    Science.gov (United States)

    Li, Lianshan; Wang, Zhijian; Huang, Teng; Xie, Jinglin; Qi, Limin

    2010-07-20

    Unique, porous gold nanobelts consisting of self-organized nanoparticles were synthesized in a high yield by morphology-preserved transformation from metal-surfactant complex precursor nanobelts formed by a bolaform surfactant dodecane-1,12-bis(trimethylammonium bromide) (N-C(12)-NBr(2)) and HAuCl(4). It was revealed that the precursor nanobelts of the stoichiometric N-C(12)-N(AuCl(4))(2) complex formed through electrostatic combination of the positively charged quaternary ammonium headgroups of N-C(n)-NBr(2) and the negatively charged AuCl(4)(-) ions. They were subsequently converted into porous gold nanobelts with shrunken sizes upon reduction by NaBH(4). The morphology of the produced gold nanostructures could be adjusted by changing the mixing ratio between N-C(12)-NBr(2) and HAuCl(4) in the reaction solution. It was found that the obtained porous Au nanobelts exhibited enhanced catalytic activity toward reduction of 4-nitrophenol compared with solid gold nanobelts, probably owing to their larger surface area and more active sites.

  11. Hemocompatibility Improvement of Chromium-Bearing Bare-Metal Stent Platform After Magnetoelectropolishing

    Science.gov (United States)

    Rokicki, Ryszard; Haider, Waseem; Maffi, Shivani Kaushal

    2015-01-01

    Research was undertaken to determine the influence of the increased content of chromium in the outermost passive layer of magneto-electrochemically refined Co-Cr alloy L-605 surface on its hemocompatibility. The chemistry, roughness, surface energy, and wettability of conventionally electropolished (EP) and magnetoelectropolished (MEP) samples were studied with x-ray photoelectron spectroscopy (XPS), open circuit potential, atomic force microscopy, and contact angle meter. In vitro hemocompatibility of tested material surfaces was assessed using two important indicators of vascular responses to biomaterial, namely endothelialization and platelets adhesion. The endothelialization was assessed by seeding and incubating samples with human umbilical vein endothelial cells (HUVEC) for 3 days before counting and observing them under a fluorescent microscope. The platelet (rich plasma blood) adhesion and activation test on EP and MEP L-605 alloy surfaces was assessed using a laser scanning confocal microscope. The XPS analysis of MEP samples showed significant enrichment of the passive layer with Cr and O when compared with the EP one. The amount of other elements in the passive layer did not show a significant difference between EP and MEP treatments. The adhesion of HUVEC cells shows remarkable affinity to surfaces enriched in Cr (MEP) with almost 100% confluency. In addition, the number of platelets that adhered to standard EP surfaces was higher compared to the MEP surface. The present study shows that the chromium-enriched surface of cobalt-chromium alloy L-605 by the magnetoelectropolishing process tremendously improves surface hemocompatibility with regard to stent functionality by enhanced endothelialization and lower platelet adhesion and should be taken under consideration as an alternative surface of biodegradable polymer drug-eluting stents, polymer-free drug-eluting stents as well as bare-metal stents.

  12. Water-in-Supercritical CO2 Microemulsion Stabilized by a Metal Complex.

    Science.gov (United States)

    Luo, Tian; Zhang, Jianling; Tan, Xiuniang; Liu, Chengcheng; Wu, Tianbin; Li, Wei; Sang, Xinxin; Han, Buxing; Li, Zhihong; Mo, Guang; Xing, Xueqing; Wu, Zhonghua

    2016-10-17

    Herein we propose for the first time the utilization of a metal complex for forming water-in-supercritical CO2 (scCO2 ) microemulsions. The water solubility in the metal-complex-stabilized microemulsion is significantly improved compared with the conventional water-in-scCO2 microemulsions stabilized by hydrocarbons. Such a microemulsion provides a promising route for the in situ CO2 reduction catalyzed by a metal complex at the water/scCO2 interface.

  13. Contrasting anticancer activity of half-sandwich iridium(III) complexes bearing functionally diverse 2-phenylpyridine ligands

    OpenAIRE

    Millett, Adam J.; Habtemariam, Abraha; Romero-Canelón, Isolda; Clarkson, Guy J.; Sadler, P. J.

    2015-01-01

    We report the synthesis, characterization, and antiproliferative activity of 15 iridium(III) half-sandwich complexes of the type [(η5-Cp*)Ir(2-(R′-phenyl)-R-pyridine)Cl] bearing either an electron-donating (−OH, −CH2OH, −CH3) or electron-withdrawing (−F, −CHO, −NO2) group at various positions on the 2-phenylpyridine (2-PhPy) chelating ligand giving rise to six sets of structural isomers. The X-ray crystal structures of [(η5-Cp*)Ir(2-(2′-fluorophenyl)pyridine)Cl] (1) and [(η5-Cp*)Ir(2-(4′-fluo...

  14. Extending FEAST-METAL for analysis of low content minor actinide bearing and zirconium rich metallic fuels for sodium fast reactors

    Science.gov (United States)

    Karahan, Aydın

    2011-07-01

    Computational models in FEAST-METAL fuel behaviour code have been upgraded to simulate minor actinide bearing zirconium rich metallic fuels for use in sodium fast reactors. Increasing the zirconium content to 20-40 wt.% causes significant changes in fuel slug microstructure affecting thermal, mechanical, chemical, and fission gas behaviour. Inclusion of zirconium rich phase reduces the fission gas swelling rate significantly in early irradiation. Above the threshold fission gas swelling, formation of micro-cracks, and open pores increase material compliancy enhance diffusivity, leading to rapid fuel gas swelling, interconnected porosity development and release of the fission gases and helium. Production and release of helium was modelled empirically as a function of americium content and fission gas production, consistent with previous Idaho National Laboratory studies. Predicted fuel constituent redistribution is much smaller compared to typical U-Pu-10Zr fuel operated at EBR-II. Material properties such as fuel thermal conductivity, modulus of elasticity, and thermal expansion coefficient have been approximated using the available database. Creep rate and fission gas diffusivity of high zirconium fuel is lowered by an order of magnitude with respect to the reference low zirconium fuel based on limited database and in order to match experimental observations. The new code is benchmarked against the AFC-1F fuel assembly post irradiation examination results. Satisfactory match was obtained for fission gas release and swelling behaviour. Finally, the study considers a comparison of fuel behaviour between high zirconium content minor actinide bearing fuel and typical U-15Pu-6Zr fuel pins with 75% smear density. The new fuel has much higher fissile content, allowing for operating at lower neutron flux level compared to fuel with lower fissile density. This feature allows the designer to reach a much higher burnup before reaching the cladding dose limit. On the other

  15. Direct synthesis of metal complexes starting from zero-valent metals

    Energy Technology Data Exchange (ETDEWEB)

    Gojon-Zorrilla, Gabriel; Kharisov, Boris I. [Universidad Autonoma de Nuevo Leon, Monterrey, Nuevo Leon (Mexico); Garnovskii, Alexander D. [Institute of Physical and Organic Chemistry (Russian Federation)

    1996-06-01

    The recent (1980-1994) literature on metal-vapor synthesis of coordination and organometallic compounds is reviewed. An account is given of the high-and low-temperature reactions between free metal atoms and a large variety of substrates, mainly alkenes, alkynes, dienes, arenes, funtionalized arenes, alkyl halides {beta}-diketones and simple inorganic molecules. The main experimental methods are described, as well as the results obtained thereby. It is shown that in many instances these methods present significant advantages over conventional synthetic procedures, offering unique access to some metal complexes. [Spanish] Se reviso la literatura reciente (1980-1994) sobre la sintesis de compuestos de coordinacion y compuestos organometalicos a partir de vapores metalicos. Se examinan las reacciones de los atomos metalicos libres con una gran variedad de substratos, principalmente alquenos, alquinos, dienos, hidrocarburos aromaticos y sus derivados, haluros de alquilo y arilo, {beta}-dicetonas y moleculas inorganicas simples. Se presentan los principales metodos experimentales, asi como los resultados obtenidos; se concluye que la crisintesis presenta en muchos casos ventajas significativas sobre los procedimientos sinteticos tradicionales, constituyendo frecuentemente la unica opcion disponible.

  16. Metal-metal interaction in Fischer carbene complexes: a study of ferrocenyl and biferrocenyl tungsten alkylidene complexes.

    Science.gov (United States)

    van der Westhuizen, Belinda; Speck, J Matthäus; Korb, Marcus; Friedrich, Joachim; Bezuidenhout, Daniela I; Lang, Heinrich

    2013-12-16

    A series of ferrocenyl (Fc = ferrocenyl; fc = ferrocen-1,1'-diyl) and biferrocenyl (Bfc = 1',1″-biferrocenyl; bfc = 1',1″-biferrocen-1,1‴-diyl) mono- and biscarbene tungsten(0) complexes of the type [(CO)5W═C(OMe)R] (1, R = Fc; 3, R = Bfc) and [(CO)5W═C(OMe)-R'-(OMe)C═W(CO)5] (2, R' = fc; 4, R' = bfc) were synthesized according to the classical synthetic methodology by reacting W(CO)6 with LiR (R = Fc, fc, bfc), followed by a subsequent alkylation using methyl trifluoromethanesulfonate. Electrochemical investigations were carried out on these complexes to get a closer insight into the electronic properties of 1-4. The ferrocenyl and biferrocenyl moieties in 1-4 show reversible one-electron redox events. It was further found that the Fischer carbene unit is reducible in an electrochemical one-electron transfer process. For the tungsten carbonyl moieties, irreversible oxidation processes were found. In addition, charge transfer studies were performed on 1-4 using in situ UV-vis-NIR and infrared spectroelectrochemical techniques. During the UV-vis-NIR investigations, typical low energy transitions for the mixed-valent biferrocenyl unit were found. A further observed high energy NIR absorption is attributed to a metal-metal charge transfer transition between the tungsten carbonyl fragment and the ferrocenyl/biferrocenyl group in the corresponding oxidized states, which can be described as class II systems according to Robin and Day. This assignment was verified by infrared spectroelectrochemical studies. The electrochemical investigations are supported by density functional theory calculations. The structural properties of 1-4 in the solid state were investigated by single-crystal X-ray diffraction studies showing no substituent effects on bond lengths and angles. The biferrocenyl derivatives exhibit syn-conformation of the ferrocenyl and carbene building blocks.

  17. Aluminum Alkyl Complexes Bearing Salicylaldiminato Ligands: Versatile Initiators in the Ring-Opening Polymerization of Cyclic Esters

    Directory of Open Access Journals (Sweden)

    Tiziana Fuoco

    2017-02-01

    Full Text Available Linear aliphatic polyesters are degradable thermoplastic polymers, which can be obtained by ring-opening polymerization (ROP of cyclic esters through a coordination-insertion mechanism. Aluminum based organometallic complexes have a leading position as efficient catalysts for this polymerization process. Aluminumalkyl complexes bearing salicylaldiminato ligands, although less explored, have been shown to be efficient and versatile catalysts for the ROP of various cyclic esters. These species have the potential to function as active catalysts in the ROP because of their less coordinatively saturated nature with respect to analogous SALEN-type complexes. They have been used as efficient catalysts in the ROP of commercially available cyclic esters, such as ε-caprolactone, l-lactide, rac-lactide, and glycolide. Moreover, they resulted in efficient catalysts for the ROP of cyclic esters with large ring-size and for the ROP of functionalized lactide. Furthermore, they have been used in the co- and ter-polymerization of various cyclic esters affording well controlled polymerization and a plethora of microstructural architectures, ranging from random to block to multiblock.

  18. Phosphorescent Iridium(III) Complexes Bearing Fluorinated Aromatic Sulfonyl Group with Nearly Unity Phosphorescent Quantum Yields and Outstanding Electroluminescent Properties.

    Science.gov (United States)

    Zhao, Jiang; Yu, Yue; Yang, Xiaolong; Yan, Xiaogang; Zhang, Huiming; Xu, Xianbin; Zhou, Guijiang; Wu, Zhaoxin; Ren, Yixia; Wong, Wai-Yeung

    2015-11-11

    A series of heteroleptic functional Ir(III) complexes bearing different fluorinated aromatic sulfonyl groups has been synthesized. Their photophysical features, electrochemical behaviors, and electroluminescent (EL) properties have been characterized in detail. These complexes emit intense yellow phosphorescence with exceptionally high quantum yields (ΦP > 0.9) at room temperature, and the emission maxima of these complexes can be finely tuned depending upon the number of the fluorine substituents on the pendant phenyl ring of the sulfonyl group. Furthermore, the electrochemical properties and electron injection/transporting (EI/ET) abilities of these Ir(III) phosphors can also be effectively tuned by the fluorinated aromatic sulfonyl group to furnish some desired characters for enhancing the EL performance. Hence, the maximum luminance efficiency (ηL) of 81.2 cd A(-1), corresponding to power efficiency (ηP) of 64.5 lm W(-1) and external quantum efficiency (ηext) of 19.3%, has been achieved, indicating the great potential of these novel phosphors in the field of organic light-emitting diodes (OLEDs). Furthermore, a clear picture has been drawn for the relationship between their optoelectronic properties and chemical structures. These results should provide important information for developing highly efficient phosphors.

  19. Synthesis and Characterization of Rhenium(V) Oxo Complexes Bearing PNP-Pincer Ligands

    NARCIS (Netherlands)

    Korstanje, Ties J.; Lutz, Martin; Jastrzebski, Johann T. B. H.; Klein Gebbink, Bert

    2014-01-01

    The synthesis of a series of pyridine-based PNP-pincer rhenium-oxo complexes, with phenyl (1, 3), tertbutyl (2), or cyclohexyl (4) groups on the phosphorus atoms and either a ReO2X (1, 2) or a ReCl2O (3, 4) core is reported. The structures of these compounds were characterized using H-1, C-13, and P

  20. Synthesis and catalytic activity of metallo-organic complexes bearing 5-amino 2-ethylpyridine -2-carboximidate

    Indian Academy of Sciences (India)

    LUO MEI; XU JIA; ZHANG JING CHENG

    2016-06-01

    A series of copper, cobalt, nickel and manganese complexes were synthesized and characterized. Reaction of 5-amino-2-cyanopyridine with $ MCl_{2}$·x$H_{2}O$ (M: $Cu^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Mn^{2+})$ in anhydrous ethanol resulted in the formation of four complexes $[NH_{2}EtPyCuCl_{2}(CH_{3}OH)].H_{2}O 1$, $[(NH_{2}EtPyHCl)_{3}Co]$$(Cl)_{3}.3H_{2}O 2$, $[(NH_{2}EtPy)_{2}$ 2$(H_{2}O)Ni]$ $(Cl_{2})$ 3, and $[(NH_{2}EtPy)_{2}$ 2$(H_{2}O)$ Mn]$(Cl_{2})$ 4 $[NH_{2} EtPy=5-amino-oethylpyridine-2-carboximidate], respectively. The structures of these compounds were determined by X-raydiffraction, NMR and IR spectroscopy, and elemental analysis. Each complex was then used as a catalyst in the Henry reaction, and its catalytic activity was determined by 1H NMR. Good catalytic effects were achieved (69–87%).

  1. Confinement of a bioinspired nonheme Fe(II) complex in 2D hexagonal mesoporous silica with metal site isolation.

    Science.gov (United States)

    Jollet, Véronique; Albela, Belén; Sénéchal-David, Katell; Jégou, Pascale; Kolodziej, Emilie; Sainton, Joëlle; Bonneviot, Laurent; Banse, Frédéric

    2013-08-28

    A mixed amine pyridine polydentate Fe(II) complex was covalently tethered in hexagonal mesoporous silica of the MCM-41 type. Metal site isolation was generated using adsorbed tetramethylammonium cations acting as a patterned silanol protecting mask and trimethylsilylazane as a capping agent. Then, the amine/pyridine ligand bearing a tethering triethoxysilane group was either grafted to such a pretreated silica surface prior to or after complexation to Fe(II). These two synthetic routes, denoted as two-step and one-step, respectively, were also applied to fumed silica for comparison, except that the silanol groups were capped after tethering the metal unit. The coordination of the targeted complex was monitored using UV-visible spectrophotometry and, according to XPS, the best control was achieved inside the channels of the mesoporous silica for the two-step route. For the solid prepared according to the one-step route, tethering of the complex occurred mainly at the entrance of the channel.

  2. Axial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  3. Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures.

    Science.gov (United States)

    Bogart, Justin A; Cole, Bren E; Boreen, Michael A; Lippincott, Connor A; Manor, Brian C; Carroll, Patrick J; Schelter, Eric J

    2016-12-27

    Rare earth (RE) metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare REs. To incentivize recycling, there is a clear need for the development of simple methods for targeted separations of mixtures of RE metal salts. Metal complexes of a tripodal hydroxylaminato ligand, TriNOx(3-), featured a size-sensitive aperture formed of its three η(2)-(N,O) ligand arms. Exposure of cations in the aperture induced a self-associative equilibrium comprising RE(TriNOx)THF and [RE(TriNOx)]2 species. Differences in the equilibrium constants Kdimer for early and late metals enabled simple separations through leaching. Separations were performed on RE1/RE2 mixtures, where RE1 = La-Sm and RE2 = Gd-Lu, with emphasis on Eu/Y separations for potential applications in the recycling of phosphor waste from compact fluorescent light bulbs. Using the leaching method, separations factors approaching 2,000 were obtained for early-late RE combinations. Following solvent optimization, >95% pure samples of Eu were obtained with a 67% recovery for the technologically relevant Eu/Y separation.

  4. Immobilizing Molecular Metal Dithiolene-Diamine Complexes on 2D Metal-Organic Frameworks for Electrocatalytic H2 Production.

    Science.gov (United States)

    Dong, Renhao; Zheng, Zhikun; Tranca, Diana C; Zhang, Jian; Chandrasekhar, Naisa; Liu, Shaohua; Zhuang, Xiaodong; Seifert, Gotthard; Feng, Xinliang

    2017-02-16

    Carbon electrocatalysts consisting of metal complexes such as MNx or MSx are promising alternatives to high-cost Pt catalysts for the hydrogen evolution reaction (HER). However, the exact HER active sites remain elusive. Here, molecular metal dithiolene-diamine (MS2 N2 , M=Co and Ni), metal bis(dithiolene) (MS4 ), and metal bis(diamine) (MN4 ) complexes were selectively incorporated into carbon-rich 2D metal-organic frameworks (2D MOFs) as model carbon electrocatalysts. The 2D MOF single layers, powders, and composites with graphene were thus prepared and showed definite active sites for H2 generation. The electrocatalytic HER activity of the 2D MOF-based catalysts with different metal complexes follow the order of MS2 N2 >MN4 >MS4 . Moreover, the protonation preferentially occurred on the metal atoms, and the concomitant heterolytic elimination of H2 was favored on the M-N units in the MS2 N2 active centers. The results provide an in-depth understanding of the catalytic active sites, thus making way for the future development of metal complexes in carbon-rich electrode materials for energy generation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Synthesis, characterization and studies on antioxidant and molecular docking of metal complexes of 1-(benzo[d]thiazol-2-yl)thiourea

    Indian Academy of Sciences (India)

    Harinath Yapati; Subba Rao Devineni; Suresh Chirumamilla; Seshaiah Kalluru

    2016-01-01

    In the present study, a new thiourea derivative bearing benzothiazole ligand, 1-(benzo[d]thiazol-2-yl)thiourea (btt) and its ternary metal (Cu(II), Co(II) and Ni(II)) complexes were synthesized. The structural characterization was carried out by micro analysis, IR, 1H-NMR, EPR, UV-Visible spectral analyses, molar conductance and thermal analysis studies. Spectral studies of complexes revealed that the metal complexes have distorted octahedral geometry. Molecular modelling study was performed to evaluate the recognition of target compounds at the 3MNG binding pocket. The docking results revealed that copper complex selectively binds to the crucial amino acid residues in the active site of 3MNG. The in vitro antioxidant activity of the ligand and its metal complexes was assayed by radical scavenging activity (DPPH, H2O2 and NO) and ferric reducing antioxidant power (FRAP) methods. The ligand showed moderate antioxidant activity whereas the metal complexes exhibited better antioxidant activity than that of the ligand. The results of the four methods proved that the copper complex is the most potent antioxidant among all the tested compounds.

  6. Group 4 Metalloporphyrin diolato Complexes and Catalytic Application of Metalloporphyrins and Related Transition Metal Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Du, Guodong [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    -, bis-alkoxo, and chelating diolato complexes, depending on the identity of diols and the stoichiometry employed. It was also found that tin porphyrin complexes promoted the oxidative cleavage of vicinal diols and the oxidation of α-ketols to α-diketones with dioxygen. In extending the chemistry of metalloporphyrins and analogous complexes, a series of chiral tetraaza macrocyclic ligands and metal complexes were designed and synthesized. Examination of iron(II) complexes showed that they were efficient catalysts for the cyclopropanation of styrene by diazo reagents. Good yields and high diastereoselectivity were obtained with modest enantioselectivity. A rationalization of the stereoselectivity was presented on the basis of structural factors in a carbene intermediate.

  7. Group 4 Metalloporphyrin diolato Complexes and Catalytic Application of Metalloporphyrins and Related Transition Metal Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Guodong Du

    2004-12-19

    products, including mono-, bis-alkoxo, and chelating diolato complexes, depending on the identity of diols and the stoichiometry employed. It was also found that tin porphyrin complexes promoted the oxidative cleavage of vicinal diols and the oxidation of {alpha}-ketols to {alpha}-diketones with dioxygen. In extending the chemistry of metalloporphyrins and analogous complexes, a series of chiral tetraaza macrocyclic ligands and metal complexes were designed and synthesized. Examination of iron(II) complexes showed that they were efficient catalysts for the cyclopropanation of styrene by diazo reagents. Good yields and high diastereoselectivity were obtained with modest enantioselectivity. A rationalization of the stereoselectivity was presented on the basis of structural factors in a carbene intermediate.

  8. Thin films of metal oxides grown by chemical vapor deposition from volatile transition metal and lanthanide metal complexes

    Science.gov (United States)

    Pollard, Kimberly Dona

    1998-08-01

    This thesis describes the synthesis and characterization of novel volatile metal-organic complexes for the chemical vapor deposition (CVD) of metal oxides. Monomeric tantalum complexes, lbrack Ta(OEt)sb4(beta-diketonate)) are prepared by the acid-base reaction of lbrack Tasb2(OEt)sb{10}rbrack with a beta-diketone, (RC(O)CHsb2C(O)Rsp' for R = CHsb3, Rsp' = CFsb3; R = Rsp'=C(CHsb3)sb3; R = Csb3Fsb7,\\ Rsp'=C(CHsb3)sb3;\\ R=Rsp'=CFsb3; and R = Rsp' = CHsb3). The products are characterized spectroscopically. Thermal CVD using these complexes as precursors gave good quality Tasb2Osb5 thin films which are characterized by XPS, SEM, electrical measurements, and XRD. Factors affecting the film deposition such as the type of carrier gas and the temperature of the substrate were considered. Catalyst-enhanced CVD reactions with each of the precursors and a palladium catalyst, ((2-methylallyl)Pd(acac)), were studied as a lower temperature route to good quality Tasb2Osb5 films. The decomposition mechanism at the hot substrate surface was studied. Precursors for the formation of yttria by CVD were examined. New complexes of the form (Y(hfac)sb3(glyme)), (hfac = \\{CFsb3C(O)CHC(O)CFsb3\\}sp-,\\ glyme=CHsb3O(CHsb2CHsb2O)sb{n}CHsb3 for n = 1-4) were synthesized and characterized spectroscopically. X-ray structural determinations of three new complexes were obtained. CVD reaction conditions were determined which give YOF films and, with catalyst-enhanced CVD, reaction conditions which give selective formation of Ysb2Osb3, YOF, or YFsb3. The films were studied by XPS, SEM, and XRD. Decomposition mechanisms which lead to film formation, together with a possible route for fluorine atom transfer from the ligand to the metal resulting in fluorine incorporation, were studied by analysis of exhaust products using GC-MS. Novel precursors of the form lbrack Ce(hfac)sb3(glyme)rbrack,\\ (hfac=\\{CFsb3C(O)CHC(O)CFsb3\\}sp-,\\ glyme=CHsb3O(CHsb2CHsb2O)sb{n}CHsb3, n = 1-4) for CVD of ceria were

  9. Non-centrosymmetric behavior of a clay film ion-exchanged with chiral metal complexes.

    Science.gov (United States)

    Suzuki, Yasutaka; Matsunaga, Ryoya; Sato, Hisako; Kogure, Toshihiro; Yamagishi, Akihiko; Kawamata, Jun

    2009-12-07

    SHG measurements on a highly transparent clay film ion-exchanged with chiral metal complexes revealed that the mono-molecular layer of the chiral complexes in an interlayer space acquired a non-centrosymmetric character.

  10. Complexation humic substances of soils with metal ions as the main way migration of matals from soil to water

    Science.gov (United States)

    Dinu, Marina

    2013-04-01

    Organic matter (OM) of natural waters can bind with the ions metals (IM) entering the system, thus reducing their toxic properties. OM in water consists predominantly (up to 80%) of humic acids (HA), represented by highmolecular, dyed, polyfunctional compounds. The natural-climatic zones feature various ratios of fulvic (FA) and humic acids. An important specific feature of metals as contamination elements is the fact that when they occur in the environment, their potential toxicity and bioavailability depend significantly on their speciation. In recent years, lakes have been continuously enriched in hazardous elements such as Pb, Cd, Al, and Cr on a global (regional) basis. The most important organic ligands are humic matter (HM) washed out from soils in water and metals occur in natural waters as free ions, simple complexes with inorganic and organic ligands, and mineral and organic particles of molecules and ions sorbed on the surface. The occurrence of soluble metal forms in natural waters depends on the presence of organic and inorganic anions. However, direct determinations are rather difficult. The goal was the calculation and analysis of the forms of metals in the system catchment basin, based on the chemical composition of the water body and the structural features of soil humic substances (HS).We used the following analytical techniques - leaching of humic substances from soil and sample preparation (Orlov DS, 1985), the functional characteristics of humic substances - spectral analysis methods, the definition of conditional stability constants of complexes - electrochemical methods of analysis. Our results show thet HAs of selected soil types are different in functions, and these differences effect substantially the complexing process. When analyzing the results obtained in the course of spectrometric investigation of HMs in selected soil types, we determined the following main HA characteristics: (1) predominance of oxygen bearing groups in HM of the

  11. Genotype-phenotype correlation and functional studies in patients with cystic fibrosis bearing CFTR complex alleles.

    Science.gov (United States)

    Terlizzi, Vito; Castaldo, Giuseppe; Salvatore, Donatello; Lucarelli, Marco; Raia, Valeria; Angioni, Adriano; Carnovale, Vincenzo; Cirilli, Natalia; Casciaro, Rosaria; Colombo, Carla; Di Lullo, Antonella Miriam; Elce, Ausilia; Iacotucci, Paola; Comegna, Marika; Scorza, Manuela; Lucidi, Vincenzina; Perfetti, Anna; Cimino, Roberta; Quattrucci, Serena; Seia, Manuela; Sofia, Valentina Maria; Zarrilli, Federica; Amato, Felice

    2017-04-01

    The effect of complex alleles in cystic fibrosis (CF) is poorly defined for the lack of functional studies. To describe the genotype-phenotype correlation and the results of either in vitro and ex vivo studies performed on nasal epithelial cells (NEC) in a cohort of patients with CF carrying cystic fibrosis transmembrane conductance regulator (CFTR) complex alleles. We studied 70 homozygous, compound heterozygous or heterozygous for CFTR mutations: p.[Arg74Trp;Val201Met;Asp1270Asn], n=8; p.[Ile148Thr;Ile1023_Val1024del], n=5; p.[Arg117Leu;Leu997Phe], n=6; c.[1210-34TG[12];1210-12T[5];2930C>T], n=3; p.[Arg74Trp;Asp1270Asn], n=4; p.Asp1270Asn, n=2; p.Ile148Thr, n=6; p.Leu997Phe, n=36. In 39 patients, we analysed the CFTR gating activity on NEC in comparison with patients with CF (n=8) and carriers (n=4). Finally, we analysed in vitro the p.[Arg74Trp;Val201Met;Asp1270Asn] complex allele. The p.[Ile148Thr;Ile1023_Val1024del] caused severe CF in five compound heterozygous with a class I-II mutation. Their CFTR activity on NEC was comparable with patients with two class I-II mutations (mean 7.3% vs 6.9%). The p.[Arg74Trp;Asp1270Asn] and the p.Asp1270Asn have scarce functional effects, while p.[Arg74Trp;Val201Met;Asp1270Asn] caused mild CF in four of five subjects carrying a class I-II mutation in trans, or CFTR-related disorders (CFTR-RD) in three having in trans a class IV-V mutation. The p.[Arg74Trp;Val201Met;Asp1270Asn] causes significantly (pT] and a class I-II mutation had mild CF or CFTR-RD (gating activity: 18.5-19.0%). The effect of complex alleles partially depends on the mutation in trans. Although larger studies are necessary, the CFTR activity on NEC is a rapid contributory tool to classify patients with CFTR dysfunction. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  12. Capillary electrophoresis application in metal speciation and complexation characterization

    Science.gov (United States)

    Capillary electrophoresis is amenable to the separation of metal ionic species and the characterization of metal-ligand interactions. This book chapter reviews and discusses three representative case studies in applications of CE technology in speciation and reactions of metal with organic molecules...

  13. Cationic iridium(III) complexes bearing a bis(triazole) ancillary ligand.

    Science.gov (United States)

    Donato, Loïc; Abel, Philippe; Zysman-Colman, Eli

    2013-06-21

    Three new heteroleptic cationic iridium complexes of the form [Ir(C^N)(btl)](+), where btl = 1,1'-benzyl-4,4'-bi-1H-1,2,3-triazolyl and C^N = 2-phenylpyridine (ppyH) (1), 1-benzyl-4-phenyl-1H-1,2,3-triazole (phtl) (2) or 1-benzyl-4-(2,4-difluorophenyl)-1H-1,2,3-triazole (dFphtl) (3), were synthesized and isolated as their hexafluorophosphate (PF6(-)) salts and fully characterized. The single crystal structure of 3 has been solved. Along the series from 1-3 the absorption spectra shift hypsochromically while the electrochemical gap increases from 3.25 to 3.54 to 3.88 V. Acetonitrile solutions of 1 and 2 are poorly luminescent, sky-blue emitters with predominant ligand-centered and charge transfer character, respectively. Theoretical calculations support these assignments. Complex 3 is not photostable and decomposes to solvento-based structures of the form [Ir(dFphtl)2(ACN)n](+) (n = 1, 2) through a dissociation and degradation of the btl ligand.

  14. IRMPD action spectroscopy of alkali metal cation-cytosine complexes: effects of alkali metal cation size on gas phase conformation.

    Science.gov (United States)

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

    2013-10-01

    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 similar and distinctive spectral features over the range of ~1000-1900 cm(-1). The IRMPD spectra of the Li(+)(cytosine), Na(+)(cytosine), and K(+)(cytosine) complexes are relatively simple but exhibit changes in the shape and shifts in the positions of several bands that correlate with the size of the alkali metal cation. The IRMPD spectra of the Rb(+)(cytosine) and Cs(+)(cytosine) complexes are much richer as distinctive new IR bands are observed, and the positions of several bands continue to shift in relation to the size of the metal cation. The measured IRMPD spectra are compared to linear IR spectra of stable low-energy tautomeric conformations calculated at the B3LYP/def2-TZVPPD level of theory to identify the conformations accessed in the experiments. These comparisons suggest that the evolution in the features in the IRMPD action spectra with the size of the metal cation, and the appearance of new bands for the larger metal cations, are the result of the variations in the intensities at which these complexes can be generated and the strength of the alkali metal cation-cytosine binding interaction, not the presence of multiple tautomeric conformations. Only a single tautomeric conformation is accessed for all five alkali metal cation-cytosine complexes, where the alkali metal cation binds to the O2 and N3 atoms of the canonical amino-oxo tautomer of cytosine, M(+)(C1).

  15. Origin of eclogite-bearing, domed, layered metamorphic complexes ("core complexes") in the D'entrecasteaux Islands, Papua New Guinea

    Science.gov (United States)

    Davies, Hugh L.; Warren, R. G.

    1988-02-01

    Compositionally layered metamorphic rocks of the D'Entrecasteaux Islands, Papua New Guinea, are folded into domes and antiforms bounded by faults parallel to metamorphic layering and foliation. The structures are broadly similar to the metamorphic "core complexes" of western North America. Lenses of ultramafic rock lie on the bounding faults, and the same faults have served as loci for Quaternary andesitic volcanic activity. Metamorphic grade in the northern islands (Goodenough and Fergusson) is amphibolite facies, with pockets of eclogite (Fergusson Island only) and granulite, and is greenschist facies in the southern island (Normanby). In all three islands there is a characteristic tectonostratigraphic sequence (FMU sequence) from felsic metamorphic rocks at base, or internally, through mafic metamorphic rocks to ultramafic rocks at top, or externally. The association of metamorphic and ultramafic rocks apparently developed in a north dipping Paleogene subduction system and was exhumed to upper crustal level in the Oligocene--Early Miocene, possibly by reversal of movement on faults in the former subduction system. Vigorous uplift and development of domes and antiforms in the Pliocene was triggered by westward propagation of the Woodlark Basin spreading ridge and was accompanied by rifting, rift-related magmatism, rapid erosion, and deposition of coarse sediment in the adjacent Trobriand Basin.

  16. Synthesis, characterization, anti-microbial, DNA binding and cleavage studies of Schiff base metal complexes

    Directory of Open Access Journals (Sweden)

    Poomalai Jayaseelan

    2016-09-01

    Full Text Available A novel Schiff base ligand has been prepared by the condensation between butanedione monoxime with 3,3′-diaminobenzidine. The ligand and metal complexes have been characterized by elemental analysis, UV, IR, 1H NMR, conductivity measurements, EPR and magnetic studies. The molar conductance studies of Cu(II, Ni(II, Co(II and Mn(II complexes showed non-electrolyte in nature. The ligand acts as dibasic with two N4-tetradentate sites and can coordinate with two metal ions to form binuclear complexes. The spectroscopic data of metal complexes indicated that the metal ions are complexed with azomethine nitrogen and oxyimino nitrogen atoms. The binuclear metal complexes exhibit octahedral arrangements. DNA binding properties of copper(II metal complex have been investigated by electronic absorption spectroscopy. Results suggest that the copper(II complex bind to DNA via an intercalation binding mode. The nucleolytic cleavage activities of the ligand and their complexes were assayed on CT-DNA using gel electrophoresis in the presence and absence of H2O2. The ligand showed increased nuclease activity when administered as copper complex and copper(II complex behave as efficient chemical nucleases with hydrogen peroxide activation. The anti-microbial activities and thermal studies have also been studied. In anti-microbial activity all complexes showed good anti-microbial activity higher than ligand against gram positive, gram negative bacteria and fungi.

  17. Theoretical characterization and design of highly efficient iridium (III) complexes bearing guanidinate ancillary ligand.

    Science.gov (United States)

    Ren, Xin-Yao; Wu, Yong; Wang, Li; Zhao, Liang; Zhang, Min; Geng, Yun; Su, Zhong-Min

    2014-06-01

    A density functional theory/time-depended density functional theory was used to investigate the synthesized guanidinate-based iridium(III) complex [(ppy)2Ir{(N(i)Pr)2C(NPh2)}] (1) and two designed derivatives (2 and 3) to determine the influences of different cyclometalated ligands on photophysical properties. Except the conventional discussions on geometric relaxations, absorption and emission properties, many relevant parameters, including spin-orbital coupling (SOC) matrix elements, zero-field-splitting parameters, radiative rate constants (kr) and so on were quantitatively evaluated. The results reveal that the replacement of the pyridine ring in the 2-phenylpyridine ligand with different diazole rings cannot only enlarge the frontier molecular orbital energy gaps, resulting in a blue-shift of the absorption spectra for 2 and 3, but also enhance the absorption intensity of 3 in the lower-energy region. Furthermore, it is intriguing to note that the photoluminescence quantum efficiency (ΦPL) of 3 is significantly higher than that of 1. This can be explained by its large SOC value(n=3-4) and large transition electric dipole moment (μS3), which could significantly contribute to a larger kr. Besides, compared with 1, the higher emitting energy (ET1) and smaller (2) value for 3 may lead to a smaller non-radiative decay rate. Additionally, the detailed results also indicate that compared to 1 with pyridine ring, 3 with imidazole ring performs a better hole injection ability. Therefore, the designed complex 3 can be expected as a promising candidate for highly efficient guanidinate-based phosphorescence emitter for OLEDs applications. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Synthesis, Structure, and Anticancer Activity of Arene-Ruthenium(II) Complexes with Acylpyrazolones Bearing Aliphatic Groups in the Acyl Moiety.

    Science.gov (United States)

    Palmucci, Jessica; Marchetti, Fabio; Pettinari, Riccardo; Pettinari, Claudio; Scopelliti, Rosario; Riedel, Tina; Therrien, Bruno; Galindo, Agustin; Dyson, Paul J

    2016-11-21

    A series of neutral ruthenium(II) arene complexes [(arene)Ru(Q(R))Cl] (arene = p-cymene (cym) or hexamethylbenzene (hmb)) containing 4-acyl-5-pyrazolonate Q(R) ligands with different electronic and steric substituents (R = 4-cyclohexyl, 4-stearoyl, or 4-adamantyl) and related ionic complexes [(arene)Ru(Q(R))(PTA)][PF6] (PTA = 1,3,5-triaza-7-phosphaadamantane) were synthesized and characterized by spectroscopy (IR, UV-vis, ESI-MS, and (1)H and (13)C NMR), elemental analysis, X-ray crystallography, and density functional theory studies. The cytotoxicity of the proligands and metal complexes was evaluated in vitro against human ovarian carcinoma cells (A2780 and A2780cisR), as well as against nontumorous human embryonic kidney (HEK293) cells. In general the cationic PTA-containing complexes are more cytotoxic than their neutral precursors with a chloride ligand in place of the PTA. Moreover, the complexes do not show cross-resistance and are essentially equally cytotoxic to both the A2780 and A2780cisR cell lines, although they only show limited selectivity toward the cancer cell lines.

  19. A biomimicing approach to the mixed ligand complexes of bivalent transition metal

    Directory of Open Access Journals (Sweden)

    Bipin Bihari Prasad

    2013-03-01

    Full Text Available Metal complexes of the type ML1L2[M=Cu(II, Ni(II, and Co(II, L1=,'-dipyridyl(dipy., L2=2-hydroxybenzalidine anthranilic acid (HBAA] have been synthesized by using ,'-dipyridyl(dipy., 2-hdroxybenzalidine anthranilic acid (HBAA and metal(II acetate. The resulting mixed ligand metal complexes have been characterized on the basis of elemental analysis, IR-spectra, electronic spectra, magnetic susceptibilities and molar conductance measurements. The antifungal and antibacterial activities of ligands and there metal complexes have been screened against Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Escherichia coli and Staphylococcus aureus.

  20. Hydrogen storage in metal hydrides and complex hydrides; Wasserstoffspeicherung in Metall- und komplexen Hydriden - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Bielmann, M.; Zuettel, A.

    2007-07-01

    This final report for the Swiss Federal Office of Energy (SFOE), reports on work done in 2007 at the Swiss Federal Laboratories for Materials Science and Technology EMPA on the storage of hydrogen in metal hydrides and complex hydrides. In particular, the use of tetrahydroborates is noted. The potential of this class of materials is stressed. The structures at room-temperature were examined using neutron and X-ray diffraction methods. Thermodynamic methods helped determine the thermodynamic stability of the materials. Also, a complete energy diagram for the materials was developed. The use of silicon oxide to reduce activation energy and its catalytic effects are discussed. The challenges placed by desorption mechanisms are noted. The authors note that reversibility is basically proven.

  1. Complexation with dissolved organic matter and solubility control of heavy metals in sandy soil

    NARCIS (Netherlands)

    Weng, L.; Temminghoff, E.J.M.; Lofts, S.; Tipping, E.; Riemsdijk, van W.H.

    2002-01-01

    The complexation of heavy metals with dissolved organic matter (DOM) in the environment influences the solubility and mobility of these metals. In this paper, we measured the complexation of Cu, Cd, Zn, Ni, and Pb with DOM in the soil solution at pH 3.7-6.1 using a Donnan membrane technique. The res

  2. Complex transition metal hydrides: linear correlation of countercation electronegativity versus T-D bond lengths.

    Science.gov (United States)

    Humphries, T D; Sheppard, D A; Buckley, C E

    2015-06-30

    For homoleptic 18-electron complex hydrides, an inverse linear correlation has been established between the T-deuterium bond length (T = Fe, Co, Ni) and the average electronegativity of the metal countercations. This relationship can be further employed towards aiding structural solutions and predicting physical properties of novel complex transition metal hydrides.

  3. The metal-tool contact friction at the ultrasonic vibration drawing of ball-bearing steel wires

    Directory of Open Access Journals (Sweden)

    Susan, Mihai

    1999-12-01

    Full Text Available The friction reversion mechanism during the ultrasonic vibration drawing (UVD of wires has been detailed for the case when the die is located at the oscillation maxima of the waves and actuated parallel to the friction force direction. The decrease of the drawing force for the UVD technology as compared to classical drawing has been explained by means of the intermittent contact in the metal-die forming area. A relationship has been derived for the UVD friction coefficient, μUS that allowed the analytical determination of the drawing force. In the case of the Romanian RUL 1V (AISI 52100 ball bearing steel wires, a good agreement has been found between the analytical and the experimental values of the drawing forces that have decreased, as compared to classical drawing, by more than 5 % for drawing rates lower than 0.66m/s.

    Se hace un análisis pormenorizado del mecanismo de reversión de la fricción al estirado por vibraciones ultrasonoras (EVU de los alambres, para el caso en que la trefiladora está ubicada en los máximos de oscilación de las ondas y activada paralelamente a la dirección de estirado. La disminución de la fuerza de estirado para la tecnología EVU en comparación con el estirado clásico, se ha explicado a través del contacto intermitente en el área de deformación metal-herramienta. Se halló una relación para el coeficiente de fricción EVU, μUS que permitió la determinación analítica de la fuerza de estirado. En el caso de los alambres de acero rumano de rodamientos RUL 1V (AISI 52100 se encontró una justa concordancia entre los valores analítico y experimental de la fuerza de estirado que, en comparación con los de estirado clásico, se encontraron disminuidos en más de un 5 % para velocidades de estirado menores de 0,66m/s.

  4. Synthesis and Isomeric Analysis of Ru(II) Complexes Bearing Pentadentate Scaffolds.

    Science.gov (United States)

    Gil-Sepulcre, Marcos; Axelson, Jordan C; Aguiló, Joan; Solà-Hernández, Lluís; Francàs, Laia; Poater, Albert; Blancafort, Lluís; Benet-Buchholz, Jordi; Guirado, Gonzalo; Escriche, Lluís; Llobet, Antoni; Bofill, Roger; Sala, Xavier

    2016-11-07

    A Ru(II)-pentadentate polypyridyl complex [Ru(II)(κ-N(5)-bpy2PYMe)Cl](+) (1(+), bpy2PYMe = 1-(2-pyridyl)-1,1-bis(6-2,2'-bipyridyl)ethane) and its aqua derivative [Ru(II)(κ-N(5)-bpy2PYMe)(H2O)](2+) (2(2+)) were synthesized and characterized by experimental and computational methods. In MeOH, 1(+) exists as two isomers in different proportions, cis (70%) and trans (30%), which are interconverted under thermal and photochemical conditions by a sequence of processes: chlorido decoordination, decoordination/recoordination of a pyridyl group, and chlorido recoordination. Under oxidative conditions in dichloromethane, trans-1(2+) generates a [Ru(III)(κ-N(4)-bpy2PYMe)Cl2](+) intermediate after the exchange of a pyridyl ligand by a Cl(-) counterion, which explains the trans/cis isomerization observed when the system is taken back to Ru(II). On the contrary, cis-1(2+) is in direct equilibrium with trans-1(2+), with absence of the κ-N(4)-bis-chlorido Ru(III)-intermediate. All these equilibria were modeled by density functional theory calculations. Interestingly, the aqua derivative is obtained as a pure trans-[Ru(II)(κ-N(5)-bpy2PYMe)(H2O)](2+) isomer (trans-2(2+)), while the addition of a methyl substituent to a single bpy of the pentadentate ligand leads to the formation of a single cis isomer for both chlorido and aqua derivatives [Ru(II)(κ-N(5)-bpy(bpyMe)PYMe)Cl](+) (3(+)) and [Ru(II)(κ-N(5)-bpy(bpyMe)PYMe)(H2O)](2+) (4(2+)) due to the steric constraints imposed by the modified ligand. This system was also structurally and electrochemically compared to the previously reported [Ru(II)(PY5Me2)X](n+) system (X = Cl, n = 1 (5(+)); X = H2O, n = 2 (6(2+))), which also contains a κ-N(5)-Ru(II) coordination environment, and to the newly synthesized [Ru(II)(PY4Im)X](n+) complexes (X = Cl, n = 1 (7(+)); X = H2O, n = 2 (8(2+))), which possess an electron-rich κ-N(4)C-Ru(II) site due to the replacement of a pyridyl group by an imidazolic carbene.

  5. Heterobimetallic coordination polymers involving 3d metal complexes and heavier transition metals cyanometallates

    Energy Technology Data Exchange (ETDEWEB)

    Peresypkina, Eugenia V. [Nikolaev Institute of Inorganic Chemistry, SB RAS, Novosibirsk 630090 (Russian Federation); Samsonenko, Denis G. [Nikolaev Institute of Inorganic Chemistry, SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Vostrikova, Kira E., E-mail: vosk@niic.nsc.ru [Nikolaev Institute of Inorganic Chemistry, SB RAS, Novosibirsk 630090 (Russian Federation); LMI, Université Claude Bernard Lyon 1, 69622 Villeurbanne Cedex (France)

    2015-04-15

    The results of the first steps in the design of coordination polymers based on penta- and heptacyanometallates of heavier d transitions metals are presented. The 2D structure of the coordination polymers: [(Mn(acacen)){sub 2}Ru(NO)(CN){sub 5}]{sub n} and two complexes composed of different cyanorhenates, [Ni(cyclam)]{sub 2}[ReO(OH)(CN){sub 4}](ClO{sub 4}){sub 2}(H{sub 2}O){sub 1.25} and [Cu(cyclam)]{sub 2}[Re(CN){sub 7}](H{sub 2}O){sub 12}, was confirmed by single crystal XRD study, the rhenium oxidation state having been proved by the magnetic measurements. An amorphism of [M(cyclam)]{sub 3}[Re(CN){sub 7}]{sub 2} (M=Ni, Cu) polymers does not allow to define strictly their dimensionality and to model anisotropic magnetic behavior of the compounds. However, with high probability a honey-comb like layer structure could be expected for [M(cyclam)]{sub 3}[Re(CN){sub 7}]{sub 2} complexes, studied in this work, because such an arrangement is the most common among the bimetallic assemblies of hexa- and octacyanometallates with a ratio [M(cyclam)]/[M(CN){sub n}]=3/2. For the first time was prepared and fully characterized a precursor (n-Bu{sub 4}N){sub 2}[Ru(NO)(CN){sub 5}], soluble in organic media. - Graphical abstract: The very first results in the design of 2D coordination polymers based on penta- and heptacyanometallates of 4d and5d transitions metals are presented. - Highlights: • Design of coordination polymers based on penta- and heptacyanometallates. • New Ru and Re cyanide based heterobimetallic coordination complexes. • Hydrolysis and ox/red processes involving [Re(CN){sub 7}]{sup 3+} during crystallization. • High magnetic anisotropy of [M(cyclam)]{sub 3}[Re(CN){sub 7}]{sub 2}(H{sub 2}O){sub n}, M=Cu, Ni, complexes.

  6. Metallic complexes with glyphosate: a review; Complexos metalicos com o herbicida glifosato: revisao

    Energy Technology Data Exchange (ETDEWEB)

    Coutinho, Claudia F.B.; Mazo, Luiz Henrique [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Quimica]. E-mail: claudiabreda@iqsc.usp.br

    2005-11-15

    We present studies involving metallic ions and the herbicide glyphosate. The metallic complexes of Cu(II), Zn(II), Mn(II), Ni(II), Cd(II), Pb(II), Cr(III), Fe(III), Co(III), ammonium, sodium, Ag(I), alkaline earth metals and of some lanthanides ions are described. The complexes are discussed in terms of their synthesis, identification, stability and structural properties, based on data from the current literature. (author)

  7. On the study of the Metal-complex Dye Polyurethane Ionomer

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ The reaction of toluene diisocyanate with polyester, dimethylol propionic acid, metal-complex dye and other additives to form the structure of metal-complex dye polyurethane ionomer molecule has been proven by FT-IR spectra. In aqueous solution, the surface tension of metal-complex dye polyurethane ionomer molecule is seen to slightly increase with increasing concentrtion of metal-complex dye and neopentyl glycol, respectively. This is because the adsorption of hydrophobics of ionomer molecules at the surface of aqueous solution becomes even more order. Under the same experimental condition, the surface tension of metal-complex dye polyurethane ionomer molecule in aqueous solution appears to slightly decrease with increasing NCO/OH ratio, as a result of increased hydrophobics of ionomer molecule adsorbed at the surface of aqueous solution.

  8. On the study of the Metal-complex Dye Polyurethane Ionomer

    Institute of Scientific and Technical Information of China (English)

    WANG; ChengLi

    2001-01-01

    The reaction of toluene diisocyanate with polyester, dimethylol propionic acid, metal-complex dye and other additives to form the structure of metal-complex dye polyurethane ionomer molecule has been proven by FT-IR spectra. In aqueous solution, the surface tension of metal-complex dye polyurethane ionomer molecule is seen to slightly increase with increasing concentrtion of metal-complex dye and neopentyl glycol, respectively. This is because the adsorption of hydrophobics of ionomer molecules at the surface of aqueous solution becomes even more order. Under the same experimental condition, the surface tension of metal-complex dye polyurethane ionomer molecule in aqueous solution appears to slightly decrease with increasing NCO/OH ratio, as a result of increased hydrophobics of ionomer molecule adsorbed at the surface of aqueous solution.  ……

  9. Metals complexation with humic acids in surface water of different natural–climatic zones

    OpenAIRE

    Dinu M. I.

    2013-01-01

    Humic acids extracted from different soils. The stability constants of metal humates and acid dissociation constant humic acids were calculated. Forms of metals in natural waters was determined with use account their chemical composition and content and properties of organic matter. We assessed metals speciation in water objects with account for competitive reactions resulting in formation of hydroxide, hydrocarbonate, sulfate, and chloride metal complexes and obtained a competitive series of...

  10. Compartmentation and complexation of metals in hyperaccumulator plants

    OpenAIRE

    Barbara eLeitenmaier; Hendrik eKüpper

    2013-01-01

    Hyperaccumulators are being intensely investigated. They are not only interesting in scientific context due to their “strange” behavior in terms of dealing with high concentrations of metals, but also because of their use in phytoremediation and phytomining, for which understanding the mechanisms of hyperaccumulation is crucial. Hyperaccumulators naturally use metal accumulation as a defense against herbivores and pathogens, and therefore deal with accumulated metals in very specific ways of ...

  11. Tetracyclines metal complexation: Significance and fate of mutual existence in the environment.

    Science.gov (United States)

    Pulicharla, Rama; Hegde, Krishnamoorthy; Brar, Satinder Kaur; Surampalli, Rao Y

    2017-02-01

    Concern over tetracyclines (TCs) complexation with metals in the environment is growing as a new class of emerging contaminants. TCs exist as a different net charged species depending on their dissociation constants, pH and the surrounding environment. One of the key concerns about TCs is its strong tendency to interact with various metal ions and form metal complexes. Moreover, co-existence of TCs and metals in the environment and their interactions has shown increased antibiotic resistance. Despite extensive research on TCs complexation, investigations on their antibiotic efficiency and pharmacological profile in bacteria have been limited. In addition, the current knowledge on TCs metal complexation, their fate and risk assessment in the environment are inadequate to obtain a clear understanding of their consequences on living systems. This indicates that vital and comprehensive studies on TCs-metal complexation, especially towards growing antibiotic resistance trends are required. This review summarizes the role of TCs metal complexation on the development of antibiotic resistance. Furthermore, impact of metal complexation on degradation, toxicity and the fate of TCs in the environment are discussed and future recommendations have been made.

  12. Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes

    Science.gov (United States)

    Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M. Arif

    2016-05-01

    We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica.

  13. Comparative Study of Aluminum Complexes Bearing N,O- and N,S-Schiff Base in Ring-Opening Polymerization of ε-Caprolactone and L-Lactide.

    Science.gov (United States)

    Chang, Meng-Chih; Lu, Wei-Yi; Chang, Heng-Yi; Lai, Yi-Chun; Chiang, Michael Y; Chen, Hsing-Yin; Chen, Hsuan-Ying

    2015-12-07

    A series of Al complexes bearing Schiff base and thio-Schiff base ligands were synthesized, and their application for the ring-opening polymerization of ε-caprolactone (CL) and l-lactide (LA) was studied. It was found that steric effects of the ligands caused higher polymerization rate and most importantly the Al complexes with N,S-Schiff base showed significantly higher polymerization rate than Al complexes with N,O-Schiff base (5-12-fold for CL polymerization and 2-7-fold for LA polymerization). The reaction mechanism of CL polymerization was investigated by density functional theory (DFT). The calculations predicted a lower activation energy for a process involved with an Al complex bearing an N,S-Schiff base ligand (17.6 kcal/mol) than for that of an Al complex bearing an N,O-Schiff base ligand (19.0 kcal/mol), and this magnitude of activation energy reduction is comparable to the magnitude of rate enhancement observed in the experiment. The reduction of activation energy was attributed to the catalyst-substrate destabilization effect. Using a sulfur-containing ligand to decrease the activation energy in the ring-opening polymerization process may be a new strategy to design a new Al complex with high catalytic activity.

  14. CD Spectroscopic Study on the Molecular Recognition of Chiral Salen-Metal Complexes

    Institute of Scientific and Technical Information of China (English)

    刘涛; 阮文娟; 南晶; 朱志昂

    2003-01-01

    The molecular recognition behavior of the chiral salen-metal complexes towards guest molecules, such as imidazole derivatives and amino-acid ester, was systematically investigated by means of circular dichroism (CD) spectra. The coordination numbers of the host-guest complexes as well as the recognition capability of the salen-metal complexes were explained by character and intensity analyses of the CD spectra.

  15. Exploring the role of pendant amines in transition metal complexes for the reduction of N2 to hydrazine and ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Papri; Prokopchuk, Demyan E.; Mock, Michael T.

    2017-03-01

    This review examines the synthesis and acid reactivity of transition metal dinitrogen complexes bearing diphosphine ligands containing pendant amine groups in the second coordination sphere. This manuscript is a review of the work performed in the Center for Molecular Electrocatalysis. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy (U.S. DOE), Office of Science, Office of Basic Energy Sciences. EPR studies on Fe were performed using EMSL, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at PNNL. Computational resources were provided by the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. Pacific Northwest National Laboratory is operated by Battelle for the U.S. DOE.

  16. Structure, adsorption and magnetic properties of chiral metal-organic frameworks bearing linear trinuclear secondary building blocks.

    Science.gov (United States)

    Chen, Zilu; Liu, Xianlin; Zhang, Chuanbing; Zhang, Zhong; Liang, Fupei

    2011-03-07

    The reactions of new chiral organic ligands trimesoyltri(L-alanine) (L-TMTAH(3)) or trimesoyltri(D-alanine) (D-TMTAH(3)) with transition metal salts in the presence of an ancillary ligand of 4,4'-bipyridine gave two pairs of three dimensional frameworks [Co(3)(L-TMTA)(2)(4,4'-bpy)(4)]·28H(2)O (1), [Co(3)(D-TMTA)(2)(4,4'-bpy)(4)]·28H(2)O (2) [Ni(3)(L-TMTA)(2)(4,4'-bpy)(4)]·2C(2)H(5)OH·14H(2)O (3) and [Ni(3)(D-TMTA)(2)(4,4'-bpy)(4)]·2C(2)H(5)OH·14H(2)O (4). These compounds were characterized by elemental analysis, IR, and X-ray powder diffraction analysis and the structures of 1-3 were determined from X-ray single crystal diffraction analysis. Complexes 1-4 feature linear trinuclear secondary building blocks [M(3)(COO)(4)](2+) formed via the connection of three metal ions by four carboxylato groups from four TMTA(3-) ligands. Every adjacent two linear trinuclear secondary building blocks are linked by one and three 4,4'-bipyridine molecules along the a and c axis, respectively, to form two-dimensional sheets, which are further connected by TMTA(3-) ligands to construct a porous three dimensional framework with one-dimensional channels. Compound 3 was taken as an example to investigate the adsorption properties of compounds 1-4. It revealed a saturated hydrogen uptake of 216.6 cm(3) g(-1) (2.0 wt%) at 11.1 atm measured at 77 K, a maximum CO(2) uptake of 119.4 cm(3) g(-1) (23.5 wt%) at 19.5 atm measured at 298 K and a saturated CH(4) uptake of 77.8 cm(3) g(-1) (5.6 wt%) at 27.1 atm measured at 298 K. The magnetic studies of complexes 1 and 3 indicate the presence of antiferromagnetic interactions between the metal ions in the two compounds.

  17. Process for the displacement of cyanide ions from metal-cyanide complexes

    Science.gov (United States)

    Smith, Barbara F.; Robinson, Thomas W.

    1997-01-01

    The present invention relates to water-soluble polymers and the use of such water-soluble polymers in a process for the displacement of the cyanide ions from the metal ions within metal-cyanide complexes. The process waste streams can include metal-cyanide containing electroplating waste streams, mining leach waste streams, mineral processing waste streams, and related metal-cyanide containing waste streams. The metal ions of interest are metals that give very strong complexes with cyanide, mostly iron, nickel, and copper. The physical separation of the water-soluble polymer-metal complex from the cyanide ions can be accomplished through the use of ultrafiltration. Once the metal-cyanide complex is disrupted, the freed cyanide ions can be recovered for reuse or destroyed using available oxidative processes rendering the cyanide nonhazardous. The metal ions are released from the polymer, using dilute acid, metal ion oxidation state adjustment, or competing chelating agents, and collected and recovered or disposed of by appropriate waste management techniques. The water-soluble polymer can then be recycled. Preferred water-soluble polymers include polyethyleneimine and polyethyleneimine having a catechol or hydroxamate group.

  18. Modelling of trace metal uptake by roots taking into account complexation by exogenous organic ligands

    Science.gov (United States)

    Jean-Marc, Custos; Christian, Moyne; Sterckeman, Thibault

    2010-05-01

    The context of this study is phytoextraction of soil trace metals such as Cd, Pb or Zn. Trace metal transfer from soil to plant depends on physical and chemical processes such as minerals alteration, transport, adsorption/desorption, reactions in solution and biological processes including the action of plant roots and of associated micro-flora. Complexation of metal ions by organic ligands is considered to play a role on the availability of trace metals for roots in particular in the event that synthetic ligands (EDTA, NTA, etc.) are added to the soil to increase the solubility of the contaminants. As this role is not clearly understood, we wanted to simulate it in order to quantify the effect of organic ligands on root uptake of trace metals and produce a tool which could help in optimizing the conditions of phytoextraction.We studied the effect of an aminocarboxilate ligand on the absorption of the metal ion by roots, both in hydroponic solution and in soil solution, for which we had to formalize the buffer power for the metal. We assumed that the hydrated metal ion is the only form which can be absorbed by the plants. Transport and reaction processes were modelled for a system made up of the metal M, a ligand L and the metal complex ML. The Tinker-Nye-Barber model was adapted to describe the transport of solutes M, L and ML in the soil and absorption of M by the roots. This allowed to represent the interactions between transport, chelating reactions, absorption of the solutes at the root surface, root growth with time, in order to simulate metal uptake by a whole root system.Several assumptions were tested such as i) absorption of the metal by an infinite sink and according to a Michaelis-Menten kinetics, solutes transport by diffusion with and without ii) mass flow and iii) soil buffer power for the ligand L. In hydroponic solution (without soil buffer power), ligands decreased the trace metal flux towards roots, as they reduced the concentration of hydrated

  19. Synthesis and characterization of transition metal(II) complexes with tridentate schiff base in DMF solution

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jeong Geun [Seonam Univ., Namwon (Korea, Republic of); Choi, Yong Kook [Cheonnam National Univ., Kwangju (Korea, Republic of)

    1999-10-01

    Shiff Base ligand such as (NOIPH) have been synthesized from 2-hydroxy-1naph-thaldehyde and arometic amine, Co(II), Ni(II), and Cu(II) complexes from the reaction metal salts with Tridentate Schiff Base (NOIPH) were synthesized. The ligand and metal(II) complexes were characterized by the elementary analysis, IR, UV-Vis, NMR spectra, and thermogravimetric analysis. Metal(II) complexes in solid state have been shown that the mole ratio of Schiff base (NOIPH) as N{sub 2}O type to Metal(II) is 2:1 and the metal(II) complexes of N{sub 2}O ligand type were four-coordinated configurations.

  20. Multiheteromacrocycles that Complex Metal Ions. Sixth Progress Report, 1 May 1979-30 April 1980

    Science.gov (United States)

    Cram, D. J.

    1980-01-15

    Objective is to design synthesize, and evaluate cyclic and polycyclic host organic compounds for their abilities to complex and lipophilize guest metal ions, their complexes, and their clusters. Host organic compounds consist of strategically placed solvating, coordinating, and ion-pairing sites tied together by covalent bonds through hydrocarbon units around cavities shaped to be occupied by guest metal ions or by metal ions plus their ligands. Specificity in complexation is sought by matching the following properties of host and guest: cavity and metal ion sizes; geometric arrangements of binding sites; number of binding sites; character of binding sites; and valences. During this period, hemispherands based on an aryloxy or cyclic urea unit, spherands based on aryloxyl units only, and their complexes with alkali metals and alkaline earths were investigated. An attempt to separate {sup 6}Li and {sup 7}Li by gel permeation chromatography of lithiospherium chloride failed. (DLC)

  1. Design, synthesis, structural elucidation, pharmacological evaluation of metal complexes with pyrazoline derivatives.

    Science.gov (United States)

    Muneera, M Sirajul; Joseph, J

    2016-10-01

    A bioactive pyrazoline derivatives have been synthesized by the base-catalyzed Claisen-Schmidt condensation of imidazole-2-carboxaldehyde with 1-acetyl-2-hydroxynaphthalene followed by cyclization with phenylhydrazine (L(1))/2,3-dimethylphenylhydrazine (L(2)) and 3-nitrophenylhydrazine (L(3)). The metal(II) complexes [Ni(II), Co(II), Cu(II) and Zn(II)] were formed by reacting the corresponding metal acetates with the ligands. All complexes were characterized by elemental analyses, electronic, IR, NMR, mass and ESR spectroscopic techniques. The synthesized metal complexes of pyrazoline compounds showed significant antibacterial activity against the organisms Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Proteus mirabilis and Salmonella typhii when compared with the standard antibiotic (Streptomycin). The ligands and their metal complexes were screened for antioxidant activity using DPPH radical scavenging and superoxide radical scavenging assay methods. All the complexes showed good free radical scavenging activity which is comparable to that of the standards. Among the metal complexes, the copper complex has showed higher activity. The results were indicated that 2-pyrazoline (structural core) and copper ion could be responsible for the potential candidate eliciting antioxidant activity. All compounds were evaluated for their in vitro antimycobacterial activity against Mycobacterium tuberculosis. The ligands and metal complexes were subjected to fluorescence properties and exhibited that the variable fluorescence emission behavior of complexes. It can be attributed to the combined effect of the substituents and naphthyl structural core present in the ligands.

  2. Engineering metal complexes of chiral pentaazacrowns as privileged reverse-turn scaffolds.

    Science.gov (United States)

    Che, Ye; Brooks, Bernard R; Riley, Dennis P; Reaka, Andrea J H; Marshall, Garland R

    2007-02-01

    Reverse turns are common structural motifs and recognition sites in protein/protein interactions. The design of peptidomimetics is often based on replacing the amide backbone of peptides by a non-peptidic scaffold while retaining the biologic mode of action. This study evaluates the potential of metal complexes of chiral pentaazacrowns conceptually derived by reduction of cyclic pentapeptides as reverse-turn mimetics. The possible conformations of metal complexes of chiral pentaazacrown scaffolds have been probed by analysis of 28 crystal structures complexed with six different metals (Mn, Fe, Co, Ni, Cu, and Zn). The solvated structures as well as the impact of complexation with different metals/oxidation states have been examined with density functional theory (DFT) calculation as explicitly represented by interactions with a single water molecule. The results suggest that most reverse-turn motifs seen in proteins could be mimicked effectively with a subset of metal complexes of chiral pentaazacrown scaffolds with an RMSD of approximately 0.3 A. Due to the relatively fixed orientation of the pendant chiral side groups in these metal complexes, one can potentially elicit information about the receptor-bound conformation of the parent peptide from their binding affinities. The presence of 20 H-atoms on the pentaazacrown ring that could be functionalized as well as the conformational perturbations available from complexation with different metals offer a desirable diversity to probe receptors for reverse-turn recognition.

  3. Spectral, XRD, SEM and biological activities of transition metal complexes of polydentate ligands containing thiazole moiety

    Science.gov (United States)

    Neelakantan, M. A.; Marriappan, S. S.; Dharmaraja, J.; Jeyakumar, T.; Muthukumaran, K.

    2008-11-01

    Metal complexes of o-vanillidene-2-aminobenzothiazole have been prepared and characterized by elemental and spectral (vibrational, electronic, 1H NMR and EPR) data as well as magnetic susceptibility measurements and thermo gravimetric analysis (TG/DTA). The low molar conductance values reveal the non-electrolytic nature of these complexes. The elemental analysis suggests that the stoichiometry to be 1:2 (metal:ligand). Magnetic susceptibility data coupled with electronic spectra suggest that two ligands coordinate to each metal atom by phenolic oxygen and imino nitrogen to form high spin octahedral complex with Co(II), Mn(II) and Ni(II). The fifth and sixth position of metal ion is satisfied with water molecules. The thermal behaviour (TG/DTA) of the synthesised complexes shows that the complexes loss water molecules in the first step followed by decomposition of the ligand. Spin Hamiltonian parameters predict a distorted tetrahedral geometry for the copper complex. XRD and SEM analysis provide the crystalline nature and the morphology of the metal complexes. The in vitro biological activity of the metal chelates is tested against the Gram positive bacteria ( Bacillus amyloliquifacians) and gram negative bacteria ( Pseudomonas species), fungus ( Aspergillus niger) and yeast ( Sacchromyces cereviaceae). Most of the metal chelates exhibited higher biological activities.

  4. Identification of metal species by ESI-MS/MS through release of free metals from the corresponding metal-ligand complexes

    OpenAIRE

    Munkhtsetseg Tsednee; Yu-Chen Huang; Yet-Ran Chen; Kuo-Chen Yeh

    2016-01-01

    Electrospray ionization-mass spectrometry (ESI-MS) is used to analyze metal species in a variety of samples. Here, we describe an application for identifying metal species by tandem mass spectrometry (ESI-MS/MS) with the release of free metals from the corresponding metal–ligand complexes. The MS/MS data were used to elucidate the possible fragmentation pathways of different metal–deoxymugineic acid (–DMA) and metal–nicotianamine (–NA) complexes and select the product ions with highest abunda...

  5. Tribology of alternative bearings.

    Science.gov (United States)

    Fisher, John; Jin, Zhongmin; Tipper, Joanne; Stone, Martin; Ingham, Eileen

    2006-12-01

    The tribological performance and biological activity of the wear debris produced has been compared for highly cross-linked polyethylene, ceramic-on-ceramic, metal-on-metal, and modified metal bearings in a series of in vitro studies from a single laboratory. The functional lifetime demand of young and active patients is 10-fold greater than the estimated functional lifetime of traditional polyethylene. There is considerable interest in using larger diameter heads in these high demand patients. Highly cross-linked polyethylene show a four-fold reduction in functional biological activity. Ceramic-on-ceramic bearings have the lowest wear rates and least reactive wear debris. The functional biological activity is 20-fold lower than with highly cross-linked polyethylene. Hence, ceramic-on-ceramic bearings address the tribological lifetime demand of highly active patients. Metal-on-metal bearings have substantially lower wear rates than highly cross-linked polyethylene and wear decreases with head diameter. Bedding in wear is also lower with reduced radial clearance. Differential hardness ceramic-on-metal bearings and the application of ceramic-like coatings reduce metal wear and ion levels.

  6. Transition metal complexes with oxygen donor ligands: a synthesis, spectral, thermal and antimicrobial study

    Directory of Open Access Journals (Sweden)

    VAIBHAV N. PATANGE

    2008-10-01

    Full Text Available Transition metal complexes of chalcones derived from the conden¬sation of 3-acetyl-6-methyl-2H-pyran-2,4(3H-dione (dehydroacetic acid and p-methoxybenzaldehyde (HL1 or p-nitrobenzaldehyde (HL2 were synthesized and characterized by elemental analysis, conductometry, thermal analysis, magnetic measurements, IR, 1H-NMR, UV–Vis spectroscopy and a microbial study. From the analytical and thermal data, the stoichiometry of the complexes was found to be 1:2 (metal:ligand. The molar conductance data revealed that all the metal chelates were non-electrolytes. The thermal stability of the complexes was studied by thermogravimetry and the decomposition schemes of the complexes are given. The ligands and their metal complexes were screened for antibacterial activity against Staphylococcus aureus and Escherichia coli, and fungicidal activity against Aspergillus flavus, Curvularia lunata and Penicillium notatum.

  7. Transition metal complexes supported on metal-organic frameworks for heterogeneous catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Farha, Omar K.; Hupp, Joseph T.; Delferro, Massimiliano; Klet, Rachel C.

    2017-02-07

    A robust mesoporous metal-organic framework comprising a hafnium-based metal-organic framework and a single-site zirconium-benzyl species is provided. The hafnium, zirconium-benzyl metal-organic framework is useful as a catalyst for the polymerization of an alkene.

  8. Supramolecular metal complex systems based on crown-substituted tetrapyrroles

    Energy Technology Data Exchange (ETDEWEB)

    Tsivadze, Aslan Yu [Institute of Physical Chemistry, Russian Academy of Sciences, Moscow (Russian Federation)

    2004-01-31

    The characteristic features of the structures and properties of crown-substituted porphyrinates and phthalocyaninates are considered. Interactions of these compounds with alkali metal salts yield supramolecular ensembles. The factors determining the architecture of such ensembles are described.

  9. Three-way principal component analysis as a tool to evaluate the chemical stability of metal bearing residues from wastewater treatment by the ferrite process.

    Science.gov (United States)

    Pardo, Rafael; Vega, Marisol; Barrado, Enrique; Castrillejo, Yolanda; Sánchez, Isabel

    2013-11-15

    The chemical fractionation patterns of eight metals (Cd, Co, Cu, Cr, Mn, Ni, Pb and Zn) have been determined in 27 metal-bearing residues by using the BCR sequential extraction procedure. The residues were generated as by-products during the optimization of a semi-continuous reactor for metal removal from wastewater based on ferrite synthesis by co-precipitation. The three-dimensional X dataset (samples×metals×fractions) obtained by applying the BCR procedure has been analyzed by multivariate methods: matrix augmentation (MA-PCA) and three-way principal component analysis, 3-PCA (PARAFAC and Tucker3 models). MA-PCA and PARAFAC methods led to two-factor models giving a satisfactory but incomplete picture of the metal fractionation patterns, but the Tucker3 [2,1,2] model allowed to simultaneously describe both the 'pseudo-total' (acid-soluble) contents and the chemical fractionation by means of two non-null interactions g111 and g212 which explain 53.5% and 18.0% of the total variance, respectively. The A-mode loadings of the g212 interaction showed the close relationship between the magnetic character of the solid residues, i.e. the crystalline structure, and the chemical fractionation patterns of the metals resulting from the application of the BCR sequential extraction procedure.

  10. New trends for metal complexes with anticancer activity

    OpenAIRE

    Bruijnincx, Pieter C A; Sadler, P. J.

    2008-01-01

    Medicinal inorganic chemistry can exploit the unique properties of metal ions for the design of new drugs. This has, for instance, led to the clinical application of chemotherapeutic agents for cancer treatment, such as cisplatin. The use of cisplatin is, however, severely limited by its toxic side effects. This has spurred chemists to employ different strategies in the development of new metal-based anticancer agents with different mechanisms of action. Recent trends in the field are discuss...

  11. Asymmetric catalysis mediated by the ligand sphere of octahedral chiral-at-metal complexes.

    Science.gov (United States)

    Gong, Lei; Chen, Liang-An; Meggers, Eric

    2014-10-06

    Due to the relationship between structure and function in chemistry, access to novel chemical structures ultimately drives the discovery of novel chemical function. In this light, the formidable utility of the octahedral geometry of six-coordinate metal complexes is founded in its stereochemical complexity combined with the ability to access chemical space that might be unavailable for purely organic compounds. In this Minireview we wish to draw attention to inert octahedral chiral-at-metal complexes as an emerging class of metal-templated asymmetric "organocatalysts" which exploit the globular, rigid nature and stereochemical options of octahedral compounds and promise to provide new opportunities in the field of catalysis.

  12. New trends in the optical and electronic applications of polymers containing transition-metal complexes.

    Science.gov (United States)

    Liu, Shu-Juan; Chen, Yang; Xu, Wen-Juan; Zhao, Qiang; Huang, Wei

    2012-04-13

    Polymers containing transition-metal complexes exhibit excellent optical and electronic properties, which are different from those of polymers with a pure organic skeleton and combine the advantages of both polymers and metal complexes. Hence, research about this class of polymers has attracted more and more interest in recent years. Up to now, a number of novel polymers containing transition-metal complexes have been exploited, and significant advances in their optical and electronic applications have been achieved. In this article, we summarize some new research trends in the applications of this important class of optoelectronic polymers, such as chemo/biosensors, electronic memory devices and photovoltaic devices.

  13. Metal complexes of curcumin--synthetic strategies, structures and medicinal applications.

    Science.gov (United States)

    Wanninger, Simon; Lorenz, Volker; Subhan, Abdus; Edelmann, Frank T

    2015-08-07

    This Tutorial Review presents an overview on the synthesis, characterization and applications of metal complexes containing curcumin (=1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) and its derivatives as ligands. Innovative synthetic strategies leading to soluble and crystallizable metal curcumin complexes are outlined in detail. Special emphasis is placed on the highly promising and exciting medicinal applications of metal curcumin complexes, with the three most important areas being anticancer activity and selective cytotoxicity, anti-Alzheimer's disease activity, and antioxidative/neuroprotective effects. Overall, this Tutorial Review provides the first general overview of this emerging and rapidly expanding field of interdisciplinary research.

  14. Testing of bearing materials for large two-stroke marine diesel engines

    DEFF Research Database (Denmark)

    Vølund, Anders; Klit, Peder; Persson, Sebastian

    2017-01-01

    In large two-stroke marine diesel engines, bearings are designed to last the lifetime of the engine. The design has shown very good service experiences. The design parameters of the main bearings are, among others, based on the average maximum specific load which the bearing should operate under...... gradient are not established. Large two-stroke journal bearings are not suitable for fatigue test due to the size, the low rotational speed and the complexity of such a test-rig. The disc fatigue test rig was designed with the purpose to test white metal coatings under realistic bearing conditions......, in a confined time-frame. The test-rig simulates a scale model of a thrust bearing, in contrary to standard design, the bearing lining material is applied to the rotating collar. Parameters, such as bearing load, rotational speed, oil temperature, oil contamination is controlled/monitored in order to achieve...

  15. Synthesis, spectral, thermal, potentiometric and antimicrobial studies of transition metal complexes of tridentate ligand

    Directory of Open Access Journals (Sweden)

    Sarika M. Jadhav

    2014-01-01

    Full Text Available A series of metal complexes of Cu(II, Ni(II, Co(II, Fe(III and Mn(II have been synthesized with newly synthesized biologically active tridentate ligand. The ligand was synthesized by condensation of dehydroacetic acid (3-acetyl-6-methyl-(2H pyran-2,4(3H-dione or DHA, o-phenylene diamine and fluoro benzaldehyde and characterized by elemental analysis, molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, 1H-NMR, UV–Vis spectroscopy and mass spectra. From the analytical data, the stoichiometry of the complexes was found to be 1:2 (metal:ligand with octahedral geometry. The molar conductance values suggest the non-electrolyte nature of metal complexes. The IR spectral data suggest that the ligand behaves as a dibasic tridentate ligand with ONN donor atoms sequence towards central metal ion. Thermal behaviour (TG/DTA and kinetic parameters calculated by the Coats–Redfern and Horowitz–Metzger method suggest more ordered activated state in complex formation. To investigate the relationship between stability constants of metal complexes and antimicrobial activity, the dissociation constants of Schiff bases and stability constants of their binary metal complexes have been determined potentiometrically in THF–water (60:40% solution at 25 ± 1 °C and at 0.1 M NaClO4 ionic strength. The potentiometric study suggests 1:1 and 1:2 complexation. Antibacterial and antifungal activities in vitro were performed against Staphylococcus aureus, Escherichia coli and Aspergillus niger, Trichoderma, respectively. The stability constants of the metal complexes were calculated by the Irving–Rosotti method. A relation between the stability constant and antimicrobial activity of complexes has been discussed. It is observed that the activity enhances upon complexation and the order of antifungal activity is in accordance with stability order of metal ions.

  16. Group 3 metal stilbene complexes: Synthesis, reactivity, and electronic structure studies

    OpenAIRE

    Huang, W.; Abukhalil, PM; Khan, SI; Diaconescu, PL

    2014-01-01

    Group 3 metal (E)-stilbene complexes supported by a ferrocene diamide ligand were synthesized and characterized. Reactivity studies showed that they behave similar to analogous naphthalene complexes. Experimental and computational results indicated that the double bond was reduced and not a phenyl ring, in contrast to a previously reported uranium (E)-stilbene complex. © the Partner Organisations 2014.

  17. Impact of ligand protonation on higher-order metal complexation kinetics in aqueous systems

    NARCIS (Netherlands)

    Town, R.M.; Leeuwen, van H.P.

    2008-01-01

    The impact of ligand protonation on the complexation kinetics of higher-order complexes is quantitatively described. The theory is formulated on the basis of the usual situation for metal complex formation in aqueous systems in which the exchange of water for the ligand in the inner coordination sph

  18. Impact of ligand protonation on higher-order metal complexation kinetics in aqueous systems

    NARCIS (Netherlands)

    Town, R.M.; Leeuwen, van H.P.

    2008-01-01

    The impact of ligand protonation on the complexation kinetics of higher-order complexes is quantitatively described. The theory is formulated on the basis of the usual situation for metal complex formation in aqueous systems in which the exchange of water for the ligand in the inner coordination sph

  19. Self-Assembly of Discrete Metal Complexes in Aqueous Solution via Block Copolypeptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Timothy J. Deming

    2013-01-01

    Full Text Available The integration of discrete metal complexes has been attracting significant interest due to the potential of these materials for soft metal-metal interactions and supramolecular assembly. Additionally, block copolypeptide amphiphiles have been investigated concerning their capacity for self-assembly into structures such as nanoparticles, nanosheets and nanofibers. In this study, we combined these two concepts by investigating the self-assembly of discrete metal complexes in aqueous solution using block copolypeptides. Normally, discrete metal complexes such as [Au(CN2]−, when molecularly dispersed in water, cannot interact with one another. Our results demonstrated, however, that the addition of block copolypeptide amphiphiles such as K183L19 to [Au(CN2]− solutions induced one-dimensional integration of the discrete metal complex, resulting in photoluminescence originating from multinuclear complexes with metal-metal interactions. Transmission electron microscopy (TEM showed a fibrous nanostructure with lengths and widths of approximately 100 and 20 nm, respectively, which grew to form advanced nanoarchitectures, including those resembling the weave patterns of Waraji (traditional Japanese straw sandals. This concept of combining block copolypeptide amphiphiles with discrete coordination compounds allows the design of flexible and functional supramolecular coordination systems in water.

  20. First row transition metal complexes of (E)-2-(2-(2-hydroxybenzylidene) hydrazinyl)-2-oxo-N-phenylacetamide complexes

    Science.gov (United States)

    Yousef, T. A.; Abu El-Reash, G. M.; Rakha, T. H.; El-Ayaan, Usama

    2011-12-01

    Manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and chromium(III) complexes of (E)-2-(2-(2-hydroxybenzylidene)hydrazinyl)-2-oxo-N-phenylacetamide were synthesized and characterized by elemental and thermal (TG and DTA) analyses, IR, UV-vis and 1H NMR spectra as well as magnetic moment. Mononuclear complexes are obtained with 1:1 molar ratio except [Mn(HOS) 2(H 2O) 2] and [Co(OS) 2](H 2O) 2 complexes which are obtained with 1:2 molar ratios. The IR spectra of ligand and metal complexes reveal various modes of chelation. The ligand behaves as a monobasic bidentate one and coordination occurs via the enolic oxygen atom and azomethine nitrogen atom. The ligand behaves also as a monobasic tridentate one and coordination occurs through the carbonyl oxygen atom, azomethine nitrogen atom and the hydroxyl oxygen. Moreover, the ligand behaves as a dibasic tridentate and coordination occurs via the enolic oxygen, azomethine nitrogen and the hydroxyl oxygen atoms. The electronic spectra and magnetic moment measurements reveal that all complexes possess octahedral geometry except the copper complexes possesses a square planar geometry. From the modeling studies, the bond length, bond angle, HOMO, LUMO and dipole moment had been calculated to confirm the geometry of the ligands and their investigated complexes. The thermal studies showed the type of water molecules involved in metal complexes as well as the thermal decomposition of some metal complexes. The protonation constant of the ligand and the stability constant of metal complexes were determined pH-metrically in 50% (v/v) dioxane-water mixture at 298 K and found to be consistent with Irving-Williams order. Moreover, the minimal inhibitory concentration (MIC) of these compounds against Staphylococcus aureus, Escherechia coli and Candida albicans were determined.

  1. "Long-range" metal-ligand cooperation in H2 activation and ammonia-promoted hydride transfer with a ruthenium-acridine pincer complex.

    Science.gov (United States)

    Gunanathan, Chidambaram; Gnanaprakasam, Boopathy; Iron, Mark A; Shimon, Linda J W; Milstein, David

    2010-10-27

    The acridine-based pincer complex 1 exhibits an unprecedented mode of metal-ligand cooperation involving a "long-range" interaction between the distal acridine C9 position and the metal center. Reaction of 1 with H(2)/KOH results in H(2) splitting between the Ru center and C9 with concomitant dearomatization of the acridine moiety. DFT calculations show that this process involves the formation of a Ru dihydride intermediate bearing a bent acridine ligand in which C9 is in close proximity to a hydride ligand followed by through-space hydride transfer. Ammonia induces transfer of a hydride from the Ru center of 1 to C9 of the flexible acridine pincer ligand, forming an unusual dearomatized fac-acridine PNP complex.

  2. Structure Characterization and Properties of Metal-Surfactant Complexes Dispersed in Organic Solvents.

    Science.gov (United States)

    de la Iglesia, Pablo; Jaeger, Vance W; Xi, Yuyin; Pfaendtner, Jim; Pozzo, Lilo D

    2015-08-25

    This work describes the synthesis and characterization of metal-surfactant complexes. Dioctyl sulfosuccinate and dodecylbenzenesulfonate are associated with multivalent aluminum, iron, and vanadium ions using an ion exchange reaction. The metal complexes are dispersible in various organic solvents. In solvents with low polarity, the complexes form "inverse" macromolecular structures with multiple metal ions. In contrast, in alcohols, the complex size is reduced, showing a more disperse conformation. The metal and surfactant ions are still strongly bonded to each other in all the solvents probed. Small-angle X-ray and neutron scattering (SAXS and SANS) are used to characterize the structures. Simultaneous fitting of neutron and X-ray scattering spectra is performed in order to obtain an accurate description of the system. Scattering results are also validated by performing molecular dynamics (MD) simulations. The conductive and electrochemical properties of the complexes in solution are also evaluated. The dispersion of metal-organic complexes significantly increases electric conductivity, and some metal ions in the core of the complexes are shown to be electrochemically active in apolar solvents.

  3. Trifluoropropynyl as a surrogate for the cyano ligand and intense, room-temperature, metal-centered emission from its Rh(III) complex.

    Science.gov (United States)

    Sun, Chivin; Thakker, Parth U; Khulordava, Levan; Tobben, Daniel J; Greenstein, Seth M; Grisenti, David L; Kantor, Andrew G; Wagenknecht, Paul S

    2012-10-15

    The trifluoropropynyl ligand -C≡CCF(3) was studied as a possible surrogate for the cyano ligand. Complexes of the type trans-[M(cyclam)(C≡CCF(3))(2)]OTf (where M = Cr(3+), Co(3+), and Rh(3+); OTf = trifluoromethanesulfonate) were prepared and then characterized by electronic spectroscopy and by cyclic voltammetry for the Co(3+) complex. The UV-vis spectra for all three bear a remarkable similarity to that of the trans-M(cyclam)(CN)(2)(+) cations. The trifluoropropynyl complex of Co(3+) shows electrochemical behavior nearly identical with that of its dicyano analogue. Metal-centered phosphorescence from the Rh(III) complex in room-temperature aqueous solution has a quantum yield of 0.12 and a lifetime of 73 μs, nearly 10 times higher than those of its dicyano analogue.

  4. 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

  5. Transition metal complexes of neocryptolepine analogues. Part I: Synthesis, spectroscopic characterization, and invitro anticancer activity of copper(II) complexes

    Science.gov (United States)

    Emam, Sanaa Moustafa; El Sayed, Ibrahim El Tantawy; Nassar, Nagla

    2015-03-01

    New generation of copper(II) complexes with aminoalkylaminoneocryptolepine as bidentate ligands has been synthesized and it is characterized by elemental analyses, magnetic moment, spectra (IR, UV-Vis, 1H NMR and ESR) and thermal studies. The IR data suggest the coordination modes for ligands which behave as a bidentate with copper(II) ion. Based on the elemental analysis, magnetic studies, electronic and ESR data, binuclear square planar geometry was proposed for complexes 7a, 7b, square pyramidal for 9a, 9b and octahedral for 8a, 8b, 10a, 10b. The molar conductance in DMF solution indicates that all complexes are electrolyte except 7a and 7b. The ESR spectra of solid copper(II) complexes in powder form showed an axial symmetry with 2B1g as a ground state and hyperfine structure. The thermal stability and degradation of the ligands and their metal complexes were studied employing DTA and TG methods. The metal-free ligands and their copper(II) complexes were tested for their in vitro anticancer activity against human colon carcinoma (HT-29). The results showed that the synthesized copper(II) complexes exhibited higher anticancer activity than their free ligands. Of all the studied copper(II) complexes, the bromo-substituted complex 9b exhibited high anticancer activity at low micromolar inhibitory concentrations (IC50 = 0.58 μM), compared to the other complexes and the free ligands.

  6. Critical survey of stability constants of EDTA complexes critical evaluation of equilibrium constants in solution stability constants of metal complexes

    CERN Document Server

    Anderegg, G

    2013-01-01

    Critical Survey of Stability Constants of EDTA Complexes focuses on the computations, values, and characteristics of stability constants. The book emphasizes that for a critical discussion of experimentally determined stability constants, it is important to consider the precision of the values that manifests the self-consistency of the constant, taking into consideration the random errors. The publication reviews the stability constants of metal complexes. The numerical calculations affirm the reactions and transformations of metal ions when exposed to varying conditions. The text also present

  7. Alkane oxidation with porphyrins and metal complexes thereof having haloalkyl side chains

    Science.gov (United States)

    Wijesekera, Tilak; Lyons, James E.; Ellis, Jr., Paul E.; Bhinde, Manoj V.

    1998-01-01

    Transition metal complexes of meso-haloalkylporphyrins, wherein the haloalkyl groups contain 2 to 8 carbon atoms have been found to be highly effective catalysts for oxidation of alkanes and for the decomposition of hydroperoxides.

  8. divalent metal complexes of 4-amino-n-pyrimidin-2-ylbenzene ...

    African Journals Online (AJOL)

    Preferred Customer

    use of metal complexes as chemotherapeutic drugs has become a vibrant and growing area of ..... through the pyrimidine nitrogen atom [17]. ... binding can take place by the acceptance of a one pair of electron from the donor nitrogen atom.

  9. Modification of Metal Complex on the Stereoselective Hydrogenation of 2,3-Butanedione

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The modification of some metal complexes on Pt/Al2O3 clusters leads to remarkable increases in both the activity and the selectivity for meso-2,3-butanediol in the stereoselective hydrogenation of 2,3-butanedione.

  10. Influence of phytic acid and its metal complexes on the activity of pectin degrading polygalacturonase.

    Science.gov (United States)

    Asghar, Uzma; Rehman, Haneef Ur; Qader, Shah Ali Ul; Maqsood, Zahida Tasneem

    2013-06-05

    Polygalacturonase is one of the important requirements of different microorganism to cause pathogenicity and spoilage of fruits and vegetables that involved in degradation of pectin during plant tissue infections. In current study, 20 mM phytic acid inhibited 70% activity of polygalacturonase. The effect of different concentration of metal ions such as Cu(+2), Al(+3) and V(+4) were studied separately and it was found that the 20 mM of these metal ions inhibited 37.2%, 79%, and 53% activity of polygalacturonase, respectively. Finally, the complexes of phytic acid and these metals ions were prepared and 1:1 ratio of phytic acid and metal ions complexes showed maximum inhibitory activity of enzyme as compared to complexes having 1:2 and 1:3 ratio except phytate-copper complexes which showed no inhibitory effect on the activity of polygalacturonase.

  11. The diastereoselective synthesis of octahedral cationic iridium hydride complexes with a stereogenic metal centre.

    Science.gov (United States)

    Humbert, Nicolas; Mazet, Clément

    2016-08-23

    We report herein the highly diastereoselective synthesis of octahedral cationic Ir(iii) hydride complexes with a stereogenic metal centre following various strategies. The configurational stability of these compounds has also been investigated.

  12. Effects of Lability of Metal Complex on Free Ion Measurement Using DMT

    NARCIS (Netherlands)

    Weng, L.P.; Riemsdijk, van W.H.; Temminghoff, E.J.M.

    2010-01-01

    Very low concentrations of free metal ion in natural samples can be measured using the Donnan membrane technique (DMT) based on ion transport kinetics. In this paper, the possible effects of slow dissociation of metal complexes on the interpretation of kinetic DMT are investigated both theoretically

  13. Some transition metal complexes derived from mono- and di-ethynyl perfluorobenzenes

    NARCIS (Netherlands)

    Armitt, D.J.; Bruce, M.I.; Gaudio, M.; Zaitseva, N.N.; Skelton, B.W.; White, A.H.; Le Guennic, B.; Halet, J.-F.; Fox, M.A.; Roberts, R.L.; Hartl, F.; Low, P.J.

    2008-01-01

    Transition metal alkynyl complexes containing perfluoroaryl groups have been prepared directly from trimethylsilyl-protected mono- and di-ethynyl perfluoroarenes by simple desilylation/metallation reaction sequences. Reactions between Me3SiC CC6F5 and RuCl(dppe)Cp'[Cp' = Cp, Cp*] in the presence of

  14. Transition Metal Complexes of 5-bromo Salicylaldehyde-2-furoic acid hydrazide; Synthesis and Characterisation

    Directory of Open Access Journals (Sweden)

    MANISH KUMAR

    2012-12-01

    Full Text Available A series of transition metal complexes of the ligand 5-bromo salicylaldehyde-2-furoic acid hydrazide have been prepared using Ti(III, Mn(III, V(III, Co(III, Fe(III, Ru(III and Rh(III. The complexes have been characterized by elemental analyses, melting points, molar conductance, magnetic susceptibility measurement, electronic and infra red spectral studies. Based on these studies octahedral structures have been proposed for these complexes. The ligand has behaved in dibasic tridentate manner. The I.R. spectra of the complexes revealed non-participation of furan ring oxygen in coordination with the metal ions.

  15. Polypyridyl transition metal complexes with application in water oxidation catalysis and dye-sensitised solar cells

    OpenAIRE

    Rudd, Jennifer A.

    2012-01-01

    This thesis contains complementary synthetic and computational studies of transition metal complexes with polypyridyl ligands for use either as water oxidation catalysts or for application in dye-sensitised solar cells (DSSCs). Chapter 1 introduces the reasons for researching water splitting catalysts and describes a number of current techniques used to do so; from photoelectrochemical cells to the use of transition metal polypyridyl complexes. It also introduces three commercially avail...

  16. Coordination of cassava starch to metal ions and thermolysis of resulting complexes

    Directory of Open Access Journals (Sweden)

    Piotr Tomasik

    2003-12-01

    Full Text Available Cassava starch formed Werner-type complexes with ions of metals from the transition groups. This was proven by conductivity and electron paramagnetic resonance measurements. The coordination of starch to central metal ions influenced the thermal decomposition of starch. As a rule complexes started to decompose at lower temperature than did starch. On the other hand, the decomposition proceeded at a lower rate than the decomposition of non-coordinated starch.

  17. Pyridinediimine Iron Complexes with Pendant Redox-Inactive Metals Located in the Secondary Coordination Sphere.

    Science.gov (United States)

    Delgado, Mayra; Ziegler, Joshua M; Seda, Takele; Zakharov, Lev N; Gilbertson, John D

    2016-01-19

    A series of pyridinediimine (PDI) iron complexes that contain a pendant 15-crown-5 located in the secondary coordination sphere were synthesized and characterized. The complex Fe((15c5)PDI)(CO)2 (2) was shown in both the solid state and solution to encapsulate redox-inactive metal ions. Modest shifts in the reduction potential of the metal-ligand scaffold were observed upon encapsulation of either Na(+) or Li(+).

  18. Transition metal M(II complexes with isonicotinoylhydrazone-9-anthraldehyde

    Directory of Open Access Journals (Sweden)

    Dianu M.L.

    2010-01-01

    Full Text Available New complexes of isonicotinoylhydrazone-9-anthraldehyde with Cu(II, Co(II and Ni(II have been prepared and characterized by analytical and physico-chemical techniques, such as elemental and thermal analyses, magnetic susceptibility and conductivity measurements, and electronic, EPR and IR spectral studies. The infrared spectral studies revealed the bidentate or monodentate nature of the Schiff base in the complexes; the pyridine nitrogen does not participate in the coordination. A tetrahedral geometry is suggested for the nitrate-complexes and an octahedral geometry for the others. Thermal studies support the chemical formulation of these complexes.

  19. Synthesis, physico-chemical characterization and biological activity of 2-aminobenzimidazole complexes with different metal ions

    Directory of Open Access Journals (Sweden)

    Podunavac-Kuzmanović Sanja O.

    2004-01-01

    Full Text Available Complexes of 2-aminobenzimidazole (L with nitrates of cobalt(II nickel(II, copper (II, zinc(II and silver(I were synthesized. The molar ratio metal:ligand in the reaction of the complex formation was 1:2. It should be noticed, that the reaction of all the metal salts yielded bis(ligand complexes of the general formula M(L2(NO32 × nH2O (M=Co, Ni Cu, Zn or Ag; n=0, 1, 2 or 6. The complexes were characterized by elemental analysis of the metal, molar conductivity, magnetic susceptibility measurements and IR spectra. Co(II, Ni(II and Cu(II complexes behave as non-electrolytes, whilst Zn(II and Ag(I are 1:1 electrolytes. Cu(II complex has a square-planar stereochemistry, Ag(I complex is linear, whilst the Co(II, Ni(II and Zn(II complexes have a tetrahedral configuration. In all the complexes ligand is coordinated by participation of the pyridine nitrogen of the benzimidazole ring. The antimicrobial activity of the ligand and its complexes against Pseudomonas aeruginosa, Bacillus sp. Staphylococcus aureus and Saccharomyces cerevisiae was investigated. The effect of metal on the ligand antimicrobial activity is discussed.

  20. New trends for metal complexes with anticancer activity

    NARCIS (Netherlands)

    Bruijnincx, P.C.A.; Sadler, Peter J.

    2008-01-01

    Medicinal inorganic chemistry can exploit the unique properties of metal ions for the design of new drugs. This has, for instance, led to the clinical application of chemotherapeutic agents for cancer treatment, such as cisplatin. The use of cisplatin is, however, severely limited by its toxic

  1. New trends for metal complexes with anticancer activity

    NARCIS (Netherlands)

    Bruijnincx, P.C.A.; Sadler, Peter J.

    2008-01-01

    Medicinal inorganic chemistry can exploit the unique properties of metal ions for the design of new drugs. This has, for instance, led to the clinical application of chemotherapeutic agents for cancer treatment, such as cisplatin. The use of cisplatin is, however, severely limited by its toxic side-

  2. Highly active double metal cyanide complexes: Effect of central metal and ligand on reaction of epoxide/CO2

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Various novel double metal cyanide (DMC) catalysts were successfully prepared by modifying the central metal (M) and one of cyanide ion (CN-) in Zna[M(CN)b]c complex. Such modifications have significant impact on the catalytic efficiency as well as the polymer selectivity for the reaction of PO/CO2. Zn-Ni(Ⅱ) DMC is a potential catalyst for alternating copolymerization of PO/CO2,and DMC catalysts based on Zn3[Co(CN)5X]2 (X = Br- and N3-) exhibit moderate efficiency for the production of polycarbonates.This research presents the preliminary exploration of novel DMC complex via chemical modification of its central metal and ligand.(C) 2007 Guo Rong Qi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  3. 3d/4f Metal Complexes of Phenolic Oximes New Binding Sites on Anderson Polyoxometalates Metal Complexes of the New THAME Ligand

    DEFF Research Database (Denmark)

    Sethi, Waqas

    to be coordinatedto SMMs as well as onto other transition metal complexes, via different synthetic strategies. These synthetic routes did not result in the crystallisation of any new compounds. A new hexadentate ligand tris(((2-hydroxyethyl)-amino)methyl)ethane (THAME) was synthesised and characterised. THAME...

  4. The Metallicity of HVC Complex C: Observational Evidence for the Accretion of Low-Metallicity Gas onto the Milky Way

    NARCIS (Netherlands)

    Wakker, Bart P.; Howk, J. Chris; Savage, Blair D.; Tufte, Steve L.; Reynolds, Ron J.; van Woerden, Hugo; Schwarz, Ulrich J.

    1999-01-01

    We present observations of the (field of the) Seyfert galaxy Mark 290, which probes the high-velocity cloud (HVC) complex C, one of the largest HVCs (Wakker & van Woerden 1991). We find that this object has a metallicity of 0.094+/-0.020^{+0.022}_{-0.019} times solar. A semi-theoretical upper limit

  5. Effects of transition metal ion identity and π-cation interactions in metal-bis(peptide) complexes containing phenylalanine.

    Science.gov (United States)

    Utley, Brandon; Angel, Laurence A

    2010-01-01

    Electrospray ionization-tandem mass spectrometry was used to study the effects of the metal ion identity and π-cation interactions on the dissociation pathways of metal-bis(peptide) complexes, where the metal is either Mn(2+), Co(2+), Ni(2+), Cu(2+), or Zn(2+); and the peptide is either FGGF, GGGG, GF, or GG, where G is glycine and F is phenylalanine. The [(FGGF)(FGGF-H) + M(2+)](+) and [(GGGG)(GGGG-H) + M(2+)](+) complexes dissociated by losing one FGGF or GGGG, respectively. Relative binding affinities were measured using the crossover points, where the parent and product ions were equal in ion abundance and a normalized-collision energy scale. The results indicate the relative binding affinities for FGGF and GGGG follow the same order with respect to the transition metal ion identity: Cu(2+) < Ni(2+) < Mn(2+) ≈ Zn(2+) < Co(2+), and the π-cation interactions in the FGGF complex have a measureable stabilizing effect. In contrast, the main fragmentation channels of [(GF)(GF-H) + M(2+)]+ and [(GG)(GG-H) + M(2+)](+) are loss of CO(2) and 2CO(2) with the [(GF)(GF-H) + M(2+)](+) complex also exhibiting cinnamic acid ,GF, residual glycine, cinnamate and styrene loss.

  6. Brønsted-Lowry Acid Strength of Metal Hydride and Dihydrogen Complexes.

    Science.gov (United States)

    Morris, Robert H

    2016-08-10

    Transition metal hydride complexes are usually amphoteric, not only acting as hydride donors, but also as Brønsted-Lowry acids. A simple additive ligand acidity constant equation (LAC for short) allows the estimation of the acid dissociation constant Ka(LAC) of diamagnetic transition metal hydride and dihydrogen complexes. It is remarkably successful in systematizing diverse reports of over 450 reactions of acids with metal complexes and bases with metal hydrides and dihydrogen complexes, including catalytic cycles where these reactions are proposed or observed. There are links between pKa(LAC) and pKa(THF), pKa(DCM), pKa(MeCN) for neutral and cationic acids. For the groups from chromium to nickel, tables are provided that order the acidity of metal hydride and dihydrogen complexes from most acidic (pKa(LAC) -18) to least acidic (pKa(LAC) 50). Figures are constructed showing metal acids above the solvent pKa scales and organic acids below to summarize a large amount of information. Acid-base features are analyzed for catalysts from chromium to gold for ionic hydrogenations, bifunctional catalysts for hydrogen oxidation and evolution electrocatalysis, H/D exchange, olefin hydrogenation and isomerization, hydrogenation of ketones, aldehydes, imines, and carbon dioxide, hydrogenases and their model complexes, and palladium catalysts with hydride intermediates.

  7. Metal Fluoride Complexes of Na,K-ATPase

    Science.gov (United States)

    Cornelius, Flemming; Mahmmoud, Yasser A.; Toyoshima, Chikashi

    2011-01-01

    The Na,K-ATPase belongs to the P-type ATPase family of primary active cation pumps. Metal fluorides like magnesium-, beryllium-, and aluminum fluoride act as phosphate analogues and inhibit P-type ATPases by interacting with the phosphorylation site, stabilizing conformations that are analogous to specific phosphoenzyme intermediates. Cardiotonic steroids like ouabain used in the treatment of congestive heart failure and arrhythmias specifically inhibit the Na,K-ATPase, and the detailed structure of the highly conserved binding site has recently been described by the crystal structure of the shark Na,K-ATPase in a state analogous to E2·2K+·Pi with ouabain bound with apparently low affinity (1). In the present work inhibition, and subsequent reactivation by high Na+, after treatment of shark Na,K-ATPase with various metal fluorides are characterized. Half-maximal inhibition of Na,K-ATPase activity by metal fluorides is in the micromolar range. The binding of cardiotonic steroids to the metal fluoride-stabilized enzyme forms was investigated using the fluorescent ouabain derivative 9-anthroyl ouabain and compared with binding to phosphorylated enzyme. The fastest binding was to the Be-fluoride stabilized enzyme suggesting a preformed ouabain binding cavity, in accord with results for Ca-ATPase where Be-fluoride stabilizes the E2-P ground state with an open luminal ion access pathway, which in Na,K-ATPase could be a passage for ouabain. The Be-fluoride stabilized enzyme conformation closely resembles the E2-P ground state according to proteinase K cleavage. Ouabain, but not its aglycone ouabagenin, prevented reactivation of this metal fluoride form by high Na+ demonstrating the pivotal role of the sugar moiety in closing the extracellular cation pathway. PMID:21708939

  8. Distribution of heavy metals and radionuclides in sediments, water, and fish in an area of Great Bear Lake contaminated with mine wastes

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J.W.; Sutherland, D.J.

    1981-01-01

    A study was conducted to measure the concentrations of heavy metals and radionuclides in the sediments and water of Great Bear Lake in Alberta, Canada. The lake is near the operating Echo Bay silver mine and the abandoned Eldorado uranium mine. Additional information on the level of mercury in fish tissues was also collected. Concentrations of mercury, lead, manganese, and nickel in sediments were highest near the tailings deposit, and decreased significantly as the distance from the mine increased. Concentrations of arsenic, cobalt, copper, radium 226, lead 210, and thorium 230 varied inconsistently throughout the study area. Heavy metal and radionuclide levels in water were generally below detectable limits. Mercury levels in the flesh of lake trout averaged 0.03 mg/kg.

  9. Tetra- and octa-[4-(2-hydroxyethyl)phenoxy bearing novel metal-free and zinc(II) phthalocyanines: Synthesis, characterization and investigation of photophysicochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Köksoy, Baybars [Marmara University, Department of Chemistry, 34722 Kadıköy, Istanbul (Turkey); Durmuş, Mahmut [Gebze Technical University, Department of Chemistry, 41400 Gebze, Kocaeli (Turkey); Bulut, Mustafa, E-mail: mbulut@marmara.edu.tr [Marmara University, Department of Chemistry, 34722 Kadıköy, Istanbul (Turkey)

    2015-05-15

    In this study, four novel phthalonitriles (1–4) and their corresponding metal-free (5–8) and zinc(II) phthalocyanine derivatives (9–12) bearing 4-(hydroxyethyl)phenoxy groups were synthesized. These novel compounds were characterized by IR, elemental analyses, {sup 1}H-NMR, UV–vis, and MALDI-TOF spectral data. Furthermore, photophysical (fluorescence quantum yields and lifetimes) and photochemical properties (singlet oxygen generation and photodegradation quantum yields) of these phthalocyanines were investigated in dimethylsulfoxide. The studied zinc(II) phthalocyanines generated highly singlet oxygen which is very important for the photodynamic therapy (PDT) of cancer. The fluorescence quenching behaviour of the newly synthesized phthalocyanine compounds were also investigated using 1,4-benzoquinone. - Highlights: • Octa and tetra 4-(hydroxyethyl)phenoxy substituted metal-free and zinc(II) phthalocyanines. • Study of photophysicochemical properties of eight new phthalocyanines. • Highly singlet oxygen generation for novel zinc(II) phthalocyanine photosensitizers.

  10. Prebiotic coordination chemistry: The potential role of transition-metal complexes in the chemical evolution

    Science.gov (United States)

    Beck, M.

    1979-01-01

    In approaching the extremely involved and complex problem of the origin of life, consideration of the coordination chemistry appeared not only as a possibility but as a necessity. The first model experiments appear to be promising because of prebiotic-type synthesis by means of transition-metal complexes. It is especially significant that in some instances various types of vitally important substances (nucleic bases, amino acids) are formed simultaneously. There is ground to hope that systematic studies in this field will clarify the role of transition-metal complexes in the organizatorial phase of chemical evolution. It is obvious that researchers working in the fields of the chemistry of cyano and carbonyl complexes, and of the catalytic effect of transition-metal complexes are best suited to study these aspects of the attractive and interesting problem of the origin of life.

  11. Design, synthesis, and biological properties of triazole derived compounds and their transition metal complexes.

    Science.gov (United States)

    Chohan, Zahid H; Hanif, Muhammad

    2010-10-01

    Triazole derived Schiff bases and their metal complexes (cobalt(II), copper(II), nickel(II), and zinc(II)) have been prepared and characterized using IR, (1)H and (13)C NMR, mass spectrometry, magnetic susceptibility and conductivity measurements, and CHN analysis data. The structure of L(2), N-[(5-methylthiophen-2-yl)methylidene]-1H-1,2,4-triazol-3-amine, has also been determined by the X-ray diffraction method. All the metal(II) complexes showed octahedral geometry except the copper(II) complexes, which showed distorted octahedral geometry. The triazole ligands and their metal complexes have been screened for their in vitro antibacterial, antifungal, and cytotoxic activity. All the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. It is revealed that all the synthesized complexes showed better activity than the ligands, due to coordination.

  12. Single-molecule synthesis and characterization of metal-ligand complexes by low-temperature STM.

    Science.gov (United States)

    Liljeroth, Peter; Swart, Ingmar; Paavilainen, Sami; Repp, Jascha; Meyer, Gerhard

    2010-07-14

    We present scanning tunneling microscopy (STM)-based single-molecule synthesis of linear metal-ligand complexes starting from individual metal atoms (iron or nickel) and organic molecules (9,10-dicyanoanthracene) deposited on an ultrathin insulating film. We directly visualize the frontier molecular orbitals by STM orbital imaging, from which, in conjunction with detailed density functional theory calculations, the electronic structure of the complexes is inferred. Our studies show how the order of the molecular orbitals and the spin-state of the complex can be engineered through the choice of the metal atom. The high-spin iron complex has a singly occupied delocalized orbital with a large spin-splitting that points to the use of these engineered complexes as modular building blocks in molecular spintronics.

  13. Synthesis of monomeric and polymeric alkali and alkaline earth metal complexes using a phosphinoselenoic amide ligand in metal coordination sphere

    Indian Academy of Sciences (India)

    Jayeeta Bhattacharjee; Ravi K Kottalanka; Harinath Adimulam; Tarun K Panda

    2014-09-01

    We report the monomeric complexes of magnesium and calcium of composition [M(THF){2-Ph2P(Se)N(CMe3)}2] [M= Mg (3), n = 1 andM = Ca (4), n = 2)] and polymeric complexes of potassium and barium of composition [K(THF)2{Ph2P(Se)N(CMe3)}] (2) and [K(THF)Ba{Ph2P(Se)N(CMe3)}3](5) respectively. The potassium complex 2 was readily prepared by the reaction of potassium bis(trimethylsilyl)amide with phosphinoselenoic amide ligand (1) at ambient temperature. The calcium complex 4 was prepared by two synthetic routes: in the first method, commonly known as salt metathesis reaction, the potassium complex 2 was made to react with alkaline earth metal diiodide at room temperature to afford the corresponding calcium complex. The metal bis(trimethylsilyl)amides were made to react with protic ligand 1 in the second method to eliminate the volatile bis(trimethyl)silyl amine. The magnesium complex 3 and barium complex 5 were prepared only through the first method. Solid-state structures of all the new complexes were established by single crystal X-ray diffraction analysis. The smaller ionic radii of Mg2+ (0.72Å) and Ca2+ (0.99Å) ions form the monomeric complex, whereas the larger ions K+ (1.38Å) and Ba2+ (1.35Å) were found to form onedimensional polymeric complexes with monoanionic ligand 1. Compound 2 serves an example of magnesium complex with a Mg-Se direct bond.

  14. Extremely bulky amido first row transition metal(II) halide complexes: potential precursors to low coordinate metal-metal bonded systems.

    Science.gov (United States)

    Hicks, Jamie; Jones, Cameron

    2013-04-01

    Reactions of the extremely bulky potassium amide complexes, [KL'(η(6)-toluene)] or [KL"] (L'/L" = N(Ar*)(SiR3), Ar* = C6H2{C(H)Ph2}2Me-2,6,4; R = Me (L') or Ph (L")), with a series of first row transition metal(II) halides have yielded 10 rare examples of monodentate amido first row transition metal(II) halide complexes, all of which were crystallographically characterized. They encompass the dimeric, square-planar chromium complexes, [{CrL'(THF)(μ-Cl)}2] and [{CrL"(μ-Cl)}2], the latter of which displays intramolecular η(2)-Ph···Cr interactions; the dimeric tetrahedral complexes, [{ML'(THF)(μ-Br)}2] (M = Mn or Fe), [{ML"(THF)(μ-X)}2] (M = Mn, Fe or Co; X = Cl or Br) and [{CoL"(μ-Cl)}2] (which displays intramolecular η(2)-Ph···Co interactions); and the monomeric zinc amides, [L'ZnBr(THF)] (three-coordinate) and [L"ZnBr] (two-coordinate). Solution state magnetic moment determinations on all but one of the paramagnetic compounds show them to be high-spin systems. Throughout, comparisons are made with related bulky terphenyl transition metal(II) halide complexes, and the potential for the use of the prepared complexes as precursors to low-valent transition metal systems is discussed.

  15. Non-precious metal complexes with an anionic PCP pincer architecture.

    Science.gov (United States)

    Murugesan, Sathiyamoorthy; Kirchner, Karl

    2016-01-14

    This perspective article provides an overview of the advancements in the field of non-precious metal complexes featuring anionic PCP pincer ligands with the inclusion of aliphatic systems. It covers research from the beginning in 1976 until late 2015 and provides a summary of key developments in this area, which is, to date, limited to the metals nickel, cobalt, iron, and molybdenum. While the research in nickel PCP complexes is already quite extensive, the chemistry of cobalt, iron, and molybdenum PCP complexes is comparatively sparse. With other non-precious metals such as copper, manganese, chromium or vanadium no PCP complexes are known as yet. In the case of nickel PCP complexes already many catalytic applications such as Suzuki-Miyaura coupling, C-S cross coupling, Kharasch and Michael additions, hydrosilylation of aldehydes and ketones, cyanomethylation of aldehydes, and hydroamination of nitriles were reported. While iron PCP complexes were found to be active catalysts for the hydrosilylation of aldehydes and ketones as well as the dehydrogenation of ammonia-borane, cobalt PCP complexes were not applied to any catalytic reactions. Surprisingly, only one molybdenum PCP complex is reported, which was capable of cleaving dinitrogen to give a nitride complex. This perspective underlines that the combination of cheap and abundant metals such as nickel, cobalt, and iron with PCP pincer ligands may result in the development of novel, versatile, and efficient catalysts for atom-efficient catalytic reactions.

  16. Spectroscopic study of molecular structure, antioxidant activity and biological effects of metal hydroxyflavonol complexes

    Science.gov (United States)

    Samsonowicz, Mariola; Regulska, Ewa

    2017-02-01

    Flavonols with varied hydroxyl substitution can act as strong antioxidants. Thanks to their ability to chelate metals as well as to donate hydrogen atoms they have capacity to scavenge free radicals. Their metal complexes are often more active in comparison with free ligands. They exhibit interesting biological properties, e.g. anticancer, antiphlogistic and antibacterial. The relationship between molecular structure and their biological properties was intensively studied using spectroscopic methods (UV-Vis, IR, Raman, NMR, ESI-MS). The aim of this paper is review on spectroscopic analyses of molecular structure and biological activity of hydroxyflavonol metal complexes.

  17. Direct measurement and modulation of single-molecule coordinative bonding forces in a transition metal complex

    DEFF Research Database (Denmark)

    Hao, Xian; Zhu, Nan; Gschneidtner, Tina

    2013-01-01

    Coordination chemistry has been a consistently active branch of chemistry since Werner's seminal theory of coordination compounds inaugurated in 1893, with the central focus on transition metal complexes. However, control and measurement of metal-ligand interactions at the single-molecule level...... remain a daunting challenge. Here we demonstrate an interdisciplinary and systematic approach that enables measurement and modulation of the coordinative bonding forces in a transition metal complex. Terpyridine is derived with a thiol linker, facilitating covalent attachment of this ligand on both gold...

  18. Chemistry of Platinum and Palladium Metal Complexes in Homogeneous and Heterogeneous Catalysis: A Mini Review

    Directory of Open Access Journals (Sweden)

    Mehrban Ashiq

    2013-04-01

    Full Text Available Transition metal complexes of platinum and palladium are most widely used in catalysis. Many synthetic reactions have been carried out with such complexes (used as a catalyst which have specifically polymer ligands, through hydrosilylation, acetoxylation, hydrogenation, hydro-formylation, oligo-merisation and polymerization. Almost many platinum and palladium catalysts are heterogeneous in nature i.e. the reaction taking place on a solid surface. Now from few years homogeneous catalysts which are completely soluble in the liquid phase reactant, has acknowledged too much attention, yet having small industrial applications, mainly due to the striving of platinum and palladium complexes separation from the catalytic products. More recently a transitional type of platinum and palladium catalysts have been synthesized through attachment of the activated transition metal complexes on the surface of polymer support particularly insoluble which has been establish to offer encouraging new collection of catalysts for effective research on synthesis. Many of such complexes will be based on the palladium and platinum metals group. The major objective of this review is to inaugurate the relationship among the reactivity’s of homogeneous platinum and palladium complexes and heterogeneous complexes of these metals (those bonded to the surface of metals.

  19. SYNTHESES, CHARACTERIZATION AND ETHYLENE POLYMERIZATION OF HALF-SANDWICH GROUP IV METAL COMPLEXES WITH TRIDENTATE [O,N,S] LIGANDS

    Institute of Scientific and Technical Information of China (English)

    Ya-lin Qiao; Ping Hu; Guo-xin Jin

    2013-01-01

    A series of half-sandwich group Ⅳ metal complexes with tridentate monoanionic phenoxy-imine arylsulfide[O-NS] ligand [2-But4-Me-6-((2-(SC6H5)C6H4N =CHC6H2O)]-(La) and dianionic phenoxy-amine arylsulfide [O-N-S]ligand [2-Bu'4-Me-6-((2-(SC6H5)C6H4N-CH2C6H2O)]2-(Lb) have been synthesized and characterized.Lb was obtained easily in high yield by reduction of ligand La with excess LiAlH4 in cool diethyl ether.Half-sandwich Group Ⅳ metal complexes CpTi[O-NS]C12 (1a),CpZr[O-NS]C12 (1b),CpTi[O-N-S]C1 (2a),CpZr[O-N-S]C1 (2b) and Cp*Zr[O-N-S]Cl (2c)were synthesized by the reactions of La and Lb with CpTiCl3,CpZrCl3 and Cp*ZrCl3,and characterized by IR,1H-NMR,13C-NMR and elemental analysis.In addition,an X-ray structure analysis was performed on ligand Lb.The title Group Ⅳ half-sandwich bearing tridentate [O,N,S] ligands show good catalytic activities for ethylene polymerization in the presence of methylaluminoxane (MAO) as co-catalyst up to 1.58 × 107 g-PE·mol-Zr-1·h-1.The good catalytic activities can be maintained even at high temperatures such as 100 ℃ exhibiting the excellent thermal stability for these half-sandwich metal pre-catalysts.

  20. Blue-emitting platinum(II) complexes bearing both pyridylpyrazolate chelate and bridging pyrazolate ligands: synthesis, structures, and photophysical properties.

    Science.gov (United States)

    Chang, Sheng-Yuan; Chen, Jing-Lin; Chi, Yun; Cheng, Yi-Ming; Lee, Gene-Hsiang; Jiang, Chang-Ming; Chou, Pi-Tai

    2007-12-24

    A new Pt(II) dichloride complex [Pt(fppzH)Cl2] (1), in which fppzH = 3-(trifluoromethyl)-5-(2-pyridyl)pyrazole, was prepared by the treatment of a pyridylpyrazole chelate fppzH with K2PtCl4 in aqueous HCl solution. Complex 1 could further react with its parent pyrazole (pzH), 3,5-dimethylpyrazole (dmpzH), or 3,5-di-tert-butylpyrazole (dbpzH) to afford the monometallic [Pt(fppz)(pzH)Cl] (2), [Pt(fppz)(dmpzH)Cl] (3), [Pt(fppz)(dmpzH)2]Cl (4), or two structural isomers with formula [Pt(fppz)(dbpzH)Cl] (5a,b). Single-crystal X-ray diffraction studies of 2, 4, and 5a,b revealed a square planar Pt(II) framework, among which a strong interligand hydrogen bonding occurred between fppz and pzH ligands in 2. This interligand H-bonding is replaced by dual N-H...Cl interaction in 4 and both intermolecular N-H...O (with THF solvate) and N-H...Cl interaction in 5a,b, respectively; the latter are attributed to the bulky tert-butyl substituents that force the dbpzH ligand to adopt the perpendicular arrangement. Furthermore, complex 2 underwent rapid deprotonation in basic media to afford two isomeric complexes with formula [Pt(fppz)(mu-pz)]2 (6a,b), which are related to each other according to the spatial orientation of the fppz chelates, i.e., trans- and cis-isomerism. Similar reaction exerted on 3 afforded isomers 7a,b. Both 6a,b (7a,b) are essentially nonemissive in room-temperature fluid state but afford strong blue phosphorescence in solid state prepared via either vacuum-deposited thin film or 77 K CH2Cl2 matrix. As also supported by the computational approaches, the nature of emission has been assigned to be ligand-centered triplet pipi* mixed with certain metal-to-ligand charge-transfer character.

  1. Complexes of 3.6 kDa Maltodextrin with Some Metals

    OpenAIRE

    Schilling, Christopher H.; Anderegg, James W.; Piotr Tomasik

    2004-01-01

    Preparation of magnesium, lanthanum, and bismuth(III) complexes of 3.6 kDa maltodextrin and some properties of the resulting materials are presented. The metal derivatives contain metals bound to the oxygen atoms of the hydroxyl groups of maltodextrin. Additionally, the metal atoms are coordinated to the hydroxyl groups of the D-glucose units of the macroligand. Such coordination stabilized the metal – oxygen bond against hydrolysis, even in boiling water. The presence of magnesium and l...

  2. Complexes of 3.6 kDa Maltodextrin with Some Metals

    Directory of Open Access Journals (Sweden)

    Christopher H. Schilling

    2004-06-01

    Full Text Available Preparation of magnesium, lanthanum, and bismuth(III complexes of 3.6 kDa maltodextrin and some properties of the resulting materials are presented. The metal derivatives contain metals bound to the oxygen atoms of the hydroxyl groups of maltodextrin. Additionally, the metal atoms are coordinated to the hydroxyl groups of the D-glucose units of the macroligand. Such coordination stabilized the metal – oxygen bond against hydrolysis, even in boiling water. The presence of magnesium and lanthanum atoms increased the thermal stability of maltodextrin, whereas bismuth atoms decreased it.

  3. Reactivities of d~0 transition metal complexes toward oxygen:Synthetic and mechanistic studies

    Institute of Scientific and Technical Information of China (English)

    CHEN ShuJian; ZHANG XinHao; LIN ZhenYang; WU YunDong; XUE ZiLing

    2009-01-01

    Transition metals such as Fe in porphyrin complexes are known to bind or react with O_2,and such reactions are critical to many biological functions and catalytic oxidation using O_2.The transition metals in these reactions often contain valence d electrons,and oxidation of metals is an important step.In recent years,reactions of O_2 with d~0 transition metal complexes such as Hf(NR_2)_4 (R=alkyl) have been used to make metal oxide thin films as insulating gate materials in new microelectronic devices.This feature article discusses our recent studies of such reactions and the formation of TiO_2 thin films.In contrast to the reactions of many d~n complexes where metals are often oxidized,reactions of d~0 complexes such as Hf(Nme_2)_4 and Ta(Nme_2)_4(SiR_3) with O_2 usually lead to the oxidation of ligands,forming,e.g.,-ONMe_2 and-OSiR_3 from-Nme_2 and-SiR_3 ligands,respectively.Mechanistic and theoretical studies of these reactions have revealed pathways in the formation of the metal oxide thin films as microelectronic materials.

  4. Reactivities of d~0 transition metal complexes toward oxygen:Synthetic and mechanistic studies

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Transition metals such as Fe in porphyrin complexes are known to bind or react with O2,and such reactions are critical to many biological functions and catalytic oxidation using O2.The transition metals in these reactions often contain valence d electrons,and oxidation of metals is an important step.In recent years,reactions of O2 with d0 transition metal complexes such as Hf(NR2)4(R=alkyl) have been used to make metal oxide thin films as insulating gate materials in new microelectronic devices.This feature article discusses our recent studies of such reactions and the formation of TiO2 thin films.In contrast to the reactions of many dn complexes where metals are often oxidized,reactions of d0 complexes such as Hf(NMe2)4 and Ta(NMe2)4(SiR3) with O2 usually lead to the oxidation of ligands,forming,e.g.,-ONMe2 and -OSiR3 from-NMe2 and-SiR3 ligands,respectively.Mechanistic and theoretical studies of these reactions have revealed pathways in the formation of the metal oxide thin films as microelectronic materials.

  5. Catalytic Activity of Dual Metal Cyanide Complex in Multi-component Coupling Reactions

    Institute of Scientific and Technical Information of China (English)

    Anaswara RAVINDRAN; Rajendra SRIVASTAVA

    2011-01-01

    Several dual metal cyanide catalysts were prepared from potassium ferrocyanide,metal chloride (where metal =Zn2+,Mn2+,Ni2+,Co2+ and Fe2+),t-butanol (complexing agent) and PEG-4000 (co-complexing agent).The catalysts were characterized by elemental analysis (CHN and X-ray fluorescence),X-ray diffraction,N2 adsorption-desorption,scanning electron microscopy,Fourier-transform infiared spectroscopy,and UV-Visible spectroscopy.The dual metal cyanide catalysts were used in several acid catalyzed multi-component coupling reactions for the synthesis of pharmaceutically important organic derivatives.In all these reactions,the Fe-Fe containing dual metal cyanide catalyst was the best catalyst.The catalysts can be recycled without loss in catalytic activity.The advantage of this method is the use of mild,efficient and reusable catalysts for various reactions,which makes them candidates for commercial use.

  6. Synthesis, Structure and Characterization of a Series of Transition Metal Complexes with Tripodal Polyimidazole Ligand

    Institute of Scientific and Technical Information of China (English)

    任颜卫; 吴爱芝; 李珺; 张逢星; 张金花

    2005-01-01

    Five new metal transition metal complexes formed with tripodal polyimidazole ligand tri{2-[2-(1-methyl)imidazoly](methylimino)ethyl}amine ((min)3tren), [Zn(min)3tren](ClO4)2 (1) [Cu(min)3tren](ClO4)2 (2), [Ni(min)3tren]-(ClO4)2 (3), [Co(min)3tren](ClO4)2 (4), and [Mn(min)3tren](ClO4)2·CH3CN (5) were synthesized and characterized by elemental analysis, molar conductances, IR and electronic spectra. Analytical results show 1 : 1 metal-ligand stoichiometry and 2 : 1 type of electrolyte in all metal complexes. The crystal structures of 4 and 5 have been determined. The metal atoms in 4 and 5, being in distorted [MN6] octahedra, are coordinated with three imine nitrogen atoms and three imidazole nitrogen atoms.

  7. A simple access to transition metal cyclopropenylidene complexes

    OpenAIRE

    Bidal, Yannick Daniel; Lesieur, Mathieu; Melaimi, Mohand; Cordes, David Bradford; Slawin, Alexandra Martha Zoya; Bertrand, Guy; Cazin, Catherine S. J.

    2015-01-01

    The authors gratefully acknowledge the Royal Society (University Research Fellowship to CSJC) and the DOE (DE-FG02-13ER16370) for financial support. We report the first example of BAC–Cu complex (BAC = bis(diisopropylamino)cyclopropenylidene) and its use as a carbene-transfer reagent, allowing access to Au–, Pd–, Ir– and Rh–BAC compounds. Catalytic experiments show the high activity of the [CuCl(BAC)] complex in Click chemistry. Postprint Peer reviewed

  8. Correlation between oxygen adsorption energy and electronic structure of transition metal macrocyclic complexes.

    Science.gov (United States)

    Liu, Kexi; Lei, Yinkai; Wang, Guofeng

    2013-11-28

    Oxygen adsorption energy is directly relevant to the catalytic activity of electrocatalysts for oxygen reduction reaction (ORR). In this study, we established the correlation between the O2 adsorption energy and the electronic structure of transition metal macrocyclic complexes which exhibit activity for ORR. To this end, we have predicted the molecular and electronic structures of a series of transition metal macrocyclic complexes with planar N4 chelation, as well as the molecular and electronic structures for the O2 adsorption on these macrocyclic molecules, using the density functional theory calculation method. We found that the calculated adsorption energy of O2 on the transition metal macrocyclic complexes was linearly related to the average position (relative to the lowest unoccupied molecular orbital of the macrocyclic complexes) of the non-bonding d orbitals (d(z(2)), d(xy), d(xz), and d(yz)) which belong to the central transition metal atom. Importantly, our results suggest that varying the energy level of the non-bonding d orbitals through changing the central transition metal atom and/or peripheral ligand groups could be an effective way to tuning their O2 adsorption energy for enhancing the ORR activity of transition metal macrocyclic complex catalysts.

  9. Distribution of heavy metals and radionuclides in sediments, water, and fish in an area of Great Bear Lake contaminated with mine wastes.

    Science.gov (United States)

    Moore, J W; Sutherland, D J

    1981-01-01

    The concentrations of heavy metals and radionuclides in the sediments and water of Great Bear Lake were determined during 1978 near an operating silver mine and an abandoned uranium mine. Additional information on the level of mercury in fish tissues were also collected. The mines, situated on the same site, deposited tailings and other waste material directly into the lake. The concentrations of mercury, lead, manganese, and nickel in the sediments were highest near the tailings deposit and decreased significantly as the distance from the mine increased. Although there were also significant positive correlations between these metals and the organic content of the sediments, water depth and slope of the bottom had no impact on metal distribution. Since the concentrations of arsenic, cobalt, copper, 226radium, 210lead and 230thorium varied inconsistently throughout the study area, the distribution of these substances could not be related to any of the environmental factors that were measured. There were, however, significant negative correlations between the concentrations of 232thorium and 228thorium and distance from the mine and organic content of the sediments. Heavy metal and radionuclide levels in water were generally below detectable limits, reflecting the strong chemical bonding characteristics of the sediments. The low concentrations of mercury in the tissues of lake trout Salvelinus namaycush were probably related to low uptake rates and the ability of this species to move into uncontaminated areas of the lake.

  10. Distribution of heavy metals and radionuclides in sediments, water, and fish in an area of Great Bear Lake contaminated with mine wastes

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J.W.; Sutherland, D.J.

    1981-01-01

    The concentrations of heavy metals and radionuclides in the sediments and water of Great Bear Lake were determined during 1978 near an operating silver mine and an abandoned uranium mine. Additional information on the level of mercury in fish tissues were also collected. The mines, situated on the same site, deposited tailings and other waste material directly into the lake. The concentrations of mercury, lead, manganese, and nickel in the sediments were highest near the tailings deposit and decreased significantly as the distance from the mine increased. Although there were also significant positive correlations between these metals and the organic content of the sediments, water depth and slope of the bottom had no impact on metal distribution. Since the concentrations of arsenic, cobalt, copper, 226radium, 210lead and 230thorium varied inconsistently throughout the study area, the distribution of these substances could not be related to any of the environmental factors that were measured. There were, however, significant negative correlations between the concentrations of 232thorium and 228thorium and distance from the mine and organic content of the sediments. Heavy metal and radionuclide levels in water were generally below detectable limits, reflecting the strong chemical bonding characteristics of the sediments. The low concentrations of mercury in the tissues of lake trout Salvelinus namaycush were probably related to low uptake rates and the ability of this species to move into uncontaminated areas of the lake.

  11. Cobalt(I) Olefin Complexes: Precursors for Metal-Organic Chemical Vapor Deposition of High Purity Cobalt Metal Thin Films.

    Science.gov (United States)

    Hamilton, Jeff A; Pugh, Thomas; Johnson, Andrew L; Kingsley, Andrew J; Richards, Stephen P

    2016-07-18

    We report the synthesis and characterization of a family of organometallic cobalt(I) metal precursors based around cyclopentadienyl and diene ligands. The molecular structures of the complexes cyclopentadienyl-cobalt(I) diolefin complexes are described, as determined by single-crystal X-ray diffraction analysis. Thermogravimetric analysis and thermal stability studies of the complexes highlighted the isoprene, dimethyl butadiene, and cyclohexadiene derivatives [(C5H5)Co(η(4)-CH2CHC(Me)CH2)] (1), [(C5H5)Co(η(4)-CH2C(Me)C(Me)CH2)] (2), and [(C5H5)Co(η(4)-C6H8)] (4) as possible cobalt metal organic chemical vapor deposition (MOCVD) precursors. Atmospheric pressure MOCVD was employed using precursor 1, to synthesize thin films of metallic cobalt on silicon substrates under an atmosphere (760 torr) of hydrogen (H2). Analysis of the thin films deposited at substrate temperatures of 325, 350, 375, and 400 °C, respectively, by scanning electron microscopy and atomic force microscopy reveal temperature-dependent growth features. Films grown at these temperatures are continuous, pinhole-free, and can be seen to be composed of hexagonal particles clearly visible in the electron micrograph. Powder X-ray diffraction and X-ray photoelectron spectroscopy all show the films to be highly crystalline, high-purity metallic cobalt. Raman spectroscopy was unable to detect the presence of cobalt silicides at the substrate/thin film interface.

  12. Synthesis, Crystal Structure and Luminescent Property of a Novel Pt(II) Complex with Weak Metal-metal Interaction

    Institute of Scientific and Technical Information of China (English)

    YUE Cheng-Yang; JIANG Fei-Long; FENG Rui; HONG Mao-Chun

    2008-01-01

    The title complex cis-bis(tetrahydrothiophene)-bis(nitrate) platinum(II), (tht)2Pt(NO3)2, was the reducing product from potassium hexachloroplatinate(IV) K2PtCl6 where the platinum is tetra-valenced. Crystal data for C8H16N2O6PtS2: monoclinic, space group P21/c, a = 9.8833(5), b = 8.6744(4), c = 18.6407(9) (A), β = 114.401(3)°, V = 1455.35(12) (A)3, Z = 4, Mr = 495.44, Dc = 2.261 g/cm3, F(000) = 944, μ = 9.950 mm-1, λ(MoKα) = 0.71073 (A), T = 293(2) K, 2θmax = 54.96o, GOOF = 1.033, R = 0.0350 and wR = 0.0785 for 2572 observed reflections with I > 2σ(I). X-ray diffraction studies reveal that the title complex has interesting weak metal-metal interactions and two molecules linked by metal-metal interaction exist as a group. Luminescent spectrum illuminates red emission of the complex at room temperature.

  13. FIRST-ROW TRANSITION METAL COMPLEXES OF OMEPRAZOLE AS ANTI-ULCERATIVE DRUGS

    Directory of Open Access Journals (Sweden)

    Suman Malik

    2010-12-01

    Full Text Available Omeprazole (OME is a proton pump inhibitor (PPI. PPIs have enabled to improve the treatment of various acid-peptic disorders. OME is a weak base and it can form several complexes with transition and non-transition metal ions. In the present paper, we are describing series of transition metal complexes of omeprazole i.e., 5-methoxy-2[(4methoxy-3, 5dimethyl-2-pyridinyl methylsulfinyl]-1H-benzimidazole with CuII, MnII, CoII, NiII, FeII, ZnII and HgII. These complexes were characterized by elemental analysis, molar conductivity, IR, NMR, magnetic susceptibility, UV-visible spectral studies, ESR, SEM and X-ray diffraction. Based on the above studies, the ligand behaves as bidentate O, N donor and forms coordinate bonds through C=N and S=O groups. The complexes were found to non-electrolytic in nature on the basis of low values of molar conductivity. Analytical data and stoichiometry analysis suggest ligand to metal ratio of 2:1 for all the complexes. Electronic spectra and magnetic susceptibility measurements reveal octahedral geometry for Mn(II,Co(II, Ni(II,Fe(II and Cu(II complexes and tetrahedral for Hg(II and Zn(II complexes. Ligands and their metal complexes have been screened for their antibacterial and antifungal activities against bacteria Pseudomonas, Staphylococcus aureus and fungi Aspergillus niger and A. flavous.

  14. Engineering and Sizing Nanoreactors To Confine Metal Complexes for Enhanced Catalytic Performance

    NARCIS (Netherlands)

    Shakeri, Mozaffar; Roiban, Lucian; Yazerski, Vital; Prieto Gonzalez, Gonzalo; Klein Gebbink, Bert; de Jongh, Petra E.; de Jong, Krijn P.

    2014-01-01

    Homogeneous metal complexes often display superior activity and selectivity in catalysis of chemical transformations. Heterogenization of these complexes by immobilization on solid supports has been used to facilitate recovery, but this is often associated with a decrease in catalytic performance. W

  15. Raman scattering and photophysics in spin-state-labile d(6) metal complexes

    NARCIS (Netherlands)

    Browne, WR; McGarvey, JJ

    2006-01-01

    In this review two areas of d(6) transition metal ion chemistry and photophysics are briefly reviewed (i) that of Ru(II)dipyridophenazine (dppz) complexes as DNA intercalators and (ii) spin crossover behavior in Fe(II) complexes. In both areas the role of Raman spectroscopy in providing information

  16. Gallium(III) and indium(III) dithiolate complexes: Versatile precursors for metal sulfides

    Indian Academy of Sciences (India)

    Shamik Ghoshal; Vimal K Jain

    2007-11-01

    The chemistry of classical and organometallic complexes of gallium and indium with dithiolate ligands, i.e., dithiocarboxylates, xanthates, dithiocarbamates, dithiophosphates, dithiophophinates and dithioarsenates, has been reviewed. Synthesis, spectroscopic and structural aspects of these complexes are described. Their emerging role as single source molecular precursors for the preparation of metal sulfide thin films and nano-particles has been discussed.

  17. Synthesis, spectral characterization of Schiff base transition metal complexes: DNA cleavage and antimicrobial activity studies

    Indian Academy of Sciences (India)

    N Raman; J Dhaveethu Raja; A Sakthivel

    2007-07-01

    A new series of transition metal complexes of Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) have been synthesized from the Schiff base (L) derived from 4-aminoantipyrine, 3-hydroxy-4-nitrobenzaldehyde and -phenylenediamine. Structural features were obtained from their elemental analyses, magnetic susceptibility, molar conductance, mass, IR, UV-Vis, 1H NMR and ESR spectral studies. The data show that these complexes have composition of ML type. The UV-Vis, magnetic susceptibility and ESR spectral data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The redox behaviour of copper and vanadyl complexes was studied by cyclic voltammetry. Antimicrobial screening tests gave good results in the presence of metal ion in the ligand system. The nuclease activity of the above metal complexes shows that Cu, Ni and Co complexes cleave DNA through redox chemistry whereas other complexes are not effective.

  18. Cations in a Molecular Funnel: Vibrational Spectroscopy of Isolated Cyclodextrin Complexes with Alkali Metals

    NARCIS (Netherlands)

    Gamez, F.; Hurtado, P.; Hortal, A. R.; Martinez-Haya, B.; G. Berden,; Oomens, J.

    2013-01-01

    The benchmark inclusion complexes formed by -cyclodextrin (CD) with alkali-metal cations are investigated under isolated conditions in the gas phase. The relative CD-M+ (M=Li+, Na+, K+, Cs+) binding affinities and the structure of the complexes are determined from a combination of mass spectrometry,

  19. System with potential dual modes of metal-ligand cooperation: highly catalytically active pyridine-based PNNH-Ru pincer complexes.

    Science.gov (United States)

    Fogler, Eran; Garg, Jai Anand; Hu, Peng; Leitus, Gregory; Shimon, Linda J W; Milstein, David

    2014-11-24

    Metal-ligand cooperation (MLC) plays an important role in catalysis. Systems reported so far are generally based on a single mode of MLC. We report here a system with potential for MLC by both amine-amide and aromatization-dearomatization ligand transformations, based on a new class of phosphino-pyridyl ruthenium pincer complexes, bearing sec-amine coordination. These pincer complexes are effective catalysts under unprecedented mild conditions for acceptorless dehydrogenative coupling of alcohols to esters at 35 °C and hydrogenation of esters at room temperature and 5 atm H2. The likely actual catalyst, a novel, crystallographically characterized monoanionic de-aromatized enamido-Ru(II) complex, was obtained by deprotonation of both the N-H and the methylene proton of the N-arm of the pincer ligand. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Preparation, structural characterization and biological evaluation of L-tyrosinate metal ion complexes

    Science.gov (United States)

    Refat, Moamen S.; El-Korashy, Sabry A.; Ahmed, Ahmed S.

    2008-06-01

    The complexes formed between different metal ions and biological molecules like amino acids play an important role in human life. Sn(II), Sn(IV), Zn(II), Cd(II), Hg(II), Cr(III), Fe(III), La(III), ZrO(II) and UO 2(II) complexes are synthesized with L-tyrosine (tyr). These complexes are characterized by elemental analysis, molar conductance, magnetic measurements, mass, IR, UV-vis and 1H NMR spectra as well as thermogravimetric analysis (TGA/DTG). It has been found from the elemental analysis and the thermal studies that the ligand behaves as bidentate ligand forming chelates with 1:3 (metal:ligand) stoichiometry for trivalent metals and 1:2 for divalent and tetravalent metals. The molar conductance measurements of the complexes in DMSO indicate that the complexes are non-electrolyte. The activation energies and other kinetic parameters were calculated from the Coats-Redfern and Horowitz-Metzger equations. The biological activities of the metal complexes have also been studied against different bacteria and fungi.

  1. Influence of Humic Acid Complexation with Metal Ions on Extracellular Electron Transfer Activity.

    Science.gov (United States)

    Zhou, Shungui; Chen, Shanshan; Yuan, Yong; Lu, Qin

    2015-11-23

    Humic acids (HAs) can act as electron shuttles and mediate biogeochemical cycles, thereby influencing the transformation of nutrients and environmental pollutants. HAs commonly complex with metals in the environment, but few studies have focused on how these metals affect the roles of HAs in extracellular electron transfer (EET). In this study, HA-metal (HA-M) complexes (HA-Fe, HA-Cu, and HA-Al) were prepared and characterized. The electron shuttle capacities of HA-M complexes were experimentally evaluated through microbial Fe(III) reduction, biocurrent generation, and microbial azoreduction. The results show that the electron shuttle capacities of HAs were enhanced after complexation with Fe but were weakened when using Cu or Al. Density functional theory calculations were performed to explore the structural geometry of the HA-M complexes and revealed the best binding sites of the HAs to metals and the varied charge transfer rate constants (k). The EET activity of the HA-M complexes were in the order HA-Fe > HA-Cu > HA-Al. These findings have important implications for biogeochemical redox processes given the ubiquitous nature of both HAs and various metals in the environment.

  2. Bivalent transition metal complexes of cetirizine: Spectroscopic, equilibrium studies and biological activity

    Science.gov (United States)

    El-Sherif, Ahmed A.; Shoukry, Mohamed M.; Abobakr, Lamis O.

    2013-08-01

    Metal complexes of cetirizineṡ2HCl (CTZ = 2-[2-[4-[(4-chlorophenyl)phenyl methyl]piperazine-1-yl]-ethoxy]acetic acid, dihydrochloride have been prepared and characterized by elemental analyses, IR, solid reflectance, magnetic moment, molar conductance, and UV-Vis spectra. The analytical data of the complexes show the formation of 1:2 [M:L] ratio, where M represents Ni(II), Co(II) and Cu(II) ions, while L represents the deprotonated CTZ ligand. IR spectra show that CTZ is coordinated to the metal ions in a monodentate manner through carboxylate-O atom. Protonation equilibria of CTZ and its metal complexation by some divalent metal ions were determined in aqueous solution at constant ionic strength (0.1 M NaCl) using an automatic potentiometric technique. Thermodynamic parameters for the protonation equilibria of CTZ were calculated and discussed. The stability order of M(II)-CTZ complexes were found to obey Mn2+ Bacillus subtillis RCMB 010067, Staphylococcus aureus RCMB 010028, Pseudomonas aeuroginosa RCMB 010043, and Escherichia coli RCMB 010052) and fungi as (Aspergillus flavus RCMB 02568, Pencicillium italicum RCMB 03924, Candida albicans RCMB 05031 and Geotricum candidum RCMB 05097). The activity data show that the metal complexes have antibacterial and antifungal activity more than the parent CTZ ligand against one or more bacterial or fungi species. MIC was evaluated for the isolated complexes.

  3. Alkali-crown ether complexes at metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Thontasen, Nicha; Deng, Zhitao; Rauschenbach, Stephan [Max Planck Institute for Solid State Research, Stuttgart (Germany); Levita, Giacomo [University of Trieste, Trieste (Italy); Malinowski, Nikola [Max Planck Institute for Solid State Research, Stuttgart (Germany); Bulgarian Academy of Sciences, Sofia (Bulgaria); Kern, Klaus [Max Planck Institute for Solid State Research, Stuttgart (Germany); EPFL, Lausanne (Switzerland)

    2010-07-01

    Crown ethers are polycyclic ethers which, in solution, selectively bind cations depending on the size of the ring cavity. The study of a single host-guest complex is highly desirable in order to reveal the characteristics of these specific interactions at the atomic scale. Such detailed investigation is possible at the surface where high resolution imaging tools like scanning tunneling microscopy (STM) can be applied. Here, electrospray ion beam deposition (ES-IBD) is employed for the deposition of Dibenzo-24-crown-8 (DB24C8)-H{sup +}, -Na{sup +} and -Cs{sup +} complexes on a solid surface in ultrahigh vacuum (UHV). Where other deposition techniques have not been successful, this deposition technique combines the advantages of solution based preparation of the complex ions with a highly clean and controlled deposition in UHV. Single molecular structures and the cation-binding of DB24C8 at the surface are studied in situ by STM and MALDI-MS (matrix assisted laser desorption ionization mass spectrometry). The internal structure of the complex, i.e. ring and cavity, is observable only when alkali cations are incorporated. The BD24C8-H{sup +} complex in contrast appears as a compact feature. This result is in good agreement with theoretical models based on density functional theory calculations.

  4. Synthesis and Characterization of Metallic Gel Complexes Derived from Carboxymethyl Cellulose

    Directory of Open Access Journals (Sweden)

    H. D. Juneja

    2013-01-01

    Full Text Available The oxaloyl carboxymethyl cellulose (OCMC complexes of Mn(II, Co(II, Ni(II, Cu(II, and Zn(II metal ions have been synthesized and the coordination of OCMC in these complexes has been investigated through IR spectra, reflectance spectra, and thermal analysis. On the basis of spectral and thermal data an octahedral geometry was assigned to [Mn(IIOCMC(H2O2]n and [Co(IIOCMC(H2O2]n, square planar geometry was assigned to [Cu(IIOCMC]n, and tetrahedral geometry was assigned to [Ni(IIOCMC]n and [Zn(IIOCMC]n Metallic Gel complexes.

  5. Catalytic hydrogenation using complexes of base metals with tridentate ligands

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Kalyan V.; Zhang, Guoqi; Hanson, Susan K.

    2016-09-06

    Complexes of cobalt and nickel with tridentate ligand PNHP.sup.R are effective for hydrogenation of unsaturated compounds. Cobalt complex [(PNHP.sup.Cy)Co(CH.sub.2SiMe.sub.3)]BAr.sup.F.sub.4 (PNHP.sup.Cy=bis[2-(dicyclohexylphosphino)ethyl]amine, BAr.sup.F.sub.4=B(3,5-(CF.sub.3).sub.2C.sub.6H.sub.3).sub.4)) was prepared and used with hydrogen for hydrogenation of alkenes, aldehydes, ketones, and imines under mild conditions (25-60.degree. C., 1-4 atm H.sub.2). Nickel complex [(PNHP.sup.Cy)Ni(H)]BPh.sub.4 was used for hydrogenation of styrene and 1-octene under mild conditions. (PNP.sup.Cy)Ni(H) was used for hydrogenating alkenes.

  6. Catalytic hydrogenation using complexes of base metals with tridentate ligands

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, Susan K.; Zhang, Guoqi; Vasudevan, Kalyan V.

    2017-02-14

    Complexes of cobalt and nickel with tridentate ligand PNHP.sup.R are effective for hydrogenation of unsaturated compounds. Cobalt complex [(PNHP.sup.Cy)Co(CH.sub.2SiMe.sub.3)]BAr.sup.F.sub.4 (PNHP.sup.Cy=bis[2-(dicyclohexylphosphino)ethyl]amine, BAr.sup.F.sub.4=B(3,5-(CF.sub.3).sub.2C.sub.6H.sub.3).sub.4)) was prepared and used with hydrogen for hydrogenation of alkenes, aldehydes, ketones, and imines under mild conditions (25-60.degree. C., 1-4 atm H.sub.2). Nickel complex [(PNHP.sup.Cy)Ni(H)]BPh.sub.4 was used for hydrogenation of styrene and 1-octene under mild conditions. (PNP.sup.Cy)Ni(H) was used for hydrogenating alkenes.

  7. Synthesis and biological studies of 4', 7, 8-trihydroxy-isoflavone metal complexes.

    Science.gov (United States)

    Tang, Li-Jun; Chen, Xiang; Sun, Yu-Na; Ye, Jia; Lu, Jing; Han, Ying; Jiang, Xing; Cheng, Chan-Chan; He, Cheng-Cheng; Qiu, Pei-Hong; Li, Xiao-Kun

    2011-12-01

    A new series of complexes of a ligand 4', 7, 8-trihydroxy-isoflavone with transition metal (zinc, copper, manganese, nickel, cobalt) and selenium have been synthesized and characterized with the aid of elemental analysis, IR, electron ionization mass spectrum (EI-MS) and (1)H NMR spectrometric techniques. The compounds were evaluated for their in vitro antibacterial activities and antitumor properties. The metal complexes were found to be more active than the free ligand. Investigation on the interaction between the complexes and calf-thymus DNA (CT DNA) showed that the absorbance of CT DNA increased and the maximum peak (λ(max)=260 nm) red-shifted, while the intensity of fluorescence spectra of Epstein-Bart DNA (EB-DNA) gradually weakened, which indicated that all of these metal complexes tightly combined with CT DNA.

  8. Synthesis of Chiral Metal Complexes of Unsymmetrical Schiff Bases

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Recently, in asymmetric catalyst research the great developments of chiral Salen complexes have been made, but the report on unsymmetrical schiff bases is deficient. The unsymmetrical schiff bases complexes are an effective system in catalytically selective Olefin-epoxidations1. At the same time, unsymmetrical schiff bases was immobilized onto polymer supports for heterogenization2. The potential benefits of the catalyst include facilitation of catalyst separation from reagents, simplification of methods for catalyst recycle, and the possible adaptation of the immobilized catalyst to continuous-flow processes. A series of new unsymmetrical schiff bases was synthesized to study the relations between unsymmetry and enantioselectivity and select better catalyst. The following is the route:

  9. Synthesis and antibacterial activity of cephradine metal complexes : part II complexes with cobalt, copper, zinc and cadmium.

    Science.gov (United States)

    Sultana, Najma; Arayne, M Saeed; Afzal, M

    2005-01-01

    Cephradine, the first generation cephalosporin, is active against a wide range of Gram-positive and Gram-negative bacteria including penicillinase-producing Staphylococci. Since the presence of complexing ligand may affect the bioavailability of a metal in the blood or tissues, therefore, in order to study the probable interaction of cephradine with essential and trace elements present in human body, cephradine has been reacted with cobalt, copper, zinc and cadmium metal halides in L:M ratio of 2:1 in methanol and the products recrystallized from suitable solvents to pure crystals of consistent melting points. Infrared and ultraviolet studies of these complexes were carried out and compared with ligand. Magnetic susceptibility studies of these complexes were also carried out showing their paramagnetic behavior. From the infra red studies and elemental analysis of the complexes, it has been shown that the drug molecule serves as a bidentate ligand coordinating through both its carboxylate at C-3 and beta-lactam nitrogen and the metal having a square planar or octahedral geometry. To evaluate the changes in microbiological activity of cephradine after complexation, antibacterial studies were carried out by observing the changes in MIC (minimum inhibitory concentration) of the complexes and compared with the parent drug by measuring the zone of inhibition of complexes and compared with the parent cephalosporin against both Gram-positive and Gram-negative organisms. For MIC observation, serial dilution method was employed and zone series were determined by disk diffusion method. Our investigations reveal that formation of complexes results in decrease in antibacterial activity of cephradine and MIC values are increased.

  10. Synthesis, characterization, thermal and antioxidant studies of potassium dihydrobisphenothiazinyl borate and its transition metal complexes.

    Science.gov (United States)

    Nami, Shahab A A; Alam, Mahboob; Husain, Ahmad; Parveen, Mehtab

    2012-10-01

    The bidentate borate anion H(2)B(ptz)(2)(-) and its transition metal complexes have been synthesized and characterized by elemental analyses, magnetic susceptibility, electronic, IR, (1)H and (13)C NMR data. The molar conductance of 10(-3) M solution for all the complexes supports their non-ionic nature. The TGA profile of borate anion shows a single stage unlike that of two stage decomposition plot of the metal complexes. On the basis of spectroscopic studies the geometry of all the complexes have been proposed to be distorted-tetrahedral. The in vitro antioxidant and lipid oxidation inhibition of the ligand and its complexes have also been studied. The Cu[B(ptz)(2)](2) complex was found to be most effective in all the studies.

  11. Synthesis, spectral, thermal and antimicrobial studies of some new tri metallic biologically active ceftriaxone complexes.

    Science.gov (United States)

    Ali, Alaa E

    2011-01-01

    Iron, cobalt, nickel and copper complexes of ceftriaxone were prepared in 1:3 ligand:metal ratio to examine the ligating properties of the different moieties of the drug. The complexes were found to have high percentages of coordinated water molecules. The modes of bonding were discussed depending on the infrared spectral absorption peaks of the different allowed vibrations. The Nujol mull electronic absorption spectra and the magnetic moment values indicated the Oh geometry of the metal ions in the complexes. The ESR spectra of the iron, cobalt, and copper complexes were determined and discussed. The thermal behaviors of the complexes were studied by TG and DTA techniques. The antimicrobial activities of the complexes were examined and compared to that of the ceftriaxone itself.

  12. Some Transition Metal Complexes of NO Type Schiff Base: Preparation and Characterization

    Directory of Open Access Journals (Sweden)

    Erdal CANPOLAT

    2016-04-01

    Full Text Available Metal complexes of Schiff base ligand (5-bromo-3-methoxysalicyliden-p-iminoacetophenone oxime derived from 5-bromo-3-methoxsalicylaldehyde and p-aminoacetophenoneoxime is reported. Schiff base was found to be bidentate ligand involving the imino nitrogen and carboxyl oxygen atoms in the complexes. Metal to ligand ratio were found to be 1:2 for all of the complexes. Co(II, Ni(II, and Zn(II complexes have been found tetrahedral geometry and Cu(II complex has been found four coordinated geometry. The complexes are found to have the formulae [M(L2]. The compounds obtained have been characterized by their elemental analyses, IR, 1H-NMR, 13C-NMR, UV spectra, magnetic susceptibility and thermogravimetric analyses (TGA.

  13. Synthesis, structural characterization and biological studies of some nalidixic acid-metal complexes: Metalloantibiotic complexes of some divalent and trivalent metal ions

    Science.gov (United States)

    Al-Khodir, Fatima A. I.; Refat, Moamen S.

    2015-08-01

    This article describes the synthesis, characterization, computational and biological assessments of some divalent and trivalent metal (Ca(II), Fe(III), Pd(II) and Au(III)) complexes of nalidixic acid (nixH). The structures of these complexes were assigned using elemental analyses and spectral measurements e.g., IR, Raman, 1H NMR, 13C NMR and electronic techniques. These results indicated that, nalidixic acid reacts as a bidentate ligand bound to the metal ion through the oxygen atoms of carbonyl and carboxylate groups. The molar conductance measurements of the complexes in DMSO correspond to be non-electrolyte nature. Thus, these complexes may be formulated as [Ca(nix)(Cl)(H2O)3]. H2O, [Fe(nix)(Cl)2(H2O)2]·3H2O, [Pd(nix)(Cl)(H2O)] and [Au(nix)(Cl)2]. Base on the Coats-Redfern and Horowitz-Metzeger methods, the kinetic thermodynamic parameters (E∗, ΔS∗, ΔH∗ and ΔG∗) of the thermal decomposition reactions have been calculated from thermogravimetric curves of TG and DTG. The nano-scale range of the nalidixic acid complexes have been discussed using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) analyzer. The computational studies for the synthesized complexes have been estimated.

  14. Trace Metal-Humic Complexes in Natural Waters: Insights From Speciation Experiments

    Science.gov (United States)

    Stern, J. C.; Salters, V.; Sonke, J.

    2006-12-01

    The DOM cycle is intimately linked to the cycling and bioavailability of trace metals in aqueous environments. The presence or absence of DOM in the water column can determined whether trace elements will be present in limited quantities as a nutrient, or in surplus quantities as a toxicant. Humic substances (HS), which represent the refractory products of DOM degradation, strongly affect the speciation of trace metals in natural waters. To simulate metal-HS interactions in nature, experiments must be carried out using trace metal concentrations. Sensitive detection systems such as ICP-MS make working with small (nanomolar) concentrations possible. Capillary electrophoresis coupled with ICP-MS (CE-ICP-MS) has recently been identified as a rapid and accurate method to separate metal species and calculate conditional binding constants (log K_c) of metal-humic complexes. CE-ICP-MS was used to measure partitioning of metals between humic substances and a competing ligand (EDTA) and calculate binding constants of rare earth element (REE) and Th, Hf, and Zr-humic complexes at pH 3.5-8 and ionic strength of 0.1. Equilibrium dialysis ligand exchange (EDLE) experiments to validate the CE-ICP-MS method were performed to separate the metal-HS and metal-EDTA species by partitioning due to size exclusion via diffusion through a 1000 Da membrane. CE-ICP-MS experiments were also conducted to compare binding constants of REE with humic substances of various origin, including soil, peat, and aquatic DOM. Results of our experiments show an increase in log K_c with decrease in ionic radius for REE-humic complexes (the lanthanide contraction effect). Conditional binding constants of tetravalent metal-humic complexes were found to be several orders of magnitude higher than REE-humic complexes, indicating that tetravalent metals have a very strong affinity for humic substances. Because thorium is often used as a proxy for the tetravalent actinides, Th-HS binding constants can allow us

  15. Alkali metal cation-hexacyclen complexes: effects of alkali metal cation size on the structure and binding energy.

    Science.gov (United States)

    Austin, C A; Rodgers, M T

    2014-07-24

    Threshold collision-induced dissociation (CID) of alkali metal cation-hexacyclen (ha18C6) complexes, M(+)(ha18C6), with xenon is studied using guided ion beam tandem mass spectrometry techniques. The alkali metal cations examined here include: Na(+), K(+), Rb(+), and Cs(+). In all cases, M(+) is the only product observed, corresponding to endothermic loss of the intact ha18C6 ligand. The cross-section thresholds are analyzed to extract zero and 298 K M(+)-ha18C6 bond dissociation energies (BDEs) after properly accounting for the effects of multiple M(+)(ha18C6)-Xe collisions, the kinetic and internal energy distributions of the M(+)(ha18C6) and Xe reactants, and the lifetimes for dissociation of the activated M(+)(ha18C6) complexes. Ab initio and density functional theory calculations are used to determine the structures of ha18C6 and the M(+)(ha18C6) complexes, provide molecular constants necessary for the thermodynamic analysis of the energy-resolved CID data, and theoretical estimates for the M(+)-ha18C6 BDEs. Calculations using a polarizable continuum model are also performed to examine solvent effects on the binding. In the absence of solvent, the M(+)-ha18C6 BDEs decrease as the size of the alkali metal cation increases, consistent with the noncovalent nature of the binding in these complexes. However, in the presence of solvent, the ha18C6 ligand exhibits selectivity for K(+) over the other alkali metal cations. The M(+)(ha18C6) structures and BDEs are compared to those previously reported for the analogous M(+)(18-crown-6) and M(+)(cyclen) complexes to examine the effects of the nature of the donor atom (N versus O) and the number donor atoms (six vs four) on the nature and strength of binding.

  16. Transition Metal Complex/Polymer Systems as Optical Limiting Materials

    Science.gov (United States)

    2013-05-01

    material has a relatively low viscosity and allows the possibility of exploration of bimolecular reactions of encapsulated chromophores with added...dynamics in the host-guest complex of azidopermethylated cyclodextrin (host) and ademantylamide (guest). A clear induction period indicates that the IR

  17. Coinage metal complexes supported by a "PN(3)P" scaffold.

    Science.gov (United States)

    Rao, Gyandshwar Kumar; Gorelsky, Serge I; Korobkov, Ilia; Richeson, Darrin

    2015-11-28

    A series of monovalent group 11 complexes, [2,6-{Ph2PNMe}2(NC5H3)]CuBr 1, [2,6-{Ph2PNMe}2(NC5H3)]CuOTf 2, [2,6-{Ph2PNMe}2(NC5H3)]AgOTf 3, and [2,6-{Ph2PNMe}2(NC5H3)](AuCl)24, supported by a neutral PN(3)P ligand have been synthesized and characterized by multinuclear NMR and single crystal X-ray diffraction studies. The variation of the coordination properties were analyzed and electronic structure calculations have been carried out to provide insight on the bonding details in these complexes. The Cu(I) complexes displayed an unusual coordination geometry with a tridentate pincer ligand and an overall four coordinate trigonal pyramidal geometry. In contrast the Ag(I) analogue displayed a bidentate κ(2)-P,P' ligation leaving the pyridyl-N atom uncoordinated and yielding a pyramidalized trigonal planar geometry around Ag. The bimetallic Au(I) complex completed the series and displayed a monodentate P-bonded ligand and a linear coordination geometry.

  18. Electrochemical Studies of Eight New Divalent Transition Metal Benzenesulphonate Ternary Complexes with 1,10-Phenanthroline

    Institute of Scientific and Technical Information of China (English)

    LU Yao; GUO Li-ping; MA Jian-fang; YANG Jin; WU Dongmei

    2004-01-01

    The electrochemical properties of eight new divalent transition metal benzenesulphonate complexes with 1,10-phenanthroline in different solvents and supporting electrolytes were investigated by means of cyclic voltammetry(CV). Based on the CV data the influences of various coordination modes on the electrochemical behavior of the complexes were discussed. The diffusion coefficient Dc and rate constant ks of those complexes in DMF systems were estimated according to CV and the results show that these processes were all quasi-reversible.

  19. Metal complex with terpyrindine derivative ligand as highly selective colorimetric sensor for iron(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    Peng Wang; Taka-aki Okamura; Hong-Ping Zhou; Wei-Yin Sun; Yu-Peng Tian

    2013-01-01

    A new metal complex [MnL2](NO3)2.CH3CN (1) was synthesized by reaction of 4'-4-(1,2,4-triazol-1-yl)-phenyl-2,2':6',2"-terpyridine (L) with manganese nitrate.The structure of the complex was determined by X-ray crystallography.The results of UV-vis studies showed that the complex exhibits colorimetric sensing ability for Fe3+,which can be observed by naked eye.

  20. Synthesis, characterization, biological and electrical conductivity studies of some Schiff base metal complexes

    Directory of Open Access Journals (Sweden)

    A. R. Yaul

    2014-05-01

    Full Text Available Metal complexes of VO(IV, Zr(IV, Th(IV and UO2(VI with Schiff base ligands derived from 4-nitrobenzoylhydrazide with 2-hydroxy-5-methylacetophenone (H2L1 or 2-hydroxy-5-chloroacetophenone (H2L2 have been prepared. All the complexes have been characterized on the basis of elemental analyses, magnetic susceptibility measurement, electronic and IR spectra and thermogravimetric analysis. The IR spectral data suggested that the ligands behave as dibasic tridentate moiety towards the central metal ion coordinating through phenolic oxygen, enolic oxygen and azomethine nitrogen atoms. The elemental analyses show a 1:1 metal:ligand stoichiometry for all the complexes except Th(IV which has 1:2 stoichiometry. The thermal analysis evidenced that thermal transformations of complexes are processes according to TG curves including dehydration, thermolysis and oxidative degradation of Schiff base. The final product of decomposition is the most stable metallic oxide. The kinetic analysis of the thermogravimetric data was performed by using the Coats-Redfern method. Solid state electrical conductivity of the complexes has been measured in their compressed pellet form over a 310-413 K temperature range. All the complexes show semiconducting behavior as their conductivity increases with increasing temperature and a function of ionic size. All the complexes along with ligands were also screened for their antibacterial and antifungal activities. DOI: http://dx.doi.org/10.4314/bcse.v28i2.9

  1. Spectral, thermal and in vitro antimicrobial studies of cyclohexylamine- N-dithiocarbamate transition metal complexes

    Science.gov (United States)

    Mamba, Saul M.; Mishra, Ajay K.; Mamba, Bhekie B.; Njobeh, Patrik B.; Dutton, Mike F.; Fosso-Kankeu, Elvis

    2010-10-01

    Transition metal complexes of the type [M(L) 2] and those containing monodentate phosphines of the type [M(L) 2(PPh 3)] {M = Ni, Co, Cu and Zn; L = cyclohexylamine- N-dithiocarbamate; PPh 3 = triphenylphosphine} have been synthesized. The complexes were characterized using IR, UV-vis, NMR spectroscopy, and thermal analysis (TGA). The 1H NMR, 13C NMR and 31P NMR showed the expected signals for the dithiocarbamate and triphenylphosphine moieties. The spectral studies in all compounds revealed that the coordination of metals occurs via the sulphur atom of the dithiocarbamate ligand in a bidentate fashion. Thermal behavior of the complexes showed that the complexes were more stable than their parent ligands. The ligand moiety is lost in the first step and the rest of the organic moiety decomposes in the subsequent steps. Furthermore, the ligand and their metal complexes were screened in vitro for their antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhi, Enterococcus faecalis, Pseudomonas aeruginosa and Bacillus cereus and antifungal activities against Aspergillus flavus, Aspergillus carbonarius, Aspergillus niger and Aspergillus fumigatus. The metal complexes exhibited higher antimicrobial activity than the parent ligands. Generally, the zinc complexes were effective against the growth of bacteria with Zn(L) 2 displaying broad spectrum bacteriocidal activity at concentrations of 50 μg/mL; and Ni(L) 2 was more effective against the growth of fungi at concentrations of 100-400 μg/mL under laboratory conditions.

  2. DNA interactions and biocidal activity of metal complexes of benzothiazole Schiff bases: synthesis, characterization and validation

    Indian Academy of Sciences (India)

    NARENDRULA VAMSIKRISHNA; MARRI PRADEEP KUMAR; GALI RAMESH; NIRMALA GANJI; SREENU DARAVATH; SHIVARAJ

    2017-05-01

    Binary complexes of Cu(II), Ni(II) and Co(II) were synthesized using two novel Schiff bases L₁ = 2-(-(benzothiazol-6-ylimino)methyl)-4-chlorophenol (BTEMCP), L₂= 2-(-(benzothiazol-6-ylimino) methyl)-4-nitrophenol. The Schiff bases and metal complexes were characterized by analytical and spectral methods like elemental analysis, Mass, ¹H-NMR, ¹³ C-NMR, UV-Vis, IR, ESR, SEM, EDX, XRD and magnetic susceptibility measurements. From the analytical data, square planar geometry has been proposed for all themetal complexes. The binding interaction between the metal complexes and DNA was investigated by means of electronic absorption, fluorescence spectroscopy and viscosity measurements. The DNA cleavage ability ofthe metal complexes was also evaluated by agarose gel electrophoresis method. These studies revealed that the complexes showed an intercalative mode of binding to CT DNA and also effectively cleaved the supercoiledpBR DNA. The synthesised compounds were evaluated for in vitro antibacterial activity against Gram positive and Gram negative bacteria, and found that the metal complexes showed more potent biocidal activity than theSchiff bases.

  3. Correlation between ionic radii of metal azodye complexes and electrical conductivity.

    Science.gov (United States)

    El-Ghamaz, N A; El-Sonbati, A Z; Diab, M A; El-Bindary, A A; Mohamed, G G; Morgan, Sh M

    2015-08-01

    5-(2,3-Dimethyl-1-phenylpyrazol-5-one azo)-2-thioxo-4-thiazolidinone (HL) and its metal complexes with copper(II) (1), cobalt(II) (2) and nickel(II) (3) are synthesized and characterized by physico-chemical techniques. The thermal properties of the ligand (HL) and its metal complexes (1-3) are discussed. The thermal activation energies of decomposition (Ea) of HL and its metal complexes with Cu(II), Co(II) and Ni(II) are found to be 48.76, 36.83, 30.59 and 40.45 kJ/mol, respectively. The frequency and temperature dependence of ac conductivity, dielectric constants for HL and its complexes (1-3) are investigated in the temperature range 300-356 K and frequency range 0.1-100 kHz. Both of the ac conductivity and the values of the thermal activation energy for conduction, as well as the dielectric properties of the complexes of HL are found to depend on the nature of the metallic ions. The values of the thermal activation energies of electrical conductivity decrease with increasing the value of test frequency. The small polarons tunneling (SPT) is the dominant conduction mechanism for the ligand (HL), while for complex (2) the overlapping large tunneling model (OLPT) is the dominant conduction mechanism. The correlated barrier hopping (CBH) is the dominant conduction mechanism for both of the complexes (1) and (3).

  4. Microwave Synthesis, Spectral, Thermal and Electrical Properties of Some Metal Complexes Involving 5-Bromosalicylaldehyde

    Directory of Open Access Journals (Sweden)

    Rajendra K. Jain

    2012-01-01

    Full Text Available Microwave-assisted synthesis is a branch of green chemistry. The salient features of microwave approach are shorter reaction times, simple reaction conditions and enhancements in yields. Some new Schiff base complexes of Cr(III, Co(II, Ni(II and Cu(II derived from 5-bromosalicylaldehyde with 4-nitro-1,2-phenylenediamine (H2L1 have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, ESR, magnetic susceptibility and thermal analysis. The complexes exhibit coordination number 4 or 6. The complexes are coloured and stable in air. Analytical data revealed that all the complexes exhibited 1:1 (metal: ligand ratio. FAB-mass and thermal data show degradation pattern of the complexes. The thermal behavior of metal complexes shows that the hydrated complexes loses water molecules of hydration in the first step; followed by decomposition of ligand molecules in the subsequent steps. The solid state electrical conductivity of the metal complexes has also been measured. Solid state electrical conductivity studies reflect semiconducting nature of the complexes.

  5. β-Cyclodextrin as a Metal-anionic Porphyrin Complexation Accelerator in Aqueous Media.

    Science.gov (United States)

    Ohtomo, Takao; Yokoyama, Aya; Konno, Mitsuyuki; Ohno, Osamu; Igarashi, Shukuro; Takagai, Yoshitaka

    2016-01-01

    The rate of the complexation reaction between anionic porphyrins and 11 metal ions was found to be accelerated by the presence of β-cyclodextrin (β-CD) in aqueous media at room temperature without the need for additional heating or sonication. The porphyrin complexation reaction with metal ions under aqueous conditions can be difficult due to the strong hydration energy between the metal ions and water. In this study, the specific role of β-CD as an accelerator was determined and found to enhance the typically slow reaction of the porphyrin with metal ions. A significant acceleration effect was exhibited when the model anionic porphyrin, 5,10,15,20-tetraphenyl-21H,23H-porphine-tetrasulfonic acid, and Pb(II) ions were combined in the presence of β-CD. Other than for Hg ion, the addition of β-CD decreased the metalation reaction time from 30 to 2 min. The order in the degree of acceleration was Pb > Zn, Cd > Cu > Fe, Pd > Sn > Ag, Co, Mn. Using Pb(II) as the model ion, it was determined that the complexation rate constant was enhanced by a factor of 2.4, while the dissociation rate constant was diminished by a factor of 135 in the presence of added β-CD relative to that in its absence. Overall, the complex was much more stable (formation equilibrium constant 324-fold greater in the β-CD medium. The formation of a ternary complex (cf. bicapped complex; (β-CD)2-porphyrin-metal ion) was demonstrated through the use of nuclear magnetic-resonance spectroscopy and mass spectrometry. This acceleration effect is expected to be applicable systems in which porphyrin ligands are employed for determining of metal ions in chemical analysis and separation science.

  6. Spectroscopic characterization of metal complexes of novel Schiff base. Synthesis, thermal and biological activity studies.

    Science.gov (United States)

    Omar, M M; Mohamed, Gehad G; Ibrahim, Amr A

    2009-07-15

    Novel Schiff base (HL) ligand is prepared via condensation of 4-aminoantipyrine and 2-aminobenzoic acid. The ligand is characterized based on elemental analysis, mass, IR and (1)H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance and thermal analyses (TGA, DrTGA and DTA). The molar conductance data reveal that all the metal chelates are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a uninegatively tridentate manner with NNO donor sites of the azomethine N, amino N and deprotonated caroxylic-O. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia Coli, Pseudomonas aeruginosa, Staphylococcus Pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Shciff base ligand against one or more bacterial species.

  7. Metal complexes in cancer therapy – an update from drug design perspective

    Directory of Open Access Journals (Sweden)

    Ndagi U

    2017-03-01

    Full Text Available Umar Ndagi, Ndumiso Mhlongo, Mahmoud E Soliman Molecular Modelling and Drug Design Research Group, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, South Africa Abstract: In the past, metal-based compounds were widely used in the treatment of disease conditions, but the lack of clear distinction between the therapeutic and toxic doses was a major challenge. With the discovery of cisplatin by Barnett Rosenberg in 1960, a milestone in the history of metal-based compounds used in the treatment of cancers was witnessed. This forms the foundation for the modern era of the metal-based anticancer drugs. Platinum drugs, such as cisplatin, carboplatin and oxaliplatin, are the mainstay of the metal-based compounds in the treatment of cancer, but the delay in the therapeutic accomplishment of other metal-based compounds hampered the progress of research in this field. Recently, however, there has been an upsurge of activities relying on the structural information, aimed at improving and developing other forms of metal-based compounds and nonclassical platinum complexes whose mechanism of action is distinct from known drugs such as cisplatin. In line with this, many more metal-based compounds have been synthesized by redesigning the existing chemical structure through ligand substitution or building the entire new compound with enhanced safety and cytotoxic profile. However, because of increased emphasis on the clinical relevance of metal-based complexes, a few of these drugs are currently on clinical trial and many more are awaiting ethical approval to join the trial. In this review, we seek to give an overview of previous reviews on the cytotoxic effect of metal-based complexes while focusing more on newly designed metal-based complexes and their cytotoxic effect on the cancer cell lines, as well as on new approach to metal-based drug design and molecular target in cancer therapy. We are optimistic that the concept of selective

  8. Complex-Morphology Metal-Based Nanostructures: Fabrication, Characterization, and Applications

    Directory of Open Access Journals (Sweden)

    Antonella Gentile

    2016-06-01

    Full Text Available Due to their peculiar qualities, metal-based nanostructures have been extensively used in applications such as catalysis, electronics, photography, and information storage, among others. New applications for metals in areas such as photonics, sensing, imaging, and medicine are also being developed. Significantly, most of these applications require the use of metals in the form of nanostructures with specific controlled properties. The properties of nanoscale metals are determined by a set of physical parameters that include size, shape, composition, and structure. In recent years, many research fields have focused on the synthesis of nanoscale-sized metallic materials with complex shape and composition in order to optimize the optical and electrical response of devices containing metallic nanostructures. The present paper aims to overview the most recent results—in terms of fabrication methodologies, characterization of the physico-chemical properties and applications—of complex-morphology metal-based nanostructures. The paper strongly focuses on the correlation between the complex morphology and the structures’ properties, showing how the morphological complexity (and its nanoscale control can often give access to a wide range of innovative properties exploitable for innovative functional device production. We begin with an overview of the basic concepts on the correlation between structural and optical parameters of nanoscale metallic materials with complex shape and composition, and the possible solutions offered by nanotechnology in a large range of applications (catalysis, electronics, photonics, sensing. The aim is to assess the state of the art, and then show the innovative contributions that can be proposed in this research field. We subsequently report on innovative, versatile and low-cost synthesis techniques, suitable for providing a good control on the size, surface density, composition and geometry of the metallic

  9. Synthesis of Chiral Metal Complexes of Unsymmetrical Schiff Bases

    Institute of Scientific and Technical Information of China (English)

    SONG; Bo

    2001-01-01

    Recently, in asymmetric catalyst research the great developments of chiral Salen complexes have been made, but the report on unsymmetrical schiff bases is deficient. The unsymmetrical schiff bases complexes are an effective system in catalytically selective Olefin-epoxidations1. At the same time, unsymmetrical schiff bases was immobilized onto polymer supports for heterogenization2. The potential benefits of the catalyst include facilitation of catalyst separation from reagents, simplification of methods for catalyst recycle, and the possible adaptation of the immobilized catalyst to continuous-flow processes. A series of new unsymmetrical schiff bases was synthesized to study the relations between unsymmetry and enantioselectivity and select better catalyst. The following is the route:  ……

  10. Low-temperature and damage-free transition metal and magnetic material etching using a new metallic complex reaction

    Science.gov (United States)

    Nozawa, Toshihisa; Miyama, Ryo; Kubota, Shinji; Moyama, Kazuki; Kubota, Tomihiro; Samukawa, Seiji

    2015-03-01

    A neutral beam etching process has been developed that achieves damage- free (chemically and physically) etching. Recently, it was found that transition metals could be etched using neutral beam etching through metallic complex reactions. In this process, a neutral beam is extracted from a plasma generation region into a reaction chamber. Complex reactant gases are injected into a reaction chamber which is screened from the plasma during neutral beam etching. In this paper, etching of Pt and CoFeB, candidate materials for MRAM structures by a neutral beam system is described. It was found that etch rate enhancement of Pt/CoFeB surfaces resulted from their exposure to a neutral beam from Ar/O2 plasma with simultaneous injection of EtOH /acetic acid into the reaction chamber. Etching damage was also evaluated and no magnetic hysteresis degradation has been observed. Neutral beam etching technology has the capability to make breakthrough for fabricating MRAM device.

  11. The first one-pot synthesis of metal-organic frameworks functionalised with two transition-metal complexes.

    Science.gov (United States)

    Platero-Prats, Ana E; Bermejo Gómez, Antonio; Samain, Louise; Zou, Xiaodong; Martín-Matute, Belén

    2015-01-07

    The synthesis of a metal-organic framework (UiO-67) functionalised simultaneously with two different transition metal complexes (Ir and Pd or Rh) through a one-pot procedure is reported for the first time. This has been achieved by an iterative modification of the synthesis parameters combined with characterisation of the resulting materials using different techniques, including X-ray absorption spectroscopy (XAS). The method also allows the first synthesis of UiO-67 with a very wide range of loadings (from 4 to 43 mol %) of an iridium complex ([IrCp*(bpydc)(Cl)Cl](2-) ; bpydc=2,2'-bipyridine-5,5'-dicarboxylate, Cp*=pentamethylcyclopentadienyl) through a pre-functionalisation methodology. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Complexes of metals with humus substances as natural biocolloids: mechanism and size

    Science.gov (United States)

    Dinu, Marina; Shkinev, Valery; Linnik, Vitaly

    2014-05-01

    Metal complexes with humus substances in the soil are natural biocolloids, which are characterized by the size of the nano- to milli grams. Physical state of the compound functional features humus substances (HS), the nature of metal - all these parameters define different mechanisms transportation of the metal in the soil profile. To assess changes in the composition humus substances complexes with metals and molecular weights humus substances used methods ultrotsentrifugation and filtration (ultrafiltration alkali metals do not stay in any of the fractions and to migrate as the ions (40-50 cm). Alkali- earth metals, on the contrary, delayed a layer ( 2-7 cm), most humified layer, explained by the appearance of active d- orbital of the metal cations, and their greater ability to form complexes than alkali metals. Aluminum content of elements of the subgroup represented by several peaks, mainly in the upper layers of the soil in those areas where the most represented type of fulvic humus substances. High concentration of iron in all studied soil layers. An exception is the 15-35 cm layer which contains humic substance in large quantities compared with fulvic acids, that may explain the decrease in the affinity of the metal to the functional groups and less strong sorption communication mechanism. Metal concentrations of nickel and cobalt are practically unchanged with soil depth. Indicating that almost the same ability to bind to humic and fulvic acids. In samples of 5-8 cm identified reduction of zinc and copper ions in the filtrates from 8 microns to 100 kDa. However, complexes with zinc ions of HS molecular weight less than 100 kDa in all filtrates predominates, particularly fulvic type complexes. Lead ions are predominantly high molecular weight complexes of over 1000 kD, so the filtrate was less than 100 kDa lead content is minimal. The content of zinc ion in layers 8-11 sharply decreases with decreasing pore size of the filter is comparable to the reduction

  13. The preparation and use of metal salen complexes derived from cyclobutane diamine

    Science.gov (United States)

    Patil, Smita

    The helix is an important chiral motif in nature, there is increasing development in field of helical transition metal complexes and related supramolecular structures. Hence, the goals of this work are to apply the principles of helicity in order to produce metal complexes with predictable molecular shapes and to study their properties as asymmetric catalysts. Computational studies suggest that the (1R,2 R)-cyclobutyldiamine unit can produce highly twisted salen complexes with a large energy barrier between the M and P helical forms. To test this prediction, the tartrate salt of (1R,2R)-cyclobutyldiamine was synthesized and condensed with a series of saliclaldehydes to produce novel salen ligands. The salicylaldehydes chosen have extended phenanthryl or benz[a]anthryl sidearms to encourage formation of helical coordination complexes. These ligands were metallated with zinc, iron and manganese salts to produce salen metal complexes which were characterized by NMR analysis, high-resolution mass spectrometry, and IR spectroscopy. A second ligand type, neutral bis(pyridine-imine) has also been synthesized from (1R,2R)-cyclobutyldiamine and quinolylaldehydes. The synthesis of bis(pyridine-imine) ligands was conducted using greener method, solvent assisted grinding. These ligands, in-situ with nickel metal salts, showed good catalytic activity for asymmetric Diels-Alder reactions. The third ligand type studied was chiral acid-functionalized Schiff-base ligands. These were synthesized by the condensation of 3-formyl-5-methyl salicylic acid and (1R,2R)-cyclobutyldiamine. With this type of ligand, there is possibility of producing both mono and dinuclear metal complexes. In our studies, we were only able to synthesize mononuclear complexs. These were tested as catalysts for asymmetric direct Mannich-type reaction, but were found to be ineffective.

  14. Estimating the acidity of transition metal hydride and dihydrogen complexes by adding ligand acidity constants.

    Science.gov (United States)

    Morris, Robert H

    2014-02-05

    A simple equation (pKa(THF) = ∑AL + Ccharge + Cnd + Cd6) can be used to obtain an estimate of the pKa of diamagnetic transition metal hydride and dihydrogen complexes in tetrahydrofuran, and, by use of conversion equations, in other solvents. It involves adding acidity constants AL for each of the ligands in the 5-, 6-, 7-, or 8-coordinate conjugate base complex of the hydride or dihydrogen complex along with a correction for the charge (Ccharge = -15, 0 or 30 for x = +1, 0 or -1 charge, respectively) and the periodic row of the transition metal (Cnd = 0 for 3d or 4d metal, 2 for 5d metal) as well as a correction for d(6) octahedral acids (Cd6 = 6 for d(6) metal ion in the acid, 0 for others) that are not dihydrogen complexes. Constants AL are provided for 13 commonly occurring ligand types; of these, nine neutral ligands are correlated with Lever's electrochemical ligand parameters EL. This method gives good estimates of the over 170 literature pKa values that range from less than zero to 50 with a standard deviation of 3 pKa units for complexes of the metals chromium to nickel, molybdenum, ruthenium to palladium, and tungsten to platinum in the periodic table. This approach allows a quick assessment of the acidity of hydride complexes found in nature (e.g., hydrogenases) and in industry (e.g., catalysis and hydrogen energy applications). The pKa values calculated for acids that have bulky or large bite angle chelating ligands deviate the most from this correlation. The method also provides an estimate of the base strength of the deprotonated form of the complex.

  15. Dialkyldiselenophosphinato-metal complexes - a new class of single source precursors for deposition of metal selenide thin films and nanoparticles

    Science.gov (United States)

    Malik, Sajid N.; Akhtar, Masood; Revaprasadu, Neerish; Qadeer Malik, Abdul; Azad Malik, Mohammad

    2014-08-01

    We report here a new synthetic approach for convenient and high yield synthesis of dialkyldiselenophosphinato-metal complexes. A number of diphenyldiselenophosphinato-metal as well as diisopropyldiselenophosphinato-metal complexes have been synthesized and used as precursors for deposition of semiconductor thin films and nanoparticles. Cubic Cu2-xSe and tetragonal CuInSe2 thin films have been deposited by AACVD at 400, 450 and 500 °C whereas cubic PbSe and tetragonal CZTSe thin films have been deposited through doctor blade method followed by annealing. SEM investigations revealed significant differences in morphology of the films deposited at different temperatures. Preparation of Cu2-xSe and In2Se3 nanoparticles using diisopropyldiselenophosphinato-metal precursors has been carried out by colloidal method in HDA/TOP system. Cu2-xSe nanoparticles (grown at 250 °C) and In2Se3 nanoparticles (grown at 270 °C) have a mean diameter of 5.0 ± 1.2 nm and 13 ± 2.5 nm, respectively.

  16. Removal of heavy metal ions from water by complexation-assisted ultrafiltration.

    Science.gov (United States)

    Trivunac, Katarina; Stevanovic, Slavica

    2006-06-01

    Toxic heavy metals in air, soil and water are global problems that are growing threat to the environment. Therefore, the removal and separation of toxic and environmentally relevant heavy metal ions are a technological challenge with respect to industrial and environmental application. A promising process for the removal of heavy metal ions from aqueous solutions involves bonding the metals to a bonding agent (such as macromolecular species), and then separating the loaded agents from wastewater by separation processes such as membrane filtration. The choice of water-soluble macroligands remains important for developing this technology. The effects of type of complexing agent, pH value and applied pressure on retention coefficients of Zn(II) and Cd(II) complexes were investigated. At best operating conditions (pH=9.0, p=300kPa) using diethylaminoethyl cellulose, the removal of Cd(2+) and Zn(2+) was more than 95% and 99%, respectively.

  17. Effects of lability of metal complex on free ion measurement using DMT.

    Science.gov (United States)

    Weng, Liping; Van Riemsdijk, Willem H; Temminghoff, Erwin J M

    2010-04-01

    Very low concentrations of free metal ion in natural samples can be measured using the Donnan membrane technique (DMT) based on ion transport kinetics. In this paper, the possible effects of slow dissociation of metal complexes on the interpretation of kinetic DMT are investigated both theoretically and experimentally. The expressions of the lability parameter, Lgrangian , were derived for DMT. Analysis of new experimental studies using synthetic solution containing NTA as the ligand and Cu(2+) ions shows that when the ionic strength is low (DMT measurement. In natural waters, dissolved organic matter (DOM) is the most important source of ligands that complex metals. By comparing the fraction of labile species measured using other dynamic sensors (DGT, GIME) in several freshwaters, it is concluded that in most waters ion transport in DMT is controlled by diffusion in the membrane. Only in very soft waters (DMT. In this case, neglecting this effect may lead to an underestimation of the free metal ion concentration measured.

  18. Imidazolin-2-iminato complexes of rare earth metals with very short metal-nitrogen bonds: experimental and theoretical studies.

    Science.gov (United States)

    Panda, Tarun K; Trambitas, Alexandra G; Bannenberg, Thomas; Hrib, Cristian G; Randoll, Sören; Jones, Peter G; Tamm, Matthias

    2009-06-15

    The reactions of 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (Im(Dipp)NH, 1-H) with trimethylsilylmethyl lithium (LiCH(2)SiMe(3)) and anhydrous rare earth metal trichlorides MCl(3) afforded the imidazolin-2-iminato complexes [(1)MCl(2)(THF)(3)] (2a, M = Sc; 2b, M = Y; 2c, M = Lu) and [(1)GdCl(2)(THF)(2)] x [LiCl(THF)(2)] (2d). Treatment of complexes 2 with dipotassium cyclooctatetradienide, K(2)(C(8)H(8)) resulted in the formation of two- or three-legged piano-stool complexes of the type [(eta(8)-C(8)H(8))M(1)(THF)(n)] (3a, M = Sc, n = 1; 3b, M = Y, n = 2; 3c, M = Lu, n = 2; 3d, M = Gd, n = 2). X-ray diffraction analyses of all eight complexes 2 and 3 revealed the presence of very short metal-nitrogen bonds, which are among the shortest ever observed for these elements. [(eta(8)-C(8)H(8))Sc(1)(THF)] (3a) reacted with 2,6-dimethylphenyl isothiocyanate (Xy-NCS) to form the [2 + 2]-cycloaddition product 4, which contains a thioureato-N,N' moiety. The related COT-titanium complex [(eta(8)-C(8)H(8))TiCl(1)] (6) could be obtained from [(1)TiCl(3)] (5) by reaction with K(2)(C(8)H(8)) and was structurally characterized. As a theoretical analysis of the nature of the metal-nitrogen bond, density functional theory (DFT) calculations have been carried out for complexes 3a and 6 and also for the model complexes [(eta(8)-C(8)H(8))Sc(NIm(Me))] (7), [(eta(8)-C(8)H(8))Ti(NIm(Me))](+) (8), and [(eta(8)-C(8)H(8))Ti(NXy)] (9), revealing a marked similarity of the bonding in imidazolin-2-iminato and conventional imido metal complexes.

  19. Metal distributions in complexes with Chlorella vulgaris in seawater and wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Pascucci, P.R.; Kowalak, A.D.

    1999-10-01

    Divalent cadmium (Cd), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn) simultaneous complexes with an algal biomass Chlorella vulgaris were studied for bioremediation purposes in various aqueous media: distilled-deionized water (DDIW), seawater, nuclear-reactor pool water, and process wastewater. Reactions were monitored using various dry masses of algae at constant temperature and constant metal concentrations for reaction times ranging from 0 to 150 minutes. Complexes occurred within 30 minutes and reached a steady state after 80 to 120 minutes. Distribution constants (K{prime}{sub d}) were calculated for the complexes and relative orders of K{prime}{sub d} were reported. The K{prime}{sub d} are used to evaluate relative efficiency of metal remediation from waters. Lead, Cu, and Ni complexes had the greatest K{prime}{sub d} values and those metals were most efficiently removed from these waters. Zinc and Fe formed the most labile complexes. The order of K{prime}{sub d} values for complexes in DDIW was Pb > Cu > Cd > Zn, then Cu > Cd > Zn in seawater, Cd > Cu > Zn in reactor pool water, and Ni > Cd > Cu > Zn > Fe in wastewater. C. vulgaris biomass may potentially be used as an alternative to traditional water treatment methods for simultaneous extraction of metals from seawater, process wastewater, or drinking water.

  20. Synthesis, Characterization and Biological Evaluation of Transition Metal Complexes Derived from N, S Bidentate Ligands

    Directory of Open Access Journals (Sweden)

    Enis Nadia Md Yusof

    2015-05-01

    Full Text Available Two bidentate NS ligands were synthesized by the condensation reaction of S-2-methylbenzyldithiocarbazate (S2MBDTC with 2-methoxybenzaldehyde (2MB and 3-methoxybenzaldehyde (3MB. The ligands were reacted separately with acetates of Cu(II, Ni(II and Zn(II yielding 1:2 (metal:ligand complexes. The metal complexes formed were expected to have a general formula of [M(NS2] where M = Cu2+, Ni2+, and Zn2+. These compounds were characterized by elemental analysis, molar conductivity, magnetic susceptibility and various spectroscopic techniques. The magnetic susceptibility measurements and spectral results supported the predicted coordination geometry in which the Schiff bases behaved as bidentate NS donor ligands coordinating via the azomethine nitrogen and thiolate sulfur. The molecular structures of the isomeric S2M2MBH (1 and S2M3MBH (2 were established by X-ray crystallography to have very similar l-shaped structures. The Schiff bases and their metal complexes were evaluated for their biological activities against estrogen receptor-positive (MCF-7 and estrogen receptor-negative (MDA-MB-231 breast cancer cell lines. Only the Cu(II complexes showed marked cytotoxicity against the cancer cell lines. Both Schiff bases and other metal complexes were found to be inactive. In concordance with the cytotoxicity studies, the DNA binding studies indicated that Cu(II complexes have a strong DNA binding affinity.

  1. Pharmacological Evaluation of Naproxen Metal Complexes on Antinociceptive, Anxiolytic, CNS Depressant, and Hypoglycemic Properties

    Science.gov (United States)

    Das, Narhari; Abdur Rahman, S. M.

    2016-01-01

    Purpose. The present study was designed to investigate the antinociceptive, anxiolytic, CNS depressant, and hypoglycemic effects of the naproxen metal complexes. Methods. The antinociceptive activity was evaluated by acetic acid-induced writhing method and radiant heat tail-flick method while anxiolytic activity was evaluated by elevated plus maze model. The CNS depressant activity of naproxen metal complexes was assessed using phenobarbitone-induced sleeping time test and the hypoglycemic test was performed using oral glucose tolerance test. Results. Metal complexes significantly (P < 0.001) reduced the number of abdominal muscle contractions induced by 0.7% acetic acid solution in a dose dependent manner. At the dose of 25 mg/kg body weight p.o. copper, cobalt, and zinc complexes exhibited higher antinociceptive activity having 59.15%, 60.56%, and 57.75% of writhing inhibition, respectively, than the parent ligand naproxen (54.93%). In tail-flick test, at both doses of 25 and 50 mg/kg, the copper, cobalt, silver, and zinc complexes showed higher antinociceptive activity after 90 minutes than the parent drug naproxen. In elevated plus maze (EPM) model the cobalt and zinc complexes of naproxen showed significant anxiolytic effects in dose dependent manner, while the copper, cobalt, and zinc complexes showed significant CNS depressant and hypoglycemic activity. Conclusion. The present study demonstrated that copper, cobalt, and zinc complexes possess higher antinociceptive, anxiolytic, CNS depressant, and hypoglycemic properties than the parent ligand. PMID:27478435

  2. Complexation with dissolved organic matter and solubility control of heavy metals in a sandy soil.

    Science.gov (United States)

    Weng, Liping; Temminghoff, Erwin J M; Lofts, Stephen; Tipping, Edward; Van Riemsdijk, Willem H

    2002-11-15

    The complexation of heavy metals with dissolved organic matter (DOM) in the environment influences the solubility and mobility of these metals. In this paper, we measured the complexation of Cu, Cd, Zn, Ni, and Pb with DOM in the soil solution at pH 3.7-6.1 using a Donnan membrane technique. The results show that the DOM-complexed species is generally more significant for Cu and Pb than for Cd, Zn, and Ni. The ability of two advanced models for ion binding to humic substances, e.g., model VI and NICA-Donnan, in the simulation of metal binding to natural DOM was assessed by comparing the model predictions with the measurements. Using the default parameters of fulvic and humic acid, the predicted concentrations of free metal ions from the solution speciation calculation using the two models are mostly within 1 order of magnitude difference from the measured concentrations, except for Ni and Pb in a few samples. Furthermore, the solid-solution partitioning of the metals was simulated using a multisurface model, in which metal binding to soil organic matter, dissolved organic matter, clay, and iron hydroxides was accounted for using adsorption and cation exchange models (NICA-Donnan, Donnan, DDL, CD-MUSIC). The model estimation of the dissolved concentration of the metals is mostly within 1 order of magnitude difference from those measured except for Ni in some samples and Pb. The solubility of the metals depends mainly on the metal loading over soil sorbents, pH, and the concentration of inorganic ligands and DOM in the soil solution.

  3. Multifunctionality of organometallic quinonoid metal complexes: surface chemistry, coordination polymers, and catalysts.

    Science.gov (United States)

    Kim, Sang Bok; Pike, Robert D; Sweigart, Dwight A

    2013-11-19

    Quinonoid metal complexes have potential applications in surface chemistry, coordination polymers, and catalysts. Although quinonoid manganese tricarbonyl complexes have been used as secondary building units (SBUs) in the formation of novel metal-organometallic coordination networks and polymers, the potentially wider applications of these versatile linkers have not yet been recognized. In this Account, we focus on these diverse new applications of quinonoid metal complexes, and report on the variety of quinonoid metal complexes that we have synthesized. Through the use of [(η(6)-hydroquinone)Mn(CO)3](+), we are able to modify the surface of Fe3O4 and FePt nanoparticles (NPs). This process occurs either by the replacement of oleylamine with neutral [(η(5)-semiquinone)Mn(CO)3] at the NP surface, or by the binding of anionic [(η(4)-quinone)Mn(CO)3](-) upon further deprotonation of [(η(5)-semiquinone)Mn(CO)3] at the NP surface. We have demonstrated chemistry at the intersection of surface-modified NPs and coordination polymers through the growth of organometallic coordination polymers onto the surface modified Fe3O4 NPs. The resulting magnetic NP/organometallic coordination polymer hybrid material exhibited both the unique superparamagnetic behavior associated with Fe3O4 NPs and the paramagnetism attributable to the metal nodes, depending upon the magnetic range examined. By the use of functionalized [(η(5)-semiquinone)Mn(CO)3] complexes, we attained the formation of an organometallic monolayer on the surface of highly ordered pyrolitic graphite (HOPG). The resulting organometallic monolayer was not simply a random array of manganese atoms on the surface, but rather consisted of an alternating "up and down" spatial arrangement of Mn atoms extending from the HOPG surface due to hydrogen bonding of the quinonoid complexes. We also showed that the topology of metal atoms on the surface could be controlled through the use of quinonoid metal complexes. A quinonoid

  4. Structural and Spectral Properties of Curcumin and Metal- Curcumin Complex Derived from Turmeric (Curcuma longa)

    Science.gov (United States)

    Bich, Vu Thi; Thuy, Nguyen Thi; Binh, Nguyen Thanh; Huong, Nguyen Thi Mai; Yen, Pham Nguyen Dong; Luong, Tran Thanh

    Structural and spectral properties of curcumin and metal- curcumin complex derived from turmeric (Curcuma longa) were studied by SEM and vibrational (FTIR and Raman) techniques. By comparison between curcumin commercial, fresh turmeric and a yellow powder obtained via extraction and purification of turmeric, we have found that this insoluble powder in water is curcumin. The yellow compound could complex with certain ion metal and this metal-curcumin coloring complex is water soluble and capable of producing varying hues of the same colors and having antimicrobial, cytotoxicity activities for use in foodstuffs and pharmacy. The result also demonstrates that Micro-Raman spec-troscopy is a valuable non-destructive tool and fast for investigation of a natural plant even when occurring in low concentrations.

  5. Detection of heavy metals in water using dye nano-complexants and a polymeric film.

    Science.gov (United States)

    Hadar, Hodayah Abuhatzira; Bulatov, Valery; Dolgin, Bella; Schechter, Israel

    2013-09-15

    An optical analytical method, based on complexation reactions of organic azo-dyes with heavy metals, is proposed. It is based on a specially designed polymeric film that when submerged in water contaminated with heavy metals it changes its color. The azo-dyes are injected into the tested water, resulting in formation of nano-particles of insoluble complexes. The polymeric film embeds and dissolves these nano-particles and thus allows for spectral and/or visual analysis. This film consists of a PVC polymeric skeleton and an organic solvent, bis(2-ethylhexyl)phthalate, which possesses high affinity to the heavy metal nano-complexes. The method was exemplified for Cd, Ni and Co ions. The method is sensitive in the sub-ppm range. The mechanism and kinetics of the film coloration were reported.

  6. Microwave irradiation assisted, one pot synthesis of simple and complex metal oxide nanoparticles: a general approach

    Science.gov (United States)

    Brahma, Sanjaya; Liu, Chuan-Pu; Shivashankar, S. A.

    2017-10-01

    We demonstrate a standard approach for the growth of binary/ternary metal oxide nanostructures within 5 min at a low temperature (Nanoparticles of some functionally advanced binary/ternary metal oxides (MnO2, Fe2O3, NiO, CdO, Ga2O3, Gd2O3, ZnFe2O4, ZnMn2O4) are synthesized and the structure/microstructure is analyzed to ensure the phase and crystallinity. This synthesis procedure can be extended to the large scale production of many other simple and complex metal oxides.

  7. Speciation of phytate ion in aqueous solution. Alkali metal complex formation in different ionic media.

    Science.gov (United States)

    De Stefano, Concetta; Milea, Demetrio; Pettignano, Alberto; Sammartano, Silvio

    2003-08-01

    The acid-base properties of phytic acid [ myo-inositol 1,2,3,4,5,6-hexakis(dihydrogen phosphate)] (H(12)Phy; Phy(12-)=phytate anion) were studied in aqueous solution by potentiometric measurements ([H+]-glass electrode) in lithium and potassium chloride aqueous media at different ionic strengths (0iodide (Et(4)NI; e.g., at I=0.5 mol L(-1), log K(3)(H)=11.7, 8.0, 9.1, and 9.1 in Et(4)NI, LiCl, NaCl and KCl, respectively; the protonation constants in Et(4)NI and NaCl were already reported), owing to the strong interactions occurring between the phytate and alkaline cations present in the background salt. We explained this in terms of complex formation between phytate and alkali metal ions. Experimental evidence allows us to consider the formation of 13 mixed proton-metal-ligand complexes, M(j)H(i)Phy((12-i-j)-), (M+ =Li+, Na+, K+), with jstability of alkali metal complexes follows the trend Li+ > or =Na+K+. Some measurements were also performed at constant ionic strength (I=0.5 mol L(-1)), using different mixtures of Et(4)NI and alkali metal chlorides, in order to confirm the formation of hypothesized and calculated metal-proton-ligand complex species and to obtain conditional protonation constants in these multi-component ionic media.

  8. Photoactivatable metal complexes: from theory to applications in biotechnology and medicine.

    Science.gov (United States)

    Smith, Nichola A; Sadler, Peter J

    2013-07-28

    This short review highlights some of the exciting new experimental and theoretical developments in the field of photoactivatable metal complexes and their applications in biotechnology and medicine. The examples chosen are based on some of the presentations at the Royal Society Discussion Meeting in June 2012, many of which are featured in more detail in other articles in this issue. This is a young field. Even the photochemistry of well-known systems such as metal-carbonyl complexes is still being elucidated. Striking are the recent developments in theory and computation (e.g. time-dependent density functional theory) and in ultrafast-pulsed radiation techniques which allow photochemical reactions to be followed and their mechanisms to be revealed on picosecond/nanosecond time scales. Not only do some metal complexes (e.g. those of Ru and Ir) possess favourable emission properties which allow functional imaging of cells and tissues (e.g. DNA interactions), but metal complexes can also provide spatially controlled photorelease of bioactive small molecules (e.g. CO and NO)--a novel strategy for site-directed therapy. This extends to cancer therapy, where metal-based precursors offer the prospect of generating excited-state drugs with new mechanisms of action that complement and augment those of current organic photosensitizers.

  9. Structure and properties of alizarin complex formed with alkali metal hydroxides in methanol solution.

    Science.gov (United States)

    Jeliński, Tomasz; Cysewski, Piotr

    2016-06-01

    Quantum chemical computations were used for prediction of the structure and color of alizarin complex with alkali metal hydroxides in methanolic solutions. The color prediction relying on the single Gaussian-like band once again proved the usefulness of the PBE0 density functional due to the observed smallest color difference between computed and experimentally derived values. It was found that the alkali metal hydroxide molecules can bind to the two oxygen atoms of both hydroxyl groups of alizarin or to one of these atoms and the oxygen atom from the keto group in a complex with three methanol molecules. This means that two electronic transitions need to be taken into account when considering the spectra of the studied complexes. The resulting bond lengths and angles are correlated with the properties of the alkali metal atoms. The molar mass, the atomic radius, and the Pauling electronegativity of studied metals are quite accurate predictors of the geometric properties of hydroxide complexes with alizarin in methanol solution. Graphical abstract The spectra of the neutral and monoanionic form of alizarin together with color changes resulting from addition of different metal hydroxides and represented in CIE color space.

  10. Pesticides Curbing Soil Fertility: Effect of Complexation of Free Metal Ions

    KAUST Repository

    Kaur, Sukhmanpreet

    2017-07-04

    Researchers have suggested that the reason behind infertility is pernicious effect of broad spectrum pesticides on non target, beneficial microorganism of soil. Here, studying the chelating effect of selective organophosphate and carbamate pesticides with essential metal ions, at all possible combinations of three different pH (4 ± 0.05, 7 ± 0.05 and 9 ± 0.05) and three different temperatures (15 ± 0.5°C, 30 ± 0.5°C and 45 ± 0.5°C), shows very fast rate of reaction which further increases with increase of pH and temperature. Carbonyl oxygen of carbamate and phosphate oxygen of organophosphate were found to be common ligating sites among all the complexes. Formed metal complexes were found to be highly stable and water insoluble on interaction with essential metal ions in solvent medium as well as over silica. Density functional theory (DFT) calculations not only reinforced the experimental observations, but, after a wide computational conformational analysis, unraveled the nature of the high stable undesired species that consist of pesticides complexed by metal ions from the soil. All in all, apart from the direct toxicity of pesticides, the indirect effect by means of complexation of free metal ions impoverishes the soil.

  11. Density functional theory study on Herzberg-Teller contribution in Raman scattering from 4-aminothiophenol-metal complex and metal-4-aminothiophenol-metal junction

    Science.gov (United States)

    Liu, Shasha; Zhao, Xiuming; Li, Yuanzuo; Zhao, Xiaohong; Chen, Maodu

    2009-06-01

    Density functional theory (DFT) and time-dependent DFT calculations have been performed to investigate the Raman scattering spectra of metal-molecule complex and metal-molecule-metal junction architectures interconnected with 4-aminothiophenol (PATP) molecule. The simulated profiles of normal Raman scattering (NRS) spectra for the two complexes (Ag2-PATP and PATP-Au2) and the two junctions (Ag2-PATP-Au2 and Au2-PATP-Ag2) are similar to each other, but exhibit obviously different Raman intensities. Due to the lager static polarizabilities of the two junctions, which directly influence the ground state chemical enhancement in NRS spectra, the calculated normal Raman intensities of them are stronger than those of two complexes by the factor of 102. We calculate preresonance Raman scattering (RRS) spectra with incident light at 1064 nm, which is much lower than the S1 electronic transition energy of complexes and junctions. Ag2-PATP-Au2 and Au2-PATP-Ag2 junctions yield higher Raman intensities than those of Ag2-PATP and PATP-Au2 complexes, especially for b2 modes. This effect is mainly attributed to charge transfer (CT) between the metal gap and the PAPT molecule which results in the occurrence of CT resonance enhancement. The calculated pre-RRS spectra strongly depend on the electronic transition state produced by new structures. With excitation at 514.5 nm, the calculated pre-RRS spectra of two complexes and two junctions are stronger than those of with excitation at 1064 nm. A charge difference densities methodology has been used to visually describe chemical enhancement mechanism of RRS spectrum. This methodology aims at visualizing intermolecular CT which provides direct evidence of the Herzberg-Teller mechanism.

  12. Journal bearing

    Science.gov (United States)

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

    1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

  13. Transition Metal Complexes of Isonicotinoyl–hydrazone-4-diphenylaminobenzaldehyde: Synthesis, Characterization and Antimicrobial Studies

    Directory of Open Access Journals (Sweden)

    L. Mitu

    2012-01-01

    Full Text Available A series of complexes of Cu(II, Ni(II, Co(II, Mn(II and Cd(II with Isonicotinoylhydrazone-4-diphenylaminobenzaldehyde (INHDAB has been reported. The complexes have been characterized by analytical data, IR, UV-Vis, NMR spectra, magnetic susceptibility values, thermal analysis and for the Cu(II complex the ESR spectrum has been registered. The biological activity of these complexes were investigated against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Shigella flexneri bacteria. The INHDAB ligand is coordinate at the metallic ions by oxygen amide (O=C and the azomethine nitrogen.

  14. Zr-in-rutile resetting in aluminosilicate bearing ultra-high temperature granulites: Refining the record of cooling and hydration in the Napier Complex, Antarctica

    Science.gov (United States)

    Mitchell, Ruairidh J.; Harley, Simon L.

    2017-02-01

    The relative validity and closure temperature of the Zr-in-rutile thermometer for recording UHT metamorphism are process dependent and hotly debated. We present an integrated petrological approach to Zr-in-rutile thermometry including phase equilibrium (pseudosection) modelling in complex chemical systems with updated mineral a-X models and systematic in-situ microanalysis of rutile. This study is centred on high-pressure rutile bearing UHT granulites from Mt. Charles, Napier Complex, Antarctica. P-T phase equilibrium modelling of two garnet bearing granulites (samples 49677, 49701) constrains an overall post-peak near isobaric cooling (IBC) evolution for the Napier Complex at Mt. Charles; from 14 kbar, 1100 °C with moderate decompression to 11 kbar, 800-900 °C. Local hydration on cooling over this temperature range is recorded in a kyanite bearing granulite (sample 49688) with an inferred injection of aqueous fluid equivalent to up to 9 mol% H2O from T-MH2O modelling. Further late stage cooling to < 740 °C is recorded by voluminous retrograde mica growth and partial preservation of a ky-pl-kfs-bt-liq bearing equilibrium assemblage. Overall, Zr-in-rutile temperatures at 11 kbar (Tomkins et al., 2007) are reset to between 606 °C and 780 °C across all samples, with flat core-rim Zr concentration profiles in all rutiles. However, zircon precipitates as inclusions, needle exsolutions, or rods along rutile grain boundaries are recrystallised from rutiles in qz/fsp domains. Reintegrating the Zr-in-rutile concentration 'lost' via the recrystallisation of these zircon precipitates (e.g. Pape et al., 2016) can recover maximum concentrations of up to 2.2 wt% and thus maximum peak temperatures of 1149 °C at 11 kbar. Rutile Nb-Ta signatures and rounded rutile grains without zircon precipitates in hydrated mica domains in sample 49688 provide evidence for fluid-mediated mobility of Zr and Nb during retrograde cooling in hydrated lithologies. Aqueous fluid supplemented

  15. Density functional calculations on electronic circular dichroism spectra of chiral transition metal complexes.

    Science.gov (United States)

    Autschbach, Jochen; Jorge, Francisco E; Ziegler, Tom

    2003-05-05

    Time-dependent density functional theory (TD-DFT) has for the first time been applied to the computation of circular dichroism (CD) spectra of transition metal complexes, and a detailed comparison with experimental spectra has been made. Absorption spectra are also reported. Various Co(III) complexes as well as [Rh(en)(3)](3+) are studied in this work. The resulting simulated CD spectra are generally in good agreement with experimental spectra after corrections for systematic errors in a few of the lowest excitation energies are applied. This allows for an interpretation and assignment of the spectra for the whole experimentally accessible energy range (UV/vis). Solvent effects on the excitations are estimated via inclusion of a continuum solvent model. This significantly improves the computed excitation energies for charge-transfer bands for complexes of charge +3, but has only a small effect on those for neutral or singly charged complexes. The energies of the weak d-to-d transitions of the Co complexes are systematically overestimated due to deficiencies of the density functionals. These errors are much smaller for the 4d metal complex. Taking these systematic errors and the effect of a solvent into consideration, TD-DFT computations are demonstrated to be a reliable tool in order to assist with the assignment and interpretation of CD spectra of chiral transition metal complexes.

  16. Transition Metal Complexes of Naproxen: Synthesis, Characterization, Forced Degradation Studies, and Analytical Method Verification

    Directory of Open Access Journals (Sweden)

    Md. Sharif Hasan

    2016-01-01

    Full Text Available The aim of our current research was to synthesize some transition metal complexes of Naproxen, determine their physical properties, and examine their relative stability under various conditions. Characterizations of these complexes were done by 1H-NMR, Differential Scanning Calorimetry (DSC, FT-IR, HPLC, and scanning electron microscope (SEM. Complexes were subjected to acidic, basic, and aqueous hydrolysis as well as oxidation, reduction, and thermal degradation. Also the reversed phase high-performance liquid chromatography (RP-HPLC method of Naproxen outlined in USP was verified for the Naproxen-metal complexes, with respect to accuracy, precision, solution stability, robustness, and system suitability. The melting points of the complexes were higher than that of the parent drug molecule suggesting their thermal stability. In forced degradation study, complexes were found more stable than the Naproxen itself in all conditions: acidic, basic, oxidation, and reduction media. All the HPLC verification parameters were found within the acceptable value. Therefore, it can be concluded from the study that the metal complexes of Naproxen can be more stable drug entity and offer better efficacy and longer shelf life than the parent Naproxen.

  17. Magnetic interactions as a stabilizing factor of semiquinone species of lawsone by metal complexation

    Energy Technology Data Exchange (ETDEWEB)

    Valle-Bourrouet, Grettel [Universidad de Costa Rica, Escuela de Quimica, San Jose (Costa Rica); Ugalde-Saldivar, Victor M. [Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, C.P. 04510, Mexico, D.F. (Mexico); Gomez, Martin [Departamento de Sistemas Biologicos, Universidad Autonoma Metropolitana-Xochimilco, C.P. 04960, Mexico, D.F. (Mexico); Ortiz-Frade, Luis A. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Parque Tecnologico Queretaro, Sanfandila, 76703, Pedro Escobedo, Queretaro (Mexico); Gonzalez, Ignacio [Universidad Autonoma Metropolitana - Iztapalapa, Departamento de Quimica, Area de Electroquimica, Apartado postal 55-534, 09340, Mexico, D.F. (Mexico); Frontana, Carlos, E-mail: ultrabuho@yahoo.com.m [Departamento de Quimica, Centro de Investigacion y Estudios Avanzados, Av. Instituto Politecnico Nacional No. 2508 Col. San Pedro Zacatenco, C.P. 07360, Mexico, D.F. (Mexico)

    2010-12-01

    Changes in electrochemical reactivity for lawsone anions (lawsone, 2-hydroxy-1,4-naphthoquinone, HLw) being coordinated to a series of metallic ions in dimethylsulfoxide solution were evaluated. Upon performing cyclic voltammetry experiments for metal complexes of this quinone with pyridine (Py) - structural formula M(II)(Lw{sup -}){sub 2}(Py){sub 2}; M: Co(II), Ni(II), Zn(II) - it was found that the reduction of coordinated Lw{sup -} units occurs during the first and second electron uptake in the analyzed compounds. The stability of the electrogenerated intermediates for each complex depends on the d electron configuration in each metal center and is determined by magnetic interactions with the available spins considering an octahedral conformation for all the compounds. This was evidenced by in situ spectroelectrochemical-ESR measurements in the Zn(II) complex in which due to the lack of magnetic interaction owing to its electron configuration, the structure of the coordinated anion radical species was determined. Successive reduction of the associated Lw{sup -} units leads to partial dissociation of the complex, determined by the identification of free radical dianion structures in solution. These results show some insights on how metal-lawsone complexation can modify the solution reactivity and stability of the electrogenerated radical species.

  18. [Ultraviolet-visible spectrometry analysis of insoluble xanthate heavy metal complexes].

    Science.gov (United States)

    Qiu, Bo; Liu, Jin-Feng; Liu, Yao-Chi; Yang, Zhao-Guang; Li, Hai-Pu

    2014-11-01

    A ultraviolet-visible spectrometry method of determining insoluble xanthate heavy metal complexes in flotation wastewater was the first time to be put forward. In this work, the changes of ultraviolet-visible spectra of xanthate solution after the addition of various heavy metal ions were investigated firstly. It was found that Pb2+ and Cu2+ can form insoluble complexes with xanthate, while Fe2+, Zn2+ and Mn2+ have little effect on the ultraviolet absorption of xanthate solution. Then the removal efficiencies of filter membrane with different pore sizes were compared, and the 0.22 μm membrane was found to be effective to separate copper xanthate or lead xanthate from the filtrate. Furthermore, the results of the study on the reaction of sodium sulfide and insoluble xanthate heavy metal complexes showed that S(2-) can release the xanthate ion quantitatively from insoluble complexes to solution. Based on the above research, it was concluded that the amount of insoluble xanthate heavy metal complexes in water samples can be obtained through the increase of free xanthate in the filtrate after the addition of sodium sulfide. Finally, the feasibility of this method was verified by the application to the analysis of flotation wastewater from three ore-dressing plants in the Thirty-six Coves in Chenzhou.

  19. Metal oxalate complexes as novel inorganic dopants: Studies on their effect on conducting polyaniline

    Indian Academy of Sciences (India)

    R Murugesan; E Subramanian

    2002-12-01

    Doped polyaniline materials with metal oxalate complexes of Cr, Fe, Mn, Co and Al were synthesized by in situ chemical oxidative polymerization of aniline using potassium perdisulphate as oxidant in aqueous sulphuric acid medium. These polymer materials were characterized by chemical analyses, spectral studies (UV-visible and IR), X-ray diffraction and thermal techniques and also by conductivity measurements by four-probe technique. The presence of complex anion in polyaniline material was confirmed by chemical and spectral analyses. The yield and conductivity of metal oxalate doped polyanilines were found to be high when compared to the simple sulphate ion doped polyaniline prepared under similar condition. UV-visible and IR spectral features not only confirmed the polyaniline doping by complex anions but also substantiated their facilitating effect on conductivity. The X-ray diffraction patterns indicated some crystalline nature in metal oxalate doped polyaniline and amorphous in polyaniline sulphate salt. The conductivity of the polymer samples strongly depended on the degree of crystallinity induced by complex counter anions as dopant. All the polymer materials, as evident from TGA curves, were observed to undergo three-step degradation of water loss, de-doping and decomposition of polymer. Further, the thermal stability of polyaniline was found to improve on doping with metal oxalate complex.

  20. Metal complexes of chiral pentaazacrowns as conformational templates for β-turn recognition

    Science.gov (United States)

    Reaka, Andrea J. H.; Ho, Chris M. W.; Marshall, Garland R.

    2002-08-01

    Examples of reverse turns as recognition motifs in biological systems can be found in high-resolution crystal structures of antibody-peptide complexes. Development of peptidomimetics is often based on replacing the amide backbone of peptides by sugar rings, steroids, benzodiazepines, or other hetero- and carbocycles. In this approach, the chemical scaffold of the peptide backbone can be replaced while retaining activity as long as the pharmacophoric groups of the peptide side chains stay in relatively the same place; in other words, similar functional groups must overlap in space for interaction with critical receptor sites. This study evaluates the potential of metal complexes of chiral pentaazacrowns (PAC) derived by reduction of cyclic pentapeptides as β-turn mimetics. Due to the limited flexibility of the pendant chiral side groups in these metal complexes, one can potentially elicit information about the receptor-bound conformation from their binding affinities. 11 PAC crystal structures with different substitution patterns complexed with 3 different metals (Mn, Fe, Cd) as a prototypical database of potential side-chain orientations. Complexation with different metals induces subtle differences in the conformations of a particular azacrown scaffold. The lack of parameterization of transition metals for force field calculations precludes a thorough theoretical study. Thus, this study utilizes a simple geometrical comparison between the experimental data for crystalline PAC complexes and the side-chain orientations seen in classic β-turns. The FOUNDATION program was used to overlap the Cα-Cβ vectors of the corresponding ideal β-turn side-chains to all possible leaving groups of the PAC complexes. When comparing the relative orientations of the chiral side chains, a strong overlap of the bonds (between about 0.1 Å to about 0.5 Å RMS for 3 residues and up to about 1 Å RMS for 4 residues) was observed for many of the molecules. Such metal complexes may lack

  1. Metal complexes of chiral pentaazacrowns as conformational templates for beta-turn recognition.

    Science.gov (United States)

    Reaka, Andrea J H; Ho, Chris M W; Marshall, Garland R

    2002-01-01

    Examples of reverse turns as recognition motifs in biological systems can be found in high-resolution crystal structures of antibody-peptide complexes. Development of peptidomimetics is often based on replacing the amide backbone of peptides by sugar rings, steroids, benzodiazepines, or other hetero- and carbocycles. In this approach, the chemical scaffold of the peptide backbone can be replaced while retaining activity as long as the pharmacophoric groups of the peptide side chains stay in relatively the same place; in other words, similar functional groups must overlap in space for interaction with critical receptor sites. This study evaluates the potential of metal complexes of chiral pentaazacrowns (PAC) derived by reduction of cyclic pentapeptides as beta-turn mimetics. Due to the limited flexibility of the pendant chiral side groups in these metal complexes, one can potentially elicit information about the receptor-bound conformation from their binding affinities. 11 PAC crystal structures with different substitution patterns complexed with 3 different metals (Mn, Fe, Cd) as a prototypical database of potential side-chain orientations. Complexation with different metals induces subtle differences in the conformations of a particular azacrown scaffold. The lack of parameterization of transition metals for force field calculations precludes a thorough theoretical study. Thus, this study utilizes a simple geometrical comparison between the experimental data for crystalline PAC complexes and the side-chain orientations seen in classic beta-turns. The FOUNDATION program was used to overlap the Calpha-Cbeta vectors of the corresponding ideal beta-turn side-chains to all possible leaving groups of the PAC complexes. When comparing the relative orientations of the chiral side chains, a strong overlap of the bonds (between about 0.1 A to about 0.5 A RMS for 3 residues and up to about 1 A RMS for 4 residues) was observed for many of the molecules. Such metal complexes

  2. Synthesis and Selective Coloration of Monoaza Crown Ethers Bearing Picrylamino-type Side Arms for Alkali Metal Salts and Methylamine

    Institute of Scientific and Technical Information of China (English)

    Wei ZENG; Zhi Hua MAO; Mi GONG; Chun Chun ZHANG; Sheng Ying QIN; Jun SU

    2003-01-01

    N-pivot lariat ethers with picrylamino group as a chromophore (1, 2 and 3) have been prepared by reaction of N-(4-aminoaryl)monoaza crown ethers with picryl chrolide, and the selective coloration of 1, 2 and 3 for alkali metal salts and amines has been studied by UV-Vis spectra.

  3. Synthesis and thermal studies of tetraaza macrocylic ligand and its transition metal complexes. DNA binding affinity of copper complex.

    Science.gov (United States)

    Saif, M; Mashaly, Mahmoud M; Eid, Mohamed F; Fouad, R

    2011-09-01

    A Tetraaza Macrocylic Ligand (H2L) and its complexes, [Cd(H2L)(OH2)2](NO3)(2)·1/2OH2 (I), [Co(H2L)(OH2)](NO3)(2)·1/2OH2 (II), [Cu(H2L)(NO3)2]·3/2OH2 (III) and [Ni(H2L)(NO3)(OH2)]NO3·OH2 (IV), have been synthesized and characterized on the basis of elemental analysis, molar conductivity, 1H NMR, UV-vis, FT-IR and mass spectroscopy. All results confirm that the prepared compounds have 1:1 metal-to-ligand stoichiometry, octahedral configuration and the ligand behaves as a neutral tetradendate towards the metal ions. [CdL(OH2)2] (V), [CoL(OH2)2] (VI), [CuL(OH2)2] (VII) and [Ni(H2L)(NO3)2] (VIII) were synthesized pyrolytically in solid state from corresponding compounds (I-IV). Analytical results of complexes (V-VIII) show that the ligand behaves either as a neutral tetradendate or dianionic tetradentate ligand towards the metal ions. The binding of H2L and its copper complex (III) to DNA has been investigated by ultraviolet absorption spectroscopy. The experiments indicate that H2L and its copper complex (III) can bind to DNA through an intercalative mode. The H2L and its copper complex (III) exhibited anti-tumor activity against Ehrlich Acites Carcinoma (E.A.C) at the concentration of 100 μg/ml.

  4. Synthesis and thermal studies of tetraaza macrocylic ligand and its transition metal complexes. DNA binding affinity of copper complex

    Science.gov (United States)

    Saif, M.; Mashaly, Mahmoud M.; Eid, Mohamed F.; Fouad, R.

    2011-09-01

    A Tetraaza Macrocylic Ligand (H 2L) and its complexes, [Cd(H 2L)(OH 2) 2](NO 3) 2·1/2OH 2 (I), [Co(H 2L)(OH 2)](NO 3) 2·1/2OH 2 (II), [Cu(H 2L)(NO 3) 2]·3/2OH 2 (III) and [Ni(H 2L)(NO 3)(OH 2)]NO 3·OH 2 (IV), have been synthesized and characterized on the basis of elemental analysis, molar conductivity, 1H NMR, UV-vis, FT-IR and mass spectroscopy. All results confirm that the prepared compounds have 1:1 metal-to-ligand stoichiometry, octahedral configuration and the ligand behaves as a neutral tetradendate towards the metal ions. [CdL(OH 2) 2] (V), [CoL(OH 2) 2] (VI), [CuL(OH 2) 2] (VII) and [Ni(H 2L)(NO 3) 2] (VIII) were synthesized pyrolytically in solid state from corresponding compounds (I-IV). Analytical results of complexes (V-VIII) show that the ligand behaves either as a neutral tetradendate or dianionic tetradentate ligand towards the metal ions. The binding of H 2L and its copper complex (III) to DNA has been investigated by ultraviolet absorption spectroscopy. The experiments indicate that H 2L and its copper complex (III) can bind to DNA through an intercalative mode. The H 2L and its copper complex (III) exhibited anti-tumor activity against Ehrlich Acites Carcinoma (E.A.C) at the concentration of 100 μg/ml.

  5. Effect of fermented non-starch polysaccharide complexes on sorption of heavy metal ions in biological systems

    Directory of Open Access Journals (Sweden)

    L. E. Glagoleva

    2013-01-01

    Full Text Available Hydrolytic action enzyme for modification of nonstarch polysaccharide complexes was developed and studied their influence on sorption activity in relation to heavy metals in biosystem.

  6. Ab initio calculations on the magnetic properties of transition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    Bodenstein, Tilmann; Fink, Karin [Karlsruhe Institute of Technology, Institute of Nanotechnology, POB 3640, 76021 Karlsruhe (Germany)

    2015-12-31

    We present a protocol for the ab initio determination of the magnetic properties of mono- and polynuclear transition metal compounds. First, we obtain the low lying electronic states by multireference methods. Then, we include spin-orbit coupling and an external magnetic field for the determination of zero-field splitting and g-tensors. For the polynuclear complexes the magnetic exchange coupling constants are determined by a modified complete active space self consistent field method. Based on the results of the ab initio calculations, magnetic data such as magnetic susceptibility or magnetization are simulated and compared to experimental data. The results obtained for the polynuclear complexes are further analysed by calculations on model complexes where part of the magnetic centers are substituted by diamagnetic ions. The methods are applied to different Co and Ni containing transition metal complexes.

  7. Transition Metal(II Complexes with Cefotaxime-Derived Schiff Base: Synthesis, Characterization, and Antimicrobial Studies

    Directory of Open Access Journals (Sweden)

    Aurora Reiss

    2014-01-01

    Full Text Available New [ML2(H2O2] complexes, where M = Co(II, Ni(II, Cu(II, and Zn(II while L corresponds to the Schiff base ligand, were synthesized by condensation of cefotaxime with salicylaldehyde in situ in the presence of divalent metal salts in ethanolic medium. The complexes were characterized by elemental analyses, conductance, and magnetic measurements, as well as by IR and UV-Vis spectroscopy. The low values of the molar conductance indicate nonelectrolyte type of complexes. Based on spectral data and magnetic moments, an octahedral geometry may be proposed for Co(II, Ni(II, and Zn(II complexes while a tetragonal geometry for Cu(II complex. Molecular structure of the Schiff base ligand and its complexes were studied using programs dedicated to chemical modeling and quantomolecular calculation of chemical properties. All the synthesized complexes were tested for in vitro antibacterial activity against some pathogenic bacterial strains, namely Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. The MIC values shown by the complexes against these bacterial strains revealed that the metal complexes possess superior antibacterial activity than the Schiff base.

  8. Environmental effects on the structure of metal ion-DOTA complexes: An ab initio study of radiopharmaceutical metals.

    Energy Technology Data Exchange (ETDEWEB)

    Lau, E Y; Lightstone, F C; Colvin, M E

    2006-02-10

    Quantum mechanical calculations were performed to study the differences between the important radiopharmaceutical metals yttrium (Y) and indium (In) bound by DOTA and modified DOTA molecules. Energies were calculated at the MP2/6-31+G(d)//HF/6-31G(d) levels, using effective core potentials on the Y and In ions. Although the minimum energy structures obtained are similar for both metal ion-DOTA complexes, changes in coordination and local environment significantly affect the geometries and energies of these complexes. Coordination by a single water molecule causes a change in the coordination number and a change in the position of the metal ion in In-DOTA; but, Y-DOTA is hardly affected by water coordination. When one of the DOTA carboxylates is replaced by an amide, the coordination energy for the amide arm shows a large variation between the Y and In ions. Optimizations including water and guandinium moieties to approximate the effects of antibody binding indicate a large energy cost for the DOTA-chelated In to adopt the ideal conformation for antibody binding.

  9. Resonance raman spectra and photochemical reactivity of transition metal α-diimine complexes

    Science.gov (United States)

    Stufkens, D. J.

    In this article the application of resonance Raman spectroscopy to the study of metal to ligand charge transfer (MLCT) transitions of α-diimine complexes is described. From these spectra information is obtained about the character of the MLCT transitions and about the properties of the excited states. It is shown how these resonance Raman spectra can be used to interpret and predict the MLCT photo-chemistry of α-diimine and imine complexes.

  10. Investigation of complexing ability of ionites with various groups to some heavy and transition metal ions

    Directory of Open Access Journals (Sweden)

    Yedil Yergozhin

    2013-05-01

    Full Text Available The physico-chemical and complexing properties of the sorbent based on chloromethylated styrene and divinylbenzene copolymer with nicotinamide groups and copolymers based on metacryloilaminobenzene acids with 2-methyl-5-vinylpyridineisomers are studied. By potentiometric titration method the constant of polyelectrolytes functional groups ionization, the composition and strength of the resulting complexes with ions of some heavy and transition metals are determined.

  11. Metal complexation inhibits the effect of oxalic acid in aerosols as cloud condensation nuclei (CCN

    Directory of Open Access Journals (Sweden)

    T. Furukawa

    2010-11-01

    Full Text Available Atmospheric aerosols have both a direct and an indirect cooling effect that influences the radiative balance at the Earth's surface. It has been estimated that the degree of cooling is large enough to cancel the warming effect of carbon dioxide. Among the cooling factors, secondary organic aerosols (SOA play a key role in the solar radiation balance in the troposphere as SOA can act as cloud condensation nuclei (CCN and extend the lifespan of clouds because of their high hygroscopic and water soluble nature. Oxalic acid is one of the major components of SOA, and is produced via several formation pathways in the atmosphere. However, it is not certain whether oxalic acid exists as free oxalic acid or as metal oxalate complexes in aerosols, although there is a marked difference in their solubility in water and their hygroscopicity. We employed X-ray absorption fine structure spectroscopy to characterize the calcium (Ca and zinc (Zn in aerosols collected at Tsukuba in Japan with fractionation based on particle size using an impactor aerosol sampler. It was shown that 10–60% and 20–100% of the total Ca and Zn in the finer particles (<2.1 μm were present as Ca and Zn oxalate complexes, respectively. Oxalic acid can act as CCN because of its hygroscopic properties, while metal complexes are not hygroscopic, and so cannot be CCN. Based on the concentration of noncomplexed and metal-complexed oxalate species, we found that most of the oxalic acid is present as metal oxalate complexes in the aerosols, suggesting that oxalic acid does not act as CCN in the atmosphere. Similar results are expected for other dicarboxylic acids, such as malonic and succinic acids. Thus, it is possible that the cooling effect of organic aerosols assumed in various climate modeling studies is overestimated because of the lack of information on metal oxalate complexes in aerosols.

  12. Quantifying Pb and Cd complexation by alginates and the role of metal binding on macromolecular aggregation.

    Science.gov (United States)

    Lamelas, Cristina; Avaltroni, Fabrice; Benedetti, Marc; Wilkinson, Kevin J; Slaveykova, Vera I

    2005-01-01

    The Pb and Cd binding capacity of alginates were quantified by the determination of their complex stability constants and the concentration of complexing sites using H+, Pb2+, or Cd2+ selective electrodes in both static and dynamic titrations. Centrifugation filter devices (30 kDa filter cutoff), followed by inductively coupled plasma mass spectrometry (ICP-MS) measurements of lead or cadmium in the filtrates, were used to validate the results. The influence of ionic strength, pH, and the metal-to-alginate ratio was determined for a wide range of metal concentrations. Because of their polyelectrolytic properties, alginates may adopt different conformations depending on the physicochemistry of the medium, including the presence of metals. Therefore, molecular diffusion coefficients of the alginate were determined by fluorescence correlation spectroscopy under the same conditions of pH, ionic strength, and metal-to-alginate ratios that were used for the metal binding studies. The complexation and conformational properties of the alginate were related within the framework of the nonideal competitive adsorption isotherm (NICA) combined with a Donnan approach to account for both intrinsic and electrostatic contributions.

  13. Ultrafast Transient Absorption Spectroscopy of Polymer-Based Organophotoredox Catalysts Mimicking Transition-Metal Complexes

    Science.gov (United States)

    Jamhawi, Abdelqader; Paul, Anam C.; Smith, Justin D.; Handa, Sachin; Liu, Jinjun

    2017-06-01

    Transition-metal complexes of rare earth metals including ruthenium and iridium are most commonly employed as visible-light photocatalysts. Despite their highly important and broad applications, they have many disadvantages including high cost associated with low abundance in earth crust, potential toxicity, requirement of specialized ligands for desired activity, and difficulty in recycling of metal contents as well as associated ligands. Polymer-based organophotoredox catalysts are promising alternatives and possess unique advantages such as easier synthesis from inexpensive starting material, longer excited state life time, broad range of activity, sustainability, and recyclability. In this research talk, time-resolved photoluminescence and femtosecond transient absorption (TA) spectroscopy measurements of three novel polymer-based organophotoredox catalysts will be presented. By our synthetic team, their catalytic activity has been proven in some highly valuable chemical transformations, that otherwise require transition metal complexes. Time-resolved spectroscopic investigations have demonstrated that photoinduced processes in these catalysts are similar to the transition metal complexes. Especially, intramolecular vibrational relaxation, internal conversion, and intersystem crossing from the S1 state to the T1 state all occur on a sub-picosecond timescale. The long lifetime of the T1 state ( 2-3 microsecond) renders these polymers potent oxidizing and reducing agents. A spectroscopic and kinetic model has been developed for global fitting of TA spectra in both the frequency and time domains. Implication of the current ultrafast spectroscopy studies of these novel molecules to their roles in photocatalysis will be discussed.

  14. True boundary for the formation of homoleptic transition-metal hydride complexes.

    Science.gov (United States)

    Takagi, Shigeyuki; Iijima, Yuki; Sato, Toyoto; Saitoh, Hiroyuki; Ikeda, Kazutaka; Otomo, Toshiya; Miwa, Kazutoshi; Ikeshoji, Tamio; Aoki, Katsutoshi; Orimo, Shin-ichi

    2015-05-04

    Despite many exploratory studies over the past several decades, the presently known transition metals that form homoleptic transition-metal hydride complexes are limited to the Groups 7-12. Here we present evidence for the formation of Mg3 CrH8 , containing the first Group 6 hydride complex [CrH7 ](5-) . Our theoretical calculations reveal that pentagonal-bipyramidal H coordination allows the formation of σ-bonds between H and Cr. The results are strongly supported by neutron diffraction and IR spectroscopic measurements. Given that the Group 3-5 elements favor ionic/metallic bonding with H, along with the current results, the true boundary for the formation of homoleptic transition-metal hydride complexes should be between Group 5 and 6. As the H coordination number generally tends to increase with decreasing atomic number of transition metals, the revised boundary suggests high potential for further discovery of hydrogen-rich materials that are of both technological and fundamental interest.

  15. Matrix infrared spectra and density functional calculations of transition metal hydrides and dihydrogen complexes.

    Science.gov (United States)

    Andrews, Lester

    2004-02-20

    Metal hydrides are of considerable importance in chemical synthesis as intermediates in catalytic hydrogenation reactions. Transition metal atoms react with dihydrogen to produce metal dihydrides or dihydrogen complexes and these may be trapped in solid matrix samples for infrared spectroscopic study. The MH(2) or M(H(2)) molecules so formed react further to form higher MH(4), (H(2))MH(2), or M(H(2))(2), and MH(6), (H(2))(2)MH(2), or M(H(2))(3) hydrides or complexes depending on the metal. In this critical review these transition metal and dihydrogen reaction products are surveyed for Groups 3 though 12 and the contrasting behaviour in Groups 6 and 10 is discussed. Minimum energy structures and vibrational frequencies predicted by Density Functional Theory agree with the experimental results, strongly supporting the identification of novel binary transition metal hydride species, which the matrix-isolation method is well-suited to investigate. 104 references are cited.

  16. Microwave synthesis, spectral, thermal, and antimicrobial activities of some transition metal complexes involving 5-bromosalicylaldehyde moiety

    Directory of Open Access Journals (Sweden)

    Rajendra K. Jain

    2012-07-01

    Full Text Available The coordination complexes of Co(II, Ni(II and Cu(II derived from 5-bromosalicylidene-3,4-dimethylaniline (BSMA and 5-bromosalicylidene-3,4-dichloroaniline (BSCA have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, FT-IR, molar conductance, electronic spectra, 1H-NMR, FAB-mass, ESR, magnetic susceptibility, electrical conductivity and thermal analysis. The complexes are coloured and stable in air. Analytical data revealed that all the complexes exhibited 1:2 (metal: ligand ratio with coordination number 4 or 6. IR data shows that the ligand coordinates with the metal ions in a bidentate manner through the phenolic oxygen and azomethine nitrogen. FAB-mass and thermal data show degradation pattern of the complexes. Solid state electrical conductivity studies reflect semiconducting nature of the complexes. The Schiff base and metal complexes show a good activity against the Gram-positive bacteria; Staphylococcus aureus and Gram-negative bacteria; Escherichia coli and fungi Aspergillus niger and Candida albicans.

  17. Coordination diversity of new mononucleating hydrazone in 3d metal complexes: Synthesis, characterization and structural studies

    Directory of Open Access Journals (Sweden)

    RAJESH S. BALIGAR

    2006-12-01

    Full Text Available The mononucleating hydrazone ligand LH3, a condensation product of salicyloylhydrazine and (2-formylphenoxyacetic acid, was synthesized and its coordination behavior with first row transition metal(II ions was investigated by isolating and elucidating the structure of the complexes using elemental analysis, conductivity and magnetic susceptibility measurements, as well as IR, 1H-NMR, electronic and EPR spectral techniques. The ligand forms mononuclear metal(II complexes of the type [CoLH(H2O2], [NiLH(H2O2, [CuLH] and [ZnLH]. The ligand field parameters, Dq, B and b values, in the case of the cobalt and nickel complexes support not only the octahedral geometry around the metal ion, but also imply the covalent nature of the bonding in the complexes. The EPR study revealed the presence of a spin exchange interaction in the solid copper complex and the covalent nature of the bonding. The 1H-NMR study of the zinc(II complex indicated the non-involvement of the COOH group in the coordination. The physico-chemical study supports for the presence of octahedral geometry around cobalt(II, nickel(II and tetrahedral geometry around copper(II and zinc(II ions.

  18. A review on versatile applications of transition metal complexes incorporating Schiff bases

    Directory of Open Access Journals (Sweden)

    Ahmed M. Abu-Dief

    2015-06-01

    Full Text Available Schiff bases and their complexes are versatile compounds synthesized from the condensation of an amino compound with carbonyl compounds and widely used for industrial purposes and also exhibit a broad range of biological activities including antifungal, antibacterial, antimalarial, antiproliferative, anti-inflammatory, antiviral, and antipyretic properties. Many Schiff base complexes show excellent catalytic activity in various reactions and in the presence of moisture. Over the past few years, there have been many reports on their applications in homogeneous and heterogeneous catalysis. The high thermal and moisture stabilities of many Schiff base complexes were useful attributes for their application as catalysts in reactions involving at high temperatures. The activity is usually increased by complexation therefore to understand the properties of both ligands and metal can lead to the synthesis of highly active compounds. The influence of certain metals on the biological activity of these compounds and their intrinsic chemical interest as multidentate ligands has prompted a considerable increase in the study of their coordination behaviour. Development of a new chemotherapeutic Schiff bases and their metal complexes is now attracting the attention of medicinal chemists. This review compiles examples of the most promising applied Schiff bases and their complexes in different areas.

  19. Application of the hybrid complexation-ultrafiltration process for metal ion removal from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Zeng Jianxian [College of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China) and College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)], E-mail: zengjianxian@163.com; Ye Hongqi [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Hu Zhongyu [College of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China)

    2009-01-30

    Complexation-ultrafiltration process was investigated for mercury and cadmium removal from aqueous solutions by using poly(acrylic acid) sodium salt (PAASS) as a complexing agent. The kinetics of complexation reactions of PAASS with the metal ions were studied under a large excess PAASS and pH 5.5. It takes 25 and 50 min for mercury and cadmium to get the complexation equilibrium, respectively, and the reaction kinetics can be described by a pseudo-first-order equation. Effects of various operating parameters such as loading ratios, pH values, etc. on metal rejection coefficients (R) were investigated. In the process of concentration, membrane fluxes decline slowly and R values are about 1. The concentrated retentates were used further for the decomplexation. The decomplexation ratio of mercury-PAASS complex is about 30%, whereas that of cadmium-PAASS complex reaches 93.5%. After the decomplexation, diafiltration experiments were carried out at pH 2.5. Cadmium can be diafiltrated satisfactorily from the retentate, but for mercury it is the contrary. Selective separation of the both metal ions was studied from a binary solution at pH 5. When mercury, cadmium and PAASS concentrations are 30, 30 and 40 mg L{sup -1}, respectively, mercury is retained by ultrafiltration while almost all cadmium passes through the membrane.

  20. Application of the hybrid complexation-ultrafiltration process for metal ion removal from aqueous solutions.

    Science.gov (United States)

    Zeng, Jianxian; Ye, Hongqi; Hu, Zhongyu

    2009-01-30

    Complexation-ultrafiltration process was investigated for mercury and cadmium removal from aqueous solutions by using poly(acrylic acid) sodium salt (PAASS) as a complexing agent. The kinetics of complexation reactions of PAASS with the metal ions were studied under a large excess PAASS and pH 5.5. It takes 25 and 50 min for mercury and cadmium to get the complexation equilibrium, respectively, and the reaction kinetics can be described by a pseudo-first-order equation. Effects of various operating parameters such as loading ratios, pH values, etc. on metal rejection coefficients (R) were investigated. In the process of concentration, membrane fluxes decline slowly and R values are about 1. The concentrated retentates were used further for the decomplexation. The decomplexation ratio of mercury-PAASS complex is about 30%, whereas that of cadmium-PAASS complex reaches 93.5%. After the decomplexation, diafiltration experiments were carried out at pH 2.5. Cadmium can be diafiltrated satisfactorily from the retentate, but for mercury it is the contrary. Selective separation of the both metal ions was studied from a binary solution at pH 5. When mercury, cadmium and PAASS concentrations are 30, 30 and 40 mg L(-1), respectively, mercury is retained by ultrafiltration while almost all cadmium passes through the membrane.

  1. Effects of Ti-bearing inclusions on the microstructure and mechanical properties of MAG multilayer weld metal

    Institute of Scientific and Technical Information of China (English)

    Xin WANG; Wenchao DONG; Shanping LU; Guangzhong HE; Xu ZHAO; Dianmai ZHOU; Yiyi LI

    2012-01-01

    The metal active gas (MAG) multilayer weld metal consists of the columnar grain zone (CGZ) and the fine grain zone (FGZ).Mechanical properties and microstructure of the CGZ and FGZ have been analyzed and evaluated.The inclusion with a size of 0.2-1.0 μm is typical log-normal distribution.The morphology of inclusions has been analyzed using transmission electron microscope (TEM).With the microalloying element Ti addition,much MnTiO3 phase precipitates on the Mn-silicates matrix,which is beneficial for the nucleation of acicular ferrite (AF).The probable mechanism for the nucleation of AF has been discussed.

  2. Ruthenium(II) complexes bearing pyridine-functionalized N-heterocyclic carbene ligands: Synthesis, structure and catalytic application over amide synthesis

    Indian Academy of Sciences (India)

    MUTHUKUMARAN NIRMALA; PERIASAMY VISWANATHAMURTHI

    2016-11-01

    A series of four imidazolium salts was synthesized by the reaction of 2-bromopyridine with 1- substituted imidazoles. These imidazolium salts (1a–d) were successfully employed as ligand precursors for the syntheses of new ruthenium(II) complexes bearing neutral bidentate ligands of N-heterocyclic carbene and pyridine donor moiety. The NHC-ruthenium(II) complexes (3a–d) were synthesized by reacting the appropriately substituted pyridine-functionalized N-heterocyclic carbenes with Ag₂O forming the NHC–silver bromide in situ followed by transmetalation with [RuHCl(CO)(PPh₃)₃]. The new complexes were characterized by elemental analyses and spectroscopy (IR, UV-Vis, ¹H, ¹³C, ³¹P-NMR) as well as ESI mass spectrometry. Based on the spectral results, an octahedral geometry was assigned for all the complexes. The complexes were shown to be efficient catalysts for the one-pot conversion of various aldehydes to their corresponding primary amides with good to excellent isolated yields using NH₂OH.HCl and NaHCO₃. The effects of solvent, base, temperature, time and catalyst loading were also investigated. A broad range of amides were successfully synthesized with excellent isolated yields using the above optimized protocol. Notably, the complex 3a was found to be a very efficient and versatile catalyst towards amidation of a wide range of aldehydes.

  3. Cationic schiff base amphiphiles and their metal complexes: Surface and biocidal activities against bacteria and fungi.

    Science.gov (United States)

    Negm, N A; Zaki, M F; Salem, M A I

    2010-05-01

    A series of cationic surfactants containing schiff base groups was synthesized by condensation of four fatty amines namely: dodecyl, tetradecyl, hexadecyl and octadecyl amine and 4-diethyl aminobenzaldehyde (1-4), as well as their metal complexes with divalent transition metal ions including Co, Cu and Mn (5-16). The surface activities of the synthesized surfactants were influenced by their chemical structures and the type of the transition metals. The biological activity measurements of the parent cationic schiff bases showed high efficacy against Gram positive and Gram negative bacterial strains and fungi. While on complexation, the biocidal activity was increased remarkably. The biocidal activity of the tested compounds against sulfur reducing bacteria showed promising results in the field of biocide applications.

  4. Polarographic Determination of Composition and Thermodynamic Stability Constant of a Complex Metal Ion.

    Science.gov (United States)

    Marin, Dolores; Mendicuti, Francisco

    1988-01-01

    Describes a laboratory experiment designed to encourage laboratory cooperation among individual undergraduate students or groups. Notes each student contributes results individually and the exchange of data is essential to obtain final results. Uses the polarographic method for determining complex metal ions. (MVL)

  5. Synthesis and antimicrobial activity of polysaccharide alginate derived cationic surfactant-metal(II) complexes.

    Science.gov (United States)

    Tawfik, Salah M; Hefni, Hassan H

    2016-01-01

    New natural polysaccharide carbohydrate derivatives of sodium alginate surfactant and its cobalt, copper and zinc complexes were synthesized. Structures of the synthesized compounds are reported using FTIR, (1)H NMR and UV-vis. The critical micelle concentration (CMC) value of the alginate surfactant and its metal complexes in aqueous solution was found out from surface tension measurements. Surface tension data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔGmic, ΔHmic, ΔSmic) and adsorption (ΔGads, ΔGads, ΔSads). The surface activities of the synthesized polymeric surfactant and its metal complexes were influenced by their chemical structures and the type of the transition metals. These compounds were evaluated against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Candida albicans and Asperigllus niger). The antibacterial and antifungal screening tests of the alginate surfactant metal complexes have shown good results compared to its precursor alginate surfactant.

  6. Quantum Mechanics Calculations, Basicity and Crystal Structure: The Route to Transition Metal Complexes of Azahelicenes

    Directory of Open Access Journals (Sweden)

    Isabella Natali Sora

    2012-01-01

    Full Text Available Quantum mechanics density functional calculations provided gas-phase electron distributions and proton affinities for several mono- and diaza[5]helicenes; computational results, together with experimental data concerning crystal structures and propensity to methylation of the nitrogen atom(s, provide a basis for designing azahelicene complexes with transition metal ions.

  7. Multiheteromacrocycles that Complex Metal Ions. Fourth Progress Report, 1 May 1977 -- 30 April 1978

    Science.gov (United States)

    Cram, D. J.

    1978-01-15

    Results are reported in a program to design, synthesize, and evaluate polycyclic host organic compounds for their abilities to complex and lipophilize guest metal ions. Work during the reporting period was devoted to synthesis and study of cyclohexametaphenylenes and cyclic phosphine oxides. (JRD)

  8. Metal Ion Complexes with HisGly: Comparison with PhePhe and PheGly

    NARCIS (Netherlands)

    Dunbar, R.C.; Oomens, J.; Berden, G.; Lau, J.K.C.; Verkerk, U.H.; Hopkinson, A.C.; Siu, K.W.M.

    2013-01-01

    Gas-phase complexes of five metal ions with the dipeptide HisGly have been characterized by DFT computations and by infrared multiple photon dissociation spectroscopy (IRMPD) using the free electron laser FELIX. Fine agreement is found in all five cases between the predicted IR spectral features of

  9. Synthesis and Structural Characterization of Schiff Base Ligand and their Metal Complexes

    Directory of Open Access Journals (Sweden)

    Amit Kumar Gautam

    2016-05-01

    Full Text Available In the present work, the synthesis and structural characterization of a 2-phenyl- 3(benzamido propyl quinazoline (3H -4- one semicarbazone/ thiosemicarbazone hydrochloride and its metal complexes have been reported. All the synthesized compounds were characterized by using various physico-chemical techniques such as Infrared spectra, electronic spectra, molar conductivity and magnetic susceptibility measurements. The ligand and metal ions reacted to form in the 2:1 ratio as found from the elemental analyses and general stiochiometry was determined, [M(PBPQS2X2] and [M(PBPQT2X2]; where M = Co(II, Ni(II and Cu(II; PBPQS = 2-phenyl- 3 (benzamido propyl quinazoline (3H -4- one semicarbazone and PBPQT = 2- phenyl- 3 (benzamido propyl quinazoline (3H -4- one thiosemicarbazone. On the basis of analytical data, a proposed structure for the Cu(II complexes are distorted octahedral and those for Co(II and Ni(II complexes are octahedral. Ligands PBPQS/ PBPQT have been proposed to act in a bidentate manner co-ordinating to the metal ions though azomethine nitrogen and oxygen/ sulphur atom of either semicarbazone/ thiosemicarbazone moiety. The remaining co-ordination sites are occupied by negative ions such as Cl-, Br-, I- or NO3-. The ligands and its metal complexes were tested for their possible antimicrobial potentials.

  10. Group 4 Transition-Metal Complexes of an Aniline–Carbene–Phenol Ligand

    KAUST Repository

    Despagnet-Ayoub, Emmanuelle

    2013-05-24

    Attempts to install a tridentate aniline-NHC-phenol (NCO) ligand on titanium and zirconium led instead to complexes resulting from unexpected rearrangement pathways that illustrate common behavior in carbene-early- transition-metal chemistry. © 2013 American Chemical Society.

  11. Design, spectral characterization and biological studies of transition metal(II) complexes with triazole Schiff bases

    Science.gov (United States)

    Hanif, Muhammad; Chohan, Zahid H.

    2013-03-01

    A new series of three biologically active triazole derived Schiff base ligands L1-L3 have been synthesized in equimolar reaction of 3-amino-1H-1,2,4-triazole with pyrrol-2-carboxaldehyde, 4-bromo-thiophene-2-carboxaldehyde, and 5-iodo-2-hydroxy benzaldehyde. The prepared Schiff bases were used for further complex formation reaction with different metal elements like Co(II), Ni(II), Cu(II) and Zn(II) as chlorides by using a molar ratio of ligand:metal as 2:1. The structure and bonding nature of all the compounds were identified by their physical, spectral and analytical data. All the metal(II) complexes possessed an octahedral geometry except the Cu(II) complexes which showed a distorted octahedral geometry. All the synthesized compounds, were studied for their in vitro antibacterial, and antifungal activities, against four Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and against six fungal strains (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata) by using agar-well diffusion method. It has been shown that all the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. In vitro Brine Shrimp bioassay was also carried out to investigate the cytotoxic properties of these compounds. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination.

  12. Design, spectral characterization and biological studies of transition metal(II) complexes with triazole Schiff bases.

    Science.gov (United States)

    Hanif, Muhammad; Chohan, Zahid H

    2013-03-01

    A new series of three biologically active triazole derived Schiff base ligands L(1)-L(3) have been synthesized in equimolar reaction of 3-amino-1H-1,2,4-triazole with pyrrol-2-carboxaldehyde, 4-bromo-thiophene-2-carboxaldehyde, and 5-iodo-2-hydroxy benzaldehyde. The prepared Schiff bases were used for further complex formation reaction with different metal elements like Co(II), Ni(II), Cu(II) and Zn(II) as chlorides by using a molar ratio of ligand:metal as 2:1. The structure and bonding nature of all the compounds were identified by their physical, spectral and analytical data. All the metal(II) complexes possessed an octahedral geometry except the Cu(II) complexes which showed a distorted octahedral geometry. All the synthesized compounds, were studied for their in vitro antibacterial, and antifungal activities, against four Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and against six fungal strains (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata) by using agar-well diffusion method. It has been shown that all the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. In vitro Brine Shrimp bioassay was also carried out to investigate the cytotoxic properties of these compounds. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination.

  13. Spectroscopic studies and biological activity of some transition metal complexes of unusual Schiff base

    Science.gov (United States)

    Abu Al-Nasr, Ahmad K.; Ramadan, Ramadan M.

    2013-03-01

    Unusual Schiff base ligand, 4-ethanimidoyl-6-[(1E)-N-(2-hydroxy-4-methylphenyl)ethanimidoyl]benzene-1,3-diol, L, was synthesized via catalytic process involving the interaction of some metal ions with a macrocyclic Schiff base (MSB). The transition metal derivatives [ML(H2O)4](NO3)3, M = Cr(III) and Fe(III), [NiL(H2O)4](NO3)2, [ML(H2O)2](NO3)2, M = Zn(II) and Cd(II), [Cl2Pd(μ-Cl)2PdL], [PtL(Cl)2] and [PtL(Cl)4] were also synthesized from the corresponding metal species with L. The Schiff bases and complexes were characterized by elemental analysis, mass spectrometry, IR and 1H NMR spectroscopy. The crystal structure of L was determined by X-ray analysis. The spectroscopic studies revealed a variety of structure arrangements for the complexes. The biological activities of L and metal complexes against the Escherchia coli as Gram-negative bacteria and Staphylococcus aureus as Gram-positive bacteria, and the two fungus Aspergillus flavus and Candida albicans were screened. The cytotoxicity of [PtL(Cl)2] complex, a cis-platin analogous, was checked as an antitumor agent on two breast cancer cell lines (MCF7 and T47D) and human liver carcinoma cell line (HepG2).

  14. Methodology development for the sustainability process assessment of sheet metal forming of complex-shaped products

    Science.gov (United States)

    Pankratov, D. L.; Kashapova, L. R.

    2015-06-01

    A methodology was developed for automated assessment of the reliability of the process of sheet metal forming process to reduce the defects in complex components manufacture. The article identifies the range of allowable values of the stamp parameters to obtain defect-free punching of spars trucks.

  15. Characterization of tannin-metal complexes by UV-visible spectrophotometry

    Science.gov (United States)

    Tannins enter soils by plant decay and rain throughfall, but little is known of their effects on soils. Tannins may influence bioavailability and toxicity of metals by forming complexes and by mediating redox reactions. We evaluated the affinity and stoichiometry of Al(III) for a gallotannin, pent...

  16. Metal Cation Binding to Gas-Phase Pentaalanine: Divalent Ions Restructure the Complex

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Polfer, N. C.; Oomens, J.

    2013-01-01

    Ion-neutral complexes of pentaalalanine with several singly- and doubly charged metal ions are examined using conformation analysis by infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) computations. The infrared spectroscopy in the 1500-1800 cm(-1) region

  17. [Electron spectra of chemical assembly mesoporous MCM-41 with transition metal complexes].

    Science.gov (United States)

    Huo, Yong-qian; Li, Jun; Wang, Wei; Gong, Ya-qiong; Zhang, Feng-xing

    2004-03-01

    In the paper the complexes of metal cobalt(III), manganese(III), iron(III) and copper(II) with Schiff-base N,N-ethylenebis(salicylideneaminnato) have been synthesized and characterized. The nanosized porous material MCM-41 has been functionalized by the modification of the internal pore surface with gamma-aminopropyl and was assembled by the modification groups with metal complex of Schiff-base. These metal complexes and functionalized nanosized porous materials were charcterized by XRD, IR and UV-Vis. It is indicated by spectral analysis that the synthesized nanosized porous materials have been confirmed to be MCM-41 with hexagon bores, and the gamma-aminopropyls have been bonded on their internal pore surface. And the complexes of metal cobalt(III), manganese(III), iron(III) and copper(II) with Schiff-base N,N-ethylenebis(salicylideneaminnato) were assembled into MCM-41. The IR spectra of these samples show that there were characteristic absorptions of the amino and the Schiff base groups, and the absorption of amino shifted to longer wavelength.

  18. Direct observation of surface reconstruction and termination on a complex metal oxide catalyst by electron microscopy

    KAUST Repository

    Zhu, Yihan

    2012-03-19

    On the surface: The surface reconstruction of an MoVTeO complex metal oxide catalyst was observed directly by various electron microscopic techniques and the results explain the puzzling catalytic behavior. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Designing metal hydride complexes for water splitting reactions: a molecular electrostatic potential approach.

    Science.gov (United States)

    Sandhya, K S; Suresh, Cherumuttathu H

    2014-08-28

    The hydridic character of octahedral metal hydride complexes of groups VI, VII and VIII has been systematically studied using molecular electrostatic potential (MESP) topography. The absolute minimum of MESP at the hydride ligand (Vmin) and the MESP value at the hydride nucleus (VH) are found to be very good measures of the hydridic character of the hydride ligand. The increasing/decreasing electron donating feature of the ligand environment is clearly reflected in the increasing/decreasing negative character of Vmin and VH. The formation of an outer sphere metal hydride-water complex showing the HH dihydrogen interaction is supported by the location and the value of Vmin near the hydride ligand. A higher negative MESP suggested lower activation energy for H2 elimination. Thus, MESP features provided a way to fine-tune the ligand environment of a metal-hydride complex to achieve high hydridicity for the hydride ligand. The applicability of an MESP based hydridic descriptor in designing water splitting reactions is tested for group VI metal hydride model complexes of tungsten.

  20. Metal Cation Binding to Gas-Phase Pentaalanine: Divalent Ions Restructure the Complex

    NARCIS (Netherlands)

    Dunbar, R.C.; Steill, J.D.; Polfer, N.C.; Oomens, J.

    2013-01-01

    Ion-neutral complexes of pentaalalanine with several singly- and doubly charged metal ions are examined using conformation analysis by infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) computations. The infrared spectroscopy in the 1500-1800 cm(-1) region

  1. Effective DNA binding and cleaving tendencies of malonic acid coupled transition metal complexes

    Science.gov (United States)

    Pravin, Narayanaperumal; Utthra, Ponnukalai Ponya; Kumaravel, Ganesan; Raman, Natarajan

    2016-11-01

    Eight transition metal complexes were designed to achieve maximum biological efficacy. They were characterized by elemental analysis and various other spectroscopic techniques. The monomeric complexes were found to espouse octahedral geometry and non-electrolytic nature. The DNA interaction propensity of the complexes with calf thymus DNA (CT-DNA), studied at physiological pH by spectrophotometric, spectrofluorometric, cyclic voltammetry, and viscometric techniques revealed intercalation as the possible binding mode. Fascinatingly, the complexes were found to exhibit greater binding strength than that of the free ligands. A strong hypochromism and a slight red shift were exhibited by complex 5 among the other complexes. The intrinsic binding constant values of all the complexes compared to cisplatin reveal that they are excellent metallonucleases than that of cisplatin. The complexes were also shown to reveal displacement of the ethidium bromide, a strong intercalator using fluorescence titrations. Gel electrophoresis was used to divulge the competence of the complexes in cleaving the supercoiled pBR322 plasmid DNA. From the results, it is concluded that the complexes, especially 5, are excellent chemical nucleases in the presence of H2O2. Furthermore, the in vitro antimicrobial screening of the complexes exposes that these complexes are excellent antimicrobial agents. Overall the effect of coligands is evident from the results of all the investigations.

  2. Site-selective electroless nickel plating on patterned thin films of macromolecular metal complexes.

    Science.gov (United States)

    Kimura, Mutsumi; Yamagiwa, Hiroki; Asakawa, Daisuke; Noguchi, Makoto; Kurashina, Tadashi; Fukawa, Tadashi; Shirai, Hirofusa

    2010-12-01

    We demonstrate a simple route to depositing nickel layer patterns using photocross-linked polymer thin films containing palladium catalysts, which can be used as adhesive interlayers for fabrication of nickel patterns on glass and plastic substrates. Electroless nickel patterns can be obtained in three steps: (i) the pattern formation of partially quaterized poly(vinyl pyridine) by UV irradiation, (ii) the formation of macromolecular metal complex with palladium, and (iii) the nickel metallization using electroless plating bath. Metallization is site-selective and allows for a high resolution. And the resulting nickel layered structure shows good adhesion with glass and plastic substrates. The direct patterning of metallic layers onto insulating substrates indicates a great potential for fabricating micro/nano devices.

  3. Electronic structures and magnetic/optical properties of metal phthalocyanine complexes

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Shintaro; Suzuki, Atsushi, E-mail: suzuki@mat.usp.ac.jp; Oku, Takeo [Department of Materials Science, The University of Shiga Prefecture. 2500 Hassaka, Hikone, Shiga 522-8533 (Japan)

    2016-02-01

    Electronic structures and magnetic / optical properties of metal phthalocyanine complexes were studied by quantum calculations using density functional theory. Effects of central metal and expansion of π orbital on aromatic ring as conjugation system on the electronic structures, magnetic, optical properties and vibration modes of infrared and Raman spectra of metal phthalocyanines were investigated. Electron and charge density distribution and energy levels near frontier orbital and excited states were influenced by the deformed structures varied with central metal and charge. The magnetic parameters of chemical shifts in {sup 13}C-nuclear magnetic resonance ({sup 13}C-NMR), principle g-tensor, A-tensor, V-tensor of electric field gradient and asymmetry parameters derived from the deformed structures with magnetic interaction of nuclear quadruple interaction based on electron and charge density distribution with a bias of charge near ligand under crystal field.

  4. Covalent heterogenization of discrete bis(8-quinolinolato)dioxomolybdenum(VI) and dioxotungsten(VI) complexes by a metal-template/metal-exchange method: Cyclooctene epoxidation catalysts with enhanced performances

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying; Chattopadhyay, Soma; Shibata, Tomohiro; Ren, Yang; Lee, Sungsik; Kan, Qiubin

    2014-10-01

    A metal-template/metal-exchange method was used to imprint covalently attached bis(8- quinolinolato)dioxomolybdenum(VI) and dioxotungsten(VI) complexes onto large surface-area, mesoporous SBA-15 silica to obtain discrete MoO2 VIT and WO2 VIT catalysts bearing different metal loadings, respectively. Homogeneous counterparts, MoO2 VIN and WO2 VIN, as well as randomly ligandgrafted heterogeneous analogues, MoO2 VIG and WO2 VIG, were also prepared for comparison. X-ray absorption fine structure (XAFS), pair distribution function (PDF) and UV–vis data demonstrate that MoO2 VIT and WO2 VIT adopt a more solution-like bis(8-quinolinol) coordination environment than MoO2 VIG and WO2 VIG, respectively. Correspondingly, the templated MoVI and WVI catalysts show superior performances to their randomly grafted counterparts and neat analogues in the epoxidation of cyclooctene. It is found that the representative MoO2 VIT-10% catalyst can be recycled up to five times without significant loss of reactivity, and heterogeneity test confirms the high stability of MoO2 VIT-10% catalyst against leaching of active species into solution. The homogeneity of the discrete bis(8-quinolinol) metal spheres templated on SBA-15 should be responsible for the superior performances.

  5. Characterization of surfactant effects on the visible spectroscopy of lanthanide metal ion-triphenylmethane dye complexes

    Energy Technology Data Exchange (ETDEWEB)

    Klopf, G.J.

    1985-01-01

    To better define the mechanism responsible for sensitization, the interactions of representative cationic, anionic, and nonionic surfactants with several lanthanide metal ion-triphenylmethane dye complexes, particularly the gadolinium (Gd/sup +3/)-Chromeazurol S (CAS) complex, were characterized. Only cationic surfactants induced sensitization when added to the Gd/sup +3/-CAS complex. Sensitization induced by cetylpyridinium chloride (CPC) occurred at submicellar concentrations and was attributed to the formation of a 1:2:4 Gd/sup +3/-CAS-CPC ternary complex. Additional ternary complexes evidently form if excess CAS is present. Mechanisms are proposed for the sensitization of the reaction by quaternary compounds and by anionic surfactants. Although both micellar and submicellar concentrations were considered, adding the nonionic surfactant Triton X-100 to the Gd/sup +3/-CAS complex had little effect.

  6. Determination of complexation capacity of trace metal-organic in natural water

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The complexation capacity for heavy metals (Cu, Cd, Pb) were determined by anodic stripping voltammetry in South China Sea, Hulun Lake and Wuliang Suhai. The conditional stability constants and complexation capacity index were calculated. The data showed that the complexation capacity of the Hulun Lake was greater than that of seawater and Wuliang Suhai. The sequence of complexation capacity is C (CuL) > C (CdL) > C (PbL), the values are in concord with results of analysis on dissolved organic carbon. The conditional stability constants were in an opposite sequence: K (CuL) < K(CdL) < K (PbL). When logK are similar, the greater the complexation capacity, the greater the complexation capacity index.

  7. Precious metal enrichment at low-redox in terrestrial native Fe-bearing basalts investigated using laser-ablation ICP-MS

    Science.gov (United States)

    Howarth, Geoffrey H.; Day, James M. D.; Pernet-Fisher, John F.; Goodrich, Cyrena A.; Pearson, D. Graham; Luo, Yan; Ryabov, Viktor V.; Taylor, Lawrence A.

    2017-04-01

    Primary native Fe is a rare crystallizing phase from terrestrial basaltic magmas, requiring highly reducing conditions (fO2 group elements [PGE], Pd, Pt, Rh, Ru, Ir, Os), as well as Ni and Cu, to economic abundances. Three localities are known globally where native Fe bearing mafic rocks occur: (1) Paleocene basalts of Disko Island, West Greenland; (2) a Miocene lava of the Bühl basalts, Germany; and (3) mafic intrusions associated with the Late Permian Siberian flood basalts. In this contribution, we report major- and minor-element compositions and HSE concentrations for the main alloy phases (FeNi metal and cohenite) and sulfide, for all three known global occurrences of native Fe bearing basalt. Total HSE abundances in metal grains, obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), are lowest in the Bühl basalt, (∼0.05 ppm), intermediate in the Disko Island basalts (4-8 ppm), and highest the Siberian Khungtukun and Dzhaltul intrusions (10-30 ppm). These differences demonstrate that, while native Fe formation is the result of carbonaceous crustal assimilation, HSE enrichment is not ubiquitous during this process. The Siberian occurrences are characterized by Pt PGE (PPGE: Pt, Pd) enrichment relative to the Ir PGE (IPGE: Rh, Ru, Ir, Os), consistent with models of early stage fractionation of olivine, chromite and metallic IPGE in staging magma reservoirs, prior to the addition of C-rich crustal materials in the shallow crust. Relative to Noril'sk Ni-Cu-PGE sulfide ores, the Siberian native Fe basalts are enriched in the PPGE relative to the IPGE, but exhibit Ru enrichments. In contrast, Disko Island native Fe rocks do not show significant fractionation of the PPGE from the IPGE, but have positive Re and Ru anomalies and high Os/Ir ratios. To reconcile these observations, we present a general model where some parental melts experienced early-stage crustal assimilation in staging magma reservoirs, prior to reduction by carbon

  8. Anthracene-terpyridine metal complexes as new G-quadruplex DNA binders.

    Science.gov (United States)

    Gama, Sofia; Rodrigues, Inês; Mendes, Filipa; Santos, Isabel C; Gabano, Elisabetta; Klejevskaja, Beata; Gonzalez-Garcia, Jorge; Ravera, Mauro; Vilar, Ramon; Paulo, António

    2016-07-01

    The formation of quadruple-stranded DNA induced by planar metal complexes has particular interest in the development of novel anticancer drugs. This is especially relevant for the inhibition of telomerase, which plays an essential role in cancer cell immortalization and is overexpressed in ca. 85-90% of cancer cells. Moreover, G-quadruplexes also exist in other locations in the human genome, namely oncogene promoter regions, and it has been hypothesized that they play a regulatory role in gene transcription. Herein we report a series of new anthracene-containing terpyridine ligands and the corresponding Cu(II) and Pt(II) complexes, with different linkers between the anthracenyl moiety and the terpyridine chelating unit. The interaction of these ligands and metal complexes with different topologies of DNA was studied by several biophysical techniques. The Pt(II) and Cu(II) complexes tested showed affinity for quadruplex-forming sequences with a good selectivity over duplex DNA. Importantly, the free ligands do not have significant affinity for any of the DNA sequences used, which shows that the presence of the metal is essential for high affinity (and selectivity). This effect is more evident in the case of the Pt(II) complexes. Moreover, the presence of a longer linker between the chelating terpyridine unit and the anthracene moiety enhances the interaction with G-quadruplex-forming sequences. We further evaluated the ability of the Cu(II) complexes to interact with, and stabilize G-quadruplex containing regions in oncogene promoters via a polymerase stop assay. These studies indicated that the metal complexes are able to induce G-quadruplex formation and stop polymerase activity.

  9. Responsive metal complexes: a click-based "allosteric scorpionate" complex permits the detection of a biological recognition event by EPR/ENDOR spectroscopy.

    Science.gov (United States)

    Tamanini, Emiliano; Rigby, Stephen E J; Motevalli, Majid; Todd, Matthew H; Watkinson, Michael

    2009-01-01

    Chemical sensing is a mature field, and many effective sensors for small anions and cations have been devised. Metal complexes have been used widely for this purpose, but there are fewer reports of their use in the detection of organic and biological analytes. To date metal complexes have been used in sensing via the direct displacement of a pre-existing ligand by an analyte, or by an adventitious complementarity between the complex and analyte. These strategies do not permit a general approach to the sensing of biological molecules with metal complexes because of the demands to engineer molecular recognition into the complex architecture. We describe a fundamentally new approach to this field-the "allosteric scorpionate" metal complex. The binding partner of a biological analyte is attached to a scorpionate ligand on a metal complex, remote from the metal centre. Binding of the analyte causes a change in the primary coordination sphere at the metal, thereby revealing the presence of the biological molecule. We show that azamacrocyclic complexes with a triazole scorpion ligand may be easily assembled with the [3+2] Huisgens 'click' cycloaddition. We demonstrate the synthesis of a biotin-functionalised cyclam derivative using this methodology. This, and our previously communicated zinc sensor, are to the best of our knowledge the first examples of a triazole being employed as a scorpion ligand on an azamacrocycle. Coordination by the triazole to the metal is perturbed by the binding of avidin to the pendant ligand. This event can be sensitively detected with EPR spectroscopy, and the details of the coordination change probed with ENDOR spectroscopy, confirming the loss of the axial triazole nitrogen donor upon binding to avidin. This represents the first metal complex where remote, 'allosteric' coordination of an analyte has been shown to cause a change in the primary coordination sphere of the metal. Since the synthesis is modular and straightforward, other

  10. Grizzly bear

    Science.gov (United States)

    Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.

    2003-01-01

    The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

  11. Impact of ligand protonation on higher-order metal complexation kinetics in aqueous systems.

    Science.gov (United States)

    Town, Raewyn M; Leeuwen, Herman P van

    2008-03-27

    The impact of ligand protonation on the complexation kinetics of higher-order complexes is quantitatively described. The theory is formulated on the basis of the usual situation for metal complex formation in aqueous systems in which the exchange of water for the ligand in the inner coordination sphere is rate-determining (Eigen mechanism). We derive expressions for the general case of lability of ML(n) species that account for the contributions from all outer-sphere complexes to the rate of complex formation. For dynamic complexes, dissociation of ML is usually the rate-determining step in the overall process ML(n) --> M. Under such conditions, it is the role of ligand protonation in the step ML --> M that is relevant for the kinetic flux. 1:2 complexes of Cd(II) with pyridine-2,6-dicarboxylic acid fall into this category, and their lability at a microelectrode is reasonably well predicted by the differentiated approach. For non-dynamic systems, the kinetic flux arising from dissociation of higher-order complexes contributes to the rate-determining step. In this case, the weighted contribution of protonated and unprotonated outer-sphere complexes in all contributing dissociation reactions must be taken into account. The kinetic flux arising from the dissociation of 1:2 complexes of Ni(II) with bicine at a conventional electrode was quite well described by this combined approach. The results establish the generic role of ligand protonation within the overall framework of metal complexation kinetics in which complexes may be dynamic to an extent that depends on the operational time scale of the measurement technique.

  12. Synthesis of trimethoprim metal complexes: Spectral, electrochemical, thermal, DNA-binding and surface morphology studies.

    Science.gov (United States)

    Demirezen, Nihat; Tarınç, Derya; Polat, Duygu; Ceşme, Mustafa; Gölcü, Ayşegül; Tümer, Mehmet

    2012-08-01

    Complexes of trimethoprim (TMP), with Cu(II), Zn(II), Pt(II), Ru(III) and Fe(III) have been synthesized. Then, these complexes have been characterized by spectroscopic techniques involving UV-vis, IR, mass and (1)H NMR. CHN elemental analysis, electrochemical and thermal behavior of complexes have also been investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV spectroscopy and cyclic voltammetry. UV studies of the interaction of the complexes with DNA have shown that these compounds can bind to CT DNA. The binding constants of the complexes with CT DNA have also been calculated. The cyclic voltammograms of the complexes in the presence of CT DNA have shown that the complexes can bind to CT DNA by both the intercalative and the electrostatic binding mode. The antimicrobial activity of these complexes has been evaluated against three Gram-positive and four Gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with the reference drug TMP. Almost all types of complexes show excellent activity against all type of bacteria and fungi. The morphology of the CT DNA, TMP, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with CT DNA has been studied by means of differential pulse voltammetry (DPV) at CT DNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism.

  13. Synthesis, Characterization of Neutral Nickel Complexes Bearing N-Fluorophenylsalicylaldimine Chelate Ligands and Their Catalytic Activity to Ethylene Oligomerization

    Institute of Scientific and Technical Information of China (English)

    赵蔚; 黄吉玲; 朱仕正

    2005-01-01

    A series of neutral nickel complexes featuring N-fluorophenylsalicylaldimine chelate ligands was synthesized,and the molecular structure of complex 4 was further confirmed by X-ray crystallographic analysis. The neutral nickel complexes showed high activity up to 4.22×105 g oligomers/(mol Nioh) and high selectivity to C6 olefins in catalyzing ethylene oligomerization using methylaluminoxane (MAO) as cocatalyst.

  14. Synthesis, characterization, and reactivity of a side-on manganese(iii)-peroxo complex bearing a pentadentate aminopyridine ligand.

    Science.gov (United States)

    Du, Junyi; Xu, Daqian; Zhang, Chunxi; Xia, Chungu; Wang, Yong; Sun, Wei

    2016-06-21

    A manganese(ii) complex has been prepared with a proline-derived pentadentate ligand (Pro3Py), and it can be converted to a peroxomanganese(iii) complex in the presence of H2O2 and triethylamine. The resulting peroxomanganese(iii) complex was well characterised by UV-vis, EPR and ESI-MS techniques, and the geometric structure was discussed based on DFT calculations.

  15. Computing Analysis of Bearing Elements of Launch Complex Aggregates for Space Rocket "Soyuz-2.1v"

    Directory of Open Access Journals (Sweden)

    V. A. Zverev

    2014-01-01

    Full Text Available The research is devoted to the computational analysis of bearing structures of launch system aggregates, which are designed for the prelaunch preparation and launch security of space rocket (SR "SOYUZ-2" of 1B stage. The bearing structures taken under consideration are the following: supporting trusses (ST, bearing arms (BA, the upper cable girder (UCG, the umbilical mast (UM. The SR “SOYUZ-2" of 1B stage has the characteristics of the propulsion unit (PU thrust, different from those of the "Soyuz" family space rockets exploited before.The paper presents basic modeling principles to calculate units and their operating loadings. The body self-weight and the influence of a gas-dynamic jet of "SOYUZ-2.1B" propulsion unit have been considered as a load of units. Parameters of this influence are determined on the basis of impulse stream fields and of deceleration temperatures calculated for various SR positions according to the specified path of its ascent and demolition.Physical models of the aggregates and calculations are based on the finite elements method and super-elements method using “SADAS” software package developed at the chair SM8 of Bauman Moscow State Technical University.Fields of nodal temperatures distribution in the ST, BA, UCG, UM models, and fields of tension in finite elements as well represent the calculation results.Obtained results revealed the most vulnerable of considered starting system aggregates, namely UM, which was taken for local durability calculation. As an example, this research considers calculation of local durability in the truss branches junction of UM rotary part, for which the constructive strengthening has been offered. For this node a detailed finite-element model built in the model of UM rotary part has been created. Calculation results of local durability testify that the strengthened node meets durability conditions.SR developers used calculation results of launch system aggregates for the space

  16. Titanium coordination compounds: from discrete metal complexes to metal-organic frameworks.

    Science.gov (United States)

    Assi, Hala; Mouchaham, Georges; Steunou, Nathalie; Devic, Thomas; Serre, Christian

    2017-06-06

    Owing to their promise in photocatalysis and optoelectronics, titanium based metal-organic frameworks (MOFs) are one of the most appealing classes of MOFs reported to date. Nevertheless, Ti-MOFs are still very scarce because of their challenging synthesis associated with a poor degree of control of their chemistry and crystallization. This review aims at giving an overview of the recent progress in this field focusing on the most relevant existing titanium coordination compounds as well as their promising photoredox properties. Not only Ti-MOFs but also Ti-oxo-clusters will be discussed and particular interest will be dedicated to highlight the different successful synthetic strategies allowing to overcome the still "unpredictable" reactivity of titanium ions, particularly to afford crystalline porous coordination polymers.

  17. Metal-catalyzed cycloisomerization as a powerful tool in the synthesis of complex sesquiterpenoids.

    Science.gov (United States)

    Stathakis, Christos I; Gkizis, Petros L; Zografos, Alexandros L

    2016-08-25

    Covering: up to 2015Sesquiterpenoids are consistently attracting the interest of the scientific community due to their promising clinical profile as therapeutic agents. Cycloisomerization of enynes and dienes is a powerful tool in the hands of organic chemists to access them. In the last 20 years the field has witnessed remarkable advances, especially by revealing the capability of platinum and gold complexes to initiate such reactions. Nowadays, cycloisomerizations continue to enrich our knowledge with atom-economical routes and impressive cascades to reach more complex molecules. The current review covers the basic mechanistic aspects of metal catalysis in cycloisomerization reactions and their progress to the synthesis of selected complex sesquiterpenoids.

  18. Role of the coordination center in photocurrent behavior of a tetrathiafulvalene and metal complex dyad.

    Science.gov (United States)

    Sun, Yong-Gang; Ji, Shu-Fang; Huo, Peng; Yin, Jing-Xue; Huang, Yu-De; Zhu, Qin-Yu; Dai, Jie

    2014-03-17

    Small organic molecule-based compounds are considered to be promising materials in photoelectronics and high-performance optoelectronic devices. However, photoelectron conversion research based on functional organic molecule and metal complex dyads is very scarce. We design and prepare a series of compounds containing a tetrathiafulvalene (TTF) moiety substituted with pyridylmethylamide groups of formulas [Ni(acac)2L]·2CH3OH (1), [Cu2I2L2]·THF·2CH3CN (2), and [MnCl2L2]n·2nCH3CH2OH (3) (L = 4,5-bis(3-pyridylmethylamide)-4',5'-bimethylthio-tetrathiafulvalene, acac = acetylacetone) to study the role of the coordination center in photocurrent behavior. Complex 1 is a mononuclear species, and complex 2 is a dimeric species. Complex 3 is a two-dimensional (2-D) coordination polymer. Spectroscopic and electrochemical properties of these complexes indicate that they are electrochemically active materials. The tetrathiafulvalene ligand L is a photoelectron donor in the presence of electron acceptor methylviologen. The effect of metal coordination centers on photocurrent response behavior is examined. The redox-active metal coordination centers should play an important role in improvement of the photocurrent response property. The different morphologies of the electrode films reflect the dimensions in molecular structures of the coordination compounds.

  19. Spectroscopic and Thermal Characterization of Gliclazide, Glibenclamide and Glimeperide Complexes with Transition and Inner Transition Metals

    Directory of Open Access Journals (Sweden)

    MOHAMMAD TAWKIR

    2012-12-01

    Full Text Available Metal complxes of Gliclazide, Glibenclamide and Glimeperide drugs were prepared and characterized based on elemental analysis, FT-IR, Molar conductance and thermal analysis (TGA and DTG technique. From elemental analysis data, the complexes were proposed to have general formulae (GLZ2Co2H2O, (GLZ2Cu, (GLB2Co2H2O, Cu(GLB 2, (GLM 2Hg and (GLM 2La2H2O. The molar conductance data reveal that all the metal complexes are non-electrolytic, IR spectra shows that GLZ, GLB and GLM are coordinated to metal ions in a neutral bidentate manner from the ESR spectra and XRD-spectra. It is found that the geometrical structures of these complexes are tetrahedral Cu(II ,Hg(II and octrahedral Co(II, La(II. The thermal behavior of these complexes studied using thermogravimetric analysis (TGA and DTG techniques. The results obtained shows that the hydrated complexes lose water molecules of hydration followed immediately by decomposition of the anions and ligand molecules in the successive unseparate steps. Thermogravimetric analysis was carried out to study the decomposition and various kinetic parameters. Freeman Carroll and Sharp Wentworth method have been applied for calculation of kinetic parameters. While data from freeman Carroll method have been used to determine various thermodynamic parameters such as order of reactions, energy of activation, frequency factor, entropy change, free energy change and apparent entropy change and order of reaction..

  20. Synthesis, computational, spectroscopic, thermal and antimicrobial activity studies on some metal-urate complexes.

    Science.gov (United States)

    Masoud, Mamdouh S; Ali, Alaa E; Shaker, Medhat A; Elasala, Gehan S

    2012-05-01

    New sixteen uric acid metal complexes of different stoichiometry, stereo-chemistries and modes of interactions were synthesized using different metals Cr, Mn, Fe, Co, Ni, Cu, Cd, UO(2), Na and K. The synthesized complexes were characterized by elemental analysis, spectral (IR, UV-Vis and ESR) methods, thermal analysis (TG, DTA and DSC) and magnetic susceptibility studies. Molecular modeling calculations were used to characterize the ligation sites of the free ligand. Furthermore, quantum chemical parameters of uric acid such as the energies of highest occupied molecular orbital (E(HOMO)), energies of lowest unoccupied molecular orbital (E(LUMO)), the separation energy (ΔE=E(LUMO)-E(HOMO)), the absolute electronegativity, χ, the chemical potential, P(i), the absolute hardness, η and the softness (σ) were obtained for uric acid. Eight different microbial categories were used to study the antimicrobial activity of the free ligand and ten of its complexes. The results indicate that the ligand and its metal complexes possess antimicrobial properties. The stoichiometry of iron-uric acid complex was studied by using different spectrophotometric methods.