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Sample records for ii core complexes

  1. Purification and crystallization of oxygen-evolving photosystem II core complex from thermophilic cyanobacteria.

    PubMed

    Shen, Jian-Ren; Kawakami, Keisuke; Koike, Hiroyuki

    2011-01-01

    This chapter describes the purification and crystallization of oxygen-evolving photosystem II core dimer complex from a thermophilic cyanobacterium Thermosynechococcus vulcanus. Procedures used for purification of photosystem II from the cyanobacterium involves cultivation of cells, isolation of thylakoid membranes, purification of crude and pure photosystem II core complexes by detergent solubilization, followed by differential centrifugation and column chromatography. The purified core dimer particles were successfully used for crystallization, and the methods and conditions used for crystallization are presented. These purification and crystallization procedures can be applied for another thermophilic cyanobacterium T. elongatus.

  2. Spin control in ladderlike hexanuclear copper(II) complexes with metallacyclophane cores.

    PubMed

    Pardo, Emilio; Bernot, Kevin; Julve, Miguel; Lloret, Francesc; Cano, Joan; Ruiz-García, Rafael; Delgado, Fernando S; Ruiz-Pérez, Catalina; Ottenwaelder, Xavier; Journaux, Yves

    2004-05-03

    Two new hexanuclear oxamatocopper(II) complexes 3 and 4 have been synthesized from the binuclear copper(II) complexes of the meta- and para-phenylenebis(oxamate) ligands, respectively. Complexes 3 and 4 possess an overall ladderlike structure made up of two oxamate-bridged linear trinuclear units ("rails") connected through two phenylenediamidate bridges ("rungs") between the central copper atoms to give metallacyclic cores of the meta- and para-cyclophane type, respectively. They show different ground spin states, S = 1 (3) or S = 0 (4), depending on the substitution pattern in the aromatic spacers. The triplet state molecule 3 containing two spin doublet Cu(II)3 units connected by two m-phenylenediamidate bridges represents a successful extension of the concept of "ferromagnetic coupling units" to metal complexes, which is a well-known approach toward high spin organic radicals.

  3. Architecture of the RNA polymerase II-Mediator core initiation complex.

    PubMed

    Plaschka, C; Larivière, L; Wenzeck, L; Seizl, M; Hemann, M; Tegunov, D; Petrotchenko, E V; Borchers, C H; Baumeister, W; Herzog, F; Villa, E; Cramer, P

    2015-02-19

    The conserved co-activator complex Mediator enables regulated transcription initiation by RNA polymerase (Pol) II. Here we reconstitute an active 15-subunit core Mediator (cMed) comprising all essential Mediator subunits from Saccharomyces cerevisiae. The cryo-electron microscopic structure of cMed bound to a core initiation complex was determined at 9.7 Å resolution. cMed binds Pol II around the Rpb4-Rpb7 stalk near the carboxy-terminal domain (CTD). The Mediator head module binds the Pol II dock and the TFIIB ribbon and stabilizes the initiation complex. The Mediator middle module extends to the Pol II foot with a 'plank' that may influence polymerase conformation. The Mediator subunit Med14 forms a 'beam' between the head and middle modules and connects to the tail module that is predicted to bind transcription activators located on upstream DNA. The Mediator 'arm' and 'hook' domains contribute to a 'cradle' that may position the CTD and TFIIH kinase to stimulate Pol II phosphorylation.

  4. Synthesis, molecular docking and evaluation of antifungal activity of Ni(II), Co(II) and Cu(II) complexes of porphyrin core macromolecular ligand.

    PubMed

    Singh, Urvashi; Malla, Ali Mohammad; Bhat, Imtiyaz Ahmad; Ahmad, Ajaz; Bukhari, Mohd Nadeem; Bhat, Sneha; Anayutullah, Syed; Hashmi, Athar Adil

    2016-04-01

    Porphyrin core dendrimeric ligand (L) was synthesized by Rothemund synthetic route in which p-hydroxy benzaldehyde and pyrrole were fused together. The prepared ligand was complexed with Ni(II), Cu(II) and Co(II) ions, separately. Both the ligand and its complexes were characterized by elemental analysis and spectroscopic studies (FT-IR, UV-Vis, (1)HNMR). Square planar geometries were proposed for Cu(II), Ni(II) and Co(II) ions in cobalt, Nickel and copper complexes, respectively on the basis of UV-Vis spectroscopic data. The ligand and its complex were screened on Candida albicans (ATCC 10231), Aspergillus fumigatus (ATCC 1022), Trichophyton mentagrophytes (ATCC 9533) and Pencillium marneffei by determining MICs and inhibition zones. The activity of the ligand and its complexes was found to be in the order: CuL ˃ CoL ≈ NiL ˃ L. Detection of DNA damage at the level of the individual eukaryotic cell was observed by commet assay. Molecular docking technique was used to understand the ligand-DNA interactions. From docking experiment, we conclude that copper complex interacts more strongly than rest two.

  5. Spectroscopic properties of photosystem II core complexes from Thermosynechococcus elongatus revealed by single-molecule experiments.

    PubMed

    Brecht, Marc; Skandary, Sepideh; Hellmich, Julia; Glöckner, Carina; Konrad, Alexander; Hussels, Martin; Meixner, Alfred J; Zouni, Athina; Schlodder, Eberhard

    2014-06-01

    In this study we use a combination of absorption, fluorescence and low temperature single-molecule spectroscopy to elucidate the spectral properties, heterogeneities and dynamics of the chlorophyll a (Chla) molecules responsible for the fluorescence emission of photosystem II core complexes (PS II cc) from the cyanobacterium Thermosynechococcus elongatus. At the ensemble level, the absorption and fluorescence spectra show a temperature dependence similar to plant PS II. We report emission spectra of single PS II cc for the first time; the spectra are dominated by zero-phonon lines (ZPLs) in the range between 680 and 705nm. The single-molecule experiments show unambiguously that different emitters and not only the lowest energy trap contribute to the low temperature emission spectrum. The average emission spectrum obtained from more than hundred single complexes shows three main contributions that are in good agreement with the reported bands F685, F689 and F695. The intensity of F695 is found to be lower than in conventional ensemble spectroscopy. The reason for the deviation might be due to the accumulation of triplet states on the red-most chlorophylls (e.g. Chl29 in CP47) or on carotenoids close to these long-wavelength traps by the high excitation power used in the single-molecule experiments. The red-most emitter will not contribute to the fluorescence spectrum as long as it is in the triplet state. In addition, quenching of fluorescence by the triplet state may lead to a decrease of long-wavelength emission.

  6. Protein film voltammetry and co-factor electron transfer dynamics in spinach photosystem II core complex.

    PubMed

    Zhang, Yun; Magdaong, Nikki; Frank, Harry A; Rusling, James F

    2014-05-01

    Direct protein film voltammetry (PFV) was used to investigate the redox properties of the photosystem II (PSII) core complex from spinach. The complex was isolated using an improved protocol not used previously for PFV. The PSII core complex had high oxygen-evolving capacity and was incorporated into thin lipid and polyion films. Three well-defined reversible pairs of reduction and oxidation voltammetry peaks were observed at 4 °C in the dark. Results were similar in both types of films, indicating that the environment of the PSII-bound cofactors was not influenced by film type. Based on comparison with various control samples including Mn-depleted PSII, peaks were assigned to chlorophyll a (Chl a) (Em = -0.47 V, all vs. NHE, at pH 6), quinones (-0.12 V), and the manganese (Mn) cluster (Em = 0.18 V). PFV of purified iron heme protein cytochrome b-559 (Cyt b-559), a component of PSII, gave a partly reversible peak pair at 0.004 V that did not have a potential similar to any peaks observed from the intact PSII core complex. The closest peak in PSII to 0.004 V is the 0.18 V peak that was found to be associated with a two-electron process, and thus is inconsistent with iron heme protein voltammetry. The -0.47 V peak had a peak potential and peak potential-pH dependence similar to that found for purified Chl a incorporated into DMPC films. The midpoint potentials reported here may differ to various extents from previously reported redox titration data due to the influence of electrode double-layer effects. Heterogeneous electron transfer (hET) rate constants were estimated by theoretical fitting and digital simulations for the -0.47 and 0.18 V peaks. Data for the Chl a peaks were best fit to a one-electron model, while the peak assigned to the Mn cluster was best fit by a two-electron/one-proton model.

  7. Critical assessment of the emission spectra of various photosystem II core complexes.

    PubMed

    Chen, Jinhai; Kell, Adam; Acharya, Khem; Kupitz, Christopher; Fromme, Petra; Jankowiak, Ryszard

    2015-06-01

    We evaluate low-temperature (low-T) emission spectra of photosystem II core complexes (PSII-cc) previously reported in the literature, which are compared with emission spectra of PSII-cc obtained in this work from spinach and for dissolved PSII crystals from Thermosynechococcus (T.) elongatus. This new spectral dataset is used to interpret data published on membrane PSII (PSII-m) fragments from spinach and Chlamydomonas reinhardtii, as well as PSII-cc from T. vulcanus and intentionally damaged PSII-cc from spinach. This study offers new insight into the assignment of emission spectra reported on PSII-cc from different organisms. Previously reported spectra are also compared with data obtained at different saturation levels of the lowest energy state(s) of spinach and T. elongatus PSII-cc via hole burning in order to provide more insight into emission from bleached and/or photodamaged complexes. We show that typical low-T emission spectra of PSII-cc (with closed RCs), in addition to the 695 nm fluorescence band assigned to the intact CP47 complex (Reppert et al. J Phys Chem B 114:11884-11898, 2010), can be contributed to by several emission bands, depending on sample quality. Possible contributions include (i) a band near 690-691 nm that is largely reversible upon temperature annealing, proving that the band originates from CP47 with a bleached low-energy state near 693 nm (Neupane et al. J Am Chem Soc 132:4214-4229, 2010; Reppert et al. J Phys Chem B 114:11884-11898, 2010); (ii) CP43 emission at 683.3 nm (not at 685 nm, i.e., the F685 band, as reported in the literature) (Dang et al. J Phys Chem B 112:9921-9933, 2008; Reppert et al. J Phys Chem B 112:9934-9947, 2008); (iii) trap emission from destabilized CP47 complexes near 691 nm (FT1) and 685 nm (FT2) (Neupane et al. J Am Chem Soc 132:4214-4229, 2010); and (iv) emission from the RC pigments near 686-687 nm. We suggest that recently reported emission of single PSII-cc complexes from T. elongatus may not represent

  8. A new tetranuclear copper(II) Schiff base complex containing Cu 4O 4 cubane core: Structural and spectral characterizations

    NASA Astrophysics Data System (ADS)

    Shit, Shyamapada; Rosair, Georgina; Mitra, Samiran

    2011-04-01

    A new tetra-nuclear coordination complex [Cu 4(HL) 4] ( 1) containing Cu 4O 4 cubane core has been synthesized by using Schiff base ligand [(OH)C 6H 4CH dbnd N sbnd C(CH 3)(CH 2OH) 2] (H 3L), obtained by the 1:1 condensation of 2-amino-2-methyl-1,3-propanediol with salicylaldehyde and thoroughly characterized by micro-analytical, FT-IR, UV-Vis, thermal and room temperature magnetic susceptibility measurements. Structural characterization of the complex has been done by single crystal X-ray diffraction analysis. Structural elucidation reveals versatile coordination modes for two identical alkoxo oxygen atoms of the Schiff base ligand; one in its deprotonated form exhibits μ 3-bridging to bind three similar copper(II) centers whilst the protonated one remains as monodentate or non-coordinating. Structural analysis also shows that the Cu 4O 4 cubane core in 1 consists of four μ 3-alkoxo oxygen bridged copper(II) atoms giving an approximately cubic array of alternating oxygen atoms and copper(II) atoms where the metal centers display both distorted square pyramidal and distorted octahedral geometries.

  9. Effect of aggregation state, temperature and phospholipids on photobleaching of photosynthetic pigments in spinach Photosystem II core complexes.

    PubMed

    Ventrella, A; Catucci, L; Agostiano, A

    2008-06-01

    Photosystem II (PSII) complex activity is known to decrease under strong white light illumination, and this photoinhibition phenomenon is connected to the photobleaching of the PSII photosynthetic pigments. In this work the pigment photobleaching has been studied on PSII core complexes, by observing the effects of different factors such as the aggregation state (PSII monomers and dimers were used), temperature (20 degrees C and 10 degrees C temperatures were tested) and the presence of the exogenous phospholipids (cardiolipin and phosphatidylglycerol). In particular, PSII resistance against white light stress was studied by means of UV/VIS Absorption and Fluorescence Emission measurements. It was found that PSII dimers resulted more resistant against photobleaching and that lower temperature reduces the pigment photodestruction. Moreover, the presence of phosphatidylglycerol or cardiolipin enhanced the PSII resistance to the photobleaching phenomenon, mainly at lower temperatures.

  10. The Tom Core Complex

    PubMed Central

    Ahting, Uwe; Thun, Clemens; Hegerl, Reiner; Typke, Dieter; Nargang, Frank E.; Neupert, Walter; Nussberger, Stephan

    1999-01-01

    Translocation of nuclear-encoded preproteins across the outer membrane of mitochondria is mediated by the multicomponent transmembrane TOM complex. We have isolated the TOM core complex of Neurospora crassa by removing the receptors Tom70 and Tom20 from the isolated TOM holo complex by treatment with the detergent dodecyl maltoside. It consists of Tom40, Tom22, and the small Tom components, Tom6 and Tom7. This core complex was also purified directly from mitochondria after solubilization with dodecyl maltoside. The TOM core complex has the characteristics of the general insertion pore; it contains high-conductance channels and binds preprotein in a targeting sequence-dependent manner. It forms a double ring structure that, in contrast to the holo complex, lacks the third density seen in the latter particles. Three-dimensional reconstruction by electron tomography exhibits two open pores traversing the complex with a diameter of ∼2.1 nm and a height of ∼7 nm. Tom40 is the key structural element of the TOM core complex. PMID:10579717

  11. Direct energy transfer from the major antenna to the photosystem II core complexes in the absence of minor antennae in liposomes.

    PubMed

    Sun, Ruixue; Liu, Kun; Dong, Lianqing; Wu, Yuling; Paulsen, Harald; Yang, Chunhong

    2015-02-01

    Minor antennae of photosystem (PS) II, located between the PSII core complex and the major antenna (LHCII), are important components for the structural and functional integrity of PSII supercomplexes. In order to study the functional significance of minor antennae in the energetic coupling between LHCII and the PSII core, characteristics of PSII-LHCII proteoliposomes, with or without minor antennae, were investigated. Two types of PSII preparations containing different antenna compositions were isolated from pea: 1) the PSII preparation composed of the PSII core complex, all of the minor antennae, and a small amount of major antennae (MCC); and 2) the purified PSII dimeric core complexes without periphery antenna (CC). They were incorporated, together with LHCII, into liposomes composed of thylakoid membrane lipids. The spectroscopic and functional characteristics were measured. 77K fluorescence emission spectra revealed an increased spectral weight of fluorescence from PSII reaction center in the CC-LHCII proteoliposomes, implying energetic coupling between LHCII and CC in the proteoliposomes lacking minor antennae. This result was further confirmed by chlorophyll a fluorescence induction kinetics. The incorporation of LHCII together with CC markedly increased the antenna cross-section of the PSII core complex. The 2,6-dichlorophenolindophenol photoreduction measurement implied that the lack of minor antennae in PSII supercomplexes did not block the energy transfer from LHCII to the PSII core complex. In conclusion, it is possible, in liposomes, that LHCII transfer energy directly to the PSII core complex, in the absence of minor antennae.

  12. On the question of the light-harvesting role of β-carotene in photosystem II and photosystem I core complexes.

    PubMed

    Stamatakis, Kostas; Tsimilli-Michael, Merope; Papageorgiou, George C

    2014-08-01

    β-Carotene is the only carotenoid present in the core complexes of Photosystems I and II. Its proximity to chlorophyll a molecules enables intermolecular electronic interactions, including β-carotene to chlorophyll a electronic excitation transfers. However, it has been well documented that, compared to chlorophylls and to phycobilins, the light harvesting efficiency of β-carotenes for photosynthetic O2 evolution is poor. This is more evident in cyanobacteria than in plants and algae because they lack accessory light harvesting pigments with absorptions that overlap the β-carotene absorption. In the present work we investigated the light harvesting role of β-carotenes in the cyanobacterium Synechococcus sp. PCC 7942 using selective β-carotene excitation and selective Photosystem detection of photo-induced electron transport to and from the intersystem plastoquinones (the plastoquinone pool). We report that, although selectively excited β-carotenes transfer electronic excitation to the chlorophyll a of both photosystems, they enable only the oxidation of the plastoquinone pool by Photosystem I but not its reduction by Photosystem II. This may suggest a light harvesting role for the β-carotenes of the Photosystem I core complex but not for those of the Photosystem II core complex. According to the present investigation, performed with whole cyanobacterial cells, the lower photosynthesis yields measured with β-Car-absorbed light can be attributed to the different excitation trapping efficiencies in the reaction centers of PSI and PSII.

  13. Characterization of the low-temperature triplet state of chlorophyll in photosystem II core complexes: Application of phosphorescence measurements and Fourier transform infrared spectroscopy.

    PubMed

    Zabelin, Alexey A; Neverov, Konstantin V; Krasnovsky, Alexander A; Shkuropatova, Valentina A; Shuvalov, Vladimir A; Shkuropatov, Anatoly Ya

    2016-06-01

    Phosphorescence measurements at 77 K and light-induced FTIR difference spectroscopy at 95 K were applied to study of the triplet state of chlorophyll a ((3)Chl) in photosystem II (PSII) core complexes isolated from spinach. Using both methods, (3)Chl was observed in the core preparations with doubly reduced primary quinone acceptor QA. The spectral parameters of Chl phosphorescence resemble those in the isolated PSII reaction centers (RCs). The main spectral maximum and the lifetime of the phosphorescence corresponded to 955±1 nm and of 1.65±0.05 ms respectively; in the excitation spectrum, the absorption maxima of all core complex pigments (Chl, pheophytin a (Pheo), and β-carotene) were observed. The differential signal at 1667(-)/1628(+)cm(-1) reflecting a downshift of the stretching frequency of the 13(1)-keto C=O group of Chl was found to dominate in the triplet-minus-singlet FTIR difference spectrum of core complexes. Based on FTIR results and literature data, it is proposed that (3)Chl is mostly localized on the accessory chlorophyll that is in triplet equilibrium with P680. Analysis of the data suggests that the Chl triplet state responsible for the phosphorescence and the FTIR difference spectrum is mainly generated due to charge recombination in the reaction center radical pair P680(+)PheoD1(-), and the energy and temporal parameters of this triplet state as well as the molecular environment and interactions of the triplet-bearing Chl molecule are similar in the PSII core complexes and isolated PSII RCs.

  14. Polarization-modulated infrared spectroscopy and x-ray reflectivity of photosystem II core complex at the gas-water interface.

    PubMed Central

    Gallant, J; Desbat, B; Vaknin, D; Salesse, C

    1998-01-01

    The state of photosystem II core complex (PS II CC) in monolayer at the gas-water interface was investigated using in situ polarization-modulated infrared reflection absorption spectroscopy and x-ray reflectivity techniques. Two approaches for preparing and manipulating the monolayers were examined and compared. In the first, PS II CC was compressed immediately after spreading at an initial surface pressure of 5.7 mN/m, whereas in the second, the monolayer was incubated for 30 min at an initial surface pressure of 0.6 mN/m before compression. In the first approach, the protein complex maintained its native alpha-helical conformation upon compression, and the secondary structure of PS II CC was found to be stable for 2 h. The second approach resulted in films showing stable surface pressure below 30 mN/m and the presence of large amounts of beta-sheets, which indicated denaturation of PS II CC. Above 30 mN/m, those films suffered surface pressure instability, which had to be compensated by continuous compression. This instability was correlated with the formation of new alpha-helices in the film. Measurements at 4 degreesC strongly reduced denaturation of PS II CC. The x-ray reflectivity studies indicated that the spread film consists of a single protein layer at the gas-water interface. Altogether, this study provides direct structural and molecular information on membrane proteins when spread in monolayers at the gas-water interface. PMID:9826610

  15. Thermodynamics of electron transfer in oxygenic photosynthetic reaction centers: volume change, enthalpy, and entropy of electron-transfer reactions in manganese-depleted photosystem II core complexes.

    PubMed

    Hou, J M; Boichenko, V A; Diner, B A; Mauzerall, D

    2001-06-19

    We have previously reported the thermodynamic data of electron transfer in photosystem I using pulsed time-resolved photoacoustics [Hou et al. (2001) Biochemistry 40, 7109-7116]. In the present work, using preparations of purified manganese-depleted photosystem II (PS II) core complexes from Synechocystis sp. PCC 6803, we have measured the DeltaV, DeltaH, and estimated TDeltaS of electron transfer on the time scale of 1 micros. At pH 6.0, the volume contraction of PS II was determined to be -9 +/- 1 A3. The thermal efficiency was found to be 52 +/- 5%, which corresponds to an enthalpy change of -0.9 +/- 0.1 eV for the formation of the state P680+Q(A-) from P680*. An unexpected volume expansion on pulse saturation of PS II was observed, which is reversible in the dark. At pH 9.0, the volume contraction, the thermal efficiency, and the enthalpy change were -3.4 +/- 0.5 A3, 37 +/- 7%, and -1.15 +/- 0.13 eV, respectively. The DeltaV of PS II, smaller than that of PS I and bacterial centers, is assigned to electrostriction and analyzed using the Drude-Nernst equation. To explain the small DeltaV for the formation of P680+Q(A-) or Y(Z*)Q(A-), we propose that fast proton transfer into a polar region is involved in this reaction. Taking the free energy of charge separation of PS II as the difference between the energy of the excited-state P680* and the difference in the redox potentials of the donor and acceptor, the apparent entropy change (TDeltaS) for charge separation of PS II is calculated to be negative, -0.1 +/- 0.1 eV at pH 6.0 (P680+Q(A-)) and -0.2 +/- 0.15 eV at pH 9.0 (Y(Z*)Q(A-)). The thermodynamic properties of electron transfer in PS II core reaction centers thus differ considerably from those of bacterial and PS I reaction centers, which have DeltaV of approximately -27 A3, DeltaH of approximately -0.4 eV, and TDeltaS of approximately +0.4 eV.

  16. Variation of exciton-vibrational coupling in photosystem II core complexes from Thermosynechococcus elongatus as revealed by single-molecule spectroscopy.

    PubMed

    Skandary, Sepideh; Hussels, Martin; Konrad, Alexander; Renger, Thomas; Müh, Frank; Bommer, Martin; Zouni, Athina; Meixner, Alfred J; Brecht, Marc

    2015-03-19

    The spectral properties and dynamics of the fluorescence emission of photosystem II core complexes are investigated by single-molecule spectroscopy at 1.6 K. The emission spectra are dominated by sharp zero-phonon lines (ZPLs). The sharp ZPLs are the result of weak to intermediate exciton-vibrational coupling and slow spectral diffusion. For several data sets, it is possible to surpass the effect of spectral diffusion by applying a shifting algorithm. The increased signal-to-noise ratio enables us to determine the exciton-vibrational coupling strength (Huang-Rhys factor) with high precision. The Huang-Rhys factors vary between 0.03 and 0.8. The values of the Huang-Rhys factors show no obvious correlation between coupling strength and wavelength position. From this result, we conclude that electrostatic rather than exchange or dispersive interactions are the main contributors to the exciton-vibrational coupling in this system.

  17. Insights into the photoprotective switch of the major light-harvesting complex II (LHCII): a preserved core of arginine-glutamate interlocked helices complemented by adjustable loops.

    PubMed

    Sunku, Kiran; de Groot, Huub J M; Pandit, Anjali

    2013-07-05

    Light-harvesting antennae of the LHC family form transmembrane three-helix bundles of which two helices are interlocked by conserved arginine-glutamate (Arg-Glu) ion pairs that form ligation sites for chlorophylls. The antenna proteins of photosystem II have an intriguing dual function. In excess light, they can switch their conformation from a light-harvesting into a photoprotective state, in which the excess and harmful excitation energies are safely dissipated as heat. Here we applied magic angle spinning NMR and selective Arg isotope enrichment as a noninvasive method to analyze the Arg structures of the major light-harvesting complex II (LHCII). The conformations of the Arg residues that interlock helix A and B appear to be preserved in the light-harvesting and photoprotective state. Several Arg residues have very downfield-shifted proton NMR responses, indicating that they stabilize the complex by strong hydrogen bonds. For the Arg Cα chemical shifts, differences are observed between LHCII in the active, light-harvesting and in the photoprotective, quenched state. These differences are attributed to a conformational change of the Arg residue in the stromal loop region. We conclude that the interlocked helices of LHCII form a rigid core. Consequently, the LHCII conformational switch does not involve changes in A/B helix tilting but likely involves rearrangements of the loops and helical segments close to the stromal and lumenal ends.

  18. Synthesis, molecular structures and phase transition studies on benzothiazole-cored Schiff bases with their Cu(II) and Pd(II) complexes: Crystal structure of (E)-6-methoxy-2-(4-octyloxy-2-hydroxybenzylideneamino)benzothiazole

    NASA Astrophysics Data System (ADS)

    Yeap, Guan-Yeow; Heng, Boon-Teck; Faradiana, Nur; Zulkifly, Raihana; Ito, Masato M.; Tanabe, Makoto; Takeuchi, Daisuke

    2012-03-01

    Two new homologous series of Cu(II) and Pd(II) complexes with benzothiazole-cored Schiff bases have been synthesised with the aim to study the mesomorphic and thermal properties of ligands upon formation of metal complexes. The molecular structure of title compounds were elucidated with the employment of FT-IR, 1D and 2D FT-NMR spectroscopic techniques. Mesomorphic and thermal behaviour of title compounds have been investigated by differential scanning calorimetry and polarising optical microscope. All the ligands are nematogenic but the corresponding Cu(II) and Pd(II) complexes crystallised in ordinary solid. The conformation of 6-methoxy-2-(4-octyloxy-2-hydroxy-benzylideneamino)benzothiazole was determined by single crystal X-ray diffraction analysis of which the title compound favours more stable (E)-6-methoxy-2-(4-octyloxy-2-hydroxybenzylideneamino)benzothiazole. Crystal structure of the title compound also revealed that the bond length of Cdbnd N (1.303 Å) in the benzothiazole rings very close to that in the exocyclic Cdbnd N linkage (1.298 Å).

  19. Calcium controls the assembly of the photosynthetic water-oxidizing complex: a cadmium(II) inorganic mutant of the Mn4Ca core.

    PubMed

    Bartlett, John E; Baranov, Sergei V; Ananyev, Gennady M; Dismukes, G Charles

    2008-03-27

    Perturbation of the catalytic inorganic core (Mn4Ca1OxCly) of the photosystem II-water-oxidizing complex (PSII-WOC) isolated from spinach is examined by substitution of Ca2+ with cadmium(II) during core assembly. Cd2+ inhibits the yield of reconstitution of O2-evolution activity, called photoactivation, starting from the free inorganic cofactors and the cofactor-depleted apo-WOC-PSII complex. Ca2+ affinity increases following photooxidation of the first Mn2+ to Mn3+ bound to the 'high-affinity' site. Ca2+ binding occurs in the dark and is the slowest overall step of photoactivation (IM1-->IM1* step). Cd2+ competitively blocks the binding of Ca2+ to its functional site with 10- to 30-fold higher affinity, but does not influence the binding of Mn2+ to its high-affinity site. By contrast, even 10-fold higher concentrations of Cd2+ have no effect on O2-evolution activity in intact PSII-WOC. Paradoxically, Cd2+ both inhibits photoactivation yield, while accelerating the rate of photoassembly of active centres 10-fold relative to Ca2+. Cd2+ increases the kinetic stability of the photooxidized Mn3+ assembly intermediate(s) by twofold (mean lifetime for dark decay). The rate data provide evidence that Cd2+ binding following photooxidation of the first Mn3+, IM1-->IM1*, causes three outcomes: (i) a longer intermediate lifetime that slows IM1 decay to IM0 by charge recombination, (ii) 10-fold higher probability of attaining the degrees of freedom (either or both cofactor and protein d.f.) needed to bind and photooxidize the remaining 3 Mn2+ that form the functional cluster, and (iii) increased lability of Cd2+ following Mn4 cluster assembly results in (re)exchange of Cd2+ by Ca2+ which restores active O2-evolving centres. Prior EPR spectroscopic data provide evidence for an oxo-bridged assembly intermediate, Mn3+(mu-O2(-))Ca2+, for IM1*. We postulate an analogous inhibited intermediate with Cd2+ replacing Ca2+.

  20. Temperature Dependence of Light-Induced Absorbance Changes Associated with Chlorophyll Photooxidation in Manganese-Depleted Core Complexes of Photosystem II.

    PubMed

    Zabelin, A A; Shkuropatova, V A; Shkuropatov, A Ya; Shuvalov, V A

    2015-10-01

    Mid-infrared (4500-1150 cm(-1)) absorbance changes induced by continuous illumination of Mn-depleted core complexes of photosystem II (PSII) from spinach in the presence of exogenous electron acceptors (potassium ferricyanide and silicomolybdate) were studied by FTIR difference spectroscopy in the temperature range 100-265 K. The FTIR difference spectrum for photooxidation of the chlorophyll dimer P680 was determined from the set of signals associated with oxidation of secondary electron donors (β-carotene, chlorophyll) and reduction of the primary quinone QA. On the basis of analysis of the temperature dependence of the P680(+)/P680 FTIR spectrum, it was concluded that frequencies of 13(1)-keto-C=O stretching modes of neutral chlorophyll molecules PD1 and PD2, which constitute P680, are similar to each other, being located at ~1700 cm(-1). This together with considerable difference between the stretching mode frequencies of keto groups of PD1(+) and PD2(+) cations (1724 and 1709 cm(-1), respectively) is in agreement with a literature model (Okubo et al. (2007) Biochemistry, 46, 4390-4397) suggesting that the positive charge in the P680(+) dimer is mainly localized on one of the two chlorophyll molecules. A partial delocalization of the charge between the PD1 and PD2 molecules in P680(+) is supported by the presence of a characteristic electronic intervalence band at ~3000 cm(-1). It is shown that a bleaching band at 1680 cm(-1) in the P680(+)/P680 FTIR spectrum does not belong to P680. A possible origin of this band is discussed, taking into account the temperature dependence (100-265 K) of light-induced absorbance changes of PSII core complexes in the visible spectral region from 620 to 720 nm.

  1. Effect of protein modification by malondialdehyde on the interaction between the oxygen-evolving complex 33 kDa protein and photosystem II core proteins.

    PubMed

    Yamauchi, Yasuo; Sugimoto, Yukihiro

    2010-04-01

    Previously we observed that the oxygen-evolving complex 33 kDa protein (OEC33) which stabilizes the Mn cluster in photosystem II (PSII), was modified with malondialdehyde (MDA), an end-product of peroxidized polyunsaturated fatty acids, and the modification increased in heat-stressed plants (Yamauchi et al. 2008). In this study, we examined whether the modification of OEC33 with MDA affects its binding to the PSII complex and causes inactivation of the oxygen-evolving complex. Purified OEC33 and PSII membranes that had been removed of extrinsic proteins of the oxygen-evolving complex (PSIIOEE) of spinach (Spinacia oleracea) were separately treated with MDA. The binding was diminished when both OEC33 and PSIIOEE were modified, but when only OEC33 or PSIIOEE was treated, the binding was not impaired. In the experiment using thylakoid membranes, release of OEC33 from PSII and corresponding loss of oxygen-evolving activity were observed when thylakoid membranes were treated with MDA at 40 degrees C but not at 25 degrees C. In spinach leaves treated at 40 degrees C under light, maximal efficiency of PSII photochemistry (F(v)/F(m) ratio of chlorophyll fluorescence) and oxygen-evolving activity decreased. Simultaneously, MDA contents in heat-stressed leaves increased, and OEC33 and PSII core proteins including 47 and 43 kDa chlorophyll-binding proteins were modified with MDA. In contrast, these changes were to a lesser extent at 40 degrees C in the dark. These results suggest that MDA modification of PSII proteins causes release of OEC33 from PSII and it is promoted in heat and oxidative conditions.

  2. Variation of the ground spin state in homo- and hetero-octanuclear copper(II) and nickel(II) double-star complexes with a meso-helicate-type metallacryptand core.

    PubMed

    Pardo, Emilio; Dul, Marie-Claire; Lescouëzec, Rodrigue; Chamoreau, Lise-Marie; Journaux, Yves; Pasán, Jorge; Ruiz-Pérez, Catalina; Julve, Miguel; Lloret, Francesc; Ruiz-García, Rafael; Cano, Joan

    2010-05-28

    Homo- and heterometallic octanuclear complexes of formula Na₂{[Cu₂(mpba)₃][Cu(Me₅dien)]₆}-(ClO₄)₆·12H₂O (1), Na₂{[Cu₂(Mempba)₃][Cu(Me₅dien)]₆}(ClO₄)₆·12H₂O (2), Na₂{[Ni₂(mpba)₃]-[Cu(Me₅dien)]₆}(ClO₄)₆·12H₂O (3), Na₂{[Ni₂(Mempba)₃][Cu(Me₅dien)]₆}(ClO₄)₆·9H₂O (4), {[Ni₂(mpba)₃][Ni(dipn)(H₂O)]₆}(ClO₄)₄·12.5H₂O (5), and {[Ni₂(Mempba)₃][Ni(dipn)-(H₂O)]₆}(ClO₄)₄·12H₂O (6) [mpba = 1,3-phenylenebis(oxamate), Mempba = 4-methyl-1,3-phenylenebis(oxamate), Me₅dien = N,N,N',N'',N''-pentamethyldiethylenetriamine, and dipn = dipropylenetriamine] have been synthesized through the "complex-as-ligand/complex-as-metal" strategy. Single-crystal X-ray diffraction analyses of 1, 3, and 5 show cationic M(II)₂M'(II)₆ entities (M, M' = Cu and Ni) with an overall double-star architecture, which is made up of two oxamato-bridged M(II)M'(II)₃ star units connected through three meta-phenylenediamidate bridges between the two central metal atoms leading to a binuclear metallacryptand core of the meso-helicate-type. Dc magnetic susceptibility data for 1-6 in the temperature range 2-300 K have been analyzed through a "dimer-of-tetramers" model [H = - J(S(1A)·S(3A) + S(1A)·S(4A) + S(1A)·S(5A) + S(2B)·S(6B) + S(2B)·S(7B) + S(2B)·S(8B)) - J'S(1A)·S(2B), with S(1A) = S(2B) = S(M) and S(3A) = S(4A) = S(5A) = S(6B) = S(7B) = S(8B) = S(M')]. The moderate to strong antiferromagnetic coupling between the M(II) and M'(II) ions through the oxamate bridge in 1-6 (-J(Cu-Cu) = 52.0-57.0 cm⁻¹, -J(Ni-Cu) = 39.1-44.7 cm⁻¹, and -J(Ni-Ni) = 26.3-26.6 cm⁻¹) leads to a non-compensation of the ground spin state for the tetranuclear M(II)M'(II)₃ star units [S(A) = S(B) = 3S(M') - S(M) = 1 (1 and 2), 1/2 (3 and 4), and 2 (5 and 6)]. Within the binuclear M(II)₂ meso-helicate cores of 1-4, a moderate to weak antiferromagnetic coupling between the M(II) ions (-J'(Cu-Cu) = 28.0-48.0 cm⁻¹ and -J

  3. Multireversible redox processes in pentanuclear bis(triple-helical) manganese complexes featuring an oxo-centered triangular {Mn(II)2Mn(III)(μ3-O)}5+ or {Mn(II)Mn(III)2(μ3-O)}6+ core wrapped by two {Mn(II)2(bpp)3}-.

    PubMed

    Romain, Sophie; Rich, Jordi; Sens, Cristina; Stoll, Thibaut; Benet-Buchholz, Jordi; Llobet, Antoni; Rodriguez, Montserrat; Romero, Isabel; Clérac, Rodolphe; Mathonière, Corine; Duboc, Carole; Deronzier, Alain; Collomb, Marie-Noëlle

    2011-09-05

    A new pentanuclear bis(triple-helical) manganese complex has been isolated and characterized by X-ray diffraction in two oxidation states: [{Mn(II)(μ-bpp)(3)}(2)Mn(II)(2)Mn(III)(μ-O)](3+) (1(3+)) and [{Mn(II)(μ-bpp)(3)}(2)Mn(II)Mn(III)(2)(μ-O)](4+) (1(4+)). The structure consists of a central {Mn(3)(μ(3)-O)} core of Mn(II)(2)Mn(III) (1(3+)) or Mn(II)Mn(III)(2) ions (1(4+)) which is connected to two apical Mn(II) ions through six bpp(-) ligands. Both cations have a triple-stranded helicate configuration, and a pair of enantiomers is present in each crystal. The redox properties of 1(3+) have been investigated in CH(3)CN. A series of five distinct and reversible one-electron waves is observed in the -1.0 and +1.50 V potential range, assigned to the Mn(II)(4)Mn(III)/Mn(II)(5), Mn(II)(3)Mn(III)(2)/Mn(II)(4)Mn(III), Mn(II)(2)Mn(III)(3)/Mn(II)(3)Mn(III)(2), Mn(II)Mn(III)(4)/Mn(II)(2)Mn(III)(3), and Mn(III)(5)/Mn(II)Mn(III)(4) redox couples. The two first oxidation processes leading to Mn(II)(3)Mn(III)(2) (1(4+)) and Mn(II)(2)Mn(III)(3) (1(5+)) are related to the oxidation of the Mn(II) ions of the central core and the two higher oxidation waves, close in potential, are thus assigned to the oxidation of the two apical Mn(II) ions. The 1(4+) and 1(5+) oxidized species and the reduced Mn(4)(II) (1(2+)) species are quantitatively generated by bulk electrolyses demonstrating the high stability of the pentanuclear structure in four oxidation states (1(2+) to 1(5+)). The spectroscopic characteristics (X-band electron paramagnetic resonance, EPR, and UV-visible) of these species are also described as well as the magnetic properties of 1(3+) and 1(4+) in solid state. The powder X- and Q-band EPR signature of 1(3+) corresponds to an S = 5/2 spin state characterized by a small zero-field splitting parameter (|D| = 0.071 cm(-1)) attributed to the two apical Mn(II) ions. At 40 K, the magnetic behavior is consistent for 1(3+) with two apical S = 5/2 {Mn(II)(bpp)(3)}(-) and one S

  4. Synthetic model of the asymmetric [Mn3CaO4] cubane core of the oxygen-evolving complex of photosystem II.

    PubMed

    Mukherjee, Shreya; Stull, Jamie A; Yano, Junko; Stamatatos, Theocharis C; Pringouri, Konstantina; Stich, Troy A; Abboud, Khalil A; Britt, R David; Yachandra, Vittal K; Christou, George

    2012-02-14

    The laboratory synthesis of the oxygen-evolving complex (OEC) of photosystem II has been the objective of synthetic chemists since the early 1970s. However, the absence of structural information on the OEC has hampered these efforts. Crystallographic reports on photosystem II that have been appearing at ever-improving resolution over the past ten years have finally provided invaluable structural information on the OEC and show that it comprises a [Mn(3)CaO(4)] distorted cubane, to which is attached a fourth, external Mn atom, and the whole unit attached to polypeptides primarily by aspartate and glutamate carboxylate groups. Such a heterometallic Mn/Ca cubane with an additional metal attached to it has been unknown in the literature. This paper reports the laboratory synthesis of such an asymmetric cubane-containing compound with a bound external metal atom, [(1)]. All peripheral ligands are carboxylate or carboxylic acid groups. Variable-temperature magnetic susceptibility data have established 1 to possess an S = 9/2 ground state. EPR spectroscopy confirms this, and the Davies electron nuclear double resonance data reveal similar hyperfine couplings to those of other Mn(IV) species, including the OEC S(2) state. Comparison of the X-ray absorption data with those for the OEC reveal 1 to possess structural parameters that make it a close structural model of the asymmetric-cubane OEC unit. This geometric and electronic structural correspondence opens up a new front in the multidisciplinary study of the properties and function of this important biological unit.

  5. ΔpH-dependent non-photochemical quenching (qE) of excited chlorophylls in the photosystem II core complex of the freshwater cyanobacterium Synechococcus sp PCC 7942.

    PubMed

    Stamatakis, Kostas; Papageorgiou, George C

    2014-08-01

    Light-induced and lumen acidity-dependent quenching (qE) of excited chlorophylls (Chl) in vivo has been amply documented in plants and algae, but not in cyanobacteria, using primarily the saturation pulse method of quenching analysis which is applied to continuously illuminated samples. This method is unsuitable for cyanobacteria because the background illumination elicits in them a very large Chl a fluorescence signal, due to a state 2 to state 1 transition, which masks fluorescence changes due to other causes. We investigated the qE problem in the cyanobacterium Synechococcus sp. PCC 7942 using a kinetic method (Chl a fluorescence induction) with which qE can be examined before the onset of the state 2 to state 1 transition and the attendant rise of Chl a fluorescence. Our results confirm the existence of a qE mechanism that operates on excited Chls a in Photosystem II core complexes of cyanobacteria.

  6. Mixed metal bis(mu-oxo) complexes with [CuM(mu-O)2]n+(M = Ni(III) or Pd(II)) cores.

    PubMed

    Aboelella, Nermeen W; York, John T; Reynolds, Anne M; Fujita, Koyu; Kinsinger, Christopher R; Cramer, Christopher J; Riordan, Charles G; Tolman, William B

    2004-08-07

    Two highly reactive heterodinuclear bis(mu-oxo) complexes were prepared by combining mononuclear peroxo species with reduced metal precursors at -80 degrees C and were identified by UV-vis, EPR/NMR, and resonance Raman spectroscopy, with corroboration in the case of the CuPd system from density functional calculations.

  7. Molecular-programmed self-assembly of homo- and heterometallic penta- and hexanuclear coordination compounds: synthesis, crystal structures, and magnetic properties of ladder-type CuII2MIIx (M=Cu, Ni; x=3, 4) oxamato complexes with CuII2 metallacyclophane cores.

    PubMed

    Pardo, Emilio; Ruiz-García, Rafael; Lloret, Francesc; Julve, Miguel; Cano, Joan; Pasán, Jorge; Ruiz-Pérez, Catalina; Filali, Yasmine; Chamoreau, Lise-Marie; Journaux, Yves

    2007-05-28

    New homo- and heterometallic, hexa- and pentanuclear complexes of formula {[Cu2(mpba)2(H2O)F][Cu(Me5dien)]4}(PF6)(3).5H2O (1), {[Cu2(Me3mpba)2(H2O)2][Cu(Me5dien)]4}(ClO4)(4).12H2O (2), {[Cu2(ppba)2][Cu(Me5dien)]4}(ClO4)4 (3), and [Ni(cyclam)]{[Cu2(mpba)2][Ni(cyclam)]3}(ClO4)(4).6H2O (4) [mpba=1,3-phenylenebis(oxamate), Me3mpba=2,4,6-trimethyl-1,3-phenylenebis(oxamate), ppba=1,4-phenylenebis(oxamate), Me5dien=N,N,N'N' ',N' '-pentamethyldiethylenetriamine, and cyclam=1,4,8,11-tetraazacyclotetradecane] have been synthesized through the use of the "complex-as-ligand/complex-as-metal" strategy. The structures of 1-3 consist of cationic CuII6 entities with an overall [2x2] ladder-type architecture which is made up of two oxamato-bridged CuII3 linear units connected through two m- or p-phenylenediamidate bridges between the two central copper atoms to give a binuclear metallacyclic core of the cyclophane-type. Complex 4 consists of cationic CuII2NiII3 entities with an incomplete [2x2] ladder-type architecture which is made up of oxamato-bridged CuIINiII and CuIINiII2 linear units connected through two m-phenylenediamidate bridges between the two copper atoms to give a binuclear metallacyclophane core. The magnetic properties of 1-3 and 4 have been interpreted according to their distinct "dimer-of-trimers" and "dimer-plus-trimer" structures, respectively, (H=-J(S1A.S3A+S1A.S4A+S2B.S5B+S2B.S6B)-J'S1A.S2B). Complexes 1-4 exhibit moderate to strong antiferromagnetic coupling through the oxamate bridges (-JCu-Cu=81.3-105.9 cm-1; -JCu-Ni=111.6 cm-1) in the trinuclear and/or binuclear units. Within the binuclear metallacyclophane core, a weak to moderate ferromagnetic coupling (J'Cu-Cu=1.7-9.0 cm-1) operates through the double m-phenylenediamidate bridge, while a strong antiferromagnetic coupling (J'Cu-Cu=-120.6 cm-1) is mediated by the double p-phenylenediamidate bridge.

  8. Removal of Ca(2+) from the Oxygen-Evolving Complex in Photosystem II Has Minimal Effect on the Mn4O5 Core Structure: A Polarized Mn X-ray Absorption Spectroscopy Study.

    PubMed

    Lohmiller, Thomas; Shelby, Megan L; Long, Xi; Yachandra, Vittal K; Yano, Junko

    2015-10-29

    Ca(2+)-depleted and Ca(2+)-reconstituted spinach photosystem II was studied using polarized X-ray absorption spectroscopy of oriented PS II preparations to investigate the structural and functional role of the Ca(2+) ion in the Mn4O5Ca cluster of the oxygen-evolving complex (OEC). Samples were prepared by low pH/citrate treatment as one-dimensionally ordered membrane layers and poised in the Ca(2+)-depleted S1 (S1') and S2 (S2') states, the S2'YZ(•) state, at which point the catalytic cycle of water oxidation is inhibited, and the Ca(2+)-reconstituted S1 state. Polarized Mn K-edge XANES and EXAFS spectra exhibit pronounced dichroism. Polarized EXAFS data of all states of Ca(2+)-depleted PS II investigated show only minor changes in distances and orientations of the Mn-Mn vectors compared to the Ca(2+)-containing OEC, which may be attributed to some loss of rigidity of the core structure. Thus, removal of the Ca(2+) ion does not lead to fundamental distortion or rearrangement of the tetranuclear Mn cluster, which indicates that the Ca(2+) ion in the OEC is not critical for structural maintenance of the cluster, at least in the S1 and S2 states, but fulfills a crucial catalytic function in the mechanism of the water oxidation reaction. On the basis of this structural information, reasons for the inhibitory effect of Ca(2+) removal are discussed, attributing to the Ca(2+) ion a fundamental role in organizing the surrounding (substrate) water framework and in proton-coupled electron transfer to YZ(•) (D1-Tyr161).

  9. Removal of Ca2+ from the Oxygen-Evolving Complex in Photosystem II Has Minimal Effect on the Mn4O5 Core Structure: A Polarized Mn X-ray Absorption Spectroscopy Study

    DOE PAGES

    Lohmiller, Thomas; Shelby, Megan L.; Long, Xi; ...

    2015-05-19

    We studied Ca2+ -depleted and Ca2+ -reconstituted spinach photosystem II using polarized X-ray absorption spectroscopy of oriented PS II preparations to investigate the structural and functional role of the Ca2+ ion in the Mn4O5Ca cluster of the oxygen-evolving complex (OEC). Samples were prepared by low pH/citrate treatment as one-dimensionally ordered membrane layers and poised in the Ca2+ -depleted S1 (S1') and S2 (S2') states, the S2'YZ• state, at which point the catalytic cycle of water oxidation is inhibited, and the Ca2+ -reconstituted S1 state. Polarized Mn K-edge XANES and EXAFS spectra exhibit pronounced dichroism. Polarized EXAFS data of all statesmore » of Ca2+ -depleted PS II investigated show only minor changes in distances and orientations of the Mn-Mn vectors compared to the Ca2+ -containing OEC, which may be attributed to some loss of rigidity of the core structure. Thus, removal of the Ca2+ ion does not lead to fundamental distortion or rearrangement of the tetranuclear Mn cluster, which indicates that the Ca2+ ion in the OEC is not critical for structural maintenance of the cluster, at least in the S1 and S2 states, but fulfills a crucial catalytic function in the mechanism of the water oxidation reaction. On the basis of this structural information, reasons for the inhibitory effect of Ca2+ removal are discussed, attributing to the Ca2+ ion a fundamental role in organizing the surrounding (substrate) water framework and in proton-coupled electron transfer to YZ• (D1-Tyr161).« less

  10. Highly fluorescent platinum(II) organometallic complexes of perylene and perylene monoimide, with Pt σ-bonded directly to the perylene core.

    PubMed

    Lentijo, Sergio; Miguel, Jesús A; Espinet, Pablo

    2010-10-18

    3-Bromoperylene (BrPer) or N-(2,5-di-tert-butylphenyl)-9-bromo-perylene-3,4-dicarboximide (BrPMI) react with [Pt(PEt(3))(4)] to yield trans-[PtR(PEt(3))(2)Br] (R = Per, 1a; R = PMI, 1b). Neutral and cationic perylenyl complexes containing a Pt(PEt(3))X group have been prepared from 1a,b by substitution of the Br ligand by a variety of other ligands (NCS, CN, NO(3), CN(t)Bu, PyMe). The X-ray structures of trans-[PtR(PEt(3))(2)X] (R = Per, X = NCS (2a); R = PMI, X = NO(3) (4b); R = Per, X = CN(t)Bu (5a)) show that the perylenyl fragment remains nearly planar and is arranged almost orthogonal to the coordination plane: The three molecules appear as individual entities in the solid state, with no π-π stacking of perylenyl rings. Each platinum complex exhibits fluorescence associated to the perylene or PMI fragments with emission quantum yields, in solution at room temperature, in the range 0.30-0.80 and emission lifetimes ∼4 ns, but with significantly different emission maxima, by influence of the X ligands on Pt. The similarity of the overall luminescence spectra of these metalated complexes with the perylene or PMI strongly suggests a perylene-dominated intraligand π-π*emissive state, metal-perturbed by interaction of the platinum fragment mostly via polarization of the Ar-Pt bond.

  11. Thermal history of a metamorphic core complex

    NASA Technical Reports Server (NTRS)

    Dokka, R. K.; Mahaffie, M. J.; Snoke, A. W.

    1985-01-01

    Fission track (FT) thermochronology studies of lower plate rocks of the Ruby Mountains-East Humbolt Range metamorphic core complex provide important constraints on the timing an nature of major middle Tertiary extension of northeast Nevada. Rocks analyzed include several varieties of mylonitic orthogneiss as well as amphibolitic orthognesses from the non-mylonitic infrastructural core. Oligocene-age porphyritic biotite granodiorite of the Harrison Pass pluton was also studied. The minerals dated include apatite, zircon, and sphene and were obtained from the same rocks that have been previously studied. FT ages are concordant and range in age from 26.4 Ma to 23.8 Ma, with all showing overlap at 1 sigma between 25.4 to 23.4 Ma. Concordancy of all FT ages from all structural levels indicates that the lower plate cooled rapidly from temperatures above approx. 285 C (assumed sphene closure temperature (2)) to below approx. 150 C (assumed apatite closure temperature) near the beginning of the Miocene. This suggests that the lower plate cooled at a rate of at least approx. 36 deg C/Ma during this event. Rapid cooling of the region is considered to reflect large-scale tectonic denudation (intracrustal thinning), the vertical complement to intense crustal extension. FT data firmly establish the upper limit on the timing of mylonitization during detachment faulting and also coincide with the age of extensive landscape disruption.

  12. Birth and death of oceanic core complexes

    NASA Astrophysics Data System (ADS)

    MacLeod, C. J.; Searle, R. C.; Murton, B. J.; Scientific Party, Jc007

    2009-04-01

    Oceanic core complexes (OCCs) are the uplifted footwalls of very-large-offset low-angle normal faults that exhume lower crust and mantle rocks onto the seafloor at slow-spreading ridges. Although it is suggested on the basis of numerical modelling that they form during periods of relatively reduced magma supply, little is known about how they initiate or how they are terminated, nor why only certain normal fault systems develop into core complexes. Here we present results from a near-bottom sidescan sonar/bathymetric profiler survey and sampling study of the Mid-Atlantic Ridge near 13˚ N that demonstrate the critical controls on OCC development and evolution. OCC detachment faults initiate as high-angle (65˚ ±10˚ ) normal faults no different from surrounding valley-wall faults and, like them, rapidly flatten to dips of ~30˚ in response to flexural unloading; however, on certain structures displacement continues rather than jumping inward onto a new normal fault, resulting in locally enhanced uplift of the footwall and further flattening of the fault to the horizontal or beyond. Detachment fault formation is triggered primarily by local waning of magma supply, greatly aided by strain localisation due to seawater penetration and talc formation along the fault zones. Volcanism is suppressed or absent when the OCCs are active. The detachments are terminated as neovolcanic ridges propagate laterally across them from magmatically robust segments along strike. Our observations demonstrate how spatial (~100-101km) and temporal (105-106yr) variations in magma flux to the ridge axis directly control the formation, extent and duration of tectonic spreading at the Mid-Atlantic Ridge.

  13. Novel point mutations and mutational complexes in the enhancer II, core promoter and precore regions of hepatitis B virus genotype D1 associated with hepatocellular carcinoma in Saudi Arabia.

    PubMed

    Khan, Anis; Al Balwi, Mohammed A; Tanaka, Yasuhito; Hajeer, Ali; Sanai, Faisal M; Al Abdulkarim, Ibrahim; Al Ayyar, Latifah; Badri, Motasim; Saudi, Dib; Tamimi, Waleed; Mizokami, Masashi; Al Knawy, Bandar

    2013-12-15

    In this study, a cohort of 182 patients [55 hepatocellular carcinoma (HCC) and 127 non-HCC] infected with hepatitis B virus (HBV) in Saudi Arabia was investigated to study the relationship between sequence variation in the enhancer II (EnhII), basal core promoter (BCP) and precore regions of HBV genotype D (HBV/D) and the risk of HCC. HBV genotypes were determined by sequencing analysis and/or enzyme-linked immunosorbent assay. Variations in the EnhII, BCP and precore regions were compared between 107 non-HCC and 45 HCC patients infected with HBV/D, followed by age-matched analysis of 40 cases versus equal number of controls. Age and male gender were significantly associated with HCC (p = 0.0001 and p = 0.03, respectively). Serological markers such as aspartate aminotransferase, albumin and anti-HBe were significantly associated with HCC (p = 0.0001 for all), whereas HBeAg positivity was associated with non-HCC (p = 0.0001). The most prevalent HBV genotype was HBV/D (94%), followed by HBV/E (4%), HBV/A (1.6%) and HBV/C (0.5%). For HBV/D1, genomic mutations associated with HCC were T1673/G1679, G1727, C1741, C1761, A1757/T1764/G1766, T1773, T1773/G1775 and C1909. Age- and gender-adjusted stepwise logistic regression analysis indicated that mutations G1727 [odds ratio (OR) = 18.3; 95% confidence interval (CI) = 2.8-118.4; p = 0.002], A1757/T1764/G1766 (OR = 4.7; 95% CI = 1.3-17.2; p = 0.01) and T1773 (OR = 14.06; 95% CI = 2.3-84.8; p = 0.004) are independent predictors of HCC development. These results implicate novel individual and combination patterns of mutations in the X/precore region of HBV/D1 as predictors of HCC. Risk stratification based on these mutation complexes would be useful in determining high-risk patients and improving diagnostic and treatment strategies for HBV/D1.

  14. Modeling the Arm II core in MicroCap IV

    SciTech Connect

    Dalton, A.C.

    1996-11-01

    This paper reports on how an electrical model for the core of the Arm II machine was created and how to use this model. We wanted to get a model for the electrical characteristics of the ARM II core, in order to simulate this machine and to assist in the design of a future machine. We wanted this model to be able to simulate saturation, variable loss, and reset. Using the Hodgdon model and the circuit analysis program MicroCap IV, this was accomplished. This paper is written in such a way as to allow someone not familiar with the project to understand it.

  15. Meteoric water in metamorphic core complexes

    NASA Astrophysics Data System (ADS)

    Teyssier, Christian; Mulch, Andreas

    2015-04-01

    The trace of surface water has been found in all detachment shear zones that bound the Cordilleran metamorphic core complexes of North America. DeltaD values of mica fish in detachment mylonites demonstrate that these synkinematic minerals grew in the presence of meteoric water. Typically deltaD values are very negative (-120 to -160 per mil) corresponding to deltaD values of water that are < -100 per mil given the temperature of water-mica isotopic equilibration (300-500C). From British Columbia (Canada) to Nevada (USA) detachment systems bound a series of core complexes: the Thor-Odin, Valhalla, Kettle-Okanogan, Bitterroot -Anaconda, Pioneer, Raft River, Ruby Mountain, and Snake Range. The bounding shear zones range in thickness from ~100 m to ~1 km, and within the shear zones, meteoric water signature is recognized over 10s to 100s of meters beneath the detachment fault. The age of shearing ranges generally from Eocene in the N (~50-45 Ma) to Oligo-Miocene in the S (25-15 Ma). DeltaD water values derived from mica fish in shear zones are consistent with supradetachment basin records of the same age brackets and can be used for paleoaltimetry if coeval isotopic records from near sea level are available. Results show that a wave of topography (typically 4000-5000 m) developed from N to S along the Cordillera belt from Eocene to Miocene, accompanied by the propagation of extensional deformation and volcanic activity. In addition, each detachment system informs a particular extensional detachment process. For example, the thick Thor-Odin detachment shear zone provides sufficient age resolution to indicate the downward propagation of shearing and the progressive incorporation of footwall rocks into the hanging wall. The Kettle detachment provides a clear illustration of the dependence of fluid circulation on dynamic recrystallization processes. The Raft River system consists of a thick Eocene shear zone that was overprinted by Miocene shearing; channels of meteoric

  16. Modularized functions of the Fanconi anemia core complex.

    PubMed

    Huang, Yaling; Leung, Justin W C; Lowery, Megan; Matsushita, Nobuko; Wang, Yucai; Shen, Xi; Huong, Do; Takata, Minoru; Chen, Junjie; Li, Lei

    2014-06-26

    The Fanconi anemia (FA) core complex provides the essential E3 ligase function for spatially defined FANCD2 ubiquitination and FA pathway activation. Of the seven FA gene products forming the core complex, FANCL possesses a RING domain with demonstrated E3 ligase activity. The other six components do not have clearly defined roles. Through epistasis analyses, we identify three functional modules in the FA core complex: a catalytic module consisting of FANCL, FANCB, and FAAP100 is absolutely required for the E3 ligase function, and the FANCA-FANCG-FAAP20 and the FANCC-FANCE-FANCF modules provide nonredundant and ancillary functions that help the catalytic module bind chromatin or sites of DNA damage. Disruption of the catalytic module causes complete loss of the core complex function, whereas loss of any ancillary module component does not. Our work reveals the roles of several FA gene products with previously undefined functions and a modularized assembly of the FA core complex.

  17. Luminescent liquid crystalline materials based on palladium(II) imine derivatives containing the 2-phenylpyridine core.

    PubMed

    Micutz, Marin; Iliş, Monica; Staicu, Teodora; Dumitraşcu, Florea; Pasuk, Iuliana; Molard, Yann; Roisnel, Thierry; Cîrcu, Viorel

    2014-01-21

    In this work we report our studies concerning the synthesis and characterisation of a series of imine derivatives that incorporate the 2-phenylpyridine (2-ppy) core. These derivatives were used in the cyclometalating reactions of platinum(II) or palladium(II) in order to prepare several complexes with liquid crystalline properties. Depending on the starting materials used as well as the solvents employed, different metal complexes were obtained, some of them showing both liquid crystalline behaviour and luminescence properties at room temperature. It was found that, even if there are two competing coordination sites, the cyclometalation process takes place always at the 2-ppy core with (for Pt) or without (for Pd) the imine bond cleavage. We successfully showed that it is possible to prepare emissive room temperature liquid crystalline materials based on double cyclopalladated heteroleptic complexes by varying the volume fraction of the long flexible alkyl tails on the ancillary benzoylthiourea (BTU) ligands.

  18. Rational serendipity: "undirected" synthesis of a large {MnCu} complex from pre-formed Mn(II) building blocks.

    PubMed

    Frost, Jamie M; Kettles, Fraser J; Wilson, Claire; Murrie, Mark

    2016-11-15

    Use of an aminopolyalcohol-based Mn(II) complex in solvothermal Cu(II) chemistry leads to a rare example of a high nuclearity heterometallic {MnCu} system, in which four Cu(II)(H1Edte) units trap an inner {MnCu(II)} oxide core.

  19. Connecting Core Percolation and Controllability of Complex Networks

    PubMed Central

    Jia, Tao; Pósfai, Márton

    2014-01-01

    Core percolation is a fundamental structural transition in complex networks related to a wide range of important problems. Recent advances have provided us an analytical framework of core percolation in uncorrelated random networks with arbitrary degree distributions. Here we apply the tools in analysis of network controllability. We confirm analytically that the emergence of the bifurcation in control coincides with the formation of the core and the structure of the core determines the control mode of the network. We also derive the analytical expression related to the controllability robustness by extending the deduction in core percolation. These findings help us better understand the interesting interplay between the structural and dynamical properties of complex networks. PMID:24946797

  20. A dinuclear manganese(II) complex with the [Mn(2)(mu-O(2)CCH(3))(3)](+) core: synthesis, structure, characterization, electroinduced transformation, and catalase-like activity.

    PubMed

    Romero, Isabel; Dubois, Lionel; Collomb, Marie-Noëlle; Deronzier, Alain; Latour, Jean-Marc; Pécaut, Jacques

    2002-04-08

    Reactions of Mn(II)(PF(6))(2) and Mn(II)(O(2)CCH(3))(2).4H(2)O with the tridentate facially capping ligand N,N-bis(2-pyridylmethyl)ethylamine (bpea) in ethanol solutions afforded the mononuclear [Mn(II)(bpea)](PF(6))(2) (1) and the new binuclear [Mn(2)(II,II)(mu-O(2)CCH(3))(3)(bpea)(2)](PF(6)) (2) manganese(II) compounds, respectively. Both 1 and 2 were characterized by X-ray crystallographic studies. Complex 1 crystallizes in the monoclinic system, space group P2(1)/n, with a = 11.9288(7) A, b = 22.5424(13) A, c =13.0773(7) A, alpha = 90 degrees, beta = 100.5780(10 degrees ), gamma = 90 degrees, and Z = 4. Crystals of complex 2 are orthorhombic, space group C222(1), with a = 12.5686(16) A, b = 14.4059(16) A, c = 22.515(3) A, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, and Z = 4. The three acetates bridge the two Mn(II) centers in a mu(1,3) syn-syn mode, with a Mn-Mn separation of 3.915 A. A detailed study of the electrochemical behavior of 1 and 2 in CH(3)CN medium has been made. Successive controlled potential oxidations at 0.6 and 0.9 V vs Ag/Ag(+) for a 10 mM solution of 2 allowed the selective and nearly quantitative formation of [Mn(III)(2)(mu-O)(mu-O(2)CCH(3))(2)(bpea)(2)](2+) (3) and [Mn(IV)(2)(mu-O)(2)(mu-O(2)CCH(3))(bpea)(2)](3+) (4), respectively. These results have shown that each substitution of an acetate group by an oxo group is induced by a two-electron oxidation of the corresponding dimanganese complexes. Similar transformations have been obtained if 2 is formed in situ either by direct mixing of Mn(2+) cations, bpea ligand, and CH(3)COO(-) anions with a 1:1:3 stoichiometry or by mixing of 1 and CH(3)COO(-) with a 1:1.5 stoichiometry. Associated electrochemical back-transformations were investigated. 2, 3, and the dimanganese [Mn(III)Mn(IV)(mu-O)(2)(mu-O(2)CCH(3))(bpea)(2)](2+) analogue (5) were also studied for their ability to disproportionate hydrogen peroxide. 2 is far more active compared to 3 and 5. The EPR monitoring of the

  1. Reactivity of copper(II)-alkylperoxo complexes.

    PubMed

    Tano, Tetsuro; Ertem, Mehmed Z; Yamaguchi, Satoru; Kunishita, Atsushi; Sugimoto, Hideki; Fujieda, Nobutaka; Ogura, Takashi; Cramer, Christopher J; Itoh, Shinobu

    2011-10-28

    Copper(II) complexes 1a and 1b, supported by tridentate ligand bpa [bis(2-pyridylmethyl)amine] and tetradentate ligand tpa [tris(2-pyridylmethyl)amine], respectively, react with cumene hydroperoxide (CmOOH) in the presence of triethylamine in CH(3)CN to provide the corresponding copper(II) cumylperoxo complexes 2a and 2b, the formation of which has been confirmed by resonance Raman and ESI-MS analyses using (18)O-labeled CmOOH. UV-vis and ESR spectra as well as DFT calculations indicate that 2a has a 5-coordinate square-pyramidal structure involving CmOO(-) at an equatorial position and one solvent molecule at an axial position at low temperature (-90 °C), whereas a 4-coordinate square-planar structure that has lost the axial solvent ligand is predominant at higher temperatures (above 0 °C). Complex 2b, on the other hand, has a typical trigonal bipyramidal structure with the tripodal tetradentate tpa ligand, where the cumylperoxo ligand occupies an axial position. Both cumylperoxo copper(II) complexes 2a and 2b are fairly stable at ambient temperature, but decompose at a higher temperature (60 °C) in CH(3)CN. Detailed product analyses and DFT studies indicate that the self-decomposition involves O-O bond homolytic cleavage of the peroxo moiety; concomitant hydrogen-atom abstraction from the solvent is partially involved. In the presence of 1,4-cyclohexadiene (CHD), the cumylperoxo complexes react smoothly at 30 °C to give benzene as one product. Detailed product analyses and DFT studies indicate that reaction with CHD involves concerted O-O bond homolytic cleavage and hydrogen-atom abstraction from the substrate, with the oxygen atom directly bonded to the copper(II) ion (proximal oxygen) involved in the C-H bond activation step.

  2. Evaluating the core microbiota in complex communities: A systematic investigation.

    PubMed

    Astudillo-García, Carmen; Bell, James J; Webster, Nicole S; Glasl, Bettina; Jompa, Jamaluddin; Montoya, Jose M; Taylor, Michael W

    2017-04-01

    The study of complex microbial communities poses unique conceptual and analytical challenges, with microbial species potentially numbering in the thousands. With transient or allochthonous microorganisms often adding to this complexity, a 'core' microbiota approach, focusing only on the stable and permanent members of the community, is becoming increasingly popular. Given the various ways of defining a core microbiota, it is prudent to examine whether the definition of the core impacts upon the results obtained. Here we used complex marine sponge microbiotas and undertook a systematic evaluation of the degree to which different factors used to define the core influenced the conclusions. Significant differences in alpha- and beta-diversity were detected using some but not all core definitions. However, findings related to host specificity and environmental quality were largely insensitive to major changes in the core microbiota definition. Furthermore, none of the applied definitions altered our perception of the ecological networks summarising interactions among bacteria within the sponges. These results suggest that, while care should still be taken in interpretation, the core microbiota approach is surprisingly robust, at least for comparing microbiotas of closely related samples.

  3. Oxidative modifications of mitochondria complex II.

    PubMed

    Zhang, Liwen; Kang, Patrick T; Chen, Chwen-Lih; Green, Kari B; Chen, Yeong-Renn

    2013-01-01

    Increased superoxide (O2 (·-)) and nitric oxide (NO) production is a key mechanism of mitochondrial dysfunction in myocardial ischemia/reperfusion injury. In the complex II, oxidative impairment, decreased protein S-glutathionylation, and increased protein tyrosine nitration at the 70 kDa subunit occur in the post-ischemic myocardium (Zhang et al., Biochemistry 49:2529-2539, 2010; Chen et al., J Biol Chem 283:27991-28003, 2008; Chen et al., J Biol Chem 282: 32640-32654, 2007). To gain the deeper insights into ROS-mediated oxidative modifications relevant in myocardial infarction, isolated complex II is subjected to in vitro oxidative modifications with GSSG (to induce cysteine S-glutathionylation) or OONO(-) (to induce tyrosine nitration). Here, we describe the protocol to characterize the specific oxidative modifications at the 70 kDa subunit by nano-LC/MS/MS analysis. We further demonstrate the cellular oxidative modification with protein nitration/S-glutathionylation with immunofluorescence microscopy using the antibodies against 3-nitrotyrosine/glutathione and complex II 70 kDa polypeptide (AbGSC90) in myocytes under conditions of oxidative stress.

  4. Modes of tilting during extensional core complex development.

    PubMed

    Coleman, D S; Walker, J D

    1994-01-14

    Crustal extension and formation of the Mineral Mountains core complex, Utah, involved tilting of the Mineral Mountains batholith and associated faults during hanging wall and footwall deformation. The batholith was folded in the hanging wall of the Beaver Valley fault between 11 and 9 million years ago yielding about 45 degrees of tilt. Subsequently, the batholith was unroofed along the Cave Canyon detachment fault, and the batholith and fault were tilted approximately 40 degrees during footwall uplift. Recognition of deformed dikes beneath the detachment fault establishes the importance of footwall tilt during formation of extensional core complexes and demonstrates that footwall rebound can be an important process during extension.

  5. Structure of the ESCRT-II endosomal trafficking complex.

    PubMed

    Hierro, Aitor; Sun, Ji; Rusnak, Alexander S; Kim, Jaewon; Prag, Gali; Emr, Scott D; Hurley, James H

    2004-09-09

    The multivesicular-body (MVB) pathway delivers transmembrane proteins and lipids to the lumen of the endosome. The multivesicular-body sorting pathway has crucial roles in growth-factor-receptor downregulation, developmental signalling, regulation of the immune response and the budding of certain enveloped viruses such as human immunodeficiency virus. Ubiquitination is a signal for sorting into the MVB pathway, which also requires the functions of three protein complexes, termed ESCRT-I, -II and -III (endosomal sorting complex required for transport). Here we report the crystal structure of the core of the yeast ESCRT-II complex, which contains one molecule of the Vps protein Vps22, the carboxy-terminal domain of Vps36 and two molecules of Vps25, and has the shape of a capital letter 'Y'. The amino-terminal coiled coil of Vps22 and the flexible linker leading to the ubiquitin-binding NZF domain of Vps36 both protrude from the tip of one branch of the 'Y'. Vps22 and Vps36 form nearly equivalent interactions with the two Vps25 molecules at the centre of the 'Y'. The structure suggests how ubiquitinated cargo could be passed between ESCRT components of the MVB pathway through the sequential transfer of ubiquitinated cargo from one complex to the next.

  6. Early Tertiary Anaconda metamorphic core complex, southwestern Montana

    USGS Publications Warehouse

    O'Neill, J. M.; Lonn, J.D.; Lageson, D.R.; Kunk, M.J.

    2004-01-01

    A sinuous zone of gently southeast-dipping low-angle Tertiary normal faults is exposed for 100 km along the eastern margins of the Anaconda and Flint Creek ranges in southwest Montana. Faults in the zone variously place Mesoproterozoic through Paleozoic sedimentary rocks on younger Tertiary granitic rocks or on sedimentary rocks older than the overlying detached rocks. Lower plate rocks are lineated and mylonitic at the main fault and, below the mylonitic front, are cut by mylonitic mesoscopic to microscopic shear zones. The upper plate consists of an imbricate stack of younger-on-older sedimentary rocks that are locally mylonitic at the main, lowermost detachment fault but are characteristically strongly brecciated or broken. Kinematic indicators in the lineated mylonite indicate tectonic transport to the east-southeast. Syntectonic sedimentary breccia and coarse conglomerate derived solely from upper plate rocks were deposited locally on top of hanging-wall rocks in low-lying areas between fault blocks and breccia zones. Muscovite occurs locally as mica fish in mylonitic quartzites at or near the main detachment. The 40Ar/39Ar age spectrum obtained from muscovite in one mylonitic quartzite yielded an age of 47.2 + 0.14 Ma, interpreted to be the age of mylonitization. The fault zone is interpreted as a detachment fault that bounds a metamorphic core complex, here termed the Anaconda metamorphic core complex, similar in age and character to the Bitterroot mylonite that bounds the Bitterroot metamorphic core complex along the Idaho-Montana state line 100 km to the west. The Bitterroot and Anaconda core complexes are likely components of a continuous, tectonically integrated system. Recognition of this core complex expands the region of known early Tertiary brittle-ductile crustal extension eastward into areas of profound Late Cretaceous contractile deformation characterized by complex structural interactions between the overthrust belt and Laramide basement uplifts

  7. Complex foamed aluminum parts as permanent cores in aluminum castings

    SciTech Connect

    Simancik, F.; Schoerghuber, F.

    1998-12-31

    The feasibility of complex shaped aluminum foam parts as permanent cores in aluminum castings has been investigated. The foamed samples were prepared by injection of the foam into sand molds. It turned out that sound castings can be produced if the foam core is properly preheated and/or surface treated before casting. The effect of the foam core on the performance of the casting was evaluated by in compression testing and by measuring structural damping. The gain in the related properties turned out to be much higher than the weight increase of the casting due to the presence of the core. The weight increase may be partially offset through a reduction of the wall-thickness of the shell.

  8. Experimental Breeder Reactor II (EBR-II): Instrumentation for core surveillance

    SciTech Connect

    Christensen, L.J.

    1989-01-01

    EBR-II has operated for 25 years in support of several major programs. During this time period, several of the original, non-replaceable, flow sensors, RDT sensors and thermocouples have failed in the primary system. This has led to the development of new sensors and the use of calculated values using computer models of the plant. It is important for the next generation of LMR reactors to minimize or eliminate the use of non-replaceable sensors. EBR-II is perhaps the best modeled reactor in the world, thanks to a dedicated T-H analysis program. The success of this program relied on excellent measurements of temperature and flow in subassemblies in the core. The instrumented subassemblies of the XX series provided that measurement capability. From this test series, EBR-II calculations showed that the core could withstand a loss-of-flow without scram accident and a loss-of-heat sink without scram accident from full reactor power without core damage. From this, reactor designers can now design with confidence, inherently safe reactors. 11 refs., 8 figs.

  9. Molybdenum complexes of 1,2-bis(diphenylphosphino)benzene. Mononuclear molybdenum(II) species formed by facile metal-metal bond cleavage of the (Mo-/sup 4/Mo)/sup 4+/ core

    SciTech Connect

    Bakir, M.; Cotton, F.A.; Cudahy, M.M.; Simpson, C.Q.; Smith, T.J.; Vogel, E.F.; Walton, R.A.

    1988-07-27

    The quadruply bonded dimolybdenum(II) complexes K/sub 4/Mo/sub 2/Cl/sub 8/, (NH/sub 4/)/sub 5/MoCl/sub 9/ /times/ H/sub 2/O, and (NH/sub 4/)/sub 4/Mo/sub 2/Br/sub 8/ react with 1,2-C/sub 6/H/sub 4/(PPh/sub 2/)/sub 2/(dppbe) in methanol at room temperature to afford /alpha/-Mo/sub 2/X/sub 4/(dppbe)/sub 2/ complexes (X = Cl, Br), which do not isomerize to the /beta/ isomers. Under more forcing reactions conditions (refluxing 1-propanol), these same reactions give mononuclear trans-MoX/sub 2/(dppbe)/sub 2/ in good yield (ca. 50%) together with some (MoOX(dppbe)/sub 2/)X /times/ nH/sub 2/O. An alternative synthetic strategy for the preparation of /alpha/-Mo/sub 2/X/sub 4/(dppbe)/sub 2/ involves the reaction of Mo/sub 2/(O/sub 2/CCH/sub 3/)/sub 4/ with dppbe and Me/sub 3/SiX in THF. The compound MoCl/sub 2/(dppbe)/sub 2/ forms crystals in space group P2/sub 1//n, with the following unit cell parameters: a = 10.884 (2) /angstrom/, b = 12.753 (2) /angstrom/, c = 18.141 (4) /angstrom/, /beta/ = 91.43 (2)/degree/, V = 2517 (2) /angstrom//sup 3/, and Z = 2. The centrosymmetric trans molecule has Mo-Cl = 2.410 (1) /angstrom/, Mo-P = 2.481 (1), 2.511 (1) /angstrom/, and P-Mo-P(intra-ring) = 78.68 (4)/degree/. 25 refs., 1 fig., 4 tabs.

  10. Deactivation of the EBR-II complex

    SciTech Connect

    Michelbacher, J A; Earle, O K; Henslee, S P; Wells, P B; Zahn, T P

    1996-01-01

    In January of 1994, the Department of Energy mandated the termination of the Integral Fast Reactor (IFR) Program, effective October 1, 1994. To comply with this decision, Argonne National Laboratory-West (ANL-W) prepared a plan providing detailed requirements to place the Experimental Breeder Reactor-II (EBR-II) in a radiologically and industrially safe condition, including removal of all irradiated fuel assemblies from the reactor plant, and removal and stabilization of the primary and secondary sodium, a liquid metal used to transfer heat within the reactor plant. The ultimate goal of the deactivation process is to place the EBR-II complex in a stable condition until a decontamination and decommissioning (D and D) plan can be prepared, thereby minimizing requirements for maintenance and surveillance and maximizing the amount of time for radioactive decay. The final closure state will be achieved in full compliance with federal, state and local environmental, safety, and health regulations and requirements. The decision to delay the development of a detailed D and D plan has necessitated this current action.

  11. FINDING THE FIRST COSMIC EXPLOSIONS. II. CORE-COLLAPSE SUPERNOVAE

    SciTech Connect

    Whalen, Daniel J.; Joggerst, Candace C.; Fryer, Chris L.; Stiavelli, Massimo; Heger, Alexander; Holz, Daniel E.

    2013-05-01

    Understanding the properties of Population III (Pop III) stars is prerequisite to elucidating the nature of primeval galaxies, the chemical enrichment and reionization of the early intergalactic medium, and the origin of supermassive black holes. While the primordial initial mass function (IMF) remains unknown, recent evidence from numerical simulations and stellar archaeology suggests that some Pop III stars may have had lower masses than previously thought, 15-50 M{sub Sun} in addition to 50-500 M{sub Sun }. The detection of Pop III supernovae (SNe) by JWST, WFIRST, or the TMT could directly probe the primordial IMF for the first time. We present numerical simulations of 15-40 M{sub Sun} Pop III core-collapse SNe performed with the Los Alamos radiation hydrodynamics code RAGE. We find that they will be visible in the earliest galaxies out to z {approx} 10-15, tracing their star formation rates and in some cases revealing their positions on the sky. Since the central engines of Pop III and solar-metallicity core-collapse SNe are quite similar, future detection of any Type II SNe by next-generation NIR instruments will in general be limited to this epoch.

  12. Deactivation of the EBR-II complex

    SciTech Connect

    Michelbacher, J.A.; Earle, O.K.; Henslee, S.P.

    1997-12-31

    In January of 1994, the Department of Energy mandated the termination of the Integral Fast Reactor (IFR) Program, effective October 1, 1994. To comply with this decision, Argonne National Laboratory-West (ANL-W) prepared a plan providing detailed requirements to place the Experimental Breeder Reactor-II (EBR-II) in a radiologically and industrially safe condition, including removal of all irradiated fuel assemblies from the reactor plant, and removal and stabilization of the primary and secondary sodium, a liquid metal used to transfer heat within the reactor plant. The ultimate goal of the deactivation process is to place the EBR-II complex in a stable condition until a decontamination and decommissioning (D&D) plan can be prepared, thereby minimizing requirements for maintenance and surveillance and maximizing the amount of time for radioactive decay. The final closure state will be achieved in full compliance with federal, state and local environmental, safety, and health regulations and requirements. The decision to delay the development of a detailed D&D plan has necessitated this current action. The EBR-II is a pool-type reactor. The primary system contains approximately 87,000 gallons of sodium, while the secondary system has 13,000 gallons. In order to properly dispose of the sodium in compliance with the Resource Conservation and Recovery Act (RCRA), a facility has been built to react the sodium to a dry carbonate powder in a two stage process. Deactivation of a liquid metal fast breeder reactor (LMFBR) presents unique concerns. Residual amounts of sodium remaining in the primary and secondary systems must be either reacted or inerted to preclude future concerns with sodium-air reactions that generate explosive mixtures of hydrogen and leave corrosive compounds. Residual amounts of sodium on components will effectively {open_quotes}solder{close_quotes} components in place, making future operation or removal unfeasible.

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

    PubMed

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

    2015-08-24

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

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

    PubMed

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

    2013-10-07

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

  15. The synthesis, design and applications of lanthanide cored complexes

    NASA Astrophysics Data System (ADS)

    Phelan, Gregory David

    Novel luminescent materials based on lanthanide cored complexes have been designed and synthesized. The complexes consist of a beta-diketone ligand chelated to a lanthanide metal such as europium or gadolinium. A series of beta-diketone ligands were designed and synthesized. The ligands consist of a polycyclic aromatic sensitizer, phenanthrene, and a second functional group. The second groups consisted of another unit of phenanthrene, a dendritic structure, or a fluorinated alkyl chain. The europium complexes have been incorporated into organic light emitting devices that have a major emission at 615 nm and a maximum brightness of 300 cd/m2. The gadolinium complexes were used to dope into the resulting organic light emitting devices to help improve the efficiency of the device. The use of the gadolinium complexes results in a 25 fold increase in efficiency.

  16. COMPLEX MOLECULES TOWARD LOW-MASS PROTOSTARS: THE SERPENS CORE

    SciTech Connect

    Oeberg, Karin I.; Van der Marel, Nienke; Kristensen, Lars E.; Van Dishoeck, Ewine F.

    2011-10-10

    Gas-phase complex organic molecules are commonly detected toward high-mass protostellar hot cores. Detections toward low-mass protostars and outflows are comparatively rare, and a larger sample is the key to investigate how the chemistry responds to its environment. Guided by the prediction that complex organic molecules form in CH{sub 3}OH-rich ices and thermally or non-thermally evaporate with CH{sub 3}OH, we have identified three sight lines in the Serpens core-SMM1, SMM4, and SMM4-W-which are likely to be rich in complex organics. Using the IRAM 30 m telescope, narrow lines (FWHM of 1-2 km s{sup -1}) of CH{sub 3}CHO and CH{sub 3}OCH{sub 3} are detected toward all sources, HCOOCH{sub 3} toward SMM1 and SMM4-W, and C{sub 2}H{sub 5}OH not at all. Beam-averaged abundances of individual complex organics range between 0.6% and 10% with respect to CH{sub 3}OH when the CH{sub 3}OH rotational temperature is applied. The summed complex organic abundances also vary by an order of magnitude, with the richest chemistry toward the most luminous protostar SMM1. The range of abundances compare well with other beam-averaged observations of low-mass sources. Complex organic abundances are of the same order of magnitude toward low-mass protostars and high-mass hot cores, but HCOOCH{sub 3} is relatively more important toward low-mass protostars. This is consistent with a sequential ice photochemistry, dominated by CHO-containing products at low temperatures and early times.

  17. Gravitational instability of mantle lithosphere and core complexes

    NASA Astrophysics Data System (ADS)

    Molnar, Peter

    2015-03-01

    For a wide range of viscosity structures, convergent and downward flow of the mantle lithosphere during the growth of gravitational instability induces not only thickening of overlying crust but also concurrent horizontal extension in the upper crust. Such extension, if it occurred in the Earth, would include normal faulting of the upper crust above a region of horizontal shortening in the lower crust and uppermost mantle. Convergent flow in the lower crust would also create shear stress on horizontal planes and localized upward flow of the lower crust. These features—extension of upper crust and exhumation of strained lower crust—characterize metamorphic core complexes exposed in regions of normal to thick continental crust. Thus, convergent flow and downwelling mantle lithosphere might contribute to the development of core complexes, at least in some settings. If horizontal shortening and crustal thickening at depth do occur simultaneously with normal faulting at the surface of the Earth today, evidence of this process does not seem obvious, but perhaps it has occurred concurrently with widespread regional crustal extension in places like the Basin and Range Province, Tibet, the Pamir, or the Aegean. If such mantle flow does participate in the development of core complexes, a weak lower crust might not be a prerequisite for their formation.

  18. Footwall rotation in an oceanic core complex quantified using reoriented Integrated Ocean Drilling Program core samples

    NASA Astrophysics Data System (ADS)

    Morris, A.; Gee, J. S.; Pressling, N.; John, B. E.; MacLeod, C. J.; Grimes, C. B.; Searle, R. C.

    2009-09-01

    Oceanic core complexes expose lower crustal and upper mantle rocks on the seafloor by tectonic unroofing in the footwalls of large-slip detachment faults. The common occurrence of these structures in slow and ultra-slow spread oceanic crust suggests that they accommodate a significant component of plate divergence. However, the subsurface geometry of detachment faults in oceanic core complexes remains unclear. Competing models involve either: (a) displacement on planar, low-angle faults with little tectonic rotation; or (b) progressive shallowing by rotation of initially steeply dipping faults as a result of flexural unloading (the "rolling-hinge" model). We address this debate using palaeomagnetic remanences as markers for tectonic rotation within a unique 1.4 km long footwall section of gabbroic rocks recovered by Integrated Ocean Drilling Program (IODP) sampling at Atlantis Massif oceanic core complex on the Mid-Atlantic Ridge (MAR). These rocks contain a complex record of multipolarity magnetizations that are unrelated to alteration and igneous stratigraphy in the sampled section and are inferred to result from progressive cooling of the footwall section over geomagnetic polarity chrons C1r.2r, C1r.1n (Jaramillo) and C1r.1r. For the first time we have independently reoriented drill-core samples of lower crustal gabbros, that were initially azimuthally unconstrained, to a true geographic reference frame by correlating structures in individual core pieces with those identified from oriented imagery of the borehole wall. This allows reorientation of the palaeomagnetic data, placing far more rigorous constraints on the tectonic history than those possible using only palaeomagnetic inclination data. Analysis of the reoriented high temperature reversed component of magnetization indicates a 46° ± 6° anticlockwise rotation of the footwall around a MAR-parallel horizontal axis trending 011° ± 6°. Reoriented lower temperature components of normal and reversed

  19. Heptacopper(II) and dicopper(II)-adenine complexes: synthesis, structural characterization, and magnetic properties

    DOE PAGES

    Leite Ferreira, B. J. M.; Brandão, Paula; Dos Santos, A. M.; ...

    2015-07-13

    The syntheses, crystal structures, and magnetic properties of two new copper(II) complexes with molecular formulas [Cu7(μ2-OH2)6(μ3-O)6(adenine)6(NO3)26H2O (1) and [Cu2(μ2-H2O)2(adenine)2(H2O)4](NO3)42H2O (2) are reported. We composed the heptanuclear compound of a central octahedral CuO6 core sharing edges with six adjacent copper octahedra. In 2, the copper octahedra shares one equatorial edge. In both compounds, these basic copper cluster units are further linked by water bridges and bridging adenine ligands through N3 and N9 donors. All copper(II) centers exhibit Jahn-Teller distorted octahedral coordination characteristic of a d9 center. Our study of the magnetic properties of the heptacopper complex revealed a dominant ferromagnetic intra-clustermore » interaction, while the dicopper complex exhibits antiferromagnetic intra-dimer interactions with weakly ferromagnetic inter-dimer interaction.« less

  20. Heptacopper(II) and dicopper(II)-adenine complexes: synthesis, structural characterization, and magnetic properties

    SciTech Connect

    Leite Ferreira, B. J. M.; Brandão, Paula; Dos Santos, A. M.; Gai, Z.; Cruz, C.; Reis, M. S.; Santos, T. M.; Félix, V.

    2015-07-13

    The syntheses, crystal structures, and magnetic properties of two new copper(II) complexes with molecular formulas [Cu72-OH2)63-O)6(adenine)6(NO3)26H2O (1) and [Cu22-H2O)2(adenine)2(H2O)4](NO3)42H2O (2) are reported. We composed the heptanuclear compound of a central octahedral CuO6 core sharing edges with six adjacent copper octahedra. In 2, the copper octahedra shares one equatorial edge. In both compounds, these basic copper cluster units are further linked by water bridges and bridging adenine ligands through N3 and N9 donors. All copper(II) centers exhibit Jahn-Teller distorted octahedral coordination characteristic of a d9 center. Our study of the magnetic properties of the heptacopper complex revealed a dominant ferromagnetic intra-cluster interaction, while the dicopper complex exhibits antiferromagnetic intra-dimer interactions with weakly ferromagnetic inter-dimer interaction.

  1. Model Compounds for Iron Proteins. Structures and Magnetic, Spectroscopic, and Redox Properties of Fe(III)M(II) and [Co(III)Fe(III)](2)O Complexes with (&mgr;-Carboxylato)bis(&mgr;-phenoxo)dimetalate and (&mgr;-Oxo)diiron(III) Cores.

    PubMed

    Dutta, Sujit K.; Werner, Rüdiger; Flörke, Ulrich; Mohanta, Sasankasekhar; Nanda, Kausik K.; Haase, Wolfgang; Nag, Kamalaksha

    1996-04-10

    A series of heterobimetallic complexes of the type [Fe(III)M(II)L(&mgr;-OAc)(OAc)(H(2)O)](ClO(4)).nH(2)O (2-5) and [{Fe(III)Co(III)L(&mgr;-OAc)(OAc)}(2)(&mgr;-O)](ClO(4))(2).3H(2)O (6) where H(2)L is a tetraaminodiphenol macrocyclic ligand and M(II) = Zn(2), Ni(3), Co(4), and Mn(5) have been synthesized and characterized. The (1)H NMR spectrum of 6 exhibits all the resonances between 1 and 12 ppm. The IR and UV-vis spectra of 2-5 indicate that in all the cases the metal ions have similar coordination environments. A disordered crystal structure determined for 3 reveals the presence of a (&mgr;-acetate)bis(&mgr;-phenoxide)-Ni(II)Fe(III) core, in which the two metal ions have 6-fold coordination geometry and each have two amino nitrogens and two phenolate oxygens as the in-plane donors; aside from the axial bridging acetate, the sixth coordination site of nickel(II) is occupied by the unidentate acetate and that of iron(III) by a water molecule. The crystal structure determination of 6 shows that the two heterobinuclear Co(III)Fe(III) units are bound by an Fe-O-Fe linkage. 6 crystallizes in the orthorhombic space group Ibca with a = 17.577(4) Å, b = 27.282(7) Å, c = 28.647(6) Å, and Z = 8. The two iron(III) centers in 6 are strongly antiferromagnetically coupled, J = -100 cm(-1) (H = -2JS(1).S(2)), whereas the other two S(1) = S(2) = (5)/(2) systems, viz. [Fe(2)(III)(HL)(2)(&mgr;-OH)(2)](ClO(4))(2) (1) and the Fe(III)Mn(II) complex (5), exhibit weak antiferromagnetic exchange coupling with J = -4.5 cm(-1) (1) and -1.8 cm(-1) (5). The Fe(III)Ni(II) (3) and Fe(III)Co(II) (4) systems, however, exhibit weak ferromagnetic behavior with J = 1.7 cm(-1) (3) and 4.2 cm(-1) (4). The iron(III) center in 2-5 exhibits quasi-reversible redox behavior between -0.44 and -0.48 V vs Ag/AgCl associated with reduction to iron(II). The oxidation of cobalt(II) in 4 occurs quasi-reversibly at 0.74 V, while both nickel(II) and manganese(II) in 3 and 5 undergo irreversible oxidation at 0

  2. THE ORIGIN OF COMPLEX ORGANIC MOLECULES IN PRESTELLAR CORES

    SciTech Connect

    Vastel, C.; Ceccarelli, C.; Lefloch, B.; Bachiller, R.

    2014-11-01

    Complex organic molecules (COMs) have been detected in a variety of environments including cold prestellar cores. Given the low temperatures of these objects, these detections challenge existing models. We report here new observations toward the prestellar core L1544. They are based on an unbiased spectral survey of the 3 mm band at the IRAM 30 m telescope as part of the Large Program ASAI. The observations allow us to provide a full census of the oxygen-bearing COMs in this source. We detected tricarbon monoxide, methanol, acetaldehyde, formic acid, ketene, and propyne with abundances varying from 5 × 10{sup –11} to 6 × 10{sup –9}. The non-LTE analysis of the methanol lines shows that they are likely emitted at the border of the core at a radius of ∼8000 AU, where T ∼ 10 K and n {sub H{sub 2}} ∼2 × 10{sup 4} cm{sup –3}. Previous works have shown that water vapor is enhanced in the same region because of the photodesorption of water ices. We propose that a non-thermal desorption mechanism is also responsible for the observed emission of methanol and COMs from the same layer. The desorbed oxygen and a small amount of desorbed methanol and ethene are enough to reproduce the abundances of tricarbon monoxide, methanol, acetaldehyde, and ketene measured in L1544. These new findings open the possibility that COMs in prestellar cores originate in a similar outer layer rather than in the dense inner cores, as previously assumed, and that their formation is driven by the non-thermally desorbed species.

  3. Antibacterial Co(II), Cu(II), Ni(II) and Zn(II) Complexes of Thiadiazoles Schiff Bases

    PubMed Central

    Jaffery, Maimoon F.; Supuran, Claudiu T.

    2001-01-01

    Schiff bases were obtained by condensation of 2-amino-l,3,4-thiadiazole with 5-substituted-salicylaldehydes which were further used to obtain complexes of the type [M(L)2]Cl2, where M=Co(II), Cu(II), Ni(II) or Zn(II). The new compounds described here have been characterized by physical, spectral and analytical data, and have been screened for antibacterial activity against several bacterial strains such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The antibacterial potency of these Schiff bases increased upon chelation/complexation, against the tested bacterial species, opening new aproaches in the fight against antibiotic resistant strains. PMID:18475981

  4. Heteroleptic bis(dipyrrinato)copper(II) and nickel(II) complexes.

    PubMed

    Toyoda, Ryojun; Tsuchiya, Mizuho; Sakamoto, Ryota; Matsuoka, Ryota; Wu, Kuo-Hui; Hattori, Yohei; Nishihara, Hiroshi

    2015-09-14

    Heteroleptic bis(dipyrrinato)copper(II) and nickel(II) complexes are synthesized. Their structures are determined by X-ray diffraction analysis, and their properties are investigated by using cyclic voltammetry, chronocoulometry, and UV/vis absorption spectroscopy.

  5. Nickel(II) and copper(II) complexes with humic acid anions and their derivatives

    SciTech Connect

    Ryabova, I.N.

    2008-01-15

    Complexation of Ni(II) and Cu(II) in aqueous solutions with anions of humic acids, extracted from naturally oxidized coal, and with their hydroxymethyl derivatives is studied spectrophotometrically and potentiometrically. The complexation stoichiometry and the stability constants of the complexes are determined.

  6. Dense cores in the dark cloud complex LDN 1188

    NASA Astrophysics Data System (ADS)

    Verebélyi , E.; Könyves, V.; Nikolić, S.; Kiss, Cs.; Moór, A.; Ábrahám, P.; Kun, M.

    2013-11-01

    We present a molecular line emission study of the LDN 1188 dark cloud complex located in Cepheus. In this work we focused on the densest parts of the cloud and on the close neighbourhood of infrared point sources. We made ammonia mapping with the Effelsberg 100 m radio telescope and identified 3 dense cores. CS(1-0), CS(2-1) and HCO+(1-0) measurements performed with the Onsala 20 m telescope revealed the distribution of dense molecular material. The molecular line measurements were supplemented by mapping the dust emission at 1.2 mm in some selected directions using the IRAM 30 m telescope. With these data we could work out a likely evolutionary sequence in this dark cloud complex.

  7. Spectral, IR and magnetic studies of Mn(II), Co(II), Ni(II) and Cu(II) complexes with pyrrole-2-carboxyaldehyde thiosemicarbazone (L).

    PubMed

    Chandra, Sulekh; Kumar, Anil

    2007-11-01

    Mn(II), Co(II), Ni(II) and Cu(II) complexes are synthesized with thiosemicarbazone (L) derived from pyrrole-2-carboxyaldehyde. These complexes are characterized by elemental analysis, molar conductance, magnetic susceptibility measurement, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO indicates that the complexes are non-electrolyte except Co(L)2(NO3)2 and Ni(L)2(NO3)2 complexes which are 1:2 electrolyte. All the complexes are of high-spin type. On the basis of spectral studies an octahedral geometry may be assigned for Mn(II), Co(II) and Ni(II) complexes except Co(L)2(NO3)2 and Ni(L)2(NO3)2 which are of tetrahedral geometry. A tetragonal geometry may be suggested for Cu(II) complexes.

  8. Ii Chain Controls the Transport of Major Histocompatibility Complex Class II Molecules to and from Lysosomes

    PubMed Central

    Brachet, Valérie; Raposo, Graça; Amigorena, Sebastian; Mellman, Ira

    1997-01-01

    Major histocompatibility complex class II molecules are synthesized as a nonameric complex consisting of three αβ dimers associated with a trimer of invariant (Ii) chains. After exiting the TGN, a targeting signal in the Ii chain cytoplasmic domain directs the complex to endosomes where Ii chain is proteolytically processed and removed, allowing class II molecules to bind antigenic peptides before reaching the cell surface. Ii chain dissociation and peptide binding are thought to occur in one or more postendosomal sites related either to endosomes (designated CIIV) or to lysosomes (designated MIIC). We now find that in addition to initially targeting αβ dimers to endosomes, Ii chain regulates the subsequent transport of class II molecules. Under normal conditions, murine A20 B cells transport all of their newly synthesized class II I-Ab αβ dimers to the plasma membrane with little if any reaching lysosomal compartments. Inhibition of Ii processing by the cysteine/serine protease inhibitor leupeptin, however, blocked transport to the cell surface and caused a dramatic but selective accumulation of I-Ab class II molecules in lysosomes. In leupeptin, I-Ab dimers formed stable complexes with a 10-kD NH2-terminal Ii chain fragment (Ii-p10), normally a transient intermediate in Ii chain processing. Upon removal of leupeptin, Ii-p10 was degraded and released, I-Ab dimers bound antigenic peptides, and the peptide-loaded dimers were transported slowly from lysosomes to the plasma membrane. Our results suggest that alterations in the rate or efficiency of Ii chain processing can alter the postendosomal sorting of class II molecules, resulting in the increased accumulation of αβ dimers in lysosome-like MIIC. Thus, simple differences in Ii chain processing may account for the highly variable amounts of class II found in lysosomal compartments of different cell types or at different developmental stages. PMID:9105036

  9. A pentanuclear lead(II) complex based on a strapped porphyrin with three different coordination modes.

    PubMed

    Le Gac, Stéphane; Furet, Eric; Roisnel, Thierry; Hijazi, Ismail; Halet, Jean-François; Boitrel, Bernard

    2014-10-06

    We have previously described Pb(II) and Bi(III) bimetallic complexes with overhanging carboxylic acid strapped porphyrins in which one metal ion is bound to the N-core ("out-of-plane", OOP), whereas the second one is bound to the strap ("hanging-atop", HAT). In such complexes, the hemidirected coordination sphere of a HAT Pb(II) cation provides sufficient space for an additional binding of a neutral ligand (e.g., DMSO). Interestingly, investigations of the HAT metal coordination mode in a single strap porphyrin show that a HAT Pb(II) can also interact via intermolecular coordination bonds, allowing the self-assembly of two bimetallic complexes. In the pentanuclear Pb(II) complex we are describing in this Article, three different coordination modes were found. The OOP Pb(II) remains inert toward the supramolecular assembling process, whereas the HAT Pb(II) cation, in addition to its intramolecular carboxylate and regular exogenous acetate groups, coordinates an additional exogenous acetate. These two acetates are shared with a third lead(II) cation featuring a holo-directed coordination sphere, from which a centro-symmetric complex is assembled. Density functional theory calculations show some electron-density pockets in the vicinity of the hemidirected HAT Pb(II) atoms, which are associated with the presence of a stereochemically active lone pair of electrons. On the basis of the comparison with other HAT Pb(II) and Bi(III) systems, the "volume" of this lone pair correlates well with the bond distance distributions and the number of the proximal oxygen atoms tethered to the post-transition metal cation. It thus follows the order 6-coordinate Bi(III) > 6-coordinate Pb(II) > 5-coordinate Pb(II).

  10. Spectroscopic and mycological studies of Co(II), Ni(II) and Cu(II) complexes with 4-aminoantipyrine derivative

    NASA Astrophysics Data System (ADS)

    Sharma, Amit Kumar; Chandra, Sulekh

    2011-10-01

    Complexes of the type [M(L)X 2], where M = Co(II), Ni(II) and Cu(II), have been synthesized with novel NO-donor Schiff's base ligand, 1,4-diformylpiperazine bis(4-imino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) which is obtained by the acid catalyzed condensation of 1,4-diformylpiperazine with 4-aminoantipyrine. The elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, UV, NMR, mass and EPR studies of the compounds led to the conclusion that the ligand acts as tetradentate chelate. The Schiff's base ligand forms hexacoordinated complexes having octahedral geometry for Ni(II) and tetragonal geometry for Co(II) and Cu(II) complexes. The mycological studies of the compounds were examined against the several opportunistic pathogens, i.e., Alternaria brassicae, Aspergillus niger and Fusarium oxysporum. The Cu(II) complexes were found to have most fungicidal behavior.

  11. REVIEW ARTICLE: Geophysical signatures of oceanic core complexes

    NASA Astrophysics Data System (ADS)

    Blackman, Donna K.; Canales, J. Pablo; Harding, Alistair

    2009-08-01

    Oceanic core complexes (OCCs) provide access to intrusive and ultramafic sections of young lithosphere and their structure and evolution contain clues about how the balance between magmatism and faulting controls the style of rifting that may dominate in a portion of a spreading centre for Myr timescales. Initial models of the development of OCCs depended strongly on insights available from continental core complexes and from seafloor mapping. While these frameworks have been useful in guiding a broader scope of studies and determining the extent of OCC formation along slow spreading ridges, as we summarize herein, results from the past decade highlight the need to reassess the hypothesis that reduced magma supply is a driver of long-lived detachment faulting. The aim of this paper is to review the available geophysical constraints on OCC structure and to look at what aspects of current models are constrained or required by the data. We consider sonar data (morphology and backscatter), gravity, magnetics, borehole geophysics and seismic reflection. Additional emphasis is placed on seismic velocity results (refraction) since this is where deviations from normal crustal accretion should be most readily quantified. However, as with gravity and magnetic studies at OCCs, ambiguities are inherent in seismic interpretation, including within some processing/analysis steps. We briefly discuss some of these issues for each data type. Progress in understanding the shallow structure of OCCs (within ~1 km of the seafloor) is considerable. Firm constraints on deeper structure, particularly characterization of the transition from dominantly mafic rock (and/or altered ultramafic rock) to dominantly fresh mantle peridotite, are not currently in hand. There is limited information on the structure and composition of the conjugate lithosphere accreted to the opposite plate while an OCC forms, commonly on the inside corner of a ridge-offset intersection. These gaps preclude full

  12. Supramolecular control of a mononuclear biomimetic copper(II) center: bowl complexes vs funnel complexes.

    PubMed

    Gout, Jérôme; Višnjevac, Aleksandar; Rat, Stéphanie; Parrot, Arnaud; Hessani, Assia; Bistri, Olivia; Le Poul, Nicolas; Le Mest, Yves; Reinaud, Olivia

    2014-06-16

    Modeling the mononuclear site of copper enzymes is important for a better understanding of the factors controlling the reactivity of the metal center. A major difficulty stems from the difficult control of the nuclearity while maintaining free sites open to coordination of exogenous ligands. A supramolecular approach consists in associating a hydrophobic cavity to a tripodal ligand that will define the coordination spheres as well as access to the metal ion. Here, we describe the synthesis of a bowl Cu(II) complex based on the resorcinarene scaffold. This study supplements a previous work on Cu(I) coordination. It provides a complete picture of the cavity-copper system in its two oxidation states. The first XRD structure of such a bowl complex was obtained, evidencing a 5-coordinate Cu(II) ion with the three imidazole donors bound to the metal (two in the base of the pyramid, one in the apical position) and with an acetate anion, completing the base of the pyramid, and deeply included in the bowl. Solution studies conducted by EPR and UV-vis absorption spectroscopies as well as cyclic voltammetry highlighted interaction with coordinating solvents, various carboxylates that can sit either in the endo or in the exo position depending on their size as well as possible stabilization of hydroxo species in a mononuclear state. A comparison of the binding and redox properties of the bowl complex with funnel complexes based on the calix[6]arene core further highlights the importance of supramolecular features defining the first, second, and third coordination sphere for control of the metal ion.

  13. Calix[4]arene based chemosensor for selective complexation of Cd(II) and Cu(II)

    NASA Astrophysics Data System (ADS)

    Qazi, Mansoor Ahmed; Qureshi, Imdadullah; Memon, Shahabuddin

    2010-06-01

    The present article describes synthesis, characterization and a detailed complexation study of calix[4]arene based chemosensor ( 4) bearing two anthracenyl units as signaling groups on its coordination sphere. The complex formation ability of 4 toward selected transition metals such as Cd(II), Co(II), Cu(II), Ni(II) and Pb(II) has been investigated by UV-visible spectroscopy. Assessment of results reveal that the chemosensor is selective toward Cd(II) and Cu(II). The FT-IR spectroscopic method was applied for further confirmation of the complexation phenomenon. Besides this, a study regarding interference of other metals on complex formation in solution has also supported the efficient binding preference of 4 for Cd(II) and Cu(II). From the results it has been concluded that 4 has compatible coordination sphere to accommodate these metals. The similarities and differences revealed that being soft nature of both metals and because of diagonal relationship in the periodic table their coordination behavior toward N/O-donor ligand may be treated as a test on possibility of the Cu(II) ions to be displaced by Cd(II). The study certainly will help in understanding the hazards of Cd(II) in biological systems.

  14. The vibrational spectra of the Ni(II) and Cu(II) complexes with oxamic hydrazide

    NASA Astrophysics Data System (ADS)

    Quaeyhaegens, Frank; Hofmans, Hendrik; Desseyn, H. O.

    The infrared-, Raman- and u.v./vis spectra as well as the thermal analysis ofthe Ni(II)and Cu(II) complexes with oxamic hydrazide (H 2NCOCONHNH 2) are discussed. We assume 2/1 planar complexes and a coordination via the four amide nitrogen atoms as visualised in Fig. 1.

  15. Passive Seismic Imaging of the Ruby Mountains Core Complex, Nevada

    NASA Astrophysics Data System (ADS)

    Litherland, M.; Klemperer, S. L.

    2015-12-01

    We investigate the deep crustal structure of the Ruby Mountains Core Complex (RMCC) using data collected from the Ruby Mountains Seismic Experiment. This project, part of the Earthscope Flexible Array program, deployed 50 passive broadband stations across the RMCC from 2010 to 2012. Previous investigations of the area have included extensive surface mapping and active seismic profiles across the surrounding basins, but better imaging beneath the mountain range is needed to understand the tectonic processes that formed the RMCC. The RMCC exhibits typical core-complex structure of deep crustal rocks exhumed to the surface beneath a gently dipping detachment, with a thick mylonitic shear zone directly underlying the detachment. In the RMCC, the westward dip of the detachment, the ~1km-thick mylonite zone formed in the Paleogene, and a south-to-north increase in metamorphic grade provide targets for imaging. We used common conversion point stacking of receiver functions to produce 3 profiles of structural discontinuities beneath the RMCC: one along the axis of the RMCC, and two crossing lines, one in the northern RMCC, and one in the southern part of the range. Due to the deep sedimentary basins surrounding the RMCC, various de-multiple processes were required to reduce the effects of basin reverberations. To better constrain the velocity structure of the area, we used ambient-noise tomography, and finally, we produced a joint inversion of our receiver functions and ambient-noise data. We observe a mostly flat Moho at about 30 km depth beneath the RMCC that dips slightly to the south, with faint mid-crustal converters that also dip south at ~30°. In the southern RMCC, the Moho dips ~20° westward, but this is not observed in the northern RMCC. This suggests that much of the exhumation involved in the RMCC formation likely involved ductile flow that left a mostly flat Moho, but more recent processes also may have left observable changes in lower-crustal structure.

  16. XAFS studies of Pb(II)-chloro and Hg(II)-chloro ternary complexes on goethite

    USGS Publications Warehouse

    Bargar, J.R.; Persson, Petra; Brown, Gordon E.

    1997-01-01

    EXAFS spectroscopy was used to study Pb(II) and Hg(II) adsorption complexes on goethite (??-FeOOH) in the presence of Cl-. At pH 7, the dominant Pb(II) species are bonded to edges of FeO6 octahedra and are similar to complexes that occur in the absence of Cl-. At pH ??? 6, Pb(II)-chloro ternary complexes predominate and are bonded to corners of FeO6 octahedra. At pH 6.5, linear Hg(OH)Cl ternary complexes predominate that are bonded to goethite through surface oxygens in a bent Hg-O-Fe geometry. In the absence of Cl-, the Hg(II) surface complexes retain this basic geometry, but an OH group replaces the chloride ion in the first coordination shell.

  17. Amino-functionalized core-shell magnetic mesoporous composite microspheres for Pb(II) and Cd(II) removal.

    PubMed

    Tang, Yulin; Liang, Song; Wang, Juntao; Yu, Shuili; Wang, Yilong

    2013-04-01

    Amino-functionalized Fe3O4@mesoporous SiO2 core-shell composite microspheres NH2-MS in created in multiple synthesis steps have been investigated for Pb(II) and Cd(II) adsorption. The microspheres were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), N2 adsorption-desorption, zeta potential measurements and vibrating sample magnetometer. Batch adsorption tests indicated that NH2-MS exhibited higher adsorption affinity toward Pb(II) and Cd(II) than MS did. The Langmuir model could fit the adsorption isotherm very well with maximum adsorption capacity of 128.21 and 51.81 mg/g for Pb(II) and Cd(II), respectively, implying that adsorption processes involved monolayer adsorption. Pb(II) and Cd(II) adsorption could be well described by the pseudo second-order kinetics model, and was found to be strongly dependent on pH and humic acid. The Pb(II)- and Cd(II)-loaded microspheres were effectively desorbed using 0.01 mol/L HCl or EDTA solution. NH2-MS have promise for use as adsorbents in the removal of Pb(II) and Cd(II) in wastewater treatment processes.

  18. Structures of polynuclear complexes of palladium(II) and platinum(II) formed by slow hydrolysis in acidic aqueous solution.

    PubMed

    Torapava, Natallia; Elding, Lars I; Mändar, Hugo; Roosalu, Kaspar; Persson, Ingmar

    2013-06-07

    The aqua ions of palladium(II) and platinum(II) undergo extremely slow hydrolysis in strongly acidic aqueous solution, resulting in polynuclear complexes. The size and structures of these species have been determined by EXAFS and small angle X-ray scattering, SAXS. For palladium(II), the EXAFS data show that the Pd-O and Pd···Pd distances are identical to those of crystalline palladium(II) oxide, but the intensities of the Pd···Pd distances in the Fourier transform at 3.04 and 3.42 Å are significantly lower compared to those of crystalline PdO. Furthermore, no Pd···Pd distances beyond 4 Å are observed. These observations strongly indicate that the polynuclear palladium(II) complexes are oxido- and hydroxido-bridged species with the same core structure as solid palladium(II) oxide. Based on the number of Pd···Pd distances, as derived from the EXAFS data, their size can be estimated to be approximately two unit cells, or ca. 1.0 nm(3). For platinum(II), EXAFS data of the polynuclear species formed in the slow hydrolysis process show Pt-O and Pt···Pt distances identical to those of amorphous platinum(II) oxide, precipitating from the solution studied. The Pt···Pt distances are somewhat different from those reported for crystalline platinum(II) oxide. The polynuclear platinum(II) complexes have a similar structure to the palladium ones, but they are somewhat larger, with an estimated diameter of 1.5-3.0 nm. It has not been possible to precipitate any of these species by ultracentrifugation. They are detectable by SAXS, indicating diameters between 0.7 and 2 nm, in excellent agreement with the EXAFS observations. The number of oxido- relative to hydroxido bridges will increase with increasing size of the complex. The charge of the complexes will remain about the same, +4, at growth, with approximate formulas [Pd10O4(OH)8(H2O)12](4+) and [Pt14O8(OH)8(H2O)12](4+) for complexes with a size of 2 and 3 unit cells of the corresponding solid metal oxide

  19. Fluids circulations during the formation of the Naxos Metamorphic Core Complex (Greece)

    NASA Astrophysics Data System (ADS)

    Vanderhaeghe, Olivier; Boiron, Marie-Christine; Siebenaller, Luc

    2015-04-01

    The island of Naxos, in the central part of the Cycladic Metamorphic Core Complex (Greece) represents a perfect example to address the evolution of fluid circulations during collapse of an orogenic belt. It displays a complex detachment system characterized by mylonites, cataclasites and high-angle normal faults which geometric relationships reflect rheological layering of the orogenic crust and its evolution during collapse. The chemistry of fluid inclusions determined by microthermometry, RAMAN spectroscopy, LA-ICPMS, and crush-leach combined with C and H isotopic signatures point to three distinct types of fluids, namely (i) a H2O-dominated fluid, (ii) a composite H2O-CO2 fluid, and (iii) a NaCl-rich fluid concentrated in metals. These different types of fluids are interpreted to reflect mixtures to various degrees among fluids generated by (i) condensation of clouds (meteoric aqueous fluid), (ii) dehydration and decarbonatation of metasedimentary rocks during metamorphism (metamorphic aqueous-carbonic fluid), and (iii) crystallization of granitic magmas (magmatic saline fluid with high metal contents). The distribution of fluids with respect to microstructures evidences the close link between deformation and fluid circulations at the mineral scale from intracristalline deformation to fracturing. The orientation of fluid inclusion planes, veins and alteration zones allows to identify the scale and geometry of the reservoir into which fluids are circulating and their evolution during the formation of the Metamorphic Core Complex. These data indicate that the orogenic crust is subdivided in two reservoirs separated by the ductile/fragile transition. Meteoric fluids circulate in the upper crust affected by brittle deformation whereas metamorphic and magmatic fluids circulate in relation to intracristalline ductile deformation affecting the lower crust. The geometry of these reservoirs evolves during the formation of the Naxos Metamorphic Core Complex as the

  20. Voltammetric analysis of Cu (II), Cd (II) and Zn (II) complexes and their cyclic voltammetry with several cephalosporin antibiotics.

    PubMed

    Abo El-Maali, N; Osman, A H; Aly, A A M; Al-Hazmi, G A A

    2005-02-01

    Both osteryoung square wave voltammetry and cyclic voltammetry have been utilized to elucidate and confirm the possible complexation reaction that occur between the various cephalosporin antibiotics and either the toxic, non-essential metal ion, viz. Cd (II), or the essential but toxic (when their concentration exceeds certain level in serum) metal ions, viz. Cu (II) and Zn (II). Voltammetric measurements indicated the existence of 1:1 metal-to-ligand ratio (as in cephalexin and cephapirin complexes), 1:2 ratio (such as in cefamandole, cefuroxime and cefotaxime complexes) and 2:1 ratio in case of ceftazidime complexes. Adsorption behavior was evidenced for Cu (II)-cefuroxime or ceftazidime complexes as well as for those for Zn (II)-cephalexin or cephapirin. This phenomenon could be used for the determination of either the antibiotic or the metal ion using adsorptive stripping voltammetry. Detection limits down to 7x10(-10) M have been easily achieved.

  1. Kansas Vocational Agriculture Education. Basic Core Curriculum Project, Horticulture II.

    ERIC Educational Resources Information Center

    Albracht, James, Ed.

    This second horticulture guide is one of a set of three designated as the basic core of instruction for horticulture programs in Kansas. Units of instruction are presented in eight sections: (1) Leadership, (2) Supervised Occupational Experience, (3) Plant Propagation, (4) Soil and Plant Growth Media, (5) Fertilizers, (6) Greenhouse, (7) Plant…

  2. Integrated structural model and membrane targeting mechanism of the human ESCRT-II complex

    PubMed Central

    Im, Young Jun; Hurley, James H.

    2008-01-01

    Summary ESCRT-II plays a pivotal role in receptor downregulation and multivesicular body biogenesis, and is conserved from yeast to humans. The crystal structures of two human ESCRT-II complex structures have been determined at 2.6 and 2.9 Å resolution, respectively. The complex has three lobes and contains one copy each of VPS22 and VPS36, and two copies of VPS25. The structure reveals a dynamic helical domain to which both the VPS22 and VPS36 subunits contribute, which connects the GLUE domain to the rest of the ESCRT-II core. Hydrodynamic analysis shows that intact ESCRT-II has a compact, closed conformation. ESCRT-II binds to the ESCRT-I VPS28 C-terminal domain subunit through a helix immediately C-terminal to the VPS36-GLUE domain. ESCRT-II is targeted to endosomal membranes by the lipid binding activities of both the Vps36 GLUE domain and the first helix of Vps22. These data provide a unifying structural and functional framework for the ESCRT-II complex. PMID:18539118

  3. Integrated structural model and membrane targeting mechanism of the human ESCRT-II complex

    SciTech Connect

    Im, Young Jun; Hurley, James H.

    2009-01-15

    ESCRT-II plays a pivotal role in receptor downregulation and multivesicular body biogenesis and is conserved from yeast to humans. The crystal structures of two human ESCRT-II complex structures have been determined at 2.6 and 2.9 {angstrom} resolution, respectively. The complex has three lobes and contains one copy each of VPS22 and VPS36 and two copies of VPS25. The structure reveals a dynamic helical domain to which both the VPS22 and VPS36 subunits contribute that connects the GLUE domain to the rest of the ESCRT-II core. Hydrodynamic analysis shows that intact ESCRT-II has a compact, closed conformation. ESCRT-II binds to the ESCRT-I VPS28 C-terminal domain subunit through a helix immediately C-terminal to the VPS36-GLUE domain. ESCRT-II is targeted to endosomal membranes by the lipid-binding activities of both the Vps36 GLUE domain and the first helix of Vps22. These data provide a unifying structural and functional framework for the ESCRT-II complex.

  4. Coherence in Dense Cores. II. The Transition to Coherence

    NASA Astrophysics Data System (ADS)

    Goodman, Alyssa A.; Barranco, Joseph A.; Wilner, David J.; Heyer, Mark H.

    1998-09-01

    After studying how line width depends on spatial scale in low-mass star-forming regions, we propose that ``dense cores'' (Myers & Benson 1983) represent an inner scale of a self-similar process that characterizes larger scale molecular clouds. In the process of coming to this conclusion, we define four distinct types of line width-size relation (Δv~Rai), which have power-law slopes a1, a2, a3, and a4, as follows: Type 1--multitracer, multicloud intercomparison; Type 2--single-tracer, multicloud intercomparison; Type 3--multitracer study of a single cloud; and Type 4--single-tracer study of a single cloud. Type 1 studies (of which Larson 1981 is the seminal example) are compendia of Type 3 studies which illustrate the range of variation in the line width-size relation from one region to another. Using new measurements of the OH and C18O emission emanating from the environs of several of the dense cores studied in NH3 by Barranco & Goodman (1998; Paper I), we show that line width increases with size outside the cores with a4 ~ 0.2. On scales larger than those traced by C18O or OH, 12CO and 13CO observations indicate that a4 increases to ~0.5 (Heyer & Schloerb 1997). By contrast, within the half-power contour of the NH3 emission from the cores, line width is virtually constant, with a4 ~ 0. We interpret the correlation between increasing density and decreasing Type 4 power-law slope as a ``transition to coherence.'' Our data indicate that the radius Rcoh at which the gas becomes coherent (i.e., a4 --> 0) is of order 0.1 pc in regions forming primarily low-mass stars. The value of the nonthermal line width at which ``coherence'' is established is always less than but still of order of the thermal line width of H2. Thus coherent cores are similar to, but not exactly the same as, isothermal balls of gas. Two other results bolster our proposal that a transition to coherence takes place at ~0.1 pc. First, the OH, C18O, and NH3 maps show that the dependence of column

  5. Ultrafast events in the electron photodetachment from the hexacyanoferrate(II) complex in solution

    NASA Astrophysics Data System (ADS)

    Pommeret, Stanislas; Naskrecki, Ryszard; van der Meulen, Peter; Ménard, Marjorie; Vigneron, Georges; Gustavsson, Thomas

    1998-05-01

    Following excitation of the hexacyanoferrate(II) complex in water with a 40 fs laser pulse at 267 nm, the absorption of the hydrated electron rises with a global time constant of 510 fs, whereas the characteristic absorption of the hexacyanoferrate(III) appears almost instantaneously. A transient absorption band around 490 nm is tentatively assigned to the charge-transfer-to-solvent (CTTS) state of the hexacyanoferrate(II). Its ultra-rapid decay (≪60 fs) is due to the electronic repulsion between the electron and its parent core.

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

    PubMed

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

    2010-01-01

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

  7. Detachment Shear Zone of the Atlantis Massif Oceanic Core Complex

    NASA Astrophysics Data System (ADS)

    Karson, J.; Fruh-Green, G.; Kelley, D.; Yoerger, D.; Jakuba, M.

    2005-12-01

    Near-bottom investigations of the cross section of the Atlantis Massif exposed in a major tectonic escarpment along the Atlantis Transform Fault provide an unprecedented view of the internal structure of the footwall domain of an oceanic core complex. Integrated direct observations, photogeology, and imaging define a mylonitic, low-angle detachment shear zone (DSZ) along the crest of the massif. The shear zone may project beneath the nearby, corrugated upper surface of the massif. The DSZ and related structures are inferred to be responsible for the unroofing of lower crustal gabbros and upper mantle peridotites by extreme, localized tectonic extension during seafloor spreading over the past 2 m.y. Strongly foliated serpentinites and talc-amphibole schists of the DSZ are about 100 m thick and can be traced continuously for at least 3 km in the spreading direction. Foliated DSZ rocks grade structurally downward into more massive basement rocks that lack a pervasive low-temperature deformation fabric. The main DSZ and underlying basement rocks are cut by discrete, anastomosing normal-slip, shear zones. Widely spaced, steeply dipping, normal faults cut all the older structures and localize serpentinization-driven hydrothermal outflow at the Lost City Hydrothermal Field. A thin (few meters) sequence of sedimentary breccias grading upward into pelagic limestones directly overlies the DSZ and may record a history of progressive rotation of the shear zone from an earlier moderately dipping attitude into its present, gently dipping orientation during lateral spreading and uplift.

  8. Clarifying the mechanism of cation exchange in Ca(II)[15-MC(Cu(II)ligand)-5] complexes.

    PubMed

    Lim, Choong-Sun; Tegoni, Matteo; Jakusch, Tamás; Kampf, Jeff W; Pecoraro, Vincent L

    2012-11-05

    The calcium metallacrown Ca(II)[15-MC(Cu(II)N(Trpha))-5](2+) was obtained by self-assembly of Ca(II), Cu(II), and tryptophanhydroxamic acid. Its X-ray structure shows that the core calcium ion is well-encapsulated in the five oxygen cavity of the metallacrown scaffold. The kinetics of Ca-Ln core metal substitution was studied by visible spectrophotometry by addition of Ln(III) nitrate to solutions of Ca(II)[15-MC(Cu(II)N(Trpha))-5](2+) in methanol solution at pH 6.2 (Ln(III) = La(III), Nd(III), Gd(III), Dy(III), Er(III)) to obtain the corresponding Ln(III)[15-MC(Cu(II)N(Trpha))-5](3+) complexes on the hours time scale. The reaction is first order in the two reactants (second order overall) with different rate constants across the lanthanide series. In particular, the rate for the Ca-Ln substitution decreases from La(III) to Gd(III) and then increases slightly from Gd(III) to Er(III). This substitution reaction occurs with second order rate constants ranging from 0.1543(3) M(-1) min(-1) for La(III) to 0.0720(6) M(-1) min(-1) for Gd(III). By means of the thermodynamic log K constants for the same reaction previously reported, the rate constants for the inverse Ln-Ca substitution were also determined. In this study, we demonstrated that the substitution reaction proceeds through a direct metal substitution and does not involve the disassembly of the MC scaffold. These observations in concert allow the proposition of a hypothesis that the dimension of the core metals play the major role in determining the rate constants of the substitution reaction. In particular, the largest lanthanides, which do not require complete encapsulation in the MC cavity, displace the Ca(II) ion faster, whereas in the back reaction Ca(II) displaces the smaller lanthanides faster as they interact relatively weakly with the metallacrown oxygen cavity.

  9. Removal of Ca2+ from the Oxygen-Evolving Complex in Photosystem II Has Minimal Effect on the Mn4O5 Core Structure: A Polarized Mn X-ray Absorption Spectroscopy Study

    SciTech Connect

    Lohmiller, Thomas; Shelby, Megan L.; Long, Xi; Yachandra, Vittal K.; Yano, Junko

    2015-05-19

    We studied Ca2+ -depleted and Ca2+ -reconstituted spinach photosystem II using polarized X-ray absorption spectroscopy of oriented PS II preparations to investigate the structural and functional role of the Ca2+ ion in the Mn4O5Ca cluster of the oxygen-evolving complex (OEC). Samples were prepared by low pH/citrate treatment as one-dimensionally ordered membrane layers and poised in the Ca2+ -depleted S1 (S1') and S2 (S2') states, the S2'YZ• state, at which point the catalytic cycle of water oxidation is inhibited, and the Ca2+ -reconstituted S1 state. Polarized Mn K-edge XANES and EXAFS spectra exhibit pronounced dichroism. Polarized EXAFS data of all states of Ca2+ -depleted PS II investigated show only minor changes in distances and orientations of the Mn-Mn vectors compared to the Ca2+ -containing OEC, which may be attributed to some loss of rigidity of the core structure. Thus, removal of the Ca2+ ion does not lead to fundamental distortion or rearrangement of the tetranuclear Mn cluster, which indicates that the Ca2+ ion in the OEC is not critical for structural maintenance of the cluster, at least in the S1 and S2 states, but fulfills a crucial catalytic function in the mechanism of the water oxidation reaction. On the basis of this structural information, reasons for the inhibitory effect of Ca2+ removal are discussed, attributing to the Ca2+ ion a fundamental role in organizing the surrounding (substrate) water framework and in proton-coupled electron transfer to YZ• (D1-Tyr161).

  10. Dimerization of core complexes as an efficient strategy for energy trapping in Rhodobacter sphaeroides.

    PubMed

    Chenchiliyan, Manoop; Timpmann, Kõu; Jalviste, Erko; Adams, Peter G; Hunter, C Neil; Freiberg, Arvi

    2016-06-01

    In the purple phototrophic bacterium Rhodobacter sphaeroides, light harvesting LH2 complexes transfer absorbed solar energy to RC-LH1-PufX core complexes, which are mainly found in the dimeric state. Many other purple phototrophs have monomeric core complexes and the basis for requiring dimeric cores is not fully established, so we analysed strains of Rba. sphaeroides that contain either native dimeric core complexes or altered monomeric cores harbouring a deletion of the first 12 residues from the N-terminus of PufX, which retains the PufX polypeptide but removes the major determinant of core complex dimerization. Membranes were purified from strains with dimeric or monomeric cores, and with either high or low levels of the LH2 complex. Samples were interrogated with absorption, steady-state fluorescence, and picosecond time-resolved fluorescence kinetic spectroscopies to reveal their light-harvesting and energy trapping properties. We find that under saturating excitation light intensity the photosynthetic membranes containing LH2 and monomeric core complexes have fluorescence lifetimes nearly twice that of membranes with LH2 plus dimeric core complexes. This trend of increased lifetime is maintained with RCs in the open state as well, and for two different levels of LH2 content. Thus, energy trapping is more efficient when photosynthetic membranes of Rba. sphaeroides consist of RC-LH1-PufX dimers and LH2 complexes.

  11. Hydride reactivity of Ni(II)-X-Ni(II) entities: mixed-valent hydrido complexes and reversible metal reduction.

    PubMed

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

    2013-01-28

    After the lithiation of PYR-H(2) (PYR(2-) =[{NC(Me)C(H)C(Me)NC(6)H(3)(iPr)(2)}(2)(C(5)H(3)N)](2-)), which is the precursor of an expanded β-diketiminato ligand system with two binding pockets, its reaction with [NiBr(2) (dme)] led to a dinuclear nickel(II)-bromide complex, [(PYR)Ni(μ-Br)NiBr] (1). The bridging bromide ligand could be selectively exchanged for a thiolate ligand to yield [(PYR)Ni(μ-SEt)NiBr] (3). In an attempt to introduce hydride ligands, both compounds were treated with KHBEt(3). This treatment afforded [(PYR)Ni(μ-H)Ni] (2), which is a mixed valent Ni(I)-μ-H-Ni(II) complex, and [(PYR-H)Ni(μ-SEt)Ni] (4), in which two tricoordinated Ni(I) moieties are strongly antiferromagnetically coupled. Compound 4 is the product of an initial salt metathesis, followed by an intramolecular redox process that separates the original hydride ligand into two electrons, which reduce the metal centres, and a proton, which is trapped by one of the binding pockets, thereby converting it into an olefin ligand on one of the Ni(I) centres. The addition of a mild acid to complex 4 leads to the elimination of H(2) and the formation of a Ni(II)Ni(II) compound, [(PYR)Ni(μ-SEt)NiOTf] (5), so that the original Ni(II) (μ-SEt)Ni(II) X core of compound 3 is restored. All of these compounds were fully characterized, including by X-ray diffraction, and their molecular structures, as well as their formation processes, are discussed.

  12. Evaluation of storing Shippingport Core II spent blanket fuel assemblies in the T Plant PWR Core II fuel pool without active cooling

    SciTech Connect

    Gilbert, E.R.; Lanning, D.D.; Dana, C.M.; Hedengren, D.C.

    1994-10-01

    PWR Core II fuel pool chiller-off test was conducted because it appeared possible that acceptable pool-water temperatures could be maintained without operating the chillers, thus saving hundreds of thousands of dollars in maintenance and replacement costs. Test results showed that the water-cooling capability is no longer needed to maintain pool temperature below 38{degrees}C (100{degrees}F).

  13. Equilibrium and Redox Kinetics of Copper(II)-Thiourea Complexes.

    PubMed

    Doona, Christopher J.; Stanbury, David M.

    1996-05-22

    Stopped-flow spectrophotometric measurements identify and determine equilibrium data for thiourea (tu) complexes of copper(II) formed in aqueous solution. In excess Cu(II), the complex ion [Cu(tu)](2+) has a stability constant beta(1) = 2.3 +/- 0.1 M(-)(1) and molar absorptivity at 340 nm of epsilon(1) = (4.0 +/- 0.2) x 10(3) M(-)(1) cm(-)(1) at 25.0 degrees C, 2.48 mM HClO(4), and &mgr; = 464 mM (NaClO(4)). The fast reduction of Cu(II) by excess tu obeys the rate law -d[Cu(II)]/dt = k'[Cu(II)](2)[tu](7) with a value for the ninth-order rate constant k' = (1.60 +/- 0.18) x 10(14) M(-)(8) s(-)(1), which derives from a rate-determining step involving the bimolecular decomposition of two complexed Cu(II) species. Copper(II) catalyzes the reduction of hexachloroiridate(IV) by tu according to the rate law -d[IrCl(6)(2)(-)]/dt = (k(2,unc)[tu](2) + k(1,cat) [tu](5)[Cu(II)])[IrCl(6)(2)(-)]. Least-squares analysis yields values of k(2,unc) and k(1,cat) equaling 385 +/- 4 M(-)(2) s(-)(1) and (3.7 +/- 0.1) x 10(13) M(-)(6) s(-)(1), respectively, at &mgr; = 115 mM (NaClO(4)). The corresponding mechanism has a rate-determining step that involves the oxidation of [Cu(II)(tu)(5)](2+) by [IrCl(6)](2)(-) rather than the bimolecular reaction of two cupric-tu complexes.

  14. I. Redox chemistry of bimetallic fulvalene complexes II. Oligocyclopentadienyl complexes

    SciTech Connect

    Brown, David Stephen

    1993-11-01

    The electrochemistry of the heterobimetallic complexes (fulvalene)WFe(CO)5 (30) and (fulvalene)WRu(CO)5 (31) has been investigated. Compound 30 is reduced in two one-electron processes, and this behavior was exploited synthetically to prepare a tetranuclear dimer by selective metal reduction. Complex 31 displayed a distinction between the metals upon reoxidation of the dianion, allowing the formation of a dimer by selective metal anion oxidation. The redox behavior of 30 led to an investigation of the use of electrocatalysis to effect metal-specific ligand substitution. It was found that reduction of 30 with a catalytic amount of CpFe(C6Me6) (97) in the presence of excess P(OMe)3 or PMe5 led to the formation of the zwitterions (fulvalene)[W(CO)3-][Fe(CO)PR3+] (107, R = P(OMe)3; 108, R = PMe3). Compound 31 also displayed unique behavior with different reducing agents, as the monosubstituted zwitterion (fulvalene)[W(CO)3-][Ru(CO)2(PMe3+] was obtained when 97 was used while the disubstituted complex (fulvalene) [W(CO)3-] [Ru(CO)(PMe3)2+] was produced when Cp*Fe(C6Me6) was the catalyst. Potential synthetic routes to quatercyclopentadienyl complexes were also explored. Various attempts to couple heterobimetallic fulvalene compounds proved to be unsuccessful. 138 refs.

  15. Synthesis and studies on Cu(II), Co(II), Ni(II) complexes of Knoevenagel β-diketone ligands.

    PubMed

    Sumathi, S; Tharmaraj, P; Sheela, C D; Anitha, C

    2012-11-01

    Transition metal complexes of various acetylacetone based ligands of the type ML [where M=Cu(II), Ni(II), Co(II); L=3-(aryl)-pentane-2,4-dione] have been synthesized. The structural features have been derived from their elemental analysis, magnetic susceptibility, molar conductance, IR, UV-Vis, (1)H NMR, Mass and ESR spectral studies. Conductivity measurements reveal that all the complexes are non-electrolytic in nature. Spectroscopic and other analytical data of the complexes suggest octahedral geometry for other metal(II) complexes. The redox behavior of the copper(II) complexes have been studied by cyclic voltammetry. The free ligands and their metal complexes have been screened for their in vitro biological activities against the bacteria Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus as well as the fungus Candida albicans by well diffusion method. The zone of inhibition value indicates that the most of the metal(II) complexes are found to possess increased activities compared to those of the free ligands. All synthesized compounds may serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG) efficiency of the ligands (L1-L3) was found to be considerable effect than that of urea and KDP (potassium dihydrogen phosphate).

  16. Synthesis and studies on Cu(II), Co(II), Ni(II) complexes of Knoevenagel β-diketone ligands

    NASA Astrophysics Data System (ADS)

    Sumathi, S.; Tharmaraj, P.; Sheela, C. D.; Anitha, C.

    2012-11-01

    Transition metal complexes of various acetylacetone based ligands of the type ML [where M = Cu(II), Ni(II), Co(II); L = 3-(aryl)-pentane-2,4-dione] have been synthesized. The structural features have been derived from their elemental analysis, magnetic susceptibility, molar conductance, IR, UV-Vis, 1H NMR, Mass and ESR spectral studies. Conductivity measurements reveal that all the complexes are non-electrolytic in nature. Spectroscopic and other analytical data of the complexes suggest octahedral geometry for other metal(II) complexes. The redox behavior of the copper(II) complexes have been studied by cyclic voltammetry. The free ligands and their metal complexes have been screened for their in vitro biological activities against the bacteria Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus as well as the fungus Candida albicans by well diffusion method. The zone of inhibition value indicates that the most of the metal(II) complexes are found to possess increased activities compared to those of the free ligands. All synthesized compounds may serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG) efficiency of the ligands (L1-L3) was found to be considerable effect than that of urea and KDP (potassium dihydrogen phosphate).

  17. Synthesis, structural characterization, thermal and electrochemical studies of Mn(II), Co(II), Ni(II) and Cu(II) complexes containing thiazolylazo ligands

    NASA Astrophysics Data System (ADS)

    Chavan, S. S.; Sawant, V. A.

    2010-02-01

    Some thiazolylazo derivatives and their metal complexes of the type [M(L)(H 2O)Cl]; M = Mn(II), Co(II), Ni(II), Cu(II) and L = 6-(2'-thiazolylazo)-2-mercapto-quinazolin-4-one (HL 1), 6-(4'-phenyl-2'-thiazolylazo)-2-mercapto-quinazolin-4-one (HL 2), 6-(2'-thiazolylazo)-2-mercapto-3-( m-tolyl)-quinazolin-4-one (HL 3) and 6-(4'-phenyl-2'-thiazolylazo)-2-mercapto-3-( m-tolyl)-quinazolin-4-one (HL 4) have been prepared. All the complexes were characterized on the basis of elemental analysis, molar conductance, magnetic moment, IR, UV-vis, ESR, TG-DTA and powder X-ray diffraction studies. IR spectra of these complexes reveal that the complex formation occurred through thiazole nitrogen, azo nitrogen, imino nitrogen and sulfur atom of the ligands. On the basis of electronic spectral data and magnetic susceptibility measurement octahedral geometry has been proposed for the Mn(II), Co(II) and Ni(II) complexes and distorted octahedral geometry for the Cu(II) complexes. Electrochemical behavior of Ni(II) complexes exhibit quasireversible oxidation corresponding to Ni(III)/Ni(II) couple along with ligand reduction. X-ray diffraction study is used to elucidate the crystal structure of the complexes.

  18. A substituted sulfonamide and its Co (II), Cu (II), and Zn (II) complexes as potential antifungal agents.

    PubMed

    Diaz, Jorge R A; Fernández Baldo, Martín; Echeverría, Gustavo; Baldoni, Héctor; Vullo, Daniela; Soria, Delia B; Supuran, Claudiu T; Camí, Gerardo E

    2016-01-01

    A sulfonamide 1-tosyl-1-H-benzo(d)imidazol-2-amine (TBZA) and three new complexes of Co(II), Cu(II), and Zn(II) have been synthesized. The compounds have been characterized by elemental analyses, FTIR, (1)H, and (13)C-NMR spectroscopy. The structure of the TBZA, and its Co(II) and Cu(II) complexes, was determined by X-ray diffraction methods. TBZA and its Co(II) complex crystallize in the triclinic P-1 space group, while the Cu(II) complex crystallizes in the monoclinic P21/c space group. Antifungal activity was screened against eight pathogenic yeasts: Candida albicans (DMic 972576), Candida krusei (DMic 951705), Candida glabrata (DMic 982882), Candida tropicalis (DMic 982884), Candida dubliniensis (DMic 93695), Candida guilliermondii (DMic 021150), Cryptococcus neoformans (ATCC 24067), and Cryptococcus gattii (ATCC MYA-4561). Results on the inhibition of various human (h) CAs, hCA I, II, IV, VII, IX, and XII, and pathogenic beta and gamma CAs are also reported.

  19. Activities for Challenging Gifted Learners by Increasing Complexity in the Common Core

    ERIC Educational Resources Information Center

    McKeone, Alyssa; Caruso, Lenora; Bettle, Kailyn; Chase, Ashley; Bryson, Bridget; Schneider, Jean S.; Rule, Audrey C.

    2015-01-01

    Gifted learners need opportunities for critical and creative thinking to stretch their minds and imaginations. Strategies for increasing complexity in the four core areas of language arts, mathematics, science, and social studies were addressed using the Common Core and Iowa Core Standards through several methods. Descriptive adjective object…

  20. Copper(II) complexes with heterocyclic hydroxyimino-containing ligands

    SciTech Connect

    Kogan, V.A.; Burlov, A.S.; Popov, L.D.; Lukov, V.V.; Koshchienko, Yu.V.; Tsupak, E.B.; Barchan, G.P.; Chigarenko, G.G.; Bolotnikov, V.S.

    1988-05-01

    The reaction of oximes (R = Ph (L'), C=N (L'')) with the copper(II) salts CuA/sub 2/ in methanol has given the complexes CuL/sub 2/ ' x H/sub 2/O and CuL/sub 2//sup ''/ x 2H/sub 2/O (I) (A = Acet/sup -/), CuHLCl/sub 2/ x H/sub 2/O (II) (A = Cl/sup -/), CuLOH(ClO/sub 4/)/sub 2/ x 2H/sub 2/O (III) (A = ClO/sub 4//sup -/) and the complexes Cu/sub 3/L/sub 3//sup '/OH(NO/sub 3/)/sub 2/ and Cu/sub 3/L/sub 3//sup ''/(OH)/sub 2/NO/sub 3/ (IV) (A = NO/sub 3//sup -/). Their physicochemical properties have been studied by the methods of IR spectroscopy and magnetochemistry. It has been shown that complexes I have a chelate structure and that their magnetic moments are not dependent on the temperature. An anti-ferromagnetic exchange interaction takes place in complexes II-IV. On the basis of magnetochemical measurements over a broad temperature range and data calculated in the framework of the Heisenberg-Dirac-Van Vleck model of isotropic exchange interactions, a dimeric structure has been proposed for the complexes of type II, and a trinuclear cluster structure has been proposed for complexes III and IV.

  1. Anticancer activity assessment of two novel binuclear platinum (II) complexes.

    PubMed

    Shahsavani, Mohammad Bagher; Ahmadi, Shamseddin; Aseman, Marzieh Dadkhah; Nabavizadeh, S Masoud; Rashidi, Mehdi; Asadi, Zahra; Erfani, Nasrollah; Ghasemi, Atiyeh; Saboury, Ali Akbar; Niazi, Ali; Bahaoddini, Aminollah; Yousefi, Reza

    2016-08-01

    In the current study, two binuclear Pt (II) complexes, containing cis, cis-[Me2Pt (μ-NN) (μ-dppm) PtMe2] (1), and cis,cis-[Me2Pt(μ-NN)(μ dppm) Pt((CH2)4)] (2) in which NN=phthalazine and dppm=bis (diphenylphosphino) methane were evaluated for their anticancer activities and DNA/purine nucleotide binding properties. These Pt (II) complexes, with the non-classical structures, demonstrated a significant anticancer activity against Jurkat and MCF-7 cancer cell lines. The results of ethidium bromide/acridine orange staining and Caspase-III activity suggest that these complexes were capable to stimulate an apoptotic mechanism of cell death in the cancer cells. Using different biophysical techniques and docking simulation analysis, we indicated that these complexes were also capable to interact efficiently with DNA via a non-intercalative mechanism. According to our results, substitution of cyclopentane (in complex 2) with two methyl groups (in complex 1) results in significant improvement of the complex ability to interact with DNA and subsequently to induce the anticancer activity. Overall, these binuclear Pt (II) complexes are promising group of the non-classical potential anticancer agents which can be considered as molecular templates in designing of highly efficient platinum anticancer drugs.

  2. Plant rhamnogalacturonan II complexation of heavy metal cations

    DOEpatents

    O`Neill, M.A.; Pellerin, P.J.M.; Warrenfeltz, D.; Vidal, S.; Darvill, A.G.; Albersheim, P.

    1999-03-02

    The present invention provides rhamnogalacturonan-II (RG-II) and relates to its ability to complex specific multivalent heavy metal cations. In the presence of boric acid, RG-II monomers form dimers that are cross-linked by a borate ester. The yield of such borate ester cross-linked dimers of RG-II is enhanced in the presence of specific heavy metal cations. The present invention further relates to the utility of RG-II in assays for the detection of specific heavy metal contamination; as a reagent useful in the removal of specific heavy metal cations contaminating foods and liquids, for example, fish, wines, etc.; as a pharmaceutical composition useful as an antidote in specific heavy metal cation poisoning; as a treatment for the detoxification of specific heavy metal cations from blood and/or tissues; and in a method of remediation of waters and soils contaminated with specific heavy metal cations. 15 figs.

  3. Plant rhamnogalacturonan II complexation of heavy metal cations

    DOEpatents

    O'Neill, Malcolm A.; Pellerin, Patrice J. M.; Warrenfeltz, Dennis; Vidal, Stephane; Darvill, Alan G.; Albersheim, Peter

    1999-01-01

    The present invention provides rhamnogalacturonan-II (RG-II) and relates to its ability to complex specific multivalent heavy metal cations. In the presence of boric acid, RG-II monomers form dimers that are cross-linked by a borate ester. The yield of such borate ester cross-linked dimers of RG-II is enhanced in the presence of specific heavy metal cations. The present invention further relates to the utility of RG-II in assays for the detection of specific heavy metal contamination; as a reagent useful in the removal of specific heavy metal cations contaminating foods and liquids, for example, fish, wines, etc.; as a pharmaceutical composition useful as an antidote in specific heavy metal cation poisoning; as a treatment for the detoxification of specific heavy metal cations from blood and/or tissues; and in a method of remediation of waters and soils contaminated with specific heavy metal cations.

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

    PubMed

    Chandra, Sulekh; Kumar, Anil

    2007-12-31

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

  5. Synthesis and characterization of Co(II), Ni(II) and Cu(II) complexes involving hydroxy antipyrine azodyes

    NASA Astrophysics Data System (ADS)

    Gaber, M.; Hassanein, A. M.; Lotfalla, A. A.

    2008-03-01

    The complexes formed between some hydroxy antipyrine azodyes and Co(II), Ni(II) and Cu(II) ions were studied spectrophotometrically in solution. The stoichiometry and stability constants of the metal chelates were determined. The spectrophotometric determination of the titled metal ions and titration using EDTA were reported. The chelating behaviour of the azodyes was confirmed by preparing the solid chelates in which their structures are elucidated using molar conductance, elemental, thermogravimetric (TGA) analyses, IR, ESR and electronic spectra as well as the magnetic measurements. Kinetic parameters are computed from the thermal decomposition data. The electrical properties for the metal complexes are measured from which the activation energies are calculated.

  6. Oxygen evolving complex in photosystem II: better than excellent.

    PubMed

    Najafpour, Mohammad Mahdi; Govindjee

    2011-09-28

    The Oxygen Evolving Complex in photosystem II, which is responsible for the oxidation of water to oxygen in plants, algae and cyanobacteria, contains a cluster of one calcium and four manganese atoms. This cluster serves as a model for the splitting of water by energy obtained from sunlight. The recent published data on the mechanism and the structure of photosystem II provide a detailed architecture of the oxygen-evolving complex and the surrounding amino acids. Biomimetically, we expect to learn some strategies from this natural system to synthesize an efficient catalyst for water oxidation, that is necessary for artificial photosynthesis.

  7. The Spatial Distribution of Complex Organic Molecules in the L1544 Pre-stellar Core.

    PubMed

    Jiménez-Serra, Izaskun; Vasyunin, Anton I; Caselli, Paola; Marcelino, Nuria; Billot, Nicolas; Viti, Serena; Testi, Leonardo; Vastel, Charlotte; Lefloch, Bertrand; Bachiller, Rafael

    2016-10-10

    The detection of complex organic molecules (COMs) toward cold sources such as pre-stellar cores (with T<10 K), has challenged our understanding of the formation processes of COMs in the interstellar medium. Recent modelling on COM chemistry at low temperatures has provided new insight into these processes predicting that COM formation depends strongly on parameters such as visual extinction and the level of CO freeze out. We report deep observations of COMs toward two positions in the L1544 pre-stellar core: the dense, highly-extinguished continuum peak with A V ≥30 mag within the inner 2700 au; and a low-density shell with average A V ~7.5-8 mag located at 4000 au from the core's center and bright in CH3OH. Our observations show that CH3O, CH3OCH3 and CH3CHO are more abundant (by factors ~2-10) toward the low-density shell than toward the continuum peak. Other COMs such as CH3OCHO, c-C3H2O, HCCCHO, CH2CHCN and HCCNC show slight enhancements (by factors ≤3) but the associated uncertainties are large. This suggests that COMs are actively formed and already present in the low-density shells of pre-stellar cores. The modelling of the chemistry of O-bearing COMs in L1544 indicates that these species are enhanced in this shell because i) CO starts freezing out onto dust grains driving an active surface chemistry; ii) the visual extinction is sufficiently high to prevent the UV photo-dissociation of COMs by the external interstellar radiation field; and iii) the density is still moderate to prevent severe depletion of COMs onto grains.

  8. Heat-induced reorganization of the structure of photosystem II membranes: role of oxygen evolving complex.

    PubMed

    Busheva, Mira; Tzonova, Iren; Stoitchkova, Katerina; Andreeva, Atanaska

    2012-12-05

    The sensitivity of the green plants' photosystem II (PSII) to high temperatures is investigated in PSII enriched membranes and in membranes, from which the oxygen evolving complex is removed. Using steady-state 77 K fluorescence and resonance Raman spectroscopy we analyze the interdependency between the temperature-driven changes in structure and energy distribution in the PSII supercomplex. The results show that the heat treatment induces different reduction of the 77 K fluorescence emission in both types of investigated membranes: (i) an additional considerable decrease of the overall fluorescence emission in Tris-washed membranes as compared to the native membranes; (ii) a transition point at 42°C(,) observed only in native membranes; (iii) a sharp reduction of the PSII core fluorescence in Tris-washed membranes at temperatures higher than 50°C; (iv) a 3 nm red-shift of F700 band's maximum in Tris-washed membranes already at 20°C and its further shift by 1 nm at temperature increase. Both treatments intensified their action by increasing the aggregation and dissociation of the peripheral light harvesting complexes. The oxygen-evolving complex, in addition to its main function to produce O(2), increases the thermal stability of PSII core by strengthening the connection between the core and the peripheral antenna proteins and by keeping their structural integrity.

  9. Preparation, characterization and biological activity of Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO 2(II) complexes of new cyclodiphosph(V)azane of sulfaguanidine

    NASA Astrophysics Data System (ADS)

    Sharaby, Carmen M.

    2005-11-01

    Novel hexachlorocyclodiphosph(V)azane of sulfaguanidine, H 4L, l,3-[ N'-amidino-sulfanilamide]-2,2,2,4,4,4-hexachlorocyclodiphosph(V)azane was prepared and its coordination behaviour towards the transition metal ions Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO 2(II) was studied. The structures of the isolated products are proposed based on elemental analyses, IR, UV-vis, 1H NMR, mass spectra, reflectance, magnetic susceptibility measurements and thermogravimetric analysis (TGA). The hyperfine interactions in the isolated complex compounds were studied using 14.4 keV γ-ray from radioactive 57Co (Mössbauer spectroscopy). The data show that the ligand are coordinated to the metal ions via the sulfonamide O and deprotonated NH atoms in an octahedral manner. The H 4L ligand forms complexes of the general formulae [(MX z) 2(H 2L)H 2O) n] and [(FeSO 4) 2 (H 4L) (H 2O) 4], where X = NO 3 in case of UO 2(II) and Cl in case of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II). The molar conductance data show that the complexes are non-electrolytes. The thermal behaviour of the complexes was studied and different thermodynamic parameters were calculated using Coats-Redfern method. Most of the prepared complexes showed high bactericidal activity and some of the complexes show more activity compared with the ligand and standards.

  10. Interfacial strain effect on type-I and type-II core/shell quantum dots

    NASA Astrophysics Data System (ADS)

    Gheshlaghi, Negar; Pisheh, Hadi Sedaghat; Karim, M. Rezaul; Malkoc, Derya; Ünlü, Hilmi

    2016-09-01

    A comparative experimental and theoretical study on the calculation of capped core diameter in ZnSe/ZnS, CdSe/Cd(Zn)S type-I and ZnSe/CdS type-II core/shell nanocrystals is presented. The lattice mismatch induced interface strain between core and shell was calculated from continuum elastic theory and applied in effective mass approximation method to obtain the corresponding capped core diameter. The calculated results were compared with diameter of bare cores (CdSe and ZnSe) from transmission electron microscopy images to obtain the amount of the stretched or squeezed core after deposition of tensile or compressive shells. The result of the study showed that the core is squeezed in ZnSe/ZnS and CdSe/Cd(Zn)S after compressive shell and stretched in ZnSe/CdS after tensile shell deposition. The stretched and squeezed amount of the capped core found to be in proportion with lattice mismatch amount in the core/shell structure.

  11. Design, syntheses, characterization, and cytotoxicity studies of novel heterobinuclear oxindolimine copper(II)-platinum(II) complexes.

    PubMed

    Aranda, Esther Escribano; Matias, Tiago Araújo; Araki, Koiti; Vieira, Adriana Pires; de Mattos, Elaine Andrade; Colepicolo, Pio; Luz, Carolina Portela; Marques, Fábio Luiz Navarro; da Costa Ferreira, Ana Maria

    2016-12-01

    Herein, the design and syntheses of two new mononuclear oxindolimine-copper(II) (1 and 2) and corresponding heterobinuclear oxindolimine Cu(II)Pt(II) complexes (3 and 4), are described. All the isolated complexes were characterized by spectroscopic techniques (UV/Vis, IR, EPR), in addition to elemental analysis and mass spectrometry. Cyclic voltammetry (CV) measurements showed that in all cases, one-electron quasi-reversible waves were observed, and ascribed to the formation of corresponding copper(I) complexes. Additionally, waves related to oxindolimine ligand reduction was verified, and confirmed using analogous oxindolimine-Zn(II) complexes. The Pt(IV/II) reduction, and corresponding oxidation, for complexes 3 and 4 occurred at very close values to those observed for cisplatin. By complementary fluorescence studies, it was shown that glutathione (GSH) cannot reduce any of these complexes, under the experimental conditions (room temperature, phosphate buffer 50mM, pH7.4), using an excess of 20-fold [GSH]. All these complexes showed characteristic EPR spectral profile, with parameters values gǁ>g⊥ suggesting an axially distorted environment around the copper(II) center. Interactions with calf thymus-DNA, monitored by circular dichroism (CD), indicated different effects modulated by the ligands. Finally, the cytotoxicity of each complex was tested toward different tumor cells, in comparison to cisplatin, and low values of IC50 in the range 0.6 to 4.0μM were obtained, after 24 or 48h incubation at 37°C. The obtained results indicate that such complexes can be promising alternative antitumor agents.

  12. Synthesis, DFT Calculation, and Antimicrobial Studies of Novel Zn(II), Co(II), Cu(II), and Mn(II) Heteroleptic Complexes Containing Benzoylacetone and Dithiocarbamate

    PubMed Central

    Ekennia, Anthony C.; Onwudiwe, Damian C.; Olasunkanmi, Lukman O.; Osowole, Aderoju A.; Ebenso, Eno E.

    2015-01-01

    Heteroleptic complexes of zinc(II), copper(II), manganese(II), and cobalt(II) of the types [MLL′(H2O)2]·nH2O and [MLL′]·nH2O have been synthesized using sodium N-methyl-N-phenyldithiocarbamate (L) and benzoylacetone (L′). The metal complexes were characterized by elemental analysis, electrical conductance, magnetic susceptibility, infrared (IR), and UV-visible spectroscopic studies. The electrical conductance measurements revealed the nonelectrolytic nature of the synthesized complexes. The results of the elemental analyses, magnetic susceptibility measurements, and electronic spectra inferred that the Zn(II) complex adopted a four-coordinate geometry while the Co(II), Cu(II), and Mn(II) complexes assumed octahedral geometries. The IR spectra showed that the metal ions coordinated with the ligands via the S- and O-donor atoms. The geometry, electronic, and thermodynamic parameters of the complexes were obtained from density functional theory (DFT) calculations. The spin density distributions, relative strength of H–bonds, and thermodynamic parameters revealed that the order of stability of the metal complexes is Mn < Co < Cu > Zn. The agar diffusion methods were used to study the antimicrobial activity of the complexes against two Gram positive bacteria (S. aureus and S. pneumoniae), one Gram negative bacterium (E. coli), and two fungi organisms (A. niger and A. candida) and the complexes showed a broad spectrum of activities against the microbes. PMID:26681931

  13. Copper(II) complexes with pyrazole derivatives - Synthesis, crystal structure, DFT calculations and cytotoxic activity

    NASA Astrophysics Data System (ADS)

    Kupcewicz, Bogumiła; Ciolkowski, Michal; Karwowski, Boleslaw T.; Rozalski, Marek; Krajewska, Urszula; Lorenz, Ingo-Peter; Mayer, Peter; Budzisz, Elzbieta

    2013-11-01

    The series of pyrazole derivatives (1a-4a) were used as bidentate N,N' ligands to obtain neutral Cu(II) complexes of ML2Cl2 type (1b-4b). The molecular structures of ligand 1a and Cu(II) complex 4b were determined by X-ray crystallography and theoretical DFT calculations. In this study, three functionals B3LYP, BP86 and mPW1PW91 with different basis sets and two effective core potentials Los Alamos and Stuttgart/Dresden were performed. The DFT study disclosed the usefulness of BP86 functional with SDD-ECP for Cu(II) ion and dedicated D95 basis set for other non-transition metal atoms, with the exclusion of Cl for which 6-31++G(2df,2pd) were used. The structural analysis shows that the presence of phenyl substituent in a pyrazole ring contributed to Cu-N bond elongation, which can result in different reactivity of complexes 1b and 3b. The cytotoxicity of the obtained compounds was evaluated on three cancer cells lines: HL-60, NALM-6 and WM-115. The complexes have exhibited similar moderate antiproliferative activity. All the complexes, except for 1b, were found to be more active against three cancer cell lines than uncomplexed pyrazoles. The lipophilicity and electrochemical properties of ligands and complexes was also studied. For complexes with ligand 1a and 3a only one reduction process at the metal centre occurs (Cu(II) → Cu(I)) with oxidization of Cu(I)-Cu(II) in the backward step.

  14. Reactions of Dinuclear Platinum(II) Complexes with Peptides.

    PubMed

    Rajković, Snežana; Živković, Marija D; Djuran, Miloš I

    2016-01-01

    The present review article highlights recent findings in the reactions between different dinuclear Pt(II) complexes with peptides containing cysteine, methionine and histidine residues. The reactions of {trans-[Pt(NH3)2Cl]2(μ-X)}(2+) and {trans-[Pt(NH3)2(H2O)]2(μ-X)}(4+) type complexes with different bridging ligands (X) (X = pyrazine, 4,4'-bipyridyl and 1,2-bis(4-pyridyl)ethane) with the tripeptide glutathione proceeded in two steps. In the first step, one water or chlorido ligand of the dinuclear Pt(II) complex was substituted by the sulfhydryl group of GSH, while in the second step, the remaining water or chlorido ligand from the dinuclear Pt(II)-peptide complex was replaced by the second molecule of glutathione, finally leading to the formation of the {trans-[Pt(NH3)2(GS)]2(μ-X)}(2+) complex. It was shown that the bridging ligand had an important influence on the reactivity of these complexes with glutathione. No hydrolytic cleavage of any amide bond was observed in the reactions between these complexes and glutathione. However, in reactions performed in acidic media (2.0 < pH < 2.5) between dinuclear Pt(II) complexes with the general formulae {[Pt(L)(H2O)]2(μ-diazine)}(4+) (L is different bidentate coordinated diamine ligands and diazine is a pyrazine- or pyridazine-bridging ligand) and Nacetylated peptides containing L-methionine and L-histidine amino acids in the side chains (Ac-L-Met-Gly, Ac-L-His-Gly and Ac-L-Met-Gly-L-His-GlyNH2), regioselective cleavage of these peptides occurred. The mechanism of these hydrolytic reactions was discussed in relation to the structure of the diazine-bridged Pt(II) complex and the investigated peptides. A systematic summary of these results could contribute to the future design of new dinuclear Pt(II) complexes as potential reagents for regioselective cleavage of peptides and proteins.

  15. Surface complexation of Pb(II) by hexagonal birnessite nanoparticles

    SciTech Connect

    Kwon, K.; Refson, K.; Sposito, G.

    2010-10-15

    Natural hexagonal birnessite is a poorly-crystalline layer type Mn(IV) oxide precipitated by bacteria and fungi which has a particularly high adsorption affinity for Pb(II). X-ray spectroscopic studies have shown that Pb(II) forms strong inner-sphere surface complexes mainly at two sites on hexagonal birnessite nanoparticles: triple corner-sharing (TCS) complexes on Mn(IV) vacancies in the interlayers and double edge-sharing (DES) complexes on lateral edge surfaces. Although the TCS surface complex has been well characterized by spectroscopy, some important questions remain about the structure and stability of the complexes occurring on the edge surfaces. First-principles simulation techniques such as density functional theory (DFT) offer a useful way to address these questions by providing complementary information that is difficult to obtain by spectroscopy. Following this computational approach, we used spin-polarized DFT to perform total-energy-minimization geometry optimizations of several possible Pb(II) surface complexes on model birnessite nanoparticles similar to those that have been studied experimentally. We first validated our DFT calculations by geometry optimizations of (1) the Pb-Mn oxyhydroxide mineral, quenselite (PbMnO{sub 2}OH), and (2) the TCS surface complex, finding good agreement with experimental structural data while uncovering new information about bonding and stability. Our geometry optimizations of several protonated variants of the DES surface complex led us to conclude that the observed edge-surface species is very likely to be this complex if the singly-coordinated terminal O that binds to Pb(II) is protonated. Our geometry optimizations also revealed that an unhydrated double corner-sharing (DCS) species that has been proposed as an alternative to the DES complex is intrinsically unstable on nanoparticle edge surfaces, but could become stabilized if the local coordination environment is well-hydrated. A significant similarity exists

  16. Surface complexation of Pb(II) by hexagonal birnessite nanoparticles

    NASA Astrophysics Data System (ADS)

    Kwon, Kideok D.; Refson, Keith; Sposito, Garrison

    2010-12-01

    Natural hexagonal birnessite is a poorly crystalline layer type Mn(IV) oxide precipitated by bacteria and fungi which has a particularly high adsorption affinity for Pb(II). X-ray spectroscopic studies have shown that Pb(II) forms strong inner-sphere surface complexes mainly at two sites on hexagonal birnessite nanoparticles: triple corner-sharing (TCS) complexes on Mn(IV) vacancies in the interlayers and double edge-sharing (DES) complexes on lateral edge surfaces. Although the TCS surface complex has been well characterized by spectroscopy, some important questions remain about the structure and stability of the complexes occurring on the edge surfaces. First-principles simulation techniques such as density functional theory (DFT) offer a useful way to address these questions by providing complementary information that is difficult to obtain by spectroscopy. Following this computational approach, we used spin-polarized DFT to perform total-energy-minimization geometry optimizations of several possible Pb(II) surface complexes on model birnessite nanoparticles similar to those that have been studied experimentally. We first validated our DFT calculations by geometry optimizations of (1) the Pb-Mn oxyhydroxide mineral, quenselite (PbMnO 2OH), and (2) the TCS surface complex, finding good agreement with experimental structural data while uncovering new information about bonding and stability. Our geometry optimizations of several protonated variants of the DES surface complex led us to conclude that the observed edge-surface species is very likely to be this complex if the singly coordinated terminal O that binds to Pb(II) is protonated. Our geometry optimizations also revealed that an unhydrated double corner-sharing (DCS) species that has been proposed as an alternative to the DES complex is intrinsically unstable on nanoparticle edge surfaces, but could become stabilized if the local coordination environment is well-hydrated. A significant similarity exists in

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

    PubMed

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

    2006-04-01

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

  18. Cobalt(II) complexes with hydroxypyridines and halogenides

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  19. Titanium dioxide mediated photocatalysis of Pb(II)- and Co(II)-EDTA complexes

    SciTech Connect

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

    1995-12-31

    The photocatalysis of lead and cobalt(II) complexed to EDTA was evaluated under a variety of experimental conditions. Adsorption characteristics of the metals and the metal complexes were also determined. A recirculating batch system was used to quantify photocatalytic oxidation rates. EDTA mineralization and total dissolved metal were monitored. Separations of Co(II*), Co(II)-EDTA, and Co(III)-EDTA were made with a method using Dowex cation exchange resin. Adsorptions of Pb(II), Co(II), EDTA, and the corresponding metal complexes was examined using concentrations of 10{sup -}{sup 5} to 10{sup -}{sup 3} M in 2 g/L TiO{sub 2}. After purging and pH adjustment, the samples were shaken overnight. The final pH and metal and TOC concentrations were determined. Results showed that the photocatablytic oxidation of metal-EDTA complexes is independent of pH from 5 to 7. This contrasts with the adsorption of these species onto TiO{sub 2}, which decreases at neutral-high pH, suggesting that adsorption is not a prerequisite to photocalysis. For Co(II)-EDTA, a competing pH dependent conversion to Co(III)-EDTA is noted.

  20. Physical Properties of Samples Cored From Atlantis Oceanic Core Complex, Mid-Atlantic Ridge 30 N

    NASA Astrophysics Data System (ADS)

    Searle, R.; Blackman, D.; Karner, G.; Harris, A.; Frost, R.

    2005-12-01

    IODP expedition 304/305 penetrated 1415 m into Atlantis Oceanic Core Complex, in 1.5 - 2.0 My crust, 12 km W of the Mid-Atlantic Ridge axis. Bulk magnetic susceptibility (MS), non-contact resistivity (NCR), P-wave velocity (Vp), bulk density, porosity and thermal properties were measured on recovered samples of peridotite, olivine-rich troctolite, olivine gabbro, gabbro, oxide gabbro, diabase and basalt. The most variable properties were MS and NCR, which were highly correlated, implying that the same minerals carry each signal, most likely Fe-Ti oxides such as magnetite and ilmenite and possibly minor sulfides. MS generally increased with iron content and decreased in intervals where magnetite had altered to ilmenite in diabase. High MS tends to concentrate in narrow bands and correlates with oxide- and sulfide-bearing gabbros and serpentinized zones (reflecting magnetite production during alteration). It exceeds 0.00001 SI in some oxide gabbros, equivalent to 8% magnetite by volume. MS is thus a valuable aid for mapping zones of oxide injection and serpentinization or other alteration and for stratigraphic correlation between holes. Core sample Vp is generally constant at about 5.5 km/s to 350 mbsf, increases to around 6.0 km/s at 450 mbsf and maintains this value to 750 mbsf, below which there is a steady decrease to about 5.8 km/s at 1200 mbsf, then a sharper decrease to 5.5 km/s at the bottom of the hole. The initial increase may be caused by closing cracks. The 10% decrease from 750 mbsf is a surprise: it may be real or perhaps due to overburden stress release. However, there is no corresponding reduction in bulk density with depth to indicate microscopic cracking during recovery. The final sharp decrease may reflect progressively increasing alteration. The largest local Vp variations are associated with massive olivine gabbros and troctolitic gabbros. A minimum between 300 and 350 mbsf reflects a zone of serpentinization. There is no significant seismic

  1. Cadmium(II) complex formation with cysteine and penicillamine.

    PubMed

    Jalilehvand, Farideh; Leung, Bonnie O; Mah, Vicky

    2009-07-06

    The complex formation between cadmium(II) and the ligands cysteine (H(2)Cys) and penicillamine (H(2)Pen = 3,3'-dimethylcysteine) in aqueous solutions, having C(Cd(II)) approximately 0.1 mol dm(-3) and C(H(2)L) = 0.2-2 mol dm(-3), was studied at pH = 7.5 and 11.0 by means of (113)Cd NMR and Cd K- and L(3)-edge X-ray absorption spectroscopy. For all cadmium(II)-cysteine molar ratios, the mean Cd-S and Cd-(N/O) bond distances were found in the ranges 2.52-2.54 and 2.27-2.35 A, respectively. The corresponding cadmium(II)-penicillamine complexes showed slightly shorter Cd-S bonds, 2.50-2.53 A, but with the Cd-(N/O) bond distances in a similar wide range, 2.28-2.33 A. For the molar ratio C(H(2)L)/C(Cd(II)) = 2, the (113)Cd chemical shifts, in the range 509-527 ppm at both pH values, indicated complexes with distorted tetrahedral CdS(2)N(N/O) coordination geometry. With a large excess of cysteine (molar ratios C(H(2)Cys)/C(Cd(II)) >or= 10), complexes with CdS(4) coordination geometry dominate, consistent with the (113)Cd NMR chemical shifts, delta approximately 680 ppm at pH 7.5 and 636-658 ppm at pH 11.0, and their mean Cd-S distances were 2.53 +/- 0.02 A. At pH 7.5, the complexes are almost exclusively sulfur-coordinated as [Cd(S-cysteinate)(4)](n-), while at higher pH, the deprotonation of the amine groups promotes chelate formation. At pH 11.0, a minor amount of the [Cd(Cys)(3)](4-) complex with CdS(3)N coordination is formed. For the corresponding penicillamine solutions with molar ratios C(H(2)Pen)/C(Cd(II)) >or= 10, the (113)Cd NMR chemical shifts, delta approximately 600 ppm at pH 7.5 and 578 ppm at pH 11.0, together with the average bond distances, Cd-S 2.53 +/- 0.02 A and Cd-(N/O) 2.30-2.33 A, indicate that [Cd(penicillaminate)(3)](n-) complexes with chelating CdS(3)(N/O) coordination dominate already at pH 7.5 and become mixed with CdS(2)N(N/O) complexes at pH 11.0. The present study reveals differences between cysteine and penicillamine as ligands to the

  2. Free flap transfer for complex regional pain syndrome type II

    PubMed Central

    Matsuda, Ken; Kikuchi, Mamoru; Murase, Tsuyoshi; Hosokawa, Ko; Shibata, Minoru

    2014-01-01

    Abstract A patient with complex regional pain syndrome type II was successfully treated using free anterolateral thigh flap transfer with digital nerve coaptation to the cutaneous nerve of the flap. Release of the scarred tissue and soft tissue coverage with targeted sensory nerve coaptation were useful in relieving severe pain. PMID:27252946

  3. Molecular Models of Ruthenium(II) Organometallic Complexes

    ERIC Educational Resources Information Center

    Coleman, William F.

    2007-01-01

    This article presents the featured molecules for the month of March, which appear in the paper by Ozerov, Fafard, and Hoffman, and which are related to the study of the reactions of a number of "piano stool" complexes of ruthenium(II). The synthesis of compound 2a offers students an alternative to the preparation of ferrocene if they are only…

  4. Hydrolytic cleavage of DNA by quercetin zinc(II) complex.

    PubMed

    Jun, Tan; Bochu, Wang; Liancai, Zhu

    2007-03-01

    Quercetin zinc(II) complex was investigated focusing on its hydrolytic activity toward DNA. The complex successfully promotes the cleavage of plasmid DNA, producing single and double DNA strand breaks. The amount of conversion of supercoiled form (SC) of plasmid to the nicked circular form (NC) depends on the concentration of the complex as well as the duration of incubation of the complex with DNA. The rate of conversion of SC to NC is 1.68x10(-4) s(-1) at pH 7.2 in the presence of 100 microM of the complex. The hydrolytic cleavage of DNA by the complex is supported by the evidence from free radical quenching, thiobarbituric acid-reactive substances (TBARS) assay, and T4 ligase ligation.

  5. Hydrolytic cleavage of DNA by quercetin manganese(II) complexes.

    PubMed

    Jun, Tan; Bochu, Wang; Liancai, Zhu

    2007-04-01

    Quercetin manganese(II) complexes were investigated focusing on its DNA hydrolytic activity. The complexes successfully promote the cleavage of plasmid DNA, producing single and double DNA strand breaks. The amount of conversion of supercoiled form (SC) of plasmid DNA to the nicked circular form (NC) depends on the concentration of the complex as well as the duration of incubation of the complexes with DNA. The maximum rate of conversion of the supercoiled form to the nicked circular form at pH 7.2 in the presence of 100 microM of the complexes is found to be 1.32 x 10(-4) s(-1). The hydrolytic cleavage of DNA by the complexes was supported by the evidence from free radical quenching, thiobarbituric acid-reactive substances (TBARS) assay and T4 ligase ligation.

  6. Spectroscopic and fluorescence studies on Mn(II), Co(II), Ni(II) and Cu(II) complexes with NO donor fluorescence dyes

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; El-Metwaly, Nashwa M.

    2011-10-01

    The reactions of the two common dyes [2TMPACT and 4PENI] with Mn(II), Co(II), Ni(II) and Cu(II) ions were done. All the isolated complexes have been characterized by physicochemical and spectroscopic techniques. The IR data reflect the bidentate mode of 2TMPACT towards the mononuclear complex [Mn(II)] even its tetradentate in binuclear complexes [Co(II) and Cu(II)]. However, the bidentate mode is the only behavior of 4PENI ligand towards each metal ion in its mononuclear complexes. The UV-vis spectral analysis beside the magnetic moment measurements are proposed different geometries concerning each metal ions with the two ligands under investigation, as the Mn(II)-2TMPACT complex is an octahedral but Mn(II)-4PENI is a tetrahedral geometry. All the synthesized compounds are thermogravimetrically investigated. The proposed thermal decomposition was discussed for each compound with each step as well as, the kinetic parameters were calculated for all preferrible decomposition steps. The mass spectroscopy tool was used to emphasis on the suitable molecular formula proposed and the fragmentation patterns were displayed. The fluorescence properties of the synthesized ligands and their complexes were studied in DMSO at room temperature.

  7. Spectroscopic and fluorescence studies on Mn(II), Co(II), Ni(II) and Cu(II) complexes with NO donor fluorescence dyes.

    PubMed

    Refat, Moamen S; el-Metwaly, Nashwa M

    2011-10-15

    The reactions of the two common dyes [2TMPACT and 4PENI] with Mn(II), Co(II), Ni(II) and Cu(II) ions were done. All the isolated complexes have been characterized by physicochemical and spectroscopic techniques. The IR data reflect the bidentate mode of 2TMPACT towards the mononuclear complex [Mn(II)] even its tetradentate in binuclear complexes [Co(II) and Cu(II)]. However, the bidentate mode is the only behavior of 4PENI ligand towards each metal ion in its mononuclear complexes. The UV-vis spectral analysis beside the magnetic moment measurements are proposed different geometries concerning each metal ions with the two ligands under investigation, as the Mn(II)-2TMPACT complex is an octahedral but Mn(II)-4PENI is a tetrahedral geometry. All the synthesized compounds are thermogravimetrically investigated. The proposed thermal decomposition was discussed for each compound with each step as well as, the kinetic parameters were calculated for all preferrible decomposition steps. The mass spectroscopy tool was used to emphasis on the suitable molecular formula proposed and the fragmentation patterns were displayed. The fluorescence properties of the synthesized ligands and their complexes were studied in DMSO at room temperature.

  8. 9-Triptycenecarboxylate-bridged diiron(II) complexes: Capture of the paddlewheel geometric isomer

    NASA Astrophysics Data System (ADS)

    Friedle, Simone; Kodanko, Jeremy J.; Fornace, Kyrstin L.; Lippard, Stephen J.

    2008-11-01

    The synthesis and characterization of diiron(II) complexes supported by 9-triptycenecarboxylate ligands ( -O 2CTrp) is described. The interlocking nature of the triptycenecarboxylates facilitates formation of quadruply bridged diiron(II) complexes of the type [Fe 2(μ-O 2CTrp) 4(L) 2] (L = THF, pyridine or imidazole) with a paddlewheel geometry. A systematic lengthening of the Fe-Fe distance occurs with the increase in steric bulk of the neutral donor L, resulting in values of up to 3 Å without disassembly of the paddlewheel structure. Reactions with an excess of water do not lead to decomposition of the diiron(II) core, indicating that these quadruply bridged complexes are of exceptional stability. The red-colored complexes [Fe 2(μ-O 2CTrp) 4(4-AcPy) 2] ( 10) and [Fe 2(μ-O 2CTrp) 4(4-CNPy) 2] ( 11) exhibit solvent-dependent thermochromism in coordinating solvents that was studied by variable temperature UV-vis spectroscopy. Reaction of [Fe 2(μ-O 2CTrp) 4(THF) 2] with N, N, N', N'-tetramethylethylenediamine (TMEDA), tetra- n-butyl ammonium thiocyanate, or excess 2-methylimidazole resulted in the formation of mononuclear complexes [Fe(O 2CTrp) 2(TMEDA)] ( 13), ( n-Bu 4N) 2[Fe(O 2CTrp) 2(SCN) 2] ( 14), and [Fe(O 2CTrp) 2(2-MeIm) 2] ( 15) having an O 4/N 2 coordination sphere composition.

  9. Energy transfer in photosystem I. Time resolved fluorescence of the native photosystem I complex and its core complex

    NASA Astrophysics Data System (ADS)

    Pålsson, Lars-Olof; Tjus, Staffan E.; Andersson, Bertil; Gillbro, Tomas

    1995-05-01

    Energy transfer within isolated spinach photosystem I (PS I) complexes with different antenna size were studied using time-resolved picosecond and steady-state fluorescence spectroscopy. In both the native PS I complexes and the PS I core complexes lacking the outer chlorophyll a/ b antenna we observed a fast dominating emission component ≈ 35 ps at room temperature which is associated with the trapping process by the reaction centre. In the native PS I complex there also appears a 120 ps component which was not observed in the PS I core complex. This component most likely represents an energy transfer from low energy pigments in the light-harvesting complex I antenna and into the core. Due to a very fast energy equilibration (< 10 ps) it was not possible to resolve the energy transfer at room temperature. At 77 K, however, it was possible to follow the energy transfer from F690 to F720 with a transfer time of ≈ 35 ps within the native PS I complex and slightly longer, 78 ps, in the PS I core complex. The native PS I complex also exhibited in the region 700-740 nm a 102 ps component which originates from F720 and represents energy transfer from F720 to P700 at 77 K. At low temperatures the PS I core complex exhibited a component of 161 ps which is associated with F720 and has the same function as the 102 ps component of the native PS I complex. We conclude that the F720 emission originates from pigments in the core antenna system. This emission also increases at low temperature. In the native PS I complex there is an initial increase in the F720 emission as the temperature is lowered but at 77 K the F735 emission originating from LHC I dominates.

  10. DNA Binding and Antitumor Activity of α-Diimineplatinum(II) and Palladium(II) Dithiocarbamate Complexes

    PubMed Central

    Mansouri-Torshizi, Hassan; Saeidifar, Maryam; Khosravi, Fatemeh; Divsalar, Adeleh; Saboury, Ali Akbar; Hassani, Fatemeh

    2011-01-01

    The two water-soluble designed platinum(II) complex, [Pt(Oct-dtc)(bpy)]NO3 (Oct-dtc = Octyldithiocarbamate and bpy = 2,2′ -bipyridine) and palladium(II) complex, [Pd(Oct-dtc)(bpy)]NO3, have been synthesized and characterized by elemental analyses, molar conductivity measurements, IR, 1H NMR, and electronic spectra studies. Studies of antitumor activity of these complexes against human cell tumor lines (K562) have been carried out. They show Ic50 values lower than that of cisplatin. The complexes have been investigated for their interaction with calf thymus DNA (CT-DNA) by utilizing the electronic absorption spectroscopy, fluorescence spectra, and ethidium bromide displacement and gel filtration techniques. Both of these water-soluble complexes bound cooperatively and intercalatively to the CT-DNA at very low concentrations. Several binding and thermodynamic parameters are also described. PMID:22110410

  11. Heterotrimetallic Ru(II)/Pd(II)/Ru(II) complexes: synthesis, crystalstructure, spectral characterization, DFT calculation and antimicrobial study.

    PubMed

    Al-Noaimi, Mousa; Nafady, Ayman; Warad, Ismail; Alshwafy, Rwaida; Husein, Ahmad; Talib, Wamidh H; Hadda, Taibi Ben

    2014-03-25

    New ruthenium(II) mononuclear complexes of the type [RuCl2(PPh3)2(η(2)-triamine)] (2) [RuCl(PPh3)2(η(3)-triamine)]Cl (5) (triemine=N(1)-(2-aminoethyl)-1,2-ethanediamine) have been synthesized by reacting [RuCl2(PPh3)3] (1) with one mole equivalent of N(1)-(2-aminoethyl)-1,2-ethanediamine in dichloromethane. Reaction of (2) with half-equivalent of (PhCN)2PdCl2 or Pd(OAc)2 in dichloromethane as a solvent afforded two novel heterotrimetallic Ru(II)-Pd(II)-Ru(II) complexes, [Ru(II)Cl2(PPh3)2(triamine)]2[Pd(II)X2](X=Cl, OAc) (3 and 4), bearing bioactive ligand. The progress of the undertaken reactions was monitored by (31)P{1H} NMR and FTIR. Crystal structure of complex 2 was confirmed by X-ray diffraction. The absorption spectrum of 2 in dichloromethane was modeled by time-dependent density functional theory (TD-DFT). The in vitro antimicrobial studies of complex 2-5 against an array of microorganisms (bacteria and fungi) were conducted. Complexes 3 and 4 exhibit high dual antibacterial and antifungal activity inhibiting microorganisms possibly via hydrolytic pathway which further evidenced by electrochemical analyses. The complexes 3 and 4 show a high inhibitory activity at 200 μg/ml concentration, suggesting that complexes 3 and 4 are two efficient catalytic inhibitor of microorganisms and further, they should be tested against cancer strains.

  12. The permeability of gabbro in oceanic core complexes

    NASA Astrophysics Data System (ADS)

    Titarenko, S.; McCaig, A. M.

    2013-12-01

    ridges in the Pacific, and volcanic plateaux in the Atlantic, suggest that the topmost basalts are extremely permeable even in crust up to 60 Ma, with estimates ranging from 10-13 to 10-9 m2. This has profound effects on the thermal structure of the crust, particularly where bare seamounts allow access of seawater to this shallow aquifer. In the Atlantic, up to 50% of the cuts has formed in the detachment mode of seafloor spreading, and lacks a continuous basaltic layer. The most prominent bare seamounts are often oceanic core complexes exposing gabbro and serpentinite. It follows that the hydrological and thermal regime in the Atlantic is likely to be inhomogeneous and unpredictable. Additionally, our data show that even in a tectonically active massif <1.2 M.y. in age, the large scale permeability of gabbro at low temperature is much less than that normally used in black smoker modelling (10-14 to 10-12 m2). Sheeted sill models of crustal construction at fast spreading ridges require removal of heat by deep circulation of seawater close to the ridge crest. Any permeability allowing such deep circulation is likely to be extremely transient in nature.

  13. Mechanism for generating the anomalous uplift of oceanic core complexes: Atlantis Bank, southwest Indian Ridge

    USGS Publications Warehouse

    Baines, A.G.; Cheadle, Michael J.; Dick, H.J.B.; Scheirer, A.H.; John, Barbara E.; Kusznir, N.J.; Matsumoto, T.

    2003-01-01

    Atlantis Bank is an anomalously uplifted oceanic core complex adjacent to the Atlantis II transform, on the southwest Indian Ridge, that rises >3 km above normal seafloor of the same age. Models of flexural uplift due to detachment faulting can account for ???1 km of this uplift. Postdetachment normal faults have been observed during submersible dives and on swath bathymetry. Two transform-parallel, large-offset (hundreds of meters) normal faults are identified on the eastern flank of Atlantis Bank, with numerous smaller faults (tens of meters) on the western flank. Flexural uplift associated with this transform-parallel normal faulting is consistent with gravity data and can account for the remaining anomalous uplift of Atlantis Bank. Extension normal to the Atlantis II transform may have occurred during a 12 m.y. period of transtension initiated by a 10?? change in spreading direction ca. 19.5 Ma. This extension may have produced the 120-km-long transverse ridge of which Atlantis Bank is a part, and is consistent with stress reorientation about a weak transform fault.

  14. The Spatial Distribution of Complex Organic Molecules in the L1544 Pre-stellar Core

    PubMed Central

    Jiménez-Serra, Izaskun; Vasyunin, Anton I.; Caselli, Paola; Marcelino, Nuria; Billot, Nicolas; Viti, Serena; Testi, Leonardo; Vastel, Charlotte; Lefloch, Bertrand; Bachiller, Rafael

    2016-01-01

    The detection of complex organic molecules (COMs) toward cold sources such as pre-stellar cores (with T<10 K), has challenged our understanding of the formation processes of COMs in the interstellar medium. Recent modelling on COM chemistry at low temperatures has provided new insight into these processes predicting that COM formation depends strongly on parameters such as visual extinction and the level of CO freeze out. We report deep observations of COMs toward two positions in the L1544 pre-stellar core: the dense, highly-extinguished continuum peak with AV ≥30 mag within the inner 2700 au; and a low-density shell with average AV ~7.5-8 mag located at 4000 au from the core’s center and bright in CH3OH. Our observations show that CH3O, CH3OCH3 and CH3CHO are more abundant (by factors ~2-10) toward the low-density shell than toward the continuum peak. Other COMs such as CH3OCHO, c-C3H2O, HCCCHO, CH2CHCN and HCCNC show slight enhancements (by factors ≤3) but the associated uncertainties are large. This suggests that COMs are actively formed and already present in the low-density shells of pre-stellar cores. The modelling of the chemistry of O-bearing COMs in L1544 indicates that these species are enhanced in this shell because i) CO starts freezing out onto dust grains driving an active surface chemistry; ii) the visual extinction is sufficiently high to prevent the UV photo-dissociation of COMs by the external interstellar radiation field; and iii) the density is still moderate to prevent severe depletion of COMs onto grains. PMID:27733899

  15. The Spatial Distribution of Complex Organic Molecules in the L1544 Pre-stellar Core

    NASA Astrophysics Data System (ADS)

    Jiménez-Serra, Izaskun; Vasyunin, Anton I.; Caselli, Paola; Marcelino, Nuria; Billot, Nicolas; Viti, Serena; Testi, Leonardo; Vastel, Charlotte; Lefloch, Bertrand; Bachiller, Rafael

    2016-10-01

    The detection of complex organic molecules (COMs) toward cold sources such as pre-stellar cores (with T < 10 K) has challenged our understanding of the formation processes of COMs in the interstellar medium. Recent modeling on COM chemistry at low temperatures has provided new insight into these processes predicting that COM formation depends strongly on parameters such as visual extinction and the level of CO freeze out. We report deep observations of COMs toward two positions in the L1544 pre-stellar core: the dense, highly extinguished continuum peak with A V ≥ 30 mag within the inner 2700 au; and a low-density shell with average A V ˜ 7.5-8 mag located at 4000 au from the core’s center and bright in CH3OH. Our observations show that CH3O, CH3OCH3, and CH3CHO are more abundant (by factors of ˜2-10) toward the low-density shell than toward the continuum peak. Other COMs such as CH3OCHO, c-C3H2O, HCCCHO, CH2CHCN, and HCCNC show slight enhancements (by factors ≤3), but the associated uncertainties are large. This suggests that COMs are actively formed and already present in the low-density shells of pre-stellar cores. The modeling of the chemistry of O-bearing COMs in L1544 indicates that these species are enhanced in this shell because (i) CO starts freezing out onto dust grains driving an active surface chemistry; (ii) the visual extinction is sufficiently high to prevent the UV photo-dissociation of COMs by the external interstellar radiation field; and (iii) the density is still moderate to prevent severe depletion of COMs onto grains.

  16. Class II 6.7 GHz Methanol Maser Association with Young Massive Cores Revealed by ALMA

    NASA Astrophysics Data System (ADS)

    Chibueze, James O.; Csengeri, Timea; Tatematsu, Ken’ichi; Hasegawa, Tetsuo; Iguchi, Satoru; Alhassan, Jibrin A.; Higuchi, Aya E.; Bontemps, Sylvain; Menten, Karl M.

    2017-02-01

    We explored the implication of the association (or lack of it) of 6.7 GHz class II methanol (CH3OH) masers with massive dense cores (MDCs) detected (within a sample of ATLASGAL selected infrared quiet massive clumps) at 0.9 mm with Atacama Large Millimeter/submillimeter array. We found 42 out of the 112 cores (37.5%) detected with the Atacama Compact Array (ACA) to be associated with 6.7 GHz CH3OH masers. The lowest mass core with CH3OH maser association is ∼ 12 {M}ȯ . The angular offsets of the ACA cores from the 6.7 GHz CH3OH maser peak positions range from 0.″17 to 4.″79, with a median value of 2.″19. We found a weak correlation between the 0.9 mm continuum (MDCs) peak fluxes and the peak fluxes of their associated methanol multibeam (MMB) 6.7 GHz CH3OH masers. About 90% of the cores associated with 6.7 GHz CH3OH masers have masses of >40 M ⊙. The CH3OH maser containing cores are candidates for embedded high-mass protostellar objects in their earliest evolutionary stages. With our ACA 0.9 continuum data compared with the MMB 6.7 GHz CH3OH maser survey, we have constrained the cores already housing massive protostars based on their association with the radiatively pumped 6.7 GHz CH3OH masers.

  17. Mixed metal hydroxycarboxylic acid complexes. Spectrophotometric study of complexes of U(VI) with In(III), Cu(II), Zn(II) and Cd(II)

    SciTech Connect

    Manzurola, E.; Apelblat, A.; Markovits, G.; Levy, O. )

    1988-01-01

    The formation of mixed metal complexes between uranium (VI), as the central metal ion, and aluminum (III), indium (III), copper (II), zinc (II) and cadmium (II), as the additional metal ions, with a hydroxycarboxylic acid chosen between citric, tartaric or malic, has been studied using spectrophotometric methods. The effect of pH has been examined, and the results show that at pH = 4 stable complexes are formed for most of the systems. At this pH the method of mole ratio and Job's method of continuous variations, were employed to determine the stoichiometry of the mixed metal complexes. Al(III), In(III) and Cu(II) showed a high tendency to form mixed metal complexes with U(VI), while the formation of complexes is uncertain for Cd(II) and Zn(II). The ratio of the ligand to the total metal ion has been found to be 2:1 and metal:metal ratios of 1:1 and 1:2 have been observed.

  18. Electrocatalytic water oxidation with a copper(II) polypeptide complex.

    PubMed

    Zhang, Ming-Tian; Chen, Zuofeng; Kang, Peng; Meyer, Thomas J

    2013-02-13

    A self-assembly-formed triglycylglycine macrocyclic ligand (TGG(4-)) complex of Cu(II), [(TGG(4-))Cu(II)-OH(2)](2-), efficiently catalyzes water oxidation in a phosphate buffer at pH 11 at room temperature by a well-defined mechanism. In the mechanism, initial oxidation to Cu(III) is followed by further oxidation to a formal "Cu(IV)" with formation of a peroxide intermediate, which undergoes further oxidation to release oxygen and close the catalytic cycle. The catalyst exhibits high stability and activity toward water oxidation under these conditions with a high turnover frequency of 33 s(-1).

  19. Novel cofactors and TFIIA mediate functional core promoter selectivity by the human TAFII150-containing TFIID complex.

    PubMed

    Martinez, E; Ge, H; Tao, Y; Yuan, C X; Palhan, V; Roeder, R G

    1998-11-01

    TATA-binding protein-associated factors (TAFIIs) within TFIID control differential gene transcription through interactions with both activators and core promoter elements. In particular, TAFII150 contributes to initiator-dependent transcription through an unknown mechanism. Here, we address whether TAFIIs within TFIID are sufficient, in conjunction with highly purified general transcription factors (GTFs), for differential core promoter-dependent transcription by RNA polymerase II and whether additional cofactors are required. We identify the human homologue of Drosophila TAFII150 through cognate cDNA cloning and show that it is a tightly associated component of human TFIID. More importantly, we demonstrate that the human TAFII150-containing TFIID complex is not sufficient, in the context of all purified GTFs and RNA polymerase II, to mediate transcription synergism between TATA and initiator elements and initiator-directed transcription from a TAFII-dependent TATA-less promoter. Therefore, TAFII-promoter interactions are not sufficient for the productive core promoter-selective functions of TFIID. Consistent with this finding, we have partially purified novel cofactor activities (TICs) that potentiate the TAFII-mediated synergism between TATA and initiator elements (TIC-1) and TAFII-dependent transcription from TATA-less promoters (TIC-2 and -3). Furthermore, we demonstrate an essential function for TFIIA in TIC- and TAFII-dependent basal transcription from a TATA-less promoter. Our results reveal a parallel between the basal transcription activity of TAFIIs through core promoter elements and TAFII-dependent activator function.

  20. Synthesis, spectroscopic, antimicrobial and DNA cleavage studies of new Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes with naphthofuran-2-carbohydrazide Schiff base

    NASA Astrophysics Data System (ADS)

    Halli, Madappa B.; Sumathi, R. B.

    2012-08-01

    A series of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes have been synthesized with newly synthesized Schiff base derived from naphthofuran-2-carbohydrazide and cinnamaldehyde. The elemental analyses of the complexes are confined to the stoichiometry of the type MLCl2 [M = Co(II) and Cu(II)], ML2Cl2 [M = Ni(II), Cd(II), Zn(II) and Hg(II)] respectively, where L is Schiff base ligand. Structures have been proposed from elemental analyses, IR, electronic, mass, 1H NMR, ESR spectral data, magnetic, and thermal studies. The measured low molar conductance values in DMF indicate that the complexes are non-electrolytes. Spectroscopic studies suggest coordination occurs through azomethine nitrogen and carbonyl oxygen of the ligand with the metal ions. The Schiff base and its complexes have been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal (Aspergillus niger, Aspergillus flavus, Cladosporium and Candida albicans) activities by minimum inhibitory concentration (MIC) method. The DNA cleavage studies by agarose gel electrophoresis method was studied for all the complexes.

  1. Comparison of Magnesium II Core-to-Wing Ratio Measurements During Solar Minimum 23/24

    NASA Astrophysics Data System (ADS)

    Machol, J. L.; Snow, M. A.; Viereck, R. A.; Weber, M.; Richard, E. C.; Puga, L. C.

    2013-12-01

    Solar extreme ultraviolet (EUV) radiation is the primary energy source to the Earth's upper atmosphere; it heats the thermosphere, creates the ionosphere, and drives photochemistry. A useful proxy for EUV irradiance is the Magnesium II Core-to-Wing Ratio (Mg II index) which is calculated from solar irradiance measurements near 280 nm. This poster compares different satellite measurements of the Mg II index made during the recent solar minimum. We also contrast the indices calculated from high spectral resolution data with indices derived with the classic calculation and 1.1 nm resolution data. These results will be combined with prior Mg II composite time series to create a composite that best represents solar activity over the spacecraft era - 35 years and counting.

  2. Synthesis, spectral characterization and biological evaluation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with thiosemicarbazone ending by pyrazole and pyridyl rings

    NASA Astrophysics Data System (ADS)

    Yousef, T. A.; Abu El-Reash, G. M.; Al-Jahdali, M.; El-Rakhawy, El-Bastawesy R.

    2014-08-01

    Here we present the synthesis of the new Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with chelating ligand (Z)-(2-((1,3-diphenyl-1H-pyrazol-4-yl)methylene) hydrazinyl)(pyridin-2-ylamino)methanethiol. All the complexes were characterized by elemental analysis, IR, 1H NMR, UV-vis, magnetic susceptibility measurements and EPR spectral studies. IR spectra of complexes showed that the ligand behaves as NN neutral bidentate, NSN mononegative tridentate and NSNN mononegative tetradentate. The electronic spectra and the magnetic measurements suggested the octahedral geometry for all complexes as well as the EPR confirmed the tetragonal distorted octahedral for Cu(II) complex. Cd(II) complex showed the highest inhibitory antioxidant activity either using ABTS method. The SOD-like activity exhibited those Cd(II) and Zn(II) complexes have strong antioxidative properties. We tested the synthesized compounds for antitumor activity and showed that the ability to kill liver (HePG2) and breast (MCF-7) cancer cells definitely.

  3. Mixed metal copper(II)-nickel(II) and copper(II)-zinc(II) complexes of multihistidine peptide fragments of human prion protein.

    PubMed

    Jószai, Viktória; Turi, Ildikó; Kállay, Csilla; Pappalardo, Giuseppe; Di Natale, Giuseppe; Rizzarelli, Enrico; Sóvágó, Imre

    2012-07-01

    Mixed metal copper(II)-nickel(II) and copper(II)-zinc(II) complexes of four peptide fragments of human prion protein have been studied by potentiometric, UV-vis and circular dichroism spectroscopic techniques. One peptide contained three histidyl residues: HuPrP(84-114) with H85 inside and H96, H111 outside the octarepeat domain. The other three peptides contained two histidyl residues; H96 and H111 for HuPrP(91-115) and HuPrP(84-114)H85A while HuPrP(84-114)H96A contained the histidyl residues at positions 85 and 111. It was found that both histidines of the latter peptides can simultaneously bind copper(II) and nickel(II) ions and dinuclear mixed metal complexes can exist in slightly alkaline solution. One molecule of the peptide with three histidyl residues can bind two copper(II) and one nickel(II) ions. H85 and H111 were identified as the major copper(II) and H96 as the preferred nickel(II) binding sites in mixed metal species. The studies on the zinc(II)-PrP peptide binary systems revealed that zinc(II) ions can coordinate to the 31-mer PrP peptide fragments in the form of macrochelates with two or three coordinated imidazol-nitrogens but the low stability of these complexes cannot prevent the hydrolysis of the metal ion in slightly alkaline solution. These data provide further support for the outstanding affinity of copper(II) ions towards the peptide fragments of prion protein but the binding of nickel(II) can significantly modify the distribution of copper(II) among the available metal binding sites.

  4. Copper(II) complexes of rat amylin fragments.

    PubMed

    Kállay, Csilla; Dávid, Agnes; Timári, Sarolta; Nagy, Eszter Márta; Sanna, Daniele; Garribba, Eugenio; Micera, Giovanni; De Bona, Paolo; Pappalardo, Giuseppe; Rizzarelli, Enrico; Sóvágó, Imre

    2011-10-14

    The fragments of rat amylin rIAPP(17-29) (Ac-VRSSNNLGPVLPP-NH(2)), rIAPP(17-22) (Ac-VRSSNN-NH(2)), rIAPP(19-22) (Ac-SSNN-NH(2)) and rIAPP(17-20) (Ac-VRSS-NH(2)) together with the related mutant peptides (Ac-VASS-NH(2) and Ac-VRAA-NH(2)) have been synthesized and their copper(II) complexes studied by potentiometric, UV-Vis, CD and EPR spectroscopic methods. Despite the lack of any common strongly coordinating donor functions some of these fragments are able to bind copper(II) ions in the physiological pH range. The longest fragment rat amylin(17-29) keeps one equivalent copper(II) ion in solution in the whole pH range, while two other peptides Ac-VRSSNN-NH(2) and Ac-SSNN-NH(2) are also able to interact with copper(II) ions in the slightly alkaline pH range. According to the spectral parameters of the complexes, the peptides can be classified into two different categories: (i) the tetrapeptides Ac-VRSS-NH(2), Ac-VASS-NH(2) and Ac-VRAA-NH(2) can interact with copper(II) only under strongly alkaline conditions (pH > 10.0) and the formation of only one species with four amide nitrogen coordination can be detected; (ii) the peptides Ac-VRSSNNLGPVLPP-NH(2), Ac-VRSSNN-NH(2) and Ac-SSNN-NH(2) can form complexes above pH 6.0 with the major stoichiometries [CuH(-2)L], [CuH(-3)L](-) and [CuH(-4)L](2-). These data support that rIAPP(17-29) can interact with copper(II) ions under physiological conditions and the SSNN tetrapeptide fragment can be considered as the shortest sequence responsible for metal binding. Density functional theory (DFT) calculations provide some information on the possible coordination modes of Ac-SSNN-NH(2) towards the copper(II) ion and suggest that for [CuH(-2)L], [CuH(-3)L](-) and [CuH(-4)L](2-), the binding of two, three and four deprotonated amide nitrogens, with NH(-) of the side chain of asparagine as anchoring group, is probable. Moreover, these data reveal that peptides can be effective metal binding ligands even in the absence of anchoring

  5. Has First-Grade Core Reading Program Text Complexity Changed across Six Decades?

    ERIC Educational Resources Information Center

    Fitzgerald, Jill; Elmore, Jeff; Relyea, Jackie Eunjung; Hiebert, Elfrieda H.; Stenner, A. Jackson

    2016-01-01

    The purpose of the study was to address possible text complexity shifts across the past six decades for a continually best-selling first-grade core reading program. The anthologies of one publisher's seven first-grade core reading programs were examined using computer-based analytics, dating from 1962 to 2013. Variables were Overall Text…

  6. The core collapse supernova rate from the SDSS-II supernova survey

    SciTech Connect

    Taylor, Matt; Cinabro, David; Dilday, Ben; Galbany, Lluis; Gupta, Ravi R.; Kessler, R.; Marriner, John; Nichol, Robert C.; Richmond, Michael; Schneider, Donald P.; Sollerman, Jesper

    2014-09-10

    We use the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SNS) data to measure the volumetric core collapse supernova (CCSN) rate in the redshift range (0.03 < z < 0.09). Using a sample of 89 CCSN, we find a volume-averaged rate of 1.06 ± 0.19 × 10{sup –4}((h/0.7){sup 3}/(yr Mpc{sup 3})) at a mean redshift of 0.072 ± 0.009. We measure the CCSN luminosity function from the data and consider the implications on the star formation history.

  7. The Core Collapse Supernova Rate from the SDSS-II Supernova Survey

    SciTech Connect

    Taylor, Matt; Cinabro, David; Dilday, Ben; Galbany, Lluis; Gupta, Ravi R.; Kessler, R.; Marriner, John; Nichol, Robert C.; Richmond, Michael; Schneider, Donald P.; Sollerman, Jesper

    2014-08-26

    We use the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SNS) data to measure the volumetric core collapse supernova (CCSN) rate in the redshift range (0.03 < z < 0.09). Using a sample of 89 CCSN, we find a volume-averaged rate of 1.06 ± 0.19 × 10(–)(4)((h/0.7)(3)/(yr Mpc(3))) at a mean redshift of 0.072 ± 0.009. We measure the CCSN luminosity function from the data and consider the implications on the star formation history.

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

    SciTech Connect

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

    2015-03-15

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

  9. Evidence for Footwall Rotation in an Oceanic Core Complex From IODP Core Samples Reoriented Using Borehole Wall Imagery

    NASA Astrophysics Data System (ADS)

    Morris, A.; Gee, J. S.; Pressling, N.; John, B. E.; MacLeod, C. J.; Grimes, C. B.; Searle, R. C.

    2008-12-01

    Oceanic core complexes expose lower crustal and upper mantle rocks on the seafloor by tectonic unroofing in the footwalls of large-slip detachment faults. The common occurrence of these structures in slow and ultra- slow spreading oceanic crust suggests they accommodate a significant component of plate divergence. However, the sub-surface geometry of oceanic detachment faults remains unclear. Competing models involve either: (a) displacement on planar, low-angle faults with little tectonic rotation; or (b) progressive shallowing by rotation of initially steeply dipping faults as a result of flexural unloading (the "rolling-hinge" model). We resolve this debate using paleomagnetic remanences as a marker for tectonic rotation within a unique 1.4 km long footwall section of gabbroic rocks recovered by Integrated Ocean Drilling Program (IODP) sampling at Atlantis Massif oceanic core complex on the Mid Atlantic Ridge (MAR). For the first time we have independently reoriented initially azimuthally-unconstrained drill-core samples of lower crustal gabbros to a true geographic reference frame by correlating structures in individual core pieces with those identified from oriented imagery of the borehole wall. This allows reorientation of paleomagnetic data and subsequent tectonic interpretation without the need for a priori assumptions on the azimuth of the rotation axis. Results indicate a 34°±7° counterclockwise rotation of the footwall around a MAR-parallel horizontal axis trending 007°±9°. This provides unequivocal confirmation of the key prediction of flexural, rolling-hinge models for oceanic core complexes, whereby faults initiate at higher dips and rotate to their present day low angle geometries.

  10. Recognition of core and flanking amino acids of MHC class II-bound peptides by the T cell receptor.

    PubMed

    Sant'Angelo, Derek B; Robinson, Eve; Janeway, Charles A; Denzin, Lisa K

    2002-09-01

    CD4 T cells recognize peptides bound to major histocompatibility complex (MHC) class II molecules. Most MHC class II molecules have four binding pockets occupied by amino acids 1, 4, 6, and 9 of the minimal peptide epitope, while the residues at positions 2, 3, 5, 7, and 8 are available to interact with the T cell receptor (TCR). In addition MHC class II bound peptides have flanking residues situated outside of this peptide core. Here we demonstrate that the flanking residues of the conalbumin peptide bound to I-A(k) have no effect on recognition by the D10 TCR. To study the role of peptide flanks for recognition by a second TCR, we determined the MHC and TCR contacting amino acids of the I-A(b) bound Ealpha peptide. The Ealpha peptide is shown to bind I-A(b) using four alanines as anchor residues. TCR recognition of Ealpha peptides with altered flanking residues again suggested that, in general, no specific interactions occurred with the peptide flanks. However, using an HLA-DM-mediated technique to measure peptide binding to MHC class II molecules, we found that the peptide flanking residues contribute substantially to MHC binding.

  11. DNase II digestion of the nucleosome core: precise locations and relative exposures of sites.

    PubMed

    Lutter, L C

    1981-09-11

    The precise locations and relative exposures of the DNase II-accessible sites in the nucleosome core DNA are determined using techniques previously employed for the enzyme DNase I. It is found that there are a number of similarities between the site exposure patterns for the two enzymes but that in general the DNase II seems to discriminate less among adjacent sites' accessibilities than does DNase I. The two enzymes attack essentially the same positions in the DNA, the average difference between the precise location of the site being less than one-half base for the two enzymes. Such close similarities in the digestion patterns of two enzymes with such different mechanisms of scission show that the patterns reflect the structure of the nucleosome core and not merely the properties of the particular enzyme used.

  12. Heterotrimetallic Ru(II)/Pd(II)/Ru(II) complexes: Synthesis, crystalstructure, spectral characterization, DFT calculation and antimicrobial study

    NASA Astrophysics Data System (ADS)

    Al-Noaimi, Mousa; Nafady, Ayman; Warad, Ismail; Alshwafy, Rwaida; Husein, Ahmad; Talib, Wamidh H.; Hadda, Taibi Ben

    2014-03-01

    New ruthenium(II) mononuclear complexes of the type [RuCl2(PPh3)2(η2-triamine)] (2) [RuCl(PPh3)2(η3-triamine)]Cl (5) (triemine = N1-(2-aminoethyl)-1,2-ethanediamine) have been synthesized by reacting [RuCl2(PPh3)3] (1) with one mole equivalent of N1-(2-aminoethyl)-1,2-ethanediamine in dichloromethane. Reaction of (2) with half-equivalent of (PhCN)2PdCl2 or Pd(OAc)2 in dichloromethane as a solvent afforded two novel heterotrimetallic Ru(II)-Pd(II)-Ru(II) complexes, [RuIICl2(PPh3)2(triamine)]2[PdIIX2](X = Cl, OAc) (3 and 4), bearing bioactive ligand. The progress of the undertaken reactions was monitored by 31P{1H} NMR and FTIR. Crystal structure of complex 2 was confirmed by X-ray diffraction. The absorption spectrum of 2 in dichloromethane was modeled by time-dependent density functional theory (TD-DFT). The in vitro antimicrobial studies of complex 2-5 against an array of microorganisms (bacteria and fungi) were conducted. Complexes 3 and 4 exhibit high dual antibacterial and antifungal activity inhibiting microorganisms possibly via hydrolytic pathway which further evidenced by electrochemical analyses. The complexes 3 and 4 show a high inhibitory activity at 200 μg/ml concentration, suggesting that complexes 3 and 4 are two efficient catalytic inhibitor of microorganisms and further, they should be tested against cancer strains.

  13. Mantle compensation of active metamorphic core complexes at Woodlark rift in Papua New Guinea.

    PubMed

    Abers, Geoffrey A; Ferris, Aaron; Craig, Mitchell; Davies, Hugh; Lerner-Lam, Arthur L; Mutter, John C; Taylor, Brian

    2002-08-22

    In many highly extended rifts on the Earth, tectonic removal of the upper crust exhumes mid-crustal rocks, producing metamorphic core complexes. These structures allow the upper continental crust to accommodate tens of kilometres of extension, but it is not clear how the lower crust and underlying mantle respond. Also, despite removal of the upper crust, such core complexes remain both topographically high and in isostatic equilibrium. Because many core complexes in the western United States are underlain by a flat Moho discontinuity, it has been widely assumed that their elevation is supported by flow in the lower crust or by magmatic underplating. These processes should decouple upper-crust extension from that in the mantle. In contrast, here we present seismic observations of metamorphic core complexes of the western Woodlark rift that show the overall crust to be thinned beneath regions of greatest surface extension. These core complexes are actively being exhumed at a rate of 5-10 km Myr(-1), and the thinning of the underlying crust appears to be compensated by mantle rocks of anomalously low density, as indicated by low seismic velocities. We conclude that, at least in this case, the development of metamorphic core complexes and the accommodation of high extension is not purely a crustal phenomenon, but must involve mantle extension.

  14. Biotinylated Platinum(II) Ferrocenylterpyridine Complexes for Targeted Photoinduced Cytotoxicity.

    PubMed

    Mitra, Koushambi; Shettar, Abhijith; Kondaiah, Paturu; Chakravarty, Akhil R

    2016-06-06

    Biotinylated platinum(II) ferrocenylterpyridine (Fc-tpy) complexes [Pt(Fc-tpy)(L(1))]Cl (1) and [Pt(Fc-tpy)(L(2))]Cl (2), where HL(1) and HL(2) are biotin-containing ligands, were prepared, and their targeted photoinduced cytotoxic effect in cancer cells over normal cells was studied. A nonbiotinylated complex, [Pt(Fc-tpy)(L(3))]Cl (3), was prepared as a control to study the role of the biotin moiety in cellular uptake properties of the complexes. Three platinum(II) phenylterpyridine (Ph-tpy) complexes, viz., [Pt(Ph-tpy)(L(1))]Cl (4), [Pt(Ph-tpy)(L(2))]Cl (5), and [Pt(Ph-tpy)(L(3))]Cl (6), were synthesized and explored to understand the role of a metal-bound Fc-tpy ligand over Ph-tpy as a photoinitiator. The Fc-tpy complexes displayed an intense absorption band near 640 nm, which was absent in their Ph-tpy analogues. The Fc-tpy complexes (1 mM in 0.1 M TBAP) showed an irreversible cyclic voltammetric anodic response of the Fc/Fc(+) couple near 0.25 V. The Fc-tpy complexes displayed photodegradation in red light of 647 nm involving the formation of a ferrocenium ion (Fc(+)) and reactive oxygen species (ROS). Photoinduced release of the biotinylated ligands was observed from spectral measurements, and this possibly led to the controlled generation of an active platinum(II) species, which binds to the calf-thymus DNA used for this study. The biotinylated photoactive Fc-tpy complexes showed significant photoinduced cytotoxicity, giving a IC50 value of ∼7 μM in visible light of 400-700 nm with selective uptake in BT474 cancer cells over HBL-100 normal cells. Furthermore, ferrocenyl complexes resulted in light-induced ROS-mediated apoptosis, as indicated by DCFDA, annexin V/FITC staining, and sub-G1 DNA content determined by fluorescent activated cell sorting analysis. The phenyl analogues 4 and 5 were photostable, served as DNA intercalators, and demonstrated selective cytotoxicity in the cancer cells, giving IC50 values of ∼4 μM.

  15. Spectral studies on Co(II), Ni(II) and Cu(II) complexes with thiosemicarbazone (L1) and semicarbazone (L2) derived from 2-acetyl furan.

    PubMed

    Chandra, Sulekh; Kumar, Anil

    2007-04-01

    Co(II), Ni(II) and Cu(II) complexes are synthesized with thiosemicarbazone (L1) and semicarbazone (L2) derived from 2-acetyl furan. These complexes are characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, mass, IR, electronic and EPR spectral studies. The molar conductance measurements of the complexes in DMSO correspond to non-electrolytic nature except Ni(L)2(NO3)2, which is 1:2 electrolyte. All the complexes are of high-spin type. On the basis of spectral studies an octahedral geometry may be assigned for Co(II) and Ni(II) complexes except nitrato complexes of Ni(II) which is of tetrahedral geometry, whereas tetragonal geometry for Cu(II) complexes.

  16. Electrochemical, catalytic and antimicrobial activities of N-functionalized cyclam based unsymmetrical dicompartmental binuclear nickel(II) complexes

    NASA Astrophysics Data System (ADS)

    Sreedaran, S.; Bharathi, K. Shanmuga; Rahiman, A. Kalilur; Suresh, R.; Jegadeesh, R.; Raaman, N.; Narayanan, V.

    2009-11-01

    Five binuclear nickel(II) complexes have been prepared by simple Schiff base condensation of the compound 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-l,4,8,11-tetraazacyclotetradecane (L) with appropriate aliphatic or aromatic diamine, nickel(II) perchlorate and triethylamine. All the complexes were characterized by elemental and spectral analysis. Positive ion FAB mass spectra show the presence of dinickel core in the complexes. The electronic spectra of the complexes show red shift in the d-d transition. Electrochemical studies of the complexes show two irreversible one electron reduction processes in the range of 0 to -1.4 V. The reduction potential of the complexes shifts towards anodically upon increasing chain length of the macrocyclic ring. All the nickel(II) complexes show two irreversible one electron oxidation waves in the range 0.4-1.6 V. The observed rate constant values for catalysis of the hydrolysis of 4-nitrophenyl phosphate are in the range of 1.36 × 10 -2-9.14 × 10 -2 min -1. The rate constant values for the complexes containing aliphatic diimines are found to be higher than the complexes containing aromatic diimines. Spectral, electrochemical and catalytic studies of the complexes were compared on the basis of increasing chain length of the imine compartment. All the complexes show higher antimicrobial activity than the ligand and metal salt.

  17. Electrochemical studies of DNA interaction and antimicrobial activities of MnII, FeIII, CoII and NiII Schiff base tetraazamacrocyclic complexes

    NASA Astrophysics Data System (ADS)

    Kumar, Anuj; Vashistha, Vinod Kumar; Tevatia, Prashant; Singh, Randhir

    2017-04-01

    Tetraazamacrocyclic complexes of MnII, FeIII, CoII and NiII have been synthesized by template method. These tetraazamacrocycles have been analyzed with various techniques like molar conductance, IR, UV-vis, mass spectral and cyclic voltammetric studies. On the basis of all these studies, octahedral geometry has been assigned to these tetraazamacrocyclic complexes. The DNA binding properties of these macrocyclic complexes have been investigated by electronic absorption spectra, fluorescence spectra, cyclic voltammetric and differential pulse voltammetric studies. The cyclic voltammetric data showed that ipc and ipa were effectively decreased in the presence of calf thymus DNA, which is a strong evidence for the interaction of these macrocyclic complexes with the calf thymus DNA (ct-DNA). The heterogeneous electron transfer rate constant found in the order: KCoII > KNiII > KMnII which indicates that CoII macrocyclic complex has formed a strong intercalated intermediate. The Stern-Volmer quenching constant (KSV) and voltammetric binding constant were found in the order KSV(CoII) > KSV(NiII) > KSV(MnII) and K+(CoII) > K+(NiII) > K+(MnII) which shows that CoII macrocyclic complex exhibits the high interaction affinity towards ct-DNA by the intercalation binding. Biological studies of the macrocyclic complexes compared with the standard drug like Gentamycin, have shown antibacterial activities against E. coli, P. aeruginosa, B. cereus, S. aureus and antifungal activity against C. albicans.

  18. Pentagonal Bipyramid Fe(II) Complexes: Robust Ising-Spin Units towards Heteropolynuclear Nanomagnets.

    PubMed

    Bar, Arun Kumar; Gogoi, Nayanmoni; Pichon, Céline; Goli, V M L Durga Prasad; Thlijeni, Mehrez; Duhayon, Carine; Suaud, Nicolas; Guihéry, Nathalie; Barra, Anne-Laure; Ramasesha, S; Sutter, Jean-Pascal

    2017-01-24

    Pentagonal bipyramid Fe(II) complexes have been investigated to evaluate their potential as Ising-spin building units for the preparation of heteropolynuclear complexes that are likely to behave as single-molecule magnets (SMMs). The considered monometallic complexes were prepared from the association of a divalent metal ion with pentadentate ligands that have a 2,6-diacetylpyridine bis(hydrazone) core (H2 L(N3O2R) ). Their magnetic anisotropy was established by magnetometry to reveal their zero-field splitting (ZFS) parameter D, which ranged between -4 and -13 cm(-1) and was found to be modulated by the apical ligands (ROH versus Cl). The alteration of the D value by N-bound axial CN ligands, upon association with cyanometallates, was also assessed for heptacoordinated Fe(II) as well as for related Ni(II) and Co(II) derivatives. In all cases, N-coordinated cyanide ligands led to large magnetic anisotropy (i.e., -8 to -18 cm(-1) for Fe and Ni, +33 cm(-1) for Co). Ab initio calculations were performed on three Fe(II) complexes, which enabled one to rationalize the role of the ligand on the nature and magnitude of the magnetic anisotropy. Starting from the pre-existing heptacoordinated complexes, a series of pentanuclear compounds were obtained by reactions with paramagnetic [W(CN)8 ](3-) . Magnetic studies revealed the occurrence of ferromagnetic interactions between the spin carriers in all the heterometallic systems. Field-induced slow magnetic relaxation was observed for mononuclear Fe(II) complexes (Ueff /kB up to 53 K (37 cm(-1) ), τ0 =5×10(-9)  s), and SMM behavior was evidenced for a heteronuclear [Fe3 W2 ] derivative (Ueff /kB =35 K and τ0 =4.6 10(-10)  s), which confirmed that the parent complexes were robust Ising-type building units. High-field EPR spectroscopic investigation of the ZFS parameters for a Ni derivative is also reported.

  19. Synthesis and crystal structure of thiosemicarbazide complexes of nickel(II) and copper(II)

    NASA Astrophysics Data System (ADS)

    Sadikov, G. G.; Antsyshkina, A. S.; Koksharova, T. V.; Sergienko, V. S.; Kurando, S. V.; Gritsenko, I. S.

    2012-07-01

    Thiosemicarbazide complexes of nickel(II) [Ni( TSC)2](H Sal)2 ( I) and copper(II) [Cu( TSC)2](H Sal)2 ( Ia) ( TSC is thiosemicarbazide and H Sal is a salycilate anion), as well as complexes [Ni( TSC)2](SO4) · 2H2O ( II) and [Ni( TSC)3]Cl2 · H2O ( III), are synthesized and characterized by IR spectroscopy and X-ray diffraction. Monoclinic crystals I and Ia are isostructural; space group P21/ n, Z = 2. Crystals II are monoclinic, space group P21/ m, Z = 2. Crystals III are orthorhombic, space group Pbca, Z = 8. In I and Ia, two planar salycilate anions sandwich a planar centrosymmetric [Ni( TSC)2]2+ cation to form a supermolecule. The cation and anions are additionally bound by hydrogen bonds. Other hydrogen bonds connect supermolecules into planar layers. In structure II, centrosymmetric [Ni( TSC)2]2+ cations are connected by π-stacking interactions into supramolecular ensembles of a specific type. The ensembles, water molecules, and (SO4)2- anions are bound in the crystal via hydrogen bonds. In the [Ni( TSC)3]2+ cation of structure III, ligands coordinate the Ni atom by the bidentate chelate pattern with the formation of five-membered metallocycles. These metallocycles have an envelope conformation unlike those in I and II, which are planar. In III (unlike in analogous complexes), a meridional isomer of the coordination octahedron of the Ni atom is formed. Together with Cl1- and Cl2- anions, cations form supermolecules, which are packed into planar layers with a square-cellular structure. The layers are linked by hydrogen bonds formed by crystallization water molecules that are located between the layers.

  20. Organometallic osmium(II) arene anticancer complexes containing picolinate derivatives.

    PubMed

    van Rijt, Sabine H; Peacock, Anna F A; Johnstone, Russell D L; Parsons, Simon; Sadler, Peter J

    2009-02-16

    Chlorido osmium(II) arene [(eta(6)-biphenyl)Os(II)(X-pico)Cl] complexes containing X = Br (1), OH (2), and Me (3) as ortho, or X = Cl (4), CO(2)H (5), and Me (6) as para substituents on the picolinate (pico) ring have been synthesized and characterized. The X-ray crystal structures of 1 and 6 show typical "piano-stool" geometry with intermolecular pi-pi stacking of the biphenyl outer rings of 6. At 288 K the hydrolysis rates follow the order 2 > 6 > 4 > 3 > 5 > 1 with half-lives ranging from minutes to 4.4 h illustrating the influence of both electronic and steric effects of the substituents. The pK(a) values of the aqua adducts 3A, 4A, 5A, and 6A were all in the range of 6.3-6.6. The para-substituted pico complexes 4-6 readily formed adducts with both 9-ethyl guanine (9EtG) and 9-ethyl adenine (9EtA), but these were less favored for the ortho-substituted complexes 1 and 3 showing little reaction with 9EtG and 9EtA, respectively. Density-functional theory calculations confirmed the observed preferences for nucleobase binding for complex 1. In cytotoxicity assays with A2780, cisplatin-resistant A2780cis human ovarian, A549 human lung, and HCT116 colon cancer cells, only complexes 4 (p-Cl) and 6 (p-Me) exhibited significant activity (IC(50) values < 25 microM). Both of these complexes were as active as cisplatin in A2780 (ovarian) and HCT116 (colon) cell lines, and even overcome cisplatin resistance in the A2780cis (ovarian) cell line. The inactivity of 5 is attributed to the negative charge on its para carboxylate substituent. These data illustrate how the chemical reactivity and cancer cell cytotoxicity of osmium arene complexes can be controlled and "fine-tuned" by the use of steric and electronic effects of substituents on a chelating ligand to give osmium(II) arene complexes which are as active as cisplatin but have a different mechanism of action.

  1. TFIIH phosphorylation of the Pol II CTD stimulates Mediator dissociation from the preinitiation complex and promoter escape

    PubMed Central

    Wong, Koon Ho; Jin, Yi; Struhl, Kevin

    2014-01-01

    The transition between transcriptional initiation and elongation by RNA polymerase (Pol) II is associated with phosphorylation of its C-terminal tail (CTD). Depletion of Kin28, the TFIIH subunit that phosphorylates the CTD, does not affect elongation but causes Pol II occupancy profiles to shift upstream in a FACT-independent manner indicative of a defect in promoter escape. Stronger defects in promoter escape are linked to stronger effects on preinitiation complex formation and transcription, suggesting that impairment in promoter escape results in premature dissociation of general factors and Pol II near the promoter. Kin28 has a stronger effect on genes whose transcription is dependent on SAGA as opposed to TFIID. Strikingly, Kin28 depletion causes a dramatic increase in Mediator at the core promoter. These observations suggest that TFIIH phosphorylation of the CTD causes Mediator dissociation, thereby permitting rapid promoter escape of Pol II from the preinitiation complex. PMID:24746699

  2. North Atlantic simulations in Coordinated Ocean-ice Reference Experiments phase II (CORE-II). Part I: Mean states

    NASA Astrophysics Data System (ADS)

    Danabasoglu, Gokhan; Yeager, Steve G.; Bailey, David; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Böning, Claus; Bozec, Alexandra; Canuto, Vittorio M.; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Danilov, Sergey; Diansky, Nikolay; Drange, Helge; Farneti, Riccardo; Fernandez, Elodie; Fogli, Pier Giuseppe; Forget, Gael; Fujii, Yosuke; Griffies, Stephen M.; Gusev, Anatoly; Heimbach, Patrick; Howard, Armando; Jung, Thomas; Kelley, Maxwell; Large, William G.; Leboissetier, Anthony; Lu, Jianhua; Madec, Gurvan; Marsland, Simon J.; Masina, Simona; Navarra, Antonio; George Nurser, A. J.; Pirani, Anna; y Mélia, David Salas; Samuels, Bonita L.; Scheinert, Markus; Sidorenko, Dmitry; Treguier, Anne-Marie; Tsujino, Hiroyuki; Uotila, Petteri; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang

    2014-01-01

    Simulation characteristics from eighteen global ocean-sea-ice coupled models are presented with a focus on the mean Atlantic meridional overturning circulation (AMOC) and other related fields in the North Atlantic. These experiments use inter-annually varying atmospheric forcing data sets for the 60-year period from 1948 to 2007 and are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The protocol for conducting such CORE-II experiments is summarized. Despite using the same atmospheric forcing, the solutions show significant differences. As most models also differ from available observations, biases in the Labrador Sea region in upper-ocean potential temperature and salinity distributions, mixed layer depths, and sea-ice cover are identified as contributors to differences in AMOC. These differences in the solutions do not suggest an obvious grouping of the models based on their ocean model lineage, their vertical coordinate representations, or surface salinity restoring strengths. Thus, the solution differences among the models are attributed primarily to use of different subgrid scale parameterizations and parameter choices as well as to differences in vertical and horizontal grid resolutions in the ocean models. Use of a wide variety of sea-ice models with diverse snow and sea-ice albedo treatments also contributes to these differences. Based on the diagnostics considered, the majority of the models appear suitable for use in studies involving the North Atlantic, but some models require dedicated development effort.

  3. Biogenesis of photosystem II complexes: transcriptional, translational, and posttranslational regulation

    PubMed Central

    1986-01-01

    The integral membrane proteins of photosystem II (PS II) reaction center complexes are encoded by chloroplast genomes. These proteins are absent from thylakoids of PS II mutants of algae and vascular plants as a result of either chloroplast or nuclear gene mutations. To resolve the molecular basis for the concurrent absence of the PS II polypeptides, protein synthesis rates and mRNA levels were measured in mutants of Chlamydomonas reinhardtii that lack PS II. The analyses show that one nuclear gene product regulates the levels of transcripts from the chloroplast gene encoding the 51-kD chlorophyll a-binding polypeptide (polypeptide 5) but is not involved in the synthesis of other chloroplast mRNAs. Another nuclear product is specifically required for translation of mRNA encoding the 32-34-kD polypeptide, D1. The absence of either D1 or polypeptide 5 does not eliminate the synthesis and thylakoid insertion of two other integral membrane proteins of PS II, the chlorophyll a-binding polypeptide of 46 kD (polypeptide 6) and the 30-kD "D1-like" protein, D2. However, these two unassembled subunits cannot be properly processed and/or are degraded in the mutants even though they reside in the membrane. In addition, pulse labeling of the nuclear mutants and a chloroplast mutant that does not synthesize D1 mRNA indicates that synthesis of polypeptide 5 and D1 is coordinated at the translational level. A model is presented to explain how absence of one of the two proteins could lead to translational arrest of the other. PMID:3533953

  4. Mercury(II) Penicillamine Complex Formation in Alkaline Aqueous Solution

    SciTech Connect

    Leung, B.O.; Jalilehvand, F.; Mah, V.

    2009-06-01

    The complex formation between mercury(II) and penicillamine (H{sub 2}Pen = 3,3'-dimethyl cysteine) in alkaline aqueous solutions (pH {approx}2) has been investigated with extended X-ray absorption fine structure (EXAFS) and {sup 199}Hg NMR spectroscopy. By varying the penicillamine concentration (C{sub H{sub 2}Pen} = 0.2--1.25 M) in {approx}0.1 M Hg(II) solutions, two coexisting major species [Hg(Pen){sub 2}]{sup 2-} and [Hg(Pen){sub 3}]{sub 4-} were characterized with mean Hg-S bond distances 2.34(2) and 2.44(2) {angstrom}, respectively. The [Hg(Pen){sub 2}]{sup 2-} complex with two deprotonated penicillamine ligands forms an almost linear S-Hg-S entity with two weak chelating Hg-N interactions at the mean Hg-N distance 2.52(2) {angstrom}. The same type of coordination is also found for the corresponding [Hg(Cys){sub 2}]{sup 2-} complex in alkaline aqueous solution with the mean bond distances Hg-S 2.34(2) {angstrom} and Hg-N 2.56(2) {angstrom}. The relative amounts of the [Hg(Pen){sub 2}]{sup 2-} and [Hg(Pen){sub 3}]{sup 4-} complexes were estimated by fitting linear combinations of the EXAFS oscillations to the experimental spectra. Also their {sup 199}Hg NMR chemical shifts were used to evaluate the complex formation, showing that the [Hg(Pen){sub 3}]{sup 4-} complex dominates already at moderate excess of the free ligand ([Pen{sup 2-}] > {approx} 0.1 M).

  5. EXAFS spectra using synchrotron radiation of Cu (II) complexes

    NASA Astrophysics Data System (ADS)

    Ninama, Samrath; Mishra, A.

    2016-10-01

    EXAFS analysis of Cu (II) complex as a ligand of 2-methyl-3-[(bis-aniline(R) phenyl]- 3H-1, 5 benzodiazepine. Extended X-ray absorption fine structure (EXAFS) spectra have been recorded at the K-edge of Cu (II) using the energy dispersive EXAFS beam line at 2.5GeV Indus - 2 synchrotron source at RRCAT, Indore, India. A theoretical EXAFS data analysis is also carried out by Fourier analysis of experimental EXAFS data of the copper (II) complexes. This analysis includes details of the Fourier transform of the data and the extraction of metal-ligand bond length. Bond lengths determined from data analysis methods are compared with the bond lengths obtained from several other known techniques, namely, Levy's, Lytle's and Lytle, Sayers and Stern's (LSS) methods. These data have also been calibrated by derivative method and bond lengths have also been obtained from Fourier transformation method and the results have been compared with the each other. The EXAFS data have been analyzed using the computer software Athena.

  6. On the association between core-collapse supernovae and H ii regions

    NASA Astrophysics Data System (ADS)

    Crowther, Paul A.

    2013-01-01

    Previous studies of the location of core-collapse supernovae (ccSNe) in their host galaxies have variously claimed an association with H ii regions; no association or an association only with hydrogen-deficient ccSNe. Here, we examine the immediate environments of 39 ccSNe whose positions are well known in nearby (≤15 Mpc), low-inclination (≤65°) hosts using mostly archival, continuum-subtracted Hα ground-based imaging. We find that 11 out of 29 hydrogen-rich ccSNe are spatially associated with H ii regions (38 ± 11 per cent), versus 7 out of 10 hydrogen-poor ccSNe (70 ± 26 per cent). Similar results from Anderson et al. led to an interpretation that the progenitors of Type Ib/c ccSNe are more massive than those of Type II ccSNe. Here, we quantify the luminosities of H ii region either coincident with or nearby to the ccSNe. Characteristic nebulae are long-lived (˜20 Myr) giant H ii regions rather than short-lived (˜4 Myr) isolated, compact H ii regions. Therefore, the absence of an H ii region from most Type II ccSNe merely reflects the longer lifetime of stars with ⪉12 M⊙ than giant H ii regions. Conversely, the association of an H ii region with most Type Ib/c ccSNe is due to the shorter lifetime of stars with >12 M⊙ stars than the duty cycle of giant H ii regions. Therefore, we conclude that the observed association between certain ccSNe and H ii provides only weak constraints upon their progenitor masses. Nevertheless, we do favour lower mass progenitors for two Type Ib/c ccSNe that lack associated nebular emission, a host cluster or a nearby giant H ii region. Finally, we also reconsider the association between long gamma-ray bursts and the peak continuum light from their (mostly) dwarf hosts, and conclude that this is suggestive of very high mass progenitors, in common with previous studies.

  7. Refactoring the Six-Gene Photosystem II Core in the Chloroplast of the Green Algae Chlamydomonas reinhardtii.

    PubMed

    Gimpel, Javier A; Nour-Eldin, Hussam H; Scranton, Melissa A; Li, Daphne; Mayfield, Stephen P

    2016-07-15

    Oxygenic photosynthesis provides the energy to produce all food and most of the fuel on this planet. Photosystem II (PSII) is an essential and rate-limiting component of this process. Understanding and modifying PSII function could provide an opportunity for optimizing photosynthetic biomass production, particularly under specific environmental conditions. PSII is a complex multisubunit enzyme with strong interdependence among its components. In this work, we have deleted the six core genes of PSII in the eukaryotic alga Chlamydomonas reinhardtii and refactored them in a single DNA construct. Complementation of the knockout strain with the core PSII synthetic module from three different green algae resulted in reconstitution of photosynthetic activity to 85, 55, and 53% of that of the wild-type, demonstrating that the PSII core can be exchanged between algae species and retain function. The strains, synthetic cassettes, and refactoring strategy developed for this study demonstrate the potential of synthetic biology approaches for tailoring oxygenic photosynthesis and provide a powerful tool for unraveling PSII structure-function relationships.

  8. Mn(II) and Cu(II) complexes of a dithiadiazolyl radical ligand: monomer/dimer equilibria in solution.

    PubMed

    Britten, James; Hearns, Nigel G R; Preuss, Kathryn E; Richardson, John F; Bin-Salamon, Sofi

    2007-05-14

    Complexes of the 4-(2'-pyridyl)-1,2,3,5-dithiadiazolyl radical bidentate ligand with bis(hexafluoroacetylacetonato)manganese(II) and with bis(hexafluoroacetylacetonato)copper(II) have been prepared. Unlike the previously reported cobalt(II) complex, these complexes form dimers via intermolecular S...S contacts in the solid state. The spectroscopic and magnetic properties of these species in the solid state and in solution are reported and compared to the previously reported Co(II) complex, with emphasis on the elucidation of the a monomer/dimer equilibrium in the solution. The electrochemical properties of these species in solution are also presented and discussed.

  9. Platinum(II) 1,5-COD oxo complexes

    SciTech Connect

    Shan, H.; James, A.; Sharp, P.R.

    1998-11-02

    Three new types of platinum(II) oxo complexes--[(1,5-COD)Pt({mu}{sup 3}-O)(AuL)]{sub 2}(BF{sub 4}){sub 2} [1, L = PPh{sub 3}, PPh{sub 2}Et, PPh{sub 2}-i-Pr, P(o-tol){sub 3}, P(p-tol){sub 3}, P(p-MeOC{sub 6}H{sub 4}){sub 3}, P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}], [(1,5-COD)Pt{l_brace}{mu}{sup 3}-O(AuL){sub 2}{r_brace}{sub 2}](BF{sub 4}){sub 2} (2), and [(1,5-COD){sub 4}Pt{sub 4}({mu}{sup 3}-O){sub 2}Cl{sub 2}]X{sub 2} (3, X = BF{sub 4}; 3a, X = CF{sub 3}SO{sub 3})--are obtained from oxo/chloro exchange reactions between (1,5-COD)PtCl{sub 2} and [(LAu){sub 3}({mu}{sup 3}-O)]BF{sub 4}. Crystals of 1 (L = PPh{sub 3}) from CDCl{sub 3} are triclinic. Crystals of 3a from CH{sub 2}Cl{sub 2}/toluene are trigonal. The structure of the cationic portion of 1 shows a planar (COD)-Pt({mu}-O){sub 2}Pt(COD) unit with slightly out-of-plane LAu{sup +} groups linearly coordinated to the oxo ligands. The structure of the cationic portion of 3a is similar and shows a slightly folded (COD)Pt({mu}-O){sub 2}Pt(COD) unit with out-of-plane [(COD)PtCl]{sup +} groups coordinated to the oxo ligands. Solutions of 3 in untreated CH{sub 2}Cl{sub 2} or CD{sub 2}Cl{sup 2} deposit crystals of [(1,5-COD){sub 4}Pt{sub 4}({mu}{sup 3}-O){sub 2}({mu}{sup 2}-OH)](BF{sub 4}){sub 3} (4) which are monoclinic. The core structure of the cationic portion of 4 shows a tetranuclear platinum cation in which the metal atoms occupy the corners of a distorted tetrahedron and two {mu}{sup 3}-oxo ligands and one {mu}{sup 2}-hydroxo ligand bridge the four platinum atoms. Reaction of 1 (L = PPh{sub 3}) with PPh{sub 3} gives OPPh{sub 3} and [(Ph{sub 3}P){sub 3}PtAuPPh{sub 3}]BF{sub 4} (5) which is also obtained from (Ph{sub 3}P){sub 4}Pt and Ph{sub 3}-PAuBF{sub 4}. Crystals of 5 from THF are monoclinic. The structure of 5 consists of an L{sub 3}Pt-AuL cation where the Au atom is linear 2-coordinate and the Pt atom is distorted square-planar 4-coordinate.

  10. Photochemical and thermal hydrogen production from water catalyzed by carboxylate-bridged dirhodium(II) complexes.

    PubMed

    Tanaka, Saya; Masaoka, Shigeyuki; Yamauchi, Kosei; Annaka, Masahiko; Sakai, Ken

    2010-12-14

    A series of dinuclear Rh(II) complexes, [Rh(2)(μ-OAc)(4)(H(2)O)(2)] (HOAc = acetic acid) (1), [Rh(2)(μ-gly)(4)(H(2)O)(2)] (Hgly = glycolic acid) (2), [Rh(2)(μ-CF(3)CO(2))(4)(acetone)(2)] (3), and [Rh(2)(bpy)(2)(μ-OAc)(2)(OAc)(2)] (4), were found to serve as H(2)-evolving catalysts in a three-component system consisting of tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)(3)(2+)), methylviologen (MV(2+)), and ethylenediaminetetraacetic acid disodium salt (EDTA). It was also confirmed that thermal reduction of water into H(2) by MV(+)˙, in situ generated by the bulk electrolysis of MV(2+), is effectively promoted by 1 as a H(2)-evolving catalyst. The absorption spectra of the photolysis solution during the photocatalysis were monitored up to 6 h to reveal that the formation of photochemical or thermal byproducts of MV(+)˙ is dramatically retarded in the presence of the Rh(II)(2) catalysts, for the H(2) formation rather than the decomposition of MV(+)˙ becomes predominant in the presence of the Rh(II)(2) catalysts. The stability of the Rh(II)(2) dimers was confirmed by absorption spectroscopy, (1)H NMR, and ESI-TOF mass spectroscopy. The results indicated that neither elimination nor replacement of the equatorial ligands take place during the photolysis, revealing that one of the axial sites of the Rh(2) core is responsible for the hydrogenic activation. The quenching of Ru*(bpy)(3)(2+) by 1 was also investigated by luminescence spectroscopy. The rate of H(2) evolution was found to decrease upon increasing the concentration of 1, indicating that the quenching of Ru*(bpy)(3)(2+) by the Rh(ii)(2) species rather than by MV(2+) becomes predominant at the higher concentrations of 1. The DFT calculations were carried out for several possible reaction paths proposed (e.g., [Rh(II)(2)(μ-OAc)(4)(H(2)O)] + H(+) and [Rh(II)(2)(μ-OAc)(4)(H(2)O)] + H(+) + e(-)). It is suggested that the initial step is a proton-coupled electron transfer (PCET) to the Rh(II)(2) dimer leading to

  11. IR and ESR study of Cu(II)-nitrazepam complexes

    NASA Astrophysics Data System (ADS)

    Forizs, E.; David, L.; Cozar, O.; Crăciun, C.; Venter, M.; Kilyen, M.

    1997-06-01

    The CuL 2X 2 (L = 7-nitro-1,3-dihydro-5-phenyl-2 H-1,4-benzodiazepin-2-one, known as nitrazepam, X = Cl, Br) complexes were prepared and investigated by IR, ESR and magnetic susceptibility measurements. The IR spectra suggest that the Cu(II) ion is coordinated by two nitrogen and two halogen atoms. The powder ESR spectrum at room temperature of CuL 2Br 2 is quasiisotropic, while that of CuL 2Cl 2 is characteristic of an axial monomeric species with small rhombic distortions. The isotropic ESR spectra of these compounds in DMF and Py solutions suggest the presence of pseudo-tetrahedral monomeric species. Two different monomeric species were evidenced in Cu(II)-nitrazepam solutions adsorbed onto NaY zeolite.

  12. Physical and functional crosstalk between Fanconi anemia core components and the GINS replication complex.

    PubMed

    Tumini, Emanuela; Plevani, Paolo; Muzi-Falconi, Marco; Marini, Federica

    2011-02-07

    Fanconi anemia (FA) is an inherited disease characterized by bone marrow failure, increased cancer risk and hypersensitivity to DNA cross-linking agents, implying a role for this pathway in the maintenance of genomic stability. The central player of the FA pathway is the multi-subunit E3 ubiquitin ligase complex activated through a replication- and DNA damage-dependent mechanism. A consequence of the activation of the complex is the monoubiquitylation of FANCD2 and FANCI, late term effectors in the maintenance of genome integrity. The details regarding the coordination of the FA-dependent response and the DNA replication process are still mostly unknown. We found, by yeast two-hybrid assay and co-immunoprecipitation in human cells, that the core complex subunit FANCF physically interacts with PSF2, a member of the GINS complex essential for both the initiation and elongation steps of DNA replication. In HeLa cells depleted for PSF2, we observed a decreased binding to chromatin of the FA core complex, suggesting that the GINS complex may have a role in either loading or stabilizing the FA core complex onto chromatin. Consistently, GINS and core complex bind chromatin contemporarily upon origin firing and PSF2 depletion sensitizes cells to DNA cross-linking agents. However, depletion of PSF2 is not sufficient to reduce monoubiquitylation of FANCD2 or its localization to nuclear foci following DNA damage. Our results suggest a novel crosstalk between DNA replication and the FA pathway.

  13. Challenging the Research Base of the Common Core State Standards: A Historical Reanalysis of Text Complexity

    ERIC Educational Resources Information Center

    Gamson, David A.; Lu, Xiaofei; Eckert, Sarah Anne

    2013-01-01

    The widely adopted Common Core State Standards (CCSS) call for raising the level of text complexity in textbooks and reading materials used by students across all grade levels in the United States; the authors of the English Language Arts component of the CCSS build their case for higher complexity in part upon a research base they say shows a…

  14. Student Reading Growth Illuminates the Common Core Text-Complexity Standard: Raising Both Bars

    ERIC Educational Resources Information Center

    Williamson, Gary L.; Fitzgerald, Jill; Stenner, Jackson A.

    2014-01-01

    The Common Core State Standards (CCSS) establish a challenging text-complexity standard for all high school graduates to read at college and workplace text-complexity levels. We argue that implementation of the CCSS standard requires concurrent examination of historical student reading-growth trends. An example of a historical student average…

  15. Pd(II) complexes of acetylcholinesterase reactivator obidoxime

    PubMed Central

    Stoykova, Silviya; Atanasov, Vasil; Pantcheva, Ivayla; Antonov, Liudmil

    2014-01-01

    The ability of the acetylcholinesterase reactivator obidoxime (H2L2+) to bind palladium(II) cations was evaluated spectrophotometrically at different reaction conditions (pH, reaction time, metal-to-ligand molar ratio). The results showed that immediately after mixing the reagents, pH 7.4, complex species of composition [PdHL]3+ existed predominantly with a value of conditional stability constant lgβ‘=6.52. The reaction was completed within 24 hours affording the formation of species [Pd2L]4+ with significantly increased stability (lgβ‘=9.34). The spectral data suggest that obidoxime coordinates metal(II) ions through the oximate functional groups. The in vitro reactivation assay of paraoxon-inhibited rat brain acetylcholinesterase revealed that the new complex species were much less active than the non-coordinated obidoxime. The lack of reactivation ability could be explained by the considerable stability of complexes in solution as well as by the deprotonation of oxime groups essential for recovery of the enzymatic activity. PMID:26109891

  16. Platinum(II) complexes as spectroscopic probes for biomolecules

    SciTech Connect

    Ratilla, E.

    1990-09-21

    The use of platinum(II) complexes as tags and probes for biomolecules is indeed advantageous for their reactivities can be selective for certain purposes through an interplay of mild reaction conditions and of the ligands bound to the platinum. The use of {sup 195}Pt NMR as a method of detecting platinum and its interactions with biomolecules was carried out with the simplest model of platinum(II) tagging to proteins. Variable-temperature {sup 195}Pt NMR spectroscopy proved useful in studying the stereodynamics of complex thioethers like methionine. The complex, Pt(trpy)Cl{sup +}, with its chromophore has a greater potential for probing proteins. It is a noninvasive and selective tag for histidine and cysteine residues on the surface of cytochrome c at pH 5. The protein derivatives obtained are separable, and the tags are easily quantitated and differentiated through the metal-to-ligand charge transfer bands which are sensitive to the environment of the tag. Increasing the pH to 7.0 led to the modification by Pt(trpy)Cl{sup +}of Arg 91 in cytochrome c. Further studies with guanidine-containing ligands as models for arginine modification by Pt(trpy)Cl{sup +} showed that guanidine can act as a terminal ligand and as a bridging ligand. Owing to the potential utility of Pt(trpy)L{sup n+} as electron dense probes of nucleic acid structure, interactions of this bis-Pt(trpy){sup 2+} complex with nucleic acids was evaluated. Indeed, the complex interacts non-covalently with nucleic acids. Its interactions with DNA are not exactly the same as those of its precedents. Most striking is its ability to form highly immobile bands of DNA upon gel electrophoresis. 232 refs.

  17. Thermodynamics for complex formation between palladium(ii) and oxalate.

    PubMed

    Pilný, Radomír; Lubal, Přemysl; Elding, Lars I

    2014-08-28

    Complex formation between [Pd(H2O)4](2+) and oxalate (ox = C2O4(2-)) has been studied spectrophoto-metrically in aqueous solution at variable temperature, ionic strength and pH. Thermodynamic parameters at 298.2 K and 1.00 mol dm(-3) HClO4 ionic medium for the complex formation [Pd(H2O)4](2+) + H2ox ⇄ [Pd(H2O)2(ox)] + 2H3O(+) with equilibrium constant K1,H (in mol dm(-3)) are log10K1,H = 3.38 ± 0.08, ΔH = -33 ± 3 kJ mol(-1), and ΔS = -48 ± 11 J K(-1) mol(-1), as determined from spectrophotometric equilibrium titrations at 15.0, 20.0, 25.0 and 31.0 °C. Thermodynamic overall stability constants β (in (mol dm(-3))(-n), n = 1,2) for [Pd(H2O)2(ox)] and [Pd(ox)2](2-) at zero ionic strength and 298.2 K, defined as the equilibrium constants for the reaction Pd(2+) + nox(2-) ⇄ [Pd(ox)n](2-2n) (water molecules omitted) are log10β = 9.04 ± 0.06 and log10β = 13.1 ± 0.3, respectively, calculated by use of Specific Ion Interaction Theory from spectrophotometric titrations with initial hydrogen ion concentrations of 1.00, 0.100 and 0.0100 mol dm(-3) and ionic strengths of 1.00, 2.00 or 3.00 mol dm(-3). The values derived together with literature data give estimated overall stability constants for Pd(ii) compounds such as [Pd(en)(ox)] and cis-[Pd(NH3)2Cl2], some of them analogs to Pt(ii) complexes used in cancer treatment. The palladium oxalato complexes are significantly more stable than palladium(ii) complexes with monodentate O-bonding ligands. A comparison between several different palladium complexes shows that different parameters contribute to the stability variations observed. These are discussed together with the so-called chelate effect.

  18. Graphene-Ruthenium(II) complex composites for sensitive ECL immunosensors.

    PubMed

    Xiao, Fang-Nan; Wang, Min; Wang, Feng-Bin; Xia, Xing-Hua

    2014-02-26

    Non-covalent modification method has been proven as an effective strategy for enhancing the chemical properties of graphene while the structure and electronic properties of graphene can be retained. This work describes a novel strategy to fabricate a solid-state electrochemiluminescent (ECL) immunosensor based on ruthenium(II) complex/3,4,9,10-perylenetetracarboxylic acid (PTCA)/graphene nanocomposites (Ru-PTCA/G) for sensitive detection of α-fetoprotein (AFP). It is found that immobilization of PTCA and reduction of GO can be simultaneously achieved in one-pot synthesis method under alkaline condition and moderate temperature, forming PTCA/G nanocomposites. Further covalent attachment of ruthenium(II) complex to the PTCA assembled on graphene sheets produces the functional Ru-PTCA/G nanocomposites which show good electrochemical activity and ca. 21 times higher luminescence quantum efficiency than the adsorbed derivative ruthenium(II) complex. The Ru-PTCA/G nanocomposites based solid-state ECL sensor exhibits high stability toward the determination of tripropylamine (TPA) coreactant. In addition, a new ECL immunosensor based on steric hindrance effect is fabricated by cross-linking α-fetoprotein antibody (anti-AFP) with chitosan covered on Ru-PTCA/G composites modified electrode for detection of cancer biomarker AFP. This ECL immunosensor shows an extremely sensitive response to AFP in a linear range of 5 pg·mL(-1) -10 ng·mL(-1) with a detection limit of 0.2 pg·mL(-1) . The present approach is effective for various molecules immobilization and may become a promising technique for biomolecular detection.

  19. Preparation and reactivity of a tetranuclear Fe(II) core in the metallothionein α-domain.

    PubMed

    Sano, Yohei; Onoda, Akira; Sakurai, Rie; Kitagishi, Hiroaki; Hayashi, Takashi

    2011-05-01

    Metallothioneins (MTs) are small cysteine-rich proteins which exhibit high affinities for various metal ions and play roles in storage of essential metals and detoxification of toxic metals. Studies on the redox properties of MTs have been quite limited. Recently, we focused on the α-domain of MT (MTα) as a protein matrix and incorporated a tetranuclear metal cluster as a reductant. UV-visible, CD and MS data indicate the formation of the stable tetranuclear metal-cysteine cluster in the MTα matrix with Fe(II)(4)-MTα and Co(II)(4)-MTα species existing in water. Furthermore, the Fe(II)(4)-MTα species was found to promote the reduction of met-myoglobin and azobenzene derivatives under mild conditions. Particularly, the stoichiometric reduction of methyl red with Fe(II)(4)-MTα (1:1) was found to proceed with a conversion of 98% over a period of 6h at 25°C. This indicates that all of the four Fe(II) cores contribute to the reduction. In this paper, we describe the preparation and reactivity of the tetranuclear iron cluster in the protein matrix.

  20. Antitumor activity of phenylene bridged binuclear bis(imino-quinolyl)palladium(II) and platinum(II) complexes.

    PubMed

    Motswainyana, William M; Onani, Martin O; Madiehe, Abram M; Saibu, Morounke

    2014-04-01

    Antitumor effects of a known bis(imino-quinolyl)palladium(II) complex 1 and its newly synthesized platinum(II) analogue 2 were evaluated against human breast (MCF-7) and human colon (HT-29) cancer cell lines. The complexes gave cytotoxicity profiles that were better than the reference drug cisplatin. The highest cytotoxic activities were pronounced in complex 2 across the two examined cancer cell lines. Both compounds represent potential active drugs based on bimetallic complexes.

  1. Assembly and properties of heterobimetallic Co(II/III)/Ca(II) complexes with aquo and hydroxo ligands.

    PubMed

    Lacy, David C; Park, Young Jun; Ziller, Joseph W; Yano, Junko; Borovik, A S

    2012-10-24

    The use of water as a reagent in redox-driven reactions is advantageous because it is abundant and environmentally compatible. The conversion of water to dioxygen in photosynthesis illustrates one example, in which a redox-inactive Ca(II) ion and four manganese ions are required for function. In this report we describe the stepwise formation of two new heterobimetallic complexes containing Co(II/III) and Ca(II) ions and either hydroxo or aquo ligands. The preparation of a four-coordinate Co(II) synthon was achieved with the tripodal ligand, N,N',N"-[2,2',2"-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamido, [MST](3-). Water binds to [Co(II)MST](-) to form the five-coordinate [Co(II)MST(OH(2))](-) complex that was used to prepare the Co(II)/Ca(II) complex [Co(II)MST(μ-OH(2))Ca(II)⊂15-crown-5(OH(2))](+) ([Co(II)(μ-OH(2))Ca(II)OH(2)](+)). [Co(II)(μ-OH(2))CaOH(2)](+) contained two aquo ligands, one bonded to the Ca(II) ion and one bridging between the two metal ions, and thus represents an unusual example of a heterobimetallic complex containing two aquo ligands spanning different metal ions. Both aquo ligands formed intramolecular hydrogen bonds with the [MST](3-) ligand. [Co(II)MST(OH(2))](-) was oxidized to form [Co(III)MST(OH(2))] that was further converted to [Co(III)MST(μ-OH)Ca(II)⊂15-crown-5](+) ([Co(III)(μ-OH)Ca(II)](+)) in the presence of base and Ca(II)OTf(2)/15-crown-5. [Co(III)(μ-OH)Ca(II)](+) was also synthesized from the oxidation of [Co(II)MST](-) with iodosylbenzene (PhIO) in the presence of Ca(II)OTf(2)/15-crown-5. Allowing [Co(III)(μ-OH)Ca(II)](+) to react with diphenylhydrazine afforded [Co(II)(μ-OH(2))Ca(II)OH(2)](+) and azobenzene. Additionally, the characterization of [Co(III)(μ-OH)Ca(II)](+) provides another formulation for the previously reported Co(IV)-oxo complex, [(TMG(3)tren)Co(IV)(μ-O)Sc(III)(OTf)(3)](2+) to one that instead could contain a Co(III)-OH unit.

  2. Comparisons of MgII core-wing data with Ground-Based Ca K-line

    NASA Astrophysics Data System (ADS)

    Chapman, G. A.; Preminger, D.

    2011-12-01

    Magnesium_II core-wing ratio data will be compared with ground-based K-line photometry for most of cycle 22 and 23. The ground-based data is the photmetric sum computed from the composite K-line obtained from the San Fernando Observatory. We will examine several MgII core-wing composites. This work is partially supported by grants NNX11AB51G from NASA and ATM-0848518 from NSF.

  3. HSDP II Drill Core: Preliminary Rock Strength Results and Implications to Flank Stability, Mauna Kea Volcano

    NASA Astrophysics Data System (ADS)

    Thompson, N.; Watters, R. J.; Schiffman, P.

    2004-12-01

    Selected portions of the 3-km HSDP II core were tested to provide unconfined rock strength data from hyaloclastite alteration zones and pillow lavas. Though the drilling project was not originally intended for strength purpose, it is believed the core can provide unique rock strength insights into the flank stability of the Hawaiian Islands. The testing showed that very weak rock exists in the hyaloclastite abundant zones in the lower 2-km of the core with strength dependent on the degree of consolidation and type of alteration. Walton and Schiffman identified three zones of alteration, an upper incipient alteration zone (1080-1335m), a smectitic zone (1405-1573m) and a lower palagonitic zone from about 1573 m to the base of the core. These three zones were sampled and tested together with pillow lava horizons for comparison. Traditional cylindrical core was not available as a consequence of the entire core having been split lengthwise for archival purposes. Hence, point load strength testing was utilized which provides the unconfined compressive strength on irregular shaped samples. The lowest unconfined strengths were recorded from incipient alteration zones with a mean value of 9.5 MPa. Smectitic alteration zones yielded mean values of 16.4 MPa, with the highest measured alteration strengths from the palagonite zones with a mean value of 32.1 MPa. As anticipated, the highest strengths were from essentially unaltered lavas with a mean value of 173 MPa. Strength variations of between one to two orders of magnitude were identified in comparing the submarine hyaloclastite with the intercalated submarine lavas. The weakest zones within the hyaloclastites may provide horizons for assisting flank collapse by serving as potential thrust zones and landslide surfaces.

  4. Hot metamorphic core complex in a cold foreland

    NASA Astrophysics Data System (ADS)

    Franke, Wolfgang; Doublier, Michael Patrick; Klama, Kai; Potel, Sébastien; Wemmer, Klaus

    2011-06-01

    The Montagne Noire forms the southernmost part of the French Massif Central. Carboniferous flysch sediments and very low-grade metamorphic imprint testify to a very external position in the orogen. Sedimentation of synorogenic clastic sediments continued up to the Viséan/Namurian boundary (≤320 Ma). Subsequently, the Palaeozoic sedimentary pile underwent recumbent folding and grossly southward thrusting. An extensional window exposes a hot core of Carboniferous HT/LP gneisses, migmatites and granites (Zone Axiale), which was uplifted from under the nappe pile. After the emplacement of the nappes on the Zone Axiale (Variscan D1), all structural levels shared the same tectonic evolution: D2 (extension and exhumation), D3 (refolding) and post-D3 dextral transtension. HT/LP-metamorphism in the crystalline rocks probably started before and continued after the emplacement of the nappes. Peak metamorphic temperatures were attained during a post-nappe thermal increment (M2). M2 occurred during ENE-directed bilateral extension, which exhumed the Zone Axiale and its frame as a ductile horst structure, flanked to the ENE by a Stephanian intra-montane basin. Map patterns and mesoscopic structures reveal that extension in ENE occurred simultaneously with NNW-oriented shortening. Combination of these D2 effects defines a bulk prolate strain in a "pinched pull-apart" setting. Ductile D2 deformation during M2 dominates the structural record. In wide parts of the nappes on the southern flank of the Zone Axiale, D1 is only represented by the inverted position of bedding (overturned limbs of recumbent D1 folds) and by refolded D1 folds. U-Pb monazite and zircon ages and K-Ar muscovite ages are in accord with Ar-Ar data from the literature. HT/LP metamorphism and granitoid intrusion commenced already at ≥330 Ma and continued until 297 Ma, and probably in a separate pulse in post-Stephanian time. Metamorphic ages older than c. 300 Ma are not compatible with the classical model of

  5. Isomer and glycomer complexities of core GlcNAcs in Caenorhabditis elegans.

    PubMed

    Hanneman, Andrew J; Rosa, José César; Ashline, David; Reinhold, Vernon N

    2006-09-01

    Analysis of protein glycosylation within the nematode Caenorhabditis elegans has revealed an abundant and unreported set of core chitobiose modifications (CCMs) to N-linked glycans. With hydrazine release, an array of glycomers and isobars were detected with hexose extensions on the 3- and 3,6-positions of the penultimate and reducing terminus, respectively. A full complement of structures includes a range of glycomers possessing a Galbeta(1-4)Fuc disaccharide at the 3- and 6-positions of the protein-linked GlcNAc. Importantly, enzymatic (PNGase F/A) release failed to liberate many of these extended structures from reduced and alkylated peptides and, as a consequence, such profiles were markedly deficient in a representation of the worm glycome. Moreover, the 3-linked Galbeta(1-4)Fuc moiety was notably resistant to a range of commercial galactosidases. For identification, the fragments were spectrum-matched with synthetic products and library standards using sequential mass spectrometry (MS(n)). A disaccharide observed at the 3-position of penultimate GlcNAc, indicating a Hex-Fuc branch on some structures, was not further characterized because of low ion abundance in MS(n). Additionally, a Hex-Hex-Fuc trisaccharide on the 6-position of proximal GlcNAc was also distinguished on select glycomers. Similar branch extensions on 6-linked core fucosyl residues have recently been reported among other invertebrates. Natural methylation and numerous isobars complement the glycome, which totals well over 100 individual structures. Complex glycans were detected at lower abundance, indicating glucosaminyltransferase-I (GnT-I) and GnT-II activity. A range of phosphorylcholine (PC)-substituted complex glycans were also confirmed following a signature two-stage loss of PC during MS(n) analysis, although the precursor ion was not observed in the mass profiles. In a similar manner, numerous other minor glycans may be present but unobserved in hydrazine-release profiles dominated by

  6. A chromospheric dark-cored fibril in Ca II IR spectra

    NASA Astrophysics Data System (ADS)

    Beck, C.; Tritschler, A.; Wöger, F.

    2010-06-01

    We investigate the thermodynamical and magnetic properties of a ``dark-cored" fibril seen in the chromospheric Ca II IR line at 854.2 nm to determine the physical process behind its appearance. We analyse a time series of spectropolarimetric observations obtained in the Ca II IR line at 854.2 nm and the photospheric Fe I line at 630.25 nm. We simultaneously invert the spectra in both wavelength ranges with the SIR code to obtain the temperature and velocity stratification with height in the solar atmosphere and the magnetic field properties in the photosphere. The structure can be clearly traced in the line-of-sight (LOS) velocity and the temperature maps. It connects from a small pore with kG fields to a region with lower field strength. The flow velocity and the temperature indicate that the height of the structure increases with increasing distance from the inner footpoint. The Stokes V signal of 854.2 nm shows a Doppler-shifted polarization signal with the same displacement as in the intensity profile, indicating that the supersonic flow seen in the LOS velocity is located within magnetized plasma. We conclude that the chromospheric dark-cored fibril traces a siphon flow along magnetic field lines, driven by the gas pressure difference caused by the higher magnetic field strength at the inner footpoint. We suggest that fast flows guided by the magnetic field lead to the appearance of ``dark-cored" fibrils in intensity images. Although the observations included the determination of the polarization signal in the chromospheric Ca II IR line, the signal could not be analysed quantitatively due to the low S/N. Chromospheric polarimetry will thus require telescopes of larger aperture able to collect a sufficient number of photons for a reliable determination of polarization in deep and only weakly polarized spectral lines.

  7. Inhibition of Mitochondrial Complex II by the Anticancer Agent Lonidamine*

    PubMed Central

    Guo, Lili; Shestov, Alexander A.; Worth, Andrew J.; Nath, Kavindra; Nelson, David S.; Leeper, Dennis B.; Glickson, Jerry D.; Blair, Ian A.

    2016-01-01

    The antitumor agent lonidamine (LND; 1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid) is known to interfere with energy-yielding processes in cancer cells. However, the effect of LND on central energy metabolism has never been fully characterized. In this study, we report that a significant amount of succinate is accumulated in LND-treated cells. LND inhibits the formation of fumarate and malate and suppresses succinate-induced respiration of isolated mitochondria. Utilizing biochemical assays, we determined that LND inhibits the succinate-ubiquinone reductase activity of respiratory complex II without fully blocking succinate dehydrogenase activity. LND also induces cellular reactive oxygen species through complex II, which reduced the viability of the DB-1 melanoma cell line. The ability of LND to promote cell death was potentiated by its suppression of the pentose phosphate pathway, which resulted in inhibition of NADPH and glutathione generation. Using stable isotope tracers in combination with isotopologue analysis, we showed that LND increased glutaminolysis but decreased reductive carboxylation of glutamine-derived α-ketoglutarate. Our findings on the previously uncharacterized effects of LND may provide potential combinational therapeutic approaches for targeting cancer metabolism. PMID:26521302

  8. Cu(II) complex formation with xylitol in alkaline solutions.

    PubMed

    Norkus, Eugenijus; Vaiciūniene, Jūrate; Vuorinen, Tapani; Gaidamauskas, Ernestas; Reklaitis, Jonas; Jääskeläinen, Anna-Stiina; Crans, Debbie C

    2004-02-25

    The formation of four Cu(II)-xylitol complexes was observed in aqueous alkaline solutions (11.0< or =pH< or =14.0, I=1.0, 20 degrees C) by means of direct current polarography and VIS spectrophotometry. Mononuclear hydroxy complexes, CuXyl(OH)- (log beta=17.7 +/- 0.5), CuXyl(OH)2(2-) (log beta=20.2 +/- 0.3) and CuXyl2(OH)2(4-) (log beta=22.4 +/- 0.3), are formed at high ligand-to-metal ratios (L:M> or =10), whereas dinuclear complex Cu2Xyl (log beta=29.2 +/- 0.3) is the predominant species at low ligand-to-metal ratio (L:M=0.5). Diffusion coefficients and molar absorptivities of the complex species were determined. pH variable 13C NMR suggested that pKa values of xylitol are rather similar and equal to 13.8 +/- 0.2, 13.9 +/- 0.1 and 13.9 +/- 0.2 for OH-groups adjacent to (C-1,C-5), (C-3) and (C-2,C-4) carbon atoms, respectively.

  9. Platinum(II)-Acyclovir Complexes: Synthesis, Antiviral and Antitumour Activity

    PubMed Central

    Coluccia, M.; Boccarelli, A.; Cermelli, C.; Portolani, M.; Natile, G.

    1995-01-01

    A platinum(II) complex with the antiviral drug acyclovir was synthesized and its antiviral and anticancer properties were investigated in comparison to those of acyclovir and cisplatin. The platinum-acyclovir complex maintained the antiviral activity of the parent drug acyclovir, though showing a minor efficacy on a molar basis (ID50  =   7.85 and 1.02 μΜ for platinum-acyclovir and cisplatin, respectively). As anticancer agent, the platinum-acyclovir complex was markedly less potent than cisplatin on a mole-equivalent basis, but it was as effective as cisplatin when equitoxic dosages were administered in vivo to P388 leukaemia-bearing mice (%T/C = 209 and 211 for platinum-acyclovir and cisplatin, respectively). The platinum-acyclovir complex was also active against a cisplatin-resistant subline of the P388 leukaemia (%T/C = 140), thus suggesting a different mechanism of action. The DNA interaction properties (sequence specificity and interstrand cross-linking ability) of platinum-acyclovir were also investigated in comparison to those of cisplatin and [Pt(dien)Cl]+, an antitumour-inactive platinum-triamine compound. The results of this study point to a potential new drug endowed, at the same time, with antiviral and anticancer activity and characterized by DNA interaction properties different from those of cisplatin. PMID:18472776

  10. Widespread Use of TATA Elements in the Core Promoters for RNA Polymerases III, II, and I in Fission Yeast

    PubMed Central

    Hamada, Mitsuhiro; Huang, Ying; Lowe, Todd M.; Maraia, Richard J.

    2001-01-01

    In addition to directing transcription initiation, core promoters integrate input from distal regulatory elements. Except for rare exceptions, it has been generally found that eukaryotic tRNA and rRNA genes do not contain TATA promoter elements and instead use protein-protein interactions to bring the TATA-binding protein (TBP), to the core promoter. Genomewide analysis revealed TATA elements in the core promoters of tRNA and 5S rRNA (Pol III), U1 to U5 snRNA (Pol II), and 37S rRNA (Pol I) genes in Schizosaccharomyces pombe. Using tRNA-dependent suppression and other in vivo assays, as well as in vitro transcription, we demonstrated an obligatory requirement for upstream TATA elements for tRNA and 5S rRNA expression in S. pombe. The Pol III initiation factor Brf is found in complexes with TFIIIC and Pol III in S. pombe, while TBP is not, consistent with independent recruitment of TBP by TATA. Template commitment assays are consistent with this and confirm that the mechanisms of transcription complex assembly and initiation by Pol III in S. pombe differ substantially from those in other model organisms. The results were extended to large-rRNA synthesis, as mutation of the TATA element in the Pol I promoter also abolishes rRNA expression in fission yeast. A survey of other organisms' genomes reveals that a substantial number of eukaryotes may use widespread TATAs for transcription. These results indicate the presence of TATA-unified transcription systems in contemporary eukaryotes and provide insight into the residual need for TBP by all three Pols in other eukaryotes despite a lack of TATA elements in their promoters. PMID:11564871

  11. Isolation and purification of CP43 and CP47 photosystem II proximal antenna complexes from plants.

    PubMed

    Picorel, Rafael; Alfonso, Miguel; Seibert, Michael

    2011-01-01

    A method to isolate and purify CP43 and CP47 pigment-protein complexes from Photosystem (PS) II of higher plants is presented. The method has been developed in spinach, but it may also be valid for other plant species, since there is high PSII core complex homology in all plants. Core complex, obtained from highly enriched PSII membrane fragments (the extrinsic proteins were previously removed by Tris treatment), is used as starting material. The core complex is first treated with the chaotropic agent, LiClO4, and the nonionic detergent, n-dodecyl β-D-maltoside. After dialysis against buffer lacking detergent or chaotropic agent, the solubilized material is separated by anion-exchange chromatography using a TSK Toyopearl DEAE 650s column. CP43 complex does not bind to the column under these conditions and elutes along with free pigments and few other contaminants. When the eluate becomes colorless, the column is subjected to a 0-170-mM LiClO4 linear gradient. The main pigment elution band corresponds to the CP47 complex with some contaminants. To obtain pure preparations of CP43 and CP47 complexes, other chromatographic steps were developed. The CP43 material is passed through a S-Sepharose cation-exchange column at room temperature and then through a Q-Sepharose anion-exchange column. After dialysis, the solution is passed through a new Q-Sepharose anion-exchange column at a different pH. The bound material is eluted with a 10-70-mM MgSO4 linear gradient, and the fractions with a prominent peak at 670 nm and a clear shoulder at 683 nm are combined. This constitutes the pure CP43 complex. The CP47 material from the first column is dialyzed, loaded onto a new TSK Toyopearl DEAE 650s column, and eluted with a 0-175-mM LiClO4 linear gradient. The fractions with a peak at 674.8 nm are combined and constitute the pure CP47 complex.

  12. Spectral, thermal and biological studies of Mn(II) and Cu(II) complexes with two thiosemicarbazide derivatives.

    PubMed

    Refat, Moamen S; El-Metwaly, Nashwa M

    2012-06-15

    Two derivatives of thiosemicarbazide were prepared. Their complexes were prepared using Mn(II) and Cu(II) salts. All the isolated complexes are characterized using the following spectra: IR, UV-Vis, Mass, (1)H NMR and X-ray diffraction. Magnetic measurements and thermal analysis are the other additive tools for complete investigation. Mononuclear and binuclear complexes are proposed based on elemental analysis mainly. The IR spectra offer the mode of coordination of each ligand with each metal ion. The electronic spectra and magnetic measurements are proposing the structural geometry of the investigated complexes. The octahedral geometry proposed for Mn(II) complexes but the square-planar for Cu(II) complexes. The (1)H NMR spectra were done for all organic compounds used in this study and displaying the most suitable tautomer of them. X-ray diffraction of H(2)L(1) and its complexes show their amorphous nature but H(2)L(2) ligand and its complexes show their nanocrystalline nature. The TG analysis was used to prove the presence of solvent molecules attached with the complexes as covalently or physically. Finally, the biological investigation was carried out for H(2)L(2) ligand and its complexes and displaying the inhibition activity of Cu(II) complex than the Mn(II) one.

  13. Spectral, thermal and biological studies of Mn(II) and Cu(II) complexes with two thiosemicarbazide derivatives

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; El-Metwaly, Nashwa M.

    Two derivatives of thiosemicarbazide were prepared. Their complexes were prepared using Mn(II) and Cu(II) salts. All the isolated complexes are characterized using the following spectra: IR, UV-Vis, Mass, 1H NMR and X-ray diffraction. Magnetic measurements and thermal analysis are the other additive tools for complete investigation. Mononuclear and binuclear complexes are proposed based on elemental analysis mainly. The IR spectra offer the mode of coordination of each ligand with each metal ion. The electronic spectra and magnetic measurements are proposing the structural geometry of the investigated complexes. The octahedral geometry proposed for Mn(II) complexes but the square-planar for Cu(II) complexes. The 1H NMR spectra were done for all organic compounds used in this study and displaying the most suitable tautomer of them. X-ray diffraction of H2L1 and its complexes show their amorphous nature but H2L2 ligand and its complexes show their nanocrystalline nature. The TG analysis was used to prove the presence of solvent molecules attached with the complexes as covalently or physically. Finally, the biological investigation was carried out for H2L2 ligand and its complexes and displaying the inhibition activity of Cu(II) complex than the Mn(II) one.

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

    PubMed

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

    2006-10-01

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

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

    PubMed

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

    2002-05-21

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

  16. The Silver Complexes of Porphyrins, Corroles, and Carbaporphyrins: Silver in the Oxidation States II and III

    ERIC Educational Resources Information Center

    Bruckner, Christian

    2004-01-01

    Studies in relation to the silver complexes of porphyrins, corroles and carbaporphyrins are presented especially with relation to silver in the oxidation states II and III. It is seen that the Ag(sub III) complex was electrochemically readily and reversibly reduced to the corresponding Ag(sub II) complex, thus indicating that the complex could be…

  17. An assessment of the Arctic Ocean in a suite of interannual CORE-II simulations. Part II: Liquid freshwater

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Ilicak, Mehmet; Gerdes, Rüdiger; Drange, Helge; Aksenov, Yevgeny; Bailey, David A.; Bentsen, Mats; Biastoch, Arne; Bozec, Alexandra; Böning, Claus; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Curry, Beth; Danabasoglu, Gokhan; Danilov, Sergey; Fernandez, Elodie; Fogli, Pier Giuseppe; Fujii, Yosuke; Griffies, Stephen M.; Iovino, Doroteaciro; Jahn, Alexandra; Jung, Thomas; Large, William G.; Lee, Craig; Lique, Camille; Lu, Jianhua; Masina, Simona; Nurser, A. J. George; Rabe, Benjamin; Roth, Christina; Salas y Mélia, David; Samuels, Bonita L.; Spence, Paul; Tsujino, Hiroyuki; Valcke, Sophie; Voldoire, Aurore; Wang, Xuezhu; Yeager, Steve G.

    2016-03-01

    The Arctic Ocean simulated in 14 global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE-II) is analyzed in this study. The focus is on the Arctic liquid freshwater (FW) sources and freshwater content (FWC). The models agree on the interannual variability of liquid FW transport at the gateways where the ocean volume transport determines the FW transport variability. The variation of liquid FWC is induced by both the surface FW flux (associated with sea ice production) and lateral liquid FW transport, which are in phase when averaged on decadal time scales. The liquid FWC shows an increase starting from the mid-1990s, caused by the reduction of both sea ice formation and liquid FW export, with the former being more significant in most of the models. The mean state of the FW budget is less consistently simulated than the temporal variability. The model ensemble means of liquid FW transport through the Arctic gateways compare well with observations. On average, the models have too high mean FWC, weaker upward trends of FWC in the recent decade than the observation, and low consistency in the temporal variation of FWC spatial distribution, which needs to be further explored for the purpose of model development.

  18. Discovery of protein complexes with core-attachment structures from Tandem Affinity Purification (TAP) data.

    PubMed

    Wu, Min; Li, Xiao-Li; Kwoh, Chee-Keong; Ng, See-Kiong; Wong, Limsoon

    2012-09-01

    Many cellular functions involve protein complexes that are formed by multiple interacting proteins. Tandem Affinity Purification (TAP) is a popular experimental method for detecting such multi-protein interactions. However, current computational methods that predict protein complexes from TAP data require converting the co-complex relationships in TAP data into binary interactions. The resulting pairwise protein-protein interaction (PPI) network is then mined for densely connected regions that are identified as putative protein complexes. Converting the TAP data into PPI data not only introduces errors but also loses useful information about the underlying multi-protein relationships that can be exploited to detect the internal organization (i.e., core-attachment structures) of protein complexes. In this article, we propose a method called CACHET that detects protein complexes with Core-AttaCHment structures directly from bipartitETAP data. CACHET models the TAP data as a bipartite graph in which the two vertex sets are the baits and the preys, respectively. The edges between the two vertex sets represent bait-prey relationships. CACHET first focuses on detecting high-quality protein-complex cores from the bipartite graph. To minimize the effects of false positive interactions, the bait-prey relationships are indexed with reliability scores. Only non-redundant, reliable bicliques computed from the TAP bipartite graph are regarded as protein-complex cores. CACHET constructs protein complexes by including attachment proteins into the cores. We applied CACHET on large-scale TAP datasets and found that CACHET outperformed existing methods in terms of prediction accuracy (i.e., F-measure and functional homogeneity of predicted complexes). In addition, the protein complexes predicted by CACHET are equipped with core-attachment structures that provide useful biological insights into the inherent functional organization of protein complexes. Our supplementary material can

  19. Photocatalytic degradation of bromothymol blue with Ruthenium(II) bipyridyl complex in aqueous basic solution

    NASA Astrophysics Data System (ADS)

    Fui, Mark Lee Wun; Hang, Ng Kim; Arifin, Khuzaimah; Minggu, Lorna Jeffery; Kassim, Mohammad Bin

    2016-11-01

    Ru(II) bipyridyl photocatalyst with the formula, [Ru(bpy)2(o-CH3-bzpypz)](PF6)2] (Ru01) and [Ru(bpy)2(o-Cl-bzpypz)](PF6)2] (Ru02), where bpy = 2,2'-bipyridyl, o-CH3-bzpypz = (3-(pyridin-2-yl)-1H-pyrazol-1-yl)(o-tolyl)methanone and o-Cl-bzpypz = (2-chlorophenyl)(3-(pyridin-2-yl)-1H-pyrazol-1-yl)methanone, has been successfully synthesized and characterized on the basis of C, H, N elemental analysis, IR, UV-Vis and NMR spectroscopy. Both Ru(II) complexes showed Infrared stretching frequencies at 1742-1736 cm-1 v(C=O), 1605 cm-1 v(C=N) and 842-837 cm-1 v(PF). Full geometry optimization of the complex structures were carried out using DFT method with B3LYP exchange-correlation functional and 6-31G (d,p) basis-set for H, C, N, O and Cl; and LAN2LDZ basis set as effective core potential for the ruthenium centre. The highest-occupied molecular orbital (HOMO) energy levels of Ru01 and Ru02 are -5.63 and -5.55 eV, respectively. The photocatalytic properties of the Ru(II) complexes were evaluated by studying the degradation of aqueous bromothymol blue (BTB) under light illumination. The mechanisms are presented and discussed to highlight the role of the ruthenium complex in the degradation process.

  20. Papain digestion of crude Trichoderma reesei cellulase: Purification and properties of cellobiohydrolase I and II core proteins

    SciTech Connect

    Woodward, J.; Brown, J.P.; Evans, B.R.; Affholter, K.A.

    1992-12-01

    Papain digestion of a crude Trichoderma reesei cellulose preparation followed by gel filtration on a Superdex column resulted in the separation of cellobiohydrolase (CBH) I and II core proteins (cp). They were further purified to apparent homogeneity by chromatofocusing. N-terminal protein sequencing of the CBH II cp preparation confirmed its identity. A comparison of the catalytic activity and cellulose-binding ability of these core proteins was made. The major differences between them were the findings that CBH II cp possessed a sixfold higher specific activity toward p-nitrophenylcellobioside than the native CBH II preparation and still bound to microcrystalline cellulose, unlike CBH I cp. Neither CBH I cp nor CBH II cp had activity toward carboxymethylcellulose, but both were able to hydrolyze barley b-glucan. These data suggest that removal of the cellulose-binding domain and hinge region from CBH I and II have different effects on their properties.

  1. Papain digestion of crude Trichoderma reesei cellulase: Purification and properties of cellobiohydrolase I and II core proteins

    SciTech Connect

    Woodward, J.; Brown, J.P.; Evans, B.R.; Affholter, K.A.

    1992-01-01

    Papain digestion of a crude Trichoderma reesei cellulose preparation followed by gel filtration on a Superdex column resulted in the separation of cellobiohydrolase (CBH) I and II core proteins (cp). They were further purified to apparent homogeneity by chromatofocusing. N-terminal protein sequencing of the CBH II cp preparation confirmed its identity. A comparison of the catalytic activity and cellulose-binding ability of these core proteins was made. The major differences between them were the findings that CBH II cp possessed a sixfold higher specific activity toward p-nitrophenylcellobioside than the native CBH II preparation and still bound to microcrystalline cellulose, unlike CBH I cp. Neither CBH I cp nor CBH II cp had activity toward carboxymethylcellulose, but both were able to hydrolyze barley b-glucan. These data suggest that removal of the cellulose-binding domain and hinge region from CBH I and II have different effects on their properties.

  2. The treatment of mixing in core helium burning models - II. Constraints from cluster star counts

    NASA Astrophysics Data System (ADS)

    Constantino, Thomas; Campbell, Simon W.; Lattanzio, John C.; van Duijneveldt, Adam

    2016-03-01

    The treatment of convective boundaries during core helium burning is a fundamental problem in stellar evolution calculations. In the first paper of this series, we showed that new asteroseismic observations of these stars imply they have either very large convective cores or semiconvection/partially mixed zones that trap g modes. We probe this mixing by inferring the relative lifetimes of asymptotic giant branch (AGB) and horizontal branch (HB) from R2, the observed ratio of these stars in recent HST photometry of 48 Galactic globular clusters. Our new determinations of R2 are more self-consistent than those of previous studies and our overall calculation of R2 = 0.117 ± 0.005 is the most statistically robust now available. We also establish that the luminosity difference between the HB and the AGB clump is Δ log {L}_HB^AGB = 0.455 ± 0.012. Our results accord with earlier findings that standard models predict a lower R2 than is observed. We demonstrate that the dominant sources of uncertainty in models are the prescription for mixing and the stochastic effects that can result from its numerical treatment. The luminosity probability density functions that we derive from observations feature a sharp peak near the AGB clump. This constitutes a strong new argument against core breathing pulses, which broaden the predicted width of the peak. We conclude that the two mixing schemes that can match the asteroseismology are capable of matching globular cluster observations, but only if (i) core breathing pulses are avoided in models with a semiconvection/partially mixed zone, or (ii) that models with large convective cores have a particular depth of mixing beneath the Schwarzschild boundary during subsequent early-AGB `gravonuclear' convection.

  3. Reaction of a copper(II)-nitrosyl complex with hydrogen peroxide: phenol ring nitration through a putative peroxynitrite intermediate.

    PubMed

    Kalita, Apurba; Deka, Ramesh C; Mondal, Biplab

    2013-10-07

    Copper(II) complex, 1, with the histidine-derived ligand L (L = methyl 2-(2-hydroxybenzylamino)-3-(1H-imidazol-5-yl)propanoate) has been synthesized and characterized. Single-crystal structure determination reveals a diphenolato-bridged dicopper(II) core in 1. Addition of (•)NO to an acetonitrile solution of 1 affords the corresponding mononuclear copper(II)-nitrosyl complex, 2. In the presence of H2O2, 2 results in formation of the corresponding copper(I)-peroxynitrite. Formation of peroxynitrite ((-)OONO) intermediate is evident from its characteristic phenol ring nitration reaction which resembles the tyrosine nitration in biological systems. Further, isolation of nitrate (NO3(-)) as the decomposition product from 2 at room temperature also supports the involvement of (-)OONO intermediate.

  4. Metal Zn(II), Cu(II), Ni (II) complexes of ursodeoxycholic acid as putative anticancer agents

    PubMed Central

    Dyakova, Lora; Culita, Daniela-Cristina; Marinescu, Gabriela; Alexandrov, Marin; Kalfin, Reni; Patron, Luminita; Alexandrova, Radostina

    2014-01-01

    The aim of the study was to evaluate the influence of metal [Zn(II), Cu(II), Ni(II)] complexes with ursodeoxycholic acid (UDCA) on the viability and proliferation of tumour and non-tumour cells. Cell lines established from retrovirus-transformed chicken hepatoma (LSCC-SF-Mc29) and rat sarcoma (LSR-SF-SR) as well as from human cancers of the breast (MCF-7), uterine cervix (HeLa), lung (A549) and liver (HepG2) were used as model systems. Non-tumour human embryo (Lep-3) cells were also included in some of the experiments. The investigations were carried out by the thiazolyl blue tetrazolium bromide (MTT) test, neutral red uptake cytotoxicity assay, crystal violet staining, double staining with acridine orange and propidium iodide and the colony-forming method. The results obtained revealed that: (1) UDCA and its metal complexes in the tested concentrations decreased (to a varying degree) the viability and proliferation of the treated cells in a time- and concentration-dependent manner; (2) chicken hepatoma (LSCC-SF-Mc29) cells were most sensitive to the cytotoxic and antiproliferative action of the compounds tested, followed by rat sarcoma (LSR-SF-SR) cells; (3) Cu‒UDCA and Ni‒UDCA were more effective against animal LSCC-SF-Mc29 and LSR-SF-SR cells, while Zn‒UDCA significantly decreased the viability and proliferation of human tumour cell lines; (4) applied independently, UDCA expressed lower cytotoxic/cytostatic activity as compared to metal complexes; and (5) the sensitivity of the non-tumour embryonic Lep-3 cells to the effects of UDCA and its metal complexes was comparable or even higher than those of the human tumour cells. PMID:26019542

  5. Structure of the acetophenone carboxylase core complex: prototype of a new class of ATP-dependent carboxylases/hydrolases

    PubMed Central

    Weidenweber, Sina; Schühle, Karola; Demmer, Ulrike; Warkentin, Eberhard; Ermler, Ulrich; Heider, Johann

    2017-01-01

    Degradation of the aromatic ketone acetophenone is initiated by its carboxylation to benzoylacetate catalyzed by acetophenone carboxylase (Apc) in a reaction dependent on the hydrolysis of two ATP to ADP and Pi. Apc is a large protein complex which dissociates during purification into a heterooctameric Apc(αα′βγ)2 core complex of 482 kDa and Apcε of 34 kDa. In this report, we present the X-ray structure of the Apc(αα′βγ)2 core complex from Aromatoleum aromaticum at ca. 3 Å resolution which reveals a unique modular architecture and serves as model of a new enzyme family. Apcβ contains a novel domain fold composed of two β-sheets in a barrel-like arrangement running into a bundle of eight short polyproline (type II)-like helical segments. Apcα and Apcα′ possess ATP binding modules of the ASKHA superfamily integrated into their multidomain structures and presumably operate as ATP-dependent kinases for acetophenone and bicarbonate, respectively. Mechanistic aspects of the novel carboxylation reaction requiring massive structural rearrangements are discussed and criteria for specifically annotating the family members Apc, acetone carboxylase and hydantoinase are defined. PMID:28054554

  6. Identification of FAAP24, a Fanconi anemia core complex protein that interacts with FANCM.

    PubMed

    Ciccia, Alberto; Ling, Chen; Coulthard, Rachel; Yan, Zhijiang; Xue, Yutong; Meetei, Amom Ruhikanta; Laghmani, El Houari; Joenje, Hans; McDonald, Neil; de Winter, Johan P; Wang, Weidong; West, Stephen C

    2007-02-09

    The Fanconi anemia (FA) core complex plays a crucial role in a DNA damage response network with BRCA1 and BRCA2. How this complex interacts with damaged DNA is unknown, as only the FA core protein FANCM (the homolog of an archaeal helicase/nuclease known as HEF) exhibits DNA binding activity. Here, we describe the identification of FAAP24, a protein that targets FANCM to structures that mimic intermediates formed during the replication/repair of damaged DNA. FAAP24 shares homology with the XPF family of flap/fork endonucleases, associates with the C-terminal region of FANCM, and is a component of the FA core complex. FAAP24 is required for normal levels of FANCD2 monoubiquitylation following DNA damage. Depletion of FAAP24 by siRNA results in cellular hypersensitivity to DNA crosslinking agents and chromosomal instability. Our data indicate that the FANCM/FAAP24 complex may play a key role in recruitment of the FA core complex to damaged DNA.

  7. Isolation of photosystem II-enriched membranes and the oxygen-evolving complex subunit proteins from higher plants.

    PubMed

    Yamamoto, Yasusi; Leng, Jing; Shen, Jian-Ren

    2011-01-01

    We describe methods to isolate highly active oxygen-evolving photosystem II (PSII) membranes and core complexes from higher plants, and to purify subunits of the oxygen-evolving complex (OEC). The membrane samples used as the material for various in vitro studies of PSII are prepared by solubilizing thylakoid membranes with the nonionic detergent Triton X-100, and the core complexes are prepared by further solubilization of the PSII membranes with n-dodecyl-β-D-maltoside (β-DDM). The OEC subunit proteins are dissociated from the PSII-enriched membranes by alkaline or salt treatment, and are then purified by ion-exchange chromatography using an automated high performance liquid chromatography system.

  8. Copper(II) and nickel(II) complexes of benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone: Synthesis, characterization and biological activity

    NASA Astrophysics Data System (ADS)

    Prathima, B.; Subba Rao, Y.; Adinarayana Reddy, S.; Reddy, Y. P.; Varada Reddy, A.

    2010-09-01

    Benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone ligand (L) has been synthesized from benzyloxybenzaldehyde and 4-phenyl-3-thiosemicarbazide. Complexes of this ligand with chlorides of Cu(II) and Ni(II) have been prepared. The structure of the ligand (L) is proposed based on elemental analysis, IR and 1H NMR spectra. Its complexes with Cu(II) and Ni(II) ions are characterized from the studies of electronic as well as EPR spectra. On the basis of electronic and EPR studies, rhombically distorted octahedral structure has been proposed for Cu(II) complex while the Ni(II) complex has been found to acquire an octahedral structure. The ligand and their metal complexes have been tested in vitro for their biological effects. Their antibacterial activities against Gram-negative bacteria ( Escherichia coli and Klebsiella pneumoniae) and Gram-positive bacteria ( Staphylococcus aureus and Bacillus subtilis) have been investigated. The prepared metal complexes exhibit higher antibacterial activities than the parent ligand. The in vitro antioxidant activity of free ligand and its metal(II) complexes have also been investigated and the results however reveal that the ligand exhibits greater antioxidant activity than its complexes.

  9. Copper(II) and nickel(II) complexes of benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone: Synthesis, characterization and biological activity.

    PubMed

    Prathima, B; Subba Rao, Y; Adinarayana Reddy, S; Reddy, Y P; Varada Reddy, A

    2010-09-15

    Benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone ligand (L) has been synthesized from benzyloxybenzaldehyde and 4-phenyl-3-thiosemicarbazide. Complexes of this ligand with chlorides of Cu(II) and Ni(II) have been prepared. The structure of the ligand (L) is proposed based on elemental analysis, IR and (1)H NMR spectra. Its complexes with Cu(II) and Ni(II) ions are characterized from the studies of electronic as well as EPR spectra. On the basis of electronic and EPR studies, rhombically distorted octahedral structure has been proposed for Cu(II) complex while the Ni(II) complex has been found to acquire an octahedral structure. The ligand and their metal complexes have been tested in vitro for their biological effects. Their antibacterial activities against Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) have been investigated. The prepared metal complexes exhibit higher antibacterial activities than the parent ligand. The in vitro antioxidant activity of free ligand and its metal(II) complexes have also been investigated and the results however reveal that the ligand exhibits greater antioxidant activity than its complexes.

  10. Phenoxide bridged tetranuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes: Electrochemical, magnetic and antimicrobial studies

    NASA Astrophysics Data System (ADS)

    Kamath, Anupama; Kulkarni, Naveen V.; Netalkar, Priya P.; Revankar, Vidyanand K.

    2011-09-01

    Phenoxide bridged later first row transition metal(II) complexes have been prepared by the interaction of later 3d transition metal(II) chlorides with tetranucleating compartmental Schiff base ligand system derived from 2,6-diformyl-4-methylphenol, p-phenylenediamine and 2-hydrazinobenzothiazole. Ligand and complexes were characterized by analytical, spectral (IR, UV-visible, ESR, FAB-mass and fluorescence), magnetic and thermal studies. All complexes are found to have octahedral geometry. The mutual influence of metal centres in terms of cooperative effect on the electronic, magnetic, electrochemical and structural properties was investigated. The Schiff base and its complexes have been screened for their antibacterial (against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa) and antifungal activities (against Aspergillus niger, and Candida albicans).

  11. Phenoxide bridged tetranuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes: electrochemical, magnetic and antimicrobial studies.

    PubMed

    Kamath, Anupama; Kulkarni, Naveen V; Netalkar, Priya P; Revankar, Vidyanand K

    2011-09-01

    Phenoxide bridged later first row transition metal(II) complexes have been prepared by the interaction of later 3d transition metal(II) chlorides with tetranucleating compartmental Schiff base ligand system derived from 2,6-diformyl-4-methylphenol, p-phenylenediamine and 2-hydrazinobenzothiazole. Ligand and complexes were characterized by analytical, spectral (IR, UV-visible, ESR, FAB-mass and fluorescence), magnetic and thermal studies. All complexes are found to have octahedral geometry. The mutual influence of metal centres in terms of cooperative effect on the electronic, magnetic, electrochemical and structural properties was investigated. The Schiff base and its complexes have been screened for their antibacterial (against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa) and antifungal activities (against Aspergillus niger, and Candida albicans).

  12. Construction of a Ca II Core-to-Wing Ratio Image

    NASA Astrophysics Data System (ADS)

    Roberts, H.

    2015-12-01

    To understand Earth's climate, we must first understand the Sun. However, there are still significant uncertainties associated with both the fundamental mechanisms of solar variability and how they enter into the Earth's climate system. An important method to study the causes of solar variability can be found through the analysis of solar images. The Precision Solar Photometric Telescope (PSPT) located at the Mauna Loa Solar Observatory (MLSO) acquires images of the Sun in three different photometric bands to monitor the evolution of solar surface features that change over the course of a solar cycle. These images provide a complete knowledge about the Sun by targeting different layers of the solar atmosphere. Though raw images are meaningful and important, precision image processing is required to remove instrumental artifacts and false features that may appear in these images prior to usage for scientific purposes. A scientific application of the high precision solar images is investigated by analyzing a set of narrow band of Calcium II K core and wing images. The Core and Wing images are processed to remove the influence of the center-to-limb variation; the resultant core-to-wing ratio image enhances the appearance of network structures on the entire solar disk along with the more obvious facula and plage brightening associated with the passage of active regions.

  13. Modulating the Anticancer Activity of Ruthenium(II)-Arene Complexes.

    PubMed

    Clavel, Catherine M; Păunescu, Emilia; Nowak-Sliwinska, Patrycja; Griffioen, Arjan W; Scopelliti, Rosario; Dyson, Paul J

    2015-04-23

    Following the identification of [Ru(η(6)-p-cymene)Cl2(1H,1H,2H,2H-perfluorodecyl-3-(pyridin-3-yl)propanoate)], a ruthenium(II)-arene complex with a perfluoroalkyl-modified ligand that displays remarkable in vitro cancer cell selectivity, a series of structurally related compounds were designed. In the new derivatives, the p-cymene ring and/or the chloride ligands are substituted by other ligands to modulate the steric bulk or aquation kinetics. The new compounds were evaluated in both in vitro (cytotoxicity and migration assays) and in vivo (chicken chorioallantoic membrane) models and were found to exhibit potent antivascular effects.

  14. Anticancer Organometallic Osmium(II)-p-cymene Complexes.

    PubMed

    Păunescu, Emilia; Nowak-Sliwinska, Patrycja; Clavel, Catherine M; Scopelliti, Rosario; Griffioen, Arjan W; Dyson, Paul J

    2015-09-01

    Osmium compounds are attracting increasing attention as potential anticancer drugs. In this context, a series of bifunctional organometallic osmium(II)-p-cymene complexes functionalized with alkyl or perfluoroalkyl groups were prepared and screened for their antiproliferative activity. Three compounds from the series display selectivity toward cancer cells, with moderate cytotoxicity observed against human ovarian carcinoma (A2780) cells, whereas no cytotoxicity was observed on non-cancerous human embryonic kidney (HEK-293) cells and human endothelial (ECRF24) cells. Two of these three cancer-cell-selective compounds induce cell death largely via apoptosis and were also found to disrupt vascularization in the chicken embryo chorioallantoic membrane (CAM) model. Based on these promising properties, these compounds have potential clinical applications.

  15. Synthesis, Characterization, and Antibacterial Studies of Pd(II) and Pt(II) Complexes of Some Diaminopyrimidine Derivatives

    PubMed Central

    Ajibade, Peter A.; Idemudia, Omoruyi G.

    2013-01-01

    Pd(II) and Pt(II) complexes of trimethoprim and pyrimethamine were synthesized and characterized by elemental analysis, UV-Vis, FTIR, and NMR spectroscopy. The complexes are formulated as four coordinate square planar species containing two molecules of the drugs and two chloride or thiocyanate ions. The coordination of the metal ions to the pyrimidine nitrogen atom of the drugs was confirmed by spectroscopic analyses. The complexes were screened for their antibacterial activities against eight bacterial isolates. They showed varied activities with the active metal complexes showing more enhanced inhibition than either trimethoprim or pyrimethamine. The Pd(II) complexes of pyrimethamine showed unique inhibitory activities against P. aeruginosa and B. pumilus, and none of the other complexes or the drugs showed any activity against these bacteria isolates. The MIC and MBC determinations revealed that these Pd(II) complexes are the most active. Structure activity relationship showed that Pt(II) complexes containing chloride ions are more active, while for Pd(II) complexes containing thiocyanate ions showed more enhanced activity than those containing chloride ions. PMID:23573071

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

    PubMed

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

    2009-04-01

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

  17. Characterization of Folding Cores in the Cyclophilin A-Cyclosporin A Complex

    PubMed Central

    Heal, Jack W.; Wells, Stephen A.; Blindauer, Claudia A.; Freedman, Robert B.; Römer, Rudolf A.

    2015-01-01

    Determining the folding core of a protein yields information about its folding process and dynamics. The experimental procedures for identifying the amino acids that make up the folding core include hydrogen-deuterium exchange and Φ-value analysis and can be expensive and time consuming. Because of this, there is a desire to improve upon existing methods for determining protein folding cores theoretically. We have obtained HDX data for the complex of cyclophilin A with the immunosuppressant cyclosporin A. We compare these data, as well as literature values for uncomplexed cyclophilin A, to theoretical predictions using a combination of rigidity analysis and coarse-grained simulations of protein motion. We find that in this case, the most specific prediction of folding cores comes from a combined approach that models the rigidity of the protein using the first software suite and the dynamics of the protein using the froda tool. PMID:25863065

  18. Electrostatic effects on proton coupled electron transfer in oxomanganese complexes inspired by the oxygen-evolving complex of photosystem II.

    PubMed

    Amin, Muhamed; Vogt, Leslie; Vassiliev, Serguei; Rivalta, Ivan; Sultan, Mohammad M; Bruce, Doug; Brudvig, Gary W; Batista, Victor S; Gunner, M R

    2013-05-23

    The influence of electrostatic interactions on the free energy of proton coupled electron transfer in biomimetic oxomanganese complexes inspired by the oxygen-evolving complex (OEC) of photosystem II (PSII) are investigated. The reported study introduces an enhanced multiconformer continuum electrostatics (MCCE) model, parametrized at the density functional theory (DFT) level with a classical valence model for the oxomanganese core. The calculated pKa's and oxidation midpoint potentials (E(m)'s) match experimental values for eight complexes, indicating that purely electrostatic contributions account for most of the observed couplings between deprotonation and oxidation state transitions. We focus on pKa's of terminal water ligands in [Mn(II/III)(H2O)6](2+/3+) (1), [Mn(III)(P)(H2O)2](3-) (2, P = 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphyrinato), [Mn2(IV,IV)(μ-O)2(terpy)2(H2O)2](4+) (3, terpy = 2,2':6',2″-terpyridine), and [Mn3(IV,IV,IV)(μ-O)4(phen)4(H2O)2](4+) (4, phen = 1,10-phenanthroline) and the pKa's of μ-oxo bridges and Mn E(m)'s in [Mn2(μ-O)2(bpy)4] (5, bpy = 2,2'-bipyridyl), [Mn2(μ-O)2(salpn)2] (6, salpn = N,N'-bis(salicylidene)-1,3-propanediamine), [Mn2(μ-O)2(3,5-di(Cl)-salpn)2] (7), and [Mn2(μ-O)2(3,5-di(NO2)-salpn)2] (8). The analysis of complexes 6-8 highlights the strong coupling between electron and proton transfers, with any Mn oxidation lowering the pKa of an oxo bridge by 10.5 ± 0.9 pH units. The model also accounts for changes in the E(m)'s by ligand substituents, such as found in complexes 6-8, due to the electron withdrawing Cl (7) and NO2 (8). The reported study provides the foundation for analysis of electrostatic effects in other oxomanganese complexes and metalloenzymes, where proton coupled electron transfer plays a fundamental role in redox-leveling mechanisms.

  19. Synthesis, characterization, DFT and biological studies of isatinpicolinohydrazone and its Zn(II), Cd(II) and Hg(II) complexes.

    PubMed

    El-Gammal, O A; Rakha, T H; Metwally, H M; Abu El-Reash, G M

    2014-06-05

    Isatinpicolinohydrazone (H2IPH) and its Zn(II), Cd(II) and Hg(II) complexes have been synthesized and investigated using physicochemical techniques viz. IR, (1)H NMR, (13)C NMR, UV-Vis spectrometric methods and magnetic moment measurements. The investigation revealed that H2IPH acts as binegative tetradentate in Zn(II), neutral tridentate in Cd(II) and as neutral bidentate towards Hg(II) complex. Octahedral geometry is proposed for all complexes. The bond length, bond angle, chemical reactivity, energy components (kcal/mol), binding energy (kcal/mol) and dipole moment (Debyes) for all the title compounds were evaluated by DFT and also MEP for the ligand is shown. Theoretical infrared intensities of H2IPH and also the theoretical electronic spectra of the ligand and its complexes were calculated. The thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. The in vitro antibacterial studies of the complexes proved them as growth inhibiting agents. The DDPH antioxidant of the compounds have been screened. Antitumor activity, carried out in vitro on human mammary gland (breast) MCF7, have shown that Hg(II) complex exhibited potent activity followed by Zn(II), Cd(II) complexes and the ligand.

  20. Synthesis, characterization, DFT and biological studies of isatinpicolinohydrazone and its Zn(II), Cd(II) and Hg(II) complexes

    NASA Astrophysics Data System (ADS)

    El-Gammal, O. A.; Rakha, T. H.; Metwally, H. M.; Abu El-Reash, G. M.

    2014-06-01

    Isatinpicolinohydrazone (H2IPH) and its Zn(II), Cd(II) and Hg(II) complexes have been synthesized and investigated using physicochemical techniques viz. IR, 1H NMR, 13C NMR, UV-Vis spectrometric methods and magnetic moment measurements. The investigation revealed that H2IPH acts as binegative tetradentate in Zn(II), neutral tridentate in Cd(II) and as neutral bidentate towards Hg(II) complex. Octahedral geometry is proposed for all complexes. The bond length, bond angle, chemical reactivity, energy components (kcal/mol), binding energy (kcal/mol) and dipole moment (Debyes) for all the title compounds were evaluated by DFT and also MEP for the ligand is shown. Theoretical infrared intensities of H2IPH and also the theoretical electronic spectra of the ligand and its complexes were calculated. The thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. The in vitro antibacterial studies of the complexes proved them as growth inhibiting agents. The DDPH antioxidant of the compounds have been screened. Antitumor activity, carried out in vitro on human mammary gland (breast) MCF7, have shown that Hg(II) complex exhibited potent activity followed by Zn(II), Cd(II) complexes and the ligand.

  1. Core Self-Evaluations as Causes of Satisfaction: The Mediating Role of Seeking Task Complexity

    ERIC Educational Resources Information Center

    Srivastava, Abhishek; Locke, Edwin A.; Judge, Timothy A.; Adams, John W.

    2010-01-01

    This study examined the mediating role of task complexity in the relationship between core self-evaluations (CSE) and satisfaction. In Study 1, eighty three undergraduate business students worked on a strategic decision-making simulation. The simulated environment enabled us to verify the temporal sequence of variables, use an objective measure of…

  2. ETD QA CORE TEAM: AN ELOQUENT SOLUTION TO A COMPLEX PROBLEM

    EPA Science Inventory

    ETD QA CORE TEAM: AN ELOQUENT SOLUTION TO A COMPLEX PROBLEMThomas J. Hughes, QA and Records Manager, Experimental Toxicology Division (ETD), National Health and Environmental Effects Research Laboratory (NHEERL), ORD, U.S. EPA, RTP, NC 27709

    ETD is the largest health divis...

  3. Complex decay patterns in atomic core photoionization disentangled by ion-recoil measurements

    SciTech Connect

    Guillemin, Renaud; Bomme, Cedric; Marin, Thierry; Journel, Loic; Marchenko, Tatiana; Kushawaha, Rajesh K.; Piancastelli, Maria Novella; Simon, Marc; Trcera, Nicolas

    2011-12-15

    Following core 1s ionization and resonant excitation of argon atoms, we measure the recoil energy of the ions due to momentum conservation during the emission of Auger electrons. We show that such ion momentum spectroscopy can be used to disentangle to some degree complex decay patterns, involving both radiative and nonradiative decays.

  4. Synthesis and characterization of Co(II), Ni(II), Cu(II) and Zn(II) complexes of tridentate Schiff base derived from vanillin and DL-α-aminobutyric acid

    NASA Astrophysics Data System (ADS)

    Nair, M. Sivasankaran; Joseyphus, R. Selwin

    2008-09-01

    Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from vanillin and DL-α-aminobutyric acid were synthesized and characterized by elemental analysis, IR, electronic spectra, conductance measurements, magnetic measurements, powder XRD and biological activity. The analytical data show the composition of the metal complex to be [ML(H 2O)], where L is the Schiff base ligand. The conductance data indicate that all the complexes are non-electrolytes. IR results demonstrate the tridentate binding of the Schiff base ligand involving azomethine nitrogen, phenolic oxygen and carboxylato oxygen atoms. The IR data also indicate the coordination of a water molecule with the metal ion in the complex. The electronic spectral measurements show that Co(II) and Ni(II) complexes have tetrahedral geometry, while Cu(II) complex has square planar geometry. The powder XRD studies indicate that Co(II) and Cu(II) complexes are amorphous, whereas Ni(II) and Zn(II) complexes are crystalline in nature. Magnetic measurements show that Co(II), Ni(II) and Cu(II) complexes have paramagnetic behaviour. Antibacterial results indicated that the metal complexes are more active than the ligand.

  5. Faulting evidence of isostatic uplift in the Rincon Mountains metamorphic core complex: An image processing analysis

    NASA Astrophysics Data System (ADS)

    Rodriguez-Guerra, Edna Patricia

    This study focuses on the applications of remote sensing techniques and digital analysis to characterizing of tectonic features of the Rincon Mountains metamorphic core complex. Data included Landsat Thematic Mapper (TM) images, digital elevation models (DEM), and digital orthophoto quadrangle quads (DOQQ). The main findings in this study are two nearly orthogonal systems of structures that have never been reported in the Rincon Mountains. The first system, a penetrative faulting system of the footwall rocks, trends N10--30°W. Similar structures identified in other metamorphic core complexes. The second system trends N60--70°E, and has only been alluded indirectly in the literature of metamorphic core complexes. The structures pervade mylonites in Tanque Verde Mountain, Mica Mountain, and the Rincon Peak area. As measured on the imagery, spacing between the N10--30°W lineaments ranges from ˜0.5 to 2 km, and from 0.25 to 1 km for the N60--70°E system. Field inspection reveals that the N10--30°W trending system, are high-angle normal faults dipping mainly to the west. One of the main faults, named here the Cabeza de Vaca fault, has a polished, planar, striated and grooved surface with slickenlines indicating pure normal dip-slip movement (N10°W, 83°SW; slickensides rake 85°SW). The Cabeza de Vaca fault is the eastern boundary of a 2 km-wide graben, with displacement as great as 400 meters. The N10--30°W faults are syn- to post-mylonitic, high-angle normal faults that formed during isostatic uplift of the Rincon core complex during mid-Tertiary time. This interpretation is based on previous works, which report similar fault patterns in other metamorphic core complexes. Faults trending N20--30°W, shape the east flank of Mica Mountain. These faults, on the back dipping mylonitic zone, dip east and may represent late-stage antithetic shear zones. The Cabeza de Vaca fault and the back dipping antithetic faults accommodate as much as 65% of the extension due to

  6. Synthesis, characterization and in vitro anticancer activity of 18-membered octaazamacrocyclic complexes of Co(II), Ni(II), Cd(II) and Sn(II)

    NASA Astrophysics Data System (ADS)

    Kareem, Abdul; Zafar, Hina; Sherwani, Asif; Mohammad, Owais; Khan, Tahir Ali

    2014-10-01

    An effective series of 18 membered octaazamacrocyclic complexes of the type [MLX2], where X = Cl or NO3 have been synthesized by template condensation reaction of oxalyl dihydrazide with dibenzoylmethane and metal salt in 2:2:1 molar ratio. The formation of macrocyclic framework, stereochemistry and their overall geometry have been characterized by various physico-chemical studies viz., elemental analysis, electron spray ionization-mass spectrometry (ESI-MS), I.R, UV-Vis, 1H NMR, 13C NMR spectroscopy, X-ray diffraction (XRD) and TGA/DTA studies. These studies suggest formation of octahedral macrocyclic complexes of Co(II), Ni(II), Cd(II) and Sn(II). The molar conductance values suggest nonelectrolytic nature for all the complexes. Thermogravimatric analysis shows that all the complexes are stable up to 600 °C. All these complexes have been tested against different human cancer cell lines i.e. human hepatocellular carcinoma (Hep3B), human cervical carcinoma (HeLa), human breast adenocarcinoma (MCF7) and normal cells (PBMC). The newly synthesized 18-membered octaazamacrocyclic complexes during in vitro anticancer evaluation, displayed moderate to good cytotoxicity on liver (Hep3B), cervical (HeLa) and breast (MCF7) cancer cell lines, respectively. The most effective anticancer cadmium complex (C34H28N10CdO10) was found to be active with IC50 values, 2.44 ± 1.500, 3.55 ± 1.600 and 4.82 ± 1.400 in micro-molar on liver, cervical and breast cancer cell lines, respectively.

  7. Five coordinate M(II)-diphenolate [M = Zn(II), Ni(II), and Cu(II)] Schiff base complexes exhibiting metal- and ligand-based redox chemistry.

    PubMed

    Franks, Mark; Gadzhieva, Anastasia; Ghandhi, Laura; Murrell, David; Blake, Alexander J; Davies, E Stephen; Lewis, William; Moro, Fabrizio; McMaster, Jonathan; Schröder, Martin

    2013-01-18

    Five-coordinate Zn(II), Ni(II), and Cu(II) complexes containing pentadentate N(3)O(2) Schiff base ligands [1A](2-) and [1B](2-) have been synthesized and characterized. X-ray crystallographic studies reveal five coordinate structures in which each metal ion is bound by two imine N-donors, two phenolate O-donors, and a single amine N-donor. Electron paramagnetic resonance (EPR) spectroscopic studies suggest that the N(3)O(2) coordination spheres of [Cu(1A)] and [Cu(1B)] are retained in CH(2)Cl(2) solution and solid-state superconducting quantum interference device (SQUID) magnetometric studies confirm that [Ni(1A)] and [Ni(1B)] adopt high spin (S = 1) configurations. Each complex exhibits two reversible oxidation processes between +0.05 and +0.64 V vs [Fc](+)/[Fc]. The products of one- and two-electron oxidations have been studied by UV/vis spectroelectrochemistry and by EPR spectroscopy which confirm that each oxidation process for the Zn(II) and Cu(II) complexes is ligand-based with sequential formation of mono- and bis-phenoxyl radical species. In contrast, the one-electron oxidation of the Ni(II) complexes generates Ni(III) products. This assignment is supported by spectroelectrochemical and EPR spectroscopic studies, density functional theory (DFT) calculations, and the single crystal X-ray structure of [Ni(1A)][BF(4)] which contains Ni in a five-coordinate distorted trigonal bipyramidal geometry.

  8. Hydrophilic drug encapsulation in shell-core microcarriers by two stage polyelectrolyte complexation method.

    PubMed

    Dalmoro, Annalisa; Sitenkov, Alexander Y; Cascone, Sara; Lamberti, Gaetano; Barba, Anna Angela; Moustafine, Rouslan I

    2017-02-25

    In this study a protocol exploiting the combination of the ultrasonic atomization and the complexation between polyelectrolytes was developed to efficiently encapsulate a hydrophilic chemotherapeutic agent essentially used in the treatment of colon cancer, 5-fluorouracil, in enteric shell-core alginate-based microcarriers. The atomization assisted by ultrasound allowed to obtain small droplets by supplying low energy and avoiding drug degradation. In particular microcarriers were produced in a home-made apparatus where both the core (composed of alginate, drug, and Pluronic F127) and shell (composed of only alginate) feed were separately sent to the coaxial ultrasonic atomizer where they were nebulized and placed in contact with the complexation bulk. With the aim to obtain microstructured particles of alginate encapsulating 5-fluorouracil, different formulations of the first complexation bulk were tested; at last an emulsion made of a calcium chloride aqueous solution and dichloromethane allowed to reach an encapsulation efficiency of about 50%. This result can be considered very interesting considering that in literature similar techniques gave 5-fluorouracil encapsulation efficiencies of about 10%. Since a single complexation stage was not able to assure microcarriers gastroresistance, the formulation of a second complexation bulk was evaluated. The solution of cationic and pH-insoluble Eudragit® RS 100 in dichloromethane was chosen as bulk of second-stage complexation obtaining good enteric properties of shell-core microcarriers, i.e. a 5-FU cumulative release at pH 1 (simulating gastric pH) lower than 35%. The formation of interpolyelectrolyte complex (IPEC) between countercharged polymers and the chemical stability of 5-FU in microcarriers were confirmed by FTIR analysis, the presence of an amorphous dispersion of 5-FU in prepared microparticles was also confirmed by DSC. Finally, shell-core enteric coated microcarriers encapsulating 5-fluorouracil were used

  9. The connection between prestellar cores and filaments in the Aquila molecular cloud complex

    NASA Astrophysics Data System (ADS)

    Könyves, Vera; André, Philippe

    2015-08-01

    One of the main scientific goals of the Herschel Gould Belt survey (http://gouldbelt-herschel.cea.fr)is to elucidate the physical mechanisms responsible for the formation and evolution of prestellar cores inmolecular clouds. In the ~ 11 deg2 field of Aquila imaged with Herschel/SPIRE-PACS between 70 and 500microns, we have recently identified a complete sample of 651 starless cores, 446 of them aregravitationally-bound candidate prestellar cores that will likely form stars in the future (Könyves et al. 2010and 2015, submitted - see http://gouldbelt-herschel.cea.fr/archives).Our Herschel observations also provide an unprecedented census of filaments in the Aquila cloud andsuggest an intimate connection between these filaments and the formation process of prestellar cores.About 10%-20% of the gas mass is in the form of filaments below Av ~ 7, while as much as ~ 50%-75%of the dense gas mass above Av ~ 7-10 is in the form of filamentary structures.Furthermore, about 90% of the Herschel-identified prestellar cores are located above a background columndensity corresponding to Av ~ 7, and ~ 75% of them lie within the densest filamentary structures withsupercritical masses per unit length > 16 M⊙/pc. In accordance with this, a strong correlation is foundbetween the spatial distribution of prestellar cores and the densest filaments.Comparing the statistics of cores and filaments with the number of young stellar objects identified bySpitzer in the same complex, we also infer a typical timescale ~ 1 Myr for the formation and evolutionof both prestellar cores and filaments.In summary, our Herschel findings in the Aquila cloud support a filamentary paradigm for the early stagesof star formation, where the cores result primarily from the gravitational fragmentation of marginallysupercritical filaments (cf. André et al. 2014, PPVI).

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

    PubMed

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

    2015-03-05

    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, (1)H 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 (2)B1g 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=0.58μM), compared to the other complexes and the free ligands.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Synthesis of Monomeric Fe(II) and Ru(II) Complexes of Tetradentate Phosphines

    SciTech Connect

    Jana, Barun; Ellern, Arkady; Pestovsky, Oleg; Sadow, Aaron; Bakac, Andreja

    2011-03-07

    rac-Bis[{l_brace}(diphenylphosphino)ethyl{r_brace}-phenylphosphino]methane (DPPEPM) reacts with iron(II) and ruthenium(II) halides to generate complexes with folded DPPEPM coordination. The paramagnetic, five-coordinate Fe(DPPEPM)Cl{sub 2} (1) in CD{sub 2}Cl{sub 2} features a tridentate binding mode as established by {sup 31}P{l_brace}{sup 1}H{r_brace} NMR spectroscopy. Crystal structure analysis of the analogous bromo complex, Fe(DPPEPM)Br{sub 2} (2) revealed a pseudo-octahedral, cis-{alpha} geometry at iron with DPPEPM coordinated in a tetradentate fashion. However, in CD{sub 2}Cl{sub 2} solution, the coordination of DPPEPM in 2 is similar to that of 1 in that one of the external phosphorus atoms is dissociated resulting in a mixture of three tridentate complexes. The chloro ruthenium complex cis-Ru({kappa}{sup 4}-DPPEPM)Cl{sub 2} (3) is obtained from rac-DPPEPM and either [RuCl{sub 2}(COD)]{sub 2} [COD = 1,5-cyclooctadiene] or RuCl{sub 2}(PPh{sub 3}){sub 4}. The structure of 3 in both the solid state and in CD{sub 2}Cl{sub 2} solution features a folded {kappa}{sup 4}-DPPEPM. This binding mode was also observed in cis-[Fe({kappa}{sup 4}-DPPEPM)(CH{sub 3}CN){sub 2}](CF{sub 3}SO{sub 3}){sub 2} (4). Addition of an excess of CO to a methanolic solution of 1 results in the replacement of one of the chloride ions by CO to yield cis-[Fe({kappa}{sup 4}-DPPEPM)Cl(CO)](Cl) (5). The same reaction in CH{sub 2}Cl{sub 2} produces a mixture of 5 and [Fe({kappa}{sup 3}-DPPEPM)Cl{sub 2}(CO)] (6) in which one of the internal phosphines has been substituted by CO. Complexes 2, 3, 4, and 5 appear to be the first structurally characterized monometallic complexes of {kappa}{sup 4}-DPPEPM.

  13. Synthesis, spectral characterization and thermal studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with 2-amino benzoic acid- and 2-hydroxy benzoic acid thiophen-2-ylmethylene hydrazide

    NASA Astrophysics Data System (ADS)

    Singh, Vinod P.; Singh, Pooja

    2013-03-01

    A series of metal complexes of Co(II), Ni(II), Cu(II) and Zn(II) with 2-amino benzoic acid thiophen-2-ylmethylene hydrazide (Habth) and 2-hydroxy benzoic acid thiophen-2-ylmethylene hydrazide (Hhbth) have been synthesized. The complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, electronic, IR, NMR, ESR spectra and thermal studies (TGA and DTA). Molecular structure of the Habth ligand was determined by single crystal X-ray diffraction technique. Habth acts as a monobasic bidentate ligand in all its complexes bonding through a deprotonated Csbnd O- and lbond2 Cdbnd Nsbnd groups whereas, Hhbth acts as a monobasic bidentate in its Co(II) and Ni(II) complexes, bonding through a deprotonated Csbnd O- and lbond2 Cdbnd Nsbnd groups and as monobasic tridentate in Cu(II) and Zn(II) complexes bonding through lbond2 Cdbnd O, lbond2 Cdbnd Nsbnd and deprotonated (Csbnd O)- groups with the metal ion. Electronic spectra suggest a square planar geometry for Co(II), Ni(II) and Cu(II) complexes of Habth and Co(II) and Ni(II) complexes of Hhbth. However, the Cu(II) and Zn(II) complexes of Hhbth have octahedral geometry. The ESR spectra of Cu(II) complex of Hhbth in the solid state and in DMSO frozen solution show axial signals and suggest the presence of unpaired electron in d orbital of Cu(II). The Cu(II) complex of Habth in solid state shows isotropic signal, whereas, axial signal in DMSO frozen solution in the range of tetragonally distorted octahedral geometry due to interactions of DMSO molecules at axial positions. Thermal studies of some of the metal complexes show a multi-step decomposition pattern of bonded ligands in the complex.

  14. Accumulation of Major Histocompatibility Complex Class II Molecules in Mast Cell Secretory Granules and Their Release upon Degranulation

    PubMed Central

    Raposo, Graça; Tenza, Danielle; Mecheri, Salahedine; Peronet, Roger; Bonnerot, Christian; Desaymard, Catherine

    1997-01-01

    To investigate the relationship between major histocompatibility complex (MHC) class II compartments, secretory granules, and secretory lysosomes, we analyzed the localization and fate of MHC class II molecules in mast cells. In bone marrow-derived mast cells, the bulk of MHC class II molecules is contained in two distinct compartments, with features of both lysosomal compartments and secretory granules defined by their protein content and their accessibility to endocytic tracers. Type I granules display internal membrane vesicles and are accessed by exogenous molecules after a time lag of 20 min; type II granules are reached by the endocytic tracer later and possess a serotonin-rich electron-dense core surrounded by a multivesicular domain. In these type I and type II granules, MHC class II molecules, mannose-6-phosphate receptors and lysosomal membrane proteins (lamp1 and lamp2) localize to small intralumenal vesicles. These 60–80-nm vesicles are released along with inflammatory mediators during mast cell degranulation triggered by IgE-antigen complexes. These observations emphasize the intimate connection between the endocytic and secretory pathways in cells of the hematopoietic lineage which allows regulated secretion of the contents of secretory lysosomes, including membrane proteins associated with small vesicles. PMID:9398681

  15. Accumulation of major histocompatibility complex class II molecules in mast cell secretory granules and their release upon degranulation.

    PubMed

    Raposo, G; Tenza, D; Mecheri, S; Peronet, R; Bonnerot, C; Desaymard, C

    1997-12-01

    To investigate the relationship between major histocompatibility complex (MHC) class II compartments, secretory granules, and secretory lysosomes, we analyzed the localization and fate of MHC class II molecules in mast cells. In bone marrow-derived mast cells, the bulk of MHC class II molecules is contained in two distinct compartments, with features of both lysosomal compartments and secretory granules defined by their protein content and their accessibility to endocytic tracers. Type I granules display internal membrane vesicles and are accessed by exogenous molecules after a time lag of 20 min; type II granules are reached by the endocytic tracer later and possess a serotonin-rich electron-dense core surrounded by a multivesicular domain. In these type I and type II granules, MHC class II molecules, mannose-6-phosphate receptors and lysosomal membrane proteins (lamp1 and lamp2) localize to small intralumenal vesicles. These 60-80-nm vesicles are released along with inflammatory mediators during mast cell degranulation triggered by IgE-antigen complexes. These observations emphasize the intimate connection between the endocytic and secretory pathways in cells of the hematopoietic lineage which allows regulated secretion of the contents of secretory lysosomes, including membrane proteins associated with small vesicles.

  16. Theoretical studies on N-O or N-N bond formation from aryl azide catalyzed by iron(II) bromide complex.

    PubMed

    Li, Juan; Zhang, Qi; Zhou, Lixin

    2012-03-02

    DFT calculations have been carried out to study the reaction mechanism on N-O or N-N bond formation from aryl azide catalyzed by iron(II) bromide complex. A favorable reaction pathway is proposed to account for the construction of the core structure of 2H-indazoles or 2,1-benzisoxazoles.

  17. Identifying the lowest electronic states of the chlorophylls in the CP47 core antenna protein of photosystem II.

    PubMed

    De Weerd, Frank L; Palacios, Miguel A; Andrizhiyevskaya, Elena G; Dekker, Jan P; Van Grondelle, Rienk

    2002-12-24

    CP47 is a pigment-protein complex in the core of photosystem II that tranfers excitation energy to the reaction center. Here we report on a spectroscopic investigation of the isolated CP47 complex. By deconvoluting the 77 K absorption and linear dichroism, red-most states at 683 and 690 nm have been identified with oscillator strengths corresponding to approximately 3 and approximately 1 chlorophyll, respectively. Both states contribute to the 4 K emission, and the Stark spectrum shows that they have a large value for the difference polarizability between their ground and excited states. From site-selective polarized triplet-minus-singlet spectra, an excitonic origin for the 683 nm state was found. The red shift of the 690 nm state is most probably due to strong hydrogen bonding to a protein ligand, as follows from the position of the stretch frequency of the chlorophyll 13(1) keto group (1633 cm(-)(1)) in the fluorescence line narrowing spectrum at 4 K upon red-most excitation. We discuss how the 683 and 690 nm states may be linked to specific chlorophylls in the crystal structure [Zouni, A., Witt, H.-T., Kern, J., Fromme, P., Krauss, N., Saenger, W., and Orth, P. (2001) Nature 409, 739-743].

  18. Design and Use of Peptide-Based Antibodies Decreasing Superoxide Production by Mitochondrial Complex I and Complex II

    PubMed Central

    Kang, Patrick T.; Yun, June; Kaumaya, Pravin P.T.; Chen, Yeong-Renn

    2010-01-01

    Mitochondria are the major source of reactive oxygen species. Both complex I and complex II mediate O2•− production in mitochondria and host reactive protein thiols. To explore the functions of the specific domains involved in the redox modifications of complexes I and II, various peptide-based antibodies were generated against these complexes, and their inhibitory effects were subsequently measured. The redox domains involved in S-glutathionylation and nitration, as well as the binding motif of the iron-sulfur cluster (N1a) of the complexes I and II were utilized to design B cell epitopes for generating antibodies. The effect of antibody binding on enzyme-mediated O2•− generation was measured by EPR spin trapping. Binding of either antibody AbGSCA206 or AbGSCB367 against glutathione (GS)-binding domain to complex I inhibits its O2•− generation, but does not affect electron transfer efficiency. Binding of antibody (Ab24N1a) against the binding motif of N1a to complex I modestly suppresses both O2•− generation and electron transfer efficiency. Binding of either antibody Ab75 or Ab24 against non-redox domain decreases electron leakage for O2•− production. In complex II, binding of antibody AbGSC90 against GS-binding domain to complex II marginally decreases both O2•− generation and electron transfer activity. Binding of antibody AbY142 to complex II against the nitrated domain modestly inhibits electron leakage, but does not affect the electron transfer activity of complex II. In conclusion, mediation of O2•− generation by complexes I and II can be regulated by specific redox and non-redox domains. PMID:20564035

  19. Synthesis, characterization, and antioxidant/cytotoxic activity of new chromone Schiff base nano-complexes of Zn(II), Cu(II), Ni(II) and Co(II)

    NASA Astrophysics Data System (ADS)

    Saif, M.; El-Shafiy, Hoda F.; Mashaly, Mahmoud M.; Eid, Mohamed F.; Nabeel, A. I.; Fouad, R.

    2016-08-01

    A chromone Schiff base complexes of Zn(II) (1), Cu(II) (2), Ni(II) (3) and Co(II) (4) were successfully prepared in nano domain with crystalline or amorphous structures. The spectroscopic data revealed that the Schiff base ligand behaves as a monoanionic tridentate ligand. The metal complexes exhibited octahedral geometry. Transmission electron microscope (TEM) analysis showed that Cu(II) complex have aggregated nanospheres morphology. The obtained nano-complexes were tested as antioxidant and antitumor agents. The H2L and its Cu(II) complex (2) were found to be more potent antioxidant (IC50(H2L) = 0.93 μM; IC50(Cu(II) complex) = 1.1 μM than standard ascorbic acid (IC50 = 2.1 μM) as evaluated by DPPH• method. The H2L and its complexes (1-4) were tested for their in vitro cytotoxicity against Ehrlich Ascites Carcinoma cell line (EAC). The Cu(II) nano-complex (2) effectively inhibited EAC growth with IC50 value of 47 μM in comparison with its parent compound and other prepared complexes. The high antioxidant activity and antitumor activity of Cu(II) nano-complex (2) were attributed to their chemical structure, Cu(II) reducing capacity, and nanosize property. The toxicity test on mice showed that Zn(II) (1) and Cu(II) (2) nano-complex have lower toxicity than the standard cis-platin.

  20. Synthesis and characterization of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of chromone based azo-linked Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Anitha, C.; Sheela, C. D.; Tharmaraj, P.; Johnson Raja, S.

    2012-12-01

    Azo-Schiff-base complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized and characterized by elemental analysis, IR, UV-Vis, 1H NMR, mass spectra, molar conductance, magnetic susceptibility measurement, electron spin resonance (EPR), CV, fluorescence, NLO and SEM. The conductance data indicate the nonelectrolytic nature of the complexes, except VO(II) complex which is electrolytic in nature. On the basis of electronic spectra and magnetic susceptibility octahedral geometry has been proposed for the complexes. The EPR spectra of copper and oxovanadium complexes in DMSO at 300 and 77 K were recorded and its salient features are reported. The redox behavior of the copper(II) complex was studied using cyclic voltammetry. The in vitro antimicrobial activity against Staphylococcus aureus, Escherichia coli, Salmonella enterica typhi, Bacillus subtilis and Candida strains was studied and compared with that of free ligand by well-diffusion technique. The azo Schiff base exhibited fluorescence properties originating from intraligand (π-π∗) transitions and metal-mediated enhancement is observed on complexation and so the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. On the basis of the optimized structures, the second-order nonlinear optical properties (NLO) are calculated by using second-harmonic generation (SHG) and also the surface morphology of the complexes was studied by SEM.

  1. Bipyrimidine ruthenium(II) arene complexes: structure, reactivity and cytotoxicity.

    PubMed

    Betanzos-Lara, Soledad; Novakova, Olga; Deeth, Robert J; Pizarro, Ana M; Clarkson, Guy J; Liskova, Barbora; Brabec, Viktor; Sadler, Peter J; Habtemariam, Abraha

    2012-10-01

    The synthesis and characterization of complexes [(η(6)-arene)Ru(N,N')X][PF(6)], where arene is para-cymene (p-cym), biphenyl (bip), ethyl benzoate (etb), hexamethylbenzene (hmb), indane (ind) or 1,2,3,4-tetrahydronaphthalene (thn), N,N' is 2,2'-bipyrimidine (bpm) and X is Cl, Br or I, are reported, including the X-ray crystal structures of [(η(6)-p-cym)Ru(bpm)I][PF(6)], [(η(6)-bip)Ru(bpm)Cl][PF(6)], [(η(6)-bip)Ru(bpm)I][PF(6)] and [(η(6)-etb)Ru(bpm)Cl][PF(6)]. Complexes in which N,N' is 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione or 4,7-diphenyl-1,10-phenanthroline (bathophen) were studied for comparison. The Ru(II) arene complexes undergo ligand-exchange reactions in aqueous solution at 310 K; their half-lives for hydrolysis range from 14 to 715 min. Density functional theory calculations on [(η(6)-p-cym)Ru(bpm)Cl][PF(6)], [(η(6)-p-cym)Ru(bpm)Br][PF(6)], [(η(6)-p-cym)Ru(bpm)I][PF(6)], [(η(6)-bip)Ru(bpm)Cl][PF(6)], [(η(6)-bip)Ru(bpm)Br][PF(6)] and [(η(6)-bip)Ru(bpm)I][PF(6)] suggest that aquation occurs via an associative pathway and that the reaction is thermodynamically favourable when the leaving ligand is I > Br ≈ Cl. pK (a)* values for the aqua adducts of the complexes range from 6.9 to 7.32. A binding preference for 9-ethylguanine (9-EtG) compared with 9-ethyladenine (9-EtA) was observed for [(η(6)-p-cym)Ru(bpm)Cl][PF(6)], [(η(6)-hmb)Ru(bpm)Cl](+), [(η(6)-ind)Ru(bpm)Cl](+), [(η(6)-thn)Ru(bpm)Cl](+), [(η(6)-p-cym)Ru(phen)Cl](+) and [(η(6)-p-cym)Ru(bathophen)Cl](+) in aqueous solution at 310 K. The X-ray crystal structure of the guanine complex [(η(6)-p-cym)Ru(bpm)(9-EtG-N7)][PF(6)](2) shows multiple hydrogen bonding. Density functional theory calculations show that the 9-EtG adducts of all complexes are thermodynamically preferred compared with those of 9-EtA. However, the bmp complexes are inactive towards A2780 human ovarian cancer cells. Calf thymus DNA interactions for [(η(6)-p-cym)Ru(bpm)Cl][PF(6)] and [(η(6)-p

  2. Synthesis, Structure, and Reactivity of Co(II) and Ni(II) PCP Pincer Borohydride Complexes

    PubMed Central

    2015-01-01

    The 15e square-planar complexes [Co(PCPMe-iPr)Cl] (2a) and [Co(PCP-tBu)Cl] (2b), respectively, react readily with NaBH4 to afford complexes [Co(PCPMe-iPr)(η2-BH4)] (4a) and [Co(PCP-tBu)(η2-BH4)] (4b) in high yields, as confirmed by IR spectroscopy, X-ray crystallography, and elemental analysis. The borohydride ligand is symmetrically bound to the cobalt center in η2-fashion. These compounds are paramagnetic with effective magnetic moments of 2.0(1) and 2.1(1) μB consistent with a d7 low-spin system corresponding to one unpaired electron. None of these complexes reacted with CO2 to give formate complexes. For structural and reactivity comparisons, we prepared the analogous Ni(II) borohydride complex [Ni(PCPMe-iPr)(η2-BH4)] (5) via two different synthetic routes. One utilizes [Ni(PCPMe-iPr)Cl] (3) and NaBH4, the second one makes use of the hydride complex [Ni(PCPMe-iPr)H] (6) and BH3·THF. In both cases, 5 is obtained in high yields. In contrast to 4a and 4b, the borohydride ligand is asymmetrically bound to the nickel center but still in an η2-mode. [Ni(PCPMe-iPr)(η2-BH4)] (5) loses readily BH3 at elevated temperatures in the presence of NEt3 to form 6. Complexes 5 and 6 are both diamagnetic and were characterized by a combination of 1H, 13C{1H}, and 31P{1H} NMR, IR spectroscopy, and elemental analysis. Additionally, the structure of these compounds was established by X-ray crystallography. Complexes 5 and 6 react with CO2 to give the formate complex [Ni(PCPMe-iPr)(OC(C=O)H] (7). The extrusion of BH3 from [Co(PCPMe-iPr)(η2-BH4)] (4a) and [Ni(PCPMe-iPr)(η2-BH4)] (5) with the aid of NH3 to yield the respective hydride complexes [Co(PCPMe-iPr)H] and [Ni(PCPMe-iPr)H] (6) and BH3NH3 was investigated by DFT calculations showing that formation of the Ni hydride is thermodynamically favorable, whereas the formation of the Co(II) hydride, in agreement with the experiment, is unfavorable. The electronic structures and the bonding of the borohydride ligand in [Co

  3. Long-rising Type II supernovae from Palomar Transient Factory and Caltech Core-Collapse Project

    NASA Astrophysics Data System (ADS)

    Taddia, F.; Sollerman, J.; Fremling, C.; Migotto, K.; Gal-Yam, A.; Armen, S.; Duggan, G.; Ergon, M.; Filippenko, A. V.; Fransson, C.; Hosseinzadeh, G.; Kasliwal, M. M.; Laher, R. R.; Leloudas, G.; Leonard, D. C.; Lunnan, R.; Masci, F. J.; Moon, D.-S.; Silverman, J. M.; Wozniak, P. R.

    2016-04-01

    Context. Supernova (SN) 1987A was a peculiar hydrogen-rich event with a long-rising (~84 d) light curve, stemming from the explosion of a compact blue supergiant star. Only a few similar events have been presented in the literature in recent decades. Aims: We present new data for a sample of six long-rising Type II SNe (SNe II), three of which were discovered and observed by the Palomar Transient Factory (PTF) and three observed by the Caltech Core-Collapse Project (CCCP). Our aim is to enlarge this small family of long-rising SNe II, characterizing their differences in terms of progenitor and explosion parameters. We also study the metallicity of their environments. Methods: Optical light curves, spectra, and host-galaxy properties of these SNe are presented and analyzed. Detailed comparisons with known SN 1987A-like events in the literature are shown, with particular emphasis on the absolute magnitudes, colors, expansion velocities, and host-galaxy metallicities. Bolometric properties are derived from the multiband light curves. By modeling the early-time emission with scaling relations derived from the SuperNova Explosion Code (SNEC) models of MESA progenitor stars, we estimate the progenitor radii of these transients. The modeling of the bolometric light curves also allows us to estimate other progenitor and explosion parameters, such as the ejected 56Ni mass, the explosion energy, and the ejecta mass. Results: We present PTF12kso, a long-rising SN II that is estimated to have the largest amount of ejected 56Ni mass measured for this class. PTF09gpn and PTF12kso are found at the lowest host metallicities observed for this SN group. The variety of early light-curve luminosities depends on the wide range of progenitor radii of these SNe, from a few tens of R⊙ (SN 2005ci) up to thousands (SN 2004ek) with some intermediate cases between 100 R⊙ (PTF09gpn) and 300 R⊙ (SN 2004em). Conclusions: We confirm that long-rising SNe II with light-curve shapes closely

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

    PubMed

    Chohan, Zahid H; Supuran, Claudiu T

    2006-08-01

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

  5. Chromium(II) and chromium(II) tri-tert-butoxysiloxy complexes

    SciTech Connect

    Terry, K.W.; Gantzel, P.K.; Tilley, T.D. )

    1993-11-10

    The authors have been exploring the structure, bonding, and chemistry of transition-metal and main-group complexes that possess oxygen-rich alkoxysiloxy ligands such as [minus]OSi(O[sup t]Bu)[sub 3]. A primary focus of these studies is the development of molecular, single-source precursors to homogeneous, ultrapure metal silicates. The authors have found that titanium, zirconium, hafnium, and aluminum derivatives of [minus]OSi(O[sup t]Bu)[sub 3] thermally decompose at low temperatures (100-200[degrees]C) with elimination of isobutylene and water to give metal-containing silicates. Previous observations suggested the possible use of this methodology in new syntheses of supported catalysts, particularly since chemical reactivities and selectivities are known to be very sensitive to the size and shape of the supported metal catalyst particles. Silica- and aluminosilica-supported chromium catalysts are used widely for the catalytic polymerization of ethylene. To examine alkoxysiloxy derivatives of chromium as precursors to chromium-supported catalysts, the authors have begun to explore synthetic routes to Cr-OSi(O[sup t]Bu)[sub 3] complexes. On the basis of previously reported routes to siloxide and alkoxide complexes of chromium, approaches based on either the silanol HOSi(O[sup t]Bu)[sub 3] or alkali metal derivatives MOSi(O[sup t]Bu)[sub 3] (M = Li, Na, K) as starting materials seem possible. The authors report two siloxide complexes which result from the reaction of Cr(NEt[sub 2])[sub 4] with HOSi(O[sup t]Bu)[sub 3]. While this reaction does not provide a high yield of a single product that can be used in a convenient route to chromium silicate materials, it does offer the opportunity to closely compare analogous chromium(II) and chromium(III) siloxide complexes Cr[OSi(O[sup t]Bu)[sub 3

  6. Multi-pyridine decorated Fe(II) and Ru(II) complexes by Pd(0)-catalysed cross couplings: new building blocks for metallosupramolecular assemblies.

    PubMed

    Yang, Jiajia; Clegg, Jack K; Jiang, Qibai; Lui, Xiaoming; Yan, Hong; Zhong, Wei; Beves, Jonathon E

    2013-11-28

    Eight metal complexes of the type [M(tpy)2](2+) (tpy = 2,2':6',2''-terpyridine) featuring four pendant pyridine rings are reported and characterised by NMR, MS, absorption spectroscopy and electrochemical methods. Palladium-mediated Suzuki and Sonogashira cross-coupling reactions were performed on both free 4'-(3,5-dibromophenyl)-tpy and its Ru(II) complex in good yields. The ready N-alkylation of the pendant pyridyl units has significant influence on the absorption and electrochemical reduction of the complexes, processes which are localised on the periphery and leaves the [Ru(tpy)2](2+) core essentially unaffected. The binding of metal ions by the free pyridines is also demonstrated as means of assembling larger ordered non-covalent structures.

  7. A curious interplay in the films of N-heterocyclic carbene PtII complexes upon deposition of alkali metals

    PubMed Central

    Makarova, Anna A.; Grachova, Elena V.; Niedzialek, Dorota; Solomatina, Anastasia I.; Sonntag, Simon; Fedorov, Alexander V.; Vilkov, Oleg Yu.; Neudachina, Vera S.; Laubschat, Clemens; Tunik, Sergey P.; Vyalikh, Denis V.

    2016-01-01

    The recently synthesized series of PtII complexes containing cyclometallating (phenylpyridine or benzoquinoline) and N-heterocyclic carbene ligands possess intriguing structures, topologies, and light emitting properties. Here, we report curious physicochemical interactions between in situ PVD-grown films of a typical representative of the aforementioned PtII complex compounds and Li, Na, K and Cs atoms. Based on a combination of detailed core-level photoelectron spectroscopy and quantum-chemical calculations at the density functional theory level, we found that the deposition of alkali atoms onto the molecular film leads to unusual redistribution of electron density: essential modification of nitrogen sites, reduction of the coordination PtII centre to Pt0 and decrease of electron density on the bromine atoms. A possible explanation for this is formation of a supramolecular system “Pt complex-alkali metal ion”; the latter is supported by restoration of the system to the initial state upon subsequent oxygen treatment. The discovered properties highlight a considerable potential of the PtII complexes for a variety of biomedical, sensing, chemical, and electronic applications. PMID:27151364

  8. FANCI Regulates Recruitment of the FA Core Complex at Sites of DNA Damage Independently of FANCD2.

    PubMed

    Castella, Maria; Jacquemont, Celine; Thompson, Elizabeth L; Yeo, Jung Eun; Cheung, Ronald S; Huang, Jen-Wei; Sobeck, Alexandra; Hendrickson, Eric A; Taniguchi, Toshiyasu

    2015-10-01

    The Fanconi anemia (FA)-BRCA pathway mediates repair of DNA interstrand crosslinks. The FA core complex, a multi-subunit ubiquitin ligase, participates in the detection of DNA lesions and monoubiquitinates two downstream FA proteins, FANCD2 and FANCI (or the ID complex). However, the regulation of the FA core complex itself is poorly understood. Here we show that the FA core complex proteins are recruited to sites of DNA damage and form nuclear foci in S and G2 phases of the cell cycle. ATR kinase activity, an intact FA core complex and FANCM-FAAP24 were crucial for this recruitment. Surprisingly, FANCI, but not its partner FANCD2, was needed for efficient FA core complex foci formation. Monoubiquitination or ATR-dependent phosphorylation of FANCI were not required for the FA core complex recruitment, but FANCI deubiquitination by USP1 was. Additionally, BRCA1 was required for efficient FA core complex foci formation. These findings indicate that FANCI functions upstream of FA core complex recruitment independently of FANCD2, and alter the current view of the FA-BRCA pathway.

  9. Spectroscopic evaluation for VO(II), Ni(II), Pd(II) and Cu(II) complexes derived from thiosemicarbazide: A special emphasis on EPR study and DNA cleavage

    NASA Astrophysics Data System (ADS)

    El-Metwally, Nashwa M.; Al-Hazmi, Gamil A. A.

    2013-04-01

    Some thiosemicarbazide complexes were prepared and deliberately investigated by all allowed tools. The ligand coordinates as a mono negative bidentate towards VO(II) and Ni(II) as well as a neutral bidentate towards Pd(II) and Cu(II) ions. Electronic spectral data beside the magnetic measurements facilitate the structural geometry proposal. EPR spectra of Cu(II) and VO(II) complexes were recorded in their solid state. Spin Hamiltonian parameters and molecular orbital coefficient for Cu(II) and VO(II) complexes were calculated and supporting the octahedral geometry of Cu(II) complex and a square pyramidal for VO(II) one. The biological activity investigation was studied by the use of all prepared compounds. The VO(II) and Cu(II) complexes display the susceptible biotoxicity against a gram-positive bacterium. Also, Cu(II) complex displays the same toxicity against gram-negative bacteria used. The effect of all compounds on DNA were photographed. A successive degradation for the DNA target was observed with Pd(II) and Ni(II) complexes beside their original ligand.

  10. Strike-slip accommodated core complexes in the Najd fault system, Arabian-Nubian shield

    NASA Astrophysics Data System (ADS)

    Meyer, S. E.; Passchier, C. W.; Abu-Alam, T. S.; Stuewe, K.

    2013-12-01

    Metamorphic core complexes are usually developed as extensional features during crustal thinning in a continental collision zone, such as the Basin and Range and the Aegean Terrane. The Najd fault system in Saudi Arabia is a 2000 km-long and 400 km-wide complex network of crustal-scale strike-slip shear zones in a Neoproterozoic collision zone. Locally, the anastomosing shear zones lead to exhumation of lower crustal segments and represent a new kinematic model for the development of core complexes. We report on two such dome structures: the Qazaz complex in Saudi Arabia and the Hafafit complex in Egypt. The 15-km-wide Qazaz complex is a triangular dome of gently dipping mylonitic foliations within the 140-km-long sinistral strike-slip Qazaz mylonite zone. The gneissic dome consists of high-grade rocks, surrounded by low-grade metasediments and metavolcanics. The main SE trending strike-slip Qazaz shear zone splits southwards into two branches around the gneiss dome: the western branch is continuous with the shallow dipping mylonites of the dome core, without overprinting, and curves by more than 90 degrees eastwards from a NS trending strike slip zone to an EW trending 40 degree south dipping detachment that bounds the gneiss dome to the south. The eastern SE trending sinistral strike slip shear zone branch is slightly younger and transects the central dome fabrics. The gneiss dome appears to have formed along a jog in the strike slip shear zone during 40 km of strike slip motion, which caused local exhumation of lower crustal rocks by 25 km along the detachment. The eastern shear zone branch formed late during exhumation, transacted the gneiss dome and offset the two parts by another 70 km. The Hafafit core complex in Egypt is of similar shape and size to the Qazaz structure, but forms the northern termination of a sinistral strike-slip zone that is at least 100 km in length. This zone may continue into Saudi Arabia as the Ajjaj shear zone for another 100 km. The

  11. Spectroscopic characterization, antioxidant and antitumour studies of novel bromo substituted thiosemicarbazone and its copper(II), nickel(II) and palladium(II) complexes

    NASA Astrophysics Data System (ADS)

    Jagadeesh, M.; Lavanya, M.; Kalangi, Suresh K.; Sarala, Y.; Ramachandraiah, C.; Varada Reddy, A.

    2015-01-01

    A new, slightly distorted octahedral complex of copper(II), square planar complexes of nickel(II) and palladium(II) with 2,4‧-dibromoacetophenone thiosemicarbazone (DBAPTSC) are synthesized. The ligand and the complexes are characterized by FT-IR, FT-Raman, powder X-ray diffraction studies. The IR and Raman data are correlated for the presence of the functional groups which specifically helped in the confirmation of the compounds. In addition, the free ligand is unambiguously characterized by 1H and 13C NMR spectroscopy while the copper(II) complex is characterized by electron paramagnetic resonance spectroscopy (EPR). The g values for the same are found to be 2.246 (g1), 2.012 (g2) and 2.005 (g3) which suggested rhombic distortions. The HOMO-LUMO band gap calculations for these compounds are found to be in between 0.5 and 4.0 eV and these compounds are identified as semiconducting materials. The synthesized ligand and its copper(II), nickel(II) and palladium(II) complexes are subjected to antitumour activity against the HepG2 human hepatoblastoma cell lines. Among all the compounds, nickel(II) complex is found to exert better antitumour activity with 57.6% of cytotoxicity.

  12. Synthesis, physico-chemical investigations of Co(II), Ni(II) and Cu(II) complexes and their in vitro microbial, cytotoxic, DNA cleavage studies.

    PubMed

    Bagihalli, Gangadhar B; Patil, Sangamesh A

    2010-06-01

    A series of metal complexes of cobalt(II), nickel(II), and copper(II) have been synthesized with newly derived biologically active ligands. These ligands were synthesized by the condensation of 2-amino-4-phenyl-1,3-thiazole with 8-formyl-7-hydroxy- 4-methylcoumarin. The probable structure of the complexes has been proposed on the basis of analytical and spectroscopic data (IR, UV-Vis, ESR, FAB-mass, and thermoanalytical). Electrochemical study of the complexes is also reported. Elemental analysis of the complexes confined them to stoichiometry of the type ML(2).2H(2)O [M = Co(II), Ni(II), and Cu(II)]. The Schiff base and its metal(II) complexes have been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Staphylococcus pyogenes, and Pseudomonas aeruginosa) and antifungal activities (Aspergillus niger, Aspergillus flavus, and Cladosporium) by the MIC method. The brine shrimp bioassay was carried out to study their in vitro cytotoxic properties, and also the Schiff base and its metal(II) complexes have been studied for DNA cleavage.

  13. Recombinant Reconstitution and Purification of the IFT-B Core Complex from Chlamydomonas reinhardtii.

    PubMed

    Taschner, Michael; Lorentzen, Esben

    2016-01-01

    Eukaryotic cilia and flagella are assembled and maintained by intraflagellar transport (IFT), the bidirectional transport of proteins between the ciliary base and tip. IFT is mediated by the multi-subunit IFT complex, which simultaneously binds cargo proteins and the ciliary motors. So far 22 subunits of the IFT complex have been identified, but insights into the biochemical architecture and especially the three-dimensional structure of this machinery are only starting to emerge because of difficulties in obtaining homogeneous material suitable for structural analysis. Here, we describe a protocol for the purification and reconstitution of a complex containing nine Chlamydomonas reinhardtii IFT proteins, commonly known as the IFT-B core complex. In our hands, this protocol routinely yields several milligrams of pure complex suitable for structural analysis by X-ray crystallography and single-particle cryo-electron microscopy.

  14. The Death Throes of Ocean Core Complexes: Examples from the Mid-Cayman Spreading Centre

    NASA Astrophysics Data System (ADS)

    Cheadle, M. J.; John, B. E.; German, C. R.; Kusznir, N. J.

    2012-12-01

    The Mid-Cayman Spreading Centre (MCSC) is an ultraslow (full rate 15-17 mm/yr) mid-ocean ridge that is located within the Cayman Trough, at the boundary between the North American and Caribbean plates. It is 110km long, and at ~6km below sea level, is the deepest spreading centre in the world. In the Summer of 2011, during NOAA EX 1104, the RV Okeanos Explorer collected high resolution (50m) Simrad EM302 multibeam bathymetry, and high-resolution video using the ROV Little Hercules ,which together provide insight into the evolution (from birth to death) of oceanic core complexes (OCCs). The MCSC exhibits bathymetry typical of slow spreading, magmatically deficient, ridges with thick lithosphere. It has both well-developed OCCs with ~15km of detachment fault offset and smaller offset (6-7km) normal faults forming >40km long linear ridges. Mass wasting is conspicuous. The MCSC is flanked on both sides by three oceanic core complexes: i) the now inactive, Mount Emms to the northeast, ii) the near-recently active Mount Dent in the west centre of the axial valley, and iii) the decapitated Mount Hudson on the south east flank. Together these massifs show different stages of OCC termination. Mount Emms lies approximately 2Ma off axis, is the oldest of the OCCs, and is heavily dissected by faulting and mass wasting. Mount Hudson is terminated by a west dipping high angle normal fault, with 1.6km throw and was initially rifted apart ~0.5Ma. A recently active axial volcanic ridge (AVR) with ROV observed pahoehoe lava forms, and a line of conical volcanic edifices lie within the rifted remains at the toe of the OCC. In contrast, Mount Dent was the most recently active, but is now in the very initial stages of being rifted apart by the presently active AVR that currently intersects the OCC. Incipient high angle normal faults that lie along strike of the AVR cut the dome of Mount Dent, and host the active von Damm hydrothermal system. Mount Dent also shows excess (>1km) uplift

  15. Felodipine β-cyclodextrin complex as an active core for time delayed chronotherapeutic treatment of hypertension.

    PubMed

    Pagar, Kunal P; Vavia, Pradeep R

    2012-11-01

    The present research work deals with the development of a time delayed chronotherapeutic formulation of felodipine (FD) aimed at rapid drug release after a desired lag time in the management of hypertension. The developed system comprises a drug core embedded within a swellable layer and coated with an insoluble, water permeable polymeric system. FD cyclodextrin complex was used as an active core while ethyl cellulose was used as an effective coating layer. Dissolution studies of the complex revealed that there was a 3-fold increase in dissolution of the complex compared to plain FD. This dissolution enhancement and rapid drug release resulted from FD amorphisation, as confirmed by XRD, DSC and SEM studies. FTIR and ¹H NMR studies confirmed the complex formation between FD and cyclodextrin based on the observed hydrogen bond interactions. FD release was adequately adjusted by using a pH independent polymer, i.e., ethyl cellulose, along with dibutyl phthalate as plasticizer. Influence of formulation variables like polymer viscosity, plasticizer concentration, super disintegrant concentration in the swellable layer and percent coating weight gain was investigated to characterize the lag time. Upon permeation of water, the core tablet swelled, resulting in the rupture of the coating layer, followed by rapid drug release. The developed formulation of FD showed a lag time of 5-7 h, which is desirable for chronotherapeutic application.

  16. Organic light-emitting diodes incorporating nanometer thick films of europium-cored complexes

    NASA Astrophysics Data System (ADS)

    Phelan, Gregory D.; Carlson, Brenden; Jiang, Xuezhong; Jen, Alex K. Y.; Dalton, Larry R.

    2002-11-01

    Europium cored complexes may be used as a source of red emission in light emitting diodes. Novel europium cored complexes have been synthesized and incorporated into organic light emitting diodes (OLED's). These complexes emit red light at 615 nm with a full width half maximum (FWHM) of less than 5 nm. The europium complexes consist of one equivalent of europium chelated to three equivalents of a nonsymmetrical β-diketone ligand. The Claissen condensation of a polycyclic aromatic sensitizer and an ester of a fluorinated carboxylic acid create the ligands. The use of a sensitizer such as phenanthrene results in a ligand that has an emission band that directly overlaps with the absorption band of europium. The use of fluorinated chains improves the overall processibility as well as the charge transfer capability of the resulting metal cored complex. The europium core is further encapsulated by the inclusion of an additional polycyclic aromatic compound such as 4, 7 diphenyl - 1, 10 phenanthroline. Emission of 615 nm light is accomplished through excitation of the ligand and efficient Forrester energy transfer to the europium complex. A multiple layer device consisting of a substrate of indium tin oxide, followed by thin layers of BTPD-PFCB (with a thickness of 20nm), a polymer blend containing the europium complex (30 nm), followed by a layer of calcium (50nm) and finally a protective layer of silver (120 nm). The polymer blends were either poly(n-vinyl carbazole)(PVK) or poly vinyl naphthalene (PVN). The device performance was further improved by the incorporation of another lanthanide metal complex. These complexes were based upon similar ligands surrounding gadolinium. In these devices, there is a Dexter energy transfer as well as the Forster energy transfer. For the devices that are based on a PVN:PBD as a polymer host, the lowest turn on voltage was 12.0 volts. The devices that use PVK:TPD devices was 178 cd/m2 with an external quantum efficiency of 0.61%.For

  17. Physicochemical impact studies of gamma rays on "aspirin" analgesics drug and its metal complexes in solid form: Synthesis, spectroscopic and biological assessment of Ca(II), Mg(II), Sr(II) and Ba(II) aspirinate complexes

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; Sharshar, T.; Elsabawy, Khaled M.; Heiba, Zein K.

    2013-09-01

    Metal aspirinate complexes, M2(Asp)4, where M is Mg(II), Ca(II), Sr(II) or Ba(II) are formed by refluxed of aspirin (Asp) with divalent non-transition metal ions of group (II) and characterized by elemental analysis and spectroscopic measurements (infrared, electronic, 1H NMR, Raman, X-ray powder diffraction and scanning electron microscopy). Elemental analysis of the chelates suggests the stoichiometry is 1:2 (metal:ligand). Infrared spectra of the complexes agree with the coordination to the central metal atom through three donation sites of two oxygen atoms of bridge bidentate carboxylate group and oxygen atom of sbnd Cdbnd O of acetyl group. Infrared spectra coupled with the results of elemental analyzes suggested a distorted octahedral structure for the M(II) aspirinate complexes. Gamma irradiation was tested as a method for stabilization of aspirin as well as their complexes. The effect of gamma irradiation, with dose of 80 Gy, on the properties of aspirinate complexes was studied. The aspirinate chelates have been screened for their in vitro antibacterial activity against four bacteria, gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two strains of fungus (Aspergillus flavus and Candida albicans). The metal chelates were shown to possess more antibacterial activity than the free aspirin chelate.

  18. Nuclear structure and the fate of core collapse (Type II) supernova

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    2014-08-01

    For a long time Gerry Brown and his collaborator Hans Bethe considered the question of the final fate of a core collapse (Type II) supernova. Recalling ideas from nuclear structure on Kaon condensate and a soft equation of state of the dense nuclear matter they concluded that progenitor stars with mass as low as 17-18M⊙ (including supernova 1987A) could collapse to a small mass black hole with a mass just beyond 1.5M⊙, the upper bound they derive for a neutron star. We discuss another nuclear structure effect that determines the carbon to oxygen ratio (C/O) at the end of helium burning. This ratio also determines the fate of a Type II supernova with a carbon rich progenitor star producing a neutron star and oxygen rich collapsing to a black hole. While the C/O ratio is one of the most important nuclear inputs to stellar evolution it is still not known with sufficient accuracy. We discuss future efforts to measure with gamma-beam and TPC detector of the C12(α,γ)O16 reaction that determines the C/O ratio in stellar helium burning.

  19. Complex Type-II Interband Cascade MQW Photodetectors

    NASA Technical Reports Server (NTRS)

    Yang, Rui

    2007-01-01

    Multiple-quantum-well (MQW) photodetectors of a proposed type would contain active regions comprising multiple superlattice subregions. These devices would have complex structures: The superlattice of each subregion would be designed for enhanced absorption of photons in a desired wavelength band (typically in the infrared) and multiple subregions of different design would be cascaded for multicolor operation. The designs of these photodetectors would take advantage of the characteristic alignment of the edges of the electron-energy bands in type-II quantum-well structures: Within each finite superlattice, interband transitions would be used for detecting photons, and between finite superlattices, intraband relaxation and interband tunneling would be used for transport of charge carriers, all such as to enable detection of normally incident photons. Absorption of photons in the active region of a photodetector according to the proposal could be significantly enhanced by designing the superlattice/MQW structures to contain closely spaced energy states. The photodetector could be operated with a small bias to facilitate transport of charge carriers. The superlattices could be somewhat chirped, with a preferred transport direction.

  20. A comparative DFT study on aquation and nucleobase binding of ruthenium (II) and osmium (II) arene complexes.

    PubMed

    Wang, Hanlu; Zeng, Xingye; Zhou, Rujin; Zhao, Cunyuan

    2013-11-01

    The potential energy surfaces of the reactions of organometallic arene complexes of the type [(η (6)-arene)M(II)(pic)Cl] (where pic = 2-picolinic acid, M = Ru or Os) were examined by a DFT computational study. Among the seven density functional methods, hybrid exchange functional B3LYP outperforms the others to explain the aquation of the complexes. The reactions and binding energies of Ru(II) and Os(II) arene complexes with both 9EtG and 9EtA were studied to gain insight into the reactivity of these types of organometallic complexes with DNA. The obtained data rationalize experimental observation, contributing to partly understanding the potential biological and medical applications of organometallic complexes.

  1. Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) new complexes of 5-aminosalicylic acid: Spectroscopic, thermal characterization and biological activity studies

    NASA Astrophysics Data System (ADS)

    Soliman, Madiha H.; Mohamed, Gehad G.

    2013-04-01

    The complexing behavior of mesalazine (5-aminosalicylic acid; 5-ASA) towards the transition metal ions namely, Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) have been examined by elemental analyses, magnetic measurements, electronic, IR and 1H NMR. Thermal properties and decomposition kinetics of all complexes are investigated. The interpretation, mathematical analyses and evaluation of kinetic parameters of all thermal decomposition stages have been evaluated using Coats-Redfern equation. The free ligand and its metal complexes have been tested in vitro against Aspergillus fumigatus and Candida albicans fungi and Pseudomonas aeruginosa, Escherichia coli, Bacillis subtilies and Staphylococcus aureus bacteria in order to assess their antimicrobial potential. The results indicate that the metal complexes are also found to have more antimicrobial activity than the parent 5-ASA drug.

  2. Coordination behavior of tetraaza [N4] ligand towards Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes: Synthesis, spectroscopic characterization and anticancer activity

    NASA Astrophysics Data System (ADS)

    El-Boraey, Hanaa A.

    2012-11-01

    Novel eight Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes with [N4] ligand (L) i.e. 2-amino-N-{2-[(2-aminobenzoyl)amino]ethyl}benzamide have been synthesized and structurally characterized by elemental analysis, spectral, thermal (TG/DTG), magnetic, and molar conductivity measurements. On the basis of IR, mass, electronic and EPR spectral studies an octahedral geometry has been proposed for Co(II), Ni(II) complexes and Cu(II) chloride complex, square-pyramidal for Cu(I) bromide complex. For Cu(II) nitrate complex (6), Pd(II) complex (8) square planar geometry was proposed. The EPR data of Cu(II) complexes in powdered form indicate dx2-y2 ground state of Cu(II) ion. The antitumor activity of the synthesized ligand and some selected metal complexes has been studied. The palladium(II) complex (8) was found to display cytotoxicity (IC50 = 25.6 and 41 μM) against human breast cancer cell line MCF-7 and human hepatocarcinoma HEPG2 cell line.

  3. A dual-emissive ionic liquid based on an anionic platinum(ii) complex.

    PubMed

    Ogawa, Tomohiro; Yoshida, Masaki; Ohara, Hiroki; Kobayashi, Atsushi; Kato, Masako

    2015-09-07

    An ionic liquid fabricated from an anionic cyclometalated platinum(ii) complex and an imidazolium cation exhibits dual emission from the monomeric and aggregated forms of the platinum complex anions, leading to temperature-dependent color changes of luminescence.

  4. Synthesis, spectral, and thermal characterizations of Ni(II) and Cu(II) β-diketone complexes with thenoyltrifluoroacetone ligand

    NASA Astrophysics Data System (ADS)

    Chen, Zhimin; Wu, Yiqun; Huang, Fuxin; Gu, Donghong; Gan, Fuxi

    2007-04-01

    Two kinds of nickel(II) and copper(II) β-diketone complexes derived from thenoyltrifluoroacetone ligand with blue-violet light absorption were synthesized by reacting free ligand and different metal(II) ions in sodium methoxide solution. Their structures were postulated based on elemental analysis, ESI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films on K9 glass substrates were prepared using the spin-coating method. Their solubility in organic solvents, absorption properties of thin film and thermal stability of these complexes were evaluated.

  5. Synthesis, spectral, and thermal characterizations of Ni(II) and Cu(II) beta-diketone complexes with thenoyltrifluoroacetone ligand.

    PubMed

    Chen, Zhimin; Wu, Yiqun; Huang, Fuxin; Gu, Donghong; Gan, Fuxi

    2007-04-01

    Two kinds of nickel(II) and copper(II) beta-diketone complexes derived from thenoyltrifluoroacetone ligand with blue-violet light absorption were synthesized by reacting free ligand and different metal(II) ions in sodium methoxide solution. Their structures were postulated based on elemental analysis, ESI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films on K9 glass substrates were prepared using the spin-coating method. Their solubility in organic solvents, absorption properties of thin film and thermal stability of these complexes were evaluated.

  6. Thermal Studies of Zn(II), Cd(II) and Hg(II) Complexes of Some N-Alkyl-N-Phenyl-Dithiocarbamates

    PubMed Central

    Onwudiwe, Damian C.; Ajibade, Peter A.

    2012-01-01

    The thermal decomposition of Zn(II), Cd(II) and Hg(II) complexes of N-ethyl-N-phenyl and N-butyl-N-phenyl dithiocarbamates have been studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The products of the decomposition, at two different temperatures, were further characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results show that while the zinc and cadmium complexes undergo decomposition to form metal sulphides, and further undergo oxidation forming metal oxides as final products, the mercury complexes gave unstable volatiles as the final product. PMID:22949811

  7. Metamorphic core complexes: Expression of crustal extension by ductile-brittle shearing of the geologic column

    NASA Technical Reports Server (NTRS)

    Davis, G. H.

    1985-01-01

    Metamorphic core complexes and detachment fault terranes in the American Southwest are products of stretching of continental crust in the Tertiary. The physical and geometric properties of the structures, fault rocks, and contact relationships that developed as a consequence of the extension are especially well displayed in southeastern Arizona. The structures and fault rocks, as a system, reflect a ductile-through-brittle continuum of deformation, with individual structures and faults rocks showing remarkably coordinated strain and displacement patterns. Careful mapping and analysis of the structural system has led to the realization that strain and displacement were partitioned across a host of structures, through a spectrum of scales, in rocks of progressively changing rheology. By integrating observations made in different parts of the extensional system, especially at different inferred depth levels, it has been possible to construct a descriptive/kinematic model of the progressive deformation that achieved continental crustal extension in general, and the development of metamorphic core complexes in particular.

  8. Structure and Cellular Roles of the RMI Core Complex from the Bloom Syndrome Dissolvasome

    SciTech Connect

    Hoadley, Kelly A.; Xu, Dongyi; Xue, Yutong; Satyshur, Kenneth A.; Wang, Weidong; Keck, James L.

    2010-11-11

    BLM, the protein product of the gene mutated in Bloom syndrome, is one of five human RecQ helicases. It functions to separate double Holliday junction DNA without genetic exchange as a component of the dissolvasome, which also includes topoisomerase III{alpha} and the RMI (RecQ-mediated genome instability) subcomplex (RMI1 and RMI2). We describe the crystal structure of the RMI core complex, comprising RMI2 and the C-terminal OB domain of RMI1. The overall RMI core structure strongly resembles two-thirds of the trimerization core of the eukaryotic single-stranded DNA-binding protein, Replication Protein A. Immunoprecipitation experiments with RMI2 variants confirm key interactions that stabilize the RMI core interface. Disruption of this interface leads to a dramatic increase in cellular sister chromatid exchange events similar to that seen in BLM-deficient cells. The RMI core interface is therefore crucial for BLM dissolvasome assembly and may have additional cellular roles as a docking hub for other proteins.

  9. Mitochondrial Ca2+ influx targets cardiolipin to disintegrate respiratory chain complex II for cell death induction

    PubMed Central

    Hwang, M-S; Schwall, C T; Pazarentzos, E; Datler, C; Alder, N N; Grimm, S

    2014-01-01

    Massive Ca2+ influx into mitochondria is critically involved in cell death induction but it is unknown how this activates the organelle for cell destruction. Using multiple approaches including subcellular fractionation, FRET in intact cells, and in vitro reconstitutions, we show that mitochondrial Ca2+ influx prompts complex II of the respiratory chain to disintegrate, thereby releasing an enzymatically competent sub-complex that generates excessive reactive oxygen species (ROS) for cell death induction. This Ca2+-dependent dissociation of complex II is also observed in model membrane systems, but not when cardiolipin is replaced with a lipid devoid of Ca2+ binding. Cardiolipin is known to associate with complex II and upon Ca2+ binding coalesces into separate homotypic clusters. When complex II is deprived of this lipid, it disintegrates for ROS formation and cell death. Our results reveal Ca2+ binding to cardiolipin for complex II disintegration as a pivotal step for oxidative stress and cell death induction. PMID:24948011

  10. Dinuclear cadmium(II), zinc(II), and manganese(II), trinuclear nickel(II), and pentanuclear copper(II) complexes with novel macrocyclic and acyclic Schiff-base ligands having enantiopure or racemic camphoric diamine components.

    PubMed

    Jiang, Jue-Chao; Chu, Zhao-Lian; Huang, Wei; Wang, Gang; You, Xiao-Zeng

    2010-07-05

    Four novel [3 + 3] Schiff-base macrocyclic ligands I-IV condensed from 2,6-diformyl-4-substituted phenols (R = CH(3) or Cl) and enantiopure or racemic camphoric diamines have been synthesized and characterized. Metal-ion complexations of these enantiopure and racemic [3 + 3] macrocyclic ligands with different cadmium(II), zinc(II), manganese(II), nickel(II), and copper(II) salts lead to the cleavage of Schiff-base C horizontal lineN double bonds and subsequent ring contraction of the macrocyclic ligands due to the size effects and the spatial restrictions of the coordination geometry of the central metals, the steric hindrance of ligands, and the counterions used. As a result, five [2 + 2] and one [1 + 2] dinuclear cadmium(II) complexes (1-6), two [2 + 2] dinuclear zinc(II) (7 and 8), and two [2 + 2] dinuclear manganese(II) (9 and 10) complexes together with one [1 + 1] trinuclear nickel(II) complex (11) and one [1 + 2] pentanuclear copper(II) complex (12), bearing enantiopure or racemic ligands, different substituent groups in the phenyl rings, and different anionic ligands (Cl(-), Br(-), OAc(-), and SCN(-)), have been obtained in which the chiral carbon atoms in the camphoric backbones are arranged in different ways (RRSS for the enantiopure ligands in 1, 2, 4, 5, and 7-10 and RSRS for the racemic ligands in 3, 6, 11, and 12). The steric hindrance effects of the methyl group bonded to one of the chiral carbon atoms of camphoric diamine units are believed to play important roles in the formation of the acyclic [1 + 1] trinuclear complex 11 and [1 + 2] dinuclear and pentanuclear complexes 6 and 12. In dinuclear cadmium(II), zinc(II), and manganese(II) complexes 1-10, the sequence of separations between the metal centers is consistent with that of the ionic radii shortened from cadmium(II) to manganese(II) to zinc(II) ions. Furthermore, UV-vis, circular dichroism, (1)H NMR, and fluorescence spectra have been used to characterize and compare the structural

  11. Fluorescence enhancement of europium complexes by core-shell Ag@SiO₂ nanoparticles.

    PubMed

    Zhang, Hai-Xia; Lin, Xue-Mei; Wang, Ai-Ling; Zhao, Yong-Liang; Chu, Hai-Bin

    2015-12-05

    Three kinds of core-shell Ag@SiO2 nanoparticles with shell thickness of around 10, 15, and 25 nm, respectively, have been prepared by modified Stöber method and used for fluorescence enhancement. Six kinds of europium complexes with halobenzoic acid have been synthesized. Elemental analysis and lanthanide coordination titration show that the complexes have the compositions of Eu(p-XBA)3·H2O and Eu(o-XBA)3·2H2O (X=F, Cl, Br). The fluorescence spectra investigation indicates that the introduction of Ag@SiO2 nanoparticles into the europium complexes' solution can significantly enhance the fluorescence intensities of the complexes. The sequence of enhancement factors for halobenzoic acid complexes with different halogen atoms is Fcomplexes increase. When the thickness of the SiO2 shell is 25 nm, the fluorescence intensity of the europium complexes can reach a maximum enhancement factor of 5.1. The fluorescence enhancement mechanism may be the metal-enhanced fluorescence resulting from surface plasmon resonance of nanoparticles. And the nanoparticles near the complexes can effectively prevent complexes from the interaction with the solvent molecules, leading to a decrease of nonradiative energy transfer and the suppression of luminescence quench.

  12. Transition Metal(II) Complexes with Cefotaxime-Derived Schiff Base: Synthesis, Characterization, and Antimicrobial Studies

    PubMed Central

    Amzoiu, Emilia; Spînu, Cezar Ionuţ

    2014-01-01

    New [ML2(H2O)2] 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. PMID:24688454

  13. XAFS study of bioactive Cu(II) complexes of 7-hydroxycoumarin derivatives in organic solvents

    NASA Astrophysics Data System (ADS)

    Klepka, M. T.; Wolska, A.; Drzewiecka-Antonik, A.; Rejmak, P.; Hatada, K.; Aquilanti, G.

    2017-04-01

    We characterize the structure of two Cu(II) complexes of 7-hydroxycoumarins in organic solvents. The solvents are, dimethyl sulfoxide and dimethylformamide. X-ray absorption spectroscopy together with density functional theory calculations are employed to identify the structural changes induced by the two solvents in comparison to the solid form of complexes. We show that the structure of the Cu(II) complexes is modified depending on the solvent and we propose the geometry of the complexes molecule.

  14. Synthesis, spectroscopic, anticancer and antibacterial studies of Ni(II) and Cu(II) complexes with 2-carboxybenzaldehyde thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Vandana

    2014-08-01

    Ni(II) and Cu(II) complexes of 2-carboxybenzaldehyde thiosemicarbazone (L) were synthesized and investigated by their spectral and analytical data. These newly synthesized complexes have a composition of M(L)X(H2O)2 (where M = Ni(II), Cu(II) and X = Cl-, NO3-, CH3COO-) and (L) is the tridentate Schiff base ligand. The ligand and its complexes have been characterized on the basis of analytical, molar conductivity, magnetic susceptibility measurements, FT-IR, ESR, 1H NMR and electronic spectral analysis. All the compounds were non-electrolytic in nature. On the basis of spectral studies an octahedral geometry has been assigned for Ni(II) and a tetragonal geometry for Cu(II) complexes. The ligand and its metal complexes were screened for their anticancer studies against human breast cancer cell lines MCF-7 and calculated minimum inhibitory concentration and also for antibacterial activity using Kirby-Bauer single disk susceptibility test.

  15. Determination of stability constants of Cu(I), Cd(II) & Zn(II) complexes with thiols using fluorescent probes.

    PubMed

    Walsh, Michael J; Ahner, Beth A

    2013-11-01

    Fluorometric competing-ligand titrations were used to measure stability constants of Zn(II), Cd(II) and Cu(I) complexes of cysteine and glutathione (GSH). Cu(I)-stability constants were also determined for the dipeptides Arg-Cys and Gln-Cys which are produced by a marine alga under copper stress. The fluorescent ion indicators FluoZin-1 and BTC (Invitrogen) were used as competing ligands in titrations involving Zn(II) and Cd(II). Phen Green SK (Invitrogen) was likewise used in Cu(I) titrations. Conditional and cumulative general stability constants were determined using a least squares fit of the titration data to speciation models. The measured stability constants of Cd(II) and Zn(II) complexes were consistent with previous work, validating our method and assumptions. Our results also include the first general stability constants for Cu(I)-cysteine complexes and an alternative set for Cu(I)-GSH complexes. While these stability constants indicate that Cu(I) forms strong complexes with thiols, they are not strong enough to effectively buffer Cu(I) in seawater.

  16. Photochemistry and DNA photocleavage by a new unsupported dirhodium(II,II) complex.

    PubMed

    Li, Zhanyong; Burya, Scott J; Turro, Claudia; Dunbar, Kim R

    2013-07-28

    The new complex [Rh2(phen)2(CH3CN)6](BF4)4 (1) was synthesized and characterized in solution and its crystal structure was determined. Irradiation of 1 with visible light (λirr>590 nm) in water results in the release of two equatorial CH3CN ligands, CH3CNeq, as well as in the formation of mononuclear radical Rh(II) fragments stemming from the homolytic photocleavage of the metal-metal bond. The photoproducts, identified by electrospray ionization mass spectrometry, include [Rh(phen)(CH3CN)(OH)](+) and [Rh(phen)(CH3CN)(H2O)3(BF4)](+). The quantum yield for the photochemical transformation of 1 in H2O exceeds unity (Φ550 nm=1.38) indicative of dark reactions following the initial photoprocess. DNA photocleavage was observed for 1 (λirr>590 nm), whereas the complex is unreactive in the dark. This feature makes 1 a promising photodynamic therapy agent that does not operate via the production of singlet oxygen, 1O2.

  17. Metamorphic core complex formation by density inversion and lower-crust extrusion.

    PubMed

    Martinez, F; Goodliffe, A M; Taylor, B

    2001-06-21

    Metamorphic core complexes are domal uplifts of metamorphic and plutonic rocks bounded by shear zones that separate them from unmetamorphosed cover rocks. Interpretations of how these features form are varied and controversial, and include models involving extension on low-angle normal faults, plutonic intrusions and flexural rotation of initially high-angle normal faults. The D'Entrecasteaux islands of Papua New Guinea are actively forming metamorphic core complexes located within a continental rift that laterally evolves to sea-floor spreading. The continental rifting is recent (since approximately 6 Myr ago), seismogenic and occurring at a rapid rate ( approximately 25 mm yr-1). Here we present evidence-based on isostatic modelling, geological data and heat-flow measurements-that the D'Entrecasteaux core complexes accommodate extension through the vertical extrusion of ductile lower-crust material, driven by a crustal density inversion. Although buoyant extrusion is accentuated in this region by the geological structure present-which consists of dense ophiolite overlaying less-dense continental crust-this mechanism may be generally applicable to regions where thermal expansion lowers crustal density with depth.

  18. A tetranuclear cadmium(II) complex based on the 2-(quinolin-8-yloxy)acetonitrile ligand.

    PubMed

    Liu, Ming-Liang; Ye, Qiong

    2013-01-01

    The hydrothermal reaction of 2-(quinolin-8-yloxy)acetonitrile and Cd(ClO(4))(2) yielded the noncentrosymmetric coordination complex tetrakis[μ-2-(quinolin-8-yloxy)acetato]tetrakis[μ-2-(quinolin-8-yloxy)acetonitrile]tetracadmium tetrakis(perchlorate) dihydrate, [Cd(4)(C(11)H(8)NO(3))(4)(C(11)H(8)N(2)O)(4)](ClO(4))(4)·2H(2)O. The local coordination environment around the Cd(II) cation can be best described as a capped octahedron defined by two N atoms and five O atoms from three ligands. The Cd(II) cations are linked by the ligands with Cd-O-Cd and Cd-O-C-C-O-Cd bridges, forming tetranuclear units, there being two independent tertranuclear units in the structure. The fourfold rotoinversion centre sits at the centre of each Cd(4) core. The two perchlorate anions in the asymmetric unit are linked by the water molecule through O-H...O hydrogen bonds.

  19. Syntheses, structural characterization, luminescence and optical studies of Ni(II) and Zn(II) complexes containing salophen ligand

    NASA Astrophysics Data System (ADS)

    More, M. S.; Pawal, S. B.; Lolage, S. R.; Chavan, S. S.

    2017-01-01

    Some Ni(II) (1a-d) and Zn(II) (2a-d) salophen complexes were prepared by the treatment of 5-bromosalicylaldehyde, 5-(trimethylsilylethynyl)salicylaldehyde, 5-(4-nitrophenyl)ethynylsalicylaldehyde or 5-(4-methoxyphenyl)ethynylsalicylaldehyde with nickel acetate or zinc acetate followed by addition of 2,3-diamino-5-bromopyridine. All complexes were characterized by elemental analyses, IR, 1H NMR and mass spectral studies. X-ray powder diffraction of representative complexes 1c and 2b and SEM studies of 1b and 2d are used to elucidate the crystal structure and morphology of the complexes. The electrochemical behavior reveals that the redox responses of Ni(II) complexes shifted to more negative potential in order to increase the π-conjugation in the complexes. Room temperature luminescence is observed for all complexes corresponding to π→π* ILCT transition with some MLCT character in DMF and is finely tuned by the degree of extended π-conjugation and variation of the substituent group with different electronic effects in the complexes. The second harmonic generation (SHG) efficiency of the complexes was screened by Kurtz-powder technique indicating that all complexes possesses promising potential for the application as a useful nonlinear optical material.

  20. Synthesis, characterization and DNA binding/cleavage, protein binding and cytotoxicity studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes of aminonaphthoquinone.

    PubMed

    Kosiha, A; Parthiban, C; Elango, Kuppanagounder P

    2017-03-01

    The Co(II), Ni(II), Cu(II) and Zn(II) complexes of an aminonaphthoquinone ligand (L) have been prepared and characterized using analytical and spectral techniques. The structures of L and its Zn(II) complex are confirmed by single crystal X-ray diffraction study. The results indicate that Co(II), Ni(II) and Zn(II) complexes possess tetrahedral geometry while Cu(II) complex exhibits square planar structure. The interaction of L and its complexes with CT-DNA reveal that they could interact with CT-DNA through intercalation. The DNA cleavage studies of the L and its complexes indicate that the Cu(II) and Ni(II) complexes cleave the circular form of the DNA relatively to a greater extent than the other complexes. The results of the interaction of these compounds with bovine serum albumin (BSA) indicate that the complexes exhibit a strong binding to BSA over the L. The in vitro anticancer activities indicate that these compounds exhibit substantial activity against human breast (MCF7) and lung cancer (A549) cell lines. The characteristics of apoptosis in cell morphology have been observed using AO/EB and DAPI staining and the results suggest that an apoptotic mode of cell death with these compounds. The overall results and discussion indicate that coordination of metal ions with the ligand enhances the biological activity.

  1. Metal complexes derived from hydrazoneoxime ligands: V. Spectral and structural studies on diacetylmonoxime n-alkanoylhydrazones and their nickel(II) and copper(II) complexes

    NASA Astrophysics Data System (ADS)

    Salem, Nahed M. H.; El Sayed, Laila; Haase, Wolfgang; Iskander, Magdi F.

    2015-01-01

    A series of diacetylmonoxime n-alkanoylhydrazones (H2Ln, n = 4, 5, 6, 12 and 16) were prepared by the condensation of diacetylmonoxime with the corresponding n-alkanoylhydrazine in ethanol. The X-ray crystal structure of diacetylmonoxime octadecanoyl hydrazone has been solved and its molecular and supramolecular structures have been discussed. Both neutral dinuclear Cu(II) and Ni(II) complexes, [{M(Ln)}2] (M = Cu, Ni and n = 4, 5, 6, 12 and 16) as well as cationic dinuclear Cu(II) complexes, [Cu2(Ln)(HLn)]NO3 (n = 12 and 16) have been also prepared and characterized by elemental analyses, FD- and ESI-mass spectra as well as IR, UV-Vis, 1H NMR, 13C NMR spectra. Variable temperature magnetic susceptibility measurements for dinuclear Cu(II) complexes have been also discussed.

  2. Metal complexes derived from hydrazoneoxime ligands: V. Spectral and structural studies on diacetylmonoxime n-alkanoylhydrazones and their nickel(II) and copper(II) complexes.

    PubMed

    Salem, Nahed M H; El Sayed, Laila; Haase, Wolfgang; Iskander, Magdi F

    2015-01-05

    A series of diacetylmonoxime n-alkanoylhydrazones (H₂L(n), n=4, 5, 6, 12 and 16) were prepared by the condensation of diacetylmonoxime with the corresponding n-alkanoylhydrazine in ethanol. The X-ray crystal structure of diacetylmonoxime octadecanoyl hydrazone has been solved and its molecular and supramolecular structures have been discussed. Both neutral dinuclear Cu(II) and Ni(II) complexes, [{M(L(n))}₂] (M=Cu, Ni and n=4, 5, 6, 12 and 16) as well as cationic dinuclear Cu(II) complexes, [Cu₂(L(n))(HL(n))]NO₃ (n=12 and 16) have been also prepared and characterized by elemental analyses, FD- and ESI-mass spectra as well as IR, UV-Vis, (1)H NMR, (13)C NMR spectra. Variable temperature magnetic susceptibility measurements for dinuclear Cu(II) complexes have been also discussed.

  3. Thermodynamic and kinetic hydricity of ruthenium(II) hydride complexes.

    PubMed

    Matsubara, Yasuo; Fujita, Etsuko; Doherty, Mark D; Muckerman, James T; Creutz, Carol

    2012-09-26

    Despite the fundamental importance of the hydricity of a transition metal hydride (ΔG(H–)°(MH) for the reaction M–H → M+ + H–) in a range of reactions important in catalysis and solar energy storage, ours (J. Am. Chem. Soc.2009, 131, 2794) are the only values reported for water solvent, and there has been no basis for comparison of these with the wider range already determined for acetonitrile solvent, in particular. Accordingly, we have used a variety of approaches to determine hydricity values in acetonitrile of Ru(II) hydride complexes previously studied in water. For [Ru(η(6)-C6Me6)(bpy)H]+ (bpy = 2,2′-bipyridine), we used a thermodynamic cycle based on evaluation of the acidity of [Ru(η(6)-C6Me6)(bpy)H]+ pKa = 22.5 ± 0.1 and the [Ru(η(6)-C6Me6)(bpy)(NCCH3)(1/0)](2+/0) electrochemical potential (−1.22 V vs Fc+/Fc). For [Ru(tpy)(bpy)H]+ (tpy = 2,2′:6′,2″-terpyridine) we utilized organic hydride ion acceptors (A+) of characterized hydricity derived from imidazolium cations and pyridinium cations, and determined K for the hydride transfer reaction, S + MH+ + A+ → M(S)2+ + AH (S = CD3CN, MH+ = [Ru(tpy)(bpy)H]+), by 1H NMR measurements. Equilibration of initially 7 mM solutions was slow--on the time scale of a day or more. When E°(H+/H–) is taken as 79.6 kcal/mol vs Fc+/Fc as a reference, the hydricities of [Ru(η(6)-C6Me6)(bpy)H]+ and [Ru(tpy)(bpy)H]+ were estimated as 54 ± 2 and 39 ± 3 kcal/mol, respectively, in acetonitrile to be compared with the values 31 and 22 kcal/mol, respectively, found for aqueous media. The pKa estimated for [Ru(tpy)(bpy)H]+ in acetonitrile is 32 ± 3. UV–vis spectroscopic studies of [Ru(η(6)-C6Me6)(bpy)]0 and [Ru(tpy)(bpy)]0 indicate that they contain reduced bpy and tpy ligands, respectively. These conclusions are supported by DFT electronic structure results. Comparison of the hydricity values for acetonitrile and water reveals a flattening or compression of the hydricity range upon transferring the

  4. Xenon difluoride induced aryl iodide reductive elimination: a simple access to difluoropalladium(II) complexes.

    PubMed

    Kaspi, Ariela W; Yahav-Levi, Anette; Goldberg, Israel; Vigalok, Arkadi

    2008-01-07

    Palladium(II) aryliodo complexes bearing chelating diphosphine ligands react with XeF2, giving iodoarene and rare palladium(II) difluoro complexes. The reaction is general with regard to the aryl group, with even C6F5-I undergoing facile reductive elimination from a Pd center.

  5. Unraveling a graveyard of core complexes at the 13N segment of the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Schouten, H.; Smith, D. K.

    2006-12-01

    On the west flank of the 13N MAR segment lies a veritable graveyard of core complexes capped by low-angle corrugated detachment surfaces in various stages of evolution [Smith et al. 2006]. The numerous detachment surfaces that cover the seafloor in this region may answer some important questions: Where do core complexes initiate and how regularly? How do they evolve as they are exhumed, get rafted away from the axis, and become extinct? Our goal is to reconstruct the formation and development of the more than 30 core complexes that we observe both on and off axis in this unique region of the Atlantic. Seafloor magnetic anomaly data are essential to decipher the spreading history and to study the effect of repeated core complex formation on the symmetry of spreading. The magnetic anomaly data can be used to estimate the kinematic history of each individual core complex, in particular the age, duration and velocity of its opening, and the distance from the axis that the core complex initiated. The analysis is based on the assumption that for the duration of core complex exhumation, symmetric spreading continues at the magmatic axis, albeit at a reduced rate. We show examples of the application of this analysis to core complexes identified near the MAR. In the first example, we investigate a single core complex on the eastern side of the ridge at 14.7N [Fujiwara et al. 2003]. We use magnetic anomalies on the western side of the ridge to show that a significant reduction of spreading half rate from about 12 km/My to 5 km/My occurs at 1.1 Ma. This we interpret to be the time at which exhumation of the core complex began while the magmatic spreading center did not shut down but remained active at a reduced rate. Simultaneous spreading of a magmatic spreading center and an amagmatic detachment fault has been documented at the TAG segment of the MAR (26 N) [Tivey et al. 2003]. On the eastern side of the ridge we identify a "gap" of about 12 km in the magnetic anomaly

  6. New Ru(II)/Os(II)-polypyridyl complexes for coupling to TiO2 surfaces through acetylacetone functionality and studies on interfacial electron-transfer dynamics.

    PubMed

    Banerjee, Tanmay; Biswas, Abul Kalam; Sahu, Tuhin Subhra; Ganguly, Bishwajit; Das, Amitava; Ghosh, Hirendra Nath

    2014-09-28

    New Ru(ii)- and Os(ii)-polypyridyl complexes have been synthesized with pendant acetylacetone (acac) functionality for anchoring on nanoparticulate TiO2 surfaces with a goal of developing an alternate sensitizer that could be utilized for designing an efficient dye-sensitized solar cell (DSSC). Time-resolved transient absorption spectroscopic studies in the femtosecond time domain have been carried out. The charge recombination rates are observed to be very slow, compared with those for strongly coupled dye molecules having catechol as the anchoring functionality. The results of such studies reveal that electron-injection rates from the metal complex-based LUMO to the conduction band of TiO2 are faster than one would expect for an analogous complex in which the chromophoric core and the anchoring moiety are separated with multiple saturated C-C linkages. Such an observation is rationalized based on computational studies, and a relatively smaller spatial distance between the dye LUMO and the TiO2 surface accounted for this. Results of this study are compared with those for analogous complexes having a gem-dicarboxy group as the anchoring functionality for covalent binding to the TiO2 surface to compare the role of binding functionalities on electron-transfer dynamics.

  7. Carbonic Anhydrase Inhibitors. Part 461 Inhibition of Carbonic Anhydrase Isozymes I, II and IV With Trifluoromethylsulfonamide Derivatives and Their Zinc(II) and Copper(II) Complexes

    PubMed Central

    Mincione, Giovanna; Scozzafava, Andrea

    1997-01-01

    Reaction of aromatic/heterocyclic sulfonamides containing a free amino group with triflic anhydride afforded compounds possessing trifluoromethanesulfonamido moieties in their molecule. The Zn(II) and Cu(II) complexes of these new sulfonamides were prepared and characterized by standard procedures (elemental analysis, spectroscopic, magnetic, thermogravimetric and conductimetric measurements). The new derivatives showed good inhibitory activity against three isozymes of carbonic anhydrase (CA), i.e., CA I, II and IV. PMID:18475762

  8. Water formation in early solar nebula: II-Collapsing cloud core

    NASA Astrophysics Data System (ADS)

    Tornow, C.; Gast, P.; Motschmann, U.; Kupper, S.; Kührt, E.; Pelivan, I.

    2014-08-01

    The formation of water is a repetitive process and depends on the physical conditions in the different stages of the solar nebula and early solar system. Our solar nebula model considers the thermal and chemical evolution of a collapsing globular cloud core. We simulate the collapse with a semi-analytical model which is based on a multi-zone density distribution. This model describes the formation of a central protostellar object surrounded by a disk and a thin outer envelope. It considers an adiabatic equation of state, viscous gas flow and a resistive magnetic field. Due to the low temperatures in the hydrostatic stage of the core, icy layers of water mixed with other molecules build on the dust grains. In the course of the collapse the ice sublimates and drives a complex chemical evolution located in a warm region around the proto-stellar object called hot corino. Moreover, the relatively high temperatures in this region allow the gas phase formation of water together with other molecules. The abundances of the chemical compounds are computed from rate equations solved in a Lagrangian grid. We can show that there was high water density in the early and late accretion zone of the Earth. This water was sublimated from the dust or formed by hot neutral reactions in the gas phase. Thus, according to our collapse model, there were two sources delivering the water incorporated into the Earth.

  9. The Co(II), Ni(II) and Cu(II) complexes with herbicide 2,4-dichlorophenoxyacetic acid - Synthesis and structural studies

    NASA Astrophysics Data System (ADS)

    Drzewiecka-Antonik, Aleksandra; Ferenc, Wiesława; Wolska, Anna; Klepka, Marcin T.; Cristóvão, Beata; Sarzyński, Jan; Rejmak, Paweł; Osypiuk, Dariusz

    2017-01-01

    The Co(II), Ni(II) and Cu(II) complexes with herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) were synthesized and structurally characterized. The geometry of metal-ligand interaction was refined using XAFS and DFT studies. The Co(2,4-D)2·6H2O and Ni(2,4-D)2·4H2O complexes have octahedral geometry with two carboxylate groups of 2,4-D anions and four water molecules in the coordination sphere. The square planar geometry around metal cations formed by the carboxylate groups from two monodentate ligands and two water molecules, is observed for Cu(2,4-D)2·4H2O complex. In the recrystallized Ni(II) complex dinuclear 'Chinese lantern' structures with bridging carboxylate groups of 2,4-D were observed.

  10. Simulation Based Optimization of Complex Monolithic Composite Structures Using Cellular Core Technology

    NASA Astrophysics Data System (ADS)

    Hickmott, Curtis W.

    Cellular core tooling is a new technology which has the capability to manufacture complex integrated monolithic composite structures. This novel tooling method utilizes thermoplastic cellular cores as inner tooling. The semi-rigid nature of the cellular cores makes them convenient for lay-up, and under autoclave temperature and pressure they soften and expand providing uniform compaction on all surfaces including internal features such as ribs and spar tubes. This process has the capability of developing fully optimized aerospace structures by reducing or eliminating assembly using fasteners or bonded joints. The technology is studied in the context of evaluating its capabilities, advantages, and limitations in developing high quality structures. The complex nature of these parts has led to development of a model using the Finite Element Analysis (FEA) software Abaqus and the plug-in COMPRO Common Component Architecture (CCA) provided by Convergent Manufacturing Technologies. This model utilizes a "virtual autoclave" technique to simulate temperature profiles, resin flow paths, and ultimately deformation from residual stress. A model has been developed simulating the temperature profile during curing of composite parts made with the cellular core technology. While modeling of composites has been performed in the past, this project will look to take this existing knowledge and apply it to this new manufacturing method capable of building more complex parts and develop a model designed specifically for building large, complex components with a high degree of accuracy. The model development has been carried out in conjunction with experimental validation. A double box beam structure was chosen for analysis to determine the effects of the technology on internal ribs and joints. Double box beams were manufactured and sectioned into T-joints for characterization. Mechanical behavior of T-joints was performed using the T-joint pull-off test and compared to traditional

  11. Copper(II), nickel(II) and zinc(II) complexes of the N-terminal nonapeptide fragment of amyloid-β and its derivatives.

    PubMed

    Grenács, Ágnes; Sóvágó, Imre

    2014-10-01

    Copper(II), nickel(II) and zinc(II) complexes of the nonapeptide fragment of amyloid-β Aβ(1-9) (NH2-DAEFRHDSG-NH2) and its two derivatives: NH2-DAAAAHAAA-NH2 and NH2-DAAAAAHAA-NH2 have been studied by potentiometric, UV-visible and CD spectroscopic methods. The results reveal the primary role of the amino terminus of peptides in copper(II) and nickel(II) binding. The formation of dinuclear complexes was also possible in the copper(II) containing systems but only the first six amino acids from the amino terminus were involved in metal binding in the physiologically relevant pH range. The coordination chemistry of the two alanine mutated peptides is almost the same as that of the native nonapeptide, but the thermodynamic stability of the copper(II) complexes of the mutants is significantly reduced. This difference probably comes from the secondary interactions of the polar side chains of Asp, Glu, Ser and Arg residues present in the native peptide. Moreover, this difference reveals that the amino acid sequence of the N-terminal domains of amyloid peptides is especially well suited for the complexation with copper(II) ions.

  12. Synthesis, antimicrobial activity, structural and spectral characterization and DFT calculations of Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile.

    PubMed

    Mohamed, Tarek A; Shaaban, Ibrahim A; Farag, Rabei S; Zoghaib, Wajdi M; Afifi, Mahmoud S

    2015-01-25

    Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile (APC) have been synthesized and characterized using elemental analysis, magnetic susceptibility, mass spectrometry, infrared (4000-200 cm(-1)), UV-Visible (200-1100 nm), (1)H NMR and ESR spectroscopy as well as TGA analysis. The molar conductance measurements in DMSO imply non-electrolytic complexes, formulated as [M(APC)2Cl2] where M=Co(II), Ni(II), Cu(II) and Pd(II). The infrared spectra of Co(II), Ni(II) and Cu(II) complexes indicate a bidentate type of bonding for APC through the exocyclic amino and adjacent pyrimidine nitrogen as donors whereas APC coordinated to Pd(II) ion as a monodentated ligand via a pyrimidine nitrogen donor. The magnetic measurements and the electronic absorption spectra support distorted octahedral geometries for Co(II), Ni(II) and Cu(II) complexes however a square planar complex was favored for the Pd(II) complex (C2h skeleton symmetry). In addition, we carried out B3LYP and ω-B97XD geometry optimization at 6-31G(d) basis set except for Pd(II) where we implemented LanL2DZ/6-31G(d) combined basis set. The computational results favor all trans geometrical isomers where amino N, pyrimidine N and Cl are trans to each other (structure 1). Finally, APC and its divalent metal ion complexes were screened for their antibacterial activity, and the synthesized complexes were found to be more potent antimicrobial agents than APC against one or more microbial species.

  13. Synthesis, antimicrobial activity, structural and spectral characterization and DFT calculations of Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile

    NASA Astrophysics Data System (ADS)

    Mohamed, Tarek A.; Shaaban, Ibrahim A.; Farag, Rabei S.; Zoghaib, Wajdi M.; Afifi, Mahmoud S.

    2015-01-01

    Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile (APC) have been synthesized and characterized using elemental analysis, magnetic susceptibility, mass spectrometry, infrared (4000-200 cm-1), UV-Visible (200-1100 nm), 1H NMR and ESR spectroscopy as well as TGA analysis. The molar conductance measurements in DMSO imply non-electrolytic complexes, formulated as [M(APC)2Cl2] where M = Co(II), Ni(II), Cu(II) and Pd(II). The infrared spectra of Co(II), Ni(II) and Cu(II) complexes indicate a bidentate type of bonding for APC through the exocyclic amino and adjacent pyrimidine nitrogen as donors whereas APC coordinated to Pd(II) ion as a monodentated ligand via a pyrimidine nitrogen donor. The magnetic measurements and the electronic absorption spectra support distorted octahedral geometries for Co(II), Ni(II) and Cu(II) complexes however a square planar complex was favored for the Pd(II) complex (C2h skeleton symmetry). In addition, we carried out B3LYP and ω-B97XD geometry optimization at 6-31G(d) basis set except for Pd(II) where we implemented LanL2DZ/6-31G(d) combined basis set. The computational results favor all trans geometrical isomers where amino N, pyrimidine N and Cl are trans to each other (structure 1). Finally, APC and its divalent metal ion complexes were screened for their antibacterial activity, and the synthesized complexes were found to be more potent antimicrobial agents than APC against one or more microbial species.

  14. Core size determination and structural characterization of intravenous iron complexes by cryogenic transmission electron microscopy.

    PubMed

    Wu, Yong; Petrochenko, Peter; Chen, Lynn; Wong, Sook Yee; Absar, Mohammad; Choi, Stephanie; Zheng, Jiwen

    2016-05-30

    Understanding physicochemical properties of intravenous (IV) iron drug products is essential to ensure the manufacturing process is consistent and streamlined. The history of physicochemical characterization of IV iron complex formulations stretches over several decades, with disparities in iron core size and particle morphology as the major source of debate. One of the main reasons for this controversy is room temperature sample preparation artifacts, which affect accurate determination of size, shape and agglomeration/aggregation of nanoscale iron particles. The present study is first to report the ultra-fine iron core structures of four IV iron complex formulations, sodium ferric gluconate, iron sucrose, low molecular weight iron dextran and ferumoxytol, using a cryogenic transmission electron microscopy (cryo-TEM) preservation technique, as opposed to the conventional room temperature (RT-TEM) technique. Our results show that room temperature preparation causes nanoparticle aggregation and deformation, while cryo-TEM preserves IV iron colloidal suspension in their native frozen-hydrated and undiluted state. In contrast to the current consensus in literature, all four IV iron colloids exhibit a similar morphology of their iron oxide cores with a spherical shape, narrow size distribution and an average size of 2nm. Moreover, out of the four tested formulations, ferumoxytol exhibits a cluster-like community of several iron carbohydrate particles which likely accounts for its large hydrodynamic size of 25nm, measured with dynamic light scattering. Our findings outline a suitable method for identifying colloidal nanoparticle core size in the native state, which is increasingly important for manufacturing and design control of complex drug formulations, such as IV iron drug products.

  15. Docking of ethanamine Schiff base imines & metal (II) complexes, cytotoxicity & DNA interaction studies

    NASA Astrophysics Data System (ADS)

    Sujarani, S.; Ramu, A.

    2015-01-01

    The present study deals with a series of biologically and stereo chemically important novel transition metal (II) Schiff base chelates. The Cu (II), Co (II), Mn (II) and Ni (II) ions containing complexes were synthesized by using diphenylethanamine and 2-hydroxy/2, 4-dihydroxy/2-hydroxy-4-methoxybenzaldehydes. The synthesized complexes were characterized using micro analytical, IR, NMR, ESI-Mass, UV-Visible, cyclic voltammetry and the EPR spectroscopic techniques. The spectral data evidenced the action of ligands as a neutral bidentate Schiff bases, coordinating through azomethine nitrogen and oxygen atom of hydroxyl group. The interaction studies revealed the groove binding nature of complexes with CT-DNA. The ligand and synthesized metal complexes showed cytotoxicity against cancerous cells. The strong binding affinity of the imine and metal complexes was also confirmed by molecular docking studies.

  16. North and equatorial Pacific Ocean circulation in the CORE-II hindcast simulations

    NASA Astrophysics Data System (ADS)

    Tseng, Yu-heng; Lin, Hongyang; Chen, Han-ching; Thompson, Keith; Bentsen, Mats; Böning, Claus W.; Bozec, Alexandra; Cassou, Christophe; Chassignet, Eric; Chow, Chun Hoe; Danabasoglu, Gokhan; Danilov, Sergey; Farneti, Riccardo; Fogli, Pier Giuseppe; Fujii, Yosuke; Griffies, Stephen M.; Ilicak, Mehmet; Jung, Thomas; Masina, Simona; Navarra, Antonio; Patara, Lavinia; Samuels, Bonita L.; Scheinert, Markus; Sidorenko, Dmitry; Sui, Chung-Hsiung; Tsujino, Hiroyuki; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang; Yeager, Steve G.

    2016-08-01

    We evaluate the mean circulation patterns, water mass distributions, and tropical dynamics of the North and Equatorial Pacific Ocean based on a suite of global ocean-sea ice simulations driven by the CORE-II atmospheric forcing from 1963-2007. The first three moments (mean, standard deviation and skewness) of sea surface height and surface temperature variability are assessed against observations. Large discrepancies are found in the variance and skewness of sea surface height and in the skewness of sea surface temperature. Comparing with the observation, most models underestimate the Kuroshio transport in the Asian Marginal seas due to the missing influence of the unresolved western boundary current and meso-scale eddies. In terms of the Mixed Layer Depths (MLDs) in the North Pacific, the two observed maxima associated with Subtropical Mode Water and Central Mode Water formation coalesce into a large pool of deep MLDs in all participating models, but another local maximum associated with the formation of Eastern Subtropical Mode Water can be found in all models with different magnitudes. The main model bias of deep MLDs results from excessive Subtropical Mode Water formation due to inaccurate representation of the Kuroshio separation and of the associated excessively warm and salty Kuroshio water. Further water mass analysis shows that the North Pacific Intermediate Water can penetrate southward in most models, but its distribution greatly varies among models depending not only on grid resolution and vertical coordinate but also on the model dynamics. All simulations show overall similar large scale tropical current system, but with differences in the structures of the Equatorial Undercurrent. We also confirm the key role of the meridional gradient of the wind stress curl in driving the equatorial transport, leading to a generally weak North Equatorial Counter Current in all models due to inaccurate CORE-II equatorial wind fields. Most models show a larger

  17. Spectroscopic and thermal degradation behavior of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes with thiopental sodium anesthesia drug

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.

    2013-04-01

    A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized with thiopental sodium anesthesia drug. The elemental analyses of the complexes are confined to stoichiometry of the formulas [M(TPL)3]ṡnH2O (M = Cr(III) or Fe(III); n = 6 or 5), [M(TPL)2(H2O)2]ṡnH2O (M = Mn(II), Co(II) or Ni(II); n = 0 or 4), and [M(TPL)2] (M = Cu(II) or Zn(II); n = 2 or 0) respectively, where TPL is thiopental chelating agent. Structures have been discussed and suggested upon elemental analyses, infrared, Raman, electronic, electron spin resonance, 1H NMR spectral data and magnetic studies. The X-ray powder diffraction (XRD) was performed of metal complexes. The XRD patterns indicate crystalline nature for the complexes. The measured low molar conductance values in dimethylsulfoxide indicate that the complexes are non-electrolyte nature. Spectroscopic discussion refer that coordination take place through three types: Cdbnd N (pyrimidine moiety) nitrogen and C2sbnd S (2-thiolate group) for Cr(III), Mn(II) and Fe(III), C6dbnd O (amido group) oxygen and C2sbnd S (2-thiolate group) for Co(II) and Ni(II), and Cu(II) and Zn(II) ions coordinated via Cdbnd N (pyrimidine moiety) nitrogen, C2dbnd S (2-thiolate group) and C6dbnd O (amido group) oxygen, respectively. The thermal behavior (TG/DTG/DTA) of the complexes was studied and kinetic parameters were determined by Horowitz-Metzger and Coats-Redfern methods. The thiopental and its complexes have been screened for their antimicrobial (G+ and G-) bacteria (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa) and fungi (Aspergillus flavus and Candida albicans) activities by minimum inhibitory concentration (MIC) method.

  18. The Electronic Structure of CdSe/CdS Core/Shell Seeded Nanorods: Type-I or Quasi-Type-II?

    PubMed Central

    2013-01-01

    The electronic structure of CdSe/CdS core/shell seeded nanorods of experimentally relevant size is studied using a combination of molecular dynamics and semiempirical pseudopotential techniques with the aim to address the transition from type-I to a quasi-type-II band alignment. The hole is found to be localized in the core region regardless of its size. The overlap of the electron density with the core region depends markedly on the size of the CdSe core. For small cores, we observe little overlap, consistent with type-II behavior. For large cores, significant core-overlap of a number of excitonic states can lead to type-I behavior. When electron–hole interactions are taken into account, the core-overlap is further increased. Our calculations indicate that the observed transition from type-II to type-I is largely due to simple volume effects and not to band alignment. PMID:24215466

  19. Synthesis, DNA recognition and cleavage studies of novel tetrapeptide complexes, Cu(II)/Zn(II)-Ala-Pro-Ala-Pro

    NASA Astrophysics Data System (ADS)

    Arjmand, Farukh; Jamsheera, A.; Mohapatra, D. K.

    2013-05-01

    New tetrapeptide complexes Cu(II)·Ala-Pro-Ala-Pro (1) and Zn(II)·Ala-Pro-Ala-Pro (2) were synthesized from the reaction of tetrapeptide, Ala-Pro-Ala-Pro and CuCl2/ZnCl2 and were thoroughly characterized by elemental analysis, IR,1H and 13C NMR (in case of 2), ESI-MS, UV and molar conductance measurements. The solution stability study was carried out employing UV-vis absorption titrations over a broad range of pH which suggested the stability of the complexes in solution. In vitro interaction of complexes 1 and 2 with CT-DNA was studied employing UV-vis, fluorescence, circular dichroic and viscometry studies. To throw insight into molecular binding event at the target site, UV-vis titrations of 1 and 2 with mononucleotides of interest viz.; 5'-GMP and 5'-TMP were carried out. Cleavage activity of the complexes with pBR322 plasmid DNA was evaluated by agarose gel electrophoresis and, the electrophoresis pattern demonstrated that both the complexes 1 and 2 are efficient cleavage agents. Further, the Cu(II) complex displayed efficient oxidative cleavage of supercoiled DNA while various reactive oxygen species are responsible for the cleavage in Zn(II) complex.

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

    PubMed

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

    2011-06-20

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

  1. Spectroscopic, magnetic and thermal studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes of 3-acetylcoumarin-isonicotinoylhydrazone and their antimicrobial and anti-tubercular activity evaluation

    NASA Astrophysics Data System (ADS)

    Hunoor, Rekha S.; Patil, Basavaraj R.; Badiger, Dayananda S.; Vadavi, Ramesh S.; Gudasi, Kalagouda B.; Chandrashekhar, V. M.; Muchchandi, I. S.

    2010-11-01

    Co(II), Ni(II), Cu(II) and Zn(II) complexes with a new heterocyclic Schiff base derived by the condensation of isonicotinoylhydrazide and 3-acetylcoumarin have been synthesized. 1H, 13C and 2D HETCOR NMR analyses confirm the formation of title compound and existence of the same in two isomeric forms. The metal complexes were characterized on the basis of various spectroscopic techniques like electronic, EPR, IR, 1H and 13C NMR studies, elemental analysis, magnetic properties and thermogravimetric analysis, and also by the aid of molar conductivity measurements. It is found that the Schiff base behaves as a monobasic tridentate ligand coordinating in the imidol form with 1:1 metal to ligand stoichiometry. Trigonal bipyramidal geometry has been assigned for Ni(II) and Cu(II) complexes, while tetrahedral for Co(II) and Zn(II) complexes. The compounds were subjected to antimicrobial and anti-tubercular activity screening using serial broth dilution method and Minimum Inhibitory Concentration (MIC) is determined. Zn(II) complex has shown significant antifungal activity with an MIC of 6.25 μg/mL while Cu(II) complex is noticeable for antibacterial activity at the same concentration. Anti-TB activity of the ligand has enhanced on complexation with Co(II) and Ni(II) ions.

  2. Organic light-emitting diodes containing fluorinated asymmetrical europium cored beta-diketone complexes

    NASA Astrophysics Data System (ADS)

    Phelan, Gregory D.; Carlson, Brenden; Jiang, Xuezhong; Jen, Alex K. Y.; Dalton, Larry R.

    2003-03-01

    Novel luminescent materials based on europium-cored complexes have been synthesized and incorporated into light emitting diodes using poly (N-vinyl-carbazole) and poly (vinyl naphthalene) blends as doping hosts. The complexes consists of fluorinated β-diketone ligands chelated to europium. Excitation of the ligands and efficient transfer of energy from the excited ligands to the metal core results in the emission of optically pure red light. The ligands were designed such that they include a polycyclic aromatic compound, phenanthrene, and a second substituent to improve processibility. Phenanthrene is used to so that the ligand energy will match with the energy of the metal center. Partially fluorinated substituents were also used to help improve the efficiency and charge transfer capability of the resulting metal complex. The complex consisted of one equivalent of europium and three equivalents of the ligand. One equivalent of either 1,10-phenanthroline or 4,7-diphenyl-1,10-phenanthroline was also chelated to enhance the stability of the complex. Double and triple layer devices were synthesized with the configuration of ITO/BTPD-PFCB/Europium complex in a polymer blend/Ca/Ag for the double layer device and ITO/BTPD-PFCB/Europium complex in a polymer blend/PBD/Ca/Ag for the triple layer device. The double layer devices made with a polymer blend of PVN outperformed the devices made from PVK as the emission bands of the PVN better match the absorption bands of the ligands. A maximum brightness of 178 cd/m2 with a maximum external quantum efficiency of 0.45% was measured for the double layer device.

  3. New dinuclear copper(II) and zinc(II) complexes for the investigation of sugar-metal ion interactions.

    PubMed

    Bera, Manindranath; Patra, Ayan

    2011-10-18

    We have studied the binding interactions of biologically important carbohydrates (D-glucose, D-xylose and D-mannose) with the newly synthesized five-coordinate dinuclear copper(II) complex, [Cu(2)(hpnbpda)(μ-OAc)] (1) and zinc(II) complex, [Zn(2)(hpnbpda)(μ-OAc)] (2) [H(3)hpnbpda=N,N'-bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-N,N'-diacetic acid] in aqueous alkaline solution. The complexes 1 and 2 are fully characterized both in solid and solution using different analytical techniques. A geometrical optimization was made of the ligand H(3)hpnbpda and the complexes 1 and 2 by molecular mechanics (MM+) method in order to establish the stable conformations. All carbohydrates bind to the metal complexes in a 1:1 molar ratio. The binding events have been investigated by a combined approach of FTIR, UV-vis and (13)C NMR spectroscopic techniques. UV-vis spectra indicate a significant blue shift of the absorption maximum of complex 1 during carbohydrate coordination highlighting the sugar binding ability of complex 1. The apparent binding constants of the substrate-bound copper(II) complexes have been determined from the UV-vis titration experiments. The binding ability and mode of binding of these sugar substrates with complex 2 are indicated by their characteristic coordination induced shift (CIS) values in (13)C NMR spectra for carbon atoms C1, C2, and C3 of sugar substrates.

  4. FANCM of the Fanconi anemia core complex is required for both monoubiquitination and DNA repair.

    PubMed

    Xue, Yutong; Li, Yongjiang; Guo, Rong; Ling, Chen; Wang, Weidong

    2008-06-01

    In response to DNA damage, the Fanconi anemia (FA) core complex functions as a signaling machine for monoubiquitination of FANCD2 and FANCI. It remains unclear whether this complex can also participate in subsequent DNA repair. We have shown previously that the FANCM constituent of the complex contains a highly conserved helicase domain and an associated ATP-dependent DNA translocase activity. Here we show that FANCM also possesses an ATP-independent binding activity and an ATP-dependent bi-directional branch-point translocation activity on a synthetic four-way junction DNA, which mimics intermediates generated during homologous recombination or at stalled replication forks. Using an siRNA-based complementation system, we found that the ATP-dependent activities of FANCM are required for cellular resistance to a DNA-crosslinking drug, mitomycin C, but not for the monoubiquitination of FANCD2 and FANCI. In contrast, monoubiquitination requires the entire helicase domain of FANCM, which has both ATP dependent and independent activities. These data are consistent with participation of FANCM and its associated FA core complex in the FA pathway at both signaling through monoubiquitination and the ensuing DNA repair.

  5. Synthesis, characterization and quantum chemical ab initio calculations of new dimeric aminocyclodiphosph(V)azane and its Co(II), Ni(II) and Cu(II) complexes.

    PubMed

    Alaghaz, Abdel-Nasser M A; Al-Sehemi, Abdullah G; El-Gogary, Tarek M

    2012-09-01

    The complexes of type [M(2)LCl(2)] in which M=Co(II), Ni(II) and Cu(II) ions and L are 1,3-o-pyridyl-2,4-dioxo-2',4'-bis(3-benzo[d]thiazol-2-yl-2-iminothiophene) cyclodiphosph(V)azane, were prepared and their structures were characterized by different physical techniques (IR, UV-Vis, (1)H NMR, (31)P NMR, mass, TGA, DTA, XRD, SEM, magnetic moment and electrical conductance measurements). Ab initio calculations at the level of DFT B3LYP/6-31G(d) were utilized to find the optimum geometry of the ligand. Spectral characterization of the ligand was simulated using DT-DFT method. Infrared spectra of the complexes indicate deprotonation and coordination of the imine NH. It also confirms that nitrogen atoms of the pyridine group and thiazole group contribute to the complexation. NBO natural charges were computed and discussed in the light of coordination centers. Electronic spectra and magnetic susceptibility measurements as well as quantum chemical calculations reveal square planar geometry for Cu(II) and Ni(II) complexes and tetrahedral geometry for Co(II) complex. The elemental analyses and mass spectral data have justified the M(2)LCl(2) composition of complexes.

  6. Differential susceptibility of mitochondrial complex II to inhibition by oxaloacetate in brain and heart.

    PubMed

    Stepanova, Anna; Shurubor, Yevgeniya; Valsecchi, Federica; Manfredi, Giovanni; Galkin, Alexander

    2016-09-01

    Mitochondrial Complex II is a key mitochondrial enzyme connecting the tricarboxylic acid (TCA) cycle and the electron transport chain. Studies of complex II are clinically important since new roles for this enzyme have recently emerged in cell signalling, cancer biology, immune response and neurodegeneration. Oxaloacetate (OAA) is an intermediate of the TCA cycle and at the same time is an inhibitor of complex II with high affinity (Kd~10(-8)M). Whether or not OAA inhibition of complex II is a physiologically relevant process is a significant, but still controversial topic. We found that complex II from mouse heart and brain tissue has similar affinity to OAA and that only a fraction of the enzyme in isolated mitochondrial membranes (30.2±6.0% and 56.4±5.6% in the heart and brain, respectively) is in the free, active form. Since OAA could bind to complex II during isolation, we established a novel approach to deplete OAA in the homogenates at the early stages of isolation. In heart, this treatment significantly increased the fraction of free enzyme, indicating that OAA binds to complex II during isolation. In brain the OAA-depleting system did not significantly change the amount of free enzyme, indicating that a large fraction of complex II is already in the OAA-bound inactive form. Furthermore, short-term ischemia resulted in a dramatic decline of OAA in tissues, but it did not change the amount of free complex II. Our data show that in brain OAA is an endogenous effector of complex II, potentially capable of modulating the activity of the enzyme.

  7. Synthesis, spectroscopic characterization, molecular modeling and antimicrobial activities of Mn(II), Co(II), Ni(II), Cu(II) complexes containing the tetradentate aza Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Ruchi

    2013-02-01

    Mn(II), Co(II), Ni(II), and Cu(II) complexes with a tetradentate macrocyclic ligand [1.2.5.6tetraoxo-3,4,7,8tetraaza-(1,2,3,4,5,6,7,8)tetrabenzene(L)] were synthesized and characterized by elemental analysis, molar conductance measurements, mass, nmr, i.r., electronic and e.p.r. spectral studies. All the complexes are non electrolytes in nature and may be formulated as [M(L)X2] [where, M = Mn(II), Co(II), Ni(II), Cu(II) and X = Cl-, CH3COO-]. On the basis of i.r., electronic and e.p.r. spectral studies a distorted octahedral geometry has been assigned for all complexes. The antimicrobial activities and LD50 values of the ligand and its complexes, as growth inhibiting agents, have been screened in vitro against two different species of bacteria and plant pathogenic fungi.

  8. Synthesis, crystal structure and magnetic properties of a novel copper(II) complex with sulfoisophthalic acid

    NASA Astrophysics Data System (ADS)

    Kurc, Teresa; Videnova-Adrabinska, Veneta; Turowska-Tyrk, Ilona; Duczmal, Marek; Jerzykiewicz, Maria

    2013-12-01

    A new Cu(II) complex, [Cu2(μ2-OH2)2(HSIP)2(H2O)6] (H3SIP = 5-sulfoisophthalic acid), has been synthesized and characterized by single crystal X-ray diffraction, EPR spectroscopy (X- (9.5 GHz) and Q-band (35 GHz)) and magnetic measurements. The solid state structure of the complex consists of coordination dimers [Cu2(μ2-OH2)2(HSIP)2(H2O)6] which are hydrogen bonded into 3D network. The neighbouring metal ions form a rare example of centrosymetric dinuclear core [Cu2(μ2-OH2)2] with equatorial - axial positions of the bridging ligands. The coordination dimers are organized into inorganic monolayers via water-sulfonate hydrogen bond intractions, and further linked in 3D structure via carboxylic-carboxylic hydrogen bond intractions. The magnetic properties and EPR spectra are discussed in terms of crystal structure features. The X- and Q-band EPR spectra exhibit fine structure signals due to S = 1 and the simulated parameters indicate small zero field splitting parameter Dexp (-0.035 cm-1) dominated by Ddip (-0.031 cm-1). A usually forbidden ΔMs = 2 line of lower intensity is observed in the half field region at about 150 mT. The susceptibility data have been analyzed using a spin-ladder model with both ferromagnetic (rungs) and antiferromagnetic (legs) coupling.

  9. The Ikaria high-temperature Metamorphic Core Complex (Cyclades, Greece): Geometry, kinematics and thermal structure

    NASA Astrophysics Data System (ADS)

    Beaudoin, Alexandre; Augier, Romain; Laurent, Valentin; Jolivet, Laurent; Lahfid, Abdeltif; Bosse, Valérie; Arbaret, Laurent; Rabillard, Aurélien; Menant, Armel

    2015-12-01

    This work attempted at clarifying the structure of Ikaria using primarily intensive geological mapping combined with structural analysis and a geothermometry approach of Raman spectrometry of carbonaceous material. Foliation over the whole island defines a structural dome cored by high-grade to partially molten rocks. Its exhumation was completed by two top-to-the-N ductile extensional shear zones, operating in the ductile and then the brittle fields, through a single extensional event coeval with progressive strain localization. The thermal structure of the dome with regard to position of ductile shear zones was retrieved using the Raman spectroscopy of carbonaceous material. Peak-metamorphic temperatures range from 390 °C in the upper parts of the structure down to 625 °C in the core of the dome in the vicinity of migmatites and S-type granite. Pioneer in situ U-Th-Pb analyses on monazite performed on the leucosome parts of these rock yielded a 15.7 ± 0.2 Ma age. Ikaria Island thus completes the series of Miocene migmatite-cored Metamorphic Core Complex in the central part of the Aegean domain where a genuine high-temperature zone can be defined as the central Aegean HT zone. There, the extreme stretching of the continental crust is associated with dominantly top-to-the-N kinematics.

  10. Sulfur containing platinum(II) complexes with N-heterocyclic carbene ligands obtained by reactions of a hydrosulfido complex.

    PubMed

    Maeda, Yuri; Hashimoto, Hideki; Nishioka, Takanori

    2012-10-21

    A hydrosulfido platinum(ii) complex with a chelated N-heterocyclic carbene (NHC) ligand was oxidised with O(2) in the presence of excess hydrogen sulfide, to give a linear tetrasulfido complex, and without hydrogen sulfide, to give a thiosulfato-bridged dinuclear complex. The hydrosulfido complex also reacted with an acetato complex containing the chelating NHC platinum unit to afford a trinuclear platinum complex with two triply bridging sulfido ligands showing an equilibrium in solution between two isomers based on the arrangement of the chelating NHC ligands.

  11. Pyrrolidine dithiocarbamate-zinc(II) and -copper(II) complexes induce apoptosis in tumor cells by inhibiting the proteasomal activity

    SciTech Connect

    Milacic, Vesna; Chen Di; Giovagnini, Lorena; Diez, Alejandro; Fregona, Dolores; Dou, Q. Ping

    2008-08-15

    Zinc and copper are trace elements essential for proper folding, stabilization and catalytic activity of many metalloenzymes in living organisms. However, disturbed zinc and copper homeostasis is reported in many types of cancer. We have previously demonstrated that copper complexes induced proteasome inhibition and apoptosis in cultured human cancer cells. In the current study we hypothesized that zinc complexes could also inhibit the proteasomal chymotrypsin-like activity responsible for subsequent apoptosis induction. We first showed that zinc(II) chloride was able to inhibit the chymotrypsin-like activity of a purified 20S proteasome with an IC{sub 50} value of 13.8 {mu}M, which was less potent than copper(II) chloride (IC{sub 50} 5.3 {mu}M). We then compared the potencies of a pyrrolidine dithiocarbamate (PyDT)-zinc(II) complex and a PyDT-copper(II) complex to inhibit cellular proteasomal activity, suppress proliferation and induce apoptosis in various human breast and prostate cancer cell lines. Consistently, zinc complex was less potent than copper complex in inhibiting the proteasome and inducing apoptosis. Additionally, zinc and copper complexes appear to use somewhat different mechanisms to kill tumor cells. Zinc complexes were able to activate calpain-, but not caspase-3-dependent pathway, while copper complexes were able to induce activation of both proteases. Furthermore, the potencies of these PyDT-metal complexes depend on the nature of metals and also on the ratio of PyDT to the metal ion within the complex, which probably affects their stability and availability for interacting with and inhibiting the proteasome in tumor cells.

  12. Synthesis, characterization, in vitro antimicrobial and DNA cleavage studies of Co(II), Ni(II) and Cu(II) complexes with ONOO donor coumarin Schiff bases

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Unki, Shrishila N.; Kulkarni, Ajaykumar D.; Naik, Vinod H.; Badami, Prema S.

    2011-01-01

    A series of Co(II), Ni(II) and Cu(II) complexes have been synthesized with Schiff bases derived from 2-hydroxy-1-naphthaldehyde and 2-oxo-2H-chromene-3-carbohydrazide/6-bromo-2-oxo-2H-chromene-3-carbohydrazide. The chelation of the complexes has been proposed in the light of analytical, spectral (IR, UV-Vis, 1H NMR, ESR, FAB-mass and fluorescence), magnetic and thermal studies. The measured molar conductance values indicate that, the complexes are non-electrolytic in nature. The redox behavior of the complexes was investigated with electrochemical method by using cyclic voltammetry. The Schiff bases and their metal complexes have been screened for their in vitro antibacterial ( Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal activities ( Candida albicans, Cladosporium and Aspergillus niger) by MIC method. The DNA cleavage is studied by agarose gel electrophoresis method.

  13. Fluoridonitrosyl complexes of technetium(I) and technetium(II). Synthesis, characterization, reactions, and DFT calculations.

    PubMed

    Balasekaran, Samundeeswari Mariappan; Spandl, Johann; Hagenbach, Adelheid; Köhler, Klaus; Drees, Markus; Abram, Ulrich

    2014-05-19

    A mixture of [Tc(NO)F5](2-) and [Tc(NO)(NH3)4F](+) is formed during the reaction of pertechnetate with acetohydroxamic acid (Haha) in aqueous HF. The blue pentafluoridonitrosyltechnetate(II) has been isolated in crystalline form as potassium and rubidium salts, while the orange-red ammine complex crystallizes as bifluoride or PF6(-) salts. Reactions of [Tc(NO)F5](2-) salts with HCl give the corresponding [Tc(NO)Cl4/5](-/2-) complexes, while reflux in neat pyridine (py) results in the formation of the technetium(I) cation [Tc(NO)(py)4F](+), which can be crystallized as hexafluoridophosphate. The same compound can be synthesized directly from pertechnetate, Haha, HF, and py or by a ligand-exchange procedure starting from [Tc(NO)(NH3)4F](HF2). The technetium(I) cation [Tc(NO)(NH3)4F](+) can be oxidized electrochemically or by the reaction with Ce(SO4)2 to give the corresponding Tc(II) compound [Tc(NO)(NH3)4F](2+). The fluorido ligand in [Tc(NO)(NH3)4F](+) can be replaced by CF3COO(-), leaving the "[Tc(NO)(NH3)4](2+) core" untouched. The experimental results are confirmed by density functional theory calculations on [Tc(NO)F5](2-), [Tc(NO)(py)4F](+), [Tc(NO)(NH3)4F](+), and [Tc(NO)(NH3)4F](2+).

  14. Synthesis and characterization of perchlorato bridged Cu2IIZnII heterotrinuclear complexes derived from succinoyldihydrazones

    NASA Astrophysics Data System (ADS)

    Borthakur, Rosmita; Kumar, Arvind; Shangpung, Sankey; Lal, Ram A.

    2015-03-01

    In the present paper three new heterotrimetallic Cu(II)-Zn(II)-Cu(II) complexes have been synthesized and characterized by analytical and spectroscopic studies. The molar conductance values for the complexes fall in the region 1.2-1.7 Ω-1 cm2 mol-1 in DMSO solution indicating that all of the complexes are non-electrolyte. The dihydrazone ligand is present in enol form in all of the complexes. Both the copper centres have distorted square pyramidal stereochemistry in all of the complexes while the zinc centre in all hetero metal complexes has octahedral stereochemistry. The EPR parameters of the complexes indicate that the copper centre has dx2-y2 orbital as the ground state. The electron transfer reactions of the complexes have been investigated by cyclic voltammetry.

  15. β2-Glycoprotein I/HLA class II complexes are novel autoantigens in antiphospholipid syndrome.

    PubMed

    Tanimura, Kenji; Jin, Hui; Suenaga, Tadahiro; Morikami, Satoko; Arase, Noriko; Kishida, Kazuki; Hirayasu, Kouyuki; Kohyama, Masako; Ebina, Yasuhiko; Yasuda, Shinsuke; Horita, Tetsuya; Takasugi, Kiyoshi; Ohmura, Koichiro; Yamamoto, Ken; Katayama, Ichiro; Sasazuki, Takehiko; Lanier, Lewis L; Atsumi, Tatsuya; Yamada, Hideto; Arase, Hisashi

    2015-04-30

    Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by thrombosis and/or pregnancy complications. β2-glycoprotein I (β2GPI) complexed with phospholipid is recognized as a major target for autoantibodies in APS; however, less than half the patients with clinical manifestations of APS possess autoantibodies against the complexes. Therefore, the range of autoantigens involved in APS remains unclear. Recently, we found that human leukocyte antigen (HLA) class II molecules transport misfolded cellular proteins to the cell surface via association with their peptide-binding grooves. Furthermore, immunoglobulin G heavy chain/HLA class II complexes were specific targets for autoantibodies in rheumatoid arthritis. Here, we demonstrate that intact β2GPI, not peptide, forms a complex with HLA class II molecules. Strikingly, 100 (83.3%) of the 120 APS patients analyzed, including those whose antiphospholipid antibody titers were within normal range, possessed autoantibodies that recognize β2GPI/HLA class II complexes in the absence of phospholipids. In situ association between β2GPI and HLA class II was observed in placental tissues of APS patients but not in healthy controls. Furthermore, autoantibodies against β2GPI/HLA class II complexes mediated complement-dependent cytotoxicity against cells expressing the complexes. These data suggest that β2GPI/HLA class II complexes are a target in APS that might be involved in the pathogenesis.

  16. Heterodinuclear Ni(ii) and Cu(ii) Schiff base complexes and their activity in oxygen reduction.

    PubMed

    Realista, Sara; Ramgi, Priscila; Cardoso, Bernardo de P; Melato, Ana I; Viana, Ana S; Calhorda, Maria José; Martinho, Paulo N

    2016-10-07

    New Cu(ii)/Ni(ii) heterodinuclear complexes with salphen-type ligands were synthesised via a stepwise template method. DFT studies were performed to understand their electronic properties, showing localisation of the HOMO on the Ni(ii) fragment, while in the oxidised species the spin density was high at some carbon phenolate atoms. These new complexes were potentiodynamically electropolymerised on glassy carbon and platinum. Atomic force microscopy was used to evaluate the influence of the metal centres on the morphology of the polymers, revealing how the presence of Cu(ii) increased the surface roughness. The oxygen reduction reaction was observed on both glassy carbon and platinum modified electrodes in neutral medium.

  17. Atlantic-Arctic exchange in a series of ocean model simulations (CORE-II)

    NASA Astrophysics Data System (ADS)

    Roth, Christina; Behrens, Erik; Biastoch, Arne

    2014-05-01

    In this study we aim to improve the understanding of exchange processes between the North Atlantic and the Arctic Ocean. The Nordic Sea builds an important connector between these regions, by receiving and modifying warm and saline Atlantic waters, and by providing dense overflow as a backbone of the Atlantic Meridional Overturning Circulation (AMOC). Using a hierarchy of global ocean/sea-ice models, the specific role of the Nordic Seas, both providing a feedback with the AMOC, but also as a modulator of the Atlantic water flowing into the Arctic Ocean, is examined. The models have been performed under the CORE-II protocol, in which atmospheric forcing of the past 60 years was applied in a subsequent series of 5 iterations. During the course of this 300-year long integration, the AMOC shows substantial changes, which are correlated with water mass characteristics in the Denmark Strait overflow characteristics. Quantitative analyses using Lagrangian trajectories explore the impact of these trends on the Arctic Ocean through the Barents Sea and the Fram Strait.

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

    PubMed

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

    2015-03-01

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

  19. Conserved oligomeric Golgi complex subunit 1 deficiency reveals a previously uncharacterized congenital disorder of glycosylation type II

    PubMed Central

    Foulquier, François; Vasile, Eliza; Schollen, Els; Callewaert, Nico; Raemaekers, Tim; Quelhas, Dulce; Jaeken, Jaak; Mills, Philippa; Winchester, Bryan; Krieger, Monty; Annaert, Wim; Matthijs, Gert

    2006-01-01

    The conserved oligomeric Golgi (COG) complex is a heterooctameric complex that regulates intraGolgi trafficking and the integrity of the Golgi compartment in eukaryotic cells. Here, we describe a patient with a mild form of congenital disorder of glycosylation type II (CDG-II) that is caused by a deficiency in the Cog1 subunit of the complex. This patient has a defect in both N- and O-glycosylation. Mass spectrometric analysis of the structures of the N-linked glycans released from glycoproteins from the patient's serum revealed a reduction in sialic acid and galactose residues. Peanut agglutinin (PNA) lectin staining revealed a decrease in sialic acids on core 1 mucin type O-glycans, indicating a combined defect in N- and O-glycosylation. Sequence analysis of the COG1 cDNA and gene identified a homozygous insertion of a single nucleotide (2659–2660insC), which is predicted to lead to a premature translation stop and truncation of the C terminus of the Cog1 protein by 80 amino acids. This mutation destabilizes several other COG subunits and alters their subcellular localization and hence the overall integrity of the COG complex. This results in reduced levels and/or altered Golgi localization of α-mannosidase II and β-1,4 galactosyltransferase I, which links it to the glycosylation deficiency. Transfection of primary fibroblasts of this patient with the full length hemagglutinin-tagged Cog1 indeed restored β-1,4 galactosyltransferase Golgi localization. We propose naming this disorder CDG-II/Cog1, or CDG-II caused by Cog1 deficiency. PMID:16537452

  20. Purification and spectroscopic characterization of photosystem II reaction center complexes isolated with or without Triton X-100.

    PubMed

    Eijckelhoff, C; van Roon, H; Groot, M L; van Grondelle, R; Dekker, J P

    1996-10-01

    The pigment composition of the isolated photosystem II reaction center complex in its most stable and pure form currently is a matter of considerable debate. In this contribution, we present a new method based on a combination of gel filtration chromatography and diode array detection to analyze the composition of photosystem II reaction center preparations. We show that the method is very sensitive for the detection of contaminants such as the core antenna protein CP47, pigment-free and denatured reaction center proteins, and unbound chlorophyll and pheophytin molecules. We also present a method by which the photosystem II reaction center complex is highly purified without using Triton X-100, and we show that in this preparation the contamination with CP47 is less than 0.1%. The results strongly indicate that the photosystem II reaction center complex in its most stable and pure form binds six chlorophyll a, two pheophytin a, and two beta-carotene molecules and that the main effect of Triton X-100 is the extraction of beta-carotene from the complex. Analysis of 4 K absorption and emission spectra indicates that the spectroscopic properties of this preparation are similar to those obtained by a short Triton X-100 treatment. In contrast, preparations obtained by long Triton X-100 treatment show decreased absorption of the shoulder at 684 nm in the 4 K absorption spectrum and an increased number of pigments that trap excitation energy at very low temperatures. We conclude that the 684 nm shoulder in the 4 K absorption spectrum should at least in part be attributed to the primary electron donor of photosystem II.

  1. Electron Transfer Studies of Ruthenium(II) Complexes with Biologically Important Phenolic Acids and Tyrosine.

    PubMed

    Rajeswari, Angusamy; Ramdass, Arumugam; Muthu Mareeswaran, Paulpandian; Rajagopal, Seenivasan

    2016-03-01

    The ruthenium(II) complexes having 2,2'-bipyridine and phenanthroline derivatives are synthesized and characterized. The photophysical properties of these complexes at pH 12.5 are studied. The electron transfer reaction of biologically important phenolic acids and tyrosine are studied using absorption, emission and transient absorption spectral techniques. Semiclassical theory is applied to calculate the rate of electron transfer between ruthenium(II) complexes and biologically important phenolic acids.

  2. Synthesis and spectroscopic characterization of high-spin mononuclear iron(II) p-semiquinonate complexes.

    PubMed

    Baum, Amanda E; Park, Heaweon; Lindeman, Sergey V; Fiedler, Adam T

    2014-12-01

    Two mononuclear iron(II) p-semiquinonate (pSQ) complexes have been generated via one-electron reduction of precursor complexes containing a substituted 1,4-naphthoquinone ligand. Detailed spectroscopic and computational analysis confirmed the presence of a coordinated pSQ radical ferromagnetically coupled to the high-spin Fe(II) center. The complexes are intended to model electronic interactions between (semi)quinone and iron cofactors in biology.

  3. Spectroscopic properties of the CP43 core antenna protein of photosystem II.

    PubMed

    Groot, M L; Frese, R N; de Weerd, F L; Bromek, K; Pettersson, A; Peterman, E J; van Stokkum, I H; van Grondelle, R; Dekker, J P

    1999-12-01

    CP43 is a chlorophyll-protein complex that funnels excitation energy from the main light-harvesting system of photosystem II to the photochemical reaction center. We purified CP43 from spinach photosystem II membranes in the presence of the nonionic detergent n-dodecyl-beta,D-maltoside and recorded its spectroscopic properties at various temperatures between 4 and 293 K by a number of polarized absorption and fluorescence techniques, fluorescence line narrowing, and Stark spectroscopy. The results indicate two "red" states in the Q(y) absorption region of the chlorophylls. The first peaks at 682.5 nm at 4 K, has an extremely narrow bandwidth with a full width at half-maximum of approximately 2.7 nm (58 cm(-1)) at 4 K, and has the oscillator strength of a single chlorophyll. The second peaks at approximately 679 nm, has a much broader bandshape, is caused by several excitonically interacting chlorophylls, and is responsible for all 4 K absorption at wavelengths longer than 685 nm. The Stark spectrum of CP43 resembles the first derivative of the absorption spectrum and has an exceptionally small overall size, which we attribute to opposing orientations of the monomer dipole moments of the excitonically coupled pigments.

  4. Density functional calculation of core-electron binding energies of transition metal carbonyl and nitrosyl complexes

    NASA Astrophysics Data System (ADS)

    Hu, Ching-Han; Chong, Delano P.

    1996-11-01

    Our recent procedure of the unrestricted generalized transition state (uGTS) model for density functional calculations of core-electron binding energies has been applied to seven carbonyl and nitrosyl inorganic complexes: Fe(CO) 5, Ni(CO) 4, Mn(CO) 4NO, Co(CO) 3NO, Fe(CO) 2(NO) 2, Mn(NO) 3CO and Cr(NO) 4. The exchange-correlation potential is based on a combined functional of Becke's exchange (B88) and Perdew's correlation (P86). The cc-pVTZ basis set was used for the calculation of neutral molecules, while for the partial cation created in the uGTS approach we scaled the cc-pVTZ basis set using a procedure based on Clementi and Raimondi's rules for atomic screening. The average absolute deviation of the calculated core-electron binding energy from experiment is 0.28 eV.

  5. Recovery of EDTA from complex solution using Cu(II) as precipitant and Cu(II) subsequent removal by electrolysis.

    PubMed

    Gyliene, O; Aikaite, J; Nivinskiene, O

    2004-12-10

    Ethylendiaminetetraacetate (EDTA) is a chelating agent widely used in industry and agriculture. Resistant to chemical and biological degradation EDTA represents a serious ecological problem. In order to avoid the outlet into the environment a new method of EDTA recycling has been proposed. The method involves substituting of the metal ions in EDTA complexes by Cu(II) and formation of an insoluble Cu2EDTA.4H2O compound at the excess of Cu(II) ions in weakly acidic solutions. Cu(II) ions substitute such metal ions as Ni(II), Zn(II), Co(II), Cd(II), Ca(II) and Mg(II). After treatment of the precipitate with water only, acidic or alkaline solutions the copper from the suspension formed can be removed by electrolysis. The highest current efficiency under galvanostatic conditions is in alkaline solutions, however, the highest yield of EDTA recovery is in acidic solutions. FT-IR investigations and chemical analysis of the precipitate formed have shown that in acidic and in alkaline solutions, H4EDTA and Na2H2EDTA.2H2O were formed, respectively. Electrolysis in acidic solutions gives the best results, i.e. the formed H4EDTA contains the highest amount of EDTA (95%) and the lowest amount of copper (0.01%).

  6. Artificial synthetic Mn(IV)Ca-oxido complexes mimic the oxygen-evolving complex in photosystem II.

    PubMed

    Chen, Changhui; Zhang, Chunxi; Dong, Hongxing; Zhao, Jingquan

    2015-03-14

    A novel family of heteronuclear Mn(IV)Ca-oxido complexes containing Mn(IV)Ca-oxido cuboidal moieties and reactive water molecules on Ca(2+) have been synthesized and characterized to mimic the oxygen-evolving complex (OEC) of photosystem II (PSII) in nature.

  7. Computational studies of the O2-evolving complex of photosystem II and biomimetic oxomanganese complexes

    PubMed Central

    Sproviero, Eduardo M.; Gascón, José A.; McEvoy, James P.; Brudvig, Gary W.; Batista, Victor S.

    2008-01-01

    In recent years, there has been considerable interest in studies of catalytic metal clusters in metalloproteins based on Density Functional Theory (DFT) quantum mechanics/molecular mechanics (QM/MM) hybrid methods. These methods explicitly include the perturbational influence of the surrounding protein environment on the structural/functional properties of the catalytic centers. In conjunction with recent breakthroughs in X-ray crystallography and advances in spectroscopic and biophysical studies, computational chemists are trying to understand the structural and mechanistic properties of the oxygen-evolving complex (OEC) embedded in photosystem II (PSII). Recent studies include the development of DFT-QM/MM computational models of the Mn4Ca cluster, responsible for photosynthetic water oxidation, and comparative quantum mechanical studies of biomimetic oxomanganese complexes. A number of computational models, varying in oxidation and protonation states and ligation of the catalytic center by amino acid residues, water, hydroxide and chloride have been characterized along the PSII catalytic cycle of water splitting. The resulting QM/MM models are consistent with available mechanistic data, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction data and extended X-ray absorption fine structure (EXAFS) measurements. Here, we review these computational efforts focused towards understanding the catalytic mechanism of water oxidation at the detailed molecular level. PMID:19190716

  8. DNA cleavage by homo- and heterotetranuclear Cu(II) and Mn(II) complexes with tetrathioether-tetrathiol moiety.

    PubMed

    Dülger, S; Saglam, N; Beldüz, A O; Güner, S; Karaböcek, S

    2000-09-01

    Novel homotetranuclear Cu(II) and heteronuclear Cu(II)-Mn(II) complexes with tetrathioether-tetrathiol moiety have been prepared and their DNA relaxation activities with plasmid pCYTEXP (5kb) were electrophoretically established. The cleavage products analyzed by neutral agarose gel electrophoresis indicated that the interaction of the metal complexes with supercoiled plasmid DNA yielded linear, nicked or degraded DNA. The relaxation activities of both homo- and heterotetranuclear (SK4) complexes are time- and concentration-dependent. The findings suggest that SK4 with potent nucleolytic activity is a good nuclease substitute in the presence ofcooxidant. Furthermore, the observation of induction of DNA into smaller fragments by SK4 is also significant.

  9. Synthesis, characterization and biological activities of Cu(II), Co(II), Mn(II), Fe(II), and UO2(VI) complexes with a new Schiff Base hydrazone: O-hydroxyacetophenone-7-chloro-4-quinoline hydrazone.

    PubMed

    Al-Shaalan, Nora H

    2011-10-13

    The Schiff base hydrazone ligand HL was prepared by the condensation reaction of 7-chloro-4-quinoline with o-hydroxyacetophenone. The ligand behaves either as monobasic bidentate or dibasic tridentate and contain ONN coordination sites. This was accounted for be the presence in the ligand of a phenolic azomethine and imine groups. It reacts with Cu(II), Ni(II), Co(II), Mn(II), UO(2) (VI) and Fe(II) to form either mono- or binuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, NMR, Mass, and UV-Visible spectra. The magnetic moments and electrical conductance of the complexes were also determined. The Co(II), Ni(II) and UO(2) (VI) complexes are mononuclear and coordinated to NO sites of two ligand molecules. The Cu(II) complex has a square-planar geometry distorted towards tetrahedral, the Ni(II) complex is octahedral while the UO(2) (VI) complex has its favoured heptacoordination. The Co(II), Mn(II) complexes and also other Ni(II) and Fe(III) complexes, which were obtained in the presence of Li(OH) as deprotonating agent, are binuclear and coordinated via the NNNO sites of two ligand molecules. All the binuclear complexes have octahedral geometries and their magnetic moments are quite low compared to the calculated value for two metal ions complexes and thus antiferromagnetic interactions between the two adjacent metal ions. The ligand HL and metal complexes were tested against a strain of Gram +ve bacteria (Staphylococcus aureus), Gram -ve bacteria (Escherichia coli), and fungi (Candida albicans). The tested compounds exhibited high antibacterial activities.

  10. Docking and molecular dynamics simulations of the ternary complex nisin2:lipid II

    PubMed Central

    Mulholland, Sam; Turpin, Eleanor R.; Bonev, Boyan B.; Hirst, Jonathan D.

    2016-01-01

    Lanthionine antibiotics are an important class of naturally-occurring antimicrobial peptides. The best-known, nisin, is a commercial food preservative. However, structural and mechanistic details on nisin-lipid II membrane complexes are currently lacking. Recently, we have developed empirical force-field parameters to model lantibiotics. Docking and molecular dynamics (MD) simulations have been used to study the nisin2:lipid II complex in bacterial membranes, which has been put forward as the building block of nisin/lipid II binary membrane pores. An Ile1Trp mutation of the N-terminus of nisin has been modelled and docked onto lipid II models; the computed binding affinity increased compared to wild-type. Wild-type nisin was also docked onto three different lipid II structures and a stable 2:1 nisin:lipid II complex formed. This complex was inserted into a membrane. Six independent MD simulations revealed key interactions in the complex, specifically the N-terminal engagement of nisin with lipid II at the pyrophosphate and C-terminus of the pentapeptide chain. Nisin2 inserts into the membrane and we propose this as the first step in pore formation, mediated by the nisin N-terminus–lipid II pentapeptide hydrogen bond. The lipid II undecaprenyl chain adopted different conformations in the presence of nisin, which may also have implications for pore formation. PMID:26888784

  11. Calculation of scattering characteristic of complex target on multi-core platform

    NASA Astrophysics Data System (ADS)

    Guo, Xing; Wu, Zhensen; Linghu, Longxiang

    2013-09-01

    The scattering characteristic of complex target from terrestrial and celestial background radiation has been widely used in such engineering fields as remote sensing, feature extraction, tracking and recognition of target thus having been an attractive field for many scientists for decades. In our method, the model of target is constructed using 3DMAX and the surface is divided into triangle facets firstly. Bidirectional Reflectance Distribution Function (BRDF) is introduced and MODTRAN is applied to calculate background radiation for a given time at a given place. Finally the scattering of each facet is added up to get the scattering of the target. As the background radiance comes in all directions and in a wide spectrum and the complex target always consists of thousands of facets, in general it takes hours to complete the calculation. Consequently this limits its use in the real time applications. Recent years have seen the continual development of multi-core CPU. As a result parallel programming on multi-cores has been more and more popular. In this paper, the openMP, Intel CILK ++, Intel Threading Building Blocks (TBB) are used separately to leverage the processing power of multi-cores processors. Our experiments are conducted on a DELL desktop based on an Intel I7- 2600K CPU running at 3.40 GHz with 8 cores and 16.0 GB RAM. The Intel Composer 2013 is employed to build the program. Also in OpenMP implementation, gcc is used. The results demonstrate that highest speedups for three parallel models are 5.06X, 5.02X, 5.15X respectively.

  12. Joint toxicity of tetracycline with copper(II) and cadmium(II) to Vibrio fischeri: effect of complexation reaction.

    PubMed

    Tong, Fei; Zhao, Yanping; Gu, Xueyuan; Gu, Cheng; Lee, Charles C C

    2015-03-01

    Co-contamination of antibiotic and heavy metals commonly occurs in the environment. Tetracycline (TC), a common antibiotic, can behave as an efficient organic ligand to complex with cations. In this paper, the joint toxicity of TC with two commonly existing metals, copper(II) and cadmium(II), towards a luminescent bacteria, Vibrio fischeri, are investigated. Results showed that coexistence of TC and Cu(II) showed a significant antagonistic effect, while TC and Cd(II) showed a synergistic effect. The aqueous speciation of TC with two metal cations was calculated using a chemical equilibrium software Visual MINTEQ and results indicated that a strong complexation exist between TC and Cu(II), while much weaker interaction between TC and Cd(II). Traditional joint toxicity prediction model based on independent action failed to predict the combined toxicity of TC with metals. A new method based on speciation calculation was used to evaluate the joint toxicity of ligands and cations. It is assumed that the metal-ligand complexes are non-toxic to V. fischeri and the joint toxicity is determined by the sum of toxic unit of free metal-ions and free organic ligands. It explained the joint toxicity of the mixed systems reasonably well. Meanwhile, citric acid (CA) and fulvic acid (FA) were also introduced in this study to provide a benchmark comparison with TC. Results showed it is also valid for mixed systems of CA and FA with metals except for the Cd-CA mixture.

  13. A core-shell structured nanocomposite material for detection, adsorption and removal of Hg(II) ions in water.

    PubMed

    Li, Le; Tang, Shuangyang; Ding, Dexin; Hu, Nan; Yang, Shengyuan; He, Shuya; Wang, Yongdong; Tan, Yan; Sun, Jing

    2012-11-01

    In this paper, a core-shell structured nanocomposite material was prepared for the detection, adsorption and removal of Hg(ll) ions in aqueous solution. The core was made from Fe3O4 nanoparticles with superparamagnetic behavior and the outer shell was made from amorphous silica modified with pyrene-based sensing-probes. The material could detect and adsorb Hg(II) ions in aqueous solution due to its surface being modified with pyrene-based sensing-probes, and could easily be removed from the solution by magnetic force because of its core being made from magnetic Fe3O4 nanoparticles. This multifunctional core-shell structure was confirmed and characterized by TEM, IR spectra, TGA, XRD and N2 adsorption/desorption isotherms. Experiments were conducted on its functions of detection, adsorption and removal of Hg(II) ions in aqueous solution. The experimental results showed that this composite material had high sensitivity and unique selectivity to Hg(II), and that it could easily be removed from the solution.

  14. An unlikely DNA cleaving agent: A photo-active trinuclear Cu(II) complex based on hexaazatriphenylene.

    PubMed

    Williams, Dominique E; Fischer, Christina M; Kassai, Miki; Gude, Lourdes; Fernández, María-José; Lorente, Antonio; Grant, Kathryn B

    2017-03-01

    This paper describes the synthesis of a trinuclear Cu(II) complex (4) containing a central 1,4,5,8,9,12-hexaazatriphenylene-hexacarboxylate (hat) core (3). Low, micromolar concentrations of the negatively charged parent ligand 3 and the neutral trinuclear complex 4 were found to photocleave negatively charged pUC19 plasmid DNA with high efficiency at neutral pH (350nm, 50min, 22°C). The interactions of complex 4 with double-helical DNA were studied in detail. Scavenger and colorimetric assays pointed to the formation of Cu(I), superoxide anion radicals, hydrogen peroxide, and hydroxyl radicals during photocleavage reactions. UV-visible absorption, circular dichroism, DNA thermal denaturation, and fluorescence data suggested that the Cu(II) complex contacts double-stranded DNA in an external fashion. The persistent association of ligand 3 and complex 4 with Na(I) and/or other cations in aqueous solution might facilitate electrostatic DNA interactions.

  15. Alkali Metal Variation and Twisting of the FeNNFe Core in Bridging Diiron Dinitrogen Complexes.

    PubMed

    McWilliams, Sean F; Rodgers, Kenton R; Lukat-Rodgers, Gudrun; Mercado, Brandon Q; Grubel, Katarzyna; Holland, Patrick L

    2016-03-21

    Alkali metal cations can interact with Fe-N2 complexes, potentially enhancing back-bonding or influencing the geometry of the iron atom. These influences are relevant to large-scale N2 reduction by iron, such as in the FeMoco of nitrogenase and the alkali-promoted Haber-Bosch process. However, to our knowledge there have been no systematic studies of a large range of alkali metals regarding their influence on transition metal-dinitrogen complexes. In this work, we varied the alkali metal in [alkali cation]2[LFeNNFeL] complexes (L = bulky β-diketiminate ligand) through the size range from Na(+) to K(+), Rb(+), and Cs(+). The FeNNFe cores have similar Fe-N and N-N distances and N-N stretching frequencies despite the drastic change in alkali metal cation size. The two diketiminates twist relative to one another, with larger dihedral angles accommodating the larger cations. In order to explain why the twisting has so little influence on the core, we performed density functional theory calculations on a simplified LFeNNFeL model, which show that the two metals surprisingly do not compete for back-bonding to the same π* orbital of N2, even when the ligand planes are parallel. This diiron system can tolerate distortion of the ligand planes through compensating orbital energy changes, and thus, a range of ligand orientations can give very similar energies.

  16. Alkali Metal Variation and Twisting of the FeNNFe Core in Bridging Diiron Dinitrogen Complexes

    PubMed Central

    2016-01-01

    Alkali metal cations can interact with Fe–N2 complexes, potentially enhancing back-bonding or influencing the geometry of the iron atom. These influences are relevant to large-scale N2 reduction by iron, such as in the FeMoco of nitrogenase and the alkali-promoted Haber–Bosch process. However, to our knowledge there have been no systematic studies of a large range of alkali metals regarding their influence on transition metal–dinitrogen complexes. In this work, we varied the alkali metal in [alkali cation]2[LFeNNFeL] complexes (L = bulky β-diketiminate ligand) through the size range from Na+ to K+, Rb+, and Cs+. The FeNNFe cores have similar Fe–N and N–N distances and N–N stretching frequencies despite the drastic change in alkali metal cation size. The two diketiminates twist relative to one another, with larger dihedral angles accommodating the larger cations. In order to explain why the twisting has so little influence on the core, we performed density functional theory calculations on a simplified LFeNNFeL model, which show that the two metals surprisingly do not compete for back-bonding to the same π* orbital of N2, even when the ligand planes are parallel. This diiron system can tolerate distortion of the ligand planes through compensating orbital energy changes, and thus, a range of ligand orientations can give very similar energies. PMID:26925968

  17. Synthesis, spectroscopic characterization, DNA interaction and biological activities of Mn(II), Co(II), Ni(II) and Cu(II) complexes with [(1H-1,2,4-triazole-3-ylimino)methyl]naphthalene-2-ol

    NASA Astrophysics Data System (ADS)

    Gaber, Mohamed; El-Wakiel, Nadia A.; El-Ghamry, Hoda; Fathalla, Shaimaa K.

    2014-11-01

    Manganese(II), cobalt(II), nickel(II) and copper(II) complexes of [(1H-1,2,4-triazole-3-ylimino)methyl]naphthalene-2-ol have been synthesized. The structure of complexes have been characterized by elemental analysis, molar conductance, magnetic moment measurements and spectral (IR, 1H NMR, EI-mass, UV-Vis and ESR), and thermal studies. The results showed that the chloro and nitrato Cu(II) complexes have octahedral geometry while Ni(II), Co(II) and Mn(II) complexes in addition to acetato Cu(II) complex have tetrahedral geometry. The possible structures of the metal complexes have been computed using the molecular mechanic calculations using the hyper chem. 8.03 molecular modeling program to confirm the proposed structures. The kinetic and thermodynamic parameters of the thermal decomposition steps were calculated from the TG curves. The binding modes of the complexes with DNA have been investigated by UV-Vis absorption titration. The results showed that the mode of binding of the complexes to DNA is intercalative or non-intercalative binding modes. Schiff base and its metal complexes have been screened for their in vitro antimicrobial activities against Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli and Pesudomonas aeruginosa), fungi (Asperigllus flavus and Mucer) and yeast (Candida albicans and Malassezia furfur).

  18. Synthesis, characterization and biological activity of Cu(II), Ni(II) and Zn(II) complexes of biopolymeric Schiff bases of salicylaldehydes and chitosan.

    PubMed

    de Araújo, Eliene Leandro; Barbosa, Hellen Franciane Gonçalves; Dockal, Edward Ralph; Cavalheiro, Éder Tadeu Gomes

    2017-02-01

    Schiff bases have been prepared from biopolymer chitosan and salicylaldehyde, 5-methoxysalicylaldehyde, and 5-nitrosalicylaldehyde. Ligands were synthesized in a 1:1.5mol ratio, and their Cu(II), Ni(II) and Zn(II) complexes in a 1:1mol ratio (ligand:metal). Ligands were characterized by (1)H NMR and FTIR, resulting in degrees of substitution from 43.7 to 78.7%. Complexes were characterized using FTIR, electronic spectra, XPRD. The compounds were confirmed by the presence of an imine bond stretching in the 1630-1640cm(-1) and νMetal-N and νMetal-O at <600cm(-1). Electronic spectra revealed that both Cu(II) and Ni(II) complexes present a square plane geometry. The crystallinity values were investigated by X-ray powder diffraction. Thermal behavior of all compounds was evaluated by TGA/DTG and DTA curves with mass losses related to dehydration and decomposition, with characteristic events for ligand and complexes. Schiff base complexes presented lower thermal stability and crystallinity than the starting chitosan. Residues were the metallic oxides as confirmed by XPRD, whose amounts were used in the calculation of the percentage of complexed metal ions. Surface morphologies were analyzed with SEM-EDAX. Preliminary cytotoxicity tests were performed using MTT assay with HeLa cells. Despite the differences in solubility, the free bases presented relatively low toxicity.

  19. Dinuclear metal(ii)-acetato complexes based on bicompartmental 4-chlorophenolate: syntheses, structures, magnetic properties, DNA interactions and phosphodiester hydrolysis.

    PubMed

    Massoud, Salah S; Ledet, Catherine C; Junk, Thomas; Bosch, Simone; Comba, Peter; Herchel, Radovan; Hošek, Jan; Trávníček, Zdeněk; Fischer, Roland C; Mautner, Franz A

    2016-08-09

    A series of dinuclear metal(ii)-acetato complexes: [Ni2(μ-L(Cl)O)(μ2-OAc)2](PF6)·3H2O (1), [Ni2(μ-L(Cl)O)(μ2-OAc)2](ClO4)·CH3COCH3 (2), [Cu2(μ-L(Cl)O)(μ2-OAc)(ClO4)](ClO4) (3), [Cu2(μ-L(Cl)O)(OAc)2](PF6)·H2O (4), [Zn2(μ-L(Cl)O)(μ2-OAc)2](PF6) (5) and [Mn2(L(Cl)-O)(μ2-OAc)2](ClO4)·H2O (6), where L(Cl)O(-) = 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-chlorophenolate, were synthesized. The complexes were structurally characterized by spectroscopic techniques and single crystal X-ray crystallography. Six-coordinate geometries with doubly bridged acetato ligands were found in Ni(ii), Zn(ii) and Mn(ii) complexes 1, 2, 5 and 6, whereas with Cu(ii) complexes a five-coordinate species was obtained with 4, and mixed five- and six-coordinate geometries with a doubly bridged dimetal core were observed in 3. The magnetic properties of complexes 1-4 and 6 were studied at variable temperatures and revealed weak to very weak antiferromagnetic interactions in 1, 2, 4 and 6 (J = -0.55 to -9.4 cm(-1)) and ferromagnetic coupling in 3 (J = 15.4 cm(-1)). These results are consistent with DFT calculations performed at the B3LYP/def2-TZVP(-f) level of theory. Under physiological conditions, the interaction of the dinculear complexes 1-5 with supercoiled plasmid ds-DNA did not show any pronounced nuclease activity, but Ni(ii) complexes 1 and 2 revealed a strong ability to unwind the supercoiled conformation of ds-DNA. The mechanistic studies performed on the interaction of the Ni(ii) complexes with DNA demonstrated the important impact of the nickel(ii) ion in the unwinding process. In combination with the DNA study, the phosphatase activity of complexes 1, 3, and 5 was examined by the phosphodiester hydrolysis of bis(2,4-dinitrophenol)phosphate (BDNPP) in the pH range of 5.5-10.5 at 25 °C. The Michaelis-Menten kinetics performed at pH 7 and 10.7 showed that catalytic efficiencies kcat/KM (kcat = catalytic rate constant, KM = substrate binding constant) decrease in the order

  20. Rheological transitions in the middle crust: insights from Cordilleran metamorphic core complexes

    NASA Astrophysics Data System (ADS)

    Cooper, Frances J.; Platt, John P.; Behr, Whitney M.

    2017-02-01

    High-strain mylonitic rocks in Cordilleran metamorphic core complexes reflect ductile deformation in the middle crust, but in many examples it is unclear how these mylonites relate to the brittle detachments that overlie them. Field observations, microstructural analyses, and thermobarometric data from the footwalls of three metamorphic core complexes in the Basin and Range Province, USA (the Whipple Mountains, California; the northern Snake Range, Nevada; and Ruby Mountains-East Humboldt Range, Nevada), suggest the presence of two distinct rheological transitions in the middle crust: (1) the brittle-ductile transition (BDT), which depends on thermal gradient and tectonic regime, and marks the switch from discrete brittle faulting and cataclasis to continuous, but still localized, ductile shear, and (2) the localized-distributed transition, or LDT, a deeper, dominantly temperature-dependent transition, which marks the switch from localized ductile shear to distributed ductile flow. In this model, brittle normal faults in the upper crust persist as ductile shear zones below the BDT in the middle crust, and sole into the subhorizontal LDT at greater depths.In metamorphic core complexes, the presence of these two distinct rheological transitions results in the development of two zones of ductile deformation: a relatively narrow zone of high-stress mylonite that is spatially and genetically related to the brittle detachment, underlain by a broader zone of high-strain, relatively low-stress rock that formed in the middle crust below the LDT, and in some cases before the detachment was initiated. The two zones show distinct microstructural assemblages, reflecting different conditions of temperature and stress during deformation, and contain superposed sequences of microstructures reflecting progressive exhumation, cooling, and strain localization. The LDT is not always exhumed, or it may be obscured by later deformation, but in the Whipple Mountains, it can be directly

  1. Reversing the relative 3MLCT-3MC order in Fe(ii) complexes using cyclometallating ligands: a computational study aiming at luminescent Fe(ii) complexes.

    PubMed

    Dixon, Isabelle M; Alary, Fabienne; Boggio-Pasqua, Martial; Heully, Jean-Louis

    2015-08-14

    Following a computational approach, the use of strongly electron-donating cyclometallating ligands has allowed us to increase the (3)MC-(3)MLCT gap dramatically in Fe(ii) bis(tridentate) polypyridine complexes, and eventually to reverse the ordering between these states, yielding a (3)MLCT state that is clearly more stable than the (3)MC state. Simultaneously, the quintet excited states ((5)MC and (5)MLCT) are displaced away from the region (in terms of geometry and energy) where classical photophysics occur, allowing us to avoid magnetism. The situation is thus similar to that of classical ruthenium polypyridine complexes. This opens the way towards luminescent iron(ii) complexes, in particular Fe(ii)bis(6-phenyl-2,2'-bipyridine) Fe(NNC)(2).

  2. The EARP Complex and Its Interactor EIPR-1 Are Required for Cargo Sorting to Dense-Core Vesicles

    PubMed Central

    Topalidou, Irini; Cattin-Ortolá, Jérôme; MacCoss, Michael J.

    2016-01-01

    The dense-core vesicle is a secretory organelle that mediates the regulated release of peptide hormones, growth factors, and biogenic amines. Dense-core vesicles originate from the trans-Golgi of neurons and neuroendocrine cells, but it is unclear how this specialized organelle is formed and acquires its specific cargos. To identify proteins that act in dense-core vesicle biogenesis, we performed a forward genetic screen in Caenorhabditis elegans for mutants defective in dense-core vesicle function. We previously reported the identification of two conserved proteins that interact with the small GTPase RAB-2 to control normal dense-core vesicle cargo-sorting. Here we identify several additional conserved factors important for dense-core vesicle cargo sorting: the WD40 domain protein EIPR-1 and the endosome-associated recycling protein (EARP) complex. By assaying behavior and the trafficking of dense-core vesicle cargos, we show that mutants that lack EIPR-1 or EARP have defects in dense-core vesicle cargo-sorting similar to those of mutants in the RAB-2 pathway. Genetic epistasis data indicate that RAB-2, EIPR-1 and EARP function in a common pathway. In addition, using a proteomic approach in rat insulinoma cells, we show that EIPR-1 physically interacts with the EARP complex. Our data suggest that EIPR-1 is a new interactor of the EARP complex and that dense-core vesicle cargo sorting depends on the EARP-dependent trafficking of cargo through an endosomal sorting compartment. PMID:27191843

  3. Synthesis, spectroscopic characterization, molecular modeling and potentiometric studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with 1,1-diaminobutane-Schiff base

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.

    2014-08-01

    Complexes of cobalt(II), nickel(II), copper(II) and zinc(II) of general composition [M(L)(H2O)2]·2H2O have been synthesized [L = N,N";-bis(2-hydroxybenzylidene)-1,1-diaminobutane]. The elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, IR, UV, NMR, SEM, EDX, thermal and EPR spectral studies of the compounds led to the conclusion that the ligand acts as a tetradentate manner. The molar conductance of the complexes in fresh solution of DMSO lies in the range of 7.46-9.13 Ω-1 cm2 mol-1 indicating their non-electrolytic behavior. On the basis of analytical and spectroscopic techniques, octahedral geometry of the complexes was proposed. The Schiff base acts as tetradentate ligand, coordinated through deprotonated phenolic oxygen and azomethine nitrogen atoms. The ligand field parameters were calculated for Co(II), Ni(II) and Cu(II) complexes and their values were found in the range reported for a octahedral structure. The molecular parameters of the ligand and its Co(II), Ni(II), Cu(II) and Zn(II) complexes have been calculated. Protonation constants of Schiff base and stability constants of their binary metal complexes have been determined potentiometrically in 50% DMSO-water media at 25 °C and ionic strength 0.10 M sodium perchlorate.

  4. Synthesis, characterization and biological activity of some new VO(IV), Co(II), Ni(II), Cu(II) and Zn(II) complexes of chromone based NNO Schiff base derived from 2-aminothiazole

    NASA Astrophysics Data System (ADS)

    Kalanithi, M.; Kodimunthiri, D.; Rajarajan, M.; Tharmaraj, P.

    2011-11-01

    Coordination compounds of VO(IV), Co(II), Ni(II), Cu(II) and Zn(II) with the Schiff base obtained through the condensation of 2-aminothiazole with 3-formyl chromone were synthesized. The compounds were characterized by 1H, 13C NMR, UV-Vis, IR, Mass, EPR, molar conductance and magnetic susceptibility measurements. The Cu(II) complex possesses tetrahedrally distorted square planar geometry whereas Co(II), Ni(II), and Zn(II) show distorted tetrahedral geometry. The VO(IV) complex shows square pyramidal geometry. The cyclic voltammogram of Cu (II) complex showed a well defined redox couple Cu(II)/Cu(I) with quasireversible nature. The antimicrobial activity against the species Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albigans and Aspergillus niger was screened and compared to the activity of the ligand. Emission spectrum was recorded for the ligand and the metal(II) complexes. The second harmonic generation (SHG) efficiency was measured and found to have one fourth of the activity of urea. The SEM image of the copper(II) complex implies that the size of the particles is 2 μm.

  5. Stability Constants of Mixed Ligand Complexes of Nickel(II) with Adenine and Some Amino Acids

    PubMed Central

    Türkel, Naciye

    2015-01-01

    Nickel is one of the essential trace elements found in biological systems. It is mostly found in nickel-based enzymes as an essential cofactor. It forms coordination complexes with amino acids within enzymes. Nickel is also present in nucleic acids, though its function in DNA or RNA is still not clearly understood. In this study, complex formation tendencies of Ni(II) with adenine and certain L-amino acids such as aspartic acid, glutamic acid, asparagine, leucine, phenylalanine, and tryptophan were investigated in an aqueous medium. Potentiometric equilibrium measurements showed that both binary and ternary complexes of Ni(II) form with adenine and the above-mentioned L-amino acids. Ternary complexes of Ni(II)-adenine-L-amino acids are formed by stepwise mechanisms. Relative stabilities of the ternary complexes are compared with those of the corresponding binary complexes in terms of Δlog10⁡K, log10⁡X, and % RS values. It was shown that the most stable ternary complex is Ni(II):Ade:L-Asn while the weakest one is Ni(II):Ade:L-Phe in aqueous solution used in this research. In addition, results of this research clearly show that various binary and ternary type Ni(II) complexes are formed in different concentrations as a function of pH in aqueous solution. PMID:26843852

  6. Molecular structure and spectroscopic studies on novel complexes of coumarin-3-carboxylic acid with Ni(II), Co(II), Zn(II) and Mn(II) ions based on density functional theory

    NASA Astrophysics Data System (ADS)

    Creaven, B. S.; Devereux, M.; Georgieva, I.; Karcz, D.; McCann, M.; Trendafilova, N.; Walsh, M.

    2011-12-01

    Novel Ni(II), Co(II), Zn(II) and Mn(II) complexes of coumarin-3-carboxylic acid (HCCA) were studied at experimental and theoretical levels. The complexes were characterised by elemental analyses, FT-IR, 1H NMR, 13C NMR and UV-Vis spectroscopy and by magnetic susceptibility measurements. The binding modes of the ligand and the spin states of the metal complexes were established by means of molecular modelling of the complexes studied and calculation of their IR, NMR and absorption spectra at DFT(TDDFT)/B3LYP level. The experimental and calculated data verified high spin Ni(II), Co(II) and Mn(II) complexes and a bidentate binding through the carboxylic oxygen atoms (CCA2). The model calculations predicted pseudo octahedral trans-[M(CCA2) 2(H 2O) 2] structures for the Zn(II), Ni(II) and Co(II) complexes and a binuclear [Mn 2(CCA2) 4(H 2O) 2] structure. Experimental and calculated 1H, 13C NMR, IR and UV-Vis data were used to distinguish the two possible bidentate binding modes (CCA1 and CCA2) as well as mononuclear and binuclear structures of the metal complexes.

  7. Molecular structure and spectroscopic studies on novel complexes of coumarin-3-carboxylic acid with Ni(II), Co(II), Zn(II) and Mn(II) ions based on density functional theory.

    PubMed

    Creaven, B S; Devereux, M; Georgieva, I; Karcz, D; McCann, M; Trendafilova, N; Walsh, M

    2011-12-15

    Novel Ni(II), Co(II), Zn(II) and Mn(II) complexes of coumarin-3-carboxylic acid (HCCA) were studied at experimental and theoretical levels. The complexes were characterised by elemental analyses, FT-IR, (1)H NMR, (13)C NMR and UV-Vis spectroscopy and by magnetic susceptibility measurements. The binding modes of the ligand and the spin states of the metal complexes were established by means of molecular modelling of the complexes studied and calculation of their IR, NMR and absorption spectra at DFT(TDDFT)/B3LYP level. The experimental and calculated data verified high spin Ni(II), Co(II) and Mn(II) complexes and a bidentate binding through the carboxylic oxygen atoms (CCA2). The model calculations predicted pseudo octahedral trans-[M(CCA2)(2)(H(2)O)(2)] structures for the Zn(II), Ni(II) and Co(II) complexes and a binuclear [Mn(2)(CCA2)(4)(H(2)O)(2)] structure. Experimental and calculated (1)H, (13)C NMR, IR and UV-Vis data were used to distinguish the two possible bidentate binding modes (CCA1 and CCA2) as well as mononuclear and binuclear structures of the metal complexes.

  8. Complexation Effect on Redox Potential of Iron(III)-Iron(II) Couple: A Simple Potentiometric Experiment

    ERIC Educational Resources Information Center

    Rizvi, Masood Ahmad; Syed, Raashid Maqsood; Khan, Badruddin

    2011-01-01

    A titration curve with multiple inflection points results when a mixture of two or more reducing agents with sufficiently different reduction potentials are titrated. In this experiment iron(II) complexes are combined into a mixture of reducing agents and are oxidized to the corresponding iron(III) complexes. As all of the complexes involve the…

  9. Complex molecules in galactic dust cores: Biologically interesting molecules and dust chemistry

    NASA Astrophysics Data System (ADS)

    Liu, Shen-Yuan

    2000-06-01

    The astronomical study of molecules has been an essential research field since the development of radio astronomy. Presently nearly 120 molecules have been identified in interstellar and circumstellar environments. The complexity of molecular species, and particularly organic molecules, that can be synthesized in the interstellar medium (ISM) leads to one interesting and important subfield in interstellar molecular studies, namely, the search and study for molecules of possible biological interest. Observationally, complex and most saturated molecules are observed exclusively toward compact hot, dense regions, often called ``hot cores'', in molecular clouds. To account for the observed amount of saturated organic molecules, interstellar dust particles play an important role. It has often been suggested that solid state reactions on grain surfaces provide an efficient way to synthesis saturated organic molecules. The objective of this study is to obtain observational data on biologically interesting molecules and to study important complex interstellar molecules. Since hot molecular cores are inherently compact, interferometric observations are therefore an ideal approach to study these sources. All our observations were all made with the Berkeley-Illinois-Maryland-Association (BIMA) Array. We conducted the first survey of formic acid (HCOOH) with an interferometric array, and identified at least three sources. HCOOH is found with column densities above 1015 cm-2 in these sources. The correlation between HCOOH and HCOOCH3 emission implies a surface chemistry origin of HCOOH. Details of the results are given in Chapter 2. Meanwhile, we continued to search for molecules of biological interest, namely urea, acetic acid, and glycine. In Chapter 3, the results of column density limits set by our observations are discussed. We have also investigated properties of individual hot molecular cores. It is very important to obtain the physical and chemical properties of these

  10. Control of size in losartan/copper(II) coordination complex hydrophobic precipitate.

    PubMed

    Denadai, Ângelo M L; Da Silva, Jeferson G; Guimarães, Pedro P G; Gomes, Leonardo Bertolini S; Mangrich, Antonio S; de Rezende, Edivaltrys I P; Daniel, Izabela M P; Beraldo, Heloísa; Sinisterra, Rubén D

    2013-10-01

    Reaction of highly soluble orally active, non-peptide antihypertensive drug losartan with copper(II) leads to the spontaneous formation of a very insoluble 2:1 covalent complex, which self assembles in a hydrophobic supramolecular structure of nanometric dimensions. Thermal analysis showed that Los/Cu(II) complex presents intermediate stability in comparison with its precursors KLos and Cu(OAc)2·H2O. Isothermal titration calorimetry indicated complexation to be a stepwise process, driven by enthalpy and entropy. Zeta potential and DLS measurements showed that it is possible to control the size and charge of nanoprecipitates by adjusting the relative concentration of Los(-) and Cu(II).

  11. Syntheses, characterizations and structures of NO donor Schiff base ligands and nickel(II) and copper(II) complexes

    NASA Astrophysics Data System (ADS)

    Şenol, Cemal; Hayvali, Zeliha; Dal, Hakan; Hökelek, Tuncer

    2011-06-01

    New Schiff base derivatives ( L 1 and L 2) were prepared by the condensation of 2-hydroxy-3-methoxybenzaldehyde ( o-vanillin) and 3-hydroxy-4-methoxybenzaldehyde ( iso-vanillin) with 5-methylfurfurylamine. Two new complexes [Ni(L 1) 2] and [Cu(L 1) 2] have been synthesized with bidentate NO donor Schiff base ligand ( L 1). The Ni(II) and Cu(II) atoms in each complex are four coordinated in a square planar geometry. Schiff bases ( L 1 and L 2) and complexes [Ni(L 1) 2] and [Cu(L 1) 2] were characterized by elemental analyses, FT-IR, UV-vis, mass and 1H, 13C NMR spectroscopies. The crystal structures of the ligand ( L 2) and complexes [Ni(L 1) 2] and [Cu(L 1) 2] have also been determined by using X-ray crystallographic technique.

  12. Decommissioning of Experimental Breeder Reactor - II Complex, Post Sodium Draining

    SciTech Connect

    J. A. Michelbacher; S. Paul Henslee; Collin J. Knight; Steven R. sherman

    2005-09-01

    The Experimental Breeder Reactor - II (EBR-II) was shutdown in September 1994 as mandated by the United States Department of Energy. This sodium-cooled reactor had been in service since 1964. The bulk sodium was drained from the primary and secondary systems and processed. Residual sodium remaining in the systems after draining was converted into sodium bicarbonate using humid carbon dioxide. This technique was tested at Argonne National Laboratory in Illinois under controlled conditions, then demonstrated on a larger scale by treating residual sodium within the EBR-II secondary cooling system, followed by the primary tank. This process, terminated in 2002, was used to place a layer of sodium bicarbonate over all exposed surfaces of sodium. Treatment of the remaining EBR-II sodium is governed by the Resource Conservation and Recovery Act (RCRA). The Idaho Department of Environmental Quality issued a RCRA Operating Permit in 2002, mandating that all hazardous materials be removed from EBR-II within a 10 year period, with the ability to extend the permit and treatment period for another 10 years. A preliminary plan has been formulated to remove the remaining sodium and NaK from the primary and secondary systems using moist carbon dioxide, steam and nitrogen, and a water flush. The moist carbon dioxide treatment was resumed in May 2004. As of August 2005, approximately 60% of the residual sodium within the EBR-II primary tank had been treated. This process will continue through the end of 2005, when it is forecast that the process will become increasingly ineffective. At that time, subsequent treatment processes will be planned and initiated. It should be noted that the processes and anticipated costs associated with these processes are preliminary. Detailed engineering has not been performed, and approval for these methods has not been obtained from the regulator or the sponsors.

  13. DNA cleavage, antibacterial, antifungal and anthelmintic studies of Co(II), Ni(II) and Cu(II) complexes of coumarin Schiff bases: Synthesis and spectral approach

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Prabhakara, Chetan T.; Halasangi, Bhimashankar M.; Toragalmath, Shivakumar S.; Badami, Prema S.

    2015-02-01

    The metal complexes of Co(II), Ni(II) and Cu(II) have been synthesized from 6-formyl-7,8-dihydroxy-4-methylcoumarin with o-toluidine/3-aminobenzotrifluoride. The synthesized Schiff bases and their metal complexes were structurally characterized based on IR, 1H NMR, 13C NMR, UV-visible, ESR, magnetic, thermal, fluorescence, mass and ESI-MS studies. The molar conductance values indicate that complexes are non-electrolytic in nature. Elemental analysis reveals ML2·2H2O [M = Co(II), Ni(II) and Cu(II)] stoichiometry, where 'L' stands for a singly deprotonated ligand. The presence of co-ordinated water molecules were confirmed by thermal studies. The spectroscopic studies suggest the octahedral geometry. Redox behavior of the complexes were confirmed by cyclic voltammetry. All the synthesized compounds were screened for their antibacterial (Escherichia coli, Pseudomonas auregenosa, klebsiella, Proteus, Staphylococcus aureus and salmonella) antifungal (Candida, Aspergillus niger and Rhizopus), anthelmintic (Pheretima posthuma) and DNA cleavage (Calf Thymus DNA) activity.

  14. DNA cleavage, antibacterial, antifungal and anthelmintic studies of Co(II), Ni(II) and Cu(II) complexes of coumarin Schiff bases: synthesis and spectral approach.

    PubMed

    Patil, Sangamesh A; Prabhakara, Chetan T; Halasangi, Bhimashankar M; Toragalmath, Shivakumar S; Badami, Prema S

    2015-02-25

    The metal complexes of Co(II), Ni(II) and Cu(II) have been synthesized from 6-formyl-7,8-dihydroxy-4-methylcoumarin with o-toluidine/3-aminobenzotrifluoride. The synthesized Schiff bases and their metal complexes were structurally characterized based on IR, (1)H NMR, (13)C NMR, UV-visible, ESR, magnetic, thermal, fluorescence, mass and ESI-MS studies. The molar conductance values indicate that complexes are non-electrolytic in nature. Elemental analysis reveals ML2·2H2O [M = Co(II), Ni(II) and Cu(II)] stoichiometry, where 'L' stands for a singly deprotonated ligand. The presence of co-ordinated water molecules were confirmed by thermal studies. The spectroscopic studies suggest the octahedral geometry. Redox behavior of the complexes were confirmed by cyclic voltammetry. All the synthesized compounds were screened for their antibacterial (Escherichia coli, Pseudomonas auregenosa, klebsiella, Proteus, Staphylococcus aureus and salmonella) antifungal (Candida, Aspergillus niger and Rhizopus), anthelmintic (Pheretima posthuma) and DNA cleavage (Calf Thymus DNA) activity.

  15. Neutronic and thermal-hydraulic analysis of new irradiation channels inside the Moroccan TRIGA Mark II research reactor core.

    PubMed

    Chham, E; El Bardouni, T; Benaalilou, K; Boukhal, H; El Bakkari, B; Boulaich, Y; El Younoussi, C; Nacir, B

    2016-10-01

    This study was conducted to improve the capacity of radioisotope production in the Moroccan TRIGA Mark II research reactor, which is considered as one of the most important applications of research reactors. The aim of this study is to enhance the utilization of TRIGA core in the field of neutron activation and ensure an economic use of the fuel. The main idea was to create an additional irradiation channel (IC) inside the core. For this purpose, three new core configurations are proposed, which differ according to the IC position in the core. Thermal neutron flux distribution and other neutronic safety parameters such as power peaking factors, excess reactivity, and control rods worth reactivity were calculated using the Monte Carlo N-Particle Transport (MCNP) code and neutron cross-section library based on ENDF/B-VII evaluation. The calculated thermal flux in the central thimble (CT) and in the added IC for the reconfigured core is compared with the thermal flux in the CT of the existing core, which is taken as a reference. The results show that all the obtained fluxes in CTs are very close to the reference value, while a remarkable difference is observed between the fluxes in the new ICs and reference. This difference depends on the position of IC in the reactor core. To demonstrate that the Moroccan TRIGA reactor could safely operate at 2MW, with new configurations based on new ICs, different safety-related thermal-hydraulic parameters were investigated. The PARET model was used in this study to verify whether the safety margins are met despite the new modifications of the core. The results show that it is possible to introduce new ICs safely in the reactor core, because the obtained values of the parameters are largely far from compromising the safety of the reactor.

  16. Early Endosomes Are Required for Major Histocompatiblity Complex Class II Transport to Peptide-loading Compartments

    PubMed Central

    Brachet, Valérie; Péhau-Arnaudet, Gérard; Desaymard, Catherine; Raposo, Graça; Amigorena, Sebastian

    1999-01-01

    Antigen presentation to CD4+ T lymphocytes requires transport of newly synthesized major histocompatibility complex (MHC) class II molecules to the endocytic pathway, where peptide loading occurs. This step is mediated by a signal located in the cytoplasmic tail of the MHC class II-associated Ii chain, which directs the MHC class II-Ii complexes from the trans-Golgi network (TGN) to endosomes. The subcellular machinery responsible for the specific targeting of MHC class II molecules to the endocytic pathway, as well as the first compartments these molecules enter after exit from the TGN, remain unclear. We have designed an original experimental approach to selectively analyze this step of MHC class II transport. Newly synthesized MHC class II molecules were caused to accumulate in the Golgi apparatus and TGN by incubating the cells at 19°C, and early endosomes were functionally inactivated by in vivo cross-linking of transferrin (Tf) receptor–containing endosomes using Tf-HRP complexes and the HRP-insoluble substrate diaminobenzidine. Inactivation of Tf-containing endosomes caused a marked delay in Ii chain degradation, peptide loading, and MHC class II transport to the cell surface. Thus, early endosomes appear to be required for delivery of MHC class II molecules to the endocytic pathway. Under cross-linking conditions, most αβIi complexes accumulated in tubules and vesicles devoid of γ-adaptin and/or mannose-6-phosphate receptor, suggesting an AP1-independent pathway for the delivery of newly synthesized MHC class II molecules from the TGN to endosomes. PMID:10473634

  17. Collapse and fragmentation of magnetic molecular cloud cores with the Enzo AMR MHD code. II. Prolate and oblate cores

    SciTech Connect

    Boss, Alan P.; Keiser, Sandra A.

    2014-10-10

    We present the results of a large suite of three-dimensional models of the collapse of magnetic molecular cloud cores using the adaptive mesh refinement code Enzo2.2 in the ideal magnetohydrodynamics approximation. The cloud cores are initially either prolate or oblate, centrally condensed clouds with masses of 1.73 or 2.73 M {sub ☉}, respectively. The radial density profiles are Gaussian, with central densities 20 times higher than boundary densities. A barotropic equation of state is used to represent the transition from low density isothermal phases, to high density optically thick phases. The initial magnetic field strength ranges from 6.3 to 100 μG, corresponding to clouds that are strongly to marginally supercritical, respectively, in terms of the mass to magnetic flux ratio. The magnetic field is initially uniform and aligned with the clouds' rotation axes, with initial ratios of rotational to gravitational energy ranging from 10{sup –4} to 0.1. Two significantly different outcomes for collapse result: (1) formation of single protostars with spiral arms, and (2) fragmentation into multiple protostar systems. The transition between these two outcomes depends primarily on the initial magnetic field strength, with fragmentation occurring for mass to flux ratios greater than about 14 times the critical ratio for prolate clouds. Oblate clouds typically fragment into several times more clumps than prolate clouds. Multiple, rather than binary, system formation is the general rule in either case, suggesting that binary stars are primarily the result of the orbital dissolution of multiple protostar systems.

  18. Neutron scattering studies and modeling of high mobility group 14 core nucleosome complex

    SciTech Connect

    Uberbacher, E.C.; Mardian, J.K.; Rossi, R.M.; Olins, D.E.; Bunick, G.J.

    1982-09-01

    Considerable evidence relates the nonhistone proteins high mobility group (HMG) 14 and HMG 17 with the structure of active or potentially active chromatin. In this study, bulk nucleosome core particles prepared from chicken erythrocytes and the complex formed by binding two HMG 14 molecules per nucleosome core were studied by use of small-angle neutron scattering techniques. By varying the H/sub 2/O//sup 2/H/sub 2/O ratio, and hence the contrast between the solvent and the particles, it was possible to determine the radius of gyration of the protein and of the DNA independently and as a function of HMG 14 binding. The results show an increase of 0.9 +/- 0.6 angstrom (mean +/- SEM) in the protein radius of gyration and of 2.7 +/- 0.6 angstrom in the DNA radius of gyration upon binding of HMG 14 to the nucleosome. These changes are considered in the light of several postulated modes for the unfolding or perturbation of the nucleosome structure. Modeling calculations demonstrate that the observed changes in radius of gyration for the DNA and for the protein are too small to be consistent with an overall unfolding or opening of the core particle upon HMG 14 binding. However, the observed changes are consistent with several models that involve only minor changes in the structure. It is postulated that the differences observed may be an indication of the type of conformational changes occurring in active nucleosomes.

  19. Unified Microscopic-Macroscopic Monte Carlo Simulations of Complex Organic Molecule Chemistry in Cold Cores

    NASA Astrophysics Data System (ADS)

    Chang, Qiang; Herbst, Eric

    2016-03-01

    The recent discovery of methyl formate and dimethyl ether in the gas phase of cold cores with temperatures as cold as 10 K challenges our previous astrochemical models concerning the formation of complex organic molecules (COMs). The strong correlation between the abundances and distributions of methyl formate and dimethyl ether further shows that current astrochemical models may be missing important chemical processes in cold astronomical sources. We investigate a scenario in which COMs and the methoxy radical can be formed on dust grains via a so-called chain reaction mechanism, in a similar manner to CO2. A unified gas-grain microscopic-macroscopic Monte Carlo approach with both normal and interstitial sites for icy grain mantles is used to perform the chemical simulations. Reactive desorption with varying degrees of efficiency is included to enhance the nonthermal desorption of species formed on cold dust grains. In addition, varying degrees of efficiency for the surface formation of methoxy are also included. The observed abundances of a variety of organic molecules in cold cores can be reproduced in our models. The strong correlation between the abundances of methyl formate and dimethyl ether in cold cores can also be explained. Nondiffusive chemical reactions on dust grain surfaces may play a key role in the formation of some COMs.

  20. Antitumoral, antihypertensive, antimicrobial, and antioxidant effects of an octanuclear copper(II)-telmisartan complex with an hydrophobic nanometer hole.

    PubMed

    Islas, María S; Martínez Medina, Juan J; López Tévez, Libertad L; Rojo, Teófilo; Lezama, Luis; Griera Merino, Mercedes; Calleros, Laura; Cortes, María A; Rodriguez Puyol, Manuel; Echeverría, Gustavo A; Piro, Oscar E; Ferrer, Evelina G; Williams, Patricia A M

    2014-06-02

    A new Cu(II) complex with the antihypertensive drug telmisartan, [Cu8Tlm16]·24H2O (CuTlm), was synthesized and characterized by elemental analysis and electronic, FTIR, Raman and electron paramagnetic resonance spectroscopy. The crystal structure (at 120 K) was solved by X-ray diffraction methods. The octanuclear complex is a hydrate of but otherwise isostructural to the previously reported [Cu8Tlm16] complex. [Cu8Tlm16]·24H2O crystallizes in the tetragonal P4/ncc space group with a = b = 47.335(1), c = 30.894(3) Å, Z = 4 molecules per unit cell giving a macrocyclic ring with a double helical structure. The Cu(II) ions are in a distorted bipyramidal environment with a somewhat twisted square basis, cis-coordinated at their core N2O2 basis to two carboxylate oxygen and two terminal benzimidazole nitrogen atoms. Cu8Tlm16 has a toroidal-like shape with a hydrophobic nanometer hole, and their crystal packing defines nanochannels that extend along the crystal c-axis. Several biological activities of the complex and the parent ligand were examined in vitro. The antioxidant measurements indicate that the complex behaves as a superoxide dismutase mimic with improved superoxide scavenger power as compared with native sartan. The capacity of telmisartan and its copper complex to expand human mesangial cells (previously contracted by angiotensin II treatment) is similar to each other. The antihypertensive effect of the compounds is attributed to the strongest binding affinity to angiotensin II type 1 receptor and not to the antioxidant effects. The cytotoxic activity of the complex and that of its components was determined against lung cancer cell line A549 and three prostate cancer cell lines (LNCaP, PC-3, and DU 145). The complex displays some inhibitory effect on the A549 line and a high viability decrease on the LNCaP (androgen-sensitive) line. From flow cytometric analysis, an apoptotic mechanism was established for the latter cell line. Telmisartan and CuTlm show

  1. Electrocatalytic water oxidation using a chair-like tetranuclear copper(ii) complex in a neutral aqueous solution.

    PubMed

    Li, Ting-Ting; Zheng, Yue-Qing

    2016-08-09

    The development of viable molecular water oxidation catalysts is an important issue in the conversion of electricity or solar fuel into chemical fuels via water splitting, and copper complexes have become promising candidates for catalyzing water oxidation because of their low cost, well-defined redox properties and relatively high reactivity. Herein, we describe the first tetranuclear Cu(ii)-based water oxidation catalyst: [Cu4(bpy)4(μ2-OH)2(μ3-OH)2(H2O)2](2+). The complex comprises a chair-like Cu4O4 core with aqua and bridging μ-hydroxo ligands, and the multinuclear core is expected to be advantageous for promoting multi-electron transfer. In pH 7.0 phosphate buffer, the complex shows as being hydrolytically stable and a relatively low overpotential of ca. 730 mV is obtained according to a cyclic voltammetry experiment. Bulk electrolysis measurements at 1.80 V vs. a normal hydrogen electrode provided a stable current density of 0.78 mA cm(-2) and the current persists for at least 10 h. A Faradaic efficiency of nearly 98% is achieved. Importantly, the electrochemical data support that this tetranuclear complex works as a robust homogeneous water oxidation catalyst.

  2. Synthesis, structural and electrochemical properties of nickel(II) sulfamethazine complex with diethylenetriamine ligand.

    PubMed

    Bulut, İclal; Öztürk, Filiz; Bulut, Ahmet

    2015-03-05

    In this study, [Ni(dien)2]⋅smz2⋅(Hsmz: sulfamethazine and dien: diethylenetriamine) complex has been synthesized and its crystal structure has been determined by X-ray diffraction technique. The title complex crystallizes in orthorhombic system with space group Pbnb [a=8.556(5), b=16.228(5), c=28.209(5)Å, V=3917(3)Å(3) and Z=4]. The nickel(II) ion has distorted octahedral coordination geometry. The metal atom, which rides on a crystallographic center of symmetry, is coordinated by six nitrogen atoms of two dien ligands to form a discrete [Ni(dien)2](2+) unit, which captures two sulfamethazine ions, each through intermolecular hydrogen bonds. The powder EPR spectrum of Cu(2+) doped Ni(II) complex was recorded at room temperature. The vibrational investigation has been carried out by considering the characteristic bands related to the functional groups of the complex. The electrochemical behavior of Ni(II) ions in the presence and in the absence of smz and dien were studied by square wave and cyclic voltammetry. A well-defined irreversible peak at -1.112V different from those of the Ni(II)-smz (-0.876V) and the Ni(II)-dien complex (-1.064V) was observed in the solution containing Ni(II) ions, which was attributed to the formation of the new mixed ligand complex of Ni(II) with smz and dien.

  3. Synthesis, characterization, equilibrium study and biological activity of Cu(II), Ni(II) and Co(II) complexes of polydentate Schiff base ligand.

    PubMed

    El-Sherif, Ahmed A; Shehata, Mohamed R; Shoukry, Mohamed M; Barakat, Mohammad H

    2012-10-01

    Schiff base ligand, 1,4-bis[(2-hydroxybenzaldehyde)propyl]piperazine (BHPP), and its Cu(II), Ni(II) and Co(II) metal complexes were synthesized and characterized by elemental analysis, magnetic susceptibility, molar conductance and spectral (IR and UV-vis) studies. The ground state of BHPP ligand was investigated using the BUILDER module of MOE. Metal complexes are formed in the 1:1 (M:L) ratio as found from the elemental analysis and found to have the general formula [ML]·nH(2)O, where M=Co(II), Ni(II) and Cu(II), L=BHPP. In all the studied complexes, the (BHPP) ligand behaves as a hexadentate divalent anion with coordination involving the two azomethine nitrogen's, the two nitrogen atoms of piperazine ring and the two deprotonated phenolic OH-groups. The magnetic and spectral data indicates octahedral geometry of metal(II) complexes. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria and fungi. They were found to be more active against Gram-positive than Gram-negative bacteria. Protonation constants of (BHPP) ligand and stability constants of its Cu(2+), Co(2+) and Ni(2+) complexes were determined by potentiometric titration method in 50% DMSO-water solution at ionic strength of 0.1 M sodium nitrate. It has been observed that the protonated Schiff base ligand (BHPP) have four protonation constants. The divalent metal ions Cu(2+), Ni(2+) and Co(2+) form 1:1 complexes.

  4. Co(II), Ni(II) and Cu(II) complexes with coumarin-8-yl Schiff-bases: Spectroscopic, in vitro antimicrobial, DNA cleavage and fluorescence studies

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Unki, Shrishila N.; Kulkarni, Ajaykumar D.; Naik, Vinod H.; Badami, Prema S.

    2011-09-01

    A new series of Co(II), Ni(II) and Cu(II) complexes of the type ML·2H 2O of Schiff-bases derived from m-substituted thiosemicarbazides and 8-acetyl-7-hydroxy-4-methylcoumarin have been synthesized and characterized by spectroscopic studies. Schiff-bases exhibit thiol-thione tautomerism wherein sulphur plays an important role in the coordination. The coordination possibility of the Schiff-bases towards metal ions have been proposed in the light of elemental analyses, spectral (IR, UV-vis, FAB-mass, ESR and fluorescence), magnetic and thermal studies. The low molar conductance values in DMF indicate that, the metal complexes are non-electrolytes. The cyclic voltammetric studies suggested that, the Cu(II) and Ni(II) complexes are of single electron transfer quasi-reversible nature. The Schiff-bases and its metal complexes have been evaluated for their in vitro antibacterial ( Escherichia coli, Staphilococcus aureus, Bascillus subtilis and Salmonella typhi) and antifungal activities ( Candida albicans, Cladosporium and Aspergillus niger) by MIC method. The Schiff-base I and its metal complexes exhibited DNA cleavage activity on isolated DNA of A. niger.

  5. Co(II), Ni(II) and Cu(II) complexes with coumarin-8-yl Schiff-bases: spectroscopic, in vitro antimicrobial, DNA cleavage and fluorescence studies.

    PubMed

    Patil, Sangamesh A; Unki, Shrishila N; Kulkarni, Ajaykumar D; Naik, Vinod H; Badami, Prema S

    2011-09-01

    A new series of Co(II), Ni(II) and Cu(II) complexes of the type ML·2H2O of Schiff-bases derived from m-substituted thiosemicarbazides and 8-acetyl-7-hydroxy-4-methylcoumarin have been synthesized and characterized by spectroscopic studies. Schiff-bases exhibit thiol-thione tautomerism wherein sulphur plays an important role in the coordination. The coordination possibility of the Schiff-bases towards metal ions have been proposed in the light of elemental analyses, spectral (IR, UV-vis, FAB-mass, ESR and fluorescence), magnetic and thermal studies. The low molar conductance values in DMF indicate that, the metal complexes are non-electrolytes. The cyclic voltammetric studies suggested that, the Cu(II) and Ni(II) complexes are of single electron transfer quasi-reversible nature. The Schiff-bases and its metal complexes have been evaluated for their in vitro antibacterial (Escherichia coli, Staphilococcus aureus, Bascillus subtilis and Salmonella typhi) and antifungal activities (Candida albicans, Cladosporium and Aspergillus niger) by MIC method. The Schiff-base I and its metal complexes exhibited DNA cleavage activity on isolated DNA of A. niger.

  6. Magnetic interactions in CuII-LnIII cyclic tetranuclear complexes: is it possible to explain the occurrence of SMM behavior in CuII-TbIII and CuII-DyIII complexes?

    PubMed

    Hamamatsu, Takefumi; Yabe, Kazuya; Towatari, Masaaki; Osa, Shutaro; Matsumoto, Naohide; Re, Nazzareno; Pochaba, Andrzej; Mrozinski, Jerzy; Gallani, Jean-Louis; Barla, Alessandro; Imperia, Paolo; Paulsen, Carley; Kappler, Jean-Paul

    2007-05-28

    An extensive series of tetranuclear CuII2LnIII2 complexes [CuIILLnIII(hfac)2]2 (with LnIII being all lanthanide(III) ions except for the radioactive PmIII) has been prepared in order to investigate the nature of the CuII-LnIII magnetic interactions and to try to answer the following question: What makes the CuII2TbIII2 and CuII2DyIII2 complexes single molecule magnets while the other complexes are not? All the complexes within this series possess a similar cyclic tetranuclear structure, in which the CuII and LnIII ions are arrayed alternately via bridges of ligand complex (CuIIL). Regular SQUID magnetometry measurements have been performed on the series. The temperature-dependent magnetic susceptibilities from 2 to 300 K and the field-dependent magnetizations from 0 to 5 T at 2 K have been measured for the CuII2LnIII2 and NiII2LnIII2 complexes, with the NiII2LnIII2 complex containing diamagnetic NiII ions being used as a reference for the evaluation of the CuII-LnIII magnetic interactions. These measurements have revealed that the interactions between CuII and LnIII ions are very weakly antiferromagnetic if Ln=Ce, Nd, Sm, Yb, ferromagnetic if Ln=Gd, Tb, Dy, Ho, Er, Tm, and negligible if Ln=La, Eu, Pr, Lu. With the same goal of better understanding the evolution of the intramolecular magnetic interactions, X-ray magnetic circular dichroism (XMCD) has also been measured on CuII2TbIII2, CuII2DyIII2, and NiII2TbIII2 complexes, either at the L- and M-edges of the metal ions or at the K-edge of the N and O atoms. Last, the CuII2TbIII2 complex exhibiting SMM behavior has received a closer examination of its low temperature magnetic properties down to 0.1 K. These particular measurements have revealed the unusual very slow setting-up of a 3D order below 0.6 K.

  7. Synthesis, characterization, DFT calculations and biological studies of Mn(II), Fe(II), Co(II) and Cd(II) complexes based on a tetradentate ONNO donor Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Abdel-Rahman, Laila H.; Ismail, Nabawia M.; Ismael, Mohamed; Abu-Dief, Ahmed M.; Ahmed, Ebtehal Abdel-Hameed

    2017-04-01

    This study highlights synthesis and characterization of a tetradentate ONNO Schiff base ligand namely (1, 1‧- (pyridine-2, 3-dimethyliminomethyl) naphthalene-2, 2‧-diol) and hereafter denotes as "HNDAP″ and selected metal complexes including Mn(II), Fe(II), Co(II) and Cd(II) as a central metal. HNDAP was synthesized from 1:2 M ratio condensation of 2, 3-diaminopyridine and 2- hydroxy-1-naphthaldhyde, respectively. The stoichiometric ratios of the prepared complexes were estimated using complementary techniques such as; elemental analyses (-C, H, N), FT-IR, magnetic measurements and molar conductivity. Furthermore, their physicochemical studies were carried out using thermal TGA, DTA and kinetic-thermodynamic studies along with DFT calculations. The results of elemental analyses showed that these complexes are present in a 1:1 metal-to- ligand molar ratio. Moreover, the magnetic susceptibilities values at room temperature revealed that Mn(II), Fe(II) and Co(II) complexes are paramagnetic in nature and have an octahedral (Oh) geometry. In contrast, Cd(II) is diamagnetic and stabilizes in square planar sites. The molar conductivity measurements indicated that all complexes are nonelectrolytes in dimethyl formamide. Spectral data suggested that the ligand is as tetradentate and coordinated with Co(II) ion through two phenolic OH and two azomethine nitrogen. However, for Mn(II), Fe(II) and Cd(II) complexes, the coordination occurred through two phenolic oxygen and two azomethine nitrogen with deprotonation of OH groups. The proposed chemical structures have been validated by quantum mechanics calculations. Antimicrobial activities of both the HNDAP Schiff base ligand and its metal complexes were tested against strains of Gram (-ve) E. coli and Gram (+ve) B. subtilis and S. aureus bacteria and C. albicans, A. flavus and T. rubrum fungi. All the prepared compounds showed good results of inhibition against the selected pathogenic microorganisms. The investigated

  8. North Atlantic Simulations in Coordinated Ocean-Ice Reference Experiments Phase II (CORE-II) . Part II; Inter-Annual to Decadal Variability

    NASA Technical Reports Server (NTRS)

    Danabasoglu, Gokhan; Yeager, Steve G.; Kim, Who M.; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Bleck, Rainer; Boening, Claus; Bozec, Alexandra; Canuto, Vittorio M.; Howard, Armando M.; Kelley, Maxwell

    2015-01-01

    Simulated inter-annual to decadal variability and trends in the North Atlantic for the 1958-2007 period from twenty global ocean - sea-ice coupled models are presented. These simulations are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The study is Part II of our companion paper (Danabasoglu et al., 2014) which documented the mean states in the North Atlantic from the same models. A major focus of the present study is the representation of Atlantic meridional overturning circulation (AMOC) variability in the participating models. Relationships between AMOC variability and those of some other related variables, such as subpolar mixed layer depths, the North Atlantic Oscillation (NAO), and the Labrador Sea upper-ocean hydrographic properties, are also investigated. In general, AMOC variability shows three distinct stages. During the first stage that lasts until the mid- to late-1970s, AMOC is relatively steady, remaining lower than its long-term (1958-2007) mean. Thereafter, AMOC intensifies with maximum transports achieved in the mid- to late-1990s. This enhancement is then followed by a weakening trend until the end of our integration period. This sequence of low frequency AMOC variability is consistent with previous studies. Regarding strengthening of AMOC between about the mid-1970s and the mid-1990s, our results support a previously identified variability mechanism where AMOC intensification is connected to increased deep water formation in the subpolar North Atlantic, driven by NAO-related surface fluxes. The simulations tend to show general agreement in their representations of, for example, AMOC, sea surface temperature (SST), and subpolar mixed layer depth variabilities. In particular, the observed variability of the North Atlantic SSTs is captured well by all models. These findings indicate that simulated variability and trends are primarily dictated by the atmospheric datasets which include

  9. North Atlantic simulations in Coordinated Ocean-ice Reference Experiments phase II (CORE-II). Part II: Inter-annual to decadal variability

    NASA Astrophysics Data System (ADS)

    Danabasoglu, Gokhan; Yeager, Steve G.; Kim, Who M.; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Bleck, Rainer; Böning, Claus; Bozec, Alexandra; Canuto, Vittorio M.; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Danilov, Sergey; Diansky, Nikolay; Drange, Helge; Farneti, Riccardo; Fernandez, Elodie; Fogli, Pier Giuseppe; Forget, Gael; Fujii, Yosuke; Griffies, Stephen M.; Gusev, Anatoly; Heimbach, Patrick; Howard, Armando; Ilicak, Mehmet; Jung, Thomas; Karspeck, Alicia R.; Kelley, Maxwell; Large, William G.; Leboissetier, Anthony; Lu, Jianhua; Madec, Gurvan; Marsland, Simon J.; Masina, Simona; Navarra, Antonio; Nurser, A. J. George; Pirani, Anna; Romanou, Anastasia; Salas y Mélia, David; Samuels, Bonita L.; Scheinert, Markus; Sidorenko, Dmitry; Sun, Shan; Treguier, Anne-Marie; Tsujino, Hiroyuki; Uotila, Petteri; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang; Yashayaev, Igor

    2016-01-01

    Simulated inter-annual to decadal variability and trends in the North Atlantic for the 1958-2007 period from twenty global ocean - sea-ice coupled models are presented. These simulations are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The study is Part II of our companion paper (Danabasoglu et al., 2014) which documented the mean states in the North Atlantic from the same models. A major focus of the present study is the representation of Atlantic meridional overturning circulation (AMOC) variability in the participating models. Relationships between AMOC variability and those of some other related variables, such as subpolar mixed layer depths, the North Atlantic Oscillation (NAO), and the Labrador Sea upper-ocean hydrographic properties, are also investigated. In general, AMOC variability shows three distinct stages. During the first stage that lasts until the mid- to late-1970s, AMOC is relatively steady, remaining lower than its long-term (1958-2007) mean. Thereafter, AMOC intensifies with maximum transports achieved in the mid- to late-1990s. This enhancement is then followed by a weakening trend until the end of our integration period. This sequence of low frequency AMOC variability is consistent with previous studies. Regarding strengthening of AMOC between about the mid-1970s and the mid-1990s, our results support a previously identified variability mechanism where AMOC intensification is connected to increased deep water formation in the subpolar North Atlantic, driven by NAO-related surface fluxes. The simulations tend to show general agreement in their temporal representations of, for example, AMOC, sea surface temperature (SST), and subpolar mixed layer depth variabilities. In particular, the observed variability of the North Atlantic SSTs is captured well by all models. These findings indicate that simulated variability and trends are primarily dictated by the atmospheric datasets which

  10. Molecular dinitrogen complexes of ruthenium(II) porphyrins

    SciTech Connect

    Camenzind, M.J.; James, B.R.; Dolphin, D.; Sparapany, J.W.; Ibers, J.A.

    1988-08-24

    The existence of both mono- and bis(nitrogen) complexes of ruthenium have been previously established. Details on a series of complexes are presented herein, and results of an x-ray crystallographic study of Ru(TMP) (THF) (N/sub 2/) are reported. 30 references, 4 tables.

  11. New Series of Dinuclear Ruthenium(II) Complexes Synthesized Using Photoisomerization for Efficient Water Oxidation Catalysis.

    PubMed

    Hirahara, Masanari; Nagai, Sho; Takahashi, Kosuke; Saito, Kenji; Yui, Tatsuto; Yagi, Masayuki

    2015-08-03

    A new series of proximal,proximal-[Ru2(tpy)2(L)XY](n+) (p,p-Ru2XY, tpy = 2,2':6',2″-terpyridine, L = 5-phenyl-2,8-di(2-pyridyl)-1,9,10-anthyridine, X and Y = other coordination sites) were synthesized using photoisomerization of a mononuclear complex. The p,p-Ru2XY complexes undergo unusual reversible bridge-exchange reactions to generate p,p-Ru2(μ-Cl), p,p-Ru2(μ-OH), and p,p-Ru2(OH)(OH2) with μ-Cl, μ-OH, as well as hydroxo and aquo ligands at X and Y sites of p,p-Ru2XY, respectively. The geometric and electronic structures of these complexes were characterized based on UV-vis and (1)H NMR spectra, X-ray crystallography, and density functional theory (DFT) calculations. (1)H NMR data showed C2 symmetry of p,p-Ru2(OH)(OH2) with the distorted L chelate and nonequivalence of two tpy ligands, in contrast to the C2v symmetry of p,p-Ru2(μ-Cl) and p,p-Ru2(μ-OH). However, irrespective of the lower symmetry, p,p-Ru2(OH)(OH2) is predominantly formed in neutral and weakly basic conditions due to the specially stabilized core structure by multiple hydrogen-bond interactions among aquo, hydroxo, and backbone L ligands. The electrochemical data suggested that p,p-Ru2(OH)(OH2) (Ru(II)-OH:Ru(II)-OH2) is oxidized to the Ru(III)-OH:Ru(III)-OH state at 0.64 V vs saturated calomel electrode (SCE) and further to Ru(IV)═O:Ru(IV)-OH at 0.79 V by successive 1-proton-coupled 2-electron processes at pH 7.0. The cyclic voltammogram data exhibited that the p,p-Ru2(OH)(OH2) complex works more efficiently for electrocatalytic water oxidation, compared with a similar mononuclear complex distal-[Ru(tpy)(L)OH2](2+) (d-RuOH2) and p,p-Ru2(μ-Cl) and p,p-Ru2(μ-OH), showing that the p,p-Ru2 core structure with aquo and hydroxo ligands is important for efficient electrocatalytic water oxidation. Bulk electrolysis of the p,p-Ru2(OH)(OH2) solution corroborated the electrocatalytic cycle involving the Ru(III)-OH:Ru(III)-OH state species as a resting state. The mechanistic insight into O-O bond

  12. Decreased Photosystem II Core Phosphorylation in a Yellow-Green Mutant of Wheat Showing Monophasic Fluorescence Induction Curve.

    PubMed Central

    Giardi, M. T.; Kucera, T.; Briantais, J. M.; Hodges, M.

    1995-01-01

    In the present work we study the regulation of the distribution of the phosphorylated photosystem II (PSII) core populations present in grana regions of the thylakoids from several plant species. The heterogeneous nature of PSII core phosphorylation has previously been reported (M.T. Giardi, F. Rigoni, R. Barbato [1992] Plant Physiol 100: 1948-1954; M.T. Giardi [1993] Planta 190: 107-113). The pattern of four phosphorylated PSII core populations in the grana regions appears to be ubiquitous in higher plants. In the dark, at least two phosphorylated PSII core populations are always detected. A mutant of wheat (Triticum durum) that shows monophasic room-temperature photoreduction of the primary quinone electron acceptor of PSII as measured by chlorophyll fluorescence increase in the presence and absence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea and by fluorescence upon flash illumination in intact leaves also lacks the usual distribution of phosphorylated PSII core populations. In this mutant, the whole PSII core population pattern is changed, probably due to altered threonine kinase activity, which leads to the absence of light-induced phosphorylation of CP43 and D2 proteins. The results, correlated to previous experiments in vivo, support the idea that the functional heterogeneity observed by fluorescence is correlated in part to the PSII protein phosphorylation in the grana. PMID:12228652

  13. A high-resolution study of complex organic molecules in hot cores

    NASA Astrophysics Data System (ADS)

    Calcutt, Hannah; Viti, Serena; Codella, Claudio; Beltrán, Maria T.; Fontani, Francesco; Woods, Paul M.

    2014-10-01

    We present the results of a line identification analysis using data from the IRAM Plateau de Bure Plateau de Bure Interferometer, focusing on six massive star-forming hot cores: G31.41+0.31, G29.96-0.02, G19.61-0.23, G10.62-0.38, G24.78+0.08A1 and G24.78+0.08A2. We identify several transitions of vibrationally excited methyl formate (HCOOCH3) for the first time in these objects as well as transitions of other complex molecules, including ethyl cyanide (C2H5CN), and isocyanic acid (HNCO). We also postulate a detection of one transition of glycolaldehyde (CH2(OH)CHO) in two new hot cores. We find G29.96-0.02, G19.61-0.23, G24.78+0.08A1 and G24.78+0.08A2 to be chemically very similar. G31.41+0.31, however, is chemically different: it manifests a larger chemical inventory and has significantly larger column densities. We suggest that it may represent a different evolutionary stage to the other hot cores in the sample, or it may surround a star with a higher mass. We derive column densities for methyl formate in G31.41+0.31, using the rotation diagram method, of 4 × 1017 cm-2 and a Trot of ˜170 K. For G29.96-0.02, G24.78+0.08A1 and G24.78+0.08A2, glycolaldehyde, methyl formate and methyl cyanide, all seem to trace the same material and peak at roughly the same position towards the dust emission peak. For G31.41+0.31, however, glycolaldehyde shows a different distribution to methyl formate and methyl cyanide and seems to trace the densest, most compact inner part of hot cores.

  14. Synthesis, characterization and xanthine oxidase inhibition of Cu(II)-chrysin complex.

    PubMed

    Lin, Suyun; Zeng, Li; Zhang, Guowen; Liao, Yijing; Gong, Deming

    2017-05-05

    Xanthine oxidase (XO) is a key enzyme catalyzing hypoxanthine to xanthine and then uric acid causing hyperuricemia. A Cu(II) complex of chrysin was synthesized and characterized by UV-vis absorption, Fourier transform infrared, nuclear magnetic resonance ((1)H NMR) and mass spectroscopy studies. The interaction of Cu(II)-complex with XO was investigated by spectroscopic methods and molecular simulation. The Cu(II)-chrysin complex exhibited a better inhibitory ability (IC50=0.82±0.034μM) against XO than its corresponding ligands chrysin and Cu(2+) in a mix-competitive manner. The binding affinity of Cu(II)-chrysin complex with XO was much higher than that of chrysin. The hydrogen bonds and van der Waals forces played main roles in the binding. Analysis of circular dichroism spectra indicated that the complex induced the conformational change of XO. The molecular simulation found that the Cu(II)-chrysin complex inserted into the active cavity of XO with Cu acting as a bridge, occupying the catalytic center of the enzyme to avoid entry of the substrate xanthine, leading to the inhibition of XO. This study may provide new insights into the inhibition mechanism of the Cu(II)-chrysin complex as a promising XO inhibitor and its potential application for the treatment of hyperuricemia.

  15. Low complexity MIMO method based on matrix transformation for few-mode multi-core optical transmission system

    NASA Astrophysics Data System (ADS)

    Pan, Xiaolong; Liu, Bo; Li, Li; Tian, Qinghua

    2016-07-01

    This paper proposes and demonstrates a low complexity multiple-input multiple-output (MIMO) equalization digital signal processing (DSP) method for the few mode multi-core (FMMC) fiber optical transmission system. The MIMO equalization algorithm offers adaptive equalization taps according to the degree of crosstalk in cores or modes, which eliminates the interference among different modes and cores in space division multiplexing (SDM) transmission system. Compared with traditional MIMO method, the proposed scheme has increased the convergence rate by 4 times and reduced the number of finite impulse response (FIR) filters by 55% when the numbers of mode and core are three.

  16. Haploinsufficiency for Core Exon Junction Complex Components Disrupts Embryonic Neurogenesis and Causes p53-Mediated Microcephaly

    PubMed Central

    Wang, Zefeng; Silver, Debra L.

    2016-01-01

    The exon junction complex (EJC) is an RNA binding complex comprised of the core components Magoh, Rbm8a, and Eif4a3. Human mutations in EJC components cause neurodevelopmental pathologies. Further, mice heterozygous for either Magoh or Rbm8a exhibit aberrant neurogenesis and microcephaly. Yet despite the requirement of these genes for neurodevelopment, the pathogenic mechanisms linking EJC dysfunction to microcephaly remain poorly understood. Here we employ mouse genetics, transcriptomic and proteomic analyses to demonstrate that haploinsufficiency for each of the 3 core EJC components causes microcephaly via converging regulation of p53 signaling. Using a new conditional allele, we first show that Eif4a3 haploinsufficiency phenocopies aberrant neurogenesis and microcephaly of Magoh and Rbm8a mutant mice. Transcriptomic and proteomic analyses of embryonic brains at the onset of neurogenesis identifies common pathways altered in each of the 3 EJC mutants, including ribosome, proteasome, and p53 signaling components. We further demonstrate all 3 mutants exhibit defective splicing of RNA regulatory proteins, implying an EJC dependent RNA regulatory network that fine-tunes gene expression. Finally, we show that genetic ablation of one downstream pathway, p53, significantly rescues microcephaly of all 3 EJC mutants. This implicates p53 activation as a major node of neurodevelopmental pathogenesis following EJC impairment. Altogether our study reveals new mechanisms to help explain how EJC mutations influence neurogenesis and underlie neurodevelopmental disease. PMID:27618312

  17. Core-Shell Coating Silicon Anode Interfaces with Coordination Complex for Stable Lithium-Ion Batteries.

    PubMed

    Zhou, Jinqiu; Qian, Tao; Wang, Mengfan; Xu, Na; Zhang, Qi; Li, Qun; Yan, Chenglin

    2016-03-02

    In situ core-shell coating was used to improve the electrochemical performance of Si-based anodes with polypyrrole-Fe coordination complex. The vast functional groups in the organometallic coordination complex easily formed hydrogen bonds when in situ modifying commercial Si nanoparticles. The incorporation of polypyrrole-Fe resulted in the conformal conductive coating surrounding each Si nanoparticle, not only providing good electrical connection to the particles but also promoting the formation of a stable solid-electrolyte-interface layer on the Si electrode surface, enhancing the cycling properties. As an anode material for Li-ion batteries, modified silicon powders exhibited high reversible capacity (3567 mAh/g at 0.3 A/g), good rate property (549.12 mAh/g at 12 A/g), and excellent cycling performance (reversible capacity of 1500 mAh/g after 800 cycles at 1.2 A/g). The constructed novel concept of core-shell coating Si particles presented a promising route for facile and large-scale production of Si-based anodes for extremely durable Li-ion batteries, which provided a wide range of applications in the field of energy storage of the renewable energy derived from the solar energy, hydropower, tidal energy, and geothermal heat.

  18. Two new oximate-bridged square-planar dinuclear nickel(II) complexes.

    PubMed

    Bera, Manindranath; Noll, Bruce C

    2007-12-01

    The synthesis and characterization of two new dinuclear nickel(II) complexes, namely bis{mu-3-[2-(dimethylamino)ethylimino]butan-2-one oximato}dinickel(II) bis(perchlorate) acetonitrile solvate, [Ni2(C8H16N3O)2](ClO4)2 x CH3CN, (I), and bis{mu-3-[2-(dimethylamino)ethylimino]-3-phenylpropan-2-one oximato}dinickel(II) bis(perchlorate), [Ni2(C13H18N3O)2](ClO4)2, (II), are reported. Single-crystal X-ray analyses of the complexes reveal that the nickel(II) ions are in square-planar N3O environments and form six-membered (NiNO)2 metallacycles. The cation in (II) possesses crystallographically imposed inversion symmetry.

  19. Synthesis of tetrahedral quasi-type-II CdSe-CdS core-shell quantum dots.

    PubMed

    Sugunan, Abhilash; Zhao, Yichen; Mitra, Somak; Dong, Lin; Li, Shanghua; Popov, Sergei; Marcinkevicius, Saulius; Toprak, Muhammet S; Muhammed, Mamoun

    2011-10-21

    Synthesis of colloidal nanocrystals of II-VI semiconductor materials has been refined in recent decades and their size dependent optoelectronic properties have been well established. Here we report a facile synthesis of CdSe-CdS core-shell heterostructures using a two-step hot injection process. Red-shifts in absorption and photoluminescence spectra show that the obtained quantum dots have quasi-type-II alignment of energy levels. The obtained nanocrystals have a heterostructure with a large and highly faceted tetrahedral CdS shell grown epitaxially over a spherical CdSe core. The obtained morphology as well as high resolution electron microscopy confirms that the tetrahedral shell have a zinc blende crystal structure. A phenomenological mechanism for the growth and morphology of the nanocrystals is discussed.

  20. Excitation dynamics of two spectral forms of the core complexes from photosynthetic bacterium Thermochromatium tepidum.

    PubMed

    Ma, Fei; Kimura, Yukihiro; Zhao, Xiao-Hui; Wu, Yi-Shi; Wang, Peng; Fu, Li-Min; Wang, Zheng-Yu; Zhang, Jian-Ping

    2008-10-01

    The intact core antenna-reaction center (LH1-RC) core complex of thermophilic photosynthetic bacterium Thermochromatium (Tch.) tepidum is peculiar in its long-wavelength LH1-Q(y) absorption (915 nm). We have attempted comparative studies on the excitation dynamics of bacteriochlorophyll (BChl) and carotenoid (Car) between the intact core complex and the EDTA-treated one with the Q(y) absorption at 889 nm. For both spectral forms, the overall Car-to-BChl excitation energy transfer efficiency is determined to be approximately 20%, which is considerably lower than the reported values, e.g., approximately 35%, for other photosynthetic purple bacteria containing the same kind of Car (spirilloxanthin). The RC trapping time constants are found to be 50 approximately 60 ps (170 approximately 200 ps) for RC in open (closed) state irrespective to the spectral forms and the wavelengths of Q(y) excitation. Despite the low-energy LH1-Q(y) absorption, the RC trapping time are comparable to those reported for other photosynthetic bacteria with normal LH1-Q(y) absorption at 880 nm. Selective excitation to Car results in distinct differences in the Q(y)-bleaching dynamics between the two different spectral forms. This, together with the Car band-shift signals in response to Q(y) excitation, reveals the presence of two major groups of BChls in the LH1 of Tch. tepidum with a spectral heterogeneity of approximately 240 cm(-1), as well as an alteration in BChl-Car geometry in the 889-nm preparation with respect to the native one.

  1. Cu(II) and Pd(II) complexes of water soluble O-carboxymethyl chitosan Schiff bases: Synthesis, characterization.

    PubMed

    Baran, Talat; Menteş, Ayfer

    2015-08-01

    This study reports the synthesis of two new water soluble O-carboxymethyl chitosan Schiff bases (OCMCS-5 and OCMCS-6a) and their Cu(II) and Pd(II) complexes. Characterizations of these complexes were carried out with FTIR, elemental analysis, (13)C CPMAS, UV-vis, magnetic moment and molar conductivity techniques. The degrees of substitution (DS) for OCMCS-5a and OCMCS-6a were determined to be 0.48 and 0.44 in elemental analysis. The solubility test revealed that OCMCS-5a and OCMCS-6a dissolved thoroughly in water. The surface morphologies of chitosan (CS), OCMCS-5a, OCMCS-6a and their complexes were studied with SEM-EDAX. Thermal stability of the synthesized compounds was evaluated by TG/DTG and their crystallinity values were investigated with powder X-ray diffraction. Cu(II) and Pd(II) contents of the complexes were estimated with ICP-OES. The characterization studies demonstrated that the thermal stability and crystallinity values of the OCMCS-5a and OCMCS-6a were lower than those of CS.

  2. Synthesis, characterization and in vitro antimicrobial studies of Co(II), Ni(II) and Cu(II) complexes derived from macrocyclic compartmental ligand

    NASA Astrophysics Data System (ADS)

    El-Gammal, O. A.; Bekheit, M. M.; El-Brashy, S. A.

    2015-02-01

    New Co(II), Ni(II) and Cu(II) complexes derived from tetradentate macrocyclic nitrogen ligand, (1E,4E,8E,12E)-5,8,13,16-tetramethyl-1,4,9,12-tetrazacyclohexadeca-4,8,12,16-tetraene (EDHDH) have been synthesized. The complexes have been characterized by elemental analysis, spectral (IR, UV-Vis, 1H NMR and ESR (for Cu(II) complex)) mass, and magnetic as well as thermal analysis measurements. The complexes afforded the formulae: [Cu(EDHDH)Cl2]·2EtOH and [M(EDHDH)X2]·nH2O where M = Co(II) and Ni(II), X = Cl- or OH-, n = 1,0, respectively. The data revealed an octahedral arrangement with N4 tetradentate donor sites in addition to two Cl atoms occupying the other two sites. ESR spectrum of Cu2+ complex confirmed the suggested geometry with values of a α2and β2 indicating that the in-plane σ-bonding and in-plane π-bonding are appreciably covalent, and are consistent with very strong σ-in-plane bonding in the complexes. The molecular modeling is drawn and showed the bond length, bond angle, chemical reactivity, energy components (kcal/mol) and binding energy (kcal/mol) for all the title compounds using DFT method. Also, the thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. Moreover, the in vitro antibacterial studies of all compounds screened against pathogenic bacteria (two Gram +ve and two Gram -ve) to assess their inhibiting potential. The assay indicated that the inhibition potential is metal ion dependent. The ligand, EDHDH, Co(II) and Cu(II) complexes exhibited a remarkable antibacterial activity against Streptococcus Pyogenes as Gram +ve and Proteus vulgaris as Gram -ve bacterial strains. On the other hand, Ni(II) complex revealed a moderate antibacterial activity against both Gram +ve organisms and no activity against Gram -ve bacterial strain.

  3. Characterization and electrochemical studies of Mn(II), Co(II), Ni(II) and Cu(II) complexes with 2-mercapto-3-substituted-quinazolin-4-one and 1,10-phenanthroline or ethylenediamine as ligands

    NASA Astrophysics Data System (ADS)

    Sawant, V. A.; Gotpagar, S. N.; Yamgar, B. A.; Sawant, S. K.; Kankariya, R. D.; Chavan, S. S.

    2009-04-01

    Some mixed ligand complexes of the type [M(L 1 or L 2)( phen or en)(H 2O)Cl], where M = Mn(II), Co(II), Ni(II) and Cu(II); HL 1 = 2-mercapto-quinazolin-4-one; HL 2 = 2-mercapto-3-phenyl-quinazolin-4-one; phen = 1,10-phenanthroline; en = ethylenediamine have been prepared. All complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility measurements, IR, UV-vis, ESR and powder X-ray diffraction studies. IR spectra of these complexes reveal that the complex formation occurred through both nitrogen and sulphur atoms. On the basis of electronic spectral data and magnetic susceptibility measurement octahedral geometry has been proposed for the complexes. The ESR spectral data of the Cu(II) complexes showed that the metal-ligand bonds have considerable covalent character. X-ray diffraction studies of Cu(II) complexes are used to elucidate the crystal structure. The electrochemical behaviour of mixed ligand Ni(II) complexes was studied which showed that complexes of phen appear at more positive potential as compared to those for corresponding en complexes.

  4. Characterization and electrochemical studies of Mn(II), Co(II), Ni(II) and Cu(II) complexes with 2-mercapto-3-substituted-quinazolin-4-one and 1,10-phenanthroline or ethylenediamine as ligands.

    PubMed

    Sawant, V A; Gotpagar, S N; Yamgar, B A; Sawant, S K; Kankariya, R D; Chavan, S S

    2009-04-01

    Some mixed ligand complexes of the type [M(L(1) or L(2))(phen or en)(H(2)O)Cl], where M=Mn(II), Co(II), Ni(II) and Cu(II); HL(1)=2-mercapto-quinazolin-4-one; HL(2)=2-mercapto-3-phenyl-quinazolin-4-one; phen=1,10-phenanthroline; en=ethylenediamine have been prepared. All complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility measurements, IR, UV-vis, ESR and powder X-ray diffraction studies. IR spectra of these complexes reveal that the complex formation occurred through both nitrogen and sulphur atoms. On the basis of electronic spectral data and magnetic susceptibility measurement octahedral geometry has been proposed for the complexes. The ESR spectral data of the Cu(II) complexes showed that the metal-ligand bonds have considerable covalent character. X-ray diffraction studies of Cu(II) complexes are used to elucidate the crystal structure. The electrochemical behaviour of mixed ligand Ni(II) complexes was studied which showed that complexes of phen appear at more positive potential as compared to those for corresponding en complexes.

  5. Insight into the Structure of Light Harvesting Complex II and its Stabilization in Detergent Solution

    SciTech Connect

    Cardoso, Mateus B; Smolensky, Dmitriy; Heller, William T; O'Neill, Hugh Michael

    2009-01-01

    The structure of spinach light-harvesting complex II (LHC II), stabilized in a solution of the detergent n-octyl-{beta}-d-glucoside (BOG), was investigated by small-angle neutron scattering (SANS). Physicochemical characterization of the isolated complex indicated that it was pure (>95%) and also in its native trimeric state. SANS with contrast variation was used to investigate the properties of the protein-detergent complex at three different H{sub 2}O/D{sub 2}O contrast match points, enabling the scattering properties of the protein and detergent to be investigated independently. The topological shape of LHC II, determined using ab initio shape restoration methods from the SANS data at the contrast match point of BOG, was consistent with the X-ray crystallographic structure of LHC II (Liu et al. Nature 2004 428, 287-292). The interactions of the protein and detergent were investigated at the contrast match point for the protein and also in 100% D{sub 2}O. The data suggested that BOG micelle structure was altered by its interaction with LHC II, but large aggregate structures were not formed. Indirect Fourier transform analysis of the LHC II/BOG scattering curves showed that the increase in the maximum dimension of the protein-detergent complex was consistent with the presence of a monolayer of detergent surrounding the protein. A model of the LHC II/BOG complex was generated to interpret the measurements made in 100% D{sub 2}O. This model adequately reproduced the overall size of the LHC II/BOG complex, but demonstrated that the detergent does not have a highly regular shape that surrounds the hydrophobic periphery of LHC II. In addition to demonstrating that natively structured LHC II can be produced for functional characterization and for use in artificial solar energy applications, the analysis and modeling approaches described here can be used for characterizing detergent-associated {alpha}-helical transmembrane proteins.

  6. Crystal structures of copper(II) chloride, copper(II) bromide, and copper(II) nitrate complexes with pyridine-2-carbaldehyde thiosemicarbazone

    SciTech Connect

    Chumakov, Yu. M.; Tsapkov, V. I.; Jeanneau, E.; Bairac, N. N.; Bocelli, G.; Poirier, D.; Roy, J.; Gulea, A. P.

    2008-09-15

    The crystal structures of chloro-(2-formylpyridinethiosemicarbazono)copper dimethyl sulfoxide solvate (I), bromo-(2-formylpyridinethiosemicarbazono)copper (II), and (2-formylpyridinethiosemicarbazono)copper(II) nitrate dimethyl sulfoxide solvate (III) are determined using X-ray diffraction. In the crystals, complexes I and II form centrosymmetric dimers in which the thiosemicarbazone sulfur atom serves as a bridge and occupies the fifth coordination site of the copper atom of the neighboring complex related to the initial complex through the center of symmetry. In both cases, the coordination polyhedron of the complexing ion is a distorted tetragonal bipyramid. Complex III in the crystal structure forms polymer chains in which the copper atom of one complex forms the coordination bond with the thicarbamide nitrogen atom of the neighboring complex. In this structure, the coordination polyhedron of the central atom is an elongated tetragonal bipyramid. It is established that complexes I-III at a concentration of 10{sup -5} mol/l selectively inhibit the growth of 60 to 90 percent of the cancer tumor cells of the human myeloid leukemia (HL-60).

  7. Synthesis and crystal structure of a dinuclear, monomeric Mn(II) p-semiquinonato complex.

    PubMed

    Nakamori, Harutaka; Matsumoto, Takahiro; Yatabe, Takeshi; Yoon, Ki-Seok; Nakai, Hidetaka; Ogo, Seiji

    2014-11-07

    Herein, we report the first crystal structure of a monomeric p-semiquinonato d-block complex and its reactivity toward dioxygen, closely associated with a biological system of an oxygen evolving centre of photosystem II.

  8. Synthesis and characterisation of platinum (II) salphen complex and its interaction with calf thymus DNA

    NASA Astrophysics Data System (ADS)

    Sukri, Shahratul Ain Mohd; Heng, Lee Yook; Karim, Nurul Huda Abd

    2014-09-01

    A platinum (II) salphen complex was synthesised by condensation reaction of 2,4-dihydroxylbenzaldehyde and o-phenylenediamine with potassium tetrachloroplatinate to obtain N,N'-Bis-4-(hydroxysalicylidene)-phenylenediamine-platinum (II). The structure of the complex was confirmed by 1H and 13C NMR spectroscopy, FTIR spectroscopy, CHN elemental analyses and ESI-MS spectrometry. The platinum (II) salphen complex with four donor atoms N2O2 from its salphen ligand coordinated to platinum (II) metal centre were determined. The binding mode and interaction of this complex with calf thymus DNA was determined by UV/Vis DNA titration and emission titration. The intercalation between the DNA bases by π-π stacking due to its square planar geometry and aromatic rings structures was proposed.

  9. An energetic comparison of different models for the oxygen evolving complex of photosystem II.

    PubMed

    Siegbahn, Per E M

    2009-12-30

    The computed total energy from a cluster model DFT calculation is used to discriminate between different suggested models for the oxygen evolving complex of photosystem II. The comparison between different structures rules out several suggestions. Only one suggested structure remains.

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

    ERIC Educational Resources Information Center

    Goff, Harold M.; And Others

    1982-01-01

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

  11. Synthesis and characterisation of platinum (II) salphen complex and its interaction with calf thymus DNA

    SciTech Connect

    Sukri, Shahratul Ain Mohd; Heng, Lee Yook; Karim, Nurul Huda Abd

    2014-09-03

    A platinum (II) salphen complex was synthesised by condensation reaction of 2,4-dihydroxylbenzaldehyde and o-phenylenediamine with potassium tetrachloroplatinate to obtain N,N′-Bis-4-(hydroxysalicylidene)-phenylenediamine-platinum (II). The structure of the complex was confirmed by {sup 1}H and {sup 13}C NMR spectroscopy, FTIR spectroscopy, CHN elemental analyses and ESI-MS spectrometry. The platinum (II) salphen complex with four donor atoms N{sub 2}O{sub 2} from its salphen ligand coordinated to platinum (II) metal centre were determined. The binding mode and interaction of this complex with calf thymus DNA was determined by UV/Vis DNA titration and emission titration. The intercalation between the DNA bases by π-π stacking due to its square planar geometry and aromatic rings structures was proposed.

  12. Spectral studies of copper(II) complexes of 6-(3-thienyl) pyridine-2-thiosemicarbazone

    SciTech Connect

    Mahjoub, Omima Abdalla; Farina, Yang

    2014-09-03

    Two novel copper(II) complexes [Cu(HL)Cl]Cl.H{sub 2}O (1) and [Cu(L)NO{sub 3}]Ðœ‡H{sub 2}O (2) of the three NNS donor thiosemicarbazone ligand 6-(3-thienyl) pyridine-2-thiosemicarbazone have been synthesized. The ligand and its copper(II) complexes were characterized by elemental analysis (C, H, N, and S), FT-IR, UV-visible, magnetic susceptibility and molar conductance. The thiosemicarbazone is present either as the thione form in complex 1 or as thiol form in complex 2 and is coordinated to copper(II) atom via the pyridine nitrogen atom, the azomethine nitrogen atom and the sulfur atom. The physicochemical and spectral data suggest square planar geometry for copper(II) atoms.

  13. A new family of trinuclear nickel(II) complexes as single-molecule magnets.

    PubMed

    Biswas, Rituparna; Ida, Yumi; Baker, Michael L; Biswas, Saptarshi; Kar, Paramita; Nojiri, Hiroyuki; Ishida, Takayuki; Ghosh, Ashutosh

    2013-03-18

    Three new trinuclear nickel (II) complexes with the general composition [Ni3 L3 (OH)(X)](ClO4 ) have been prepared in which X=Cl(-) (1), OCN(-) (2), or N3(-) (3) and HL is the tridentate N,N,O donor Schiff base ligand 2-[(3-dimethylaminopropylimino)methyl]phenol. Single-crystal structural analyses revealed that all three complexes have a similar Ni3 core motif with three different types of bridging, namely phenoxido (μ2 and μ3 ), hydroxido (μ3 ), and μ2 -Cl (1), μ1,1 -NCO (2), or μ1,1 -N3 (3). The nickel(II) ions adopt a compressed octahedron geometry. Single-crystal magnetization measurements on complex 1 revealed that the pseudo-three-fold axis of Ni3 corresponds to a magnetic easy axis, being consistent with the magnetic anisotropy expected from the coordination structure of each nickel ion. Temperature-dependent magnetic measurements indicated ferromagnetic coupling leading to an S=3 ground state with 2J/k=17, 17, and 28 K for 1, 2, and 3, respectively, with the nickel atoms in an approximate equilateral triangle. The high-frequency EPR spectra in combination with spin Hamiltonian simulations that include zero-field splitting parameters DNi /k=-5, -4, and -4 K for 1, 2, and 3, respectively, reproduced the EPR spectra well after a anisotropic exchange term was introduced. Anisotropic exchange was identified as Di,j /k=-0.9, -0.8, and -0.8 K for 1, 2, and 3, respectively, whereas no evidence of single-ion rhombic anisotropy was observed spectroscopically. Slow relaxation of the magnetization at low temperatures is evident from the frequency-dependence of the out-of-phase ac susceptibilities. Pulsed-field magnetization recorded at 0.5 K shows clear steps in the hysteresis loop at 0.5-1 T, which has been assigned to quantum tunneling, and is characteristic of single-molecule magnets.

  14. Microwave-assisted synthesis of water-dispersed CdTe/CdSe core/shell type II quantum dots.

    PubMed

    Sai, Li-Man; Kong, Xiang Yang

    2011-05-27

    A facile synthesis of mercaptanacid-capped CdTe/CdSe (core/shell) type II quantum dots in aqueous solution by means of a microwave-assisted approach is reported. The results of X-ray diffraction and high-resolution transmission electron microscopy revealed that the as-prepared CdTe/CdSe quantum dots had a core/shell structure with high crystallinity. The core/shell quantum dots exhibit tunable fluorescence emissions by controlling the thickness of the CdSe shell. The photoluminescent properties were dramatically improved through UV-illuminated treatment, and the time-resolved fluorescence spectra showed that there is a gradual increase of decay lifetime with the thickness of CdSe shell.

  15. Optical and electronic properties of type-II CdSe/CdS core-shell quantum dots

    NASA Astrophysics Data System (ADS)

    Lee, Dea Uk; Yun, Dong Yeol; Kim, Tae Whan; Park, Seoung-Hwan; Choi, Donghyeuk; Kim, Sang Wook; Yoo, Keon-Ho; Lee, Hong Seok; Hae Kwon, Young; Kang, Tae Won

    2015-06-01

    CdSe/CdS core-shell quantum dots (QDs) were synthesized using a facile method in aqueous phase. X-ray diffraction pattern, high-resolution transmission electron microscopy images, and energy dispersive spectroscopy profiles showed that stoichiometric CdSe/CdS QDs were formed. Temperature-dependent photoluminescence spectra showed that the activation energy of CdSe/CdS core-shell QDs was 15 meV. The potential profiles and interband transition energies of the strained type-II CdSe/CdS core-shell QDs were calculated. The calculated interband transition energies slightly decreased from 2.061 to 2.007 eV when the shell thickness increased from 10 to 17 Å. The theoretical interband transition energy of 2.007 eV was in reasonable agreement with the photoluminescence excitonic transition energy of 1.98 eV.

  16. Synthesis and studies of a water-soluble and air-stable Cu(I)/Cu(II) open-shell funnel complex.

    PubMed

    Thiabaud, Grégory; Brugnara, Andrea; Carboni, Michael; Le Poul, Nicolas; Colasson, Benoît; Le Mest, Yves; Reinaud, Olivia

    2012-05-18

    The derivatization of the large rim of a TMPA-capped calix[6]arene (TMPA = tris(2-pyridylmethyl)amine) with three trimethylammonium groups enables the water-solubilization of two air-stable Cu(I)/Cu(II) complexes. These two complexes present a vacant coordination site shielded from the aqueous environment by the calixarene core. The spectroscopic and electrochemical data recorded in pure water indicate that the host-guest properties of the funnel complex are retained in both oxidation states of the copper cation.

  17. Transient photocyclization in ruthenium(ii) polypyridine complexes of indolamines.

    PubMed

    Carrone, G; Zayat, L; Slep, L D; Etchenique, R

    2017-01-18

    Ruthenium polypyridine complexes have proved to be useful caging groups for visible-light photodelivery of biomolecules. In most photoreactions, one ligand is expelled upon irradiation, yielding ruthenium mono-aqua complexes and no other photoproduct. In this work we show that a long-lived transient photoproduct is generated when the ruthenium complexes involve indolamines. The spatial conformation of this species is compatible with a cyclic structure that contains both the amine and the normally non-coordinating aromatic ring coordinated to the ruthenium center.

  18. Exafs and comparative studies of copper (II) complexes

    NASA Astrophysics Data System (ADS)

    Mishra, A.; Mishra, S.

    2016-10-01

    The present paper deals with the synthesis of transition metal Schiff base complexes of copper by chemical root method. The synthesized metal complexes were characterized by Extended X-ray absorption fine structure (EXAFS) is a technique that has been used for determining the metal ligand bond length using conventional X-ray source and also by EXAFS analysis using IFEFFIT programming. Bond lengths determined from these data analysis methods are compared with the bond lengths obtained from LSS, Levy's and Lytle's methods. Bond lengths of the complexes are in good agreement obtained by theoretical and experimental method.

  19. INVESTIGATING THE DEAROMATIVE REARRANGEMENT OF BIARYL PHOSPHINE-LIGATED PD(II) COMPLEXES

    PubMed Central

    Milner, Phillip J.; Maimone, Thomas J.; Su, Mingjuan; Chen, Jiahao; Müller, Peter; Buchwald, Stephen L.

    2012-01-01

    A series of monoligated L•PdII(Ar)X complexes (L = dialkyl biarylphosphine) have been prepared and studied in an effort to better understand an unusual dearomative rearrangement previously documented in these systems. Experimental and theoretical evidence suggest a concerted process involving the unprecedented PdII-mediated insertion of an aryl group into an unactivated arene. PMID:23153301

  20. Possible origin and significance of extension-parallel drainages in Arizona's metamophic core complexes

    USGS Publications Warehouse

    Spencer, J.E.

    2000-01-01

    The corrugated form of the Harcuvar, South Mountains, and Catalina metamorphic core complexes in Arizona reflects the shape of the middle Tertiary extensional detachment fault that projects over each complex. Corrugation axes are approximately parallel to the fault-displacement direction and to the footwall mylonitic lineation. The core complexes are locally incised by enigmatic, linear drainages that parallel corrugation axes and the inferred extension direction and are especially conspicuous on the crests of antiformal corrugations. These drainages have been attributed to erosional incision on a freshly denuded, planar, inclined fault ramp followed by folding that elevated and preserved some drainages on the crests of rising antiforms. According to this hypothesis, corrugations were produced by folding after subacrial exposure of detachment-fault foot-walls. An alternative hypothesis, proposed here, is as follows. In a setting where preexisting drainages cross an active normal fault, each fault-slip event will cut each drainage into two segments separated by a freshly denuded fault ramp. The upper and lower drainage segments will remain hydraulically linked after each fault-slip event if the drainage in the hanging-wall block is incised, even if the stream is on the flank of an antiformal corrugation and there is a large component of strike-slip fault movement. Maintenance of hydraulic linkage during sequential fault-slip events will guide the lengthening stream down the fault ramp as the ramp is uncovered, and stream incision will form a progressively lengthening, extension-parallel, linear drainage segment. This mechanism for linear drainage genesis is compatible with corrugations as original irregularities of the detachment fault, and does not require folding after early to middle Miocene footwall exhumations. This is desirable because many drainages are incised into nonmylonitic crystalline footwall rocks that were probably not folded under low

  1. Design, synthesis and characterization of macrocyclic ligand based transition metal complexes of Ni(II), Cu(II) and Co(II) with their antimicrobial and antioxidant evaluation

    NASA Astrophysics Data System (ADS)

    Gull, Parveez; Malik, Manzoor Ahmad; Dar, Ovas Ahmad; Hashmi, Athar Adil

    2017-04-01

    Three new complexes Ni(II), Cu(II) and Co(II) were synthesized of macrocyclic ligand derived from 1, 4-dicarbonyl-phenyl-dihydrazide and O-phthalaldehyde in the ratio of 2:2. The synthesized compounds were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV-Vis., Mass and 1H NMR spectral studies. The electronic spectra of the metal complexes indicate a six coordinate octahedral geometry of the central metal ion. These metal complexes and the ligand were evaluated for antimicrobial activity against bacteria (E. coli, B. subtilis, S. aureus) and fungi (A. niger, A. flavus, C. albicans) and compared against standard drugs chloramphenicol and nystatin respectively. In addition, the antioxidant activity of the compounds was also investigated through scavenging effect on DPPH radicals.

  2. Synthesis, characterization, and anti-cancer activity of emodin-Mn(II) metal complex.

    PubMed

    Yang, Li; Tan, Jun; Wang, Bo-Chu; Zhu, Lian-Cai

    2014-12-01

    To synthesize and characterize a novel metal complex of Mn (II) with emodin, and evaluate its anti-cancer activity. The elemental analyses, IR, UV-vis, atomic absorption spectroscopy, TG-DSC, (1)H NMR, and (13)C NMR data were used to characterize the structure of the complex. The cytotoxicity of the complex against the human cancer cell lines HepG2, HeLa, MCF-7, B16, and MDA-MB-231 was tested by the MTT assay and flow cytometry. Emodin was coordinated with Mn(II) through the 9-C=O and 1-OH, and the general formula of the complex was Mn(II) (emodin)2·2H2O. In studies of the cytotoxicity, the complex exhibited significant activity, and the IC50 values of the complex against five cancer cell lines improved approximately three-fold compared with those of emodin. The complex could induce cell morphological changes, decrease the percentage of viability, and induce G0/G1 phase arrest and apoptosis in cancer cells. The coordination of emodin with Mn(II) can improve its anticancer activity, and the complex Mn(II) (emodin)2·2H2O could be studied further as a promising anticancer drug.

  3. Synthesis and supramolecular association of immobilized NCN-pincer platinum(II) complexes on hyperbranched polyglycerol supports.

    PubMed

    Stiriba, Salah-Eddine; Slagt, Martijn Q; Kautz, Holger; Klein Gebbink, Robertus J M; Thomann, Ralf; Frey, Holger; van Koten, Gerard

    2004-03-05

    Pertosylation of hyperbranched polyglycerol (M(n)=2000; M(w)/M(n)=1.3) followed by partial displacement of the tosyl groups with carboxylic acid functionalized NCN-pincer platinum(II) complexes [PtI-2,6-(NMe(2)CH(2))(2)C(6)H(2)-4-COOH], resulted in covalent attachment of the NCN-pincer complexes to the polyglycerol. These functionalized hyperbranched macromolecules have been characterized by (1)H, (13)C, and (195)Pt NMR, UV-visible, and IR spectroscopy. The presence of Pt and I atoms renders them directly visible by transmission electron microscopy (TEM) without staining procedures, which offers images of associated hyperbranched macromolecules. TEM micrographs show disk-shaped structures with a small size-distribution (15-20 nm), and characteristic core-shell ring structures. The thickness of the corona observed in TEM could be correlated with the substitution degree with pincer platinum moieties.

  4. Structures of Thermoactinomyces vulgaris R-47 alpha-amylase II complexed with substrate analogues.

    PubMed

    Yokota, T; Tonozuka, T; Shimura, Y; Ichikawa, K; Kamitori, S; Sakano, Y

    2001-03-01

    The structures of Thermoactinomyces vulgaris R-47 alpha-amylase II mutant (d325nTVA II) complexed with substrate analogues, methyl beta-cyclodextrin (m beta-CD) and maltohexaose (G6), were solved by X-ray diffraction at 3.2 A and 3.3 A resolution, respectively. In d325nTVA II-m beta-CD complex, the orientation and binding-position of beta-CD in TVA II were identical to those in cyclodextin glucanotransferase (CGTase). The active site residues were essentialy conserved, while there are no residues corresponding to Tyr89, Phe183, and His233 of CGTase in TVA II. In d325nTVA II-G6 complex, the electron density maps of two glucosyl units at the non-reducing end were disordered and invisible. The four glucosyl units of G6 were bound to TVA II as in CGTase, while the others were not stacked and were probably flexible. The residues of TVA II corresponding to Tyr89, Lys232, and His233 of CGTase were completely lacking. These results suggest that the lack of the residues related to alpha-glucan and CD-stacking causes the functional distinctions between CGTase and TVA II.

  5. Insight into selectivity of peptidomimetic inhibitors with modified statine core for plasmepsin II of Plasmodium falciparum over human cathepsin D.

    PubMed

    Dali, Brice; Keita, Melalie; Megnassan, Eugene; Frecer, Vladimir; Miertus, Stanislav

    2012-04-01

    Plasmepsin II (PlmII), an aspartic protease expressed in the food vacuole of Plasmodium falciparum (pf), cleaves the hemoglobin of the host during the erythrocytic stage of the parasite life cycle. Various peptidomimetic inhibitors of PlmII reported so far discriminate poorly between the drug target and aspartic proteases of the host organism, e.g., human cathepsinD (hCatD). hCatD is a protein digestion enzyme and signaling molecule involved in a variety of physiological processes; therefore, inhibition of hCatD by PlmII inhibitors may lead to pathophysiological conditions. In this study, binding of PlmII inhibitors has been modeled using the crystal structures of pfPlmII and hCatD complexes to gain insight into structural requirements underlying the target selectivity. A series of 26 inhibitors were modeled in the binding clefts of the pfPlmII and hCatD to establish QSAR models of the protease inhibition. In addition, 3D-QSAR pharmacophore models were generated for each enzyme. It was concluded that the contributions of the P(2) and P(3') residues to the inhibitor's binding affinity are responsible for the target selectivity. Based on these findings, new inhibitor candidates were designed with predicted inhibition constants K (pre)(i PlmII) reaching 0.2nm and selectivity index (S.I.)=K(pre)(i PlmII) >1200.

  6. Isolation and spectroscopic characterization of Zn(II), Cu(II), and Pd(II) complexes of 1,3,4-thiadiazole-derived ligand

    NASA Astrophysics Data System (ADS)

    Karcz, Dariusz; Matwijczuk, Arkadiusz; Boroń, Bożena; Creaven, Bernadette; Fiedor, Leszek; Niewiadomy, Andrzej; Gagoś, Mariusz

    2017-01-01

    A series of complexes incorporating Zn(II), Cu(II), and Pd(II) ions, and 4-(5-heptyl-1,3,4-thiadiazol-2-yl)benzene-1,3-diol (L1) as model ligand, was synthesized in order to examine the nature of potential interactions between biologically active ligands, 1,3,4-thiadiazoles and metal ions with proven biological relevance. The structures of the compounds isolated were characterized using a number of spectroscopic methods including IR, Uv-vis, AAS, steady state and time-resolved fluorescence (TRF). The results obtained suggest that the L1-Zn(II) and L1-Pd(II) complexes consist of one molecule of L1 and one acetate ion acting as ligands, while the L1-Cu(II) complex adapts a 2:1 (L1: metal) stoichiometry. The coordination of L1 to metal ions occurs most likely via one of the deprotonated hydroxyl groups of the resorcinyl moiety and one of the N atoms of the thiadiazole heterocycle.

  7. Mesozoic burial, Mesozoic and Cenozoic exhumation of the Funeral Mountains core complex, Death Valley, Southeastern California

    NASA Astrophysics Data System (ADS)

    Beyene, Mengesha Assefa

    2011-12-01

    The Funeral Mountains of Death Valley National Park, CA, provide an opportunity to date metamorphism resulting from crustal shortening and subsequent episodic extensional events in the Sevier hinterland. It was not clear whether crustal shortening and thus peak temperature metamorphism in the hinterland of the Sevier-Laramide orogenic wedge have occurred whether in Late Jurassic, Early Cretaceous, Late Cretaceous or somewhere between. Particularly ambiguous is the timing of crustal shortening in the deep levels of the hinterland of the Sevier belt, now manifest in the metamorphic core complexes, and how and when these middle-to-lower crustal rocks were exhumed. A 6-point garnet and a whole rock Savillax isochron from middle greenschist facies pelitic schist of the southeastern Funeral Mountains core complex yields an age of 162.1 +/- 5.8 Ma (2sigma). Composite PT paths determined from growth-zoned garnets from the same samples show a nearly isothermal pressure increase of ˜2 kbar at ˜490°C, suggesting thrust burial at 162.1 +/- 5.8 Ma. A second sample of Johnnie Formation from the comparatively higher metamorphic grade area to the northwest (East of Chloride Cliff) yielded an age of 172.9 +/- 4.9 Ma (2sigma) suggesting an increase of thrust burial age towards the higher grade rocks (northwest part of the core complex), consistent with paleo-depth interpretation and metamorphic grade. 40Ar/ 39Ar muscovite ages along footwall of the Boundary Canyon detachment fault and intra-core Chloride Cliff shear zone exhibit significant 40Ar/39Ar muscovite age differences. For samples from the immediate footwall of BCD, the pattern of ages decreasing toward the northwest is consistent with differences in depth of metamorphism, and for Late Cretaceous, top-to-northwest exhumation by motion along the precursor BCD; consistent with mesoscopic and microscopic kinematic studies. Samples from the footwall of the structurally-lower Chloride Cliff shear zone yield Tertiary 40Ar/39Ar

  8. Cobalt(II) Ammine Complexes as Reversible Absorbers of Oxygen.

    ERIC Educational Resources Information Center

    Saito, Kazuo; Ogino, Kazuko

    1988-01-01

    Describes experiments designed to measure the oxygen content in the atmosphere and related areas in the high school laboratories. Considers the application of these activities to other programs. Includes a description of the binuclear complex and recommended procedures. (CW)

  9. Structural Determination of a Transcribing RNA Polymerase II Complex

    DTIC Science & Technology

    2000-05-01

    eukaryote- TFIIH, whose helicase activities melt DNA transcription initiation factor TFIIE, as re- specific subunits Rpbl0 and Rpbl2. Contact of...from a DNA template. Despite challenges involved in this project, a major achievement is at hand. Firstly, a mainchain model of RNA Polymerase II with...conducting research utilizing recombinant DNA technology, the investigator(s) adhered to current guidelines promulgated by the National Institutes of

  10. On Ohmic heating in the Earth's core II: Poloidal magnetic fields obeying Taylor's constraint

    NASA Astrophysics Data System (ADS)

    Jackson, Andrew; Livermore, Philip W.; Ierley, Glenn

    2011-08-01

    The extremely small Ekman and magnetic Rossby numbers in the Earth's core make the magnetostrophic limit an attractive approximation to the core's dynamics. This limit leads to the need for the internal magnetic field to satisfy Taylor's constraint, associated with the vanishing of the azimuthal component of Lorentz torques averaged over every cylinder coaxial with the rotation axis. A special class of three dimensional poloidal interior magnetic fields is chosen that satisfies Taylor's constraint identically on every cylinder in a spherical shell exterior to an inner core. This class of fields, which we call small-circle conservative, demonstrates existence of interior fields satisfying Taylor's constraint, regardless of the morphology of the field on the core surface. These poloidal fields are used to examine the Ohmic dissipation present in the Earth's core. To address the question of dissipation, we demand that the 3-D core fields agree with recent observations of the core field structure on the core-mantle boundary. We use these poloidal fields to show that the true lower bound on core dissipation must necessarily lie below a value that we calculate. For 2004 we find that this lower bound must lie below 10 10 W, and when nutation constraints are also considered the bound must lie below 2 × 10 10 W. These numbers are small compared to suggested values of the order of a few TeraWatts. A more restrictive bound may be forthcoming when the time-dependency of the field is considered, using a variational data assimilation technique.

  11. YOUNG STARLESS CORES EMBEDDED IN THE MAGNETICALLY DOMINATED PIPE NEBULA. II. EXTENDED DATA SET

    SciTech Connect

    Frau, P.; Girart, J. M.; Padovani, M.; Beltran, M. T.; Sanchez-Monge, A.; Busquet, G.; Morata, O.; Masque, J. M.; Estalella, R.; Alves, F. O.; Franco, G. A. P.

    2012-11-01

    The Pipe nebula is a massive, nearby, filamentary dark molecular cloud with a low star formation efficiency threaded by a uniform magnetic field perpendicular to its main axis. It harbors more than a hundred, mostly quiescent, very chemically young starless cores. The cloud is therefore a good laboratory to study the earliest stages of the star formation process. We aim to investigate the primordial conditions and the relation among physical, chemical, and magnetic properties in the evolution of low-mass starless cores. We used the IRAM 30 m telescope to map the 1.2 mm dust continuum emission of five new starless cores, which are in good agreement with previous visual extinction maps. For the sample of nine cores, which includes the four cores studied in a previous work, we derived an A {sub V} to N{sub H{sub 2}} factor of (1.27 {+-} 0.12) Multiplication-Sign 10{sup -21} mag cm{sup 2} and a background visual extinction of {approx}6.7 mag possibly arising from the cloud material. We derived an average core diameter of {approx}0.08 pc, density of {approx}10{sup 5} cm{sup -3}, and mass of {approx}1.7 M {sub Sun }. Several trends seem to exist related to increasing core density: (1) the diameter seems to shrink, (2) the mass seems to increase, and (3) the chemistry tends to be richer. No correlation is found between the direction of the surrounding diffuse medium magnetic field and the projected orientation of the cores, suggesting that large-scale magnetic fields seem to play a secondary role in shaping the cores. We also used the IRAM 30 m telescope to extend the previous molecular survey at 1 and 3 mm of early- and late-time molecules toward the same five new Pipe nebula starless cores, and analyzed the normalized intensities of the detected molecular transitions. We confirmed the chemical differentiation toward the sample and increased the number of molecular transitions of the 'diffuse' (e.g., the 'ubiquitous' CO, C{sub 2}H, and CS), 'oxo-sulfurated' (e.g., SO and

  12. The effect of peculiar complex core balance training on isokinetic muscle functions of the knee and lumbus

    PubMed Central

    Lee, Myungsun; Han, Gunsoo

    2016-01-01

    [Purpose] This study aimed to investigate the effect of peculiar complex core balance training on the isokinetic muscle function of the knee joint and lumbus to provide fundamental data for establishing a training program that focuses on improving the performance and prevention of injury by developing the core and low extremity muscles. [Subjects and Methods] The participants in this study included a total of ten high school athletes involved in a throwing event for over five years. The subjects were randomly divided into two groups: The experimental group (N=5) and the control group (N=5). The experimental group underwent peculiar complex core balance training. [Results] According to the analysis of covariance, there was a significant effect of peculiar complex core balance training. Therefore, the isokinetic muscle function of the knee joint and lumbus in the experimental group participating in peculiar complex core balance training was significantly increased compared to the control group. [Conclusion] It is concluded that peculiar complex core balance training had a positive effect on the isokinetic muscle function of the knee and lumbus in throwing event athletes. PMID:27190470

  13. The effect of peculiar complex core balance training on isokinetic muscle functions of the knee and lumbus.

    PubMed

    Lee, Myungsun; Han, Gunsoo

    2016-04-01

    [Purpose] This study aimed to investigate the effect of peculiar complex core balance training on the isokinetic muscle function of the knee joint and lumbus to provide fundamental data for establishing a training program that focuses on improving the performance and prevention of injury by developing the core and low extremity muscles. [Subjects and Methods] The participants in this study included a total of ten high school athletes involved in a throwing event for over five years. The subjects were randomly divided into two groups: The experimental group (N=5) and the control group (N=5). The experimental group underwent peculiar complex core balance training. [Results] According to the analysis of covariance, there was a significant effect of peculiar complex core balance training. Therefore, the isokinetic muscle function of the knee joint and lumbus in the experimental group participating in peculiar complex core balance training was significantly increased compared to the control group. [Conclusion] It is concluded that peculiar complex core balance training had a positive effect on the isokinetic muscle function of the knee and lumbus in throwing event athletes.

  14. META II Complex Systems Design and Analysis (CODA)

    DTIC Science & Technology

    2011-08-01

    the notion of graph energy as a matrix norm and as a plausible measure of complexity. The adjacency matrix n nA M  of a network is defined as...40  3.9  Software and mapping modeling .............................................................................. 40  3.9.1  Decision...diagram-based complexity of software models ................................. 40  3.10 Abstraction layers design

  15. Investigation of Detergent Effects on the Solution Structure of Spinach Light Harvesting Complex II

    SciTech Connect

    Cardoso, Mateus B; Smolensky, Dmitriy; Heller, William T; O'Neill, Hugh Michael

    2010-01-01

    The properties of spinach light harvesting complex II (LHC II), stabilized in the detergents Triton X-100 (TX100) and n-Octyl-{beta}-D-Glucoside (BOG), were investigated by small-angle neutron scattering (SANS). The LHC II-BOG scattering curve overlaid well with the theoretical scattering curve generated from the crystal structure of LHC II indicating that the protein preparation was in its native functional state. On the other hand, the simulated LHC II curve deviated significantly from the LHC II-TX100 experimental data. Analysis by circular dichroism spectroscopy supported the SANS analysis and showed that LHC II-TX100 is inactivated. This investigation has implications for extracting and stabilizing photosynthetic membrane proteins for the development of biohybrid photoconversion devices.

  16. Investigation of detergent effects on the solution structure of spinach Light Harvesting Complex II

    NASA Astrophysics Data System (ADS)

    Cardoso, Mateus B.; Smolensky, Dmitriy; Heller, William T.; O'Neill, Hugh

    2010-11-01

    The properties of spinach light harvesting complex II (LHC II), stabilized in the detergents Triton X-100 (TX100) and n-Octyl-β-D-Glucoside (BOG), were investigated by small-angle neutron scattering (SANS). The LHC II-BOG scattering curve overlaid well with the theoretical scattering curve generated from the crystal structure of LHC II indicating that the protein preparation was in its native functional state. On the other hand, the simulated LHC II curve deviated significantly from the LHC II-TX100 experimental data. Analysis by circular dichroism spectroscopy supported the SANS analysis and showed that LHC II-TX100 is inactivated. This investigation has implications for extracting and stabilizing photosynthetic membrane proteins for the development of biohybrid photoconversion devices.

  17. Synthesis, characterization, electrochemical and biological studies on some metal(II) Schiff base complexes containing quinoxaline moiety.

    PubMed

    Dhanaraj, Chellaian Justin; Johnson, Jijo

    2014-01-24

    Novel Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff base derived from quinoxaline-2,3-(1,4H)-dione and 4-aminoantipyrine (QDAAP) were synthesized. The ligand and its complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV-Vis., mass and (1)H NMR spectral studies. The X band ESR spectrum of the Cu(II) complex at 300 and 77K were also recorded. Thermal studies of the ligand and its complexes show the presence of coordinated water in the Ni(II) and Zn(II) complexes. The coordination behavior of QDAAP is also discussed. All the complexes are mono nuclear and tetrahedral geometry was found for Co(II) complex. For the Ni(II) and Zn(II) complexes, octahedral geometry was assigned and for the Cu(II) complex, square planar geometry has been suggested. The grain size of the complexes was estimated using powder XRD. The surface morphology of the compounds was studied using SEM analysis. Electrochemical behavior of the synthesized complexes in DMF at room temperature was investigated by cyclic voltammetry. The in vitro biological screening of QDAAP and its metal complexes were tested against bacterial species Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The fungal species include Aspergillus niger, Aspergillus flavus and Candida albicans. The DNA cleavage activity of QDAAP and its complexes were also discussed.

  18. Synthesis, characterization, electrochemical and biological studies on some metal(II) Schiff base complexes containing quinoxaline moiety

    NASA Astrophysics Data System (ADS)

    Justin Dhanaraj, Chellaian; Johnson, Jijo

    2014-01-01

    Novel Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff base derived from quinoxaline-2,3-(1,4H)-dione and 4-aminoantipyrine (QDAAP) were synthesized. The ligand and its complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV-Vis., mass and 1H NMR spectral studies. The X band ESR spectrum of the Cu(II) complex at 300 and 77 K were also recorded. Thermal studies of the ligand and its complexes show the presence of coordinated water in the Ni(II) and Zn(II) complexes. The coordination behavior of QDAAP is also discussed. All the complexes are mono nuclear and tetrahedral geometry was found for Co(II) complex. For the Ni(II) and Zn(II) complexes, octahedral geometry was assigned and for the Cu(II) complex, square planar geometry has been suggested. The grain size of the complexes was estimated using powder XRD. The surface morphology of the compounds was studied using SEM analysis. Electrochemical behavior of the synthesized complexes in DMF at room temperature was investigated by cyclic voltammetry. The in vitro biological screening of QDAAP and its metal complexes were tested against bacterial species Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The fungal species include Aspergillus niger, Aspergillus flavus and Candida albicans. The DNA cleavage activity of QDAAP and its complexes were also discussed.

  19. Cu(II), Ni(II), and Zn(II) Complexes of Salan-Type Ligand Containing Ester Groups: Synthesis, Characterization, Electrochemical Properties, and In Vitro Biological Activities

    PubMed Central

    Jeslin Kanaga Inba, P.; Annaraj, B.; Thalamuthu, S.; Neelakantan, M. A.

    2013-01-01

    A salen ligand on reduction and N-alkylation affords a novel [N2O2] chelating ligand containing ester groups [L = diethyl-2,2′-(propane-1,3-diylbis((2-hydroxy-3-methoxy benzyl)azanediyl))diacetate]. The purity of the ligand was confirmed by NMR and HPLC chromatograms. Its Cu(II), Ni(II), and Zn(II) complexes were synthesized and characterized by a combination of elemental analysis, IR, NMR, UV-Vis, and mass spectral data, and thermogravimetric analysis (TG/DTA). The magnetic moments, UV-Vis, and EPR spectral studies support square planar geometry around the Cu(II) and Ni(II) ions. A tetrahedral geometry is observed in four-coordinate zinc with bulky N-alkylated salan ligand. The redox properties of the copper complex were examined in DMSO by cyclic voltammetry. The voltammograms show quasireversible process. The interaction of metal complexes with CT DNA was investigated by UV-Vis absorption titration, ethidium bromide displacement assay, cyclic voltammetry methods, and agarose gel electrophoresis. The apparent binding constant values suggest moderate intercalative binding modes between the complexes and DNA. The in vitro antioxidant and antimicrobial potentials of the synthesized compounds were also determined. PMID:23983672

  20. Synthesis of thin film containing 4-amino-1,2,4-triazole iron(II) complexes

    SciTech Connect

    Onggo, Djulia

    2014-03-24

    The Iron(II) complex with 4-amino-1,2,4 triazole (NH{sub 2}-trz) ligand has potential applications as smart material since the compounds show a distinct color change from lilac at low temperature to colorless at high temperature. The lilac color of the complex represent the diamagnetic low spin state while the colorless correspond to the paramagnetic high spin state of iron(II). The transition between the two states could be tuned by changing the anionic group. Generally, the complex was synthesized directly from aqueous solution of iron(II) salt with considerable amounts of NH{sub 2}-trz solution produced solid powder compound. For application as an electronic molecular device, the complex should be obtained as a thin film. The transparent [Fe(NH{sub 2}trz){sub 3}]-Nafion film has been successfully obtained, however, no anion variation can be produced since the nafion is an anionic resin. In this work, the [Fe(NH{sub 2}trz){sub 3}]-complexes with several anions have been synthesized inside nata de coco membrane that commonly used as a medium for deposition metal nano-particles. After drying the membrane containing the complex became a thin film. At room temperature, the film containing iron(II) complexes of sulphate and nitrate salts show lilac color, similar to that of the original complexes in the powder form. On heating, the color of the complex film changed to colorless and this color change was observed reversibly. In contrast, the films containing perchlorate and tetrafluoroborate iron(II) complexes are colorless at room temperature and changed to lilac on cooling. The significant color changing of the iron(II)complexes in the nata de coco film can be used for demonstration thermo chromic effect of smart materials with relatively small amount of the compounds.

  1. Synthesis and vibrational study of platinum(II) and palladium(II) complexes of glyoxilic acid oxime

    NASA Astrophysics Data System (ADS)

    Trendafilova, N.; Bauer, G.; Georgieva, I.; Dodoff, N.

    1999-12-01

    New platinum(II) and palladium(II) complexes of glyoxilic acid oxime (gao) have been prepared and characterised by infrared (4000-150 cm -1) and Raman (4000-200 cm -1) spectra. The gao acts as bidentate ligand bonding through the oxime nitrogen and carboxyl oxygen atoms to form neutral bis-chelate square-planar complexes. The lowest energy conformer of the gao ligand ( ectt) was selected among 16 theoretically possible conformers on the basis of ab initio calculations at HF/3-21G*, HF/6-31G* and HF/6-311** levels of the theory from which structural parameters and conformational stabilities have been obtained. A complete vibrational assignment of the gao was performed for the lowest energy ectt conformer on the basis of ab initio optimised parameters and normal coordinate analysis calculations (PED). NCA calculations of the complexes studied were also performed.

  2. Complexation facilitated reduction of aromatic N-oxides by aqueous Fe(II)-tiron complex: reaction kinetics and mechanisms.

    PubMed

    Chen, Yiling; Zhang, Huichun

    2013-10-01

    Rapid reduction of carbadox (CDX), olaquindox and several other aromatic N-oxides were investigated in aqueous solution containing Fe(II) and tiron. Consistent with previous work, the 1:2 Fe(II)-tiron complex, FeL2(6-), is the dominant reactive species as its concentration linearly correlates with the observed rate constant kobs under various conditions. The N-oxides without any side chains were much less reactive, suggesting direct reduction of the N-oxides is slow. UV-vis spectra suggest FeL2(6-) likely forms 5- or 7-membered rings with CDX and olaquindox through the N and O atoms on the side chain. The formed inner-sphere complexes significantly facilitated electron transfer from FeL2(6-) to the N-oxides. Reduction products of the N-oxides were identified by HPLC/QToF-MS to be the deoxygenated analogs. QSAR analysis indicated neither the first electron transfer nor N-O bond cleavage is the rate-limiting step. Calculations of the atomic spin densities of the anionic N-oxides confirmed the extensive delocalization between the aromatic ring and the side chain, suggesting complex formation can significantly affect the reduction kinetics. Our results suggest the complexation facilitated N-oxide reduction by Fe(II)-tiron involves a free radical mechanism, and the subsequent deoxygenation might also benefit from the weak complexation of Fe(II) with the N-oxide O atom.

  3. Hydrolysis and cytotoxic properties of osmium(II)/(III)-DMSO-azole complexes. Short communication.

    PubMed

    Egger, Alexander; Cebrián-Losantos, Berta; Stepanenko, Iryna N; Krokhin, Artem A; Eichinger, Rene; Jakupec, Michael A; Arion, Vladimir B; Keppler, Bernhard K

    2008-08-01

    The antiproliferative properties of the osmium(II) complexes cis,fac-[Os(II)Cl(2)(DMSO)(3)(L)] and trans,cis,cis-[Os(II)Cl(2)(DMSO)(2)(L)(2)] (L = 1H-pyrazole, 1H-imidazole) were studied in three human cancer cell lines, namely 41M (ovary), SK-BR-3 (breast), and SW480 (colon). Their activities were compared with those of osmium(III) and ruthenium(III) NAMI-A type complexes on HT-29 (colon) and SK-BR-3 cancer cell lines. While IC(50) values of all the Os(II) complexes were found to be >1000 microM in all cell lines, Os and Ru-NAMI-A type complexes showed remarkable antiproliferative activity. The marginal in vitro cytotoxicity of the Os(II) compounds is presumably attributed to their resistance to hydrolysis. However, the Os-NAMI-A complexes, which are also kinetically stable in aqueous solution, showed reasonable antiproliferative activity in vitro when compared with the analogous Ru compounds and with the Os(II)-DMSO-azole species, indicating that hydrolysis might be not a prerequisite for the antitumor activity of Os-NAMI-A type complexes.

  4. Decomposition of reactive oxygen species by copper(II) bis(1-pyrazolyl)methane complexes.

    PubMed

    Schepetkin, Igor; Potapov, Andrei; Khlebnikov, Andrei; Korotkova, Elena; Lukina, Anna; Malovichko, Galina; Kirpotina, Lilia; Quinn, Mark T

    2006-06-01

    Two bis(1-pyrazolyl)alkane ligands, bis(3,5-dimethyl-1-pyrazolyl)methane and bis(4-iodo-3,5-dimethyl-1-pyrazolyl)methane, and their copper(II) complexes, bis(3,5-dimethyl-1-pyrazolyl)methanedinitratocopper(II) [CuL1(NO3)2] and bis(4-iodo-3,5-dimethyl-1-pyrazolyl)methanedinitratocopper(II) [CuL2(NO3)2] x 2H2O, were prepared. Physiochemical properties of the copper(II) complexes were studied by spectroscopic (UV-vis, IR, EPR) techniques and cyclic voltammetry. Spectroscopic analysis revealed a 1:1 stoichiometry of ligand:copper(II) ion and a bidentate coordination mode for the nitrate ions in both of the complexes. According to experimental and theoretical ab initio data, the copper(II) ion is located in an octahedral hexacoordinated environment. Both complexes were able to catalyze the dismutation of superoxide anion (O2*-) (pH 7.5) and decomposition of H2O2 (pH 7.5) and peroxynitrite (pH 10.9). In addition, both complexes exhibited superoxide dismutase (SOD) like activity toward extracellular and intracellular reactive oxygen species produced by activated human neutrophils in whole blood. Thus, these complexes represent useful SOD mimetics with a broad range of antioxidant activity toward a variety of reactive oxidants.

  5. Structural studies on some dithiophosphonato complexes of Ni(II), Cd(II), Hg(II) and theoretical studies on a dithiophosphonato Ni(II) complex using density functional theory

    NASA Astrophysics Data System (ADS)

    Sağlam, Ertuğrul Gazi; Ebinç, Ahmet; Zeyrek, Celal Tuğrul; Ünver, Hüseyin; Hökelek, Tuncer

    2015-11-01

    In this study, three dithiophosphonic acid complexes, namely, trans-bis-[O-3-methylbutyl (4-methoxyphenyl)dithiophosphonato]nickel(II), Ni(L)2; bis-{bis-[O-3-phenylpropyl (4-methoxyphenyl)dithiophosphonato]cadmium(II)}, [Cd(L)2]2 and bis-{bis-[O-3-methylbutyl (4-methoxyphenyl)dithiophosphonato]mercury(II)}, [Hg(L)2]2 were prepared. The compounds were characterized by elemental analysis; MS; FTIR and Raman spectroscopies and were also investigated by 1H-, 13C- and 31P- NMR. The Ni(L)2 complex was elucidated by X-ray crystallography, molecular characterization and density functional modelling studies. The molecular structure obtained from X-ray single-crystal analysis of the Ni(L)2 complex in the ground state has been compared using density functional theory (DFT), B3LYP functional with 6-311G(d,p) basis set. In addition to the optimized geometrical structures, atomic charges and nonlinear optical (NLO) effects have been investigated by using DFT. The experimental (spectroscopic) and calculated vibrational frequencies (using DFT) of the Ni(L)2 have been compared. There exists a good correlation between experimental and theoretical data for the Ni(L)2 complex.

  6. Mono-nuclear copper complexes mimicking the intermediates for the binuclear copper center of the subunit II of cytochrome oxidase: a peptide based approach.

    PubMed

    Dutta Gupta, Dwaipayan; Usharani, Dandamudi; Mazumdar, Shyamalava

    2016-11-28

    Three stable copper complexes of peptides derived from the copper ion binding loop of the subunit II of cytochrome c oxidase have been prepared and characterized by various spectroscopic techniques. These stable copper complexes of peptides were found to exhibit cysteine, histidine and/or methionine ligation, which has predominant σ-contribution in the Cys-Cu charge transfer. The copper(ii) peptide complexes showed type-2 EPR spectra, which is uncommon in copper-cysteinate complexes. UV-visible spectra, Raman and EPR results support a tetragonal structure of the coordination geometry around the copper ion. The copper complex of the 9-amino acid peptide suggested the formation of a 'red' copper center while the copper complexes of the 12- and 11-amino acid peptides showed the formation of a 'green' copper center. The results provide insights on the first stable models of the copper complexes formed in the peptide scaffold that mimic the mono-nuclear copper bound protein intermediates proposed during the formation of the binuclear Cu2S2 core of the enzyme. These three copper complexes of peptides derived from the metal ion binding loop of the CuA center of the subunit II of cytochrome c oxidase showed novel spectroscopic properties which have not so far been reported in any stable small complex.

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

    PubMed

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

    2010-11-01

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

  8. Characteristic differences in the formation of complex coacervate core micelles from neodymium and zinc-based coordination polymers.

    PubMed

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

    2007-05-31

    In this paper we compare the formation of complex coacervate core micelles (C3Ms) from two different tricompontent mixtures, namely neodymium, the bisligand L2EO4 and the poly(cation)-block-poly(neutral) diblock copolymer P2MVP41-b-PEO205, and zinc, L2EO4 and P2MVP41-b-PEO205 mixed systems. Three sets of titration experiments were carried out for each system: (i) titration of diblock copolymer P2MVP41-b-PEO205 with the stoichiometric mixture of metal ions and bisligands, (ii) titration of a mixture of diblock copolymer and bisligand with metal ions, and (iii) titration of a mixture of diblock copolymer and metal ions with bisligands. In all the above three cases, micelles are found to form either in a broad range of charge ratios or in a broad range of metal/bisligand ratios. Upon addition of Nd2-(L2EO4)3 coordination polymer to P2MVP41-b-PEO205 solution, and upon addition of Nd3+ to a mixture of L2EO4 and P2MVP41-b-PEO205, micelles are found to form immediately after the first addition, whereas micelles show up in the similar zinc system only after a certain threshold Zn-(L2EO4) or Zn2+ concentration. This difference can be traced to the different structures of the Nd2-(L2EO4)3 and Zn-(L2EO4) coordination compounds. At very low concentrations, Zn-(L2EO4) are ring-like oligomers, but Nd2-(L2EO4)3 are larger networks. The network structure favors the formation of coacervate micellar core with P2MVP41-b-PEO205. Moreover, excess of Nd3+ ions will break up the C3Ms, while the same amount of Zn2+ has hardly any effect on the C3Ms. The breakdown of C3Ms by Nd3+ is due to the charge inversion of the coordination complex with increasing [Nd3+]/[L2EO4] ratio, which results in repulsive interaction between the coordination complex and the diblock copolymer, whereas no such interaction can occur in the zinc system.

  9. Reaction of beta-diketiminate copper(II) complexes and Na2S2.

    PubMed

    Inosako, Masayuki; Kunishita, Atsushi; Shimokawa, Chizu; Teraoka, Junji; Kubo, Minoru; Ogura, Takashi; Sugimoto, Hideki; Itoh, Shinobu

    2008-11-28

    Reaction of beta-diketiminate copper(II) complexes and Na2S2 resulted in formation of (mu-eta2:eta2-disulfido)dicopper(II) complexes (adduct formation) or beta-diketiminate copper(I) complexes (reduction of copper(II)) depending on the substituents of the supporting ligands. In the case of sterically less demanding ligands, adduct formation occurred to provide the (mu-eta2:eta2-disulfido)dicopper(II) complexes, whereas reduction of copper(II) took place to give the corresponding copper(I) complexes with sterically more demanding beta-diketiminate ligands. Spectroscopic examinations of the reactions at low temperature using UV-vis and ESR as well as kinetic analysis have suggested that a 1 : 1 adduct LCuII-S-SNa with an end-on binding mode is initially formed as a common intermediate, from which different reaction pathways exist depending on the steric environment of the metal-coordination sphere provided by the ligands. Thus, with the sterically less demanding ligands, rearrangement of the disulfide adduct from end-on to side-on followed by self-dimerisation occurs to give the (mu-eta2:eta2-disulfido)dicopper(II) complexes, whereas such an intramolecular rearrangement of the disulfide co-ligand does not take place with the sterically more demanding ligands. In this case, homolytic cleavage of the CuII-S bond occurs to give the reduced copper(I) product. The steric effects of the supporting ligands have been discussed on the basis of detailed analysis of the crystal structures of the copper(II) starting materials.

  10. Spectroscopic (FT-IR, FT-Raman, 1H, 13C NMR, UV/VIS), thermogravimetric and antimicrobial studies of Ca(II), Mn(II), Cu(II), Zn(II) and Cd(II) complexes of ferulic acid

    NASA Astrophysics Data System (ADS)

    Kalinowska, M.; Piekut, J.; Bruss, A.; Follet, C.; Sienkiewicz-Gromiuk, J.; Świsłocka, R.; Rzączyńska, Z.; Lewandowski, W.

    2014-03-01

    The molecular structure of Mn(II), Cu(II), Zn(II), Cd(II) and Ca(II) ferulates (4-hydroxy-3-methoxycinnamates) was studied. The selected metal ferulates were synthesized. Their composition was established by means of elementary and thermogravimetric analysis. The following spectroscopic methods were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance (13C, 1H NMR) and ultraviolet-visible (UV/VIS). On the basis of obtained results the electronic charge distribution in studied metal complexes in comparison with ferulic acid molecule was discussed. The microbiological study of ferulic acid and ferulates toward Escherichia coli, Bacillus subtilis, Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris was done.

  11. Synthesis of dihydromyricetin-manganese (II) complex and interaction with DNA

    NASA Astrophysics Data System (ADS)

    Guo, Qingquan; Yuan, Juan; Zeng, Jinhua; He, Xiangzhu; Li, Daguang

    2012-11-01

    Dihydromyricetin has many physiological functions and its metal complex could have better effects. DNA is very important in biological body, but little attention has been devoted to the relationship between dihydromyricetin-metal complex and the DNA. In this paper, dihydromyricetin-Mn (II) complex has been prepared and characterized using UV-vis absorption spectrophotometry, IR spectroscopy, elemental analysis, and thermal gravimetric analysis (TG-DTA Analysis). The interaction of dihydromyricetin-Mn (II) complex with DNA was investigated using UV-vis spectra, fluorescence measurements and viscosity measurements. The results indicate that the dihydromyricetin-manganese (II) complex can intercalate into the stacked base pairs of DNA with binding constant Kb = 5.64 × 104 M and compete with the strong intercalator ethidium bromide for the intercalative binding sites with Stern-Volmer quenching constant, Ksq = 1.16.

  12. Synthesis and Antiproliferative Activity of Steroidal Thiosemicarbazone Platinum (Pt(II)) Complexes

    PubMed Central

    Huang, Yanmin; Kong, Erbin; Gan, Chunfang; Liu, Zhiping; Lin, Qifu; Cui, Jianguo

    2015-01-01

    Steroidal compounds exhibit particular physiological activities. In this paper, some steroidal thiosemicarbazones platinum (Pt(II)) complexes were synthesized by the condensation of steroidal ketones with thiosemicarbazide using estrone, chenodeoxycholic acid, and 7-deoxycholic acid as starting materials and complexation of steroidal thiosesemicarbazones with Pt(II). The complexes were characterized by IR, NMR, and MS, and their antiproliferative activities were evaluated. The results showed that some steroidal thiosemicarbazones platinum (Pt(II)) complexes displayed moderate cytotoxicity to HeLa and Bel-7404 cells. Thereinto, complex 6 showed an excellent inhibited selectivity to HeLa cells with an IC50 value of 9.2 μM and SI value of 21.7. At the same time, all compounds were almost inactive to HEK293T (normal kidney epithelial cells). The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs. PMID:26635511

  13. Cyclometalated NCN platinum(II) acetylide complexes - Synthesis, photophysics and OLEDs fabrication

    NASA Astrophysics Data System (ADS)

    Szafraniec-Gorol, Grazyna; Slodek, Aneta; Schab-Balcerzak, Ewa; Grucela, Marzena; Siwy, Mariola; Filapek, Michal; Matussek, Marek; Zych, Dawid; Mackowski, Sebastian; Buczynska, Dorota; Grzelak, Justyna; Erfurt, Karol; Chrobok, Anna; Krompiec, Stanislaw

    2016-12-01

    The novel cyclometalated NCN platinum(II) acetylide complexes were synthesized. As precursors of acetylide ligands were used 9,9-dibutyl-2-ethynylfluorene, 9-butyl-3-ethynylcarbazole, and 5-ethynyl-2,2‧-bithiophene, whereas 1,3-di(2-pirydyl)benzene derivatives were cyclometalating NCN ligands. Variable character of ligands allowed to prepare a series of novel platinum(II) complexes, which showed light emission in a wide wavelength range from 410 to 625 nm. The optical and electrochemical properties of new complexes were examined and compared with theoretical DFT calculations. Complexes containing fluorenyl and carbazyl motif were used as emitters in an organic light-emitting diodes. The applicability of these Pt(II) complexes for electroluminescence was examined.

  14. Synthesis of Dipyridyl Ketone Isonicotinoyl Hydrazone Copper(II) Complex: Structure, Anticancer Activity and Anticancer Mechanism.

    PubMed

    Deng, JunGang; Chen, Wei; Deng, Hang

    2016-11-01

    In an effort to better understand the biological efficacy of the tridentate aroyl hydrazone Cu(II) complexes, the Cu(II) complex of di-2-pyridyl ketone isonicotinoyl hydrazone ligand (HL), {[Cu(L)(H2O)]·H2O·NO3}n (C1) was synthesized and characterized. Single crystal X-ray study reveals that complex C1 forms 1D zigzag chains in solid state. In water, the hydrolysis of the 1D zigzag chains was observed, and finally formation of monomeric species. In vitro studies revealed that complex C1 showed significantly more anticancer activity than the ligand alone. Investigation of the anticancer mechanisms of C1, confirmed that the Cu(II) complex exhibit a strong capacity to promote productions of reactive oxygen species (ROS), leading to caspase-dependent apoptotic cell death.

  15. Synthesis, spectral, thermal and magnetic studies of Mn(II), Ni(II) and Cu(II) complexes with some benzopyran-4-one Schiff bases.

    PubMed

    el-Ansary, Aida L; Abdel-Fattah, Hussein M; Abdel-Kader, Nora S

    2011-08-01

    The Schiff bases of N(2)O(2) dibasic ligands, H(2)La and H(2)Lb are prepared by the condensation of ethylenediamine (a) and trimethylenediamine (b) with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one. Also tetra basic ligands, H(4)La and H(4)Lb are prepared by the condensation of aliphatic amines (a) and (b) with 6-formyl-5,7-dihydroxy-2-methylbenzopyran-4-one. New complexes of H(4)La and H(4)Lb with metal ions Mn(II), Ni(II) and Cu(II) are synthesized, in addition Mn(II) complexes with ligands H(2)La and H(2)Lb are also synthesized. Elemental and thermal analyses, infrared, ultraviolet-visible as well as conductivity and magnetic susceptibility measurements are used to elucidate the structure of the newly prepared metal complexes. The structures of copper(II) complexes are also assigned based upon ESR spectra study. All the complexes separated with the stoichiometric ratio (1:1) (M:L) except Mn-H(4)La and Mn-H(4)Lb with (2:1) (M:L) molar ratio. In metal chelates of the type 1:1 (M:L), the Schiff bases behave as a dinegative N(2)O(2) tetradentate ligands. Moreover in 2:1 (M:L) complexes, the Schiff base molecules act as mono negative bidentate ligand and binuclear complex is then formed. The Schiff bases were assayed by the disc diffusion method for antibacterial activity against Staphylococcus aureus and Escherichia coli. The antifungal activity of the Schiff bases was also evaluated against the fungi Aspergillus flavus and Candida albicans.

  16. Structural, spectroscopic and quantum chemical studies of acetyl hydrazone oxime and its palladium(II) and platinum(II) complexes

    NASA Astrophysics Data System (ADS)

    Kaya, Yunus; Icsel, Ceyda; Yilmaz, Veysel T.; Buyukgungor, Orhan

    2015-09-01

    Acetyl hydrazone oxime, [(1E,2E)-2-(hydroxyimino)-1-phenylethylidene]acetohydrazone (hipeahH2) and its palladium(II) and platinum(II) complexes, [M(hipeahH)2] (M = PdII and PtII), have been synthesized and characterized by elemental analysis, UV-vis IR, NMR and LC-MS techniques. X-ray diffraction analysis of [Pd(hipeahH)2] shows that the two hipeahH2 ligands are not equal; one of the ligands loses the hydrazone proton, while the other one loses the oxime proton, resulting in a different coordination behavior to form five- and six-membered chelate rings. The molecular geometries from X-ray experiments in the ground state were compared using the density functional theory (DFT) with the B3LYP method combined with the 6-311++G(d,p) basis set for the ligand and the LanL2DZ basis set for the complexes. Comprehensive theoretical and experimental structural studies on the molecule have been carried out by FT-IR, NMR and UV-vis spectrometry. In addition, the isomer studies of ligand and its complexes were made by DFT.

  17. Possible giant metamorphic core complex at the center of Artemis Corona, Venus

    USGS Publications Warehouse

    Spencer, J.E.

    2001-01-01

    Hundreds of circular features on Venus known as coronae are characterized by annular fractures and commonly associated radial fractures and lava flows. Coronae are thought to have been produced by buoyant mantle diapirs that flatten and spread at the base of the lithosphere and cause fracturing, uplift, and magmatism. The interior of Artemis Corona, by far the largest corona at 2100 km diameter, is divided in half by a northeast-trending deformation belt that contains numerous rounded ridges resembling antiforms. The largest of these ridges, located at the center of Artemis Corona, is ???5 km high on its steep northwest flank where it is adjacent to a flat-bottomed, 10-km-wide trough interpreted as a rift valley. The 280-km-long antiformal ridge is marked by perpendicular grooves that cross the ???50-km-wide ridge and extend southeastward as far as 120 km across adjacent plains. The grooves abruptly terminate northwestward at the rift trough. The large antiformal ridge terminates southwestward at a transform shear zone that parallels the grooves. These features-rift valley, antiformal uplift, grooves, and transform shear zone-are morphologically and geometrically similar to grooved, elevated, submarine metamorphic core complexes on the inside corners of ridge-transform intersections of slow-spreading ridges on Earth. As with submarine core complexes, the grooved surface on Venus is interpreted as the footwall of a large-displacement normal fault, and the grooves are inferred to be the product of plastic molding of the footwall to irregularities on the underside of the hanging wall followed by tectonic exhumation of the molded grooves and conveyer-belt-like transport up and over the large antiform and across the southeastern plains. According to this interpretation, the trend of the grooves records the direction of extension, which is perpendicular to the thrusts at the leading edge of the annular thrust belt 1000 km to the southeast. Both may have formed at the

  18. Ductile strain rate recorded in the Symvolon syn-extensional plutonic body (Rhodope core complex, Greece)

    NASA Astrophysics Data System (ADS)

    Cirrincione, Rosolino; Fazio, Eugenio; Ortolano, Gaetano; Fiannacca, Patrizia; Kern, Hartmut; Mengel, Kurt; Pezzino, Antonino; Punturo, Rosalda

    2016-04-01

    The present contribution deals with quantitative microstructural analysis, which was performed on granodiorites of the syn-tectonic Symvolon pluton (Punturo et al., 2014) at the south-western boundary of the Rhodope Core Complex (Greece). Our purpose is the quantification of ductile strain rate achieved across the pluton, by considering its cooling gradient from the centre to the periphery, using the combination of a paleopiezometer (Shimizu, 2008) and a quartz flow law (Hirth et al., 2001). Obtained results, associated with a detailed cooling history (Dinter et al., 1995), allowed us to reconstruct the joined cooling and strain gradient evolution of the pluton from its emplacement during early Miocene (ca. 700°C at 22 Ma) to its following cooling stage (ca. 500-300°C at 15 Ma). Shearing temperature values were constrained by means of a thermodynamic approach based on the recognition of syn-shear assemblages at incremental strain; to this aim, statistical handling of mineral chemistry X-Ray maps was carried out on microdomains detected at the tails of porphyroclasts. Results indicate that the strain/cooling gradients evolve "arm in arm" across the pluton, as also testified by the progressive development of mylonitic fabric over the magmatic microstructures approaching the host rock. References • Dinter, D. A., Macfarlane, A., Hames, W., Isachsen, C., Bowring, S., and Royden, L. (1995). U-Pb and 40Ar/39Ar geochronology of the Symvolon granodiorite: Implications for the thermal and structural evolution of the Rhodope metamorphic core complex, northeastern Greece. Tectonics, 14 (4), 886-908. • Shimizu, I. (2008). Theories and applicability of grain size piezometers: The role of dynamic recrystallization mechanisms. Journal of Structural Geology, 30 (7), 899-917. • Hirth, G., Teyssier, C., and Dunlap, J. W. (2001). An evaluation of quartzite flow laws based on comparisons between experimentally and naturally deformed rocks. International Journal of Earth

  19. Subsidence in Gorontalo Bay, Sulawesi (Indonesia) and metamorphic core complex exhumation on land

    NASA Astrophysics Data System (ADS)

    Pezzati, Giovanni; Hennig, Juliane; Advokaat, Eldert; Hall, Robert; Burgess, Peter; Perez-Gussinye, Marta

    2015-04-01

    Gorontalo Bay is a semi-enclosed sea between the North and East Arms of Sulawesi. It is surrounded by land on three sides, separating a northern volcanic province from metamorphic rocks to the south and west, and ophiolites to the southeast. In the western part of Gorontalo Bay there are two sub-basins: the northern Tomini Basin and the southern Poso Basin, which have different histories. This study presents a new geological interpretation of western Gorontalo Bay, based on recent multibeam and 2D seismic data and field observations on land. In Tomini Basin six major seismic sequences (Units A to F) have a total thickness of more than 5 sec TWT. Ages are based on correlation with events on land. A major unconformity above Basement Unit A is interpreted to be the result of an Early Miocene collision. Unit A subsided from the Early Miocene, with deposition of Units B and C largely in a deep marine environment. There was regional uplift in the Middle Miocene followed by renewed subsidence resulting in shallow marine depositional environments in which carbonate platforms developed (Units D-E). Subsidence accelerated during the deposition of Unit E, causing back-stepping of the shelf edge, formation of pinnacle reefs and then drowning of the carbonate platforms, leading to the present depths of 2 km in the basin centre with a thin clastic cover (Unit F). North of Tomini Basin, the Malino Metamorphic Complex exposes strongly deformed mid-crustal rocks which record Middle Miocene extension accommodated by low angle shear zones. A second phase of rapid uplift and extension recorded in these rocks occurred in the Pliocene-Pleistocene, and was accommodated by high angle normal faulting. Poso Basin is younger than Tomini Basin and it occupies the southern part of western Gorontalo Bay. The deeper part of its sedimentary sequence is probably the time equivalent of Unit D in Tomini Basin. Immediately south of Poso Basin, on land, is a large metamorphic core complex. Seismic

  20. Synthesis, spectroscopic, fluorescence properties and biological evaluation of novel Pd(II) and Cd(II) complexes of NOON tetradentate Schiff bases.

    PubMed

    Ali, Omyma A M

    2014-01-01

    The solid complexes of Pd(II) and Cd(II) with N,N/bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H2L(1)), and N,N/bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H2L(2)) have been synthesized and characterized by several techniques using elemental analysis (CHN), FT-IR, (1)H NMR, UV-Vis spectra and thermal analysis. Elemental analysis data proved 1:1 stoichiometry for the reported complexes while spectroscopic data indicated square planar and octahedral geometries for Pd(II) and Cd(II) complexes, respectively. The prepared ligands, Pd(II) and Cd(II) complexes exhibited intraligand (π-π(∗)) fluorescence and can potentially serve as photoactive materials. Thermal behavior of the complexes was studied and kinetic parameters were determined by Coats-Redfern method. Both the ligands and their complexes have been screened for antimicrobial activities.

  1. Liquid-crystalline dendrimer Cu(II) complexes and Cu(0) nanoclusters based on the Cu(II) complexes: An electron paramagnetic resonance investigation

    NASA Astrophysics Data System (ADS)

    Domracheva, N. E.; Mirea, A.; Schwoerer, M.; Torre-Lorente, L.; Lattermann, G.

    2007-07-01

    New nanostructured materials, namely, the liquid-crystalline copper(II) complexes that contain poly(propylene imine) dendrimer ligands of the first (ligand 1) and second (ligand 2) generations and which have a columnar mesophase and different copper contents (x = Cu/L), are investigated by EPR spectroscopy. The influence of water molecules and nitrate counterions on the magnetic properties of complex 2 (x = 7.3) is studied. It is demonstrated that water molecules can extract some of the copper ions from dendrimer complexes and form hexaaqua copper complexes with free ions. The dimer spectra of fully hydrated complex 2 (x = 7.3) are observed at temperatures T < 10 K. For this complex, the structure is identified and the distance between the copper ions is determined. It is shown that the nitrate counterion plays the role of a bridge between the hexaaqua copper(II) complex and the dendrimer copper(II) complex. The temperature-induced valence tautomerism attended by electron transport is revealed for the first time in blue dendrimer complexes 1 (x = 1.9) with a dimer structure. The activation energy for electron transport is estimated to be 0.35 meV. The coordination of the copper ion site (NO4) and the structural arrangement of green complexes 1 (x = 1.9) in the columnar mesophase are determined. Complexes of this type form linear chains in which nitrate counterions serve as bridges between copper centers. It is revealed that green complexes 1 (x = 1.9) dissolved in isotropic inert solvents can be oriented in the magnetic field (B 0 = 8000 G). The degree of orientation of these complexes is rather high (S z = 0.76) and close to that of systems with a complete ordering (S z = 1) in the magnetic field. Copper(0) nanoclusters prepared by reduction of complex 2 (x = 7.3) in two reducing agents (NaBH4, N2H4 · H2O) are examined. A model is proposed for a possible location of Cu(0) nanoclusters in a dendrimer matrix.

  2. Abiotic reduction of nitroaromatic contaminants by iron(II) complexes with organothiol ligands.

    PubMed

    Naka, Daisuke; Kim, Dongwook; Carbonaro, Richard F; Strathmann, Timothy J

    2008-06-01

    Complexation of Fe(II) by dissolved and surface-bound ligands can significantly modify the metal's redox reactivity, and recent work reveals that Fe(II) complexes with selected classes of organic ligands are potent reductants that may contribute to the natural attenuation of subsurface contaminants. In the present study, we investigated the reactivity of Fe(II)-organothiol ligand complexes with nitroaromatic contaminants (NACs; ArNO(2)). Experimental results show that NACs are unreactive in Fe(2+)-only and ligand-only solutions but are reduced to the corresponding aniline compounds (ArNH(2)) in solutions containing both Fe(II) and a number of organothiol ligands. Observed reaction rates are highly dependent on the structure of the Fe(II)-complexing ligand, solution composition, Fe(II) speciation, and NAC structure. For two model ligands, cysteine and thioglycolic acid, observed pseudo-first order rate constants for 4-chloronitrobenzene reduction (k(obs); 1/s) are linearly correlated with the concentration of the respective 1:2 Fe(II)- organothiol complexes (FeL(2)(2-)), and k(obs) measurements are accurately predicted by k(obs) = k(FeL(2-)(2))[FeL(2-)(2)], where k(FeL(2-)(2)) = 1.70 (+/-0.59) 1/M/s and 26.0 (+/-4.8) 1/M/s for cysteine and thioglycolic acid, respectively. The high reactivity of these Fe(II) complexes is attributed to a lowering of the standard one-electron reduction potential of the Fe(III)/Fe(II) redox couple on complexation by organothiol ligands. The relative reactivity of a series of substituted NACs with individual Fe(II) complexes can be described by linear free-energy relationships with the apparent one-electron reduction potentials of the NACs. Tests also show that organothiol ligands can further promote NAC reduction indirectly by re-reducing the Fe(III) that forms when Fe(II) complexes are oxidized by reactions with the NACs.

  3. Multiporphyrin coordination arrays based on complexation of magnesium(II) porphyrins with porphyrinylphosphine oxides.

    PubMed

    Atefi, Farzad; McMurtrie, John C; Arnold, Dennis P

    2007-06-07

    Di- and triporphyrin arrays consisting of 5,15-diphenylporphyrinatomagnesium(II) (MgDPP) coordinated to free-base and Ni(II) porphyrinyl mono- and bis-phosphine oxides, as well as the self-coordinating diphenyl[10,20-diphenylporphyrinatomagnesium(II)-5-yl]phosphine oxide [MgDPP(Ph(2)PO)], were synthesised in excellent yields and characterised by various spectroscopic techniques. Phosphine oxides stabilise Mg(II) coordination to porphyrins and the resulting complexes have convenient solubilities, while the Ni(II) complexes exhibit interesting intramolecular fluorescence quenching behaviour. The binding constant of MgDPP to triphenylphosphine oxide (5.3 +/- 0.1 x 10(5) M(-1)) and the very high self-association constant of [MgDPP(Ph(2)PO)] (5.5 +/- 0.5 x 10(8) M(-1)) demonstrate the strong affinity of phosphine oxides towards Mg(II) porphyrins. These complexes are the first strongly bound synthetic Mg(II) multiporphyrin complexes and could potentially mimic the "special pair" in the photosynthetic reaction centre.

  4. Synthesis of uranyl(II), vanadyl(II) and zirconyl urate complexes, spectral, thermal and biological studies.

    PubMed

    El-Megharbel, Samy M; El-Metwaly, Nashwa M; Refat, Moamen S

    2015-01-01

    Three urate chelations were obtained when uric acid was reacted with UO2(CH3COO)2H2O, VOSO4·XH2O and ZrOCl2·XH2O salts with neutralized with 0.1 M NaOH aqueous media. The 1:2 metal-to-ligand complexes [(UO2)2(C5H2N4O3)2](H2O), [(ZrO)2(H2O)2(C5H2N4O3)2] and [VO((C5H3N4O3)2] were characterized by elemental analyses, molar conductivity, (infrared, Raman and UV-vis) spectra, effective magnetic moment in Bohr magnetons, and thermal analysis (TG/DTG). The urate ligand coordinates as mononegative bidentate donor towards the mononuclear central vanadium atom and coordinated as binegative tetradentate mode towards the binuclear dioxouranium and zirconyl centers. The antibacterial activity of the metal complexes were tested against some kind of bacteria and fungi strains and compared with uric acid. The ligand, ZrO(II) and UO2(II) complex showed a week potential degradation on calf thymus DNA, whereas VO(II) complex slightly degraded the DNA.

  5. Synthesis of uranyl(II), vanadyl(II) and zirconyl urate complexes, spectral, thermal and biological studies

    NASA Astrophysics Data System (ADS)

    El-Megharbel, Samy M.; El-Metwaly, Nashwa M.; Refat, Moamen S.

    2015-10-01

    Three urate chelations were obtained when uric acid was reacted with UO2(CH3COO)2H2O, VOSO4·XH2O and ZrOCl2·XH2O salts with neutralized with 0.1 M NaOH aqueous media. The 1:2 metal-to-ligand complexes [(UO2)2(C5H2N4O3)2](H2O), [(ZrO)2(H2O)2(C5H2N4O3)2] and [VO((C5H3N4O3)2] were characterized by elemental analyses, molar conductivity, (infrared, Raman and UV-vis) spectra, effective magnetic moment in Bohr magnetons, and thermal analysis (TG/DTG). The urate ligand coordinates as mononegative bidentate donor towards the mononuclear central vanadium atom and coordinated as binegative tetradentate mode towards the binuclear dioxouranium and zirconyl centers. The antibacterial activity of the metal complexes were tested against some kind of bacteria and fungi strains and compared with uric acid. The ligand, ZrO(II) and UO2(II) complex showed a week potential degradation on calf thymus DNA, whereas VO(II) complex slightly degraded the DNA.

  6. Zinc(II) and Cadmium(II) complexes with N4-coordinate pyrazole based ligand: Syntheses, characterization and structure

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    A series of six new mononuclear zinc(II) complexes of the type [Zn(X)(dbdmp)]Y (1-6) (X = N3-/NCO-/NCS-, Y = ClO4-/PF6-, and dbdmp = N,N-diethyl-N‧,N‧-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine), two binuclear cadmium(II) complexes [{Cd(dbdmp)}2(μ-N3)2](Y)2 (7-8) and three mononuclear cadmium(II) complexes [Cd(NCO)(dbdmp)]Y (Y = ClO4-/PF6-) (9-10) and [Cd(NCS)2(dbdmp)] (11) have been synthesized and characterized by physico-chemical methods. Crystal structures of the complexes [Zn(N3)(dbdmp)]ClO4 (1), [{Cd(dbdmp)}2(μ-N3)2](ClO4)2 (7), [Cd(NCO)(dbdmp)]ClO4 (9) and [Cd(NCS)2(dbdmp)] (11) have been solved by single crystal X-ray diffraction studies and showed that [Zn(N3)(dbdmp)]ClO4 (1) and [Cd(NCO)(dbdmp)]ClO4 (9) have distorted trigonal bipyramidal geometry, [Cd(NCS)2(dbdmp)] (11) and [(dbdmp)Cd(μ-N3)]2(ClO4)2 (7) have distorted octahedral geometry.

  7. Co(II) and Cd(II) Complexes Derived from Heterocyclic Schiff-Bases: Synthesis, Structural Characterisation, and Biological Activity

    PubMed Central

    Ahmed, Riyadh M.; Yousif, Enaam I.; Al-Jeboori, Mohamad J.

    2013-01-01

    New monomeric cobalt and cadmium complexes with Schiff-bases, namely, N′-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]furan-2-carbohydrazide (L1) and N′-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]thiophene-2-carbohydrazide (L2) are reported. Schiff-base ligands L1 and L2 were derived from condensation of 3-hydroxy-4-methoxybenzaldehyde (iso-vanillin) with furan-2-carboxylic acid hydrazide and thiophene-2-carboxylic acid hydrazide, respectively. Complexes of the general formula [M(L)2]Cl2 (where M = Co(II) or Cd(II), L = L1 or L2) have been obtained from the reaction of the corresponding metal chloride with the ligands. The ligands and their metal complexes were characterised by spectroscopic methods (FTIR, UV-Vis, 1H, and 13C NMR spectra), elemental analysis, metal content, magnetic measurement, and conductance. These studies revealed the formation of four-coordinate complexes in which the geometry about metal ion is tetrahedral. Biological activity of the ligands and their metal complexes against gram positive bacterial strain Bacillus (G+) and gram negative bacteria Pseudomonas (G−) revealed that the metal complexes become less resistive to the microbial activities as compared to the free ligands. PMID:24027449

  8. Co(II) and Cd(II) complexes derived from heterocyclic Schiff-Bases: synthesis, structural characterisation, and biological activity.

    PubMed

    Ahmed, Riyadh M; Yousif, Enaam I; Al-Jeboori, Mohamad J

    2013-01-01

    New monomeric cobalt and cadmium complexes with Schiff-bases, namely, N'-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]furan-2-carbohydrazide (L¹) and N'-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]thiophene-2-carbohydrazide (L²) are reported. Schiff-base ligands L¹ and L² were derived from condensation of 3-hydroxy-4-methoxybenzaldehyde (iso-vanillin) with furan-2-carboxylic acid hydrazide and thiophene-2-carboxylic acid hydrazide, respectively. Complexes of the general formula [M(L)₂]Cl₂ (where M = Co(II) or Cd(II), L = L¹ or L²) have been obtained from the reaction of the corresponding metal chloride with the ligands. The ligands and their metal complexes were characterised by spectroscopic methods (FTIR, UV-Vis, ¹H, and ¹³C NMR spectra), elemental analysis, metal content, magnetic measurement, and conductance. These studies revealed the formation of four-coordinate complexes in which the geometry about metal ion is tetrahedral. Biological activity of the ligands and their metal complexes against gram positive bacterial strain Bacillus (G+) and gram negative bacteria Pseudomonas (G-) revealed that the metal complexes become less resistive to the microbial activities as compared to the free ligands.

  9. Synthesis, physicochemical properties, and in vitro antibacterial screening of palladium(II) complexes derived from thiosemicarbazone.

    PubMed

    Azam, Mohammad; Warad, Ismail; Al-Resayes, Saud I; Siddiqui, M Rafiq; Oves, M

    2013-06-01

    A new series of PdII complexes derived from thiosemicarbazone has been synthesized. The synthesized PdII complexes have been characterized on the basis of elemental analyses, FT-IR, ¹H- and ¹³C-NMR, UV/VIS, and thermal studies. A square-planar geometry has been assigned around PdII ions on the basis of results obtained from UV/VIS studies. The thiosemicarbazone ligand and its PdII complexes have been screened against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria in vitro as growth-inhibiting agents, and the results revealed significant antibacterial activities.

  10. Extended X-ray absorption studies of copper (II) dibenzoyal methane diquinoline complexes

    NASA Astrophysics Data System (ADS)

    Mishra, A.; Sharma, P.; Malviya, P. K.

    2013-06-01

    X-ray K-absorption spectroscopic studies have been carried out on copper (II) mixed-ligand complexes. Copper is a transition metal, which in the zero oxidation state has an electron configuration of [Ar] 4s24p63d9. Copper is found in three different oxidation states: Cu(I), Cu(II), and Cu(III). In the copper (II) oxidation state, the metal has 9 d electrons. Jahn-Teller distortion causes a splitting of eg and t2g orbitals. Most Cu(II) complexes are square planar for this reason. In a series of those compounds, we have prepared copper (II) complexes containing two nitrato ligands and a 2,2'-dipyridylamine(dpa) derivative ligand. The 2,2' - dipyridylamine and its derivatives have been widely used for metal complexes because of their good chelating property, structural flexibility. we have estimated the average metalligand bond distances from the fine structure data. We have determined the bond lengths for the copper (II) complexes with the help of Levy's, LSS, Fourier transform, Lytle's Methods.

  11. Hybrid Core-Shell (HyCoS) Nanoparticles produced by Complex Coacervation for Multimodal Applications

    PubMed Central

    Vecchione, D.; Grimaldi, A. M.; Forte, E.; Bevilacqua, Paolo; Netti, P. A.; Torino, E.

    2017-01-01

    Multimodal imaging probes can provide diagnostic information combining different imaging modalities. Nanoparticles (NPs) can contain two or more imaging tracers that allow several diagnostic techniques to be used simultaneously. In this work, a complex coacervation process to produce core-shell completely biocompatible polymeric nanoparticles (HyCoS) for multimodal imaging applications is described. Innovations on the traditional coacervation process are found in the control of the reaction temperature, allowing a speeding up of the reaction itself, and the production of a double-crosslinked system to improve the stability of the nanostructures in the presence of a clinically relevant contrast agent for MRI (Gd-DTPA). Through the control of the crosslinking behavior, an increase up to 6 times of the relaxometric properties of the Gd-DTPA is achieved. Furthermore, HyCoS can be loaded with a high amount of dye such as ATTO 633 or conjugated with a model dye such as FITC for in vivo optical imaging. The results show stable core-shell polymeric nanoparticles that can be used both for MRI and for optical applications allowing detection free from harmful radiation. Additionally, preliminary results about the possibility to trigger the release of a drug through a pH effect are reported. PMID:28327584

  12. Hybrid Core-Shell (HyCoS) Nanoparticles produced by Complex Coacervation for Multimodal Applications

    NASA Astrophysics Data System (ADS)

    Vecchione, D.; Grimaldi, A. M.; Forte, E.; Bevilacqua, Paolo; Netti, P. A.; Torino, E.

    2017-03-01

    Multimodal imaging probes can provide diagnostic information combining different imaging modalities. Nanoparticles (NPs) can contain two or more imaging tracers that allow several diagnostic techniques to be used simultaneously. In this work, a complex coacervation process to produce core-shell completely biocompatible polymeric nanoparticles (HyCoS) for multimodal imaging applications is described. Innovations on the traditional coacervation process are found in the control of the reaction temperature, allowing a speeding up of the reaction itself, and the production of a double-crosslinked system to improve the stability of the nanostructures in the presence of a clinically relevant contrast agent for MRI (Gd-DTPA). Through the control of the crosslinking behavior, an increase up to 6 times of the relaxometric properties of the Gd-DTPA is achieved. Furthermore, HyCoS can be loaded with a high amount of dye such as ATTO 633 or conjugated with a model dye such as FITC for in vivo optical imaging. The results show stable core-shell polymeric nanoparticles that can be used both for MRI and for optical applications allowing detection free from harmful radiation. Additionally, preliminary results about the possibility to trigger the release of a drug through a pH effect are reported.

  13. FORTRAN subroutines for out-of-core solutions of large complex linear systems

    NASA Technical Reports Server (NTRS)

    Yip, E. L.

    1979-01-01

    The design and usage of two main subprograms using direct methods to solve large linear complex systems, of the form Ax = b, whose coeffficient matrices are too large to be stored in core are described. The first main subprogram is for systems whose coefficient matrices are of a particular sparse structure, namely, the matrix A can be written in the form B + D, where B is a block-banded system, and D has only a few columns of nonzeros. Key elements of the algorithms used in the subprograms include: the data structure, the strategy for preserving numerical stability, the adaptability of the algorithms for dense systems as well as for block-profile systems.

  14. An assessment of the Arctic Ocean in a suite of interannual CORE-II simulations: Hydrography and fluxes

    NASA Astrophysics Data System (ADS)

    Ilicak, Mehmet; Drange, Helge

    2016-04-01

    We compare the simulated Arctic Ocean in fifteen global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE-II). Most of these models are the ocean and sea-ice components of the coupled climate models used in the Coupled Model Intercomparison Project Phase 5 (CMIP5) experiments. We mainly focus on the hydrography of the Arctic interior, the state of Atlantic Water layer and heat and volume transports at the gateways of the Davis Strait, the Bering Strait, the Fram Strait and the Barents Sea Opening. We found that there is a large spread in temperature in the Arctic Ocean between the models, and generally large differences compared to the observed temperature at intermediate depths. Warm bias models have a strong temperature anomaly of inflow of the Atlantic Water entering the Arctic Ocean through the Fram Strait. Another process that is not represented accurately in the CORE-II models is the formation of cold and dense water, originating on the eastern shelves. In the cold bias models, excessive cold water forms in the Barents Sea and spreads into the Arctic Ocean through the St. Anna Through. There is a large spread in the simulated mean heat and volume transports through the Fram Strait and the Barents Sea Opening. The models agree more on the decadal variability, to a large degree dictated by the common atmospheric forcing. We conclude that the CORE-II model study helps us to understand the crucial biases in the Arctic Ocean. The current coarse resolution state-of-the-art ocean models need to be improved in accurate representation of the Atlantic Water inflow into the Arctic and density currents coming from the shelves.

  15. Macrocyclic nickel(II) complexes: Synthesis, characterization, superoxide scavenging activity and DNA-binding

    NASA Astrophysics Data System (ADS)

    Ramadan, Abd El-Motaleb M.

    2012-05-01

    A new series of nickel(II) complexes with the tetraaza macrocyclic ligand have been synthesized as possible functional models for nickel-superoxide dismutase enzyme. The reaction of 5-amino-3-methyl-1-phenylpyrazole-4-carbaldehyde (AMPC) with itself in the presence of nickel(II) ion yields, the new macrocyclic cationic complex, [NiL(NO3)2], containing a ligand composed of the self-condensed AMPC (4 mol) bound to a single nickel(II) ion. A series of metathetical reactions have led to the isolation of a number of newly complexes of the types [NiL]X2; X = ClO4 and BF4, [NiLX2], X = Cl and Br (Scheme 1). Structures and characterizations of these complexes were achieved by several physicochemical methods namely, elemental analysis, magnetic moment, conductivity, and spectral (IR and UV-Vis) measurements. The electrochemical properties and thermal behaviors of these chelates were investigated by using cyclic voltammetry and thermogravimetric analysis (TGA and DTG) techniques. A distorted octahedral stereochemistry has been proposed for the six-coordinate nitrato, and halogeno complexes. For the four-coordinate, perchlorate and fluoroborate, complex species a square-planar geometry is proposed. The measured superoxide dismutase mimetic activities of the complexes indicated that they are potent NiSOD mimics and their activities are compared with those obtained previously for nickel(II) complexes. The probable mechanistic implications of the catalytic dismutation of O2rad - by the synthesized nickel(II) complexes are discussed. The DNA-binding properties of representative complexes [NiLCl2] and [NiL](PF4)2 have been investigated by the electronic absorption and fluorescence measurements. The results obtained suggest that these complexes bind to DNA via an intercalation binding mode and the binding affinity for DNA follows the order: [NiLCl2] □ [NiL](PF4)2.

  16. DNA cleavage, antimicrobial, spectroscopic and fluorescence studies of Co(II), Ni(II) and Cu(II) complexes with SNO donor coumarin Schiff bases

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Naik, Vinod H.; Kulkarni, Ajaykumar D.; Badami, Prema S.

    2010-01-01

    A series of Co(II), Ni(II) and Cu(II) complexes of the type ML 2 have been synthesized with Schiff bases derived from methylthiosemicarbazone and 5-formyl-6-hydroxy coumarin/8-formyl-7-Hydroxy-4-methylcoumarin. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMF indicate that, the complexes are non-electrolytes in nature. In view of analytical, spectral (IR, UV-vis, ESR, FAB-mass and fluorescence), magnetic and thermal studies, it has been concluded that, all the metal complexes possess octahedral geometry in which ligand is coordinated to metal ion through azomethine nitrogen, thione sulphur and phenolic oxygen atom via deprotonation. The redox behavior of the metal complexes was investigated by using cyclic voltammetry. The Schiff bases and their complexes have been screened for their antibacterial ( Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi) and antifungal activities ( Aspergillus niger, Aspergillus flavus and Cladosporium) by Minimum Inhibitory Concentration method. The DNA cleavage is studied by agarose gel electrophoresis method.

  17. Synthesis, structural and biochemical activity studies of a new hexadentate Schiff base ligand and its Cu(II), Ni(II), and Co(II) complexes

    NASA Astrophysics Data System (ADS)

    Ekmekcioglu, Pinar; Karabocek, Nevin; Karabocek, Serdar; Emirik, Mustafa

    2015-11-01

    A new Schiff base ligand (H2L) and its metal complexes have been prepared and characterized by elemental analysis, magnetic moment and spectral studies. The comparative in-vitro antimicrobial activities against various pathogens with reference to known antibiotics activity under the standard control of different concentrations revealed that the metal complexes (6-8) showed enhanced antimicrobial activities in general as compared to free ligand. As an exception, the free ligand showed better activity against Trichoderma. The antifungal activity experiments were performed in triplicate. The order of biochemical activity for metal complexes were observed as in the following. CuL > CoL > NiL, which is exactly same as the order of stability constants of these complexes. Additionally, we performed DFT and TD-DFT calculation for free ligand and Cu(II) complex to support the experimental data. The geometries of the Cu(II) complex have been optimized using the B3LYP level of theory. The theoretical calculations confirm that the copper (II) center exhibits a distorted square pyramidal geometry which is favored by experimental results.

  18. Copper (II) complexes possessing alkyl-substituted polypyridyl ligands: Structural characterization and in vitro antitumor activity.

    PubMed

    Angel, Noah R; Khatib, Raneen M; Jenkins, Julia; Smith, Michelle; Rubalcava, Justin M; Le, Brian Khoa; Lussier, Daniel; Chen, Zhuo Georgia; Tham, Fook S; Wilson, Emma H; Eichler, Jack F

    2017-01-01

    In an effort to find alternatives to the antitumor drug cisplatin, a series of copper (II) complexes possessing alkyl-substituted polypyridyl ligands have been synthesized. Eight new complexes are reported herein: μ-dichloro-bis{2,9-di-sec-butyl-1,10-phenanthrolinechlorocopper(II)} {[((di-sec-butyl)phen)ClCu(μ-Cl)2CuCl((di-sec-butyl)phen)]}(1), 2-sec-butyl-1,10-phenanthrolinedichlorocopper(II) {([mono-sec-butyl)phen) CuCl2} (2), 2,9-di-n-butyl-1,10-phenanthrolinedichlorocopper(II) {[(di-n-butyl)phen) CuCl2}(3), 2-n-butyl-1,10-phenanthrolinedichlorocopper(II) {[(mono-n-butyl)phen) CuCl2} (4), 2,9-di-methyl-1,10-phenanthrolineaquadichlorocopper(II) {[(di-methyl)phen) Cu(H2O)Cl2}(5), μ-dichloro-bis{6-sec-butyl-2,2'-bipyridinedichlorocopper(II)} {((mono-sec-butyl)bipy) ClCu(μ-Cl)2CuCl((mono-sec-butyl)bipy)} (6), 6,6'-di-methyl-2,2'-bipyridinedichlorocopper(II) {(6,6'-di-methyl)bipy) CuCl2} (7), and 4,4'-dimethyl-2,2'-bipyridinedichlorocopper(II) {(4,4'-di-methyl)bipy) CuCl2} (8). These complexes have been characterized via elemental analysis, UV-vis spectroscopy, and mass spectrometry. Single crystal X-ray diffraction experiments revealed the complexes synthesized with the (di-sec-butyl)phen ligand (1) and (mono-sec-butyl)bipy ligand (6) crystallized as dimers in which two copper(II) centers are bridged by two chloride ligands. Conversely, complexes 2, 7, and 8 were isolated as monomeric species possessing distorted tetrahedral geometries, and the [((di-methyl)phen)Cu(H2O)Cl2] (5) complex was isolated as a distorted square pyramidal monomer possessing a coordinating aqua ligand. Compounds 1-8 were evaluated for their in vitro antitumor efficacy. Compounds 1, 5, and 7 in particular were found to exhibit remarkable activity against human derived lung cancer cells, yet this class of copper(II) compounds had minimal cytotoxic effect on non-cancerous cells. In vitro control experiments indicate the activity of the copper(II) complexes most likely does not arise from the

  19. Cellular localization of iron(II) polypyridyl complexes determines their anticancer action mechanisms.

    PubMed

    Chen, Jingjing; Luo, Zuandi; Zhao, Zhennan; Xie, Lina; Zheng, Wenjie; Chen, Tianfeng

    2015-12-01

    Elucidation of relationship among cellular uptake, localization and biological activities of metal complexes could make great breakthrough in the understanding of their action mechanisms and provide useful information for rational design of metal-based anticancer drugs. Iron(II) complexes have emerged as potential anticancer drug candidates with application potential in cancer imaging and therapy. Herein, a series of iron(II) polypyridyl complexes with different lipophilicity were rationally designed, synthesized and identified as potent anticancer agents. The relationship between the cellular localization and molecular action mechanisms of the complexes was also elucidated. The results showed that, the increase in planarity of the Fe(II) polypyridyl complexes enhanced their lipophilicity and cellular uptake, leading to improved anticancer efficacy. The hydrophilic Fe(II) complex entered cancer cells through transferring receptor (TfR)-mediated endocytosis, and translocated to cell nucleus, where they induced S phase cell cycle arrest through triggering DNA damage-mediated p53 pathway. Interestingly, the hydrophobic Fe(II) complexes displayed higher anticancer efficacy than the hydrophilic ones, but shared the same uptake pathway (TfR-mediated endocytosis) in cancer cells. They accumulated and localized in cell cytoplasm, and induced G0/G1 cells cycle arrest through regulation of AKT pathway and activation of downstream effector proteins. These results support that the cellular localization of Fe(II) complexes regulated by their lipophilicity could affect the anticancer efficacy and action mechanisms. Taken together, this study may enhance our understanding on the rational design of the next-generation anticancer metal complexes.

  20. Bathophenanthroline-Ru(II) complexes as nonradioactive labels for dideoxy DNA sequencing.

    PubMed

    Bannwarth, W

    1989-09-01

    Bathophenanthroline-Ru(II) complexes represent interesting nonradioactive label molecules which can be measured in a time-resolved mode with high sensitivity. Here we demonstrate that Ru complex-labeled primers can be applied in dideoxy sequencing protocols giving the same sequencing patterns as unlabeled primers.

  1. Catalytic dioxygen activation by Co(II) complexes employing a coordinatively versatile ligand scaffold.

    PubMed

    Sharma, Savita K; May, Philip S; Jones, Matthew B; Lense, Sheri; Hardcastle, Kenneth I; MacBeth, Cora E

    2011-02-14

    The ligand bis(2-isobutyrylamidophenyl)amine has been prepared and used to stabilize both mononuclear and dinuclear cobalt(II) complexes. The nuclearity of the cobalt product is regulated by the deprotonation state of the ligand. Both complexes catalytically oxidize triphenylphosphine to triphenylphosphine oxide in the presence of O(2).

  2. A synthetic model for the oxygen-evolving complex in Sr(2+)-containing photosystem II.

    PubMed

    Chen, Changhui; Zhang, Chunxi; Dong, Hongxing; Zhao, Jingquan

    2014-08-25

    A novel heterometallic MnSr complex containing the Mn3SrO4 cuboidal moiety and all types of μ-O(2-) moieties observed in the oxygen-evolving complex (OEC) in Sr(2+)-containing photosystem II (PSII) has been synthesized and characterized, which provides a new synthetic model of the OEC.

  3. Dinuclear and heptanuclear complexes of copper(II) with 7-azaindole ligand: synthesis, characterization, magnetic properties, and biological activity.

    PubMed

    Przyojski, Jacob A; Myers, Nicole N; Arman, Hadi D; Prosvirin, Andrey; Dunbar, Kim R; Natarajan, Mohan; Krishnan, Manickam; Mohan, Sumathy; Walmsley, Judith A

    2013-10-01

    Three new complexes of Cu(II) with 7-azaindole have been synthesized and characterized, a dicopper compound, [Cu(C7H5N2)2(H2O)]2·2CH3CN, 1, and two heptacopper compounds [Cu7(C7H5N2)6(μ3-OH)6(μ2-H2O)2(μ2-CH3OH)4](CH3COO)2·2C7H8·6CH3OH, 2, and [Cu7(C7H5N2)5(CH3COO)(μ3-OH)6(μ2-H2O)4(μ2-CH3OH)2](CH3COO)2, 4. The structure of 2 is monoclinic and it crystallizes in the P21/c space group: a=13.475(4)Å; b=12.945(4)Å; c=23.392(7)Å; β=91.232(6)°. It contains a unique Cu7O12 core in which a central Cu(II) is situated at an inversion center and is bonded to 6 other Cu(II) ions via bridging oxygen atoms from OH(-), H2O, and CH3OH groups. Anionic 7-azaindole ligands bridge between adjacent outer Cu(II) ions and all Cu(II) ions have distorted octahedral coordination geometries. Variable temperature magnetic susceptibility measurements revealed the presence of antiferromagnetic exchange interactions between Cu(II) ions which leads to an S=5/2 ground state at 1.8K. Cytotoxicity and cell proliferation activities of the Cu compounds using human tongue squamous cell carcinoma and normal cells revealed that the compounds stimulated proliferation in both types of cells.

  4. The Eastern Pelagonian metamorphic core complex: insight from the 40Ar/39Ar dating of white micas

    NASA Astrophysics Data System (ADS)

    Schenker, F. L.; Forster, M.; Burg, J.-P.

    2012-04-01

    The Pelagonian Zone in continental Greece is the westernmost unit of the Internal Hellenides that constitutes a pre-alpine crystalline block in-between two oceanic domains, the Pindos in the west and the Vardar zone in the east. We present petrographic, structural and geochronological evidence for a metamorphic core complex in eastern Pelagonian. The denuded metamorphic dome extends about 20 x 15 km with the long axis striking NNW-SSE. A shallow-dipping foliation defines the structural dome. The mineralogy of the lithologies (gneiss, impure marbles and amphibolites) show metamorphic conditions that decrease from upper-amphibolite in the core to greenschist metamorphic conditions in the flanks of the dome, reflecting structural depth and thus erosion of the dome. Aligned micas and amphiboles and elongated quartz and feldspar define a prominent lineation trending SW-NE. Asymmetric structures in the XZ finite strain plane of rocks show two regional senses of shear: (i) everywhere, top-to-the-SW sense of shear (direction: 252°±30; plunge: 8°±25) associated with strain gradients from protomylonite to ultramylonite and recumbent, isoclinal and occasional sheath folds; (ii) top-to-the-E sense of shear (direction: 88°±24; plunge: 11°±12) in narrow (0.1 to 100 m) low-angle shear zones on the eastern flanks of subdomes. The 40Ar/39Ar step-heating dating technique has been applied to micas from orthogneisses from the core to the flanks of the dome to constrain its thermal and structural evolution. The micas have been separated with acoustical shockwave produced in the SELFRAG apparatus, with the advantage to liberate morphologically intact grains. The liberated grains were sieved at different grain-sizes (between 100 and 300 μm) depending on the micro-textures observed in thin-sections. Results show "plateau"-ages at ca. 100-120 Ma and at ca. 80 Ma. Interestingly, the 100-160 μm fraction of white micas in a mylonitic orthogneiss yielded slightly younger ages than

  5. Pliocene Core Complex Exhumation on Land and Rapid Subsidence in Gorontalo Bay, Sulawesi (Indonesia)

    NASA Astrophysics Data System (ADS)

    Pezzati, G.; Hall, R.; Burgess, P.; Perez-Gussinye, M.

    2014-12-01

    Gorontalo Bay is a semi-enclosed sea between the North and East Arms of Sulawesi. It is surrounded by land on three sides, separating a northern volcanic province from metamorphic rocks to the south and west, and ophiolites to the southeast. Recently acquired multibeam bathymetry and 2D seismic data suggest a link between core complex exhumation on land and offshore subsidence driven by major young extension. In western Gorontalo Bay are two sub-basins with different histories: Tomini Basin in the north and Poso Basin in the south. In Tomini Basin six major seismic sequences (Units A to F) have a total thickness over 5 sec TWT. Ages are based on interpreted correlations with events on land. Basement Unit A subsided from the Early Miocene, with deposition of Units B and C, largely in a deep marine environment. There was regional uplift in the Middle Miocene. Carbonate platforms were thereafter deposited in shallow marine environments (Units D-E). The platforms show a wedge geometry that suggests tilting of the basin during their deposition. Subsidence accelerated during the deposition of Unit E in the Early Pliocene, causing backstepping of the shelf edge, formation of pinnacle reefs and then drowning of the carbonate platforms, leading to present depths of 2 km in the basin centre (Unit F). Poso Basin is younger than Tomini Basin and forms the southern part of western Gorontalo Bay. The deeper part of its sedimentary sequence is probably the time equivalent of Unit D in Tomini Basin. It contains a complex deformed sequence of sediments, up to 3 sec TWT, that are the probable equivalent of Units E and F to the north. On land to the south of Poso Basin is a large metamorphic core complex. Seismic data suggest that the northern flank of the complex can be traced into a potential low angle normal fault under the basin that caused subsidence offshore. Low T thermochronology and alluvial sediment records on land suggest major uplift and subsidence occurred in the

  6. Tuning tetranuclear manganese-oxo core electronic properties: adamantane-shaped complexes synthesized by ligand exchange.

    PubMed